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Neuroendocrine tumor (NET) is a rare malignant tumor, notably small cell lung cancer (SCLC), a type of lung neuroendocrine tumor, which has a survival rate of less than 7%. Although various biomarkers including CHGA (Chromogranin A), INSM1 (Insulinoma-associated protein 1), and SYP (Synaptophysin) are extensively used for the diagnostic testing of NET, their diverse specificities and sensitivities are acknowledged as limitations. Here, we demonstrate that RepID (Replication initiation determinant protein), a component of CRL4 (Cullin-RING ubiquitin E3 ligase 4), holds promise as a biomarker for identifying NET and SCLC. Analysis of the Cancer Cell Line Encyclopedia (CCLE) via the CellMinerCDB portal reveals a high correlation between RepID transcript levels and mRNA expression of NE signature genes. Additionally, RepID protein is highly expressed in SCLC patient tissues and a subset of SCLC cell lines. Viability analysis following treatment with pevonedistat and SZL-P1-41 in SCLC cell lines and human SCLC-organoid models indicates that RepID expression determines the sensitivity to CRL-targeting anti-cancer drugs. These findings suggest that RepID represents a novel biomarker for NET and SCLC, and insights from RepID research in these cancers could lead to innovative therapeutic strategies., Competing Interests: Declarations Competing interests The authors declare no competing interests. Consent for publication Not applicable., (© 2024. The Author(s).)

Background/aim: Large extracellular vesicles (lEV) offer a unique window into the metabolism of their cells of orign and dysregulation of lipid metabolism has been described in patients with small cell lung cancer (SCLC). Therefore, metabolomic profiling of patients' lEVs may offer insight into cancer metabolism as well as new potential biomarkers for monitoring disease progression., Materials and Methods: lEVs were isolated by differential centrifugation from the peripheral blood of SCLC patients and healthy controls. Targeted mass spectrometry was used to analyze the lipid composition of lEVs. After identifying relevant metabolites, biomarker and pathway analysis were conducted., Results: SCLC patients exhibited a distinct metabolic profile compared to healthy controls. The metabolites TG(16:0:_38:3), TG(18:3_35:2), TG(16:0_40:7), Cer(d18:1/26:0), and CE(16:0) are not only able to discriminate between patients and control samples, but are also served as prognostic markers for survival. Patients with high concentrations of these metabolites showed significantly shorter survival times. Pathway analysis revealed alterations in 'sphingolipid metabolism', 'sphingolipid signaling pathway' and 'necroptosis'., Conclusion: Metabolic profiling of lEVs in SCLC patients is feasible and reveals a distinct metabolic profile. High concentrations of identified lipids are associated with poor prognosis., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

As reported, long non-coding RNAs (lncRNAs) have been confirmed to be of great importance in regulating the progression of diseases, especially of cancers. LncRNA MACC1 antisense RNA 1 (MACC1-AS1) has been studied in some cancers, whereas its biological role and underlying mechanism is still unclear in small cell lung cancer (SCLC). In the current research, we found high level of MACC1-AS1 in SCLC cells. Subsequently, it was discovered that MACC1-AS1 knockdown considerably restrained the proliferative and migratory ability of SCLC cells by inducing the apoptosis. Importantly, the knockdown of MACC1-AS1 inhibited protein levels of genes of NOTCH pathway, and NOTCH pathway activator (Jagged1) countervailed the inhibition of MACC1-AS1 depletion on SCLC cell growth. Further, the deficiency of NOTCH1 hampered SCLC cell growth. More importantly, miR-579-3p was identified as a downstream gene of MACC1-AS1 and thereby targeted to NOTCH1. In addition, miR-579-3p repression recovered the suppressive role of MACC1-AS1 knockdown in NOTCH1 expression. Rescue assays indicated that repressed SCLC cell growth caused by MACC1-AS1 knockdown could be reserved by miR-579-3p repression or NOTCH1 overexpression. In brief, lncRNA MACC1-AS1 boosted SCLC cell growth via sequestering miR-579-3p and mediating NOTCH1-pathway., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Small cell lung cancer (SCLC) stands as one of the most lethal malignancies, characterized by a grim diagnosis and prognosis. The emergence of multi-drug resistance poses a significant hurdle to effective therapy. Although previous studies have implicated the long noncoding RNA LYPLAL1-DT in the tumorigenesis of SCLC, the precise role of the highly expressed LYPLAL1-DT in SCLC chemoresistance and the underlying mechanism remain inadequately understood., Methods: cDDP-, VP-16- and PTX-resistant SCLC cells lines were established. The viabilities of SCLC cells were assessed by CCK-8 assay in vitro and xenograft tumor formation assay in vivo. Apoptosis was evaluated by FACS, Western blot and JC-1 fluorescence staining, while autophagy was explored via autophagic flux detection under confocal microscopy and autophagic vacuole investigation under transmission electron microscopy (TEM). The functional role and mechanism of LYPLAL1-DT were further investigated by gain- and loss-of-function assays in vitro. Furthermore, the therapeutic efficacy of the combination of venetoclax and HCQ with cDDP, VP-16 or PTX was evaluated by cell line, cell-derived xenograft (CDX) and patient-derived xenograft (PDX) mice model., Results: Our findings revealed that LYPLAL1-DT is upregulated in chemoresistant SCLC cell lines. Gain- and loss-of-function assays demonstrated that LYPLAL1-DT impairs sensitivity to cDDP, VP-16, or PTX both in vitro and in vivo. Overexpression of LYPLAL1-DT significantly enhanced autophagy and inhibited apoptosis in SCLC cells. Further analyses, including RIP and RNA pull-down assays, revealed that LYPLAL1-DT promotes the expression of BCL2 by sponging miR-204-5p and is implicated in the assembly of the autophagy-specific complex (BECN1/PtdIns3K complex). Combining venetoclax and HCQ with cDDP, VP-16, or PTX effectively mitigated chemoresistance in SCLC cells and suppressed tumor growth in CDX and PDX models without inducing obvious toxic effects., Conclusions: Our findings demonstrate that upregulation of LYPLAL1-DT sequesters apoptosis through the LYPLAL1-DT/miR-204-5p/BCL2 axis and promotes autophagy by facilitating the assembly of the BECN1/PtdIns3K complex, thereby mediating multi-drug resistance of SCLC. The triple combination of venetoclax, HCQ, in conjunction with cDDP, VP-16 or PTX overcomes refractory SCLC, shedding light on a potential therapeutic target for combating SCLC chemoresistance., (© 2024. The Author(s).)

Understanding transcriptional responses to chemical perturbations is central to drug discovery, but exhaustive experimental screening of disease-compound combinations is unfeasible. To overcome this limitation, here we introduce PRnet, a perturbation-conditioned deep generative model that predicts transcriptional responses to novel chemical perturbations that have never experimentally perturbed at bulk and single-cell levels. Evaluations indicate that PRnet outperforms alternative methods in predicting responses across novel compounds, pathways, and cell lines. PRnet enables gene-level response interpretation and in-silico drug screening for diseases based on gene signatures. PRnet further identifies and experimentally validates novel compound candidates against small cell lung cancer and colorectal cancer. Lastly, PRnet generates a large-scale integration atlas of perturbation profiles, covering 88 cell lines, 52 tissues, and various compound libraries. PRnet provides a robust and scalable candidate recommendation workflow and successfully recommends drug candidates for 233 diseases. Overall, PRnet is an effective and valuable tool for gene-based therapeutics screening., (© 2024. The Author(s).)

This study presents an observational, cross-sectional analysis of 64 patients diagnosed with small cell lung cancer (SCLC) at a reference laboratory for thoracic pathology between 2022 and 2024. The primary objective was to evaluate the expression of Delta-like ligand 3 (DLL3) and other neuroendocrine markers such as Chromogranin, and Synaptophysin, utilizing both traditional immunohistochemistry and digital pathology tools. Patients were primarily older adults, with a median age of over 71, and most biopsies were obtained from lung parenchyma. Immunohistochemistry (IHC) was performed using specific monoclonal antibodies, with DLL3 showing variable expression across the samples. Notably, DLL3 was expressed in 72.3% of the cases, with varied intensities and a semi-quantitative H-score applied for more nuanced analysis. ASCL1 was expressed in 97% of cases, with the majority considered low-expressors. Only 11% had high expression. TTF-1, traditionally not a conventional marker for the diagnosis of SCLC, was positive in half of the cases, suggesting its potential as a biomarker. The study underscores the significant variability in the expression of neuroendocrine markers in SCLC, with implications for both diagnosis and potential therapeutic targeting. DLL3, particularly, shows promise as a therapeutic target due to its high expression rate in the cohort. The use of digital pathology software QuPath enhanced the accuracy and depth of analysis, allowing for detailed morphometric analysis and potentially informing more personalized treatment approaches. The findings emphasize the need for further research into the role of these markers in the management and treatment of SCLC, considering the poor prognosis and high mortality rate observed in the cohort.

Malignant tumors of the lung are the leading cancers worldwide. Prognostic biomarkers continue to be investigated for the detection and stratification of lung cancer for clinical use. In breast cancer cells and in lymphomas, the overexpression of galectin-7 led to increased metastasis. In lung cancer, squamous cell carcinoma, galectin-7 was also identified as a factor promoting metastasis. In this study, we investigated the expression of galectin-7 in relation to clinicopathological features and overall survival in patients with different types of lung cancer. By immunohistochemistry, expression of galectin-7 was analyzed in 308 cases of lung cancer; 108 cases of adenocarcinoma, 193 cases of squamous cell lung carcinoma and 7 cases of small cell lung cancer (SCLC) and correlated with clinicopathological characteristics as well as patients' overall survival. Immunohistochemical detection of galectin-7 expression was most evident in squamous cell lung carcinoma (36.27%), followed by adenocarcinoma (5.55%). Negative expression of galectin-7 was found in all patients with SCLC. No significant correlation was found in patients with squamous cell lung carcinoma. Within the adenocarcinoma and squamous cell lung carcinoma subgroups, there were statistically significant correlations between the expression of galectin-7 and some clinicopathologic features of the patients. In our study, we were able to show that galectin-7 could serve as a new prognostic biomarker and is also a potential new drug target in non-small cell lung cancer., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

This study evaluates the efficacy of [ 131 I]I-ERIC1 in targeting and inhibiting the growth of SCLC tumors in mice, focusing on tumor accumulation and regression and potential side effects. NCAM-positive NCI-H69 SCLC cells were implanted in CB 17 SCID mice, and [ 131 I]I-ERIC1 biokinetics were measured in organs and tissues at four post-injection time points (24, 72, 96, and 120 h). The experimental series compared tumor growth, survival, and changes in blood counts among three treatment groups (1, 2, or 3 MBq) and a control group, with treatments initiated either two or five days post implantation. [ 131 I]I-ERIC1 was synthesized with >95% radiochemical purity and a specific activity of 15 TBq/mmol. Tumor activity peaked at 31.5 ± 6.6% ID/g after four days, demonstrating significant antitumor efficacy, which resulted in sustained remission and extended survival. Hematological toxicity was observed, with the optimal dose identified as 2 MBq per animal administered two days post implantation. [ 131 I]I-ERIC1 shows promise as a theranostic agent for personalized cancer treatment by effectively targeting SCLC tumors with manageable side effects. However, further studies are required to optimize dosing strategies and minimize toxicity., Competing Interests: The authors declare no conflict of interest.

Background: Small-cell lung cancer (SCLC) shows high enhancer of zeste homolog 2 (EZH2) expressions. EZH2-mediated epigenetics promote epithelial-mesenchymal transition (EMT), enhancing invasive and metastatic potential in malignancies. MicroRNAs (miRNAs), small noncoding RNAs, modulate EMT, determining tumor phenotypes. However, the association between miRNAs and EZH2 in SCLC remains to be clarified-we aimed to identify a novel tumorigenic mechanism through miRNAs, EZH2, and EMT in SCLC, leading to future therapeutic applications., Methods: We analyzed EZH2 and E-cadherin expressions in lung cancer cell lines and tumor tissues from 34 SCLC patients and confirmed EZH2 siRNA-mediated EMT inhibition. miRNA expression profiles were compared between EZH2 knockdown SCLC cells and negative control SCLC cells using miRNA array. We identified a target miRNA of EZH2 showing expressional differences in EZH2-knockdown cells and analyzed the impact of the miRNA on EZH2-mediated EMT and tumorigenesis., Results: All SCLC cells showed increased EZH2 and decreased E-cadherin expressions. SCLC tissues had higher EZH2 and lower E-cadherin expressions than other lung cancer tissues. miRNA array revealed that miR-4448 expression increased in EZH2-knockdown SCLC cells. miR-4448 overexpression reduced tumor cell growth and prevented EMT. miR-4448 bound to the 3'UTR of the girdin gene and suppressed its expression, thereby decreasing Akt phosphorylation at Ser473. Attenuated Akt phosphorylation resulted in AMP-activated protein kinase (AMPK) phosphorylation at Thr172 and 183, enhancing EZH2 phosphorylation at Thr311., Conclusion: SCLC characterized high EZH2 expression and promoted EMT, compared with non-small cell lung cancer. miR-4448 inhibited Girdin expression, reducing Akt phosphorylation, and enhancing AMPK and EZH2 phosphorylation. Eventually, miR-4448 prevented EZH2-mediated EMT and tumorigenesis by modulating the Girdin/Akt/AMPK axis in SCLC. miR-4448 might be a potential SCLC inhibitor., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Small cell lung cancer (SCLC) is characterized by rapid development of chemoresistance and poor outcomes. Cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) are widely used in breast cancer and other cancer types. However, the molecular mechanisms of CDK4/6 in SCLC chemoresistance remain poorly understood. Here, Rb1 flox/flox , Trp53 flox/flox , Pten flox/flox (RTP) and Rb1 flox/flox , Trp53 flox/flox , Myc LSL/LSL (RPM) spontaneous SCLC mouse models, SCLC cell line-derived xenograft (CDX) models, and SCLC patient-derived xenograft (PDX) models are established to reveal the potential effects of CDK4/6is on SCLC chemoresistance. In this study, it is found that CDK4/6is palbociclib (PD) or ribociclib (LEE) combined with chemotherapeutic drugs significantly inhibit SCLC tumor growth. Mechanistically, CDK4/6is do not function through the classic Retionblastoma1 (RB) dependent axis in SCLC. CDK4/6is induce impair autophagy through the AMBRA1-lysosome signaling pathway. The upregulated AMBRA1 protein expression leads to CDK6 degradation via autophagy,  and the following TFEB and TFE3 nuclear translocation inhibition leading to the lysosome-related genes levels downregulation. Moreover, it is found that the expression of CDK6 is higher in SCLC tumors than in normal tissue and it is associated with the survival and prognosis of SCLC patients. Finally, these findings demonstrate that combining CDK4/6is with chemotherapy treatment may serve as a potential therapeutic option for SCLC patients., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Patients with small-cell lung cancer (SCLC) have poor prognosis and typically experience only transient benefits from combined immune checkpoint blockade (ICB) and chemotherapy. Here, we show that inhibition of ataxia telangiectasia and rad3 related (ATR), the primary replication stress response activator, induces DNA damage-mediated micronuclei formation in SCLC models. ATR inhibition in SCLC activates the stimulator of interferon genes (STING)-mediated interferon signaling, recruits T cells, and augments the antitumor immune response of programmed death-ligand 1 (PD-L1) blockade in mouse models. We demonstrate that combined ATR and PD-L1 inhibition causes improved antitumor response than PD-L1 alone as the second-line treatment in SCLC. This study shows that targeting ATR up-regulates major histocompatibility class I expression in preclinical models and SCLC clinical samples collected from a first-in-class clinical trial of ATR inhibitor, berzosertib, with topotecan in patients with relapsed SCLC. Targeting ATR represents a transformative vulnerability of SCLC and is a complementary strategy to induce STING-interferon signaling-mediated immunogenicity in SCLC.

Background: Small cell lung cancer (SCLC) is known as recalcitrant cancer with high malignancy and heterogeneity. Immunotherapy has changed the treatment pattern of extensive-disease SCLC (ED-SCLC), but the beneficiary population is limited. Therefore, exploring new therapeutic strategies is an urgent clinical problem to be solved for SCLC. SCLC is characterized by highly active glycolytic metabolism and pyruvate kinase M1 (PKM1) is one of the isozymes of PK, an important rate-limiting enzyme in glycolysis pathway. Previous studies have shown that PKM1 is related to autophagy and drug sensitivity, however, how PKM1 regulates drug sensitivity in SCLC and its mechanism remain unclear. The aim of this study was to investigate the biological functions of PKM1 in SCLC, including its effects on proliferation, migration, autophagy, drug sensitivity, and expression of neuroendocrine (NE)-related markers in SCLC., Methods: Western blot was used to detect the expression level of PKM1 in SCLC cells. PKM1 gene-overexpressed SCLC cell lines were constructed by stable lentivirus transfection. Proliferation of cells and drug sensitivity were detected by MTT, and migration ability of cells was determined by Transwell. The level of autophagy was detected by flow cytometry. Western blot was used to determine the expression levels of NE-related proteins., Results: PKM1 was differentially expressed among various SCLC cell lines, and was lower in H1092 cells (P<0.01). Compared with the control group, there was no significant difference in proliferation level of PKM1 overexpressing H1092 cell, but the migration ability was significantly increased (P<0.001), the drug sensitivity was reduced, and the level of autophagy was inhibited (P<0.001). Additionally, overexpression of PKM1 could upregulate the expression of non-neuroendocrine (non-NE)-related proteins (P<0.01) and decrease the expression of NE-related proteins (P<0.01)., Conclusions: PKM1 was differentially expressed in SCLC cell lines, and high expression of PKM1 did not affect the proliferation, but affected the migration of SCLC cells. PKM1 might affect drug sensitivity by inhibiting autophagy and regulating the expression of NE markers. These results provide a theoretical basis for exploring the role of PKM1 in SCLC.

Unlike other cancers with widespread screening (breast, colorectal, cervical, prostate, and skin), lung nodule biopsies for positive screenings have higher morbidity with clinical complications. Development of non-invasive diagnostic biomarkers could thereby significantly enhance lung cancer management for at-risk patients. Here, we leverage Mendelian Randomization (MR) to investigate the plasma proteome and metabolome for potential biomarkers relevant to lung cancer. Utilizing bidirectional MR and co-localization analyses, we identify novel associations, highlighting inverse relationships between plasma proteins SFTPB and KDELC2 in lung adenocarcinoma (LUAD) and positive associations of TCL1A with lung squamous cell carcinoma (LUSC) and CNTN1 with small cell lung cancer (SCLC). Additionally, our work reveals significant negative correlations between metabolites such as theobromine and paraxanthine, along with paraxanthine-related ratios, in both LUAD and LUSC. Conversely, positive correlations are found in caffeine/paraxanthine and arachidonate (20:4n6)/paraxanthine ratios with these cancer types. Through single-cell sequencing data of normal lung tissue, we further explore the role of lung tissue-specific protein SFTPB in carcinogenesis. These findings offer new insights into lung cancer etiology, potentially guiding the development of diagnostic biomarkers and therapeutic approaches., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Small cell lung cancer (SCLC) is a very aggressive tumor. Abnormal expression of BUB1 has been reported in several cancer types, wherein it plays a range of functional roles. This work aimed to elucidate the functional significance and molecular impacts of BUB1 in SCLC. It was found that SCLC cell lines exhibited significant BUB1 upregulation relative to control bronchial cells using data from the Gene Expression Omnibus (GEO) database and verified by immunohistochemical staining. BUB1 was also found to promote the proliferative, migratory, invasive activity of SCLC cells, as shown by CCK-8, 3D migration wound-healing, and Transwell assays, as well as flow cytometry. Additionally, it was found that BUB1 silencing enhanced E-cadherin expression while suppressing N-cadherin, Vimentin, ZEB-1, and Snail levels, as shown by Western immunoblotting. The loss of BUB1 also reduced p-AKT and p-mTOR levels without altering total AKT or mTOR protein levels. In conclusion, BUB1 functions as an oncogenic promoter in SCLC, potentially regulating the epithelial-mesenchymal transition by activation of AKT/mTOR signaling., (© 2024. The Author(s).)

Small cell lung cancer (SCLC) is an epithelial neuroendocrine form of lung cancer for which survival rates remain dismal and new therapeutic approaches are greatly needed. Key biological features of SCLC tumors include fast growth and widespread metastasis, as well as rapid resistance to treatment. Similar to pulmonary neuroendocrine cells, SCLC cells have traits of both hormone-producing cells and neurons. In this study, we specifically discuss the neuronal features of SCLC. We consider how neuronal G protein-coupled receptors and other neuronal molecules on the surface of SCLC cells can contribute to the growth of SCLC tumors and serve as therapeutic targets in SCLC. We also review recent evidence for the role of neuronal programs expressed by SCLC cells in the fast proliferation, migration, and metastasis of these cells. We further highlight how these neuronal programs may be particularly relevant for the development of brain metastases and how they can assist SCLC cells to functionally interact with neurons and astrocytes. A greater understanding of the molecular and cellular neuronal features of SCLC is likely to uncover new vulnerabilities in SCLC cells, which may help develop novel therapeutic approaches. More generally, the epithelial-to-neuronal transition observed during tumor progression in SCLC and other cancer types can contribute significantly to tumor development and response to therapy., (©2024 American Association for Cancer Research.)

Lineage plasticity in small cell lung carcinoma (SCLC) causes therapeutic difficulties. This study aimed to investigate the pathological findings of plasticity in SCLC, focusing on combined SCLC, and elucidate the involvement of YAP1 and other transcription factors. We analysed 100 surgically resected SCLCs through detailed morphological observations and immunohistochemistry for YAP1 and other transcription factors. Component-by-component next-generation sequencing (n = 15 pairs) and immunohistochemistry (n = 35 pairs) were performed on the combined SCLCs. Compared with pure SCLCs (n = 65), combined SCLCs (n = 35) showed a significantly larger size, higher expression of NEUROD1, and higher frequency of double-positive transcription factors (p = 0.0009, 0.04, and 0.019, respectively). Notably, 34% of the combined SCLCs showed morphological mosaic patterns with unclear boundaries between the SCLC and its partner. Combined SCLCs not only had unique histotypes as partners but also represented different lineage plasticity within the partner. NEUROD1-dominant combined SCLCs had a significantly higher proportion of adenocarcinomas as partners, whereas POU2F3-dominant combined SCLCs had a significantly higher proportion of squamous cell carcinomas as partners (p = 0.006 and p = 0.0006, respectively). YAP1 expression in SCLC components was found in 80% of combined SCLCs and 62% of pure SCLCs, often showing mosaic-like expression. Among the combined SCLCs with component-specific analysis, the identical TP53 mutation was found in 10 pairs, and the identical Rb1 abnormality was found in 2 pairs. On immunohistochemistry, the same abnormal p53 pattern was found in 34 pairs, and Rb1 loss was found in 24 pairs. In conclusion, combined SCLC shows a variety of pathological plasticity. Although combined SCLC is more plastic than pure SCLC, pure SCLC is also a phenotypically plastic tumour. The morphological mosaic pattern and YAP1 mosaic-like expression may represent ongoing lineage plasticity. This study also identified the relationship between transcription factors and partners in combined SCLC. Transcription factors may be involved in differentiating specific cell lineages beyond just 'neuroendocrine'., (© 2024 The Author(s). The Journal of Pathology: Clinical Research published by The Pathological Society of Great Britain and Ireland and John Wiley & Sons Ltd.)

Background/aim: Small-cell lung cancer (SCLC) is noted for its high proliferative rate, and while treatable, relapse is common. SCLC is known to potentially express somatostatin receptors (SSTRs). Somatostatin possesses antineoplastic activity through cell-cycle arrest and apoptosis, and angiogenesis inhibition. SSTRs, thus, serve as potential anticancer targets for somatostatin analogue therapies. The aim of the study was to determine the expression rate of SSTR subtypes 1, 2 and 3 in SCLC using immunohistochemistry, and potential predictors of such rates., Materials and Methods: A total of 147 human, SCLC paraffin-embedded tissue microarrays with corresponding patient age, sex, TNM staging, and disease stage were utilized. Immunohistochemical analysis was performed using anti-SSTR 1, 2 and 3 antibodies, each calibrated using healthy human pancreatic islets as positive controls. Array slides were counterstained with hematoxylin and scored based on stain intensity and percentage of stained cells., Results: No SCLC samples expressed SSTR 1, whereas SSTR 2 and 3 were expressed in 29.4% and 4.35% of cases respectively. While females had higher expression levels of SSTR 2/3, and there was a trend of decreased SSTR 2 expression with increased age, results were not statistically significant. No correlation between disease stage and SSTR expression was found. Co-expression of both SSTR2 and 3 occurred in 5.3% of patients., Conclusion: Immunohisto-chemistry is an efficient screening tool to reveal optimum SCLC patients for somatostatin analogue therapy. Whilst there currently exist no accepted norm or predictors of SSTR expression levels in SCLC patients, this study contributes insight into the receptors' varied expression., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Small-cell lung cancer (SCLC) is the most aggressive and lethal type of lung cancer, characterized by limited treatment options, early and frequent metastasis. However, the determinants of metastasis in SCLC are poorly defined. Here, we show that estrogen-related receptor gamma (ERRγ) is overexpressed in metastatic SCLC tumors, and is positively associated with SCLC progression. ERRγ functions as an essential activator of extracellular matrix (ECM) remodeling and cell adhesion, two critical steps in metastasis, by directly regulating the expression of major genes involved in these processes. Genetic and pharmacological inhibition of ERRγ markedly reduces collagen production, cell-matrix adhesion, microfilament production, and eventually blocks SCLC cell invasion and tumor metastasis. Notably, ERRγ antagonists significantly suppressed tumor growth and metastasis and restored SCLC vulnerability to chemotherapy in multiple cell-derived and patient-derived xenograft models. Taken together, these findings establish ERRγ as an attractive target for metastatic SCLC and provide a potential pharmacological strategy for treating this lethal disease., (© 2024. The Author(s).)

Background: Small cell lung cancer (SCLC) is the most aggressive type of lung cancer. The overall survival has not improved significantly over the last decades because no major therapeutic breakthroughs have been achieved for over 15 years., Methods: We analyzed a genome-wide loss-of-function screening database to identify vulnerabilities in SCLC for the development of urgently needed novel therapies., Results: We identified SKP2 (encoding S-phase kinase-associated protein 2) and CKS1B (encoding CDC28 protein kinase regulatory subunit 1B) as the two most essential genes in that order in SCLC. Notably, SKP2 and CKS1B comprise the p27 binding pocket of the E3 ubiquitin ligase SCF SKP2 complex. Immunohistochemistry on tissue microarrays revealed that SKP2 was expressed in >95% of samples at substantially higher levels than that observed for commonly used neuroendocrine markers. As expected, SCLC cell lines were sensitive to SKP2 inhibition. Furthermore, SKP2 or CKS1B knockdown induced apoptosis in RB1 mutant cells, whereas it induced senescence in RB1 wild-type cells., Conclusion: Although the mechanism underlying SKP2 knockdown-induced growth inhibition differs between RB1-wild-type and -mutant SCLC, SKP2 can be considered a novel therapeutic target for patients with SCLC regardless of the RB1 mutation status. Our findings indicate that SKP2 is a potential novel clinical diagnostic marker and therapeutic target in SCLC., Competing Interests: Declaration of competing interest Ken Tajima received research funding from Novartis. Kazuhisa Takahashi received research funding from Chugai Pharm, MSD, Ono Pharm, and Bristol-Myers Squibb. Additionally, Kazuhisa Takahashi acknowledges donations from Eli Lilly Japan, Teijin Pharm, Chugai Pharm, Nippon Boehringer Ingelheim, Kyorin Pharm, Taiho Pharm, and Sanofi. The other authors have no conflicts of interest., (Copyright © 2024 [The Author]. Published by Elsevier B.V. All rights reserved.)

Small cell lung cancer (SCLC) is a recalcitrant cancer of neuroendocrine (NE) origin. Changes in therapeutic approaches against SCLC have been lacking over the decades. Here, we use preclinical models to identify a new therapeutic vulnerability in SCLC consisting of the targetable Jumonji lysine demethylase (KDM) family. We show that Jumonji demethylase inhibitors block malignant growth and that etoposide-resistant SCLC cell lines are particularly sensitive to Jumonji inhibition. Mechanistically, small molecule-mediated inhibition of Jumonji KDMs activates endoplasmic reticulum (ER) stress genes, upregulates ER stress signaling, and triggers apoptotic cell death. Furthermore, Jumonji inhibitors decrease protein levels of SCLC NE markers INSM1 and Secretogranin-3 and of driver transcription factors ASCL1 and NEUROD1. Genetic knockdown of KDM4A, a Jumonji demethylase highly expressed in SCLC and a known regulator of ER stress genes, induces ER stress response genes, decreases INSM1, Secretogranin-3, and NEUROD1 and inhibits proliferation of SCLC in vitro and in vivo. Lastly, we demonstrate that two different small molecule Jumonji KDM inhibitors (pan-inhibitor JIB-04 and KDM4 inhibitor SD70) block the growth of SCLC tumor xenografts in vivo. Our study highlights the translational potential of Jumonji KDM inhibitors against SCLC, a clinically feasible approach in light of recently opened clinical trials evaluating this drug class, and establishes KDM4A as a relevant target across SCLC subtypes., (© 2024. The Author(s).)

Objective: Our purpose was to investigate the clinicopathological diagnostic value of immunohistochemical antibody for insulinoma-associated protein 1 (INSM1) in biopsy specimens of SCLC. Methods: Biopsy specimens of SCLC diagnosed at the pathology department of Tangshan Gongren Hospital from January 2022 to June 2023 were selected. INSM1 expression was detected and compared with conventional neuroendocrine markers synaptophysin (SYP), chromogranin A (CHGA), and CD56 regarding expression sensitivity and specificity. Results: The sensitivity of INSM1 expression was significantly higher than that of CHGA (95% vs 50%, P  = .000), but there was no statistically significant difference in the specificity of INSM1, SYP, CHGA, and CD56 expression (100% vs 94% vs 98% vs 92%, respectively, P  = .241, 1.000, .126). Conclusions: INSM1 antibody shows high sensitivity and specificity in the expression of SCLC and serves as a reliable immunohistochemical marker in the clinicopathological diagnosis of SCLC in biopsy specimens., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Thioredoxin Reductase (TrxR) functions to recycle thioredoxin (Trx) during hydroperoxide metabolism mediated by peroxiredoxins and is currently being targeted using the FDA-approved anti-rheumatic drug, auranofin (AF), to selectively sensitize cancer cells to therapy. AF treatment decreased TrxR activity and clonogenic survival in small cell lung cancer (SCLC) cell lines (DMS273 and DMS53) as well as the H727 atypical lung carcinoid cell line. AF treatment also significantly sensitized DMS273 and H727 cell lines in vitro to sorafenib, an FDA-approved multi-kinase inhibitor that depleted intracellular glutathione (GSH). The pharmacokinetic, pharmacodynamic, and safety profile of AF was examined in nude mice with DMS273 xenografts administered AF intraperitoneally at 2 mg/kg or 4 mg/kg (IP) once (QD) or twice daily (BID) for 1-5 d. Plasma levels of AF were 10-20 μM (determined by mass spectrometry of gold), and the optimal inhibition of TrxR activity was obtained at 4 mg/kg once daily, with no effect on glutathione peroxidase 1 activity. This AF treatment extended for 14 d, inhibited TrxR (>75%), and resulted in a significant prolongation of median overall survival from 19 to 23 d ( p  = .04, N  = 30 controls, 28 AF). In this experiment, there were no observed changes in animal bodyweight, complete blood counts (CBCs), bone marrow toxicity, blood urea nitrogen, or creatinine. These results support the hypothesis that AF effectively inhibits TrxR both in vitro and in vivo in SCLC, sensitizes NETs and SCLC to sorafenib, and could be repurposed as an adjuvant therapy with targeted agents that induce disruptions in thiol metabolism.

Small cell lung cancer (SCLC) is a recalcitrant malignancy with dismal prognosis due to rapid relapse after an initial treatment response. More effective treatments for SCLC are desperately needed. Our previous studies showed that cell migration-inducing hyaluronan binding protein (CEMIP) functionally promotes SCLC cell proliferation and metastasis. In this study, we investigated whether and how CEMIP regulates the chemosensitivity of SCLC. Through the GDSC database, we found that CEMIP expression levels were positively correlated with the IC 50 values of several commonly used chemotherapeutic drugs in SCLC cells (cisplatin, gemcitabine, 5-fluorouracil and cyclophosphamide). We demonstrated that overexpression or knockdown of CEMIP in SCLC cells resulted in a notable increase or reduction in the IC 50 value of cisplatin or etoposide, respectively. We further revealed that CEMIP functions as an adaptor protein in SCLC cells to interact with SRC and YAP through the 1-177 aa domain and 820-1361 aa domain, respectively, allowing the autophosphorylation of Y416 and activation of SRC, thus facilitating the interaction between YAP and activated SRC, and resulting in increased phosphorylation of Y357, protein stability, nuclear accumulation and transcriptional activation of YAP. Overexpressing SRC or YAP counteracted the CEMIP knockdown-mediated increase in the sensitivity of SCLC cells to cisplatin and etoposide. The combination of the SRC inhibitor dasatinib or the YAP inhibitor verteporfin and cisplatin/etoposide (EP regimen) displayed excellent synergistic antitumor effects on SCLC both in vitro and in vivo. This study demonstrated that targeted therapy against the CEMIP/SRC/YAP complex is a potential strategy for SCLC and provides a rationale for the development of future clinical trials with translational prospects., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.)

Patients with small-cell lung cancer (SCLC) are in dire need of more effective therapeutic options. Frequent disruption of the G1 checkpoint in SCLC cells creates a dependency on the G2/M checkpoint to maintain genomic integrity. Indeed, in pre-clinical models, inhibiting the G2/M checkpoint kinase WEE1 shows promise in inhibiting SCLC growth. However, toxicity and acquired resistance limit the clinical effectiveness of this strategy. Here, using CRISPR-Cas9 knockout screens in vitro and in vivo, we identified multiple factors influencing the response of SCLC cells to the WEE1 kinase inhibitor AZD1775, including the GCN2 kinase and other members of its signaling pathway. Rapid activation of GCN2 upon AZD1775 treatment triggers a stress response in SCLC cells. Pharmacological or genetic activation of the GCN2 pathway enhances cancer cell killing by AZD1775. Thus, activation of the GCN2 pathway represents a promising strategy to increase the efficacy of WEE1 inhibitors in SCLC., Competing Interests: Declaration of interests J.S. has equity in and is an advisor for DISCO Pharmaceuticals., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Rationale: Positron Emission Tomography (PET) using the somatostatin receptor 2 (SSTR2)-antagonist satoreotide trizoxetan ( 68 Ga-SSO120) is a novel, promising imaging modality for small-cell lung cancer (SCLC), which holds potential for theranostic applications. This study aims to correlate uptake in PET imaging with SSTR2 expression in immunohistochemistry (IHC) and to assess the prognostic value of 68 Ga-SSO120 PET at initial staging of patients with SCLC. Methods: We analyzed patients who underwent 68 Ga-SSO120 PET/CT during initial diagnostic workup of SCLC as part of institutional standard-of-care. SSTR2 expression in IHC was evaluated on a 4-level scale and correlated with normalized standardized uptake values and tumor-to-liver ratios (SUV max and TLR peak ) in 68 Ga-SSO120 PET on a lesion level. Highest lesion SUV max /TLR peak per patient, SSTR2 score in IHC, M status according to TNM classification, and other parameters were analyzed for association with overall survival (OS) and time to treatment failure (TTF) by univariate, multivariate (cut-off values were identified on data for best separation), and stratified Cox regression. Results: We included 54 patients (24 men/30 women, median age 65 years, 21 M0/33 M1 according to TNM classification). In 43 patients with available surplus tumor tissue samples, hottest lesion SUV max /TLR peak showed a significant correlation with the level of SSTR2-expression by tumor cells in IHC (Spearman's rho 0.86/0.81, both p < 0.001; ANOVA p < 0.001). High SSTR2 expression in IHC, 68 Ga-SSO120 SUV max and TLR peak of the hottest lesion per patient, whole-body TLR mean , MTV, TLG, M status, and serum LDH showed a significant association with inferior TTF/OS in univariate analysis. In separate multivariate Cox regression (including sex, age, M stage, and LDH) higher hottest-lesion TLR peak showed a significant association with shorter OS (HR = 0.26, 95%CI: 0.08-0.84, p = 0.02) and SSTR2 expression in IHC with significantly shorter TTF (HR = 0.24, 95%CI: 0.08-0.71, p = 0.001) and OS (HR = 0.22, 95%CI: 0.06-0.84, p = 0.03). In total, 12 patients (22.2%) showed low (< 1), 21 (38.9%) intermediate (≥ 1 but < 2), 14 (25.9%) high (≥ 2 but < 5), and 7 (13.0%) very high (≥ 5) whole-body mean TLR mean . Conclusion: In patients with SCLC, SSTR2 expression assessed by 68 Ga-SSO120 PET and by IHC were closely correlated and associated with shorter survival. More than 75% of patients showed higher whole-body 68 Ga-SSO120 tumor uptake than liver uptake and almost 40% high or very high uptake, possibly paving the way towards theranostic applications., Competing Interests: Competing Interests: Filiz Oezkan received personal fees from Sanofi Aventis, Janssen, DeciBio, ERBE and Genentech/Roche Ltd.; program funding to the institution was received from Olympus, Astrazeneca, ERBE and Janssen, all outside the submitted work. Lale Umutlu is a Speaker / Advisory Board Member for Bayer Healthcare and Siemens Healthcare and received research grants from Siemens Healthcare outside the submitted work. Rainer Hamacher was supported by the Clinician Scientist Program of the University Medicine Essen Clinician Scientist Academy (UMEA; Faculty of Medicine and Deutsche Forschungsgemeinschaft [DFG]); reports travel grants from Lilly, Novartis, and PharmaMar; and reports personal fees from Lilly and PharmaMar outside the submitted work. Jens Siveke is supported by German Cancer Aid (grant 70112505, PIPAC; grant 70113834, PREDICT-PACA), the Wilhelm-Sander Foundation (grant 2019.008.1), the DFG through grant SI1549/3-1 (Clinical Research Unit KFO337) and SI1549/4-1, and the Federal Ministry of Education and Research (BMBF; SATURN3 consortium); receives honoraria as a consultant or for continuing medical education presentations from AstraZeneca, Bayer, Immunocore, Roche, and Servier; receives research funding (to the institution) from Bristol Myers Squibb, Celgene, and Roche; and holds ownership and serves on the board of directors of Pharma15—all outside the submitted work. Wolfgang Fendler reports fees from SOFIE Biosciences (research funding), Janssen (consultant, speaker), Calyx (consultant, image review), Bayer (consultant, speaker, research funding), Novartis (speaker, consultant), Telix (speaker), GE Healthcare (speaker), Eczacıbaşı Monrol (speaker), Abx (speaker), Amgen (speaker), and Urotrials, all outside the submitted work. Marcel Wiesweg reports honoraria and advisory role from Amgen, AstraZeneca, Daiichi Sankyo, GlaxoSmithKline, Janssen, Novartis, Pfizer, Roche, Takeda, and research funding from Bristol-Myers Squibb, Takeda outside the submitted work. Ken Herrmann reports personal fees from Bayer, personal fees and other from Sofie Biosciences, personal fees from SIRTEX, non-financial support from ABX, personal fees from Adacap, personal fees from Curium, personal fees from Endocyte, grants and personal fees from BTG, personal fees from IPSEN, personal fees from Siemens Healthineers, personal fees from GE Healthcare, personal fees from Amgen, personal fees from Novartis, personal fees from ymabs, personal fees from Aktis Oncology, personal fees from Theragnostics, personal fees from Pharma15, outside the submitted work. Martin Schuler reports personal fees as a consultant from Amgen, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, GlaxoSmithKline, Janssen, Merck Serono, Novartis, Roche, Sanofi, and Takeda; honoraria for continuing medical education presentations from Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Janssen, MSD, and Novartis; and research funding (to the institution) from AstraZeneca and Bristol Myers Squibb, all outside the submitted work. Hubertus Hautzel reports personal fees from Roche and Urenco, and other fees from Pari, Roche and Urenco, outside the submitted work. David Kersting reports speaker honoraria from Pfizer and Novartis outside the submitted work. A research grant from Pfizer outside the submitted work and funding by the German Research Foundation (DFG, KE2933/1-1), outside the submitted work., (© The author(s).)

Small cell lung cancer (SCLC), one of the histological subtypes of lung cancer, is characterized by high proliferation, early metastasis, susceptibility to drug resistance and recurrence. For several years, SCLC has always been regarded as a homogeneous disease, treated with a unified radiotherapy and chemotherapy strategy. Despite significant early therapeutic effects, drug resistance and recurrence occur quickly, and there is a lack of satisfactory treatment results, which may be due to insufficient understanding of the tumor heterogeneity of SCLC at present. Recently, the concept of SCLC molecular subtype based on the definition of relatively high expression of lineage transcription factors has been proposed in preclinical studies. This article mainly elaborates on the current status and latest findings of SCLC molecular subtype, emphasizing the potential problems that molecular typing may encounter in clinical practice, aiming to promote understanding of the research progress of molecular subtype in SCLC.
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Background: Exosomes play a crucial role in promoting tumor progression, dissemination, and resistance to treatment. These extracellular vesicles hold promise as valuable indicators for cancer detection. Our investigation focuses on exploring the significance and clinical relevance of exosomal miRNAs in small cell lung cancer (SCLC)., Methods: Serum exosomes were isolated from both SCLC patients and healthy controls, and subjected to exosomal miRNA sequencing analysis. Mimics and inhibitors were employed to investigate the function of exosomal miR-1128-5p in cell migration and proliferation, both in vitro and in vivo. Western blot and luciferase assay were utilized to identify the interaction between miR-1228-5p and dual specificity phosphatase 22 (DUSP22)., Results: Exosomal miRNA sequencing analysis revealed enrichment of specific miRNAs in SCLC compared to healthy controls. Circulating miR-1228-5p was upregulated in SCLC patients, associated with advanced stages, suggesting its potential oncogenic role. In vitro, miR-1228-5p expression was significantly higher in SCLC cells than in normal cells. SCLC cell-derived exosomes contained elevated levels of miR-1228-5p, facilitating its entry into co-cultured cells. Notably, migration and proliferation induced by SCLC exosomes were mainly mediated by miR-1228-5p. In vivo experiments confirmed these findings. Western blot analysis demonstrated miR-1228-5p's regulation of DUSP22 expression, and luciferase reporter assay validated DUSP22 as a direct target gene. Overexpressing DUSP22 counteracted miR-1228-5p's promotion of SCLC cell proliferation and migration., Conclusions: Collectively, our results suggest that exosomes play a role in facilitating cancer growth and metastasis by delivering miR-1228-5p. Moreover, circulating exosomal miR-1228-5p may serve as a potential marker for SCLC diagnosis and prognosis., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Small cell lung cancers (SCLCs) are composed of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLCs, ∼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes as top dependencies specific to POU2F3-positive SCLC. Notably, chemical disruption of mSWI/SNF ATPase activity attenuates proliferation of all POU2F3-positive SCLCs, while disruption of non-canonical BAF (ncBAF) via BRD9 degradation is effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF targets to and maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, clinical-grade pharmacologic disruption of SMARCA4/2 ATPases and BRD9 decreases POU2F3-SCLC tumor growth and increases survival in vivo. These results demonstrate mSWI/SNF-mediated governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for POU2F3-positive SCLCs., Competing Interests: Declaration of interests M.G.O. reports grants from Eli Lilly, Takeda, Novartis, BMS, and Circle Pharma. C.K. is the Scientific Founder, Scientific Advisor to the Board of Directors, Scientific Advisory Board member, shareholder, and consultant for Foghorn Therapeutics, Inc. (Cambridge, MA), serves on the Scientific Advisory Boards of Nereid Therapeutics, Nested Therapeutics, and and Fibrogen, Inc. and is a consultant for Cell Signaling Technologies, Accent Therapeutics, and Google Ventures. C.K. is also a member of the Molecular Cell and Cell Chemical Biology Editorial Boards. B.J.D. has received consulting fees from AstraZeneca, Sonata Therapeutics and Dialectic Therapeutics. C.R.V. has received consulting fees from Flare Therapeutics, Roivant Sciences and C4 Therapeutics; has served on the advisory boards of KSQ Therapeutics, Syros Pharmaceuticals and Treeline Biosciences; has received research funding from Boehringer-Ingelheim and Treeline Biosciences; and owns stock in Treeline Biosciences., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The POU2F3-POU2AF2/3 transcription factor complex is the master regulator of the tuft cell lineage and tuft cell-like small cell lung cancer (SCLC). Here, we identify a specific dependence of the POU2F3 molecular subtype of SCLC (SCLC-P) on the activity of the mammalian switch/sucrose non-fermentable (mSWI/SNF) chromatin remodeling complex. Treatment of SCLC-P cells with a proteolysis targeting chimera (PROTAC) degrader of mSWI/SNF ATPases evicts POU2F3 and its coactivators from chromatin and attenuates downstream signaling. B cell malignancies which are dependent on the POU2F1/2 cofactor, POU2AF1, are also sensitive to mSWI/SNF ATPase degraders, with treatment leading to chromatin eviction of POU2AF1 and IRF4 and decreased IRF4 signaling in multiple myeloma cells. An orally bioavailable mSWI/SNF ATPase degrader significantly inhibits tumor growth in preclinical models of SCLC-P and multiple myeloma without signs of toxicity. This study suggests that POU2F-POU2AF-driven malignancies have an intrinsic dependence on the mSWI/SNF complex, representing a therapeutic vulnerability., Competing Interests: Declaration of interests A.M.C. serves on the clinical advisory board of Aurigene Oncology Limited. C.A., S.S., and M.R. are employees of Aurigene Oncology Limited. C.R.V. has received consulting fees from Flare Therapeutics, Roivant Sciences, and C4 Therapeutics; he has served on the advisory boards of KSQ Therapeutics, Syros Pharmaceuticals, and Treeline Biosciences. C.R.V. has also received research funding from Boehringer-Ingelheim and Treeline Biosciences and owns stock in Treeline Biosciences. Aurigene Oncology Limited has filed patent applications on AU-15330 and AU-24118. C.M.R. has consulted regarding oncology drug development with AbbVie, Amgen, Astra Zeneca, D2G, Daiichi Sankyo, Epizyme, Genentech/Roche, Ipsen, Jazz, Kowa, Lilly, Merck, and Syros. C.M.R. serves on the scientific advisory boards of Auron, Bridge Medicines, DISCO, Earli, and Harpoon Therapeutics., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

In Cancer Cell, Bolomsky et al., Duplaquet et al., and He et al. identify cancers that are dependent on the BAF chromatin remodeling complex, specifically IRF4-driven multiple myeloma and POU2F3-subtype small cell lung cancer, highlighting potential therapeutic applications for BAF complex inhibitors/degraders., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Few effective treatments are available for small cell lung cancer (SCLC), indicating the need to explore new therapeutic options. Here, we focus on an antibody-drug conjugate (ADC) targeting the L1 cell adhesion molecule (L1CAM). Several publicly available databases reveal that (1) L1CAM is expressed at higher levels in SCLC cell lines and tissues than in those of lung adenocarcinoma and (2) the expression levels of L1CAM are slightly higher in SCLC tissues than in adjacent normal tissues. We conducted a series of in vitro experiments using an anti-L1CAM monoclonal antibody (termed HSL175, developed in-house) and the recombinant protein DT3C, which consists of diphtheria toxin lacking the receptor-binding domain but containing the C1, C2, and C3 domains of streptococcal protein G. Our HSL175-DT3C conjugates theoretically kill cells only when the conjugates are internalized by the target (L1CAM-positive) cells through antigen-antibody interaction. The conjugates (an ADC analog) were effective against two SCLC-N (NEUROD1 dominant) cell lines, Lu-135 and STC-1, resulting in decreased viability. In addition, L1CAM silencing rendered the two cell lines resistant to HSL175-DT3C conjugates. These findings suggest that an ADC consisting of a humanized monoclonal antibody based on HSL175 and a potent anticancer drug would be effective against SCLC-N cells.

Small-cell lung cancer (SCLC) accounts for nearly 15% of all lung cancers. Although patients respond to first-line therapy readily, rapid relapse is inevitable, with few treatment options in the second-line setting. Here, we describe SCLC cell lines harboring amplification of MYC and MYCN but not MYCL1 or non-amplified MYC cell lines exhibit superior sensitivity to treatment with the pan-BET bromodomain protein inhibitor mivebresib (ABBV075). Silencing MYC and MYCN partially rescued SCLC cell lines harboring these respective amplifications from the antiproliferative effects of mivebresib. Further characterization of genome-wide binding of MYC, MYCN, and MYCL1 uncovered unique enhancer and epigenetic preferences. Implications: Our study suggests that chromatin landscapes can establish cell states with unique gene expression programs, conveying sensitivity to epigenetic inhibitors such as mivebresib., (©2024 The Authors; Published by the American Association for Cancer Research.)

Introduction: Recent insights regarding mechanisms mediating stemness, heterogeneity, and metastatic potential of lung cancers have yet to be fully translated to effective regimens for the treatment of these malignancies. This study sought to identify novel targets for lung cancer therapy., Methods: Transcriptomes and DNA methylomes of 14 SCLC and 10 NSCLC lines were compared with normal human small airway epithelial cells (SAECs) and induced pluripotent stem cell (iPSC) clones derived from SAEC. SCLC lines, lung iPSC (Lu-iPSC), and SAEC were further evaluated by DNase I hypersensitive site sequencing (DHS-seq). Changes in chromatin accessibility and depths of transcription factor (TF) footprints were quantified using Bivariate analysis of Genomic Footprint. Standard techniques were used to evaluate growth, tumorigenicity, and changes in transcriptomes and glucose metabolism of SCLC cells after NFIC knockdown and to evaluate NFIC expression in SCLC cells after exposure to BET inhibitors., Results: Considerable commonality of transcriptomes and DNA methylomes was observed between Lu-iPSC and SCLC; however, this analysis was uninformative regarding pathways unique to lung cancer. Linking results of DHS-seq to RNA sequencing enabled identification of networks not previously associated with SCLC. When combined with footprint depth, NFIC, a transcription factor not previously associated with SCLC, had the highest score of occupancy at open chromatin sites. Knockdown of NFIC impaired glucose metabolism, decreased stemness, and inhibited growth of SCLC cells in vitro and in vivo. ChIP-seq analysis identified numerous sites occupied by BRD4 in the NFIC promoter region. Knockdown of BRD4 or treatment with Bromodomain and extra-terminal domain (BET) inhibitors (BETis) markedly reduced NFIC expression in SCLC cells and SCLC PDX models. Approximately 8% of genes down-regulated by BETi treatment were repressed by NFIC knockdown in SCLC, whereas 34% of genes repressed after NFIC knockdown were also down-regulated in SCLC cells after BETi treatment., Conclusions: NFIC is a key TF and possible mediator of transcriptional regulation by BET family proteins in SCLC. Our findings highlight the potential of genome-wide chromatin accessibility analysis for elucidating mechanisms of pulmonary carcinogenesis and identifying novel targets for lung cancer therapy., Competing Interests: Disclosure No authors have conflicts of interest to disclose., (Copyright © 2024. Published by Elsevier Inc.)

Objectives: To identify biomarkers that can discriminated small cell lung cancer (SCLC) from non-SCLC (NSCLC), and explore their association with the prognosis of SCLC under chemoradiotherapy., Methods: The GSE40275 dataset was used to identify potential targets in SCLC. There were 196 patients of lung cancer (LC) in cohort 1 of this study. MTHFD1 levels in tissues were determined by immunohistochemistry assay in cohort 1. Lung cancer patients who were all underwent local chemoradiotherapy (CRT) were included in cohort 2, and the association of MTHFD1 levels with CRT treatment outcome were determined in cohort 2. Cell experiments were used to determine the function of MTHFD1 on the radio-sensitivity of SCLC and NSCLC cells., Results: The MTHFD1 levels in LC tissues were increased, and could discriminate SCLC from both lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD). Small cell lung cancer patients with MTHFD1 high phenotype had a poorer prognosis after CRT treatment, whereas no significant correlation was found between MTHFD1 levels and prognosis in LUSC and LUAD group. Cell experiments demonstrated that overexpression of MTHFD1 increases radio-resistance in both SCLC and NSCLC in vitro., Conclusion: MTHFD1 expressions might be a novel specifically prognostic biomarker for SCLC and the CRT treatment outcome., (Copyright: © Saudi Medical Journal.)

We have previously demonstrated that the vasopressin type 2 receptor (AVPR2) antagonist tolvaptan reduces cell proliferation and invasion and triggers apoptosis in different human cancer cell lines. To study this effect in vivo, a xenograft model of small cell lung cancer was developed in Fox1 nu/nu nude mice through the subcutaneous inoculation of H69 cells, which express AVPR2. One group of mice (n = 5) was treated with tolvaptan for 60 days, whereas one group (n = 5) served as the control. A reduced growth was observed in the tolvaptan group in which the mean tumor volume was significantly smaller on day 60 compared to the control group. In the latter group, a significantly lower survival was observed. The analysis of excised tumors revealed that tolvaptan effectively inhibited the cAMP/PKA and PI3K/AKT signaling pathways. The expression of the proliferative marker proliferating cell nuclear antigen (PCNA) was significantly lower in tumors excised from tolvaptan-treated mice, whereas the expression levels of the apoptotic marker caspase-3 were higher than those in control animals. Furthermore, tumor vascularization was significantly lower in the tolvaptan group. Overall, these findings suggest that tolvaptan counteracts tumor progression in vivo and, if confirmed, might indicate a possible role of this molecule as an adjuvant in anticancer strategies.

A remarkable cancer-related role of zinc finger protein 367 (ZNF367) has been demonstrated in multiple malignancies. However, whether ZNF367 has a role in small-cell lung cancer (SCLC) remains unexplored. The purpose of this work was to explore the potential role and mechanism of ZNF367 in SCLC. In silico analysis using the Gene Expression Omnibus (GEO) dataset revealed high levels of the ZNF367 transcript in SCLC. Examination of clinical tissues confirmed the significant abundance of ZNF367 in SCLC tissues compared with adjacent non-malignant tissues. The genetic depletion of ZNF367 in SCLC cells led to remarkable alterations in cell proliferation, the cell cycle, colony formation and chemosensitivity. Mechanistically, ZNF367 was shown to regulate the activation of yes-associated protein (YAP) associated with the up-regulation of phosphorylated large tumour suppressor kinase 2 (LATS2). Further investigation revealed that ZNF367 affected the LATS2-YAP cascade by regulating the expression of citron kinase (CIT). Re-expression of constitutively active YAP diminished the tumour-inhibiting function of ZNF367 depletion. Xenograft experiments confirmed the tumour-inhibiting effect of ZNF367 depletion in vivo. In summary, our results demonstrate that the inhibition of ZNF367 displays anticancer effects in SCLC by inhibiting YAP activation, suggesting it as a potential druggable oncogenic target., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

PLK1 is currently at the forefront of mitotic research and has emerged as a potential target for small cell lung cancer (SCLC) therapy. However, the factors influencing the efficacy of PLK1 inhibitors remain unclear. Herein, BRCA1 was identified as a key factor affecting the response of SCLC cells to BI-2536. Targeting AURKA with alisertib, at a non-toxic concentration, reduced the BI-2536-induced accumulation of BRCA1 and RAD51, leading to DNA repair defects and mitotic cell death in SCLC cells. In vivo experiments confirmed that combining BI-2536 with alisertib impaired DNA repair capacity and significantly delayed tumor growth. Additionally, GSEA analysis and loss- and gain-of-function assays demonstrated that MYC/MYCN signaling is crucial for determining the sensitivity of SCLC cells to BI-2536 and its combination with alisertib. The study further revealed a positive correlation between RAD51 expression and PLK1/AURKA expression, and a negative correlation with the IC 50 values of BI-2536. Manipulating RAD51 expression significantly influenced the efficacy of BI-2536 and restored the MYC/MYCN-induced enhancement of BI-2536 sensitivity in SCLC cells. Our findings indicate that the BRCA1 and MYC/MYCN-RAD51 axes govern the response of small cell lung cancer to BI-2536 and its combination with alisertib. This study propose the combined use of BI-2536 and alisertib as a novel therapeutic strategy for the treatment of SCLC patients with MYC/MYCN activation., (© 2024. The Author(s).)

Introduction: Small Cell Lung Cancer (SCLC) can be classified into transcriptional subtypes with distinct degrees of neuroendocrine (NE) differentiation. Recent evidence supports plasticity among subtypes with a bias toward adoption of low-NE states during disease progression or upon acquired chemotherapy resistance. Here, we identify a role for SMARCA4, the catalytic subunit of the SWI/SNF complex, as a regulator of subtype shift in SCLC., Methods: ATACseq and RNAseq experiments were performed in SCLC cells after pharmacological inhibition of SMARCA4. DNA binding of SMARCA4 was characterized by ChIPseq in high-NE SCLC patient derived xenografts (PDXs). Enrichment analyses were applied to transcriptomic data. Combination of FHD-286 and afatinib was tested in vitro and in a set of chemo-resistant SCLC PDXs in vivo., Results: SMARCA4 expression positively correlates with that of NE genes in both SCLC cell lines and patient tumors. Pharmacological inhibition of SMARCA4 with FHD-286 induces the loss of NE features and downregulates neuroendocrine and neuronal signaling pathways while activating non-NE factors. SMARCA4 binds to gene loci encoding NE-lineage transcription factors ASCL1 and NEUROD1 and alters chromatin accessibility, enhancing NE programs. Enrichment analysis applied to high-confidence SMARCA4 targets confirmed neuron related pathways as the top GO Biological processes regulated by SMARCA4 in SCLC. In parallel, SMARCA4 also controls REST, a known suppressor of the NE phenotype, by regulating SRRM4-dependent REST transcript splicing. Furthermore, SMARCA4 inhibition drives ERBB pathway activation in SCLC, rendering SCLC tumors sensitive to afatinib., Conclusions: This study nominates SMARCA4 as a key regulator of the NE state plasticity and defines a novel therapeutic strategy for SCLC., (© 2024. The Author(s).)

Small cell lung cancer (SCLC) is a highly malignant and heterogeneous cancer with limited therapeutic options and prognosis prediction models. Here, we analyzed formalin-fixed, paraffin-embedded (FFPE) samples of surgical resections by proteomic profiling, and stratified SCLC into three proteomic subtypes (S-I, S-II, and S-III) with distinct clinical outcomes and chemotherapy responses. The proteomic subtyping was an independent prognostic factor and performed better than current tumor-node-metastasis or Veterans Administration Lung Study Group staging methods. The subtyping results could be further validated using FFPE biopsy samples from an independent cohort, extending the analysis to both surgical and biopsy samples. The signatures of the S-II subtype in particular suggested potential benefits from immunotherapy. Differentially overexpressed proteins in S-III, the worst prognostic subtype, allowed us to nominate potential therapeutic targets, indicating that patient selection may bring new hope for previously failed clinical trials. Finally, analysis of an independent cohort of SCLC patients who had received immunotherapy validated the prediction that the S-II patients had better progression-free survival and overall survival after first-line immunotherapy. Collectively, our study provides the rationale for future clinical investigations to validate the current findings for more accurate prognosis prediction and precise treatments., (© The Author(s) 2024. Published by Oxford University Press and Science Press on behalf of the Beijing Institute of Genomics, Chinese Academy of Sciences / China National Center for Bioinformation and Genetics Society of China.)

Small cell lung cancer (SCLC) is an aggressive and lethal malignancy. Achaete-scute homolog 1 (ASCL1) is essential for the initiation of SCLC in mice and the development of pulmonary neuroendocrine cells (PNEC), which are the major cells of origin for SCLC. However, the regulatory mechanism of ASCL1 in SCLC remains elusive. Here, we found that ASCL1 expression gradually increases as the tumors grow in a mouse SCLC model, and is regulated by the cell cycle. Mechanistically, CDK2-CyclinA2 complex phosphorylates ASCL1, which results in increased proteasome-mediated ASCL1 protein degradation by E3 ubiquitin ligase HUWE1 during mitosis. TCF3 promotes the multisite phosphorylation of ASCL1 through the CDK2-CyclinA2 complex and the interaction between ASCL1 and TCF3 protects ASCL1 from degradation. The dissociation of TCF3 from ASCL1 during mitosis accelerates the degradation of ASCL1. In addition, chemotherapy drugs greatly reduce the transcription of ASCL1 in SCLC cells. Depletion of ASCL1 sensitizes SCLC cells to chemotherapy drugs. Together, our study demonstrates that ASCL1 is a cell-cycle-regulated protein and provides a theoretical basis for applying cell-cycle-related antitumor drugs in SCLC treatment. Implications:Our study revealed a novel regulatory mechanism of ASCL1 by cell cycle and chemotherapy drugs in SCLC. Treating patients with SCLC with a combination of ASCL1-targeting therapy and chemotherapy drugs could potentially be beneficial., (©2024 The Authors; Published by the American Association for Cancer Research.)

Small cell lung cancer (SCLC) is characterized by a dismal prognosis. Many efforts have been made so far for identifying novel biomarkers for a personalized treatment for SCLC patients. Schlafen 11 (SLFN11) is a protein differently expressed in many cancers and recently emerged as a new potential biomarker. Lower expression of SLFN11 correlates with a worse prognosis in SCLC and other tumors. SLFN11 has a role in tumorigenesis, inducing replication arrest in the presence of DNA damage through the block of the replication fork. SLFN11 interacts also with chromatin accessibility, proteotoxic stress and mammalian target of rapamycin signalling pathway. The expression of SLFN11 is regulated by epigenetic mechanisms, including promoter methylation, histone deacetylation, and the histone methylation. The downregulation of SLFN11 correlates with a worse response to topoisomerase I and II inhibitors, alkylating agents, and poly ADP-ribose polymerase inhibitors in different cancer types. Some studies exploring strategies for overcoming drug resistance in tumors with low levels of SLFN11 showed promising results. One of these strategies includes the interaction with the Ataxia Telangiectasia and Rad3-related pathway, constitutively activated and leading to cell survival and tumor growth in the presence of low levels of SLFN11. Furthermore, the expression of SLFN11 is dynamic through time and different anticancer therapy and liquid biopsy seems to be an attractive tool for catching SLFN11 different expressions. Despite this, further investigations exploring SLFN11 as a predictive biomarker, its longitudinal changes, and new strategies to overcome drug resistances are needed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Systemic inflammation is believed to contribute to small cell lung cancer (SCLC) progression, but the underlying relationship remains unclear. Lipocalin-2, a potential biomarker of inflammation, has been implicated in various cancers but its prognostic value in SCLC is underexplored., Methods: We retrospectively analyzed 191 patients with SCLC (72 with limited-stage [LD] and 119 with extensive-stage) treated using platinum-based chemotherapy. Lipocalin-2 expression was evaluated using immunohistochemistry. Optimal cutoff values for lipocalin-2 and neutrophil-to-lymphocyte ratio (NLR) were determined using time-dependent receiver operating characteristic curve analysis. The pectoralis muscle index was used to assess sarcopenia., Results: In LD-SCLC, high lipocalin-2 expression was associated with worse progression-free survival (PFS; median: 7.0 vs. 15.9 months, p = 0.015) and overall survival (OS; median: 12.9 vs. 30.3 months, p = 0.035) compared with low lipocalin-2 expression. Patients were stratified into three prognostic groups by combining lipocalin-2 with NLR: low lipocalin-2/low NLR, high lipocalin-2/low NLR or low lipocalin-2/high NLR, and high lipocalin-2/high NLR (median PFS: 17.3 vs. 11.0 vs. 6.3 months, p = 0.004; median OS: 30.5 vs. 17.3 vs. 8.6 months, p = 0.002). Similar trends were observed when combining lipocalin-2 with the pectoralis muscle index. High lipocalin-2 expression was also associated with lower complete response rates (18.9% vs. 34.3%, p = 0.035). No significant prognostic implications were found for lipocalin-2 in extensive-stage SCLC., Conclusions: High lipocalin-2 expression is potentially associated with poorer survival in LD-SCLC. Combining lipocalin-2 with other inflammation-related markers could improve prognostic stratification., (© 2024 The Author(s). Thoracic Cancer published by John Wiley & Sons Australia, Ltd.)

Few efficacious treatment options are available for patients with small cell lung carcinoma (SCLC), indicating the need to develop novel therapeutic approaches. In this study, we explored kinesin family member 11 (KIF11), a potential therapeutic target in SCLC. An analysis of publicly available data suggested that KIF11 mRNA expression levels are significantly higher in SCLC tissues than in normal lung tissues. When KIF11 was targeted by RNA interference or a small-molecule inhibitor (SB743921) in two SCLC cell lines, Lu-135 and NCI-H69, cell cycle progression was arrested at the G2/M phase with complete growth suppression. Further work suggested that the two cell lines were more significantly affected when both KIF11 and BCL2L1, an anti-apoptotic BCL2 family member, were inhibited. This dual inhibition resulted in markedly decreased cell viability. These findings collectively indicate that SCLC cells are critically dependent on KIF11 activity for survival and/or proliferation, as well as that KIF11 inhibition could be a new strategy for SCLC treatment.

Small cell lung cancer (SCLC) is a recalcitrant cancer characterized by high frequency loss-of-function mutations in tumor suppressors with a lack of targeted therapy due to absence of high frequency gain-of-function abnormalities in oncogenes. SMARCAL1 is a member of the ATP-dependent chromatin remodeling protein SNF2 family that plays critical roles in DNA damage repair and genome stability maintenance. Here, we showed that SMARCAL1 was overexpressed in SCLC patient samples and was inversely associated with overall survival of the patients. SMARCAL1 was required for SCLC cell proliferation and genome integrity. Mass spectrometry revealed that PAR6B was a downstream SMARCAL1 signal molecule which rescued inhibitory effects caused by silencing of SMARCAL1. By screening of 36 FDA-approved clinically available agents related to DNA damage repair, we found that an aza-anthracenedione, pixantrone, was a potent SMARCAL1 inhibitor which suppressed the expression of SMARCAL1 and PAR6B at protein level. Pixantrone caused DNA damage and exhibited inhibitory effects on SCLC cells in vitro and in a patient-derived xenograft mouse model. These results indicated that SMARCAL1 functions as an oncogene in SCLC, and pixantrone as a SMARCAL1 inhibitor bears therapeutic potentials in this deadly disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Small-cell lung cancer (SCLC) is the most fatal form of lung cancer. Intratumoral heterogeneity, marked by neuroendocrine (NE) and non-neuroendocrine (non-NE) cell states, defines SCLC, but the cell-extrinsic drivers of SCLC plasticity are poorly understood. To map the landscape of SCLC tumor microenvironment (TME), we apply spatially resolved transcriptomics and quantitative mass spectrometry-based proteomics to metastatic SCLC tumors obtained via rapid autopsy. The phenotype and overall composition of non-malignant cells in the TME exhibit substantial variability, closely mirroring the tumor phenotype, suggesting TME-driven reprogramming of NE cell states. We identify cancer-associated fibroblasts (CAFs) as a crucial element of SCLC TME heterogeneity, contributing to immune exclusion, and predicting exceptionally poor prognosis. Our work provides a comprehensive map of SCLC tumor and TME ecosystems, emphasizing their pivotal role in SCLC's adaptable nature, opening possibilities for reprogramming the TME-tumor communications that shape SCLC tumor states., Competing Interests: Declaration of interests A.T. received grants to NCI from EMD Serono Research & Development, AstraZeneca, Gilead Sciences, and ProLynx during the conduct of the study., (Published by Elsevier Inc.)

The olfactory epithelium undergoes neuronal regeneration from basal stem cells and is susceptible to olfactory neuroblastoma (ONB), a rare tumor of unclear origins. Employing alterations in Rb1/Trp53/Myc (RPM), we establish a genetically engineered mouse model of high-grade metastatic ONB exhibiting a NEUROD1 + immature neuronal phenotype. We demonstrate that globose basal cells (GBCs) are a permissive cell of origin for ONB and that ONBs exhibit cell fate heterogeneity that mimics normal GBC developmental trajectories. ASCL1 loss in RPM ONB leads to emergence of non-neuronal histopathologies, including a POU2F3 + microvillar-like state. Similar to small-cell lung cancer (SCLC), mouse and human ONBs exhibit mutually exclusive NEUROD1 and POU2F3-like states, an immune-cold tumor microenvironment, intratumoral cell fate heterogeneity comprising neuronal and non-neuronal lineages, and cell fate plasticity-evidenced by barcode-based lineage tracing and single-cell transcriptomics. Collectively, our findings highlight conserved similarities between ONB and neuroendocrine tumors with significant implications for ONB classification and treatment., Competing Interests: Declaration of interests TGO has a patent related to SCLC subtypes and a sponsored research agreement with Auron Therapeutics, serves on the scientific advisory board (SAB) for Lung Cancer Research Foundation, and as a consulting editor for Cancer Research and Genes & Development. BJG has interest in Rhino Therapeutics and is on the SAB for Smell and Taste Association of North America. J.C. has equity in Mirati Therapeutics and provision of services for Sonata Therapeutics. D.J. has consulted for Regeneron and ST Stent., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Small-cell lung cancer (SCLC) is an aggressive cancer for which immune checkpoint inhibitors (ICI) have had only limited success. Bispecific T-cell engagers are promising therapeutic alternatives for ICI-resistant tumors, but not all patients with SCLC are responsive. Herein, to integrate CD137 costimulatory function into a T-cell engager format and thereby augment therapeutic efficacy, we generated a CD3/CD137 dual-specific Fab and engineered a DLL3-targeted trispecific antibody (DLL3 trispecific). The CD3/CD137 dual-specific Fab was generated to competitively bind to CD3 and CD137 to prevent DLL3-independent cross-linking of CD3 and CD137, which could lead to systemic T-cell activation. We demonstrated that DLL3 trispecific induced better tumor growth control and a marked increase in the number of intratumoral T cells compared with a conventional DLL3-targeted bispecific T-cell engager. These findings suggest that DLL3 trispecific can exert potent efficacy by inducing concurrent CD137 costimulation and provide a promising therapeutic option for SCLC., (©2024 American Association for Cancer Research.)

The transformation of lung adenocarcinoma to small cell lung cancer (SCLC) is a recognized resistance mechanism and a hindrance to therapies using epidermal growth factor receptor tyrosine kinase inhibitors (TKIs). The paucity of pretranslational/posttranslational clinical samples limits the deeper understanding of resistance mechanisms and the exploration of effective therapeutic strategies. Here, we developed preclinical neuroendocrine (NE) transformation models. Next, we identified a transcriptional reprogramming mechanism that drives resistance to erlotinib in NE transformation cell lines and cell-derived xenograft mice. We observed the enhanced expression of genes involved in the EHMT2 and WNT/β-catenin pathways. In addition, we demonstrated that EHMT2 increases methylation of the SFRP1 promoter region to reduce SFRP1 expression, followed by activation of the WNT/β-catenin pathway and TKI-mediated NE transformation. Notably, the similar expression alterations of EHMT2 and SFRP1 were observed in transformed SCLC samples obtained from clinical patients. Importantly, suppression of EHMT2 with selective inhibitors restored the sensitivity of NE transformation cell lines to erlotinib and delayed resistance in cell-derived xenograft mice. We identify a transcriptional reprogramming process in NE transformation and provide a potential therapeutic target for overcoming resistance to erlotinib., Competing Interests: Competing interests statement:The authors declare no competing interest.