Search

Colorectal cancer (CRC) stands as the second most common cause of cancer-related mortality globally and p53, a widely recognized tumor suppressor, contributes to the development of CRC. Ubiquitin-specific protease 36 (USP36), belonging to the deubiquitinating enzyme family, is involved in tumor progression across multiple cancers. However, the underlying molecular mechanism in which USP36 regulates p53 signaling pathway in CRC is unclear. Here, our study revealed that USP36 was increased in CRC tissues and associated with unfavorable prognosis. Functionally, elevated USP36 could promote proliferation, migration, and invasion of CRC cells in vitro and in vivo. Mechanistically, USP36 could interact with and stabilize RBM28 via deubiquitination at K162 residue. Further, upregulated RBM28 could bind with p53 to suppress its transcriptional activity and therefore inactivate p53 signaling pathway. Collectively, our investigation identified the novel USP36/RBM28/p53 axis and its involvement in promoting cell proliferation and metastasis in CRC, which presents a promising therapeutic strategy for CRC treatment., Competing Interests: Competing interests The authors declare no competing interests. Ethical approval Approval from the ethics committee of The First School of Clinical Medicine, Nanjing Medical University was obtained for the human tissue study, and informed consent was provided by all patients involved. All animal experiments are conducted with the approval of the Committee on the Ethics of Animal Experiments of Nanjing Medical University. The ethical number of the animal experiment is IACUC-2310047. All methods were performed in accordance with the relevant guidelines and regulations., (© 2024. The Author(s).)

Epigenetic regulation is a pivotal factor during neuroblastoma (NB) pathogenesis and investigations into cancer epigenetics are actively underway to identify novel therapeutic strategies for NB patients. SUV39H1, a member of the H3K9 methyltransferase family, contributing to tumorigenesis across multiple malignancies. However, its specific role in NB remains unexplored. In this study, we conducted a high-throughput screen utilizing a compound library containing 288 epigenetic drugs, leading to the identification of chaetocin as the most potent NB inhibitor by targeting SUV39H1. Genetic manipulation and therapeutic inhibition of SUV39H1 significantly impacted proliferation, migration, cell cycle phases, and apoptosis in NB cells. Concurrently, chaetocin demonstrated robust anti-tumor efficacy in vivo with tolerable toxicity. RNA-seq unveiled that SUV39H1 knockdown and inhibition down-regulated cell cycle pathways, impacting vital genes such as AURKA. Besides, MCPIP1 emerged as a novel tumor suppressor following SUV39H1 inhibition, which decreased AURKA expression in NB. In detail, SUV39H1 mediated the enrichment of H3K9me3 at the promoter region of MCPIP1, repressing the MCPIP1-mediated degradation of AURKA and facilitating the subsequent accumulation of AURKA, which revealed the oncogenic role of SUV39H1 via the SUV39H1-MCPIP1-AURKA signaling axis in NB. Therapeutic inhibition of SUV39H1 using chaetocin emerges as an effective and safe strategy for NB patients. Illustration of the oncogenic pathway regulated by SUV39H1 in NB., (© 2024. The Author(s).)

Dysregulated N 6 -methyladenosine (m 6 A) modification has been associated with breast cancer pathogenesis. Hypoxia which characterizes solid tumors is known to reprogram the m 6 A epitranscriptome, but the underlying mechanisms of how this process contributes to breast cancer progression remain poorly understood. Through integrative analyses of m 6 A-RIP sequencing and RNA sequencing databases, we reveal a cluster of mRNAs with upregulated m 6 A methylation and expression under hypoxia, that are enriched by many oncogenic pathways, including PI3K-Akt signaling. Furthermore, we identify the mRNA, RIPOR3, as a target of METTL3-mediated m 6 A methylation in response to hypoxia. We find that m 6 A methylation stabilizes RIPOR3, increasing its protein expression in a METTL3 catalytic activity-dependent manner, and consequently driving breast tumor growth and metastasis. RIPOR3 is found to be overexpressed in breast cancer cell lines and tumor tissues from breast cancer patients, in whom elevated RIPOR3 is associated with a worse prognosis. Mechanistically, we show that RIPOR3 interacts with EGFR and is essential for the PI3K-Akt pathway activation. In conclusion, we identify RIPOR3 as a hypoxia-stabilized oncogenic driver via METTL3-mediated m 6 A methylation, thus provide a potential therapeutic target for breast cancer., Competing Interests: Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

In the clinical development of farnesyltransferase inhibitors (FTIs) for HRAS-mutant tumors, responses varied by cancer type. Co-occurring mutations may affect responses. We aimed to uncover cooperative genetic events specific to HRAS-mutant tumors and to study their effect on sensitivity to FTIs. Using targeted sequencing data from the MSK-IMPACT and Dana-Farber Cancer Institute Genomic Evidence Neoplasia Information Exchange databases, we identified comutations that were observed predominantly in HRAS-mutant versus KRAS-mutant or NRAS-mutant cancers. HRAS-mutant cancers had a higher frequency of coaltered mutations (48.8%) in the MAPK, PI3K, or RTK pathway genes, compared with KRAS-mutant (41.4%) and NRAS-mutant (38.4%) cancers (p < 0.05). Class 3 BRAF, NF1, PTEN, and PIK3CA mutations were more prevalent in HRAS-mutant lineages. To study the effects of comutations on sensitivity to FTIs, Hras G13R was transfected into "RASless" (Kras lox/lox /Hras -/- /Nras -/- /RERT ert/ert ) mouse embryonic fibroblasts (MEFs), which sensitized nontransfected MEFs to tipifarnib. Comutation in the form of Pten or Nf1 deletion and Pik3ca H1047R transduction led to resistance to tipifarnib in Hras G13R -transfected MEFs in the presence or absence of Kras WT , whereas Braf G466E transduction led to resistance to tipifarnib only in the presence of Kras WT . Combined treatment with tipifarnib and MEK inhibition sensitized cells to tipifarnib in all settings, including in MEFs with PI3K pathway comutations. HRAS-mutant tumors demonstrate lineage-dependent MAPK or PI3K pathway alterations, which confer resistance to tipifarnib. The combined use of FTIs and MEK inhibition is a promising strategy for HRAS-mutant tumors., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

The etiology of idiopathic multicentric Castleman disease (iMCD) is poorly understood, and the identification of targetable disease mediators remains an unmet clinical need. Thus, we firstly employed single-cell RNA sequencing (scRNA-seq) to elucidate the landscape of the immune repertoire of peripheral blood mononuclear cells (PBMNCs) in iMCD and to identify additional driver cytokines/cells/pathways to address IL-6 blockade-refractory cases. We revealed that the inflammatory cytokine storm observed in iMCD was a significant phenomenon pervasive across all immune cells. B-plasma cell subsets was the main source of IL-6. The IL-6 signaling pathway was significantly activated across a spectrum of immune cells. Systemic upregulation of CXCL13 is mainly driven by peripheral helper T (Tph) and regulatory T (Treg) cells. Notably, a significant positive interaction was observed between CXCL13-expressing T cells and IL-6 signaling-activated B cells. This study provides an immune perspective on PBMNCs in iMCD at the single-cell level, unveiling pathways or targets characterized by atypical inflammatory expression that could potentially serve as promising candidates for therapeutic intervention in iMCD., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Chemoresistance is an important cause of treatment failure in bladder cancer, and identifying genes that confer drug resistance is an important step toward developing new therapeutic strategies to improve treatment outcomes. In the present study, we show that gemcitabine plus cisplatin (GEM/DDP) therapy induces NF-κB signaling, which promotes p65-mediated transcriptional activation of OIP5. OIP5 recruits the E3 ubiquitin ligase TRIP12 to bind to and degrade the phosphatase PPP1CB, thereby enhancing the transcription factor activity of YBX1. This in turn upregulates drug-resistance-related genes under the transcriptional control of YBX1, leading to chemoresistance. Moreover, PPP1CB degradation can enhance the phosphorylation activity of IKKβ, triggering the NF-κB signaling cascade, which further stimulates OIP5 gene expression, thus forming a negative feedback regulatory loop. Consistently, elevated OIP5 expression was associated with chemoresistance and poor prognosis in patients with bladder cancer. Furthermore, we used a CRISPR/Cas9-based engineered gene circuit, which can monitor the progression of chemoresistance in real-time, to induce OIP5 knockout upon detection of increased NF-κB signaling. The gene circuit significantly inhibited tumor cell growth in vivo, underscoring the potential for synergy between gene therapy and chemotherapy in the treatment of cancer., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

The DNA replication stress (DRS) response is a crucial homeostatic mechanism for maintaining genome integrity in the face of intrinsic and extrinsic barriers to DNA replication. Importantly, DRS is often significantly increased in tumor cells, making tumors dependent on the cellular DRS response for growth and survival. Rad9-Hus1-Rad1 Interacting Nuclear Orphan 1 (RHNO1), a protein involved in the DRS response, has recently emerged as a potential therapeutic target in cancer. RHNO1 interacts with the 9-1-1 checkpoint clamp and TopBP1 to activate the ATR/Chk1 signaling pathway, the crucial mediator of the DRS response. Moreover, RHNO1 was also recently identified as a key facilitator of theta-mediated end joining (TMEJ), a DNA repair mechanism implicated in cancer progression and chemoresistance. In this literature review, we provide an overview of our current understanding of RHNO1, including its structure, function in the DRS response, and role in DNA repair, and discuss its potential as a cancer therapeutic target. Therapeutic targeting of RHNO1 holds promise for tumors with elevated DRS as well as tumors with DNA repair deficiencies, including homologous recombination DNA repair deficient (HRD) tumors. Further investigation into RHNO1 function in cancer, and development of approaches to target RHNO1, are expected to yield novel strategies for cancer treatment., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

The proneural-mesenchymal (PN-MES) transformation of glioma stem cells (GSCs) can significantly increase proliferation, invasion, chemotherapy tolerance, and recurrence. M2-like polarization of tumor-associated macrophages (TAMs) has a strong immunosuppressive effect, promoting tumor malignancy and angiogenesis. There is limited understanding on the interactions between GSCs and TAMs as well as their associated molecular mechanisms. In the present study, bioinformatics analysis, GSC and TAM co-culture, determination of TAM polarization phenotypes, and other in vitro experiments confirmed that CCL2 secreted by MES-GSCs promotes TAM-M2 polarization via the IKZF1-CD84-SHP2 pathway and PN-MES transformation of GSCs via the IKZF1-LRG1 pathway in TAMs. IKZF1 inhibitors could significantly reduce tumor volumes in animal glioma models and improve survival, as well as suppress TAM-M2 polarization and the GSC malignant phenotype. The results of this study indicate the important interaction between TAMs and GSCs in the glioma microenvironment as well as its role in tumor progression. The findings also suggest a novel target for follow-up clinical transformation research on the regulation of TAM function and GSCs malignant phenotype., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Cancer-associated fibroblasts (CAFs) are known to promote angiogenesis in oral squamous cell carcinoma (OSCC). However, the epigenetic mechanisms through which CAFs facilitate angiogenesis within the tumor microenvironment are still poorly characterized. Nicotinamide N'-methyltransferase (NNMT), a member of the N-methyltransferase family, was found to be a key molecule in the activation of CAFs. This study shows that NNMT in fibroblasts contributes to angiogenesis and tumor growth through an epigenetic reprogramming-ETS2-VEGFA signaling axis in OSCC. Single-cell RNA Sequencing (scRNA-seq) analysis suggests that NNMT is mainly highly expressed in fibroblasts of head and neck squamous cell carcinoma (HNSCC). Moreover, analysis of the TCGA database and multiple immunohistochemical staining of clinical samples also identified a positive correlation between NNMT and tumor angiogenesis. This research further employed an assembled organoid model and a fibroblast-endothelial cell co-culture model to authenticate the proangiogenic ability of NNMT. At the molecular level, high expression of NNMT in CAFs was found to promote ETS2 expression by regulating H3K27 methylation level through mediating methylation deposition. Furthermore, ETS2 was verified to be an activating transcription factor of VEGFA in this study. Collectively, our findings delineate an epigenetic molecular regulatory network of angiogenesis and provide a theoretical basis for exploring new targets and clinical strategy in OSCC., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Circular RNAs (circRNAs) have emerged as key regulators of cancer occurrence and progression, as well as promising biomarkers for cancer diagnosis and prognosis. However, the potential mechanisms of circRNAs implicated in lymph node (LN) metastasis of gastric cancer remain unclear. Herein, we identify a novel N6-methyladenosine (m6A) modified circRNA, circPAK2, which is significantly upregulated in gastric cancer tissues and metastatic LN tissues. Functionally, circPAK2 enhances the migration, invasion, lymphangiogenesis, angiogenesis, epithelial-mesenchymal transition (EMT), and metastasis of gastric cancer in vitro and in vivo. Mechanistically, circPAK2 is exported by YTH domain-containing protein 1 (YTHDC1) from the nucleus to the cytoplasm in an m6A methylation-dependent manner. Moreover, increased cytoplasmic circPAK2 interacts with Insulin-Like Growth Factor 2 mRNA-Binding Proteins (IGF2BPs) and forms a circPAK2/IGF2BPs/VEGFA complex to stabilize VEGFA mRNA, which contributes to gastric cancer vasculature formation and aggressiveness. Clinically, high circPAK2 expression is positively associated with LN metastasis and poor prognosis in gastric cancer. This study highlights m6A-modified circPAK2 as a key regulator of LN metastasis of gastric cancer, thus supporting circPAK2 as a promising therapeutic target and prognostic biomarker for gastric cancer., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Genetic changes in the ERBB family of receptor tyrosine kinases serve as oncogenic driver events and predictive biomarkers for ERBB inhibitor drugs. ERBB3 is a pseudokinase member of the family that, although lacking a fully active kinase domain, is well known for its potent signaling activity as a heterodimeric complex with ERBB2. Previous studies have identified few transforming ERBB3 mutations while the great majority of the hundreds of different somatic ERBB3 variants observed in different cancer types remain of unknown significance. Here, we describe an unbiased functional genetics screen of the transforming potential of thousands of ERBB3 mutations in parallel. The screen based on a previously described iSCREAM (in vitro screen of activating mutations) platform, and addressing ERBB3 pseudokinase signaling in a context of ERBB3/ERBB2 heterodimers, identified 18 hit mutations. Validation experiments in Ba/F3, NIH 3T3, and MCF10A cell backgrounds demonstrated the presence of both previously known and unknown transforming ERBB3 missense mutations functioning either as single variants or in cis as a pairwise combination. Drug sensitivity assays with trastuzumab, pertuzumab and neratinib indicated actionability of the transforming ERBB3 variants., (© 2024. The Author(s).)

The MUC1 gene evolved in mammals for adaptation of barrier tissues in response to infections and damage. Paraspeckles are nuclear bodies formed on the NEAT1 lncRNA in response to loss of homeostasis. There is no known intersection of MUC1 with NEAT1 or paraspeckles. Here, we demonstrate that the MUC1-C subunit plays an essential role in regulating NEAT1 expression. MUC1-C activates the NEAT1 gene with induction of the NEAT1&#95;1 and NEAT1&#95;2 isoforms by NF-κB- and MYC-mediated mechanisms. MUC1-C/MYC signaling also induces expression of the SFPQ, NONO and FUS RNA binding proteins (RBPs) that associate with NEAT1&#95;2 and are necessary for paraspeckle formation. MUC1-C integrates activation of NEAT1 and RBP-encoding genes by recruiting the PBAF chromatin remodeling complex and increasing chromatin accessibility of their respective regulatory regions. We further demonstrate that MUC1-C and NEAT1 form an auto-inductive pathway that drives common sets of genes conferring responses to inflammation and loss of homeostasis. Of functional significance, we find that the MUC1-C/NEAT1 pathway is of importance for the cancer stem cell (CSC) state and anti-cancer drug resistance. These findings identify a previously unrecognized role for MUC1-C in the regulation of NEAT1, RBPs, and paraspeckles that has been co-opted in promoting cancer progression., (© 2024. The Author(s).)

It has been demonstrated that tRNA-derived small RNAs (tsRNAs) perform essential functions in the pathophysiology of cancer. In this study, we focused on the possible mechanisms of tRF-33-P4R8YP9LON4VDP (tRF-33) underlying the development of gastric malignancy. In total, 454 tissue samples with different gastric mucosal lesions were collected. The tRF-33 expression level in different cohorts was determined, and its value for diagnostic efficiency and prognosis evaluation were assessed. Cell proliferation assays, Transwell assay, flow cytometry, and xenotransplantation model were used to evaluate its effect on gastric cancer cells. The molecular mechanism was verified by fluorescence in situ hybridization, dual luciferase assay, Western blot, and RNA binding protein immunoprecipitation. The results showed that the expression of tRF-33 exhibited a gradual modification from normal control samples to gastritis tissues, early and latent stage of gastric cancer tissues. Consequently, tRF-33 holds significant potential as a predictive and diagnostic biomarker for gastric malignancy. Over-expression of tRF-33 inhibited gastric cancer cell progression and metastatic viability, and induced cell apoptosis. Tumorigenicity in nude mice showed the suppressive characteristics of tRF-33. Mechanistic investigation revealed that tRF-33 exerted silencing on STAT3 mRNA via binding to AGO2. In conclusion, tRF-33 exhibited values in diagnosing gastric cancer and evaluating its prognosis, and suppressed tumor cell viability by inhibiting STAT3 signaling pathway. The schematic mechanisms underlying tRF-33 regulating gastric cancer occurrence. tRF-33 binds to AGO2 proteins and then negatively regulates STAT3 expression through targeting its 3'UTR. The downregulated expression of STAT3 results in the decrease of STAT3 and p-STAT3 and further blocks the transcription of the downstream genes and finally inhibits the gastric cancer occurrence. MMP-9, matrix metalloproteinase-9; Bcl-2, B-cell lymphoma-2; STAT3, signal transducer and activator of transcription 3; UTR, untranslated region., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

We have performed a functional in vivo mutagenesis screen to identify genes that, when altered, cooperate with a heterozygous Pten mutation to promote prostate tumour formation. Two genes, Bzw2 and Eif5a2, which have been implicated in the process of protein translation, were selected for further validation. Using prostate organoid models, we show that either Bzw2 downregulation or EIF5A2 overexpression leads to increased organoid size and in vivo prostate growth. We show that both genes impact the PI3K pathway and drive a sustained increase in phospho-AKT expression, with PTEN protein levels reduced in both models. Mechanistic studies reveal that EIF5A2 is directly implicated in PTEN protein translation. Analysis of patient datasets identified EIF5A2 amplifications in many types of human cancer, including the prostate. Human prostate cancer samples in two independent cohorts showed a correlation between increased levels of EIF5A2 and upregulation of a PI3K pathway gene signature. Consistent with this, organoids with high levels of EIF5A2 were sensitive to AKT inhibitors. Our study identified novel genes that promote prostate cancer formation through upregulation of the PI3K pathway, predicting a strategy to treat patients with genetic aberrations in these genes particularly relevant for EIF5A2 amplified tumours., (© 2024. The Author(s).)

The long-term maintenance of leukaemia stem cells (LSCs) is responsible for the high degree of malignancy in MLL (mixed-lineage leukaemia) rearranged acute myeloid leukaemia (AML). The DNA damage response (DDR) and DOT1L/H3K79me pathways are required to maintain LSCs in MLLr-AML, but little is known about their interplay. This study revealed that the DDR enzyme ATM regulates the maintenance of LSCs in MLLr-AML with a sequential protein-posttranslational-modification manner via CBP-DOT1L. We identified the phosphorylation of CBP by ATM, which confers the stability of CBP by preventing its proteasomal degradation, and characterised the acetylation of DOT1L by CBP, which mediates the high level of H3K79me2 for the expression of leukaemia genes in MLLr-AML. In addition, we revealed that the regulation of CBP-DOT1L axis in MLLr-AML by ATM was independent of DNA damage activation. Our findings provide insight into the signalling pathways involoved in MLLr-AML and broaden the understanding of the role of DDR enzymes beyond processing DNA damage, as well as identigying them as potent cancer targets., (© 2024. The Author(s).)

MET amplification/mutations are important targetable oncogenic drivers in NSCLC, however, acquired resistance is inevitable and the majority of patients with targetable MET alterations fail to respond to MET tyrosine kinase inhibitors (TKIs). Furthermore, MET amplification is among the most common mediators of TKI resistance. As such, novel therapies to target MET pathway and overcome MET TKI resistance are clearly needed. Here we show that the epithelial-mesenchymal transition (EMT) transcription factor, TWIST1 is a key downstream mediator of HGF/MET induced resistance through suppression of p27 and targeting TWIST1 can overcome resistance. We found that TWIST1 is overexpressed at the time of TKI resistance in multiple MET-dependent TKI acquired resistance PDX models. We have shown for the first time that MET directly stabilized the TWIST protein leading to TKI resistance and that TWIST1 was required for MET-driven lung tumorigenesis as well as could induce MET TKI resistance when overexpressed. TWIST1 mediated MET TKI resistance through suppression of p27 expression and genetic or pharmacologic inhibition of TWIST1 overcame TKI resistance in vitro and in vivo. Our findings suggest that targeting TWIST1 may be an effective therapeutic strategy to overcome resistance in MET-driven NSCLC as well as in other oncogene driven subtypes in which MET amplification is the resistance mechanism., (© 2024. The Author(s).)

The role of the focal adhesion protein kindlin-3 as a tumor suppressor and its interaction mechanisms with extracellular matrix constitute a major field of investigation to better decipher tumor progression. Besides the well-described role of kindlin-3 in integrin activation, evidence regarding modulatory functions between melanoma cells and tumor microenvironment are lacking and data are needed to understand mechanisms driven by kindlin-3 inactivation. Here, we show that kindlin-3 inactivation through knockdown or somatic mutations increases BRAF V600mut melanoma cells oncogenic properties via collagen-related signaling by decreasing cell adhesion and enhancing proliferation and migration in vitro, and by promoting tumor growth in mice. Mechanistic analysis reveals that kindlin-3 interacts with the collagen-activated tyrosine kinase receptor DDR1 (Discoidin domain receptor 1) modulating its expression and its interaction with β1-integrin. Kindlin-3 knockdown or mutational inactivation disrupt DDR1/β1-integrin complex in vitro and in vivo and its loss improves the anti-proliferative effect of DDR1 inhibition. In agreement, kindlin-3 downregulation is associated with DDR1 over-expression in situ and linked to worse melanoma prognosis. Our study reveals a unique mechanism of action of kindlin-3 in the regulation of tumorigenesis mediated by the collagen-activated tyrosine kinase receptor DDR1 thus paving the way for innovative therapeutic targeting approaches in melanoma., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

RNA-binding proteins (RBPs) are critical regulators for RNA transcription and translation. As a key member of RBPs, ELAV-like family protein 2 (CELF2) has been shown to regulate RNA splicing and embryonic hematopoietic development and was frequently seen dysregulated in acute myeloid leukemia (AML). However, the functional role(s) of CELF2 in hematopoiesis and leukemogenesis has not been fully elucidated. In the current study, we showed that Celf2 deficiency in hematopoietic system led to enhanced HSCs self-renewal and differentiation toward myeloid cells in mice. Loss of Celf2 accelerated myeloid cell transformation and AML development in MLL-AF9-induced AML murine models. Gene expression profiling integrated with RNA immunoprecipitation sequencing (RIP-Seq), together with biochemical experiments revealed that CELF2 deficiency stabilizes FAT10 mRNA, promotes FAT10 translation, thereby increases AKT phosphorylation and mTORC1 signaling pathway activation. Notably, combination therapy with a mTORC1 inhibitor (Rapamycin) and a MA9/DOTL1 inhibitor (EPZ-5676) reduced the leukemia burden in MLL-AF9 mice lacking Celf2 in vivo. Our study elucidated a novel mechanism by which the CELF2/FAT10-AKT/mTORC1 axis regulates the proliferation of normal blood cells and the development of AML, thus providing potential therapeutic targets for myeloid leukemia suppression., (© 2024. The Author(s).)

Metastasis causes most cancer-related deaths, and the role and mechanism of periostin (POSTN) in the metastasis of hepatocellular carcinoma (HCC) remain undiscovered. In this study, DEN and HTVi HCC models were performed in hepatic-specific Postn ablation and Postn knock-in mouse to reveal the role of POSTN in HCC metastasis. Furthermore, POSTN was positively correlated with circulating EPCs level and promoted EPC mobilization and tumour infiltration. POSTN also mediated the crosstalk between HCC and EPCs, which promoted metastasis ability and upregulated CD36 expression in HCC through indirect crosstalk. Chemokine arrays further revealed that hepatic-derived POSTN induced elevated CCL2 expression and secretion in EPCs, and CCL2 promoted prometastatic traits in HCC. Mechanistic studies showed that POSTN upregulated CCL2 expression in EPCs via the αvβ3/ILK/NF-κB pathway. CCL2 further induced CD36 expression via the CCR2/STAT3 pathway by directly binding to the promoter region of CD36. Finally, CD36 was verified to have a prometastatic role in vitro and to be correlated with POSTN expression, metastasis and recurrence in HCC in clinical samples. Our findings revealed that crosstalk between HCC and EPCs is mediated by periostin/CCL2/CD36 signalling which promotes HCC metastasis and emphasizes a potential therapeutic strategy for preventing HCC metastasis., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

USP11 is a member of the ubiquitin-specific protease family and plays a crucial role in tumor progression in various cancers. However, the precise mechanism by which USP11 promotes EMT and metastasis in hepatocellular carcinoma (HCC) is not fully understood. In this study, we demonstrated that the USP11 expression was dramatically upregulated in HCC tissues and cell lines. Increased USP11 expression was closely associated with tumor number, vascular invasion, and poor prognosis. Functional experiments demonstrated that USP11 markedly promoted metastasis and EMT in HCC via induction of the transcription factor Snail. Mechanistically, USP11 interacted with and deubiquitinated eEF1A1 on Lys439, thereby inhibiting its ubiquitin-mediated degradation. Subsequently, the elevated expression of eEF1A1 resulted in its binding to SP1, which in turn drove the binding of SP1 to its target HGF gene promoter to increase its transcription. This led to an enhanced expression of HGF and the activation of the downstream PI3K/AKT signaling pathway. We demonstrated that USP11 promotes EMT and metastasis in HCC via eEF1A1/SP1/HGF dependent-EMT. Our findings suggest that the USP11/ eEF1A1/SP1/HGF axis contributes to metastasis in HCC, and therefore, could be considered as a potential therapeutic target for the treatment of HCC., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Reprogramming of lipid metabolism during hepatocarcinogenesis is not well elucidated. Here, we aimed to explore pivotal RNA-binding motif proteins (RBMs) in lipid metabolism and their therapeutic potential in hepatocellular carcinoma (HCC). Through bioinformatic analysis, we identified RBM45 as a critical gene of interest among differentially expressed RBMs in HCC, with significant prognostic relevance. RBM45 influenced the malignant biological phenotype and lipid metabolism of HCC cells. Mechanically, RBM45 promotes de novo lipogenesis in HCC by directly targeting two key enzymes involved in long-chain fatty acid synthesis, ACSL1 and ACSL4. RBM45 also targets Rictor, which has been demonstrated to modulate lipid metabolism profoundly. RBM45 also aided lipid degradation through activating a key fatty acid β oxidation enzyme, CPT1A. Thus, RBM45 boosted lipid synthesis and decomposition, indicating an enhanced utility of lipid fuels in HCC. Clinically, body mass index was positively correlated with RBM45 in human HCCs. The combination of a PI3K/AKT/mTOR pathway inhibitor in vitro or Sorafenib in orthotopic liver cancer mouse models with shRBM45 has a more significant therapeutic effect on liver cancer than the drug alone. In summary, our findings highlight the versatile roles of RBM45 in lipid metabolism reprogramming and its therapeutic potential in HCC. Lipids induced RBM45 expression. In turn, RBM45 promoted the utility of lipid in HCCs through accelerating both de novo lipogenesis and fatty acid β oxidation, which required the participation of Rictor, a core component of mTORC2 that has been demonstrated to modulate lipid metabolism potently, as well as ACSL1/ACSL4, two key enzymes of long-chain fatty acid synthesis. When the first-line chemotherapy drug sorafenib is combined with a PI3K/AKT/mTOR pathway inhibitor (MK2206 is an AKT inhibitor, rapamycin is a mTOR inhibitor, and inhibiting RBM45 can significantly inhibit Rictor), cell cycle, proliferation, lipid metabolism reprogramming, and hepatocarcinogenesis can be significantly inhibited, while apoptosis can be significantly enhanced., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Tripartite motif (TRIM)-containing proteins, one of the largest subfamilies of the RING type E3 ubiquitin ligases, control important biological processes such as cell apoptosis, autophagy, signal transduction, innate immunity and tumorigenesis. So far, the mutual regulation between TRIM family members has rarely been reported. Here, we found for the first time that there was a direct mutual regulation between TRIM21 and TRIM8 in lung and renal cancer cells, mechanistically by activating their proteasome pathway via Lys48 (K48)- linked ubiquitination. Subsequent studies verified that negatively correlated expressions existed in clinical non-small cell lung cancer (NSCLC) and renal cell carcinoma (RCC) tissues, which were closely related to tumor progression. Our findings highlighted a possible homeostasis between TRIM21 and TRIM8 that might possibly affect cell stemness and was expected to provide a new idea for cancer therapy., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Metastasis remains the major cause of treatment failure in patients with nasopharyngeal carcinoma (NPC), in which sustained activation of the Notch signaling plays a critical role. N6-Methyladenosine (m6A)-mediated post-transcriptional regulation is involved in fine-tuning the Notch signaling output; however, the post-transcriptional mechanisms underlying NPC metastasis remain poorly understood. In the present study, we report that insulin-like growth factor 2 mRNA-binding proteins 3 (IGF2BP3) serves as a key m6A reader in NPC. IGF2BP3 expression was significantly upregulated in metastatic NPC and correlated with poor prognosis in patients with NPC. IGF2BP3 overexpression promoted, while IGF2BP3 downregulation inhibited tumor metastasis and the stemness phenotype of NPC cells in vitro and in vivo. Mechanistically, IGF2BP3 maintains NOTCH3 mRNA stability via suppression of CCR4-NOT complex-mediated deadenylation in an m6A-dependent manner, which sustains Notch3 signaling activation and increases the transcription of stemness-associated downstream genes, eventually promoting tumor metastasis. Our findings highlight the pro-metastatic function of the IGF2BP3/Notch3 axis and revealed the precise role of IGF2BP3 in post-transcriptional regulation of NOTCH3, suggesting IGF2BP3 as a novel prognostic biomarker and potential therapeutic target in NPC metastasis., (© 2023. The Author(s).)

Gastric cancer (GC) is one of the most leading cause of malignancies. However, the molecular mechanisms underlying stomach carcinogenesis remain incompletely understood. Dysregulated genetic and epigenetic alternations significantly contribute to GC development. Here, we report that ASH1L and its antisense lncRNA ASH1L-AS1, which are transcribed from the most significant GC-risk signal at 1q22, act as novel oncogenes. The high levels of ASH1L or lncRNA ASH1L-AS1 expression in GC specimens are associated with worse prognosis of patients. In line with this, ASH1L and ASH1L-AS1 are functionally important in promoting GC disease progression. LncRNA ASH1L-AS1 up-regulates ASH1L transcription, increases histone methyltransferase ASH1L expression and elevates genome-wide H3K4me3 modification levels in GC cells. Furthermore, ASH1L-AS1 directly interacts with transcription factor NME1 protein to form the ASH1L-AS1-NME1 ribonucleoprotein, which transcriptionally promotes expression of ASH1L, ASH1L-AS1, KRAS and RAF1, and activates the RAS signaling pathway in GC cells. Taken together, our data demonstrated that the ASH1L-AS1-ASH1L regulatory axis controls histone modification reprogram and activation of the RAS signaling in cancers. Thus, ASH1L-AS1 might be a novel targets of GC therapeutics and diagnosis in the clinic., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Lymphatic metastasis is recognized as the leading manner of metastasis in bladder cancer (BLCa), but hematogenous metastasis accounts for a majority of cancer-associated deaths. The past two decades have witnessed tremendous attention in long non-coding RNAs (lncRNAs), which are a new hope for the development of targeted drug therapy for metastatic cancers; however, the underlying mechanism of lncRNAs involved in BLCa hematogenous metastasis remains to be elucidated. Here, we identified BLCa-associated transcript 3 (BLACAT3), a lncRNA, which was aberrantly upregulated in BLCa and corelated with poor prognosis of patients with muscle-invasive bladder cancer. Methodologically, m6A epitranscriptomic microarray, RNA sequencing and mass spectrometry (MS) were used to screen the key molecules of the regulatory axis. Functional assays, animal models and clinical samples were used to explore the roles of BLACAT3 in BLCa in vitro and in vivo. Mechanistically, m6A modification contributes to BLACAT3 upregulation by stabilizing RNA structure. BLACAT3 recruits YBX3 to shuttle into the nucleus, synergistically enhances NCF2 transcription, and promotes BLCa angiogenesis and hematogenous metastasis by activating downstream NF-κB signaling. Our findings will develop prognosis prediction tools for BLCa patients and discover novel therapeutic biological targets for metastatic BLCa., (© 2023. The Author(s).)

Human dedifferentiated liposarcoma (DDLPS) is a rare but lethal cancer with no driver mutations being identified, hampering the development of targeted therapies. We and others recently reported that constitutive activation of Notch signaling through overexpression of the Notch1 intracellular domain (NICD OE ) in murine adipocytes leads to tumors resembling human DDLPS. However, the mechanisms underlying the oncogenic functions of Notch activation in DDLPS remains unclear. Here, we show that Notch signaling is activated in a subset of human DDLPS and correlates with poor prognosis and expression of MDM2, a defining marker of DDLPS. Metabolic analyses reveal that murine NICD OE DDLPS cells exhibit markedly reduced mitochondrial respiration and increased glycolysis, mimicking the Warburg effect. This metabolic switch is associated with diminished expression of peroxisome proliferator-activated receptor gamma coactivator 1α (Ppargc1a, encoding PGC-1α protein), a master regulator of mitochondrial biogenesis. Genetic ablation of the NICD OE cassette rescues the expression of PGC-1α and mitochondrial respiration. Similarly, overexpression of PGC-1α is sufficient to rescue mitochondria biogenesis, inhibit the growth and promote adipogenic differentiation of DDLPS cells. Together, these data demonstrate that Notch activation inhibits PGC-1α to suppress mitochondrial biogenesis and drive a metabolic switch in DDLPS., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Tuft cells are chemosensory epithelial cells that increase in number following infection or injury to robustly activate the innate immune response to alleviate or promote disease. Recent studies of castration resistant prostate cancer and its subtype, neuroendocrine prostate cancer, revealed Pou2f3+ populations in mouse models. The transcription factor Pou2f3 is a master regulator of the tuft cell lineage. We show that tuft cells are upregulated early during prostate cancer development, and their numbers increase with progression. Cancer-associated tuft cells in the mouse prostate express DCLK1, COX1, COX2, while human tuft cells express COX1. Mouse and human tuft cells exhibit strong activation of signaling pathways including EGFR and SRC-family kinases. While DCLK1 is a mouse tuft cell marker, it is not present in human prostate tuft cells. Tuft cells that appear in mouse models of prostate cancer display genotype-specific tuft cell gene expression signatures. Using bioinformatic analysis tools and publicly available datasets, we characterized prostate tuft cells in aggressive disease and highlighted differences between tuft cell populations. Our findings indicate that tuft cells contribute to the prostate cancer microenvironment and may promote development of more advanced disease. Further research is needed to understand contributions of tuft cells to prostate cancer progression., (© 2023. The Author(s).)

Rare but recurrent mutations in the fibroblast growth factor receptor (FGFR) pathways, most commonly in one of the four FGFR receptor tyrosine kinase genes, can potentially be targeted with broad-spectrum multi-kinase or FGFR selective inhibitors. The complete spectrum of these mutations in paediatric cancers is emerging as precision medicine programs perform comprehensive sequencing of individual tumours. Identification of patients most likely to benefit from FGFR inhibition currently rests on identifying activating FGFR mutations, gene fusions, or gene amplification events. However, the expanding use of transcriptome sequencing (RNAseq) has identified that many tumours overexpress FGFRs, in the absence of any genomic aberration. The challenge now presented is to determine when this indicates true FGFR oncogenic activity. Under-appreciated mechanisms of FGFR pathway activation, including alternate FGFR transcript expression and concomitant FGFR and FGF ligand expression, may mark those tumours where FGFR overexpression is indicative of a dependence on FGFR signalling. In this review, we provide a comprehensive and mechanistic overview of FGFR pathway aberrations and their functional consequences in paediatric cancer. We explore how FGFR over expression might be associated with true receptor activation. Further, we discuss the therapeutic implications of these aberrations in the paediatric setting and outline current and emerging therapeutic strategies to treat paediatric patients with FGFR-driven cancers., (© 2023. The Author(s).)

Inter-patient and intra-tumoral heterogeneity complicate the identification of predictive biomarkers and effective treatments for basal triple negative breast cancer (b-TNBC). Invasion is the initiating event in metastasis and can occur by both collective and single-cell mechanisms. We cultured primary organoids from a b-TNBC genetically engineered mouse model in 3D collagen gels to characterize their invasive behavior. We observed that organoids from the same tumor presented different phenotypes that we classified as non-invasive, collective and disseminative. To identify molecular regulators driving these invasive phenotypes, we developed a workflow to isolate individual organoids from the collagen gels based on invasive morphology and perform RNA sequencing. We next tested the requirement of differentially regulated genes for invasion using shRNA knock-down. Strikingly, KRAS was required for both collective and disseminative phenotypes. We then performed a drug screen targeting signaling nodes upstream and downstream of KRAS. We found that inhibition of EGFR, MAPK/ERK, or PI3K/AKT signaling reduced invasion. Of these, ERK inhibition was striking for its ability to potently inhibit collective invasion and dissemination. We conclude that different cancer cells in the same b-TNBC tumor can express different metastatic molecular programs and identified KRAS and ERK as essential regulators of collective and single cell dissemination., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

The R-RAS2 GTP hydrolase (GTPase) (also known as TC21) has been traditionally considered quite similar to classical RAS proteins at the regulatory and signaling levels. Recently, a long-tail hotspot mutation targeting the R-RAS2/TC21 Gln 72 residue (Q72L) was identified as a potent oncogenic driver. Additional point mutations were also found in other tumors at low frequencies. Despite this, little information is available regarding the transforming role of these mutant versions and their relevance for the tumorigenic properties of already-transformed cancer cells. Here, we report that many of the RRAS2 mutations found in human cancers are highly transforming when expressed in immortalized cell lines. Moreover, the expression of endogenous R-RAS2 Q72L is important for maintaining optimal levels of PI3K and ERK activities as well as for the adhesion, invasiveness, proliferation, and mitochondrial respiration of ovarian and breast cancer cell lines. Endogenous R-RAS2 Q72L also regulates gene expression programs linked to both cell adhesion and inflammatory/immune-related responses. Endogenous R-RAS2 Q72L is also quite relevant for the in vivo tumorigenic activity of these cells. This dependency is observed even though these cancer cell lines bear concurrent gain-of-function mutations in genes encoding RAS signaling elements. Finally, we show that endogenous R-RAS2, unlike the case of classical RAS proteins, specifically localizes in focal adhesions. Collectively, these results indicate that gain-of-function mutations of R-RAS2/TC21 play roles in tumor initiation and maintenance that are not fully redundant with those regulated by classical RAS oncoproteins., (© 2022. The Author(s).)

Osteosarcoma, the most common pediatric bone tumor, is an aggressive heterogeneous malignancy defined by complex chromosomal aberrations. Overall survival rates remain at ~70%, but patients with chemoresistant or metastatic disease have extremely poor outcomes of <30%. A subgroup of tumors harbor amplification of chromosome 8q24.2 and increased expression of the oncogenic long noncoding RNA (lncRNA) Plasmacytoma Variant Translocation-1 (PVT-1), which is associated with an extremely poor clinical prognosis. This study demonstrates that PVT-1 is critical for osteosarcoma tumor-initiation potential. Chromatin Hybridization by RNA Purification analysis identified Tripartite-Motif Containing Family 28 (TRIM28) as a novel PVT-1 binding partner. Mechanistically, co-immunoprecipitation studies showed the PVT-1/TRIM28 complex binds and increases SUMOylation of phosphatidylinositol 3-kinase catalytic subunit type 3 (Vps34), which leads to enhanced ubiquitination and degradation of tumor suppressor complex 2 (TSC2), thus contributing to increased self-renewal and stem cell phenotypes. Furthermore, we identified that osteosarcoma cells with increased PVT-1 have enhanced sensitivity to the SUMOylation inhibitor, TAK-981. Altogether, this study elucidated a role for PVT-1 in the enhancement of cancer stem-like behaviors, including migration and invasion, in osteosarcoma, and identified the novel PVT-1/TRIM28 axis signaling cascade as a potential therapeutic target for osteosarcoma treatment., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Gastric cancer is one of the most lethal human malignancies in the world. Although great efforts are put in developing novel therapeutic targets, the effective targeting drugs are still limited. Recent studies reveal the abnormality of Hippo/YAP axis play critical role in the oncogenic process of gastric cancer. It is of great importance to demonstrate the regulation of Hippo signaling activity and YAP protein turnover in gastric cancer. Besides, the phosphorylation cascade on YAP function, which has been thoroughly investigated, the ubiquitination of YAP is also important in Hippo signaling status. Here, We utilized the DUB (Deubiquitinase) siRNA library to identify critical DUB for Hippo signaling. We discovered OTUB1 as a critical factor to facilitate gastric cancer cell stemness and progression, which deubiquitinated and stabilized YAP protein. The clinical data analysis implicated OTUB1 was higher expressed in gastric cancer, which correlated with YAP activity and poor survival. OUTB1 interacted with YAP protein via its OTU domain (Ovarian tumor domain) and deubiquitinated YAP at several lysine sites (K90, K280, K343, K494 and K497), which subsequently inhibited YAP degradation. Our study revealed a novel deubiquitinase of Hippo/YAP axis and one possible therapeutic target for YAP-driven gastric cancer., (© 2022. The Author(s).)

eIF3a (eukaryotic translation initiation factor 3a), a subunit of the eIF3 complex, has been suggested to play a regulatory role in protein synthesis and in cellular response to DNA-damaging treatments. S6K1 is an effector and a mediator of mTOR complex 1 (mTORC1) in regulating protein synthesis and integrating diverse signals into control of cell growth and response to stress. Here, we show that eIF3a regulates S6K1 activity by inhibiting mTORC1 kinase via regulating Raptor synthesis. The regulation of Raptor synthesis is via eIF3a interaction with HuR (human antigen R) and binding of the eIF3a-HuR complex to the 5'-UTR of Raptor mRNA. Furthermore, mTORC1 may mediate eIF3a function in cellular response to cisplatin by regulating synthesis of NER proteins and NER activity. Taken together, we conclude that the mTOR signaling pathway may also be regulated by translational control and mediate eIF3a regulation of cancer cell response to cisplatin by regulating NER protein synthesis., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Programmed death-ligand 1 (PD-L1) is an important immunosuppressive molecule highly expressed on the surface of cancer cells. IFNγ triggered cancer cell immunosuppression against CD8 + T cell surveillance via up-regulation of PD-L1. Histone demethylase JMJD2D promotes colorectal cancer (CRC) progression; however, the role of JMJD2D in cancer immune escape is unknown. Here, we report that both PD-L1 and JMJD2D are frequently overexpressed in human CRC specimens with a significant positive correlation. Genetic ablation of JMJD2D in CRC cells attenuated the expression of PD-L1 and stalled tumor growth in mice, accompanied by the elevated number and effector function of tumor infiltrating CD8 + T cells. Mechanistically, JMJD2D coactivated SP-1 to promote the expression of IFNGR1, which elevated STAT3-IRF1 signaling and promoted PD-L1 expression. Again, JMJD2D is a major coactivator for STAT3-IRF1 axis to enhance PD-L1 transcription in a demethylation activity dependent manner. Furthermore, pharmacological inhibition of JMJD2D conduced to improve the anti-tumor efficacy of PD-L1 antibody as demonstrated by slower tumor growth and higher infiltration and function of CD8 + T cells in the combination of JMJD2D inhibitor 5-c-8HQ and PD-L1 antibody group compared with monotherapy with either agent. These results demonstrate that JMJD2D promotes CRC immune escape by enhancing PD-L1 expression to inhibit the activation and tumor infiltration of CD8 + T cells; targeting JMJD2D has the potential role in promoting the efficacy of anti-PD-1/PD-L1 immunotherapy., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Transforming growth factor beta (TGFβ) superfamily signaling is a prime inducer of epithelial-mesenchymal transitions (EMT) that foster cancer cell invasion and metastasis, a major cause of cancer-related deaths. Yet, TGFβ signaling is frequently inactivated in human tumor entities including colorectal cancer (CRC) and pancreatic adenocarcinoma (PAAD) with a high proportion of mutations incapacitating SMAD4, which codes for a transcription factor (TF) central to canonical TGFβ and bone morphogenetic protein (BMP) signaling. Beyond its role in initiating EMT, SMAD4 was reported to crucially contribute to subsequent gene regulatory events during EMT execution. It is therefore widely assumed that SMAD4-mutant (SMAD4 mut ) cancer cells are unable to undergo EMT. Here, we scrutinized this notion and probed for potential SMAD4-independent EMT execution using SMAD4 mut CRC cell lines. We show that SMAD4 mut cells exhibit morphological changes, become invasive, and regulate EMT marker genes upon induction of the EMT-TF SNAIL1. Furthermore, SNAIL1-induced EMT in SMAD4 mut cells was found to be entirely independent of TGFβ/BMP receptor activity. Global assessment of the SNAIL1-dependent transcriptome confirmed the manifestation of an EMT gene regulatory program in SMAD4 mut cells highly related to established EMT signatures. Finally, analyses of human tumor transcriptomes showed that SMAD4 mutations are not underrepresented in mesenchymal tumor samples and that expression patterns of EMT-associated genes are similar in SMAD4 mut and SMAD4 wild-type (SMAD4 wt ) cases. Altogether, our findings suggest that alternative TFs take over the gene regulatory functions of SMAD4 downstream of EMT-TFs, arguing for considerable plasticity of gene regulatory networks operating in EMT execution. Further, they establish that EMT is not categorically precluded in SMAD4 mut tumors, which is relevant for their diagnostic and therapeutic evaluation., (© 2021. The Author(s).)

PP2A is a major serine/threonine phosphatase class involved in the regulation of cell signaling through the removal of protein phosphorylation. This class of phosphatases is comprised of different heterotrimeric complexes displaying distinct substrate specificities. The present review will focus on one specific heterocomplex, the phosphatase PP2A-B55. Herein, we will report the direct substrates of this phosphatase identified to date, and its impact on different cell signaling cascades. We will additionally describe its negative regulation by its inhibitors Arpp19 and ENSA and their upstream kinase Greatwall. Finally, we will describe the essential molecular features defining PP2A-B55 substrate specificity that confer the correct temporal pattern of substrate dephosphorylation. The main objective of this review is to provide the reader with a unique source compiling all the knowledge of this particular holoenzyme that has evolved as a key enzyme for cell homeostasis and cancer development., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

MicroRNAs (miRNAs) may modulate more than 60% of human coding genes and act as negative regulators, whereas long noncoding RNAs (lncRNAs) regulate gene expression on multiple levels by interacting with chromatin, functional proteins, and RNAs such as mRNAs and microRNAs. However, the crosstalk between HOTTIP lncRNA and miRNAs in leukemogenesis remains elusive. Using combined integrated analyses of global miRNA expression profiling and state-of-the-art genomic analyses of chromatin such as ChIRP-seq (HOTTIP binding in genomewide), ChIP-seq, and ATAC-seq, we found that some miRNA genes are directly controlled by HOTTIP. Specifically, the HOX cluster miRNAs (miR-196a, miR-196b, miR-10a, and miR-10b), located cis and trans, were most dramatically regulated and significantly decreased in HOTTIP -/- AML cells. HOTTIP bound to the miR-196b promoter and HOTTIP deletion reduced chromatin accessibility and enrichment of active histone modifications at HOX cluster-associated miRNAs in AML cells, whereas reactivation of HOTTIP restored miR gene expression and chromatin accessibility in the CTCF-boundary-attenuated AML cells. Inactivation of HOTTIP or miR-196b promotes apoptosis by altering the chromatin signature at the FAS promoter and increasing FAS expression. Transplantation of miR-196b knockdown MOLM13 cells in NSG mice increased overall survival of mice compared to wild-type cells transplanted into mice. Thus, HOTTIP remodels the chromatin architecture around miRNAs to promote their transcription and consequently represses tumor suppressors and promotes leukemogenesis., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

K-RAS mutation and molecular alterations of its surrogates function essentially in lung tumorigenesis and malignant progression. However, it remains elusive how tumor-promoting and deleterious events downstream of K-RAS signaling are coordinated in lung tumorigenesis. Here, we show that USP16, a deubiquitinase involved in various biological processes, functions as a promoter for the development of K-RAS-driven lung tumor. Usp16 deletion significantly attenuates K-ras G12D -mutation-induced lung tumorigenesis in mice. USP16 upregulation upon RAS activation averts reactive oxygen species (ROS)-induced p38 activation that would otherwise detrimentally influence the survival and proliferation of tumor cells. In addition, USP16 interacts with and deubiquitinates JAK1, and thereby promoting lung tumor growth by augmenting JAK1 signaling. Therefore, our results reveal that USP16 functions critically in the K-RAS-driven lung tumorigenesis through modulating the strength of p38 and JAK1 signaling., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

In response to oncogenic signals, Alternative Splicing (AS) regulators such as SR and hnRNP proteins show altered expression levels, subnuclear distribution and/or post-translational modification status, but the link between signals and these changes remains unknown. Here, we report that a cytosolic scaffold protein, IQGAP1, performs this task in response to heat-induced signals. We show that in gastric cancer cells, a nuclear pool of IQGAP1 acts as a tethering module for a group of spliceosome components, including hnRNPM, a splicing factor critical for the response of the spliceosome to heat-shock. IQGAP1 controls hnRNPM's sumoylation, subnuclear localisation and the relevant response of the AS machinery to heat-induced stress. Genome-wide analyses reveal that IQGAP1 and hnRNPM co-regulate the AS of a cell cycle-related RNA regulon in gastric cancer cells, thus favouring the accelerated proliferation phenotype of gastric cancer cells. Overall, we reveal a missing link between stress signals and AS regulation., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Endometrial carcinoma (EC) is the fourth-most common cancer in women in the United States, and generally carries a favorable prognosis. However, about 10% of EC patients have a rare and aggressive form, uterine serous papillary carcinoma (USPC), which carries a much higher mortality rate. The developmental transcription factor PAX8 is expressed in nearly 100% of USPCs. We show that PAX8 plays a critical antiapoptotic role in USPC and this role is established via transcriptional activation of two aberrant signaling pathways. First, PAX8 positively regulates mutated p53, and missense p53 mutations have an oncogenic gain of function effect. Second, PAX8 directly transcriptionally regulates p21, in a p53-independent manner, and p21 acquires a growth promoting role that is mediated via cytoplasmic localization of the protein. We propose that mutated p53 and cytoplasmic p21 can independently mediate the pro-proliferative role of PAX8 in USPC. In addition, we performed a genome-wide transcriptome analysis to detect pathways that are regulated by PAX8, and propose that metabolism and HIF-1alpha -related pathways are potential candidates for mediating the role of PAX8 in USPC. Taken together our findings demonstrate for the first time that PAX8 is an essential lineage marker in USPC, and suggest its mechanism of action., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Molecular alterations in the PI3K/AKT pathway occur frequently in hormone receptor-positive breast tumors. Patients with ER-positive, HER2-negative metastatic breast cancer are often treated with CDK4/6 inhibitors such as palbociclib in combination with endocrine therapy. Although this is an effective regimen, most patients ultimately progress. The purpose of this study was identifying synthetic lethality partners that can enhance palbociclib's antitumor efficacy in the presence of PIK3CA/AKT1 mutations. We utilized a barcoded shRNA library to determine critical targets for survival in isogenic MCF7 cells with PIK3CA/AKT1 mutations. We demonstrated that the efficacy of palbociclib is reduced in the presence of PIK3CA/AKT1 mutations. We also identified that the downregulation of discoidin domain receptor 1 (DDR1) is synthetically lethal with palbociclib. DDR1 knockdown and DDR1 pharmacological inhibitor decreased cell growth and inhibited cell cycle progression in all cell lines, while enhanced the sensitivity of PIK3CA/AKT1 mutant cells to palbociclib. Combined treatment of palbociclib and 7rh further induced cell cycle arrest in PIK3CA/AKT1 mutant cell lines. In vivo, 7rh significantly enhanced palbociclib's antitumor efficacy. Our data indicates that DDR1 inhibition can augment cell cycle suppressive effect of palbociclib and could be effective strategy for targeted therapy of ER-positive, HER2-negative breast cancers with PI3K pathway activation.

Numerous studies suggest an important role for copy number alterations (CNAs) in cancer progression. However, CNAs of long intergenic noncoding RNAs (lincRNAs) in ovarian cancer (OC) and their potential functions have not been fully investigated. Here, based on analysis of The Cancer Genome Atlas (TCGA) database, we identified in this study an oncogenic lincRNA termed LINC00662 that exhibited a significant correlation between its CNA and its increased expression. LINC00662 overexpression is highly associated with malignant features in OC patients and is a prognostic indicator. LINC00662 significantly promotes OC cell proliferation and metastasis in vitro and in vivo. Mechanistically, LINC00662 is stabilized by heterogeneous nuclear ribonucleoprotein H1 (HNRNPH1). Moreover, LINC00662 exerts oncogenic effects by interacting with glucose-regulated protein 78 (GRP78) and preventing its ubiquitination in OC cells, leading to activation of the oncogenic p38 MAPK signaling pathway. Taken together, our results define an oncogenic role for LINC00662 in OC progression mediated via GRP78/p38 signaling, with potential implications regarding therapeutic targets for OC., (© 2021. The Author(s).)

Dickkopf1 (DKK1) is overexpressed in various cancers and promotes cancer cell proliferation by binding to cytoskeleton-associated protein 4 (CKAP4). However, the mechanisms underlying DKK1 expression are poorly understood. RNA sequence analysis revealed that expression of the transcription factor forkhead box M1 (FOXM1) and its target genes concordantly fluctuated with expression of DKK1 in pancreatic ductal adenocarcinoma (PDAC) cells. DKK1 knockdown decreased FOXM1 expression and vice versa in PDAC and esophageal squamous cell carcinoma (ESCC) cells. Inhibition of either the DKK1-CKAP4-AKT pathway or the ERK pathway suppressed FOXM1 expression, and simultaneous inhibition of both pathways showed synergistic effects. A FOXM1 binding site was identified in the 5'-untranslated region of the DKK1 gene, and its depletion decreased DKK1 expression and cancer cell proliferation. Clinicopathological and database analysis revealed that PDAC and ESCC patients who simultaneously express DKK1 and FOXM1 have a poorer prognosis. Multivariate analysis demonstrated that expression of both DKK1 and FOXM1 is the independent prognostic factor in ESCC patients. Although it has been reported that FOXM1 enhances Wnt signaling, FOXM1 induced DKK1 expression independently of Wnt signaling in PDAC and ESCC cells. These results suggest that DKK1 and FOXM1 create a positive feedback loop to promote cancer cell proliferation.

Research over the past decade has suggested important roles for pseudogenes in glioma. This study aimed to show that pseudogene PRELI domain-containing 1 pseudogene 6 (PRELID1P6) promotes glioma progression. Aberrant expression of genes was screened using The Cancer Genome Atlas database. We found that mRNA level of PRELID1P6 was highly upregulated in glioma and was associated with a shorter survival time. Functional studies showed that the knockdown of PRELID1P6 decreased cell proliferation, sphere formation, and clone formation ability and blocked the cell cycle transition at G0/G1, while overexpression of PRELID1P6 had the opposite effects. Mechanistically, knockdown of PRELID1P6 changed the cellular localization of heterogeneous nuclear ribonucleoprotein H1 (hnRNPH1) from nucleus to cytoplasm, which promoted ubiquitin-mediated degradation of hnRNPH1. RNA-sequence and gene set enrichment analysis suggested that knockdown of PRELID1P6 regulates the apoptosis signaling pathway. Western blotting showed that PRELID1P6 increased TRF2 expression by hnRNPH1-mediated alternative splicing effect and activated the Akt/mTOR pathway. Furthermore, Akt inhibitor MK2206 treatment reversed the oncogenic function of PRELID1P6. PRELID1P6 was also found to be negatively regulated by miR-1825. Our result showed that PRELID1P6 promotes glioma progression through the hnHNPH1-Akt/mTOR pathway. These findings shed new light on the important role of PRELID1P6 as a novel oncogene for glioma.

Prostate cancer (PC) is the second most common cancer with limited treatment option in males. Although the reactivation of embryonic signals in adult cells is one of the characteristics of cancer, the underlying protein degradation mechanism remains elusive. Here, we show that the molecular chaperone GRP75 is a key player in PC cells by maintaining the protein stability of SIX1, a transcription factor for embryonic development. Mechanistically, GRP75 provides a platform to recruit the deubiquitinating enzyme USP1 to inhibit K48-linked polyubiquitination of SIX1. Structurally, the C-terminus of GRP75 (433-679 aa) contains a peptide binding domain, which is required for the formation of GRP75-USP1-SIX1 protein complex. Functionally, pharmacological or genetic inhibition of the GRP75-USP1-SIX1 protein complex suppresses tumor growth and overcomes the castration resistance of PC cells in vitro and in xenograft mouse models. Clinically, the protein expression of SIX1 in PC tumor tissues is positively correlated with the expression of GRP75 and USP1. These new findings not only enhance our understanding of the protein degradation mechanism, but also may provide a potential way to enhance the anti-cancer activity of androgen suppression therapy.

Lung cancer is the leading cause of cancer-related death worldwide. Glypican-5 (GPC5) is a member of heparan sulfate proteoglycans, and its biological importance in initiation and progression of lung cancer remains controversial. In the present study, we revealed that GPC5 transcriptionally enhanced the expression of CTDSP1 (miR-26b host gene) via AhR-ARNT pathway, and such up-regulation of CTDSP1 intracellularly contributed to the inhibited proliferation of lung cancer cells. Moreover, exosomes derived from GPC5-overexpressing human lung cancer cells (GPC5-OE-derived exosomes) had an extracellular repressive effect on human lymphatic endothelial cells (hLECs), leading to decreased tube formation and migration. Comparison between GPC5-WT- and GPC5-OE-derived exosomes showed that miR-26b (embedded within introns of CTDSP1 gene) was significantly up-regulated in GPC5-OE-derived exosomes and critical to the influence on hLECs. On the mechanism, we demonstrated that miR-26b transferred into hLECs directly targeted to PTK2 3'-UTR and led to PTK2 down-regulation, resulting in defects in tube formation and migration of hLECs. By uncovering the regulation network among GPC5, miR-26b, miR-26b host gene (CTDSP1), and target gene (PTK2), our findings demonstrated that GPC5 functioned as a tumor suppressor in human lung cancer.

Emerging evidences suggest that long noncoding RNA (lncRNA) plays a vital role in tumorigenesis and cancer progression. Here, the aim of this study is to investigate the biological function of long intervening noncoding RNA Linc00284 in colorectal cancer (CRC). The expression levels of Linc00284, miR-27a and c-Met were evaluated by qPCR and/or Western blotting. Immunohistochemistry was used to detect the expression of Ki67 and Phh3 in tumor tissues. The interaction between Linc00284, miR-27a and c-Met was validated by luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Cell function experiments, including CCK-8, wound-healing and transwell invasion assays, were conducted. The in vivo studies were performed with the subcutaneous tumor xenograft mouse models. Our findings reveal that Linc00284 is upregulated in CRC tissues and colorectal cancer cell lines HCT116 and SW480 in comparison with corresponding para-carcinoma tissues and human fetal colonic mucosa cells FHC. High expression of Linc00284 in tumor tissues is associated with tumor metastasis and predicts a poor clinical outcome in CRC patients. Serum Linc00284 is increased, while miR-27a is decreased in CRC patients compared to healthy controls. ROC curve analysis indicates that serum Linc00284 and miR-27a produce the area under the curve (AUC) value of at 0.8151 and 0.7316 in patients with colorectal cancer compared to healthy individuals, respectively. Additionally, results in vitro and in vivo experiments suggest that Linc00284 silencing significantly suppresses CRC cell proliferation and/or invasion. Mechanistically, Linc00284 promotes c-Met expression by acting as miR-27a sponge, leading to the activation of downstream signaling pathways, thereby causing malignant phenotypes of CRC cells. Taken together, Linc00284 exhibits oncogenic function and the disturbance of Linc00284/miR-27a/c-Met regulatory axis contributes to CRC progression, providing new insight into the pathogenesis of colorectal cancer. Importantly, the expression levels of serum Linc00284 and miR-27a may serve as clinical biomarkers for CRC diagnosis.

Glioma is the most common and fatal primary malignant brain tumor. Glioma stem cells (GSCs) may be an important factor in glioma cell proliferation, invasion, chemoradiotherapy tolerance, and recurrence. Therefore, discovering novel GSCs related circular RNAs (circRNAs) may finds out a prospective target for the treatment of glioma. A novel circRNA-CHAF1A (circCHAF1A) was first found in our study. CircCHAF1A was overexpressed in glioma and related to the low survival rate. Functionally, it was found that no matter in vitro or in vivo, circCHAF1A can facilitate the proliferation and tumorigenesis of TP53wt GSCs. Mechanistically, circCHAF1A upregulated transcription factor HOXC8 expression in GSCs through miR-211-5p sponging. Then, HOXC8 can transcriptionally upregulate MDM2 expression and inhibited the antitumor effect of p53. Furtherly, the RNA binding protein FMR1 can bind to and promoted the expression of circCHAF1A via maintaining its stability, while HOXC8 also transcribed the FMR1 expression to form a feedback loop, which may be involved in the malignant transformation of glioma. The novel feedback loop among FMR1, circCHAF1A, miR-211-5p, and HOXC8 in GSCs can facilitate the proliferation and tumorigenesis of glioma and GSCs. It also provided a helpful biomarker for diagnosis and prognostic evaluation of glioma and may be applied to molecular targeted therapy.

Presence of inflammatory factors in the tumor microenvironment is well-documented yet their specific role in tumorigenesis is elusive. The core inflammatory pathways like the Toll-Like Receptor (TLR) and the Tumor Necrosis Factor (TNF) pathway are conserved in Drosophila. We induced GFP-marked epithelial tumors by expressing activated oncogenic forms of Ras V12 or Yorkie (Yki 3SA , mammalian YAP) in scribble deficient cells (scrib RNAi , mammalian SCRIB) to study the role of inflammatory factors in tumorigenesis. Similar to Ras V12 scrib RNAi , we found that Yki 3SA scrib RNAi form invasive neoplastic lethal tumors that induce a systemic inflammatory response. We identified Cactus (Cact, mammalian IκBα), the negative regulator of TLR, as a key player in tumor growth. Cact accumulates in the cytoplasm in Drosophila tumor models, similar to squamous cell carcinoma in mice models and human patients where cytoplasmic IκBα favors oncogenic transformation. Further, cact is transcriptionally upregulated in tumors, and downregulation of Cact affects tumor growth. We investigated if TLR or TNF pathway affect tumor growth through activation of Jun N-terminal Kinase (JNK) pathway and its target Matrix Metalloprotease1 (MMP1). Genetically manipulating levels of TLR components or TNF receptors showed that Cact acts upstream of JNK signaling and regulates JNK via a non-canonical mechanism during tumorigenesis. Further, Hippo coactivator Yki transcriptionally regulates cact expression, and downregulation of Yki or Cact is sufficient to cause downregulation of JNK-mediated signaling that promotes tumorigenesis. Here, we report a link between Hippo, IκBα and JNK signaling that may induce inflammation and innate immune response in tumorigenesis.

CircRNAs play essential roles in various physiological processes and involves in many diseases, in particular cancer. Global downregulation of circRNA expression has been observed in hepatocellular carcinoma (HCC) in many studies. Previous studies revealed that the pre-mRNA 3' end processing complex participates in circRNA cyclization and plays an important role in HCC tumorigenesis. Therefore, we explored the role of CPSF4, for 3' end formation and cleavage, in circRNA formation. Clinical research has shown that CPSF4 expression is upregulated in HCC and that high expression of CPSF4 is associated with poor prognosis in HCC patients. Mechanistic studies have demonstrated that CPSF4 reduces the levels of circRNAs, which possess a polyadenylation signal sequence and this decrease in circRNAs reduces the accumulation of miRNA and disrupts the miRNA-mediated gene silencing in HCC. Experiments in cell culture and xenograft mouse models showed that CPSF4 promotes the proliferation of HCC cells and enhances tumorigenicity. Moreover, CPSF4 antagonizes the tumor suppressor effect of its downstream circRNA in HCC. In summary, CPSF4 acts as an oncogene in HCC through circRNA inhibition and disruption of miRNA-mediated gene silencing.