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Radiotherapy plays an essential role in the treatment of head and neck squamous cell carcinoma (HNSCC), yet radioresistance remains a major barrier to therapeutic efficacy. A better understanding of the predominant pathways determining radiotherapy response could help develop mechanism-informed therapies to improve cancer management. Here we report that radioresistant HNSCC cells exhibit increased tumor aggressiveness. Using unbiased proteome profiler antibody arrays, we identify that upregulation of c-Met phosphorylation is one of the critical mechanisms for radioresistance in HNSCC cells. We further uncover that radioresistance-associated HNSCC aggressiveness is effectively exacerbated by c-Met but is suppressed by its genetic knockdown and pharmacologic inactivation. Mechanistically, the resulting upregulation of c-Met promotes elevated expression of plexin domain containing 2 (PLXDC2) through activating ERK1/2-ELK1 signaling, which in turn modulates cancer cell plasticity by epithelial–mesenchymal transition (EMT) induction and enrichment of the cancer stem cell (CSC) subpopulation, leading to resistance of HNSCC cells to radiotherapy. Depletion of PLXDC2 overcomes c-Met–mediated radioresistance through reversing the EMT progress and blunting the self-renewal capacity of CSCs. Therapeutically, the addition of SU11274, a selective and potent c-Met inhibitor, to radiation induces tumor shrinkage and limits tumor metastasis to lymph nodes in an orthotopic mouse model. Collectively, these significant findings not only demonstrate a novel mechanism underpinning radioresistance-associated aggressiveness but also provide a possible therapeutic strategy to target radioresistance in patients with HNSCC. Significance: This work provides novel insights into c-Met-PLXDC2 signaling in radioresistance-associated aggressiveness and suggests a new mechanism-informed therapeutic strategy to overcome failure of radiotherapy in patients with HNSCC.

Effect of PLXDC2 knockdown on colony formation of radioresistant CAL27 and HN6 cells determined on Day 12 following 4 Gy IR exposure

Radiotherapy plays an essential role in the treatment of head and neck squamous cell carcinoma (HNSCC), yet radioresistance remains a major barrier to therapeutic efficacy. A better understanding of the predominant pathways determining radiotherapy response could help develop mechanism-informed therapies to improve cancer management. Here we report that radioresistant HNSCC cells exhibit increased tumor aggressiveness. Using unbiased proteome profiler antibody arrays, we identify that upregulation of c-Met phosphorylation is one of the critical mechanisms for radioresistance in HNSCC cells. We further uncover that radioresistance-associated HNSCC aggressiveness is effectively exacerbated by c-Met but is suppressed by its genetic knockdown and pharmacologic inactivation. Mechanistically, the resulting upregulation of c-Met promotes elevated expression of plexin domain containing 2 (PLXDC2) through activating ERK1/2-ELK1 signaling, which in turn modulates cancer cell plasticity by epithelial–mesenchymal transition (EMT) induction and enrichment of the cancer stem cell (CSC) subpopulation, leading to resistance of HNSCC cells to radiotherapy. Depletion of PLXDC2 overcomes c-Met–mediated radioresistance through reversing the EMT progress and blunting the self-renewal capacity of CSCs. Therapeutically, the addition of SU11274, a selective and potent c-Met inhibitor, to radiation induces tumor shrinkage and limits tumor metastasis to lymph nodes in an orthotopic mouse model. Collectively, these significant findings not only demonstrate a novel mechanism underpinning radioresistance-associated aggressiveness but also provide a possible therapeutic strategy to target radioresistance in patients with HNSCC.Significance:This work provides novel insights into c-Met-PLXDC2 signaling in radioresistance-associated aggressiveness and suggests a new mechanism-informed therapeutic strategy to overcome failure of radiotherapy in patients with HNSCC.

The primer sequences for qRT-PCR assays.

An electrochemical detection method was developed to examine the ability of removing superoxide free radical (O2ââ,¬â¢-) on electrochemical station. Cx represents certain current in peak (potential=0.7V), C0 represents control current in peak (potential=0.7V), and the current changes % = (Cx-C0)/C0Ãâ€"100%.

The tumor microenvironment induces endoplasmic reticulum (ER) stress in tumor cells, an event that can promote progression, but it is unknown how tumor cells adapt to this stress. In this study, we show that the fibroblast growth factor FGF19, a gene frequently amplified in hepatocellular carcinoma (HCC), facilitates a survival response to ER stress. Levels of FGF19 expression were increased in stressed HCC cells in culture and in a mouse xenograft model. Induction of ER stress required the transcription factor ATF4, which directly bound the FGF19 promoter. In cells where ER stress was induced, FGF19 overexpression promoted HCC cell survival and increased resistance to apoptosis, whereas FGF19 silencing counteracted these effects. Mechanistic investigations implicated glycogen synthase kinase-3β (GSK3β) in regulating nuclear accumulation of the stress-regulated transcription factor Nrf2 activated by FGF19. Our findings show how FGF19 provides a cytoprotective role against ER stress by activating a FGFR4–GSK3β–Nrf2 signaling cascade, with implications for targeting this signaling node as a candidate therapeutic regimen for HCC management. Cancer Res; 77(22); 6215–25. ©2017 AACR.

Background Metastasis is most often the root cause of cancer-related death. Human short stature homeobox 2 (SHOX2), a homeodomain transcription factor, is a novel inducer of epithelial-to-mesenchymal transition in breast cancer cells, though its exact role and underlying mechanisms in metastasis are not well understood. Methods TCGA analysis was performed to identify the clinical relevance of SHOX2 in breast cancer. Gene depletion was achieved by short hairpin RNA and small interfering RNA. Molecular regulations and alterations were assessed by Western blotting, immunoprecipitation, immunohistochemistry, qRT-PCR, chromatin immunoprecipitation coupled with qPCR (ChIP-qPCR), and ChIP/re-ChIP. The impact of SHOX2 signaling on tumor growth and metastasis was evaluated in orthotopic breast tumor mice. Results The expression level of SHOX2 is strongly associated with poor distant metastasis-free survival in breast cancer patients and inactivation of SHOX2 suppresses breast tumor growth and metastasis in mice. In breast cancer cells, SHOX2 directly activates Wiskott-Aldridge syndrome protein family member 3 (WASF3), a metastasis-promoting gene, at the transcriptional level, leading to a significant increase in metastatic potential. Mechanistically, SHOX2 activates signal transducer and activator of transcription 3 (STAT3) and recruits it to the WASF3 promoter, where STAT3 cooperates with SHOX2 to form a functional immunocomplex to promote WASF3 transcriptional activity in breast cancer cells. WASF3 knockdown abrogates SHOX2-induced metastasis, but not SHOX2-dependent tumorigenesis. Conclusions These findings provide a critical link between the SHOX2-STAT3-WASF3 signaling axis and metastasis and suggest that the targeting of this signaling node may represent a valuable alternative strategy for combating breast cancer metastasis.

Background Immune-related adverse events (irAEs) are a common phenomenon in cancer patients treated with immune checkpoint inhibitors (ICIs). Surprisingly, the toxicity burdens of these irAEs have not been illustrated clearly. In this study, we analyzed irAEs for seven FDA-approved ICIs in cancer treatment to show the pattern of toxicity burden among cancer patients. Methods irAEs associated with seven FDA-approved ICIs, including three PD-1 inhibitors (cemiplimab, nivolumab and pembrolizumab), three PD-L1 inhibitors (atezolizumab, avelumab and durvalumab), and one CTLA-4 inhibitor (ipilimumab), were analyzed based on data from 149,303 reported cases (from January 1, 2015 to June 30, 2022) collected from the FDA Adverse Events Reporting System (FAERS) public dashboard. Proportions of serious irAEs and correlations with tumor type, age and sex were assessed via R package and GraphPad software. Results irAEs related to anti-PD-1 ICIs required less hospital care resources compared with anti-PD-L1 and anti-CTLA-4 ICIs. Patients treated with pembrolizumab had relatively fewer serious cases. Treatment with ICIs led to the highest probability of serious irAEs in patients with lung cancer. ‘Respiratory, thoracic and mediastinal disorders’ and ‘gastrointestinal disorders’ were the two most common groups of disorders caused by the seven ICIs studied. ‘Cardiac disorders’ was the main type of disorders caused by these ICIs in cancer patients aged 65–85, while ‘reproductive system and breast disease’ was the main type of disorder in cancer patients aged 18–64. ‘Respiratory, thoracic, mediastinal diseases’ and ‘reproductive system and breast diseases’ were the main types of disorders associated with treatment with these ICIs in male and female patients, respectively. Conclusion Tissue and organ toxicities of ICIs are age and sex specific. There are risks of respiratory and urinary system toxicity in male patients and reproductive system toxicity in female patients treated with the ICIs studied. Future studies on the toxicity burden of ICIs should incorporate age and sex differences to better understand the relevance of ICI toxicity burden to human immune function to develop appropriate tumor immune and therapeutic intervention strategies.

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment landscape for multiple cancers, demonstrating effective and durable responses and becoming the standard of care for a variety of malignancies. However, ICI-based treatment has resulted in the rise of unique immune-related adverse events (irAEs). To date, very little information is available on the frequency, significance, and management of single-organ or multiorgan irAEs in clinic. In this study, the irAEs associated with the treatment of seven FDA-approved ICIs, including three PD-1 inhibitors (cemiplimab, nivolumab and pembrolizumab), three PD-L1 inhibitors (atezolizumab, avelumab and durvalumab), and one CTLA4 inhibitor (ipilimumab), were analyzed based on the data of 149,303 report cases (January 1, 2015 - June 30, 2022) collected from FDA Adverse Events Reporting System (FAERS) public dashboard. Our data reveal that irAEs associated with the treatment of anti-PD-1 ICIs (e.g., pembrolizumab) require less hospital care resources compared with anti-PD-L1 and anti-CTLA4 ICIs. Tissue and organ toxicity of ICIs are age and gender specific. ‘Cardiac disorders’ is the main disorder caused by these ICIs in cancer patients aged 65-85, while ‘reproductive system and breast disease’ is the main disorder in cancer patients aged 18-64. There are risks of respiratory and urinary system toxicity in male patients and reproductive system toxicity in female patients when they receive the treatment of ICIs. Studies such as this one provide the statistical data for understanding patients at risk of developing irAEs, which will underscore the importance of further exploring research strategies to predict, detect, and mitigate toxicities from ICIs. Citation Format: Fan Yang, Chloe Shay, Zhaohui Qin, Nabil Saba, Yong Teng. Total toxicity burden of FDA approved immune checkpoint inhibitors in USA. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4387.

The development of radioresistance in head and neck squamous cell carcinoma (HNSCC) remains a significant problem in cancer treatment, contributing to the lack of improvement in survival trends in the past decades. One of the clinical challenges is that radioresistance often promotes tumor aggressiveness. However, the underlying mechanisms and molecular determinants are largely unknown. We report here that radioresistance-associated HNSCC aggressiveness is effectively exacerbated by c-Met but can be suppressed by its genetic knockdown and pharmacological inactivation. Through unbiased RNAseq data, we further uncovered that the resulting upregulation of c-Met signaling increases the expression of PLXDC2. a critical gene associated with the tumor microenvironment. Mechanistically, PLXDC2 is upregulated in radioresistant HNSCC cells through c-Met mediated activation of ERK1/2-ELK1 signaling cascade. Most importantly, PLXDC2 modulates cancer cell plasticity by inducing epithelial-mesenchymal transition (EMT) and the emergence of cancer stem cell (CSC) subpopulation. Additionally, depletion of PLXDC2 overcomes c-Met-mediated radioresistance by reversing the EMT progress and blunting the self-renewal capacity of CSCs. Therapeutically, a combination of the c-Met selective inhibitor SU11274 with radiation remarkably induces tumor shrinkage and constrains tumor metastasis to lymph nodes in vivo. Our study is novel in being the first to explore the role and mechanism of the c-Met-PLXDC2 axis in radioresistance-associated HNSCC aggressiveness and the first to our knowledge to evaluate how to take advantage of blocking this signaling to overcome radioresistance in preclinical mouse models of HNSCC. Citation Format: Fanghui Chen, Liwei Lang, Chloe Shay, Georgia Chen, Nabil Saba, Yong Teng. Met confers radioresistance-associated aggressiveness through enhancing PLXDC2-mediated cancer stem cell plasticity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5793.

The identification and development of reagents that can limit preferential metabolic effectors in tumors as well as trigger unfavorable tumoral metabolic cues is of tremendous importance for suppressing malignancy. However, insufficient blocking of critical metabolic dependencies of cancer allows the development of metabolic bypasses, which significantly dampens therapeutic benefits of selective agents that target a single metabolic enzyme or pathway. We report here that head and neck squamous cell carcinoma (HNSCC) cells display strong addiction to glutamine. Devimistat, a novel lipoate analog, redirects cellular activity towards tumor-promoting glutaminolysis, leading to low anticancer efficacy in HNSCC cells. Mechanistically, devimistatinhibits the tricarboxylic acid cycle by blocking the enzyme activities of pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, which upregulates GLS1 and eventually promotes the compensatory role of glutaminolysis in cancer cell survival. Most importantly, the addition of a GLS1 inhibitor CB-839 to devimistat treatment abrogates the metabolic dependency of HNSCC cells on glutamine, achieving a synergistic anticancer effect in glutamine-addicted HNSCC. These novel and significant findings could lay a scientific foundation for developing more effective treatments targeting the metabolic requirements of HNSCC. Citation Format: Liwei Lang, Fang Wang, Chloe Shay, Yonggang Ke, Nabil Saba, Yong Teng. Inhibition of glutaminolysis overcomes metabolic adaptation to devimistat treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3026.

Targeting mitochondria as a cancer therapeutic strategy has attracted more and more attention in the recent years. ATAD3A is identified as a nuclear-encoded mitochondrial enzyme that regulates mitochondrial dynamics, cholesterol metabolism, and signal transduction. However, its impact and underlying regulatory mechanisms in cancers remain to be determined. We report here that ATAD3A is highly expressed in head and neck squamous cell carcinoma (HNSCC), where it plays a critical role in favoring tumor progression. Loss of ATAD3A expression dramatically incudes tumor regression in orthotopic tongue tumor-bearing mice, whereas gain of ATAD3A expression produces the opposite effects. Mechanistically, ATAD3A binds to ERK1/2 at HNSCC cell mitochondria in the presence of VDAC1, and this interaction is essential for the activation of mitochondrial ERK1/2 signaling. Most importantly, the ATAD3A-ERK1/2 signaling axis enhances HNSCC development in a Ras-independent manner and, thus, tumor suppression is more effectively achieved when ATAD3A and Ras signaling pathways are co-inhibited. These novel findings highlight the importance of activation of ATAD3A-ERK1/2 axis in cancer progression and suggest that combined targeting of ATAD3A and Ras signaling could potentiate anticancer activity for HNSCC treatment. Citation Format: Liwei Lang, Reid Loveless, Zhaohui Qin, Peng Qiu, Chloe Shay, Yong Teng. ATAD3A enhances head and neck cancer malignancy via mitochondrial ERK1/2 signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 88.

The fibroblast growth factor 19 gene FGF19 has previously been reported to be amplified in several cancer types and encodes for a key autocrine signaler known to promote tumorigenic growth. Thus, it is imperative to understand which cancers are oncogenically addicted to FGF19 amplification as well as the role it serves in these cancer types. We report for the first time high FGF19 amplification in head and neck squamous cell carcinomas (HNSCC), which is associated with increased autocrine secretion of FGF19 and poor patient outcome in HNSCC. FGF19 amplification corresponded with constitutive activation of FGF receptor 4 (FGFR4)-dependent ERK/AKT-p70S6K-S6 signaling activation in HNSCC cells, and addition of human recombinant FGF19 could promote cell proliferation and soft agar colony formation in HNSCC cells with low FGF19 expression through activation of FGFR4 and downstream signaling cascades. In contrast, FGF19 knockout counteracts the observed effects in HNSCC cells carrying high endogenous FGF19, with knockout of FGF19 significantly suppressing tumor growth in an orthotopic mouse model of HNSCC. Collectively, this study demonstrates that FGF19 gene amplification corresponds with an increased dependency upon FGF19/FGFR4 autocrine signaling in HNSCC, revealing a therapeutic target for this cancer type.

The majority of RNA transcripts are non-coding RNA (ncRNA) transcripts with lengths exceeding 200 nucleotides that are not translated into protein. Unlike microRNAs (miRNAs), long ncRNAs (lncRNAs) are not confined to a single mechanism of action but have a large and diverse role in biological processes as they can function as transcription regulators, decoys, scaffolds, and enhancer RNAs. Currently, many lncRNA molecules are under investigation for their role in tumorigenesis, metastasis, and prognosis in different types of cancer. This review not only summarizes the characteristics and functions of lncRNAs but also discusses the therapeutic implications and applications of lncRNAs with roles associated with head and neck cancer. Our aim is to pinpoint the potential way to perturb specific lncRNAs for future therapeutic use.

Background There is no consensus about the effective dosages of melatonin in cancer management, thus, it is imperative to fully understand the dose-dependent responsiveness of cancer cells to melatonin and the underlying mechanisms. Methods Head and neck squamous cell carcinoma (HNSCC) cells with or without melatonin treatment were used as a research platform. Gene depletion was achieved by short hairpin RNA, small interfering RNA, and CRISPR/Cas9. Molecular changes and regulations were assessed by Western blotting, quantitative RT-PCR (qRT-PCR), immunohistochemistry, and chromatin Immunoprecipitation coupled with qPCR (ChIP-qPCR). The therapeutic efficacy of FGF19/FGFR4 inhibition in melatonin-mediated tumor growth and metastasis was evaluated in orthotopic tongue tumor mice. Results The effect of melatonin on controlling cell motility and metastasis varies in HNSCC cells, which is dose-dependent. Mechanistically, high-dose melatonin facilitates the upregulation of FGF19 expression through activating endoplasmic stress (ER)-associated protein kinase RNA-like endoplasmic reticulum kinase (PERK)-Eukaryotic initiation factor 2 alpha (eIF2α)-activating transcription factor 4 (ATF4) pathway, which in turn promotes FGFR4-Vimentin invasive signaling and attenuates the role of melatonin in repressing metastasis. Intriguingly, following long-term exposure to high-dose melatonin, epithelial HNSCC cells revert the process towards mesenchymal transition and turn more aggressive, which is enabled by FGF19/FGFR4 upregulation and alleviated by genetic depletion of the FGF19 and FGFR4 genes or the treatment of FGFR4 inhibitor H3B-6527. Conclusions Our study gains novel mechanistic insights into melatonin-mediated modulation of FGF19/FGFR4 signaling in HNSCC, demonstrating that activating this molecular node confines the role of melatonin in suppressing metastasis and even triggers the switch of its function from anti-metastasis to metastasis promotion. The blockade of FGF19/FGFR4 signaling would have great potential in improving the efficacy of melatonin supplements in cancer treatment.

Background: Development of radioresistance in oral squamous cell carcinoma (OSCC) remains a significant problem in cancer treatment, contributing to the lack of improvement in survival trends in recent decades. Effective strategies to overcome radioresistance are necessary to improve the therapeutic outcomes of radiotherapy in OSCC patients. Methods: Cells and xenograft tumors were irradiated using the Small Animal Radiation Research Platform. AKT inhibitor capivasertib (AZD5363) was encapsulated into cathepsin B-responsible nanoparticles (NPs) for tumor-specific delivery. Cell viability was measured by alamarBlue, cell growth was determined by colony formation and 3D culture, and apoptosis was assessed by flow cytometry with the staining of Fluorescein isothiocyanate (FITC) Annexin V and PI. An orthotopic tongue tumor model was used to evaluate the in vivo therapeutic effects. The molecular changes induced by the treatments were assessed by Western blotting and immunohistochemistry. Results: We show that upregulation of AKT signaling is the critical mechanism for radioresistance in OSCC cells, and AKT inactivation by a selective and potent AKT inhibitor capivasertib results in radiosensitivity. Moreover, relative to irradiation (IR) alone, IR combined with the delivery of capivasertib in association with tumor-seeking NPs greatly enhanced tumor cell repression in 3D cell cultures and OSCC tumor shrinkage in an orthotopic mouse model. Conclusions: These data indicate that capivasertib is a potent agent that sensitizes radioresistant OSCC cells to IR and is a promising strategy to overcome failure of radiotherapy in OSCC patients.

With the development of new materials and technologies, it is possible to access gene function and drug metabolism using a three-dimensional (3D) cell culture system, which is more suitable for mimicking the in vivo microenvironment of cultured tumor cells ex vivo. SeedEZ is a novel and versatile tool that allows culturing of different types of cells with user convenience and in a desired sequence. This system provides a bridge between traditional 2D culture and animal experiments. Here, we provide two examples demonstrating how to evaluate cancer cell growth by the SeedEZ 3D scaffold and cancer cell invasion by the SeedEZ 3D ring, in order to promote understanding of the necessity of this novel cell culture system.

The functional relationship between apoptosis and autophagy in anticancer drug treatment is extremely complex, and the molecular machinery is obscure. This study aims to investigate the efficacy of CYT997, a novel microtubule-disrupting agent, in head and neck squamous cell carcinomas (HNSCCs) and complete the autophagy-apoptosis puzzle involved in drug action. We report here that CYT997 exhibits anticancer activity by triggering oxidative stress-associated apoptosis in HNSCC cells. Interestingly, upregulation of autophagy by mTOR-dependent pathways appears to have a cytoprotective role in preventing apoptosis by inhibiting CYT997-induced excessively high levels of reactive oxygen species (ROS). Blockade of autophagy by ATG7 depletion or addition of autophagy inhibitor hydroxychloroquine (HCQ) sensitizes HNSCC cells to CYT997 as evidenced by enhanced ROS-associated apoptosis. Moreover, HCQ exhibits a good synergism with CYT997 on induction of apoptosis in HNSCC xenografts without cytotoxicity, suggesting combined treatment of CYT997 with autophagy inhibitors would increase the anticancer efficacy of CYT997. These findings unveil the importance of ROS in crosstalk between autophagy and apoptosis in CYT997 treatment, raising concerns that genetic or pharmacologic blockade of autophagy should be considered in the design of new therapeutics for HNSCC. • CYT997 exhibits anticancer activity by induction of ROS-associated apoptosis. • mTOR-dependent cytoprotective autophagy prevents CYT997-induced apoptosis. • Blockade of autophagy augments CYT997 efficacy by enhanced ROS-associated apoptosis. • Combination of autophagy inhibitors with CYT997 is more effective against HNSCC.

Background Src, an oncoprotein that drives progression of head and neck squamous cell carcinoma (HNSCC), is commonly hyperactivated in this disease. Unfortunately, the clinical benefit of targeting Src is significantly dampened in HNSCC patients, because the cytotoxic effects of anti-Src therapy and tumor resistance to it are less predictable. Thus, understanding the mechanism of tumor resistance to Src inhibition and seeking a way to overcome it are warranted. Methods Dual drug-loaded nanoparticles (NPs) were developed to co-deliver Src inhibitor saracatinib (AZD0530) and AKT inhibitor capivasertib (AZD5363) into the same population of tumor cells. An orthotopic tongue tumor model was generated to evaluate the in vivo therapeutic effects. Cell growth was determined by CellTiter-Glo® Luminescent Cell Viability Kit, colony formation, and 3D culture, and tumor growth was determined by bioluminescence and tumor size. The molecular changes induced by the treatments were assessed by Western blotting and immunohistochemistry. Results Capivasertib inactivated the AKT-S6 signaling and re-sensitized saracatinib-resistant HNSCC cells to saracatinib. Combination of capivasertib with saracatinib suppressed HNSCC growth more efficiently than either drug alone. Cathepsin B-sensitive NPs for co-delivering saracatinib and capivasertib significantly improved the efficacy of tumor repression without increasing side effects, which were due to highly specific tumor-targeting drug delivery system and synergistic anticancer effects by co-inactivation of AKT and Src in HNSCC cells. Conclusions Addition of AKT blockade improves anti-HNSCC efficacy of anti-Src therapy, and co-delivery of capivasertib and saracatinib by tumor-targeting NPs has the potential to achieve better treatment outcomes than the free drug combination.

Background Metastatic lung cancer is a life-threatening condition that develops when cancer in another area of the body metastasizes, or spreads, to the lung. Despite advances in our understanding of primary lung oncogenesis, the biological basis driving the progression from primary to metastatic lung cancer remains poorly characterized. Methods Genetic knockdown of the particular genes in cancer cells were achieved by lentiviral-mediated interference. Invasion potential was determined by Matrigel and three-dimensional invasion. The secretion of matrix metalloproteinase 2 (MMP2) and MMP9 were measured by ELISA. Protein levels were assessed by Western blotting and immunohistochemistry. Protein-protein interactions were determined by immunoprecipitation. An experimental mouse model was generated to investigate the gene regulation in tumor growth and metastasis. Results Nck-associated protein 1 (NAP1/NCKAP1) is highly expressed in primary non-small-cell lung cancer (NSCLC) when compared with adjacent normal lung tissues, and its expression levels are strongly associated with the histologic tumor grade, metastasis and poor survival rate of NSCLC patients. Overexpression of NAP1 in lowly invasive NSCLC cells enhances MMP9 secretion and invasion potential, whereas NAP1 silencing in highly invasive NSCLC cells produces opposing effects in comparison. Mechanistic studies further reveal that the binding of NAP1 to the cellular chaperone heat shock protein 90 (HSP90) is required for its protein stabilization, and NAP1 plays an essential role in HSP90-mediated invasion and metastasis by provoking MMP9 activation and the epithelial-to-mesenchymal transition in NSCLC cells. Conclusions Our insights demonstrate the importance and functional regulation of the HSP90-NAP1 protein complex in cancer metastatic signaling, which spur new avenues to target this interaction as a novel approach to block NSCLC metastasis. Electronic supplementary material The online version of this article (10.1186/s13046-019-1124-0) contains supplementary material, which is available to authorized users.

Background A promising arsenal of histone deacetylase (HDAC)-targeted treatment has emerged in the past decade, as the abnormal targeting or retention of HDACs to DNA regulatory regions often occurs in many cancers. Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive malignancies worldwide associated with poor overall survival in late-stage patients. HDAC inhibitors have great potential to treat this devastating disease; however, few has been studied regarding the beneficial role of HDAC inhibition in anti-HNSCC therapy and the underlying molecular mechanisms remain elusive. Methods Cell migration and invasion were examined by wound closure and Transwell assays. Protein levels and interactions were assessed by Western blotting and immunoprecipitation. HDAC activity was measured with the fluorometric HDAC Activity Assay. Phospho-receptor tyrosine kinase (RTK) profiling was determined by the Proteome Profiler Human Phospho-RTK Array. Results ADP-ribosylation factor 1 (Arf1), a small GTPase coordinating vesicle-mediated intracellular trafficking, can be inactivated by HDAC inhibitors through histone acetylation-independent degradation of epidermal growth factor receptor (EGFR) in HNSCC cells. Mechanistically, high levels of Arf1 activity are maintained by binding to phosphorylated EGFR which is localized on HNSCC cell plasma membrane. Decreased EGFR phosphorylation is associated with reduced EGFR protein levels in the presence of TSA, which inactivates Arf1 and eventually inhibits invasion in HNSCC cells. Conclusions Our insights explore the critical role of EGFR-Arf1 complex in driving HNSCC progression, and demonstrate the selective action of HDAC inhibitors on this specific axis for suppressing HNSCC invasion. This novel finding represents the first example of modulating the EGFR-Arf1 complex in HNSCC by small molecule agents. Electronic supplementary material The online version of this article (10.1186/s13046-019-1080-8) contains supplementary material, which is available to authorized users.

Cisplatin is well-known for its damaging effect on nuclear DNA, leading to cell death due to blockage of DNA replication and transcription, but this activity cannot fully explain why cisplatin displays cytotoxicity in post-mitotic tissues, suggesting other mechanisms may be in play. Many studies have challenged the current model of cisplatin resistance, however, the precise mechanism behind is still unknown. Here, we report that the mitochondrial protein ATAD3A functions as an oncogene in oral squamous cell carcinoma (OSCC), promoting cell proliferation and enhancing the ability of colony formation and anchorage-independent growth. Moreover, ATAD3A is involved in cisplatin resistance in OSCC, and knockdown of ATAD3A enhanced the sensitivity of OSCC cells to cisplatin. It appears that ATAD3A-mediated cisplatin resistance is regulated by other mechanisms rather than its expression levels, as evidenced by overexpression of a Walker A (WA) dead mutant of ATAD3A leads to a suppression in OSCC cell growth and resensitizes cisplatin-resistant OSCC cells to this drug, indicating a potent dominant-negative effect of defective ATP-binding of ATAD3A in chemotherapy. Our study demonstrates for the first time that ATAD3A plays an oncogenic role in OSCC and abrogating its ATP-binding ability may represent a promising regimen for better treatment of patients with OSCC, especially for those who suffer from cisplatin-resistance. Citation Format: Liwei Lang, Leslie Duncan, Caleb Jensen, Chloe Shay, Yong Teng. The mitochondrial protein ATAD3A promotes cisplatin resistance in oral squamous cell carcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-130.

Histone deacetylase (HDAC)-targeted treatment has the great potential to treat head and neck squamous cell carcinoma (HNSCC). However, little has been reported regarding the beneficial role of HDAC inhibition in anti-HNSCC therapy and the underlying molecular mechanisms remain elusive. Here, we demonstrate that ADP-ribosylation factor 1 (Arf1), a small GTPase coordinating vesicle-mediated intracellular trafficking, can be inactivated by HDAC inhibitors TSA and PXD101, through histone acetylation-independent degradation of epidermal growth factor receptor (EGFR) in HNSCC cells. Mechanistically, activated Arf1 (GTP-Arf1) is maintained by binding to phosphorylated EGFR on the cancer cell plasma membrane. Decreased EGFR phosphorylation is associated with reduced EGFR protein levels in the presence of HDAC inhibitors, which inactivates Arf1 and eventually inhibits its dependent invasion in HNSCC cells. This novel finding represents the first example of modulating the EGFR-Arf1 complex in HNSCC by small-molecule agents. Our insights not only explore the critical role of the EGFR-Arf1 complex in driving HNSCC progression, but also shed light onto the molecular events accounting for HDAC-targeted therapy. Citation Format: Leilei He, Lixia Gao, Liwei Lang, Chloe Shay, Yong Teng. Inactivating the EGFR-Arf1 axis by HDAC-targeted therapy to suppress invasiveness of head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B09.

Background Inhibition of metastasis of head and neck squamous cell carcinoma (HNSCC) is one of the most important challenges in cancer treatment. Src, a non-receptor tyrosine kinase, has been implicated as a key promoter in tumor progression and metastasis of HNSCC. However, Src therapy for HNSCC is limited by lack of efficient in vivo delivery and underlying mechanisms remain elusive. Methods Src knockdown cells were achieved by lentiviral-mediated interference. Cell migration and invasion were examined by wound healing and Transwell assays. Protein levels were determined by Western blot and/or immunohistochemistry. The Src inhibitor saracatinib was loaded into self-assembling nanoparticles by the solvent evaporation method. An experimental metastasis mouse model was generated to investigate the drug efficacy in metastasis. Results Blockade of Src kinase activity by saracatinib effectively suppressed invasion and metastasis of HNSCC. Mechanistic assessment of the drug effects in HNSCC cells showed that saracatinib induced suppression of Src-dependent invasion/metastasis through downregulating the expression levels of Vimentin and Snail proteins. In tests in mice, saracatinib loaded into the novel multifunctional nanoparticles exhibited superior effects on suppression of HNSCC metastasis compared with the free drug, which is mainly attributed to highly specific and efficient tumor-targeted drug delivery system. Conclusions These findings and advances are of great importance to the development of Src-targeted nanomedicine as a more effective therapy for metastatic HNSCC. Electronic supplementary material The online version of this article (10.1186/s13045-018-0623-3) contains supplementary material, which is available to authorized users.

The tumor microenvironment induces endoplasmic reticulum (ER) stress in tumor cells, an event that can promote progression, but it is unknown how tumor cells adapt to this stress. In this study, we show that the fibroblast growth factor FGF19, a gene frequently amplified in hepatocellular carcinoma (HCC), facilitates a survival response to ER stress. Levels of FGF19 expression were increased in stressed HCC cells in culture and in a mouse xenograft model. Induction of ER stress required the transcription factor ATF4, which directly bound the FGF19 promoter. In cells where ER stress was induced, FGF19 overexpression promoted HCC cell survival and increased resistance to apoptosis, whereas FGF19 silencing counteracted these effects. Mechanistic investigations implicated glycogen synthase kinase-3β (GSK3β) in regulating nuclear accumulation of the stress-regulated transcription factor Nrf2 activated by FGF19. Our findings show how FGF19 provides a cytoprotective role against ER stress by activating a FGFR4–GSK3β–Nrf2 signaling cascade, with implications for targeting this signaling node as a candidate therapeutic regimen for HCC management. Cancer Res; 77(22); 6215–25. ©2017 AACR.

Background Although major improvements have been made in surgical management, chemotherapeutic, and radiotherapeutic of prostate cancer, many prostate cancers remain refractory to treatment with standard agents. Therefore, the identification of new molecular targets in cancer progression and development of novel therapeutic strategies to target them are very necessary for achieving better survival for patients with prostate cancer. Activation of small GTPases such as Ras and Arf1 is a critical component of the signaling pathways for most of the receptors shown to be upregulated in advanced prostate cancer. Methods The drug effects on cell proliferation were measured by CellTiter 96® AQueous One Solution Cell Proliferation Assay. The drug effects on cell migration and invasion were determined by Radius™ 24-well and Matrigel-coated Boyden chambers. The drug effects on apoptosis were assessed by FITC Annexin V Apoptosis Detection Kit with 7-AAD and Western blot with antibodies against cleaved PARP and Caspase 3. A NOD/SCID mouse model generated by subcutaneous injection was used to assess the in vivo drug efficacy in tumor growth. ERK activation and tumor cell proliferation in xenografts were examined by immunohistochemistry. Results We show that Exo2, a small-molecule inhibitor that reduces Arf1 activation, effectively suppresses prostate cancer cell proliferation by blocking ERK1/2 activation. Exo2 also has other effects, inhibiting migration and invasion of PCa cells and inducing apoptosis. The Ras inhibitor salirasib augments Exo2-induced cytotoxicity in prostate cancer cells partially by enhancing the suppression of ERK1/2 phosphorylation. In a xenograft mouse model of prostate cancer, Exo2 reduces prostate tumor burden and inhibits ERK1/2 activation at a dose of 20 mg/kg. Synergistic treatment of salirasib and Exo2 exhibits a superior inhibitory effect on prostate tumor growth compared with either drug alone, which may be attributed to the more efficient inhibition of ERK1/2 phosphorylation. Conclusion This study suggests that simultaneous blockade of Arf1 and Ras activation in prostate cancer cells is a potential targeted therapeutic strategy for preventing prostate cancer development. Electronic supplementary material The online version of this article (doi:10.1186/s13046-017-0583-4) contains supplementary material, which is available to authorized users.

Head and neck cancer (HNC) exhibiting resistance to molecular-targeted therapeutics poses a challenge to their effective clinical management and alternative treatment strategies are actively sought to improve results. Src is commonly hyperactivated in HNC cells and has been implicated as an oncogenic driver in the development and progression of HNC. Unfortunately, the clinical benefit is dampened significantly in HNC patients because only a small fraction of patients respond positively to Src-targeted treatment, and many develop drug resistance. Here, we demonstrate that the addition of AKT blockade in Src-targeted treatment may prevent activation of alternative signaling pathways to bypass the Src inhibition in HNC cells. The combination of Src and AKT inhibitors significantly suppressed HNC growth more efficiently than either drug alone. However, the properties and pharmacokinetics of two inhibitors required a novel approach to optimal delivery into the same tumor cells. To address this, we developed novel tumor-targeting nanoparticles to selectively co-deliver Src and AKT inhibitors to the tumor site in an orthotopic mouse model of HNC. This nanotherapeutic modality significantly improved the efficacy of tumor repression, which was mainly attributed to the highly specific tumor-targeted drug delivery system and synergistic anticancer effect by co-inactivation of AKT and Src. The results of this study will enable us to take a major step toward addressing the urgent need for single drug resistance and failure, and strongly impact on the development of clinically acceptable therapeutics to combat HNC. Citation Format: Liwei Lang, Chloe Shay, Xuli Wang, Yong Teng. Co-delivery nanoparticle to overcome therapeutic resistance in human head and neck cancer promoted by insufficient Src-targeted treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2114.

The fibroblast growth factor 19 gene FGF19 has been reported to be amplified in several cancer types and encodes for a key autocrine signaler known to promote tumorigenic growth. Thus, it is imperative to understand which cancers are oncogenically addicted to FGF19 amplification as well as the role it serves in these cancer types. We report for the first time that high FGF19 amplification in head and neck squamous cell carcinomas (HNSCC) is associated with increased autocrine secretion of FGF19 and poor patient outcome in HNSCC. FGF19 amplification corresponded with constitutive activation of FGFR4-dependent ERK/AKT-p70S6K-S6 signaling, and addition of human recombinant FGF19 could promote proliferation and soft agar colony formation in HNSCC cells with low FGF19 expression through activating FGFR4 and downstream signaling cascades. Consistently, FGF19 knockout counteracted the observed effects in HNSCC cells carrying high endogenous FGF19, and significantly suppressed tumor growth in an orthotopic mouse model of HNSCC. This study demonstrates that FGF19 gene amplification corresponds with an increased dependency upon FGF19/FGFR4 autocrine signaling in HNSCC, revealing a therapeutic target for this cancer type. Note: This abstract was not presented at the meeting. Citation Format: Liwei Lang, Lixia Gao, Chloe Shay, Xiangdong Zhao, Austin Shull, Yong Teng. Essential role of autocrine FGF19-FGFR4 signaling in head and neck tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 853.