Targeting SMYD2 promotes ferroptosis and impacts the progression of pancreatic cancer through the c-Myc/NCOA4 axis-mediated ferritinophagy.

BACKGROUND: Pancreatic cancer (PC) is characterized by a poor prognosis and limited treatment options. Ferroptosis plays an important role in cancer, SET and MYND domain-containing protein 2 (SMYD2) is widely expressed in various cancers. However, the role of SMYD2 in regulating ferroptosis in PC remains unexplored. This study aimed to investigate the role of SMYD2 in mediating ferroptosis and its mechanistic implications in PC progression. METHODS: The levels of SMYD2, c-Myc, and NCOA4 were assessed in PC tissues, and peritumoral tissues. SMYD2 expression was further analyzed in human PC cell lines. In BxPC3 cells, the expression of c-Myc, NCOA4, autophagy-related proteins, and mitochondrial morphology, was evaluated following transfection with si-SMYD2 and treatment with autophagy inhibitors and ferroptosis inhibitors. Ferroptosis levels were quantified using flow cytometry and ELISA assays. RNA immunoprecipitation was conducted to elucidate the interaction between c-Myc and NCOA4 mRNA. A xenograft mouse model was constructed to validate the impact of SMYD2 knockdown on PC growth. RESULTS: SMYD2 and c-Myc were found to be highly expressed in PC tissues, while NCOA4 showed reduced expression. Among the PC cell lines studied, BxPC3 cells exhibited the highest SMYD2 expression. SMYD2 knockdown led to decreased c-Myc levels, increased NCOA4 expression, reduced autophagy-related protein expression, mitochondrial shrinkage, and heightened ferroptosis levels. Additionally, an interaction between c-Myc and NCOA4 was identified. In vivo, SMYD2 knockdown inhibited tumor growth. CONCLUSIONS: Targeting SMYD2 inhibits PC progression by promoting ferritinophagy-dependent ferroptosis through the c-Myc/NCOA4 axis. These findings provide insights into potential diagnostic and therapeutic strategies for PC.

NCAPD2 augments the tumorigenesis and progression of human liver cancer via the PI3K­Akt­mTOR signaling pathway.

Non­SMC condensin I complex subunit D2 (NCAPD2) is a newly identified oncogene; however, the specific biological function and molecular mechanism of NCAPD2 in liver cancer progression remain unknown. In the present study, the aberrant expression of NCAPD2 in liver cancer was investigated using public tumor databases, including TNMplot, The Cancer Genome Atlas and the International Cancer Genome Consortium based on bioinformatics analyses, and it was validated using a clinical cohort. It was revealed that NCAPD2 was significantly upregulated in liver cancer tissues compared with in control liver tissues, and NCAPD2 served as an independent prognostic factor and predicted poor prognosis in liver cancer. In addition, the expression of NCAPD2 was positively correlated with the percentage of Ki67+ cells. Finally, single­cell sequencing data, gene­set enrichment analyses and in vitro investigations, including cell proliferation assay, Transwell assay, wound healing assay, cell cycle experiments, cell apoptosis assay and western blotting, were carried out in human liver cancer cell lines to assess the biological mechanisms of NCAPD2 in patients with liver cancer. The results revealed that the upregulation of NCAPD2 enhanced tumor cell proliferation, invasion and cell cycle progression at the G2/M­phase transition, and inhibited apoptosis in liver cancer cells. Furthermore, NCAPD2 overexpression was closely associated with the phosphatidylinositol 3­kinase (PI3K)­Akt­mammalian target of rapamycin (mTOR)/c­Myc signaling pathway and epithelial­mesenchymal transition (EMT) progression in HepG2 and Huh7 cells. In addition, upregulated NCAPD2 was shown to have adverse effects on overall survival and disease­specific survival in liver cancer. In conclusion, the overexpression of NCAPD2 was shown to lead to cell cycle progression at the G2/M­phase transition, activation of the PI3K­Akt­mTOR/c­Myc signaling pathway and EMT progression in human liver cancer cells.

Development of a fluorescent ligand that specifically binds to the c-MYC G-quadruplex by migrating the benzene group on a carbazole-benzothiazolium scaffold.

c-MYC is one of the most important oncogenes, which is overexpressed in many cancers, and is highly related to development, metastasis, and drug resistance of cancers. The G4 structure in the promoter of c-MYC oncogene contributes a lot to the gene transcriptional mechanism. Small-molecule ligands binding to the c-MYC G4 appear to be a new class of anticancer agents. However, selective ligands for the c-MYC G4 over other G4s have been rarely reported. In this study, we reported a novel fluorescent ligand by migrating the benzene group on a carbazole-benzothiazolium scaffold, which was demonstrated to exhibit considerable specificity to the c-MYC G4, which was distinguished from other small-molecule ligands. The further cellular experiments suggested that this ligand may indeed target the promoter G4 and cause apparent transcriptional inhibition of the c-MYC oncogene instead of other G4-mediated oncogenes, which thereby resulted in cancer cell growth inhibition. Collectively, this study provided a good example for developing specific c-MYC G4 ligands, which may further develop into an effective anticancer agent that inhibit the c-MYC expression.

Topical application of phenformin ameliorates the psoriasis-like inflammatory response via the inhibition of c-Myc expression in keratinocytes.

BACKGROUND: Psoriasis is a chronic inflammatory skin disease characterized by a complex pathogenesis involving various types of cells and cytokines. Among those, the pro-inflammatory cytokine IL-23/IL-17A axis plays a crucial role in the development and rapid progression of psoriasis. Phenformin, a derivative of metformin and a member of the biguanide class of drugs, exhibits superior anti-inflammatory and anti-tumor efficacy compared to metformin. However, the potential role of phenformin in anti-psoriatic skin inflammation has not been explored. METHODS: In this study, we utilized a mouse model of psoriasis and an in vitro model using human keratinocytes to investigate whether phenformin can suppress psoriasis-like inflammatory responses. RESULTS: Our results demonstrate that the topical application of phenformin significantly inhibited acute skin inflammatory responses in the psoriasis mouse model induced by imiquimod (IMQ). Additionally, phenformin suppressed the expression of psoriasis-related cytokines IL-17, IL-23, IL-8, and S100A8/S100A9 in an in vitro psoriatic keratinocyte model induced by IMQ. Furthermore, we found that IMQ-induced psoriatic skin and IMQ-treated keratinocytes exhibited high expression of the c-Myc gene, which was downregulated by phenformin. The c-Myc inhibitor JQ1 similarly inhibited the psoriatic inflammatory response and the expression of psoriasis-related cytokines in both in vitro and in vivo models. CONCLUSION: phenformin ameliorates the psoriasis-like inflammatory response by inhibiting c-Myc expression in keratinocytes, suggesting its potential as a topical drug for the treatment of psoriasis.

SOX2 represses c-MYC transcription by altering the co-activator landscape of the c-MYC super-enhancer and promoter regions.

Our previous studies determined that elevating SOX2 in a wide range of tumor cells leads to a reversible state of tumor growth arrest. Efforts to understand how tumor cell growth is inhibited led to the discovery of a SOX2:MYC axis that is responsible for downregulating c-MYC (MYC) when SOX2 is elevated. Although we had determined that elevating SOX2 downregulates MYC transcription, the mechanism responsible was not determined. Given the challenges of targeting MYC clinically, we set out to identify how elevating SOX2 downregulates MYC transcription. In this study, we focused on the MYC promoter region and an upstream region of the MYC locus that contains a MYC super-enhancer encompassing five MYC enhancers and which is associated with several cancers. Here we report that BRD4 and p300 associate with each of the MYC enhancers in the upstream MYC super-enhancer as well as the MYC promoter region and that elevating SOX2 decreases the recruitment of BRD4 and p300 to these sites. Additionally, we determined that elevating SOX2 leads to increases in the association of SOX2 and H3K27me3 within the MYC super-enhancer and the promoter region of MYC. Importantly, we conclude that the increases in SOX2 within the MYC super-enhancer precipitate a cascade of events that culminates in the repression of MYC transcription. Together, our studies identify a novel molecular mechanism able to regulate MYC transcription in two distinctly different tumor types and provide new mechanistic insights into the molecular interrelationships between two master regulators, SOX2 and MYC, widely involved in multiple cancers.

Tumor-intrinsic CDC42BPB confers resistance to anti-PD-1 immune checkpoint blockade in breast cancer.

Immune checkpoint blockade has been used to treat breast cancer, but the clinical responses remain relatively poor. We have used the CRISPR-Cas9 kinome knockout library consisting of 763 kinase genes to identify tumor-intrinsic kinases conferring resistance to anti-PD-1 immune checkpoint blockade. We have identified the CDC42BPB kinase as a potential target to overcome the resistance to anti-PD-1 immune checkpoint blockade immunotherapy. We found that CDC42BPB is highly expressed in breast cancer patients who are non-responsive to immunotherapy. Furthermore, a small-molecule pharmacological inhibitor, BDP5290, which targets CDC42BPB, synergized with anti-PD-1 and enhanced tumor cell killing by promoting T cell proliferation in both in vitro and in vivo assays. Moreover, anti-PD-1-resistant breast cancer cells showed higher expression of CDC42BPB, and its inhibition rendered the resistant cells more susceptible to T cell killing in the presence of anti-PD-1. We also found that CDC42BPB phosphorylated AURKA, which in turn upregulated PD-L1 through cMYC. Our results have revealed a robust link between tumor-intrinsic kinase and immunotherapy resistance and have provided a rationale for a unique combination therapy of CDC42BPB inhibition and anti-PD-1 immunotherapy for breast cancer.

Ribosome stalling during c-myc translation presents actionable cancer cell vulnerability.

Myc is a major driver of tumor initiation, progression, and maintenance. Up-regulation of Myc protein level rather than acquisition of neomorphic properties appears to underlie most Myc-driven cancers. Cellular mechanisms governing Myc expression remain incompletely defined. In this study, we show that ribosome-associated quality control (RQC) plays a critical role in maintaining Myc protein level. Ribosomes stall during the synthesis of the N-terminal portion of cMyc, generating aberrant cMyc species and necessitating deployment of the early RQC factor ZNF598 to handle translational stress and restore cMyc translation. ZNF598 expression is up-regulated in human glioblastoma (GBM), and its expression positively correlates with that of cMyc. ZNF598 knockdown inhibits human GBM neurosphere formation in cell culture and Myc-dependent tumor growth in vivo in Drosophila. Intriguingly, the SARS-COV-2-encoded translational regulator Nsp1 impinges on ZNF598 to restrain cMyc translation and consequently cMyc-dependent cancer growth. Remarkably, Nsp1 exhibits synthetic toxicity with the translation and RQC-related factor ATP-binding cassette subfamily E member 1, which, despite its normally positive correlation with cMyc in cancer cells, is co-opted by Nsp1 to down-regulate cMyc and inhibit tumor growth. Ribosome stalling during c-myc translation thus offers actionable cancer cell vulnerability.

c-Myc-XRCC2-FOS axis promotes the proliferation and the resistance to Doxorubicin of NSCLC.

Lung cancer represents one of the most prevalent malignant neoplasms, commanding an alarming incidence and mortality rate globally. Non-small cell lung cancer (NSCLC), constituting approximately 80 %-90 % of all lung cancer cases, is the predominant pathological manifestation of this disease, with a disconcerting 5-year survival rate scarcely reaching 10 %. Extensive prior investigations have elucidated that the aberrant expression of X-ray repair cross-complementing gene 2 (XRCC2), a critical meiotic gene intricately involved in the DNA damage repair process, is intimately associated with tumorigenesis. Nevertheless, the precise roles and underlying mechanistic pathways of XRCC2 in NSCLC remain largely elusive. In the present study, we discerned an overexpression of XRCC2 within NSCLC patient tissues, particularly in high-grade samples, when juxtaposed with normal tissues. Targeted knockdown of XRCC2 notably impeded the proliferation of NSCLC both in vitro and in vivo. Comprehensive RNA sequencing and flow rescue assays unveiled that XRCC2 augments the proliferation of NSCLC cells through the down-regulation of FOS expression. Moreover, the c-Myc gene was definitively identified as an XRCC2 transcriptional factor by means of chromatin immunoprecipitation (ChIP) and luciferase reporter assays, whereby pharmacological attenuation of c-Myc expression, in conjunction with Doxorubicin, synergistically curtailed NSCLC cell growth both in vitro and in vivo. Collectively, our findings proffer critical insights into the novel c-Myc-XRCC2-FOS axis in promoting both proliferation and resistance to Doxorubicin in NSCLC cells, thereby extending a promising avenue for potential new diagnostic strategies and therapeutic interventions in NSCLC.

Integrative clinical and preclinical studies identify FerroTerminator1 as a potent therapeutic drug for MASH.

The complex etiological factors associated with metabolic dysfunction-associated fatty liver disease (MAFLD), including perturbed iron homeostasis, and the unclear nature by which they contribute to disease progression have resulted in a limited number of effective therapeutic interventions. Here, we report that patients with metabolic dysfunction-associated steatohepatitis (MASH), a pathological subtype of MAFLD, exhibit excess hepatic iron and that it has a strong positive correlation with disease progression. FerroTerminator1 (FOT1) effectively reverses liver injury across multiple MASH models without notable toxic side effects compared with clinically approved iron chelators. Mechanistically, our multi-omics analyses reveal that FOT1 concurrently inhibits hepatic iron accumulation and c-Myc-Acsl4-triggered ferroptosis in various MASH models. Furthermore, MAFLD cohort studies suggest that serum ferritin levels might serve as a predictive biomarker for FOT1-based therapy in MASH. These findings provide compelling evidence to support FOT1 as a promising novel therapeutic option for all stages of MAFLD and for future clinical trials.

Ferulic acid inhibits tumor proliferation and attenuates inflammation of hepatic tissues in experimentally induced HCC in rats.

Hepatocellular carcinoma (HCC) is a prevalent form of primary liver cancer with a 5-year survival rate of just 18%. Ferulic acid, a natural compound found in fruits and vegetables such as sweet corn, rice bran, and dong quai, is an encouraging drug known for its diverse positive effects on the body, including anti-inflammatory, anti-apoptotic, and neuroprotective properties. Our study aimed to investigate the potential antitumor effects of ferulic acid to inhibit tumor growth and inflammation of HCC in rats. HCC was induced in rats by administering thioacetamide. Additionally, some rats were given 50 mg/kg of ferulic acid three times a week for 16 weeks. Liver function was assessed by measuring serum alpha-fetoprotein (AFP) and examining hepatic tissue sections stained with hematoxylin/eosin or anti-hypoxia induced factor-1α (HIF-1α). The hepatic mRNA and protein levels of HIF-1α, nuclear factor κB (NFκB), tumor necrosis factor-α (TNF-α), mammalian target of rapamycin (mTOR), signal transducer and activator of transcription 3 (STAT3), cMyc, and cyclin D1 were examined. The results showed that ferulic acid increased the rats' survival rate by reducing serum AFP levels and suppressing hepatic nodules. Furthermore, ferulic acid ameliorated the appearance of vacuolated cytoplasm induced by HCC, reduced apoptotic nuclei, and necrotic nodules. Finally, ferulic acid decreased the expression of HIF-1α, NFκB, TNF-α, mTOR, STAT3, cMyc, and cyclin D1. In conclusion, ferulic acid is believed to possess antitumor properties by inhibiting HCC-induced hypoxia through the suppression of HIF-1α expression. Additionally, it helps in reducing the expression of mTOR, STAT3, cMyc, and cyclin D1, thereby slowing down tumor growth. Lastly, ferulic acid reduced hepatic tissue inflammation by downregulating NFκB and TNF-α.

Composite Burkitt Lymphoma and Classical Hodgkin Lymphoma in an Human Immunodeficiency Virus (HIV)-Positive Patient.

Lymphoma, a term encompassing tumor masses in the lymph nodes, is often classified into Hodgkin and non-Hodgkin lymphomas, each with distinct subtypes. We present the unique case of an HIV-positive patient diagnosed with Burkitt lymphoma and classical Hodgkin lymphoma simultaneously as a composite lymphoma. Over the course of five years, a variety of dose-adjusted chemotherapy regimens were used that ultimately proved highly effective. The successful management of this rare case reinforces the significance of considering unexpected combinations of neoplastic processes during diagnosis and treatment planning.

Correlations between C-myc expression, BMI-1 expression, and vaginal microecology with HPV-DNA load in patients with different cervical lesions.

OBJECTIVE: To investigate the correlations between the expressions of proto-oncogenes C-myc and B-cell-specific Moloney leukemia virus integration site-1 (BMI-1), vaginal microecology, and human papillomavirus-DNA (HPV-DNA) load in patients with different cervical lesions. METHODS: A total of 51 patients with cervix squamous cell carcinoma (CSCC), 72 patients with cervical intraepithelial neoplasia (CIN) and 50 patients with normal cervix (NC) who were diagnosed or admitted between Jan. 1st 2020 and Dec. 31st 2022 at the Suzhou Hospital of Integrated Traditional Chinese and Western Medicine were selected and divided into three groups, i.e., the CSCC group, the CIN group and the NC group, for a retrospective analysis. Hybrid capture 2 (hc2) was used to detect the HPV-DNA load in each group. Immunohistochemistry was performed to detect C-myc and BMI-1 expressions in each group. The indicators of vaginal microecology in patients were compared among groups to analyze the correlations between C-myc, BMI-1 expressions, vaginal microecology and HPV-DNA load. RESULTS: The HPV-DNA load and expression levels of positive C-myc and BMI-1 in the CSCC group were all higher than those of the CIN and NC groups (P<0.05). The detection rate of lactobacillus in the CSCC group was lower than that of the CIN and NC groups. The percentages of leukocyte esterase (LE) positivity and pH ≥4.6 were higher in the CSCC group than those in the CIN and NC groups (P<0.05). The difference in the detection rate of spores among the three groups was not significant (P>0.05). Both C-myc and BMI-1 scores were positively correlated with HPV-DNA load in the 173 samples. CONCLUSION: The proto-oncogenes C-myc and BMI-1 were highly expressed in the cervical tissues of CIN and CSCC patients, whose vaginal microecology was also altered. Both may play an important role in the progression of cervical lesions.

The roles of FGFR3 and c-MYC in urothelial bladder cancer.

Bladder cancer is one of the most frequently occurring cancers worldwide. At diagnosis, 75% of urothelial bladder cancer cases have non-muscle invasive bladder cancer while 25% have muscle invasive or metastatic disease. Aberrantly activated fibroblast growth factor receptor (FGFR)-3 has been implicated in the pathogenesis of bladder cancer. Activating mutations of FGFR3 are observed in around 70% of NMIBC cases and ~ 15% of MIBCs. Activated FGFR3 leads to ligand-independent receptor dimerization and activation of downstream signaling pathways that promote cell proliferation and survival. FGFR3 is an important therapeutic target in bladder cancer, and clinical studies have shown the benefit of FGFR inhibitors in a subset of bladder cancer patients. c-MYC is a well-known major driver of carcinogenesis and is one of the most commonly deregulated oncogenes identified in human cancers. Studies have shown that the antitumor effects of FGFR inhibition in FGFR3 dependent bladder cancer cells and other FGFR dependent cancers may be mediated through c-MYC, a key downstream effector of activated FGFR that is involved tumorigenesis. This review will summarize the current general understanding of FGFR signaling and MYC alterations in cancer, and the role of FGFR3 and MYC dysregulation in the pathogenesis of urothelial bladder cancer with the possible therapeutic implications.

Bufalin: A promising therapeutic drug against the cisplatin-resistance of ovarian cancer by targeting the USP36/c-Myc axis.

Cisplatin (DPP) resistance is a severe obstacle to ovarian cancer (OC) treatment. Our research aims to uncover the therapeutic effect and the underlying mechanism of Bufalin against DDP resistance. The cell viability, proliferation capacity, γH2AX expression, and apoptosis ratio were quantified via CCK8 assay, colony formation assay, immunofluorescence, and flow cytometry analysis respectively. Xenografting experiment was performed to detect the tumor growth. Molecular docking was applied to mimic the combination of Bufalin and USP36 protein, and Western blotting was conducted to measure the Bax, Bcl-2, γH2AX, USP36, and c-Myc expression. The c-Myc ubiquitination and half-life were detected via ubiquitination assay and cycloheximide chasing assay. Bufalin treatment notably suppressed the cell viability and colony numbers, and increased the apoptosis ratio and γH2AX level in the DDP treatment group. Bufalin therapy also notably inhibited tumor growth, Bax, Bcl-2, and γH2AX expression in vivo. Moreover, the Bufalin application remarkedly reduced the c-Myc expression and half-life and increased the c-Myc ubiquitination via interaction and subsequent down-regulation of USP36. Knockdown of USP36 reversed the antiproliferative effect and proapoptotic capacity of Bufalin therapy in the DDP treatment group. In conclusion, Bufalin can overcome the DDP resistance in vitro and in vivo via the USP36/c-Myc axis, which innovatively suggests the therapeutic potential of Bufalin against DDP resistance ovarian cancer.

ZNF300 promotes proliferation and migration of hepatocellular carcinoma by upregulating c-MYC gene expression.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. Currently, the treatments of HCC are limited to surgical resection and liver transplantation, and there is no effective systemic therapy. OBJECTIVES: To investigate the regulatory mechanism of zinc finger protein 300 (ZNF300) in hepatocellular carcinoma (HCC). METHODS: The expressions of ZNF300 in HCC tissue samples and HCC cell lines (Hep3B, Huh7, SNU-387) were detected. ZNF300 overexpression vector (ZNF300) or shRNAZNF300 (shZNF300) was transfected into HCC cells to increase or inhibit ZNF300 expression. 5-Ethynyl-2'-deoxyuridine assay (EdU), cell counting kit-8 assay (CCK-8) and transwell invasion assay were conducted to evaluate the proliferation, viability, migration, and invasion of HCC cells respectively. The expressions of tumor migration and invasion related proteins (matrix metallopeptidase 2 (MMP-2) and MMP-9), c-MYC, and MAPK/ERK signaling pathway related molecules (p-ERK1/2, ERK1/2, p-P38, P38) were determined by western blotting. Hep3B cells transfected with shZNF300 were subcutaneously injected into nude mice to perform tumor xenograft experiment. Tumor volume and weight were measured. RESULTS: ZNF300 was upregulated in HCC tissues and cells. The expressions of MMP-2 and MMP-9 were increased in HCC cells after transfecting with ZNF300 but reduced in HCC cells transfected with shZNF300. Downregulation of ZNF300 inhibited HCC cell proliferation, migration, and invasion, while overexpression of ZNF300 showed the opposite effects. Moreover, the expressions of c-MYC and MAPK/ERK signaling pathway related molecules were increased after overexpression of ZNF300 but reduced after downregulating ZNF300. In tumor xenograft experiment, downregulation of ZNF300 reduced tumor volume and weight. CONCLUSION: The present study proved that downregulation of ZNF300 inhibited HCC growth by reducing c-MYC expression and MAPK/ERK signaling pathway.

Circular RNA hsa_circ_0000467 promotes colorectal cancer progression by promoting eIF4A3-mediated c-Myc translation.

BACKGROUND: Colorectal cancer (CRC) is the second most common malignant tumor worldwide, and its incidence rate increases annually. Early diagnosis and treatment are crucial for improving the prognosis of patients with colorectal cancer. Circular RNAs are noncoding RNAs with a closed-loop structure that play a significant role in tumor development. However, the role of circular RNAs in CRC is poorly understood. METHODS: The circular RNA hsa_circ_0000467 was screened in CRC circRNA microarrays using a bioinformatics analysis, and the expression of hsa_circ_0000467 in CRC tissues was determined by in situ hybridization. The associations between the expression level of hsa_circ_0000467 and the clinical characteristics of CRC patients were evaluated. Then, the role of hsa_circ_0000467 in CRC growth and metastasis was assessed by CCK8 assay, EdU assay, plate colony formation assay, wound healing assay, and Transwell assay in vitro and in a mouse model of CRC in vivo. Proteomic analysis and western blotting were performed to investigate the effect of hsa_circ_0000467 on c-Myc signaling. Polysome profiling, RT‒qPCR and dual-luciferase reporter assays were performed to determine the effect of hsa_circ_0000467 on c-Myc translation. RNA pull-down, RNA immunoprecipitation (RIP) and immunofluorescence staining were performed to assess the effect of hsa_circ_0000467 on eIF4A3 distribution. RESULTS: In this study, we found that the circular RNA hsa_circ_0000467 is highly expressed in colorectal cancer and is significantly correlated with poor prognosis in CRC patients. In vitro and in vivo experiments revealed that hsa_circ_0000467 promotes the growth and metastasis of colorectal cancer cells. Mechanistically, hsa_circ_0000467 binds eIF4A3 to suppress its nuclear translocation. In addition, it can also act as a scaffold molecule that binds eIF4A3 and c-Myc mRNA to form complexes in the cytoplasm, thereby promoting the translation of c-Myc. In turn, c-Myc upregulates its downstream targets, including the cell cycle-related factors cyclin D2 and CDK4 and the tight junction-related factor ZEB1, and downregulates E-cadherin, which ultimately promotes the growth and metastasis of CRC. CONCLUSIONS: Our findings revealed that hsa_circRNA_0000467 plays a role in the progression of CRC by promoting eIF4A3-mediated c-Myc translation. This study provides a theoretical basis and molecular target for the diagnosis and treatment of CRC.

USP11 promotes prostate cancer progression by up-regulating AR and c-Myc activity.

Androgen receptor (AR) is a main driver for castration-resistant prostate cancer (CRPC). c-Myc is an oncogene underlying prostate tumorigenesis. Here, we find that the deubiquitinase USP11 targets both AR and c-Myc in prostate cancer (PCa). USP11 expression was up-regulated in metastatic PCa and CRPC. USP11 knockdown (KD) significantly inhibited PCa cell growth. Our RNA-seq studies revealed AR and c-Myc as the top transcription factors altered after USP11 KD. ChIP-seq analysis showed that either USP11 KD or replacement of endogenous USP11 with a catalytic-inactive USP11 mutant significantly decreased chromatin binding by AR and c-Myc. We find that USP11 employs two mechanisms to up-regulate AR and c-Myc levels: namely, deubiquitination of AR and c-Myc proteins to increase their stability and deubiquitination of H2A-K119Ub, a repressive histone mark, on promoters of AR and c-Myc genes to increase their transcription. AR and c-Myc reexpression in USP11-KD PCa cells partly rescued cell growth defects. Thus, our studies reveal a tumor-promoting role for USP11 in aggressive PCa through upregulation of AR and c-Myc activities and support USP11 as a potential target against PCa.

A positive feedback loop between PFKP and c-Myc drives head and neck squamous cell carcinoma progression.

BACKGROUND: The aberrant expression of phosphofructokinase-platelet (PFKP) plays a crucial role in the development of various human cancers by modifying diverse biological functions. However, the precise molecular mechanisms underlying the role of PFKP in head and neck squamous cell carcinoma (HNSCC) are not fully elucidated. METHODS: We assessed the expression levels of PFKP and c-Myc in tumor and adjacent normal tissues from 120 HNSCC patients. A series of in vitro and in vivo experiments were performed to explore the impact of the feedback loop between PFKP and c-Myc on HNSCC progression. Additionally, we explored the therapeutic effects of targeting PFKP and c-Myc in HNSCC using Patient-Derived Organoids (PDO), Cell Line-Derived Xenografts, and Patients-Derived Xenografts. RESULTS: Our findings indicated that PFKP is frequently upregulated in HNSCC tissues and cell lines, correlating with poor prognosis. Our in vitro and in vivo experiments demonstrate that elevated PFKP facilitates cell proliferation, angiogenesis, and metastasis in HNSCC. Mechanistically, PFKP increases the ERK-mediated stability of c-Myc, thereby driving progression of HNSCC. Moreover, c-Myc stimulates PFKP expression at the transcriptional level, thus forming a positive feedback loop between PFKP and c-Myc. Additionally, our multiple models demonstrate that co-targeting PFKP and c-Myc triggers synergistic anti-tumor effects in HNSCC. CONCLUSION: Our study demonstrates the critical role of the PFKP/c-Myc positive feedback loop in driving HNSCC progression and suggests that simultaneously targeting PFKP and c-Myc may be a novel and effective therapeutic strategy for HNSCC.

ROCK1 regulates glycolysis in pancreatic cancer via the c-MYC/PFKFB3 pathway.

BACKGROUND: Dysregulation of Rho-associated coiled coil-containing protein kinases (ROCKs) is involved in the metastasis and progression of various malignant tumors. However, how one of the isomers, ROCK1, regulates glycolysis in tumor cells is incompletely understood. Here, we attempted to elucidate how ROCK1 influences pancreatic cancer (PC) progression by regulating glycolytic activity. METHODS: The biological function of ROCK1 was analyzed in vitro by establishing a silenced cell model. Coimmunoprecipitation confirmed the direct binding between ROCK1 and c-MYC, and a luciferase reporter assay revealed the binding of c-MYC to the promoter of the PFKFB3 gene. These results were verified in animal experiments. RESULTS: ROCK1 was highly expressed in PC tissues and enriched in the cytoplasm, and its high expression was associated with a poor prognosis. Silencing ROCK1 inhibited the proliferation and migration of PC cells and promoted their apoptosis. Mechanistically, ROCK1 directly interacted with c-MYC, promoted its phosphorylation (Ser 62) and suppressed its degradation, thereby increasing the transcription of the key glycolysis regulatory factor PFKFB3, enhancing glycolytic activity and promoting PC growth. Silencing ROCK1 increased gemcitabine (GEM) sensitivity in vivo and in vitro. CONCLUSIONS: ROCK1 promotes glycolytic activity in PC cells and promotes PC tumor growth through the c-MYC/PFKFB3 signaling pathway. ROCK1 knockdown can inhibit PC tumor growth in vivo and increase the GEM sensitivity of PC tumors, providing a crucial clinical therapeutic strategy for PC.

Polyamine and EIF5A hypusination downstream of c-Myc confers targeted therapy resistance in BRAF mutant melanoma.

BACKGROUND: BRAF inhibitors are widely employed in the treatment of melanoma with the BRAF V600E mutation. However, the development of resistance compromises their therapeutic efficacy. Diverse genomic and transcriptomic alterations are found in BRAF inhibitor resistant melanoma, posing a pressing need for convergent, druggable target that reverse therapy resistant tumor with different resistance mechanisms. METHODS: CRISPR-Cas9 screens were performed to identify novel target gene whose inhibition selectively targets A375VR, a BRAF V600E mutant cell line with acquired resistance to vemurafenib. Various in vitro and in vivo assays, including cell competition assay, water soluble tetrazolium (WST) assay, live-dead assay and xenograft assay were performed to confirm synergistic cell death. Liquid Chromatography-Mass Spectrometry analyses quantified polyamine biosynthesis and changes in proteome in vemurafenib resistant melanoma. EIF5A hypusination dependent protein translation and subsequent changes in mitochondrial biogenesis and activity were assayed by O-propargyl-puromycin labeling assay, mitotracker, mitoSOX labeling and seahorse assay. Bioinformatics analyses were used to identify the association of polyamine biosynthesis with BRAF inhibitor resistance and poor prognosis in melanoma patient cohorts. RESULTS: We elucidate the role of polyamine biosynthesis and its regulatory mechanisms in promoting BRAF inhibitor resistance. Leveraging CRISPR-Cas9 screens, we identify AMD1 (S-adenosylmethionine decarboxylase 1), a critical enzyme for polyamine biosynthesis, as a druggable target whose inhibition reduces vemurafenib resistance. Metabolomic and proteomic analyses reveal that polyamine biosynthesis is upregulated in vemurafenib-resistant cancer, resulting in enhanced EIF5A hypusination, translation of mitochondrial proteins and oxidative phosphorylation. We also identify that sustained c-Myc levels in vemurafenib-resistant cancer are responsible for elevated polyamine biosynthesis. Inhibition of polyamine biosynthesis or c-Myc reversed vemurafenib resistance both in vitro cell line models and in vivo in a xenograft model. Polyamine biosynthesis signature is associated with poor prognosis and shorter progression free survival after BRAF/MAPK inhibitor treatment in melanoma cohorts, highlighting the clinical relevance of our findings. CONCLUSIONS: Our findings delineate the molecular mechanisms involving polyamine-EIF5A hypusination-mitochondrial respiration pathway conferring BRAF inhibitor resistance in melanoma. These targets will serve as effective therapeutic targets that can maximize the therapeutic efficacy of existing BRAF inhibitors.