c-Myc Overexpression Promotes Oral Cancer Cell Proliferation and Migration by Enhancing Glutaminase and Glutamine Synthetase Activity

Connecting the dots: investigating the link between environmental, genetic, and epigenetic influences in metabolomic alterations in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) accounts for around 90% of all oral cancers and is the eighth most common cancer worldwide. Despite progress in managing OSCC, the overall prognosis remains poor, with a survival rate of around 50-60%, largely due to tumor size and recurrence. The challenges of late-stage diagnosis and limitations in current methods emphasize the urgent need for less invasive techniques to enable early detection and treatment, crucial for improving outcomes in this aggressive form of oral cancer. Research is currently aimed at unraveling tumor-specific metabolite profiles to identify candidate biomarkers as well as discover underlying pathways involved in the onset and progression of cancer that could be used as new targets for diagnostic and therapeutic purposes. Metabolomics is an advanced technological approach to identify metabolites in different sample types (biological fluids and tissues). Since OSCC promotes metabolic reprogramming influenced by a combination of genetic predisposition and environmental factors, including tobacco and alcohol consumption, and viral infections, the identification of distinct metabolites through screening may aid in the diagnosis of this condition. Moreover, studies have shown the use of metabolites during the catalysis of epigenetic modification, indicating a link between epigenetics and metabolism. In this review, we will focus on the link between environmental, genetic, and epigenetic influences in metabolomic alterations in OSCC. In addition, we will discuss therapeutic targets of tumor metabolism, which may prevent oral tumor growth, metastasis, and drug resistance.

The potential therapeutic targets of glutamine metabolism in head and neck squamous cell carcinoma

Targeting metabolic reprogramming may be an effective strategy to enhance cancer treatment efficacy. Glutamine serves as a vital nutrient for cancer cells. Inhibiting glutamine metabolism has shown promise in preventing tumor growth both in vivo and in vitro through various mechanisms. Therefore, this review collates recent scientific literature concerning the correlation between glutamine metabolism and cancer treatment. Novel treatment modalities based on amino acid transporters, metabolites, and glutaminase are discussed. Moreover, we demonstrate the relationship between glutamine metabolism and tumor proliferation, drug resistance, and the tumor immune microenvironment, offering new perspectives for the clinical treatment of head and neck squamous cell carcinoma, particularly for combined therapies. Identifying innovative approaches for enhancing the efficacy of glutamine-based metabolic therapy is crucial to improving HNSCC treatment.

Network pharmacology integrated molecular docking of fucoidan against oral cancer and in vitro evaluation- A study using GEO datasets

Oral cancer is a widespread health concern in rural India due to a lack of awareness, delayed diagnosis and limited access to affordable treatment options. The current chemotherapy has notable side effects, underscoring the need for new drug candidates with improved bioavailability and specificity. In this current research, fucoidan, a sulphated polysaccharide, was extracted from the brown algae Spatoglossum asperum, and shown to be cytotoxic in vitro against oral cancer cells (KB cell line) at an IC50 of 107.76 µg/ml, suggesting its potential as a drug candidate. This study further aimed to explore the potential therapeutic implications of fucoidan in managing oral cancer using network pharmacology. PharmMapper, Comparative Toxicogenomics Database and SuperPred were initially used to identify fucoidan protein targets. The identified targets were further screened against Gene Expression Omnibus (GSE23558, GSE25099 and GSE146483), OMIM, TCGA and GeneCards datasets to identify oral cancer-specific protein targets. The interactions between the selected proteins were visualised using STRING and Cytoscape. Subsequently, Database for Annotation, Visualization and Integrated Discovery was used for gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of candidate targets. The cancer-related network was assessed using CancerGeneNet, while life expectancy based on the expression of the top 10 CytoHubba ranked hub genes was evaluated using Kaplan-Meier plots. Finally, EGFR, AKT1, HSP90AA1 and SRC were selected for docking and molecular dynamics simulation with fucoidan, using Maestro and GROMACS, respectively.Communicated by Ramaswamy H. Sarma.

Glutaminase (GLS1) gene expression in primary breast cancer

BACKGROUND

Tumor growth is mediated in part by glutamine, and glutaminase is an enzyme necessary for glutamine catabolism. We studied glutaminase (GLS1) gene expression in primary breast cancer to determine correlations with clinical and tumor characteristics, and gene associations in publicly available databases. A better understanding of glutaminase gene expression may help guide further exploration of glutaminase inhibitors in breast cancer.

METHODS

GLS1 mRNA levels were evaluated in The Cancer Genome Atlas (n = 817) and METABRIC (n = 1992) datasets. Associations between GLS1 and tumor subtype (ANOVA followed by post-hoc Tukey test for pairwise comparisons) and selected genes involved in the pathogenesis of breast cancer (Pearson's correlations) were determined in both datasets. In METABRIC, associations with overall survival (Cox proportional hazard model) were determined. For all analyses, p < 0.05 was the threshold for statistical significance.

RESULTS

GLS1 expression was significantly higher in triple negative breast cancer (TNBC) than hormone receptor (HR) +/HER2- and HER2+ breast cancer (p < 0.001) and basal versus luminal A, luminal B, and HER2 enriched breast cancer (p < 0.001) in both datasets. In METABRIC, higher GLS1 expression was associated with improved overall survival (HR 0.91, 95% CI: 0.85-0.97, p = 0.005) and this association remained significant in the TNBC subset (HR 0.83, 95% CI: 0.71-0.98, p = 0.032). GLS1 had significant positive gene correlations with immune, proliferative, and basal genes, and inverse correlations with luminal genes and genes involved in metabolism.

CONCLUSION

GLS1 expression is highest in TNBC and basal breast cancer, supporting ongoing clinical investigation of GLS1 inhibition in TNBC. GLS1 may have prognostic implications but further research is needed to validate this finding. GLS1 had significant positive gene correlations with immune genes, which may have implications for potential combinations of glutaminase inhibition and immunotherapy.

Activated MKK3/MYC crosstalk impairs dabrafenib response in BRAFV600E colorectal cancer leading to resistance

Colorectal cancer (CRC) patients with BRAF mutations develop resistance to BRAF inhibitors at a very early stage. Understanding the molecular mechanisms involved in BRAF inhibitor resistance is critical for the development of novel therapeutic opportunities for this subtype of CRC patients. CRC cells bearing BRAF mutations are mostly sensitive to the abrogation of Mitogen-Activated Protein Kinase Kinase 3 (MKK3), a specific activator of p38MAPKs signaling, suggesting that BRAF alterations might addict CRC cells to the MKK3/p38MAPK signaling. Interestingly, publicly available gene expression profiling data show significantly higher MKK3 transcript levels in CRC lines with acquired resistance to BRAF inhibitors. Herein, we investigated the roles of MKK3 in the response to BRAF targeting (dabrafenib) with COLO205 and HT29 BRAFV600E CRC lines and derived dabrafenib-resistant (DABR) sublines. Dabrafenib treatments reduce MKK3 activation by inducing autophagy in parental but not DABR cells. The MKK3 knockdown induces cell death in DABR cells, whereas ectopic MKK3 expression reduces dabrafenib sensitivity in parental cells. Mechanistically, activated MKK3 interacts and co-localizes with c-Myc oncoprotein (MYC), sustaining MYC protein stability and thus preventing the dabrafenib induced effects in CRC DABR cells both in vitro and in vivo. Overall, we identify a novel molecular mechanism beyond the dabrafenib resistance, shedding light on an uncovered vulnerability for the development of novel therapeutic opportunities in BRAFV600E CRC.

Glutamine metabolism in tumor metastasis: Genes, mechanisms and the therapeutic targets

Cancer cells frequently change their metabolism from aerobic glycolysis to lipid metabolism and amino acid metabolism to adapt to the malignant biological behaviours of infinite proliferation and distant metastasis. The significance of metabolic substances and patterns in tumour cell metastasis is becoming increasingly prominent. Tumour metastasis involves a series of significant steps such as the shedding of cancer cells from a primary tumour, resistance to apoptosis, and colonisation of metastatic sites. However, the role of glutamine in these processes remains unclear. This review summarises the key enzymes and transporters involved in glutamine metabolism that are related to the pathogenesis of malignant tumour metastasis. We also list the roles of glutamine in resisting oxidative stress and promoting immune escape. Finally, the significance of targeting glutamine metabolism in inhibiting tumour metastasis was proposed, research in this field improving our understanding of amino acid metabolism rewiring and simultaneously bringing about new and exciting therapeutic prospects.

Identification of a novel therapeutic target for lung cancer: Mitochondrial ribosome protein L9

Lung cancer has a high fatality rate and incidence rate. At present, the initial and progress mechanism of lung cancer has not been completely elucidated and new therapeutic targets still need to be developed. In this study, the screening process was based on lung cancer expression profile data and survival analysis. Mitochondrial ribosome protein L9 (MRPL9) was upregulated in lung cancer tissues and related to the poor overall survival rate and recurrence-free survival rate of lung cancer patients. Knockdown of MRPL9 inhibited the proliferation, sphere-formation, and migration ability of lung cancer cells. MRPL9 was associated with the c-MYC signaling pathway, and lung cancer patients with high expression of both MRPL9 and MYC had a poor prognosis. Furthermore, c-MYC was associated with the epithelial-mesenchymal transition (EMT) regulatory protein zinc finger E-box binding homeobox 1 (ZEB1) by bioinformatics analysis. The relationship between ZEB1 and c-MYC was further confirmed by interfering with c-MYC expression. MRPL9 is a potential therapeutic target for lung cancer and exerts its biological functions by affecting the transcription factor c-MYC thereby regulating the EMT regulator ZEB1.

c-Myc protects hepatocellular carcinoma cell from ferroptosis induced by glutamine deprivation via upregulating GOT1 and Nrf2

BACKGROUND

Glutamine metabolism is critical for development of hepatocellular carcinoma (HCC), which makes it a novel promising treatment target. However, clinical evidence suggested glutamine withdrawal therapy does not achieved the desired tumor suppression. Therefore, it is valuable to investigate the survival mechanisms of tumors with glutamine deprivation.

METHODS

The HCC cells were cultured in glutamine-free medium or supplemented with glutamine metabolites or ferroptosis inhibitors. The parameters related to ferroptosis and the activity of GSH synthesis-related enzymes of the HCC cells were detected by corresponding kits. The expressions of glutamate oxaloacetate transaminase 1 (GOT1), c-Myc and Nrf2 were detected by western blot and qRT-PCR. The chromatin immunoprecipitation and luciferase reporter assays were performed to investigate the correlation between c-Myc and GOT1. The siRNAs of c-Myc and GOT1 were used to explore their roles in GSH (GSH) synthesis and ferroptosis in vitro and in vivo.

RESULTS

Glutamine deprivation-induced ferroptosis did not completely inhibit HCC cells proliferation. Glutamine deprivation activated the expression of c-Myc, which promoted the transcription of GOT1 and Nrf2, consequently maintaining the GSH synthesis and inhibiting ferroptosis. In addition, combined inhibition of GOT1 with glutamine deprivation could result in better inhibition of HCC in vitro and in vivo.

CONCLUSIONS

In our work, the results indicate that GOT1 induced by c-Myc may play an important role in combating ferroptosis due to glutamine deprivation, making it a significant target in glutamine withdrawal therapy. This study provides a theoretical foundation for the clinical targeted therapy for HCC.

Identification of novel oncogenes in oral cancer among elderly nonsmokers

OBJECTIVES

In recent years, an increase in oral cancer among elderly nonsmokers has been noted. The aim of this study was to identify novel oncogenes in oral cancer in older nonsmokers.

MATERIAL AND METHODS

Whole-exome sequencing (WES) data from 324 oral cancer patients were obtained from The Cancer Genome Atlas. Single nucleotide variants (SNVs) and insertions/deletions (INDELs) were extracted from the WES data of older patients. Fisher's exact test was performed to determine the specificity of variants in these genes. Finally, SNVs and INDELs were identified by target enrichment sequencing.

RESULTS

Gene ontology analysis of 112 genes with significant SNVs or INDELs in nonsmokers revealed that nonsynonymous SNVs in HECTD4 were significantly more frequent in nonsmokers than in smokers by target enrichment sequencing (p = .02).

CONCLUSIONS

Further investigation of the function of HECTD4 variants as oncogenes in older nonsmokers is warranted.

Evaluation of Metabolomics as Diagnostic Targets in Oral Squamous Cell Carcinoma: A Systematic Review

In recent years, high-throughput technologies have facilitated the widespread use of metabolomics to identify biomarkers and targets for oral squamous cell carcinoma (OSCC). As a result, the primary goal of this systematic review is to identify and evaluate metabolite biomarkers and their pathways for OSCC that featured consistently across studies despite methodological variations. Six electronic databases (Medline, Cochrane, Web of Science, CINAHL, ProQuest, and Embase) were reviewed for the longitudinal studies involving OSCC patients and metabolic marker analysis (in accordance with PRISMA 2020). The studies included ranged from the inception of metabolomics in OSCC (i.e., 1 January 2007) to 30 April 2023. The included studies were then assessed for their quality using the modified version of NIH quality assessment tool and QUADOMICS. Thirteen studies were included after screening 2285 studies. The majority of the studies were from South Asian regions, and metabolites were most frequently derived from saliva. Amino acids accounted for more than quarter of the detected metabolites, with glutamate and methionine being the most prominent. The top dysregulated metabolites indicated dysregulation of six significantly enriched pathways including aminoacyl-tRNA biosynthesis, glutathione metabolism and arginine biosynthesis with the false discovery rate (FDR) <0.05. Finally, this review highlights the potential of metabolomics for early diagnosis and therapeutic targeting of OSCC. However, larger studies and standardized protocols are needed to validate these findings and make them a clinical reality.

Stonin 2 activates lysosomal-mTOR axis for cell survival in oral cancer

Aberrant expression of various genes is associated with the progression of oral squamous cell carcinoma. Stonin 2, an endocytic protein, has a prominent role in clathrin-associated endocytosis. Its position in oral cancer is still unknown. Here, we report that STON2 expression increases with an increase in the grade of the oral cancer tissue. Further, STON2 overexpressed cells possess a higher rate of proliferation and migraton in oral cancer cells. STON2 helps maintain lysosomal functions by preserving the lysosomal membrane integrity. It activates the Akt-mTOR axis and retains the mTOR on the membrane of the lysosomes. Further, we have identified an inhibitor of STON2, i.e., Trifluoperazine dihydrochloride (TFP), which targets the lysosomal axis by disrupting the Akt-mTOR pathway and causes lysosomal membrane permeabilization. Intererstingly, TFP shows a decrease in cell vaibility on the oral cancer cells and it was observed that cell viability is restored in TFP-treated STON2 overexpressed cells. Moreover, the lysosomal activity and the Akt-mTOR expression are restored in STON2 overexpressed cells co-treated with TFP, establishing TFP targets STON2 to showcase its anti-cancer effects in oral cancer. In conclusion, STON2 might serve as a potential biomarker in oral cancer, and its inhibition could functions as a novel anti-cancer mechanims against oral cancer.

Emerging role of mRNA methylation in regulating the hallmarks of cancer

The dynamic chemical modifications of DNA, RNA, and proteins can transform normal cells into malignant ones. While the DNA and protein modifications in cancer have been described extensively in the literature, there are fewer reports about the role of RNA modifications in cancer. There are over 100 forms of RNA modifications and one of these, mRNA methylation, plays a critical role in the malignant properties of the cells. mRNA methylation is a reversible modification responsible for regulating protein expression at the post-transcriptional level. Despite being discovered in the 1970s, a complete understanding of the different proteins involved and the mechanism behind mRNA methylation remains largely unknown. However, these mRNA methylations have been shown to foster cancer hallmarks via specific cellular targets inside the cell. In this review, we provide a brief overview of mRNA methylation and its emerging role in regulating the various hallmarks of cancer.

HPV16 E6 and E7 Oncoproteins Stimulate the Glutamine Pathway Maintaining Cell Proliferation in a SNAT1-Dependent Fashion

Persistent high-risk human papillomavirus infection is the main risk factor for cervical cancer establishment, where the viral oncogenes E6 and E7 promote a cancerous phenotype. Metabolic reprogramming in cancer involves alterations in glutamine metabolism, also named glutaminolysis, to provide energy for supporting cancer processes including migration, proliferation, and production of reactive oxygen species, among others. The aim of this work was to analyze the effect of HPV16 E6 and E7 oncoproteins on the regulation of glutaminolysis and its contribution to cell proliferation. We found that the E6 and E7 oncoproteins exacerbate cell proliferation in a glutamine-dependent manner. Both oncoproteins increased the levels of transporter SNAT1, as well as GLS2 and GS enzymes; E6 also increased LAT1 transporter protein levels, while E7 increased ASCT2 and xCT. Some of these alterations are also regulated at a transcriptional level. Consistently, the amount of SNAT1 protein decreased in Ca Ski cells when E6 and E7 expression was knocked down. In addition, we demonstrated that cell proliferation was partially dependent on SNAT1 in the presence of glutamine. Interestingly, SNAT1 expression was higher in cervical cancer compared with normal cervical cells. The high expression of SNAT1 was associated with poor overall survival of cervical cancer patients. Our results indicate that HPV oncoproteins exacerbate glutaminolysis supporting the malignant phenotype.

Therapeutic Targeting of Glutaminolysis as a Novel Strategy to Combat Cancer Stem Cells

Rare subpopulations of cancer stem cells (CSCs) have the ability to self-renew and are the primary driving force behind cancer metastatic dissemination and the preeminent hurdle to cancer treatment. As opposed to differentiated, non-malignant tumor offspring, CSCs have sophisticated metabolic patterns that, depending on the kind of cancer, rely mostly on the oxidation of major fuel substrates such as glucose, glutamine, and fatty acids for survival. Glutaminolysis is a series of metabolic reactions that convert glutamine to glutamate and, eventually, α-ketoglutarate, an intermediate in the tricarboxylic acid (TCA) cycle that provides biosynthetic building blocks. These building blocks are mostly utilized in the synthesis of macromolecules and antioxidants for redox homeostasis. A recent study revealed the cellular and molecular interconnections between glutamine and cancer stemness in the cell. Researchers have increasingly focused on glutamine catabolism in their attempt to discover an effective therapy for cancer stem cells. Targeting catalytic enzymes in glutaminolysis, such as glutaminase (GLS), is achievable with small molecule inhibitors, some of which are in early-phase clinical trials and have promising safety profiles. This review summarizes the current findings in glutaminolysis of CSCs and focuses on novel cancer therapies that target glutaminolysis in CSCs.

Taohong Siwu Decoction exerts anticancer effects on breast cancer via regulating MYC, BIRC5, EGF and PIK3R1 revealed by HTS2 technology

Taohong Siwu Decoction (TSD), a classical gynecological prescription that was firstly reported 600 years ago, has been widely used in the adjuvant treatment of breast cancer (BRCA) in China. However, the mechanism of action of TSD in treating BRCA has remained unclear. Here, high-throughput sequencing-based high-throughput screening (HTS²) technology was used to reveal the molecular mechanism of TSD, combination with bioinformatics and systems pharmacology in this study. Firstly, our results showed that TSD exerts an anticancer effect on BRCA cells by inhibiting cell proliferation, migration and inducing apoptosis as well as cell-cycle arrest. And our results from HTS² suggested that herbs of TSD could significantly inhibit KRAS pathway and pathway in cancer, and activate apoptosis pathway, p53 pathway and hypoxia pathway, which may lead to the anticancer function of TSD. Further, we found that TSD clearly regulates MYC, BIRC5, EGF, and PIK3R1 genes, which play an important role in the development and progression of tumor and have significant correlation with overall survival in BRCA patients. By molecular docking, we discovered that Pentagalloylglucose, a compound derived from TSD, might directly bind to and inhibit the function of BRD4, which is a reported transcriptional activator of MYC gene, and thus repress the expression of MYC. Taken together, this study explores the mechanism of TSD in anti-BRCA by combining HTS² technology, bioinformatics analysis and systems pharmacology.

Identification of Metabolism-Associated Biomarkers for Early and Precise Diagnosis of Oral Squamous Cell Carcinoma

The 5-year survival rate for oral squamous cell carcinoma (OSCC), one of the most common head and neck cancers, has not improved in the last 20 years. Poor prognosis of OSCC is the result of failure in early and precise diagnosis. Metabolic reprogramming, including the alteration of the uptake and utilisation of glucose, amino acids and lipids, is an important feature of OSCC and can be used to identify its biomarkers for early and precise diagnosis. In this review, we summarise how recent findings of rewired metabolic networks in OSCC have facilitated early and precise diagnosis of OSCC.

Lactate-related metabolic reprogramming and immune regulation in colorectal cancer

Changes in cellular metabolism involving fuel sources are well-known mechanisms of cancer cell differentiation in the context of carcinogenesis. Metabolic reprogramming is regulated by oncogenic signaling and transcriptional networks and has been identified as an essential component of malignant transformation. Hypoxic and acidified tumor microenvironment contributes mainly to the production of glycolytic products known as lactate. Mounting evidence suggests that lactate in the tumor microenvironment of colorectal cancer(CRC) contributes to cancer therapeutic resistance and metastasis. The contents related to the regulatory effects of lactate on metabolism, immune response, and intercellular communication in the tumor microenvironment of CRC are also constantly updated. Here we summarize the latest studies about the pleiotropic effects of lactate in CRC and the clinical value of targeting lactate metabolism as treatment. Different effects of lactate on various immune cell types, microenvironment characteristics, and pathophysiological processes have also emerged. Potential specific therapeutic targeting of CRC lactate metabolism is also discussed. With increased knowledge, effective druggable targets might be identified, with the aim of improving treatment outcomes by reducing chemoresistance.

Targeting Myc Interacting Proteins as a Winding Path in Cancer Therapy

MYC, as a well-known oncogene, plays essential roles in promoting tumor occurrence, development, invasion and metastasis in many kinds of solid tumors and hematologic neoplasms. In tumors, the low expression and the short half-life of Myc are reversed, cause tumorigenesis. And proteins that directly interact with different Myc domains have exerted a significant impact in the process of Myc-driven carcinogenesis. Apart from affecting the transcription of Myc target genes, Myc interaction proteins also regulate the stability of Myc through acetylation, methylation, phosphorylation and other post-translational modifications, as well as competitive combination with Myc. In this review, we summarize a series of Myc interacting proteins and recent advances in the related inhibitors, hoping that can provide new opportunities for Myc-driven cancer treatment.

Therapeutic Potential of the Cyclin-Dependent Kinase Inhibitor Flavopiridol on c-Myc Overexpressing Esophageal Cancer

Tumors with elevated c-Myc expression often exhibit a highly aggressive phenotype, and c-Myc amplification has been shown to be frequent in esophageal cancer. Emerging data suggests that synthetic lethal interactions between c-Myc pathway activation and small molecules inhibition involved in cell cycle signaling can be therapeutically exploited to preferentially kill tumor cells. We therefore investigated whether exploiting elevated c-Myc expression is effective in treating esophageal cancer with the CDK inhibitor flavopiridol. We found frequent overexpression of c-Myc in human esophageal cancer cell lines and tissues. c-Myc overexpression correlated with accelerated esophageal cancer subcutaneous xenograft tumor growth. Esophageal cancer cells with elevated c-Myc expression were found preferentially more sensitive to induction of apoptosis by the CDK inhibition flavopiridol compared to esophageal cancer cells with lower c-Myc expression. In addition, we observed that flavopiridol alone or in combination with the chemotherapeutic agent nanoparticle albumin-bound paclitaxel (NPT) or in combinations with the targeted agent BMS-754807 significantly inhibited esophageal cancer cell proliferation and subcutaneous xenograft tumor growth while significantly enhancing overall mice survival. These results indicate that aggressive esophageal cancer cells with elevated c-Myc expression are sensitive to the CDK inhibitor flavopiridol, and that flavopiridol alone or in combination can be a potential therapy for c-Myc overexpressing esophageal cancer.

Role of glutamine and its metabolite ammonia in crosstalk of cancer-associated fibroblasts and cancer cells

Cancer-associated fibroblasts (CAFs), the most abundant cells in the tumor microenvironment, play an indispensable role in cancer initiation, progression, metastasis, and metabolism. The limitations of traditional treatments can be partly attributed to the lack of understanding of the role of the tumor stroma. For this reason, CAF targeting is gradually gaining attention, and many studies are trying to overcome the limitations of tumor treatment with CAF as a breakthrough. Glutamine (GLN) has been called a “nitrogen reservoir” for cancer cells because of its role in supporting anabolic processes such as fuel proliferation and nucleotide synthesis, but ammonia is a byproduct of the metabolism of GLN and other nitrogenous compounds. Moreover, in some studies, GLN has been reported as a fundamental nitrogen source that can support tumor biomass. In this review, we discuss the latest findings on the role of GLN and ammonia in the crosstalk between CAFs and cancer cells as well as the potential therapeutic implications of nitrogen metabolism.

Metabolic reprogramming by traditional Chinese medicine and its role in effective cancer therapy

Metabolic reprogramming, characterized by alterations of cellular metabolic patterns, is fundamentally important in supporting the malignant behaviors of cancer cells. It is considered as a promising therapeutic target against cancer. Traditional Chinese medicine (TCM) and its bioactive components have been used in cancer therapy for an extended period, and they are well-known for their multi-target pharmacological functions and fewer side effects. However, the detailed and advanced mechanisms underlying the anticancer activities of TCM remain obscure. In this review, we summarized the critical processes of cancer cell metabolic reprogramming, including glycolysis, mitochondrial oxidative phosphorylation, glutaminolysis, and fatty acid biosynthesis. Moreover, we systemically reviewed the regulatory effects of TCM and its bioactive ingredients on metabolic enzymes and/or signal pathways that may impede cancer progress. A total of 46 kinds of TCMs was reported to exert antitumor effects and/or act as chemosensitizers via regulating metabolic processes of cancer cells, and multiple targets and signaling pathways were revealed to contribute to the metabolic-modulating functions of TCM. In conclusion, TCM has its advantages in ameliorating cancer cell metabolic reprogramming by its poly-pharmacological actions. This review may shed some new light on the explicit recognition of the mechanisms of anticancer actions of TCM, leading to the development of natural antitumor drugs based on reshaping cancer cell metabolism.

c-Myc-induced circ-NOTCH1 promotes aggressive phenotypes of nasopharyngeal carcinoma cells by regulating the miR-34c-5p/c-Myc axis

Nasopharyngeal carcinoma (NPC) is the subclass of head and neck cancer with the highest incidence among otolaryngology malignancies. A growing amount of evidence has proven that circular RNAs (circRNAs) play key roles in the progression of multiple cancers. It has been reported that circ-NOTCH1 is a novel circRNA and functions as an oncogene in gastric cancer, while the regulatory mechanism of circ-NOTCH1 in NPC remains unknown. In the present research, our findings revealed that circ-NOTCH1 was overexpressed in NPC tissues and cells. Circ-NOTCH1 knockdown suppressed NPC cell proliferation, invasion, and migration. Subsequently, we discovered that c-Myc can activate circ-NOTCH1 by binding to the NOTCH1 promoter. c-Myc functioned as a tumor promoter in NPC cells. Mechanistically, circ-NOTCH1 served as a competitive endogenous RNA to modulate c-Myc expression by sponging miR-34c-5p. Additionally, overexpression of c-Myc reversed the circ-NOTCH1 knockdown-mediated inhibition of NPC cellular progression. Overall, this study suggested that c-Myc-induced circ-NOTCH1 promoted malignant phenotypes of NPC cells by regulating the miR-34c-5p/c-Myc axis.

Targeting a novel LncRNA SNHG15/miR-451/c-Myc signaling cascade is effective to hamper the pathogenesis of breast cancer (BC) in vitro and in vivo

BACKGROUND

To our knowledge, LncRNA SNHG15 exerted its tumor-promoting effects to facilitate the development of breast cancer (BC), but there still needed more data to elucidate the potential underlying mechanisms.

METHODS

We examined genes expression status by performing Real-Time qPCR and Western Blot analysis, and cellular functions, including cell proliferation, viability, apoptosis, mobility, were measured by using the CCK-8 assay, colony formation assay, trypan blue staining assay, flow cytometer (FCM), transwell assay and wound scratch assay, respectively. The predicted targeting sites in LncRNA SNHG15, miR-451 and c-Myc 3'UTR were validated by dual-luciferase reporter gene system assay. Finally, we established the tumor-bearing mice models, and the expression status, including its enrichment and cellular localization were examined by immunohistochemistry (IHC) assay.

RESULTS

Our data indicated LncRNA SNHG15 upregulated c-Myc to facilitate BC progression by sponging miR-451 in a competing endogenous RNA (ceRNA)-dependent manner in vitro and in vivo. Specifically, LncRNA SNHG15 and c-Myc were upregulated, while miR-451 was downregulated in BC cells and clinical tissues, compared to their normal counterparts. In addition, miR-451 negatively correlated with LncRNA SNHG15 and c-Myc, and LncRNA SNHG15 was positively relevant to c-Myc in BC tissues. Next, we validated that LncRNA SNHG15 sponged miR-451 to upregulate c-Myc in BC cells. Further gain- and loss-of-function experiments evidenced that LncRNA SNHG15 promoted, while miR-451 inhibited malignant phenotypes, including cell proliferation, viability, migration, invasion and epithelial-mesenchymal transition (EMT) in BC cells. Interestingly, the inhibiting effects of LncRNA SNHG15 ablation on BC progression were abrogated by both silencing miR-451 and overexpressing c-Myc.

CONCLUSIONS

We concluded that targeting the LncRNA SNHG15/miR-451/c-Myc signaling cascade was novel to hamper BC progression, which broadened our knowledge in this field, and provided potential biomarkers for BC diagnosis and treatment.

Glutaminolysis is a metabolic route essential for survival and growth of prostate cancer cells and a target of 5α-dihydrotestosterone regulation

PURPOSE

Resistance to androgen-deprivation therapies and progression to so-called castrate-resistant prostate cancer (CRPC) remain challenges in prostate cancer (PCa) management and treatment. Among other alterations, CRPC has been associated with metabolic reprogramming driven by androgens. Here, we investigated the role of androgens in regulating glutaminolysis in PCa cells and determined the relevance of this metabolic route in controlling the survival and growth of androgen-sensitive (LNCaP) and CRPC (DU145 and PC3) cells.

METHODS

PCa cells (LNCaP, DU145 and PC3) and 3-month old rats were treated with 5α-dihydrotestosterone (DHT). Alternatively, LNCaP cells were exposed to the glutaminase inhibitor BPTES, alone or in combination with the anti-androgen bicalutamide. Biochemical, Western blot and extracellular flux assays were used to evaluate the viability, proliferation, migration and metabolism of PCa cells in response to DHT treatment or glutaminase inhibition.

RESULTS

We found that DHT up-regulated the expression of the glutamine transporter ASCT2 and glutaminase, both in vitro in LNCaP cells and in vivo in rat prostate cells. BPTES diminished the viability and migration of PCa cells, while increasing caspase-3 activity. CRPC cells were found to be more dependent on glutamine and more sensitive to glutaminase inhibition. BPTES and bicalutamide co-treatment had an additive effect on suppressing LNCaP cell viability. Finally, we found that inhibition of glutaminolysis differentially affected glycolysis and lipid metabolism in both androgen-sensitive and CRPC cells.

CONCLUSION

Our data reveal glutaminolysis as a central metabolic route controlling PCa cell fate and highlight the relevance of targeting glutaminase for CRPC treatment.

Targeting YTHDF1 effectively re-sensitizes cisplatin-resistant colon cancer cells by modulating GLS-mediated glutamine metabolism

Colorectal cancer (CRC) has a high mortality rate and poor prognosis. Despite chemotherapeutic agents such as cisplatin, which has achieved a better prognosis and survival rate against cancer, drug resistance leads to significant challenges. Accumulating evidence suggests that YTHDF1, the N ⁶-methyladenosine (m6A) "reader," is an important regulator in tumor progresses. Herein, we report that YTHDF1 was significantly upregulated in human colon tumors and cell lines. Overexpression of YTHDF1 decreased the cisplatin sensitivity of colon cancer cells. From the established cisplatin-resistant CRC cell line (LoVo CDDP R), we detected that YTHDF1 was significantly upregulated in cisplatin-resistant CRC cells. Intriguingly, RNA sequencing (RNA-seq) results revealed that glutamine metabolism enzymes were clearly upregulated in LoVo CDDP R cells. Glutamine uptake, that is, glutaminase (GLS) activity, was upregulated in LoVo CDDP R cells. Furthermore, bioinformatics analysis indicated that the 3' UTR of GLS1 contained a putative binding motif of YTHDF1, and an interaction was further validated by a protein-RNA interaction assay (RNA immunoprecipitation [RIP]). Furthermore, we demonstrated that YTHDF1 promoted protein synthesis of GLS1. Inhibiting GLS1 effectively synergizes with cisplatin to induce colon cancer cell death. Finally, that YTHDF1 mediated cisplatin through the GLS1-glutamine metabolism axis was validated by an in vivo xenograft mouse model. In summary, our study reveals a new mechanism for YTHDF1-promoted cisplatin resistance, contributing to overcoming chemoresistant colon cancers.

Blocking Myc to Treat Cancer: Reflecting on Two Decades of Omomyc

First designed and published in 1998 as a laboratory tool to study Myc perturbation, Omomyc has come a long way in the past 22 years. This dominant negative has contributed to our understanding of Myc biology when expressed, first, in normal and cancer cells, and later in genetically-engineered mice, and has shown remarkable anti-cancer properties in a wide range of tumor types. The recently described therapeutic effect of purified Omomyc mini-protein—following the surprising discovery of its cell-penetrating capacity—constitutes a paradigm shift. Now, much more than a proof of concept, the most characterized Myc inhibitor to date is advancing in its drug development pipeline, pushing Myc inhibition into the clinic.

miR-362 knock-down promotes proliferation and inhibits apoptosis in porcine immature Sertoli cells by targeting the RMI1 gene

Immature Sertoli cell proliferation determines the total number of mature Sertoli cells and further regulates normal spermatogenesis. Accumulating evidence demonstrates that microRNAs (miRNAs) play regulatory roles in immature Sertoli cell proliferation, while the functions and mechanisms of the Sertoli cells of domestic animals are poorly understood. In the present study, we aimed to investigate the roles of miR-362 in cell proliferation and apoptosis of porcine immature Sertoli cells. The results showed that miR-362 inhibition promoted the entrance of cells into the S phase and increased the expressions of cell cycle-related genes c-MYC, CNNE1, CCND1 and CDK4. Knock-down of miR-362 also promoted cell proliferation and inhibited apoptosis, which was demonstrated by the results from cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU) and Annexin V-FITC/PI staining assays. The recQ-mediated genome instability protein 1 (RMI1) gene was identified as a potential target gene of miR-362 via luciferase reporter assay, and miR-362 repressed the protein expression of RMI1 in porcine immature Sertoli cells. siRNA-induced RMI1 knock-down further abolished the effects of miR-362 inhibition on porcine immature Sertoli cells. Collectively, we concluded that miR-362 knock-down promotes proliferation and inhibits apoptosis in porcine immature Sertoli cells by targeting the RMI1 gene, which indicates that miR-362 determines the fate of immature Sertoli cells.