The p52-ZER6/G6PD axis alters aerobic glycolysis and promotes tumor progression by activating the pentose phosphate pathway

The NRF2-CARM1 axis links glucose sensing to transcriptional and epigenetic regulation of the pentose phosphate pathway in gastric cancer

Cancer cells autonomously alter metabolic pathways in response to dynamic nutrient conditions in the microenvironment to maintain cell survival and proliferation. A better understanding of these adaptive alterations may reveal the vulnerabilities of cancer cells. Here, we demonstrate that coactivator-associated arginine methyltransferase 1 (CARM1) is frequently overexpressed in gastric cancer and predicts poor prognosis of patients with this cancer. Gastric cancer cells sense a reduced extracellular glucose content, leading to activation of nuclear factor erythroid 2-related factor 2 (NRF2). Subsequently, NRF2 mediates the classic antioxidant pathway to eliminate the accumulation of reactive oxygen species induced by low glucose. We found that NRF2 binds to the CARM1 promoter, upregulating its expression and triggering CARM1-mediated hypermethylation of histone H3 methylated at R arginine 17 (H3R17me2) in the glucose-6-phosphate dehydrogenase gene body. The upregulation of this dehydrogenase, driven by the H3R17me2 modification, redirects glucose carbon flux toward the pentose phosphate pathway. This redirection contributes to nucleotide synthesis (yielding nucleotide precursors, such as ribose-5-phosphate) and redox homeostasis and ultimately facilitates cancer cell survival and growth. NRF2 or CARM1 knockdown results in decreased H3R17me2a accompanied by the reduction of glucose-6-phosphate dehydrogenase under low glucose conditions. Collectively, this study reveals a significant role of CARM1 in regulating the tumor metabolic switch and identifies CARM1 as a potential therapeutic target for gastric cancer treatment.

MAZ-mediated up-regulation of BCKDK reprograms glucose metabolism and promotes growth by regulating glucose-6-phosphate dehydrogenase stability in triple-negative breast cancer

Tumour metabolic reprogramming is pivotal for tumour survival and proliferation. Investigating potential molecular mechanisms within the heterogeneous and clinically aggressive triple-negative breast cancer (TNBC) subtype is essential to identifying novel therapeutic targets. Accordingly, we investigated the role of branched-chain α-keto acid dehydrogenase kinase (BCKDK) in promoting tumorigenesis in TNBC. We analysed The Cancer Genome Atlas dataset and immunohistochemically stained surgical specimens to investigate BCKDK expression and its prognostic implications in TNBC. The effects of BCKDK on tumorigenesis were assessed using cell viability, colony formation, apoptosis, and cell cycle assays, and subsequently validated in vivo. Metabolomic screening was performed via isotope tracer studies. The downstream target was confirmed using mass spectrometry and a co-immunoprecipitation experiment coupled with immunofluorescence analysis. Upstream transcription factors were also examined using chromatin immunoprecipitation and luciferase assays. BCKDK was upregulated in TNBC tumour tissues and associated with poor prognosis. BCKDK depletion led to reduced cell proliferation both in vitro and vivo. MYC-associated zinc finger protein (MAZ) was confirmed as the major transcription factor directly regulating BCKDK expression in TNBC. Mechanistically, BCKDK interacted with glucose-6-phosphate dehydrogenase (G6PD), leading to increased flux in the pentose phosphate pathway for macromolecule synthesis and detoxification of reactive oxygen species. Forced expression of G6PD rescued the growth defect in BCKDK-deficient cells. Notably, the small-molecule inhibitor of BCKDK, 3,6-dichlorobenzo(b)thiophene-2-carboxylic acid, exhibited anti-tumour effects in a patient-derived tumour xenograft model. Our findings hold significant promise for developing targeted therapies aimed at disrupting the MAZ/BCKDK/G6PD signalling pathway, offering potential advancements in treating TNBC through metabolic reprogramming.

RORα inhibits gastric cancer proliferation through attenuating G6PD and PFKFB3 induced glycolytic activity

BACKGROUND

Glycolysis is critical for harvesting abundant energy to maintain the tumor microenvironment in malignant tumors. Retinoic acid-related orphan receptor α (RORα) has been identified as a circadian gene. However, the association of glycolysis with RORα in regulating gastric cancer (GC) proliferation remains poorly understood.

METHODS

Bioinformatic analysis and retrospective study were utilized to explore the role of RORα in cell cycle and glycolysis in GC. The mechanisms were performed in vitro and in vivo including colony formation, Cell Counting Kit-8 (CCK-8), Epithelial- mesenchymal transition (EMT) and subcutaneous tumors of mice model assays. The key drives between RORα and glycolysis were verified through western blot and chip assays. Moreover, we constructed models of high proliferation and high glucose environments to verify a negative feedback and chemoresistance through a series of functional experiments in vitro and in vivo.

RESULTS

RORα was found to be involved in the cell cycle and glycolysis through a gene set enrichment analysis (GSEA) algorithm. GC patients with low RORα expression were not only associated with high circulating tumor cells (CTC) and high vascular endothelial growth factor (VEGF) levels. However, it also presented a positive correlation with the standard uptake value (SUV) level. Moreover, the SUVmax levels showed a positive linear relation with CTC and VEGF levels. In addition, RORα expression levels were associated with glucose 6 phosphate dehydrogenase (G6PD) and phosphofructokinase-2/fructose-2,6-bisphosphatase (PFKFB3) expression levels, and GC patients with low RORα and high G6PD or low RORα and high PFKFB3 expression patterns had poorest disease-free survival (DFS). Functionally, RORα deletion promoted GC proliferation and drove glycolysis in vitro and in vivo. These phenomena were reversed by the RORα activator SR1078. Moreover, RORα deletion promoted GC proliferation through attenuating G6PD and PFKFB3 induced glycolytic activity in vitro and in vivo. Mechanistically, RORα was recruited to the G6PD and PFKFB3 promoters to modulate their transcription. Next, high proliferation and high glucose inhibited RORα expression, which indicated that negative feedback exists in GC. Moreover, RORα deletion improved fluorouracil chemoresistance through inhibition of glucose uptake.

CONCLUSION

RORα might be a novel biomarker and therapeutic target for GC through attenuating glycolysis.

ZNF471 Interacts with BANP to Reduce Tumour Malignancy by Inactivating PI3K/AKT/mTOR Signalling but is Frequently Silenced by Aberrant Promoter Methylation in Renal Cell Carcinoma

Background: Renal cell carcinoma (RCC) is one of the most common malignant tumours of the urinary system. However, the aetiology and pathogenesis of RCC remain unclear. The C2H2 zinc finger protein (ZNF) family is the largest transcriptional regulatory factor family found in mammals, and Krüppel-associated box domain-containing zinc finger proteins (KRAB-ZFPs) constitute the largest subfamily of the C2H2 zinc finger protein family and play an important role in the occurrence and development of tumours. The aim of this study was to explore the role of abnormal methylation of ZNF471 in the development of renal carcinoma. Methods: In this study, we first used the TCGA and EWAS Data Hub databases to analyse the expression and methylation levels of ZNF471 in renal carcinoma tissues and adjacent normal tissues. Second, we collected samples of renal cancer and adjacent normal tissues at Peking University First Hospital to investigate the expression and methylation level of ZNF471 in renal cancer tissues and the relationships between these levels and the clinicopathological features and prognosis of patients with renal cancer. Next, we investigated the effects of ZNF471 on the proliferation, metastasis, cell cycle progression, and apoptosis of renal cell carcinoma cells by cell biology experiments. Finally, we elucidated the underlying molecular mechanisms of ZNF471 in renal cell carcinoma by transcriptome sequencing, bioinformatics analysis and molecular biology experiments. Results: The expression of ZNF471 in renal carcinoma tissues and cell lines was significantly lower than that in adjacent normal tissues and cell lines due to abnormal promoter CpG methylation. Furthermore, the expression of ZNF471 in renal carcinoma tissues was negatively correlated with tumour stage and grade in patients with renal carcinoma. The results of the cell biology experiments showed that ZNF471 could significantly inhibit the proliferation, migration and cell cycle progression of renal cell carcinoma cells and promote apoptosis in these cells. In addition, ZNF471 could interact with BANP and suppress the malignant phenotype of RCC by inactivating the PI3K/AKT/mTOR signalling pathway. Conclusions: As an important tumour suppressor, ZNF471 can interact with BANP in renal cancer cells and inhibit the activation of the PI3K/AKT/mTOR signalling pathway, thereby inhibiting the occurrence and development of renal cancer.

The Emerging Roles of the Metabolic Regulator G6PD in Human Cancers

Metabolic reprogramming, especially reprogrammed glucose metabolism, is a well-known cancer hallmark related to various characteristics of tumor cells, including proliferation, survival, metastasis, and drug resistance. Glucose-6-phosphate dehydrogenase (G6PD) is the first and rate-limiting enzyme of the pentose phosphate pathway (PPP), a branch of glycolysis, that converts glucose-6-phosphate (G6P) into 6-phosphogluconolactone (6PGL). Furthermore, PPP produces ribose-5-phosphate (R5P), which provides sugar-phosphate backbones for nucleotide synthesis as well as nicotinamide adenine dinucleotide phosphate (NADPH), an important cellular reductant. Several studies have shown enhanced G6PD expression and PPP flux in various tumor cells, as well as their correlation with tumor progression through cancer hallmark regulation, especially reprogramming cellular metabolism, sustaining proliferative signaling, resisting cell death, and activating invasion and metastasis. Inhibiting G6PD could suppress tumor cell proliferation, promote cell death, reverse chemoresistance, and inhibit metastasis, suggesting the potential of G6PD as a target for anti-tumor therapeutic strategies. Indeed, while challenges-including side effects-still remain, small-molecule G6PD inhibitors showing potential anti-tumor effect either when used alone or in combination with other anti-tumor drugs have been developed. This review provides an overview of the structural significance of G6PD, its role in and regulation of tumor development and progression, and the strategies explored in relation to G6PD-targeted therapy.

Diagnostic role and immune correlates of programmed cell death-related genes in hepatocellular carcinoma

Programmed cell death (PCD) is thought to have multiple roles in tumors. Here, the roles of PCD-related genes were comprehensively analyzed to evaluate their values in hepatocellular carcinoma (HCC) diagnosis and prognosis. Gene expression and single-cell data of HCC patients, and PCD-related genes were collected from public databases. The diagnostic and prognostic roles of differentially expressed PCD-related genes in HCC were explored by univariate and multivariate Cox regression analyses. Single-cell data were further analyzed for the immune cells and expression of feature genes. Finally, we evaluated the expression of genes by quantitative real-time polymerase chain reaction and Western blot, and the proportion of immune cells was detected by flow cytometry in HCC samples. We obtained 52 differentially expressed PCD-related genes in HCC, based on which the consensus clustering analysis cluster 2 was found to have a worse prognosis than cluster 1. Then 10 feature genes were identified using LASSO analysis, and programmed cell death index (PCDI) was calculated to divided HCC patients into high-PCDI and low-PCDI groups. Worse prognosis was observed in high-PCDI group. Cox regression analysis showed that PCDI is an independent prognostic risk factor for HCC patients. Additionally, SERPINE1 and G6PD of feature genes significantly affect patient survival. Macrophages and Tregs were significantly positively correlated with PCDI. G6PD mainly expressed in macrophages, SERPINE1 mainly expressed in fibroblast. The experimental results confirmed the high expression of SERPINE1 and G6PD in HCC compared with the control, and the infiltration level of macrophages and Treg in HCC was also obviously elevated. PCDI may be a new predictor for the diagnosis of patients with HCC. The association of SERPINE1 and G6PD with the immune environment will provide new clues for HCC therapy.