Project description:Background: Hepatocellular carcinoma (HCC) cells undergo reprogramming of glucose metabolism to support uncontrolled proliferation, of which the intrinsic mechanism still merits further investigation. Although regulatory factor X6 (RFX6) is aberrantly expressed in different cancers, its precise role in cancer development remains ambiguous. Methods: Microarrays of HCC tissues were employed to investigate the expression of RFX6 in tumor and adjacent non-neoplastic tissues. Functional assays were employed to explore the role of RFX6 in HCC development. Chromatin immunoprecipitation (ChIP), untargeted metabolome profiling, and sequencing were performed to identify potential downstream genes and pathways regulated by RFX6. Metabolic assays were employed to investigate the effect of RFX6 on glycolysis in HCC cells. Bioinformatics databases were used to validate the above findings. Results: HCC tissues exhibited elevated expression of RFX6. High RFX6 expression represented as an independent hazard factor correlated to poor prognosis in patients with HCC. RFX6 deficiency inhibited HCC development in vitro and in vivo, while its overexpression exerted opposite functions. Mechanistically, RFX6 bound to the promoter area of PGAM1 and upregulated its expression. The increased PGAM1 protein levels enhanced glycolysis and further promoted the development of HCC. Conclusions: RFX6 acted as a novel driver for HCC development by promoting aerobic glycolysis, disclosing the potential of the RFX6-PGAM1 axis for therapeutic targeting.
Project description:Background: Hepatocellular carcinoma (HCC) cells undergo reprogramming of glucose metabolism to support uncontrolled proliferation, of which the intrinsic mechanism still merits further investigation. Although regulatory factor X6 (RFX6) is aberrantly expressed in different cancers, its precise role in cancer development remains ambiguous. Methods: Microarrays of HCC tissues were employed to investigate the expression of RFX6 in tumor and adjacent non-neoplastic tissues. Functional assays were employed to explore the role of RFX6 in HCC development. Chromatin immunoprecipitation (ChIP), untargeted metabolome profiling, and sequencing were performed to identify potential downstream genes and pathways regulated by RFX6. Metabolic assays were employed to investigate the effect of RFX6 on glycolysis in HCC cells. Bioinformatics databases were used to validate the above findings. Results: HCC tissues exhibited elevated expression of RFX6. High RFX6 expression represented as an independent hazard factor correlated to poor prognosis in patients with HCC. RFX6 deficiency inhibited HCC development in vitro and in vivo, while its overexpression exerted opposite functions. Mechanistically, RFX6 bound to the promoter area of PGAM1 and upregulated its expression. The increased PGAM1 protein levels enhanced glycolysis and further promoted the development of HCC. Conclusions: RFX6 acted as a novel driver for HCC development by promoting aerobic glycolysis, disclosing the potential of the RFX6-PGAM1 axis for therapeutic targeting.
Project description:BackgroundHepatocellular carcinoma (HCC) cells undergo reprogramming of glucose metabolism to support uncontrolled proliferation, of which the intrinsic mechanism still merits further investigation. Although regulatory factor X6 (RFX6) is aberrantly expressed in different cancers, its precise role in cancer development remains ambiguous.MethodsMicroarrays of HCC tissues were employed to investigate the expression of RFX6 in tumour and adjacent non-neoplastic tissues. Functional assays were employed to explore the role of RFX6 in HCC development. Chromatin immunoprecipitation, untargeted metabolome profiling and sequencing were performed to identify potential downstream genes and pathways regulated by RFX6. Metabolic assays were employed to investigate the effect of RFX6 on glycolysis in HCC cells. Bioinformatics databases were used to validate the above findings.ResultsHCC tissues exhibited elevated expression of RFX6. High RFX6 expression represented as an independent hazard factor correlated to poor prognosis in patients with HCC. RFX6 deficiency inhibited HCC development in vitro and in vivo, while its overexpression exerted opposite functions. Mechanistically, RFX6 bound to the promoter area of phosphoglycerate mutase 1 (PGAM1) and upregulated its expression. The increased PGAM1 protein levels enhanced glycolysis and further promoted the development of HCC.ConclusionsRFX6 acted as a novel driver for HCC development by promoting aerobic glycolysis, disclosing the potential of the RFX6-PGAM1 axis for therapeutic targeting.
Project description:Phosphoglycerate mutase 1 (PGAM1) is a key-node enzyme that diverts the metabolic intermediates from glycolysis into its shunts to support macromolecule biosynthesis for rapid and sustainable cell proliferation. It is prevalent that PGAM1 activity is upregulated in various tumors; however, the underlying mechanism remains unclear. Here, we unveil that pyruvate kinase M2 (PKM2) moonlights as a histidine kinase in a phosphoenolpyruvate (PEP)-dependent manner to catalyze PGAM1 H11 phosphorylation, that is essential for PGAM1 activity. Moreover, the dimeric or monomeric PKM2 in tumor cells phosphorylates PGAM1 more efficiently than the tetrameric one. In response to epidermal growth factor (EGF), Src signaling triggered PGAM1 Y119 phosphorylation is a prerequisite for PKM2 binding and the subsequent H11 phosphorylation of PGAM1, which constitutes the discrepancy between tumor cells and normal ones. A PGAM1-derived pY119-containing cell-permeable peptide or Y119 mutation disrupts the interaction of PGAM1 with PKM2 and its H11 phosphorylation, and eventually dampens the glycolysis shunts and tumor growth. We not only identifes a histidine kinase function of PKM2, but also illustrates an enzymes-cross-talk regulatory mode during metabolic reprogramming.
Project description:Phosphoglycerate mutase 1 (PGAM1) is a key node enzyme that diverts the metabolic reactions from glycolysis into its shunts to support macromolecule biosynthesis for rapid and sustainable cell proliferation. It is prevalent that PGAM1 activity is upregulated in various tumors; however, the underlying mechanism remains unclear. Here, we unveil that pyruvate kinase M2 (PKM2) moonlights as a histidine kinase in a phosphoenolpyruvate (PEP)-dependent manner to catalyze PGAM1 H11 phosphorylation, that is essential for PGAM1 activity. Moreover, monomeric and dimeric PKM2 are efficient to phosphorylate and activate PGAM1, while the tetrameric PKM2 is not. In response to epidermal growth factor (EGF) signaling, Src-catalyzed PGAM1 Y119 phosphorylation is a prerequisite for PKM2 binding and the subsequent PGAM1 H11 phosphorylation, which constitutes the discrepancy between tumor cells and normal ones. A PGAM1-derived pY119-containing cell-permeable peptide or Y119 mutation disrupted the interaction of PGAM1 with PKM2 and its H11 phosphorylation, and eventually dampened the glycolysis shunts and tumor growth. We not only identified a function of PKM2 as a histidine kinase, but also illustrated an enzymes-cross-talk regulatory mode during metabolic reprogramming.
Project description:Understanding the mechanisms underlying evasive resistance in cancer is an unmet medical need to improve the efficacy of current therapies. In hepatocellular carcinoma (HCC), aberrant expression of hypoxia inducible factor 1 a (HIF1a) and increased aerobic glycolysis metabolism represent drivers of the development of resistance to therapy with the multi-kinase inhibitor Sorafenib. However, it has remained unknown how HIF1a is activated and how its activity and the subsequent induction of aerobic glycolysis promotes Sorafenib resistance in HCC. Here, we report the ubiquitin-specific peptidase USP29 as a new regulator of HIF1a and of aerobic glycolysis during the development of Sorafenib resistance in HCC. In particular, we have identified USP29 as a critical deubiquitylase (DUB) of HIF1a, which directly deubiquitinates and stabilizes HIF1a and, thus, promotes its transcriptional activity. Among the transcriptional targets of HIF1a is the gene encoding for hexokinase 2 (HK2), a key enzyme of the glycolytic pathway. The absence of USP29, and thus of HIF1a transcriptional activity, reduces the levels of aerobic glycolysis and reinstalls the sensitivity to Sorafenib treatment in Sorafenib-resistant HCC cells in vitro and in xenograft transplantation mouse models in vivo. Notably, the absence of USP29 and high HK2 expression levels correlate with the response of HCC patients to Sorafenib therapy. Together, the data demonstrate that, as a DUB of HIF1a, USP29 promotes Sorafenib resistance in HCC cells by upregulating glycolysis, thereby opening new avenues for therapeutically targeting Sorafenib-resistant HCC in patients.
Project description:Understanding the mechanisms of the Warburg shift to aerobic glycolysis is central to defining the metabolic basis of cancer. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an aggressive cancer characterized by bi-allelic inactivation of the gene encoding the Krebs cycle enzyme fumarate hydratase, an early shift to aerobic glycolysis, and rapid metastasis. We observed of the mitochondrial in tumors from HLRCC patients. Biochemical and transcriptomics analyses revealed that respiratory chain dysfunction in the tumors was due to loss of expression of mitochondrial DNA (mtDNA)-encoded subunits of respiratory chain complexes, caused by a marked decrease in mtDNA content and increased mtDNA mutations. We demonstrated that accumulation of fumarate in HLRCC tumors inactivated the core factors responsible for replication and proofreading of mtDNA, leading to loss of expression of respiratory chain components, thereby promoting the shift to aerobic glycolysis and disease progression in this prototypic model of glucose-dependent human cancer.