RFX6 facilitates aerobic glycolysis-mediated growth and metastasis of hepatocellular carcinoma through targeting PGAM1 [RNA-Seq]
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ABSTRACT: 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: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:To analyze the gene expression profile of BAT and gWAT from Pgam1 depletion mice, we performed whole genome microarray expression profiling using brown adipose tissue (BAT) and gonadal white adipose tissue (gWAT) from adipose tissue-specific Pgam1 knockout (KO) mice.
Project description:Epidydimal WAT from adipose tissue Pgam1 deficient mice shows the phenotype of beiging. We used single cell RNA sequencing (scRNA-seq) to characterize the beiging cells in gWAT.
Project description:Protein lysine acetylation is a vital post-translational modification (PTM) that plays important roles in biological processes and human diseases. However, its potential roles in hepatocellular carcinoma (HCC) development remain largely unknown. Here we performed a quantitative acetylome analysis of tumor and normal liver tissues from HCC patients. Overall, we identified 792 lysine acetylation sites in 415 proteins, and almost half of their acetylation levels were significantly changed in HCC tumor tissues. The acetylated proteins mainly consisted of metabolic enzymes, which was consistent with the subcellular location analysis that they were primarily located in mitochondria and cytoplasm. Consistently, Bioinformatics analysis showed that differently acetylated proteins were mainly involved in metabolic pathways, such as glycolysis, the tricarboxylic acid (TCA) cycle, fatty acid oxidation, and glutamine metabolism. Then we selected two down-regulated enzymes and verified their acetylation levels in HCC liver tissues. In addition, transcription factors and proteins associated with oxidative stress were identified with aberrant acetylation levels in HCC tumor tissues. Our findings illustrate abundant lysine acetylation sites in HCC liver tissues, which provides insight into the role of lysine acetylation in HCC development, and further contributes to possible implications for its use in diagnose and therapy in the future.
Project description:Tangential sections of 30 µm thickness were taken across the secondary phloem and developing secondary xylem, sections were then pooled to represent the tissues from specific developmental stages. Phloem (P) comprises 3 sections, the cambium (C) - 2 sections, the radial expansion zone (E) - 4 sections, the first to third xylem development zones (X1-X3) - 3 sections each, and the forth to sixth xylem development zones (X4-X6) - 6 sections each.