Carbohydrate response element binding protein (ChREBP) is a glucose-sensing transcription factor that mediates the induction of glycolytic and lipogenic genes in response to glucose. We investigated the expression patterns of ChREBP and glucose transporters (GLUTs) in human hepatocellular carcinoma (HCC) and their association with HCC progression. ChREBP, GLUT2 and GLUT1 immunohistochemistry were performed on liver tissue array containing normal liver tissue, HCC adjacent tissue and cancer tissue of different HCC stages. The effect of HCC malignancy on protein expression was analyzed with one-way ANOVA. The correlations between protein expressions were analyzed with Pearson Correlation test. We found that ChREBP protein expression tended to be positively correlated to liver malignancy. GLUT2 protein expression was significantly reduced in human HCC as compared to normal liver tissue and its expression in HCC was inversely associated to malignancy (p < 0.001). In contrast, GLUT1 was significantly increased in cancer cells and its expression was positively correlated to malignancy (p < 0.001). Furthermore, GLUT1 expression was positively associated to ChREBP expression (r = 0.481, p < 0.0001, n = 70) but negatively correlated to GLUT2 expression (r = −0.320, p = 0.007, n = 70). Notably, ChREBP-expressing hepatocytes did not express GLUT2 but GLUT1. This is the first report unveiling expressions of ChREBP and GLUT2/GLUT1 and their relations in HCC. The expression patterns are related to malignancy and this information would facilitate evaluation of clinical behavior and treatment of HCC.
cancers are characterized by reprogrammed glucose metabolisms to fuel cell growth and proliferation. carbohydrate response element binding protein (chReBp) is a glucose-mediated transcription factor that strongly regulates glycolytic and lipogenic pathways. it has been shown to associate with metabolic diseases, such as obesity, diabetes and non-alcoholic fatty liver diseases. However, how it associates with cancers has not been well understood. In this study, ChREBP expression was assessed by immunohistochemistry in colon tissue arrays containing normal colon tissue and cancer tissue at different clinical stages. Tissue mRNA levels of ChREBP were also measured in a cohort of colon cancer patients. We found that ChREBP mRNA and protein expression were significantly increased in colon cancer tissue compared to healthy colon (p < 0.001), and their expression was positively correlated to colon malignancy (for mRNA, p = 0.002; for protein p < 0.001). Expression of lipogenic genes (ELOVL6 and SCD1) in colon cancer was also positively associated with colon malignancy (for both genes, p < 0.001). In vitro, ChREBP knockdown with siRNA transfection inhibited cell proliferation and induced cell cycle arrest without changes in apoptosis in colon cancer cell lines (HT29, DLD1 and SW480). Glycolytic and lipogenic pathways were inhibited but the p53 pathway was activated after ChREBP knockdown. Taken together, ChREBP expression is associated with colon malignancy and it might contribute to cell proliferation via promoting anabolic pathways and inhibiting p53. In addition, ChREBP might represent a novel clinical useful biomarker to evaluate the malignancy of colon cancer. Carbohydrate response element binding protein (ChREBP) is a basic helix-loop-helix leucine zipper (bHLH-LZ) transcription factor that is mainly expressed in liver, white and brown adipose tissue, intestine, muscle, and pancreatic β-cells 1. It was identified by Uyeda and colleagues in 2001 as the principal mediator of the transcriptional effects of glucose 2. In response to increased glucose levels, ChREBP undergoes dephosphorylation and translocates from the cytoplasm to the nucleus where, it associates with its functional obligatory partner MLX (Max-like interacting protein), to form a heterodimer. This heterodimer binds to carbohydrate responsive elements (ChoRE) of ChREBP target genes in the nucleus 3,4. ChREBP can be activated by glucose metabolites (includes Glucose-6-phosphate, Xylulose-5-phosphate, fructose-2.6-bisphosphate) 5-7 , and by post-translational modifications, such as acetylation 8 and O-GlcNAcylation 9. The ChREBP/MLX heterodimer controls glucose and lipid metabolism via regulating the expression of glycolytic (Pklr, Fk, Glut2, Glut4), gluconeogenic (G6pc), and lipogenic (Fasn, Acc1, Scd1, Elovl6) genes 1,4,10 , suggesting that ChREBP may have an important role in the pathogenesis of metabolic diseases and cancer. So far, most of the studies of ChREBP originated from mouse models and have focused on its function as a hepatic transcription f...
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