Senescence Slown Down And Glucose Metabolism Enhanced In Human Colorectal Cancer

Objective: To elucidate the relationship between senescence and reprogramming of glucose metabolism in human colorectal cancers,we investigated the expression of p16,p21 and senescence-related ?-galactosidase(SA-?-Gal),and the key enzymes of glucose metabolism in human colorectal cancer tissues and human colon cancer cells.Methods:1 Human colorectal cancer specimens: The tumor and matched adjacent normal tissues which were over 10 cm from tumor edges,were obtained from 63 patients with colorectal cancer treated with surgery alone at Hebei Medical University Forth Hospital.2 Cell lines: TNF-?-treated human normal colorectal mucosa cell line FHC cells and three human colon cancer cell lines HCT116,HT29,CACO2 cells were detected by MTT assay and SA-?-Gal staining.3 Expression of glucose-6-phosphate dehydrogenase(G6PD)and pyruvate kinase M2(PKM2)Lysates from the fresh colorectal cancer tissues or cells were used to detect the expression of G6 PD and PKM2 by Western blot analysis.Total RNA was extracted and analyzed by real-time fluorescence quantitative polymerase chain reaction(RT-PCR).4 Determination of hexokinase(HK)activity: Operating according to the kit instructions.Results:1 The expression of p16 and p21 was down-regulated and the activity of SA-?-Gal is decreased in human colorectal cancer tissues.Immunohistochemical staining showed that the expression of p16 and p21 in the colorectal cancer tissues was lower than that of the adjacent normal tissues(P<0.05),and SA-?-Gal staining displayed the same pattern as p16 and p21(P<0.05).2 TNF-? treatment decreases SA-?-Gal activity and increases cell viability in human colon cancer cellsThe results from MTT assay and SA-?-Gal staining showed that the activity of SA-?-Gal in HCT116,HT-29 and Caco-2 cells was lower than that of FHC cells(P<0.05).MTT assay indicated that the cell viability of human colon cancer cells was highly increased following induction by TNF-?(P<0.05).3 The expression of G6 PD and PKM2 increases in human colorectal cancer tissues.RT-PCR and Western blot analysis revealed that the mRNA and protein level of G6 PD and PKM2 in human colorectal cancer tissues were higher than that of the adjacent normal tissues(P<0.05).4 The expression and activity of G6 PD,PKM2 and HK increases in the colorectal cancer cells.Western blot analysis and immunofluorescence showed that the expression of G6 PD and PKM2 proteins in HCT116,HT-29 and Caco-2 cells was higher than that of FHC cells(P<0.05).The activity of hexokinase(HK)in the human colon cancer cells was significantly higher than that of FHC cells(P<0.05).Conclusion:1 The expression of p16 and p21 protein was down-regulated in human colorectal cancer,and the activity of SA-?-Gal decreased,while the cell viability increased.2 The expression and activity of G6 PD,PKM2 and HK which are the key enzymes in the glycolytic pathway,significantly increased in the colorectal cancer cells.3 Human colorectal cancer cells displayed an enhanced anti-senescence activity and glycolytic metabolism.