ABSTRACT
AIM:To investigate the influence of signal transducer and activator of transcription 3(STAT3)on Warburg effect in the malignant transformation of WB-F344 rat hepatic oval cells.METHODS:The WB-F344 cells were treated with N-methyl-N'-nitro-N-nitrosoguanidine(MNNG)and hydrogen peroxide(H2O2)to induce the malignant trans-formation.Evaluation of the transformed cells were measured by the soft agar colony formation assay and DNA aneuploidy with flow cytometry.The levels of glucose and lactate in the culture medium of the cells were detected by chromatography. The protein levels of alpha-fetoprotein(AFP),STAT3,p-STAT3 and glucose transporter 2(GLUT2)in the cells were ex-amined by Western blot analysis.The cell proliferation were evaluated by WST-1 assay,viable cell counting,measuring the S-phase fraction(SPF)and proliferation index(PI)using the data from flow cytometry analysis,and detecting proliferating cell nuclear antigen(PCNA)protein expression by Western blot.RESULTS:Compared with the control cells,the forma-tion of colonies in soft agar(P<0.05)and DNA aneuploidy(P<0.01)were elevated in transformed cells,and the ex-pression level of AFP was also augmented(P<0.05).The increases in the level of both glucose consumption(P<0.05) and lactate production(P<0.01)show that Warburg effect was enhanced in transformed cells.Meanwhile, the protein levels of GLUT2(P<0.01)and p-STAT3(P<0.01)in transformed cells were higher than those in the control cells.The cell proliferation parameters including SPF(P<0.01),PI(P<0.01), viable cell number and PCNA expression(P<0.01)in transformed cells were also elevated as compared with the control cells.Interestingly, stattic, an inhibitor of STAT3 activation,resulted in declines in glucose consumption(P<0.05)and lactate production(P<0.01)in the trans-formed cells.In addition,compared with transformed cells,formation of colonies in soft agar(P<0.01),DNA aneuploidy (P<0.01),AFP(P<0.05), GLUT2(P<0.05), and cell proliferation parameters including SPF(P<0.01), PI (P<0.01),viable cell number(P<0.05)and PCNA expression(P<0.05)were also decreased following stattic treat-ment in transformed cells.CONCLUSION:STAT3 promotes Warburg effect and cell proliferation probably by upregula-ting GLUT2 expression in the malignant transformation of hepatic oval cells.