| Objectives:Fatty acid synthase(FASN)catalysing the terminal steps in the de novo biogenesis of fatty acids are correlated with low survival and high disease recurrence in bladder cancer patients.Pyruvate kinase M2(PKM2)regulates the final step of glycolysisits levels and provides a growth advantage to tumors.However,it is unclear whether changes in PKM2 affects FASN and its mechanism;This thesis will uncover the molecular mechanisms that down-regulation PKM2 inhibits FASN expression,and provide a novel target and scientific foundation for treating bladder cancer.Methods:FASN and PKM2 were detected in patients with BC(n=20)and adjacent normal bladder tissue(n=10)by immunoblotting and immunostaining.Western blot(WB),qRT-PCR and IF were used to detect the expression changes of PKM2 in bladder cancer cells tansfected with lenti-virus shFASN or inhibition of FASN with TVB-3166.The interaction between FASN and PKM2 was confirmed by coimmunoprecipitation assay.And its molecular mechanisms were explored by probing p-Akt,p-mTOR,and SREBP-1c levels via WB.Results:FASN and PKM2 were significantly more likely to be expressed in the malignant group than in the benign group as detected by Western blotting.Inhibition of PKM2 with Shikonin(SK)or siPKM2 resulted in down-regulation FASN expression,PKM2 inhibited the expression of sterol regulatory element binding protein 1c(SREBP1c)by inactivating the Akt/mTOR signaling pathway.This in turn suppressed the transcription of FASN,a major lipogenic gene which reduces tumor growth.Furthermore,this inhibitors combination induced a strong anti-proliferative and anti-colony forming effect and apoptosis in bladder cancer cell lines.Conclusion:Our novel findings that PKM2 is a critical regulator of FASN by binding transcription factors SREBP-1c.At the same time,down-regulating the expression of SREBP-lc by PKM2 is regulated by inactivating the AKT/mTOR pathway and further inhibiting the expression of FASN,thereby inhibiting the growth and proliferation of bladder cancer cells.These results will lay the foundation for examining the role of FASN in BC tumorigenesis and possible therapeutic targets in bladder cancer. |
