Resveratrol Inhibits Proliferation And Migration Through SIRT1 Mediated Post-translational Modification Of PI3K/AKT/DLC1 In Hepatocellular Carcinoma Cells

Hepatocellular carcinoma is one of the most common malignancy in the world and its mortality is higher in China.Chemotherapy is the main therapy in the treatment of malignant tumors.However,the widely used chemotherapeutic drugs have limited efficacy and toxicity.With development of phytochemistry,more and more researchers pay their attention to the importance of herbal plants.Resveratrol is a natural polyphenolic phytoalexin,which widely found in plants.Resveratrol has many biological and pharmaceutical properties,including anti-inflammatory,antioxidant,anti-aging,neuroprotective and antitumorigenic capabilities.Here we aimed to examine effects of resveratrol and its underlying mechanism on hepatocellular carcinoma(HCC)cell lines Hep G2,Bel-7402 and SMMC-7721.Cell proliferation ability was detected by Ed U assay,we found that resveratrol inhibited proliferation of HCC cells while had a slight effect on non-tumorigenic cell line HL-7702.Apoptosis is a spontaneous process that controlled by gene.In the tumor cells,not only the cell proliferation is out of control,the apoptotic ability is also imbalance,and the induction of apoptosis is one of the mechanisms of many anti-tumor drugs.TUNEL assay was assessed whether anti-proliferative effects of resveratrol against HCC cells are mediated via apoptosis.Results showed that resveratrol increased apoptosis from 4±0.83% to 13±1.32%,3±0.78% to 14±0.72%,5±0.33% to 16±1.12% in HepG2,Bel-7402 and SMMC-7721 cells.Resveratrol induced apoptosis through up-regulation of Bax and cleaved-PARP,and down-regulation of Bcl-2,caspase-3,caspase-7 and PARP.PI3K/AKT signaling pathway is well defined and is directly associated with cell growth,proliferation and survival,constitutive activation of AKT is frequently observed in various cancers.Resveratrol acts as a suppressor of PI3K/AKT pathway by decreased the expression of p-PI3 K,p-AKT and p-FoxO3 a.SIRT1 played an importanted role in tumorigenesis,as a SIRT1 activator,resveratrol elevated SIRT1 protein expression and its enzyme activity.In order to explore the relationship of SIRT1 and PI3K/AKT signaling pathway,SIRT1 inhibitor EX527 was used to evaluate the underlying mechanism.Data showed that when SIRT1 enzymatic activity was inhibited by EX527,the phosphorylation levels of PI3 K and AKT had increased.This demonstrated that resveratrol inhibited PI3K/AKT pathway by SIRT1 activation.Tumor suppressor gene DLC1 is frequently inactivated due to genomic deletion in human hepatocellular carcinoma.Its RhoGTP domain plays important role in regulation of avariety of cellular processes including cell proliferation,gene expression,cytoskeletal organization,cell adhesion to extracellular matrix(ECM),and have been implicated in oncogenic transformation and cancer progression.The post-translational modification of DLC1 also could regulated the anti-tumorigenic function.Accompanying inhibition of cancer cell migration,protein level of DLC1 was up-regulated and its phosphorylation was enhanced by AKT with resveratrol treatment.Future work are warrant to clarify how DLC1 regulated by its domains and phosphorylation as well as precise downstream mechanisms through post-translational modification of DLC1 acts as a tumor suppressor.These findings suggest that resveratrol activated SIRT1 to induce liver cancer cell apoptosis and to inhibit migration through SIRT1 mediated post-translational regulation of PI3K/AKT signaling and phosphorylation level of FoxO3 a and DLC1 and deacetylation of FoxO1 leading to tumor suppression in HCC cells.