Overexpression Of The Clock Gene Per2 Promotes Oral Squamous Cell Carcinoma Progression By Inhibiting Autophagy Via The PI3K/AKT/mTOR Pathway

Background: Current studies have found that Per2 was decreased in a variety of human cancers and plays an important tumor suppressor role.However,the biological functions and regulatory mechanism of Per2 in oral squamous cell carcinoma(OSCC)remain unknown.Objection: To investigate the influence and regulatory mechanism of Per2 on cell proliferation,apoptosis and autophagy in OSCC,and validate the biological functions in vitro and in vivo.Methods: Through constructing Per2 overexpression and knockdown lentivirus,OSCC cells with stable overexpression or silence of Per2 were separately established.The protein expression of PIK3 CA,AKT,p-AKT,mTOR,p-mTOR,LC3 B,P62 and Beclin1 were detected by western blotting.CCK8 assay and Flow cytometry were performed to evaluate cell proliferation.Cell apoptosis was detected by TUNEL assay and Flow cytometry.Cell autophagy was examined using transmission electron microscope.Per2 overexpression OSCC cells was used in tumorigenicityassay,tumor weight,volume and growth rate were tested,and LC3 B,P62mRNA expression in tumors was detected.Results: We discovered that the expression of Per2 was decreased in OSCC cells.Overexpression of Per2 promoted apoptosis and autophagy of OSCC cells and prohibited proliferation.In Per2-overexpressing OSCC cells,the expression levels of PIK3 CA,p-AKT,p-mTOR,p62 and Beclin1 were significantly reduced,and LC3 B II / I ratio was significantly increased.In contrast,in Per2-silenced OSCC cells,the results in Per2-silenced OSCC cells was opposite.When an AKT activator SC79 was added to Per2-overexpressing OSCC cells,the increased autophagy,apoptosis and decreased proliferation were significantly restored.Furthermore,when Per2-overexpressing OSCC cells was treated with Autophinib,an autophagy inhibitor,the decreased proliferation and increased apoptosis were significantly rescued.In vivo tumorigenisis assay also confirmed that overexpression of Per2 suppresses the growth of OSCC.Conclusion: Our research results demonstrate that Per2 suppresses OSCC progression by motivating autophagy,as well as inhibiting cell proliferation and promoting apoptosis,which were mediated by autophagy,in a PI3K/AKT/mTOR pathway-dependent manner.Per2 could potentially be used as a valuable prognostic marker and therapeutic target for OSCC.