Molecular Mechanisms Of Which Period2 Regulates MDM2 Of Human Glioma Cell To Stimulate Apoptosis After X-Ray Irradiation In Vivo

Objective To investigate the mechanism of which Period2 kockdown influences apoptosis in glioma when it was exposed to X-rays.Methods the Period2-sh RNA,Control-sh RNA lentivirus of nonspecific-interference infected human U343 glioma cells of p53 wild-type in order to collate Period2 knockdown cells and Control virus cells selected by puromycin.Cells of sh RNA-Period2 、 sh RNA-Control 、 blank control group were injected subcutaneously in necks of nude mices. Until the tumors’ volume reached the standard(1000mm3), we applied 10 Gy X-ray irradiation to the three groups of gliomas, and treat this time as 0h.Mices were sarcificed and tumors were harvested at 24 h, 48 h, 72 h after irradiation respectively.The apoptosis of Period2 knockdown group were detected by TUNEL.DNA damage was analyzed by expression of phosphorylated H2 AX, and applied q RT-PCR and Western Blot to discover DNA damage repair gene ATM,,apoptosis-related genes p53, MDM2 and c-myc expression after X-ray irradiation.Results In cell experiences,Period2-sh RNA lentivirus could significantly knock down the expression of clock gene Period2 during human glioma U343 cells;, tumors of Period2 knock-down group releaved a slighter DNA damage and apoptosis than the control group after irradiation of X –ray and at 24 h, 48 h, 72 h after X-ray, Period2 knockdown group was proved that incresed in DNA damage and apoptosis;In addition,as Period2 knocked down, the expression levels of ATM was also significantly deregulated and so was p53,while c-myc increased rapidly and MDM2 did,too.Conclusion In our experiences,Period2 knockdown could inhibit the sensitivity of X-ray towards human glioma; And it could promote the role of apoptosis pathway ATM-p53-MDM2 though changes of the expression of ATM, p53, c-myc, MDM2,then stimulated the apoptosis in U343 gliomas.