Effect Of Combined Inhibition Of PARP And AKT On Proliferation Of Ovarian Cancer Cells And Its Mechanism

[Background]Ovarian cancer is a common malignant tumor of the reproductive organs in women.The incidence rate is second only to cervical cancer and endometrial cancer.Among them,the mortality rate of ovarian epithelial cancer is the highest in gynecological tumors,which poses a great threat to women's lives.Because the ovary is small in size,located deep in the pelvic cavity,ovarian cancer usually lacks typical symptoms at the early phases,which make it difficult to detect.Once diagnosed,it is generally in the middle and late stage.At present,ovarian cancer is mainly managed by surgery,supplemented by chemotherapy.In recent years,targeted therapies aimed at inhibiting poly ADP-ribose polymerase(PARP)and vascular endothelial growth factor receptor(VEGFR)have emerged and achieved good results for some patients.Poly(ADP-ribose)ribose polymerase is widely expressed in eukaryotic cells.As a sensor for DNA single-and double-strand breaks,it is activated to repair the broken DNA strands.In the presence of DNA damage,it can catalyze the synthesis of poly ADP-ribose(PAR)on its target proteins using NAD+ as the substrate.PAR continues to recruit many DNA repair proteins.PARP 1 is highly expressed in a variety of tumors including ovarian cancer,inhibitors of PARP have been shown to inhibit the proliferation of a variety of tumor cells,and at the same time have protective effects on myocardial ischemia-reperfusion injury,traumatic brain injury and other cardiovascular and cerebrovascular systems,but there are also a large number of clinical studies showing that the efficacy of PARP1 inhibition in some cancer patients is not as expected.The serine/threonine protein kinase AKT,also known as Protein Kinase B(PKB),plays a key role in cell signaling by phosphorylating multiple transcription factors,thereby regulating cell proliferation and survival.It has been reported in the literature that functional activation of AKT is closely related to the proliferation,invasion and metastasis of cancer cells,such as in colorectal cancer,gastric cancer and breast cancer.Our study found that AKT in certain tumor cells can be activated by PARP inhibitors.[Methods]1?The levels of p-AKT in four ovarian cancer cells including A2780?HO8910?HEY?SKOV3 treated with PARP inhibitor were analysed by Western Blotting.2?The cell proliferation of the cells treated with PARP inhibitor and AKT inhibitor was analysed by colny formation assay.3?The levels of p-AKT in cells treated with PARP inhibitor and NOX1/4 inhibitor were analysed by Western Blotting.4?The levels of p-AKT in cells treated with H2O2 and NAC were analysed by Western Blotting.5?Inhibition of tumor growth by the combination of PARP inhibitor and AKT inhibitor was verified by in vivo experiments.[Results]1?PARP inhibitors were found to up-regulate the levels of p-AKT in three of the four ovarian cancer cell lines,which may explain the poor anti-cancer efficacy of PARP inhibitors in some patients.2?PARP inhibitors and AKT inhibitors have anti-tumor effects,and the combination of the two is effective than either used alone.3?NOX1/4 inhibitor can inhibit the activation of p-AKT in ovarian cancer cells,demonstrating that AKT is regulated by NOX1/4 in ovarian cancer cells.4?H2O2 activates p-AKT in ovarian cancer cells,while NAC attenuates p-AKT activation in ovarian cancer cells,demonstrating that AKT is activated by ROS.5?Through monitoring the growth of the transplanted ovarian cancer cells in nude mice,it can be seen that the combination of PARP I inhibitor and AKT inhibitor has a stronger antitumor effect,which is consistent with the in vitro results.[Conclusions]Activation of AKT by PARP inhibition can compromise the therapeutic effect of PARP inhibitors.A combination of PARP and AKT inhibitors has a better antitumor effect.