Mechanistic Study On The Suppression Of Ovarian Cancer Cell Growth By Proguanil In Combination With Olaparib

Objective: Olaparib is a PARP inhibitor with significant clinical activity in patients with BRCA1/2 mutant ovarian cancer.Proguanil,a kind of biguanides,has been demonstrated that has the strongest tumour growth inhibitory effect,including metformin.This research explore the effects of olaparib and proguanil alone or in combination on the proliferation,migration and apoptosis of ovarian cancer cells and their mechanisms of action,aimed to develop a potential medical option for treating ovarian cancer patients.Methods: The ovarian cancer cell lines,OVCAR-3 and SKOV-3were treated by olaparib and proguanil alone or in combination.We examined the effect on proliferation by MTT and colony formation assays.On the basis of the results of the MTT assay,CI values were calculated using Compu Syn software according to the Chou-Talay method to test the synergistic effect of two drugs.While cell migration was measured by the transwell assay.The effect on apoptosis was measured by flow cytometry and AO/EB staining assays.Western blotting was used to detect the protein expression levels of Bcl-2,Bax,p-ATM,γH2AX and BRCA1 in cells treated with olaparib and/or proguanil.Results: Both proguanil and olaparib individually suppressed ovarian cancer cells’ proliferation,migration,and induced apoptosis.When the two agents were combined,they exerted a stronger synergistic inhibition of ovarian cancer cells’ proliferation and migration,and induced more apoptosis.At the protein level,both drugs activated the pro-apoptotic Bax protein and inhibited the anti-apoptotic Bcl-2 protein,and the combination of the two drugs could promote apoptosis more markedly.Meanwhile,proguanil enhanced the olaparib-induced increases in p-ATM protein andγH2AX protein expression,and decreases in BRCA1 protein expression.Conclusion: Proguanil in combination with olaparib synergistically inhibited the proliferation and migration,and promotes apoptosis of ovarian cancer cells.Proguanil enhanced olaparib-induced DNA damage and reduced the efficiency of DNA homologous recombination repair.