Synergistic antitumor effect between Olaparib and Chidamide by regulation of MYBL2 in lung cancer.

Recently, various basic research and clinical studies have revealed the further potential of poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor Olaparib and histone deacetylase inhibitor Chidamide in lung cancer. However, no research available was found to report whether there is a synergistic effect of Olaparib in combination with Chidamide. This research was conducted to investigate whether there is a synergistic effect between the two drugs and the underlying mechanism in lung cancer cell lines. Here, we treat lung cancer cell lines with Olaparib with or without Chidamide in vivo and in vitro. Based on that, we found that there were synergistic effects between Olaparib and Chidamide. Combined use of them cooperatively downregulated the expression of MYBL2, which was responsible for the downregulation of BRCA1, a main member of DNA damage repair. Simultaneously, Olaparib-induced inhibition of PARP expression leads to the 'synthetic lethality' of cells. On the other hand, MYBL2 may regulate the expression of cycle protein dependent kinase 1, causing G2M cell cycle arrest. Consequently, the combination of Olaparib and Chidamide synergistically induces cell apoptosis through synthetic lethality and cell cycle arrest to exert an antitumor effect.