A preliminary study on the synthetic lethal effect of berberine and olaparib on pancreatic cancer cells and its mechanism

Pancreatic cancer is a kind of malignant tumor with high mortality rate. Early operation and late chemoradiotherapy are the treatment criteria, but the prognosis is still poor. Berberine, an alkaloid compound present in many herbal plants, is capable of inducing oxidative DNA damage and downregulating homologous recombination repair (HRR) in cancer cells. Poly (ADP ribose) polymerase-1 (PARP-1) is a sensor of DNA damage with key roles in DNA repair. In this study, we demonstrated that berberine and PARP inhibitor olaparib have a synthetic lethal effect on pancreatic cancer cells. The expression level of RAD51 were reduced by berberine. Correspondingly, PARP became hyperactivated in response to berberine treatment. When berberine is combined with olaparib, the expression of Rad51 and Parp are inhibited. The combination of berberine and olaparib synergistically inhibit cell activity and induce cell apoptosis. In addition, the synergistic effect of berberine and olaparib can be reversed by apoptosis inhibitor and necrosis inhibitor. Together, the results indicate that berberine combined with olaparib have a synthetic lethal effect on pancreatic cancer cells.