Senolysis-Based Elimination of Chemotherapy-Induced Senescent Breast Cancer Cells by Quercetin Derivative with Blocked Hydroxy Groups

Drug-induced senescence(definition) program may be activated both in normal and cancer cells as a consequence of chemotherapeutic treatment, leading to some adverse side effects such as senescence-associated secretory phenotype (SASP), secondary senescence, and cancer promotion. Targeted elimination of senescent cells can be achieved by drugs with senolytic activity (senolytics(definition)), for example, the plant-derived natural compound quercetin, especially when co-treated with kinase inhibitor dasatinib. In the present study, three quercetin derivatives were synthesized and tested for improved senolytic action against etoposide-induced senescent human normal mammary epithelial cells and triple-negative breast cancer cells in vitro. Transformation of catechol moiety into diphenylmethylene ketal and addition of three acetyl groups to the quercetin molecule (QD3 derivative) promoted the clearance of senescent cancer cells as judged by increased apoptosis compared to etoposide-treated cells. A QD3-mediated senolytic effect was accompanied by decreased SA-beta galactosidase activity and the levels of p27, IL-1β, IL-8, and HSP70 in cancer cells. Similar effects were not observed in senescent normal cells. In conclusion, a novel senolytic agent QD3 was described as acting against etoposide-induced senescent breast cancer cells in vitro. Thus, a new one-two punch anti-cancer strategy based on combined action of a pro-senescence anti-cancer drug and a senolytic agent is proposed.