ABEMACICLIB, A CDK4/6 INHIBITOR, INHIBITS PROLIFERATION AND INDUCES CELLULAR SENESCENCE IN CHOLANGIOCARCINOMA CELLS

Abstract

Cholangiocarcinoma (CCA) is an aggressive bile duct cancer with a poor prognosis and a high mortality rate, primarily due to late diagnosis which often results in standard treatment failure. Therefore, targeted therapies offer a promising approach for CCA treatment. Our preliminary bioinformatics analyses have shown that Cyclin D and CDK4/6, key regulators of cell cycle progression, are significantly overexpressed in CCA patients, suggesting these as potential therapeutic targets. In this study, we demonstrated that Abemaciclib, an FDA-approved CDK4/6 inhibitor, effectively inhibits CCA cell proliferation. In addition to inhibiting cell proliferation, CDK4/6 inhibitors have also been demonstrated to induce senescence, a condition in which persistent senescent cancer cells may lead to unfavorable treatment outcomes, including the potential for cancer relapse. Since there is no publicly available database in CCA to analyze the association between Abemaciclib and senescence induction, we utilized a database of breast cancer cells treated with Abemaciclib. The results showed that the cellular senescence processes are associated with Abemaciclib treatment. This was further confirmed by a RT-qPCR and -galactosidase staining assay, which are markers of senescence. The results indicated an upregulation of senescence marker genes, p16 and p21, along with a significantly higher number of positively blue-stained cells in Abemaciclib-treated CCA cells compared to untreated cells. Collectively, this is the first study to evaluate the effects of Abemaciclib on cell proliferation and cellular senescence in CCA cells. These findings could contribute to the development of strategic combination therapies by combining CDK4/6 inhibitors with senolytic drugs to effectively target persistent senescent cells in a sequential manner.