AIM To examine the influence on apoptotic mechanisms following inhibition of polo-like kinases as therapeuticallyapproach for cholangiocellular cancer treatment. METHODS As most cholangiocarcinomas are chemotherapyresistant due to mechanisms preventing tumor cell death, we investigated the effect of Cisplatin on cholangiocellular carcinoma(CCA) cell lines KMCH-1 and Mz-Ch-1. Polo-like kinases(PLK) are important regulators of the cell cycle and their inhibition is discussed as a potential therapy while PLK inhibition can regulate apoptotic mediators. Here, cells were treated with PLK inhibitor BI6727(Volasertib), Cisplatin, and in combination of both compounds. Cell viability was assessed by MTT; apoptosis was measured by DAPI staining and caspase-3/-7 assay. Western blot and q RT-PCR were used to measure expression levels of apoptosis-related molecules Bax and Bcl-2. RESULTS The cell viability in the CCA cell lines KMCH-1 and Mz-Ch-1 was reduced in all treatment conditions compared to vehicle-treated cells. Co-treatment with BI6727 and cisplatin could even enhance the cytotoxic effect of cisplatin single treatment. Thus, co-treatment of cisplatin with BI6727 could slightly enhance the cytotoxic effect of the cisplatin in both cell lines whereas there was evidence of increased apoptosis induction solely in Mz-Ch-1 as compared to KMCH-1. Moreover, PLK inhibition decreases protein levels of Bcl-2; an effect that can be reversed by the proteasomal degradation inhibitor MG-132. In contrast, protein levels of Bax were not found to be altered by PLK inhibition. These findings indicate that cytotoxic effects of Cisplatin in Mz-Ch-1 cells can be enhanced by co-treatment with BI6727.CONCLUSION In conclusion, BI6727 treatment can sensitize CCA cells to cisplatin-induced apoptosis with proteasomal Bcl-2 degradation as an additional pro-apoptotic effect. AIM To examine the influence on apoptotic mechanisms following inhibition of polo-like kinases as therapeutically applicable for cholangiocellular carcinoma treatment. METHODS As most cholangiocarcinomas are chemotherapy due to to mechanisms preventing tumor cell death, we investigated the effect of Cisplatin on cholangiocellular carcinoma (CCA) cell lines KMCH-1 and Mz-Ch-1. Polo-like kinases (PLK) are important regulators of the cell cycle and their inhibition is discussed as a potential therapy while PLK inhibition can regulate apoptotic mediators. Here, cells were treated with PLK inhibitor BI6727 Cell viability was assessed by MTT; and apoptosis was measured by DAPI staining and caspase-3 / -7 assay. Western blot and q RT-PCR were used to measure expression levels of apoptosis (Volasertib, Cisplatin, and in combination of both compounds. -related molecules Bax and Bcl-2. RESULTS The cell viability in the CCA cell lines KMCH-1 and Mz-Ch-1 was reduced in all treatment conditions compared to Vehicle-treated cells. Co-treatment with BI6727 and cisplatin could even even enhance the cytotoxic effect of cisplatin single treatment. Thus, co-treatment of cisplatin with BI6727 could slightly enhance the cytotoxic effect of the cisplatin in both cell lines rather there was evidence of increased apoptosis induction solely in Mz-Ch-1 as compared to KMCH-1. Furthermore, PLK inhibition decreases protein levels of Bcl-2; an effect that can be reversed by the proteasomal degradation inhibitor MG- Bax were not found to be altered by PLK inhibition. These results indicate that cytotoxic effects of Cisplatin in Mz-Ch-1 cells can be enhanced by co-treatment with BI6727.CONCLUSION In conclusion, BI6727 treatment can sensitize CCA cells to cisplatin-induced apoptosis with proteasomal Bcl-2 degradation as an additional pro-apoptotic effect.