Investigation of cell death markers with qRT-PCR method in PrPC expression supressed H69 and H69AR cell lines

Cellular Prion protein (PrPC) is a cell surface protein which is expressed in early stages of embryogenesis. PrPC, is the most expressed protein in the central nervous system cells and lymphoid tissues and it's involved in many roles. However, many of its functions have not yet been fully elucidated. On the other hand, studies have shown that PrPC is expressed at a high level in cancer cells, and suggests, that it plays a role in cell survival and multidrug resistance (MDR) mechanisms. PrPC has become a centre of interest due to its functions in cancer cells and has become a potential target for new therapeutic approaches due to its role in programmed cell death and multi drug resistance mechanisms. The purpose of this study is to determine the interactions between PrPC expression and programmed cell death in small cell lung carcinoma (SCLC) cell line (H69) an its MDR phenotype (H69AR). To determine the roles of PrPC in programmed cell death and multidrug resistance mechanisms, four groups have been designed in both of two cell lines including control, PrPC siRNA treated group, Doxorubicin treated group and PrPC siRNA+Doxorubicin treated group, and the expression levels of Prnp, Bax, Becn1 and CD44 were observed with qRT-PCR (quantitative Real Time Polymerase Chain Reaction) method. Increased expression of CD44 were observed as a result of the suppression of PrPC with siRNA in the H69 cell line (p<0,05). In the H69AR cell line, the increase in the expression of Becn1 and CD44 were observed in the PrPC siRNA treated group, as well as the expression of Prnp in the Doxorubicin treated group increased significantly (p<0,05). However, no significant change was detected in Prnp levels in the groups PrPC siRNA and PrPC siRNA+Doxorubicin (p>0,05). Our findings suggest that Prnp expression is associated with CD44 in the H69 cell line and it's significantly related to autophagy and drug resistance in the H69AR cell line. In conclusion we propose that, in the small cell lung cancers with the MDR phenotype, concurrent treatment with chemotherapy and Prnp downregulation will be an effective treatment method.