사람 결장암 세포주인 HCT15에서 Protein kinase C에 의한 다약제 내성 조절
Regulation of multidrug resistance by protein kinase C in human colon cancer HCT15 cell
단백질 결장암 세포주;
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Multidrug resistance (MDR) is the phenomenon in which cells becomes resistant to several classes of structurally and functionally diverse drugs after exposure to a single cytotoxic agent. Acquisition of multigrug resistance phenotype in tumor cells is a major obstacle to successful therapy. ATP-binding cassette (ABC) transporters are a family of transporter proteins that contribute to drug resistance via ATP-dependent drug efflux pump. Two prominent members of the ATP-binding cassette superfamily of transmembrane proteins, P-glycoprotein and multidrug resistance associated protein encoded by mdr1 and mrp1 gene, can mediate the cellular extrusion of xenobiotics and anticancer drugs from tumor cells. Expression pattern of mdr1 gene in human colon cancer HCT15 cells were investigated by using transcription polymerase chain reaction (RT-PCR). The HCT15/ADR selected for resistance to doxorubicin (adriamycin;ADR) expressed mdrl gene and showed resistance to doxorubicin-induced cell death. In HCT15 cells, the cytotoxity of doxorubicin was associated with concentration-dependent cleavages of PARP (Poly ADP-ribose polymerase) and Lamin B, a hallmark of apoptosis. Two-dimentional electrophoretic patterns in HCT15 and HCT15/ADR cell lines showed difference in the amount of calreticulin. Calreticulin is a very good substrate for protein kinase C (PKC) isoenzymes and bind to activated PKC isoenzymes. Western blot of PKC isoenzymes revealed the PKC-α was strikingly increased in HCT15/ADR cells. In addition, increased activity of PKC-α was confirmed in the membrane of HCT15/ADR cells. Inhibition of PKC-α by Go6976 in HCT15/ADR cells caused time-dependent downregulation of MDR1 expression and induced apoptosis by doxorubicin. These results suggest that increased expression and activity of PKC-α isoform is closely associated with regulation of MDR phenotype in human colon cancer HCT15/ADR cells.