Exogenous Expression of hRFI Induces Multidrug Resistance through Escape from Apoptosis in Colorectal Cancer Cells

Abstract

Background: hRFI is a newly discovered gene encoding a Ring Finger domain highly homologous to that of the X-chromosome-linked inhibitor of apoptosis protein, which is among the most potent inhibitors of apoptosis. The hRFI protein is preferentially expressed in colorectal cancers, although its actual function is unknown. The aim of this study was to determine whether hRFI possesses an anti-apoptotic function in colorectal cancer cells against chemotherapeutic agents. Materials and Methods: HCT116 colorectal cancer cells were exogenously transfected with hRFI or LacZ as a control. After exposure to either cisplatin, irinotecan or 5-fluorouracil, apoptosis and caspase-3 activity were evaluated by flow cytometry analysis. Results: The hRFI transfectant exhibited significant resistance to apoptosis induced by each of the three agents, along with inactivation of caspase-3. Growth in the normal medium was not altered. Conclusion: hRFI plays an important role in the resistance to chemotherapeutic agent-induced apoptosis in colorectal cancer cells.