Abstract
BACKGROUND AND OBJECTIVE: GRP75, a member of HSPs which is overexpressed in some resistant cancer cells, is a molecular chaperone mainly located in mitochondrial membrane. The aim of this study is to investigate the role of GRP75 on the resistant mechanisms of cancer cells by downregulating GRP75 expreesion via RNAi approach. METHODS: Cisplatin-resistant cell A549/CDDP was established from their parental human lung adenocarcinoma cell line A549 by combining gradually increasing concentrations of cisplatin with high dosage impact. The shRNA for GRP75 was transfected into A549 and A549/CDDP cells by lentivirus. Western blot and methyl thiazolyl tetrazolium (MTT) assay were applied to detect the influence of silencing GRP75 expression on sensitivity of the cells to cisplatin. RESULTS: The infection rate of six groups were all over 90%. After infection, the level of expression of GRP75 in both A549 and A549/CDDP were down-regulated (P < 0.05); the level of expression of p53 in A549/CDDP was up-regulated (P < 0.05) and the level of expression of bcl-2 of A549/CDDP was down-regulated (P < 0.05). The resistance index of A549/CDDP before and after infection were 21.52 and 4.14 respectively. CONCLUSIONS: Cisplatin resistance of lung cancer cells is associated with overexpression of GRP75 gene, which could regulate the expressions of p53 and bcl-2.