The Expression Of Glucose Regulated Protein 78 And Its Significance In Resistance To VP-16 In NCI-H460 Cell Line

Objective:In this study we are the first to investigate the expression of GRP78 under the induction of A23187 and its significance in the resistance to anti-tumor drugs VP-16 in a human lung cancer NCI-H460 cell line.Methods:RT-PCR and Western Blotting were used in analyzing the expression of GRP78 at mRNA and protein levels in NCI-H460 cell line induced by A23187 at different concentration (0,1,2,4, 6μM ). Cell survival to VP-16 was determined by a colony- formation assay.Results:The expression of GRP78 at both mRNA and protein levels were increased obviously in NCI-H460 cell line induced by A23187, and A23187's treatment caused a dose-dependent increase in GRP78 expression to a great degree. However, the elevation of GRP78 at protein level did not always correspond with that at mRNA level. Firstly, The starting induced concentration for GRP78 at mRNA level and protein level is 1μM and 2μM respectively. Second, 4μM of A23187 is the most for the induction of GRP78 at mRNA level, which means an around 4 folds elevation compared to the control, whereas, for GRP78 at protein level, 6μM is the most, which means a 2 folds elevation compared to the control. Commonly, the induction of GRP78 at mRNA level is easier than that at protein level. The IC₅₀ to VP-16 for the cells under the induction of A23187 (from 2μM to 4μM ) are higher than the control. Furthermore, it showed a dose-responsive trait. Based on the trend of the changes of IC₅₀ and the expression of GRP78 in different disposed cells, we conclude GRP78 is associate with resistance to VP-16.and this resistance is dependent on the level of GRP78 in NCI-H460 cell line to a great degree.Conclusions:A23187 treatment is highly effective in the induction of GRP78 and subsequent development of resistance to VP-16 in human lung...