VP-16 resistance in the NCI-H460 human lung cancer cell line is significantly associated with glucose-regulated protein78 (GRP78) induction.

AIM

To investigate the relationship between the expression of glucose-regulated protein (GRP78) and resistance to VP-16 in the NCI-H460 cell line.

METHODS

RT-PCR, real-time RT-PCR and Western blotting were used in analyzing the expression of GRP78 at mRNA and protein levels in the NCI-H460 cell line induced by A23187 at different concentrations. Cell survival with VP-16 was determined using a colony-formation assay with the account of IC50.

RESULTS

The expression of GRP78 at both the mRNA and protein levels was higher in the NCI-H460 cell line induced by A23187. A23187 treatment resulted in up to 4.8-fold elevation of GRP78 mRNA and up to 3.2-fold elevation of GRP78 protein in the experimental cells compared to the controls, all in a dose-dependent manner. The IC50s for VP-16 in the cells pretreated with different concentrations of A23187 (0, 1, 2, 4 and 6 microM) were: 12.11 +/- 0.83, 12.68 +/- 1.04, 25.82 +/- 1.83, 37.46 +/- 1.89 and 45.19 +/- 2.34 microM, respectively. Compared to the control, there was a significant elevation of IC50 for VP-16 in the cells pretreated with A23187. Survival curve analysis also showed that the induction of A23187 caused a significantly longer survival for the cells subjected to VP-16 treatment (p < 0.05).

CONCLUSION

A23187 treatment is highly effective for the induction of GRP78 and subsequent development of resistance to VP-16 in the human lung cancer NCI-H460 cell line. Based on the trend of the change in IC50 and the expression of GRP78 in differently exposed cells, we conclude that the induction of GRP78 by A23187 is significantly associated with the resistance to VP-16.