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


CONCLUSIONS
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.
Wang
Qi
Q
Department of Respiratory Medicine, The Second Hospital Affiliated to Dalian Medical University, Dalian 116023, China. wqdl@263.net
Wang
Tao
T
Wang
Yingyan
Y
Wang
Wei
W
Wang
Yanyan
Y
Hu
Xiujuan
X
Shao
Shujuan
S
Zhang
Jinhui
J
Suo
Zhenhe
Z
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D000091342:Endoplasmic Reticulum Chaperone BiP; D005047:Etoposide / Q000494:pharmacology*; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
D000972:Antineoplastic Agents, Phytogenic; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D000001:Calcimycin; D005047:Etoposide