TY - JOUR
T1 - Etoposide (VP-16) sensitizes p53-deficient human non-small cell lung cancer cells to caspase-7-mediated apoptosis
AU - Chiu, C. C.
AU - Lin, C. H.M.Y.
AU - Fang, K.
N1 - Funding Information:
This work is supported in part by grants (NSC-92-2311-B-003-008 and NSC-93-2311-B-003-002) from the National Science Council, Executive Yen, Taiwan, the Republic of China.
PY - 2005/5
Y1 - 2005/5
N2 - Human non-small-cell-lung-cancer (NSCLC) cells of p 53-null genotype were exposed to low-dosage topoisomearse II inhibitor etoposide (VP-16). The cellular proliferation rate could be effectively inhibited by VP-16 in dose-dependent manner. The effective drug concentration for growth inhibition could be as low as 0.5 μ M and the apoptotic phenotype became evident 48 h later. In H1299 cells, VP-16-induced cytotoxic effect was demonstrated associated with apoptosis that disappeared when restored with wild-type p53. Cell cycle analysis revealed that, upon VP-16 induction, cell death began with growth arrest by accumulating cells at the G2-M phase. The cells at sub-G1 phase increased at the expense of those at G2-M transition state. To assess the regulation of cell cycle modulators, western blot analysis of H1299 cell lysates showed the release of apoptosis initiator, cytochrome c and apaf-1 hours following drug induction. The cleavage of downstream effectors, procaspase-9 and procaspase-7, but not procaspase-3, was accompanied with proteolysis of poly-(ADP-ribose) polymerase (PARP). VP-16-activated procaspase-7 cleavage was abrogated in cells with ectopically expressed p53.On the other hand, the inhibited procaspase-7 fragmentation by caspase-specific inhibitor reversed apoptotic phenotype caused by drug induction. Thus, VP-16-induced apoptotic cell death was contributed by caspase-7 activation in p 53-deficient human NSCLC cells.
AB - Human non-small-cell-lung-cancer (NSCLC) cells of p 53-null genotype were exposed to low-dosage topoisomearse II inhibitor etoposide (VP-16). The cellular proliferation rate could be effectively inhibited by VP-16 in dose-dependent manner. The effective drug concentration for growth inhibition could be as low as 0.5 μ M and the apoptotic phenotype became evident 48 h later. In H1299 cells, VP-16-induced cytotoxic effect was demonstrated associated with apoptosis that disappeared when restored with wild-type p53. Cell cycle analysis revealed that, upon VP-16 induction, cell death began with growth arrest by accumulating cells at the G2-M phase. The cells at sub-G1 phase increased at the expense of those at G2-M transition state. To assess the regulation of cell cycle modulators, western blot analysis of H1299 cell lysates showed the release of apoptosis initiator, cytochrome c and apaf-1 hours following drug induction. The cleavage of downstream effectors, procaspase-9 and procaspase-7, but not procaspase-3, was accompanied with proteolysis of poly-(ADP-ribose) polymerase (PARP). VP-16-activated procaspase-7 cleavage was abrogated in cells with ectopically expressed p53.On the other hand, the inhibited procaspase-7 fragmentation by caspase-specific inhibitor reversed apoptotic phenotype caused by drug induction. Thus, VP-16-induced apoptotic cell death was contributed by caspase-7 activation in p 53-deficient human NSCLC cells.
KW - Cell cycle and apoptosis
KW - Etoposide
KW - Human non-small-cell-lung-cancer cells
KW - VP-16
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U2 - 10.1007/s10495-005-1898-8
DO - 10.1007/s10495-005-1898-8
M3 - Article
C2 - 15909125
AN - SCOPUS:21244469091
SN - 1360-8185
VL - 10
SP - 643
EP - 650
JO - Apoptosis
JF - Apoptosis
IS - 3
ER -
