RT Journal Article
SR Electronic
T1 Overexpression of p21<sup>waf1</sup> Decreases G<sub>2</sub>-M Arrest and Apoptosis Induced by Paclitaxel in Human Sarcoma Cells Lacking Both p53 and Functional Rb Protein
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1088
OP 1093
DO 10.1124/mol.55.6.1088
VO 55
IS 6
A1 Li, WeiWei
A1 Fan, Jianguo
A1 Banerjee, Debabrata
A1 Bertino, Joseph R.
YR 1999
UL http://molpharm.aspetjournals.org/content/55/6/1088.abstract
AB We examined the effect of overexpression of p21waf1 on cytotoxicity of paclitaxel, a microtubule stabilizer, using a tetracycline-inducible expression system in human sarcoma cells (SaOs-2) that lack both functional retinoblastoma protein and p53. Under normal growth conditions, p21waf1 is not detectable in SaOs-2 cells. Upon p21waf1 induction by tetracycline withdrawal, we observed a reduced apoptotic response to paclitaxel with a 3- to 6-fold increase in IC50 values compared with that of cells not induced by p21waf1. We also observed a 5-fold increase in the IC50 value when cytotoxicity to vincristine, another microtubule-disrupting agent, was assessed, whereas we observed a marked decrease in the IC50 value after p21waf1 induction in response to etoposide, a topoisomerase II inhibitor. After treatment with paclitaxel, less accumulation of G2-M was observed in p21waf1-induced cells compared with non-p21waf1-induced cells (57% versus 74%). p21waf1 induction also inhibited the increased cyclin B1-associated kinase activity induced by paclitaxel. Overexpression of p21waf1 in SaOs-2 cells lacking both p53 and functional retinoblastoma protein may decrease the G2-M arrest induced by paclitaxel due to suppression of the S-G2 checkpoint, resulting in a decreased apoptotic response of cells to paclitaxel.