p53/p21(CIP1) cooperate in enforcing rapamycin-induced G(1) arrest and determine the cellular response to rapamycin.

摘要: The relationship between G(1) checkpoint function and rapamycininduced apoptosis was examined using two human rhabdomyosarcoma cell lines, Rh1 Rh30, that express mutated p53 alleles. Serum-starved tumor cells became apoptotic when exposed to rapamycin, but were completely protected by expression of a rapamycin-resistant mutant mTOR. Exposure rapamycin (100 ng/ml) for 24 h significantly increased the proportion Rh30 in phase, although there no significant changes cyclins D1, E, or A drug-treated cells. To determine whether associated with continued slow progression through S h, then labeled bromodeoxyuridine (BrdUrd). Histochemical analysis showed >90% morphological signs had incorporated BRDURD: restoration arrest could protect from rapamycin-induced apoptosis, infected replication-defective adenovirus expressing either p21(CIP1). Infection Ad-p53 Ad-p21, not control virus (Ad-beta-gal), induced accumulation, up-regulation p21(CIP1), complete protection apoptosis. Within infection cyclin reduced >90%. Similar results obtained after Consistent these data, incorporation [(3)H]thymidine BrdUrd into DNA inhibited, as cyclin-dependent kinase 2 activity. These data indicate is consequence during mTOR inhibition arresting overexpression protects against response next wild-type murine embryo fibroblasts nullizygous p53or Under serum-free conditions, rapamycin-treated MEFs increase compared controls. In contrast, deficient ( approximately 2.4-fold) p21(CIP1) 5.5-fold). p53(-/-) Ad-p21 serum-containing inhibited more (MEFs) than those lacking When added almost 90% 70% respectively, nucleoside. only 19% presence rapamycin. Western blot levels little effect on D1 E any MEF strain. However, very low cells, remained high Taken together, suggest cooperates enforcing cycle arrest, leading cytostatic MEFs, having this agent may be