Rapamycin and p53 act on different pathways to induce G1 arrest in mammalian cells.

Published

Journal Article

Certain growth regulatory kinases contain a common domain related to the phospho-inositol 3 (PI-3) kinase catalytic site. These include the ATM gene product, DNA-PKcs, and the target of rapamycin (TOR in yeast; and FRAP in mammalian cells). Rapamycin inhibits growth factor signalling and induces G1 arrest in many cell types. Some growth regulatory PI-3 kinases appear functionally linked to p53 and we have explored potential links between cellular effects induced by rapamycin and p53. In p53 null cells rapamycin inhibited cell cycling but did not induce G1 arrest. In cells which showed selective G1 arrest in response to rapamycin, rapamycin had no effect on basal levels of p53 protein. Similarly p21(WAF1) protein was not induced by rapamycin. The kinetics of the cellular p53/p21(WAF1) response to ionising radiation was unaffected by rapamycin; and the ability of growth factor to protect against p53-mediated apoptosis in response to DNA damage was also unaffected by rapamycin. The ATM gene is mutated in the cancer susceptibility syndrome ataxia telangiectasia (AT) but such mutant cells showed a similar sensitivity to rapamycin compared to their normal counterparts. RKO cell lines of common genetic background, but with different levels of functional p53 protein, also responded similarly to rapamycin. Thus, although rapamycin and p53 are each able to induce G1 arrest, they appear to act through independent growth regulatory pathways.

Full Text

Duke Authors

Cited Authors

  • Metcalfe, SM; Canman, CE; Milner, J; Morris, RE; Goldman, S; Kastan, MB

Published Date

  • October 1997

Published In

Volume / Issue

  • 15 / 14

Start / End Page

  • 1635 - 1642

PubMed ID

  • 9349496

Pubmed Central ID

  • 9349496

Electronic International Standard Serial Number (EISSN)

  • 1476-5594

International Standard Serial Number (ISSN)

  • 0950-9232

Digital Object Identifier (DOI)

  • 10.1038/sj.onc.1201341

Language

  • eng