Abstract
Pten-/- cells display a partially defective checkpoint in response to ionizing radiation (IR). The checkpoint defect was traced to the ability of AKT to phosphorylate CHK1 at serine 280, since a nonphosphorylated mutant of CHK1 (S280A) complemented the checkpoint defect and restored CDC25A degradation. CHK1 phosphorylation at serine 280 led to covalent binding of 1 to 2 molecules of ubiquitin and cytoplasmic CHK1 localization. Primary breast carcinomas lacking PTEN expression and having elevated AKT phosphorylation had increased cytoplasmic CHK1 and displayed aneuploidy (p < 0.005). We conclude that loss of PTEN and subsequent activation of AKT impair CHK1 through phosphorylation, ubiquitination, and reduced nuclear localization to promote genomic instability in tumor cells.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 193-204 |
| Number of pages | 12 |
| Journal | Cancer Cell |
| Volume | 7 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2005 |
ASJC Scopus subject areas
- Oncology
- Cancer Research
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