Inactivation of PTEN is associated with a low p27Kip1 protein expression in breast carcinoma

Shinichi Tsutsui, Hiroshi Inoue, Kazuhiro Yasuda, Kosuke Suzuki, Kouichirou Tahara, Hidefumi Higashi, Shoichi Era, Masaki Mori

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


BACKGROUND. It was previously demonstrated that PTEN protein expression is reduced in 67 of 236 (28%) breast carcinomas. Recent experimental studies suggested that the cell cycle inhibitor p27Kip1 (p27) is a downstream mediator through which PTEN negatively regulates cell cycle progression. METHODS. The immunohistochemic expression of p27 and PTEN protein expression was evaluated in a series of 228 invasive ductal carcinomas of the breast. RESULTS. PTEN protein expression was found to have decreased in 65 of 228 (29%) cases, while the nuclear accumulation of p27 protein was low in 99 of 228 (43%) cases. A reduced PTEN protein expression correlated significantly (P = 0.0214) with a low p27 protein expression. Univariate analysis indicated that the patients demonstrating a combined decrease in PTEN and p27 protein expression have a significantly (P = 0.0044) worse disease-free survival (DFS) than those with other combinations of these two protein expression patterns, while multivariate analysis indicated that the lymph node status, MIB-1 counts, and the combination of PTEN/p27 protein expression (P = 0.0452) are independently significant prognostic factors for DFS. CONCLUSIONS. A reduced PTEN protein expression correlated significantly with a low p27 protein expression in breast carcinoma. The finding that the patients with a combined decrease in both protein expressions had a poor prognosis thus suggests that a combined loss of PTEN and p27 function is associated with an aggressive phenotype in breast carcinoma.

Original languageEnglish
Pages (from-to)2048-2053
Number of pages6
Issue number10
Publication statusPublished - Nov 15 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


Dive into the research topics of 'Inactivation of PTEN is associated with a low p27Kip1 protein expression in breast carcinoma'. Together they form a unique fingerprint.

Cite this