Perifosine inhibits growth of human experimental endometrial cancers by blockade of AKT phosphorylation

Objective: Perifosine is an orally active alkylphospholipid analog, which has shown anti-tumor activity in a variety of cancers by inhibition of AKT phosphorylation. The objective of the current study was to evaluate its efficacy in in vitro models of human endometrial cancer. Study design: The effect of 10 mu M and 40 mu M perifosine on AKT phophorylation in human endometrial cancer cell lines Ishikawa and HEC 1A was determined by Western blotting. To screen for a putative antitumor effect, HEC 1A and Ishikawa cells were incubated with increasing concentrations of perifosine for 24 h, 48 h and 72 h and the number of viable cells was determined by crystal violet staining. Also the effect of a combined treatment with cisplatin and perifosine was investigated in Ishikawa cells. Flow cytometric analysis of DNA content was used to determine the effect of perifosine on the cell cycle distribution of HEC 1A and Ishikawa cells and to assess potential toxic side effects of perifosine on peripheral blood lymphocytes (PBL). Results: AKT phosphorylation was dose-dependently inhibited by perifosine. Concomitantly, perifosine displayed anti-tumor activity in both cell lines at concentrations that showed no effect on peripheral blood lymphocytes. Growth inhibitory effects became more pronounced with increasing treatment time. While IC 50 values at 24 h were >40 mu M, IC 50 values after 48 h were approximately 7 mu M in Ishikawa and 25 mu M in HEC 1A cells. After 72 h, the IC 50 was below 1.25 mu M for Ishikawa and about 6 mu M for HEC 1A cells. Perifosine cotreatment substantially increased cytotoxic effects of cisplatin in human Ishikawa endometrial cancer cells. Of note, the anti-tumor activity of perifosine was not confined to a specific phase of the cell cycle. Conclusions: The small molecule AKT inhibitor perifosine showed substantial anti-tumor activity in human endometrial cancer cell lines. Since these effects were increased with cisplatin, perifosine seems to be a good candidate for treatment combinations with classical cytostatic compounds. Thus, perifosine should be further evaluated in clinical studies in endometrial cancer. (C) 2008 Elsevier Ireland Ltd. All rights reserved.