Molecular Medicine in Practice The Association of PI3 Kinase Signaling and Chemoresistance in Advanced Ovarian Cancer

Evidence that the phosphoinositide 3-kinase (PI3K) pathway is deregulated in ovarian cancer is largely based on the analysis of surgical specimens sampled at diagnosis and may not reflect the biology of advanced ovarian cancer. We aimed to investigate PI3K signaling in cancer cells isolated from patients with advanced ovarian cancer.Ascites sampleswere analyzed from88patients, ofwhom61 received further treatment.Cancer cells were immunomagnetically separated from ascites, and the signaling output of the PI3K pathway was studied by quantifying p-AKT, p-p70S6K, and p-GSK3b by ELISA. Relevant oncogenes, such as PIK3CA and AKT, were sequenced by PCR-amplifiedmass spectroscopy detectionmethods. In addition,PIK3CA andAKT2 amplifications and PTEN deletions were analyzed by FISH. p-p70S6K levels were significantly higher in cells from37 of 61 patientswhodid not respond to subsequent chemotherapy (0.7184 vs. 0.3496;P1⁄4 0.0100), and this difference was greater in patients who had not received previous chemotherapy. PIK3CA and AKTmutations were present in 5% and 0% of samples, respectively. Amplification of PIK3CA andAKT2 and deletion of PTEN was seen in 10%, 10%, and 27% of samples, respectively. Mutations of PIK3CA and amplification of PIK3CA/ AKT2 or deletion of PTEN did not correlate with levels of p-AKT, p-p70S6K, and p-GSK3b. In patients with advanced ovarian cancer, there is an association between levels of p-p70S6K and response to subsequent chemotherapy. There is no clear evidence that this is driven specifically by PIK3CA or AKT mutations or by amplifications or deletion of PTEN. Mol Cancer Ther; 11(7); 1–9. 2012 AACR.