Purpose: This study evaluates the effect of dual PI3K and mTOR inhibition using NVP-BEZ235 in preclinical models of ovarian cancer as a potential novel therapeutic strategy. Experimental Design: Inhibition of PI3K/Akt/mTOR signaling by NVP-BEZ235 was demonstrated by immunoblotting. The effect on cell proliferation was assessed in eighteen ovarian cancer cell lines, including four pairs of syngeneic cisplatin-sensitive and cisplatin-resistant cell lines. The in vivo effects of NVP-BEZ235 on established tumor growth were evaluated using an immunocompetent, transgenic murine ovarian cancer model (LSL-K-rasG12D/+PtenloxP/loxP). Results: NVP-BEZ235 decreased cell proliferation in all ovarian cancer cell lines assayed and sensitized cisplatin-resistant cells to the cytotoxic effects of cisplatin. Cell lines with PI3K activating mutations or Pten deletions were significantly more sensitive to the effect of NVP-BEZ235 than cell lines without these mutations (p < 0.05). A statistically significant correlation was found between relative levels of p4E-BP1 and the IC50 for NVP-BEZ235. In LSL-K-rasG12D/+PtenloxP/loxP mice with established intraperitoneal tumor disease, oral administration of NVP-BEZ235 decreased pAkt, p4E-BP1 and Ki67 in tumor tissue, and resulted in significantly longer survival compared to control animals (p < 0.05). NVP-BEZ235 also induced cell cycle arrest, caspase 3 activity, and reduced cell migration. Conclusions: Targeting PI3K and mTOR simultaneously using NVP-BEZ235 effectively inhibits ovarian cancer cell growth even in the presence of platinum resistance and prolongs survival of mice with intra-abdominal ovarian tumor disease. We propose that dual PI3K and mTOR inhibition using NVP-BEZ235 may be an effective novel therapeutic approach in patients with ovarian cancer.
- Received August 25, 2010.
- Revision received December 27, 2010.
- Accepted January 7, 2011.
- Copyright © 2011, American Association for Cancer Research.