PDF file - 1622K, Figure S1.Combinaion of DHT and NVP-BEZ235 induced synergistic effect of growth inhibition in MCF cells growth. Figure S2. Combination of DHT and NVP-BEZ235 exposure affects expression of markers of epithelial to mesenchymal transitions (EMT) in MCF-7 cells. Figure S3. DHT did not inhibit AR-negative breast cancer cell growth. HCC1395 (AR-/ER+) and MDA-MB-231 (AR-/ER-) cells were treated with control, DHT, NVP-BEZ235 or DHT/BEZ235 combination for 5 days. Figure S4. Combination of DHT and NVP-BEZ235 achieved better therapeutic effects in breast cancer xenografts compared to either single agent. Figure S5. Tumors from mouse MCF-7 xenografts were dissected and subjected to immunohistochemistry for the shown proteins. Figure S6. DHT suppressed low level NVP-BEZ235-induced MYC expression and AKT phosphorylation in breast cancer. Figure S7. DHT decreased the known side effects of NVP-BEZ235 treatment.
ARTICLE ABSTRACTNVP-BEZ235 is a newly developed dual PI3K/mTOR inhibitor, being tested in multiple clinical trials, including breast cancer. NVP-BEZ235 selectively induces cell growth inhibition in a subset, but not all, breast cancer cell lines. However, it remains a challenge to distinguish between sensitive and resistant tumors, particularly in the pretreatment setting. Here, we used ten breast cancer cell lines to compare NVP-BEZ235 sensitivity and in the context of androgen receptor (AR) activation during NVP-BEZ235 treatment. We also used female SCID mice bearing breast tumor xenografts to investigate the beneficial effect of dihydrotestosterone/NVP-BEZ235 combination treatment compared with each alone. We found that AR-positive breast cancer cell lines are much more sensitive to NVP-BEZ235 compared with AR-negative cells, regardless of PTEN or PI3KCA status. Reintroducing AR expression in NVP-BEZ235 nonresponsive AR-negative cells restored the response. DHT/NVP-BEZ235 combination not only resulted in a more significant growth inhibition than either drug alone, but also achieved tumor regression and complete responses for AR+/ER+ tumors. This beneficial effect was mediated by dihydrotestosterone (DHT)-induced PTEN and KLLN expression. Furthermore, DHT could also reverse NVP-BEZ235–induced side effects such as skin rash and weight loss. Our data suggest that AR expression may be an independent predictive biomarker for response to NVP-BEZ235. AR induction could add benefit during NVP-BEZ235 treatment in patients, especially with AR+/ER+ breast carcinomas. Mol Cancer Ther; 13(2); 517–27. ©2013 AACR.