sirolimus and Cystadenoma--Serous

Uterine serous carcinomas (USC) harbor simultaneous HER2 (ERBB2) over-expression and gain of function mutations in PIK3CA. These concurrent alterations may uncouple single agent anti-HER2 therapeutic efficacy making inhibition of the mammalian target of rapamycin (mTOR) a promising option to heighten anti-tumor response.. Both in vitro and in vivo experiments were conducted to assess proliferation, cell death and anti-tumor activity of ridaforolimus, lapatinib and combination lapatinib, trastuzumab (L/T) and ridaforolimus. With institutional approval, NOD/SCID mice bearing xenografts of non-immortalized, HER2 gene amplified cell lines (ARK1, ARK2) with and without PIK3CA gene mutations were divided into four arm cohorts. Ridaforolimus was administered alone and in combination with L/T. Tumor volumes were assessed and posttreatment analysis was performed.. We observed dose dependent in vitro abrogation of downstream target proteins including phospho-AKT and phospho-S6. In both in vivo models, single agent ridaforolimus impaired xenograft tumor growth. Combination ridaforolimus and L/T, however, further improved the observed anti-tumor activity only in the ARK1 model with the PIK3CA gene mutation (E542K). The addition of mTOR inhibition to dual HER2 blockade added no additional anti-tumor effects in the ARK2 xenografts. Western blot and immunohistochemical analysis of downstream pathway alterations following in vivo treatment revealed dual HER2 blockade with ridaforolimus was necessary to induce apoptosis, decrease proliferation and abrogate phospho-S6 protein expression in the PIK3CA mutated model.. These pilot data suggest that PIK3CA gene mutation may be an effective biomarker for selecting those HER2 over-expressing USC tumors most likely to benefit from mTOR inhibition.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzoxazoles; Cell Cycle; Cell Proliferation; Class I Phosphatidylinositol 3-Kinases; Cystadenoma, Serous; Drug Synergism; Female; Gene Amplification; Humans; Lapatinib; Mice; Mice, Inbred NOD; Mice, SCID; Phosphatidylinositol 3-Kinases; Pyrimidines; Quinazolines; Receptor, ErbB-2; Sirolimus; TOR Serine-Threonine Kinases; Trastuzumab; Uterine Neoplasms; Xenograft Model Antitumor Assays

Patients with clear cell carcinoma of the ovary (OCCC) have poor survival due to resistance to standard chemotherapy. OCCC has frequent activating mutations of the PIK3CA gene. The present study was conducted to clarify the efficacy of the inhibition of the PI3K-AKT-mTOR pathway in OCCC. We used 8 OCCC cell lines and 5 ovarian serous adenocarcinoma (OSAC) cell lines. The mutation status of the PIK3CA and KRAS genes was examined by direct sequencing. The IC50 values of NVP-BEZ235 (BEZ235) and temsirolimus were determined by WST-8 assay. Protein expression levels of PI3K-AKT-mTOR pathway molecules were examined by western blotting. Cell cycle distribution was analyzed by flow cytometry. Annexin V staining was used for detecting apoptosis. We also investigated the effects of BEZ235 on OCCC tumor growth in a nude mouse xenograft model. Four of the 8 OCCC cell lines showed a PIK3CA mutation while none of the 5 OSAC cell lines showed a mutation. The IC50 values of BEZ235 for the OCCC cell lines were lower than these values for the OSAC cell lines. The IC50 value of temsirolimus was higher than BEZ235 in the OCCC cell lines. The PIK3CA mutation was more frequently noted in OCCC than OSAC cells, but the sensitivity of these cell lines to BEZ235 or temsirolimus was not related to the mutation status. pHER3 and pAkt proteins were expressed more frequently in OCCC compared with OSAC. However, protein expression levels were distributed widely, and were not related to the sensitivity. Treatment with BEZ235 suppressed expression of pAkt, although treatment with temsirolimus did not. OCCC cells exhibited G1 phase arrest after treatment with BEZ235 and apoptosis with a higher concentration of the agent. BEZ235 significantly inhibited tumor growth in mice bearing OVISE and TU-OC-1 cell tumors. The present study indicated that the PI3K-AKT-mTOR pathway is a potential target for OCCC, and that BEZ235 warrants investigation as a therapeutic agent.

Topics: Adenocarcinoma, Clear Cell; Animals; Cell Line, Tumor; Cystadenoma, Serous; Female; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Mice; Mice, Nude; Neoplasms, Experimental; Ovarian Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Quinolines; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays