azd-6244 and Adenocarcinoma--Clear-Cell

Topics: Adenocarcinoma, Clear Cell; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzimidazoles; Benzoxazoles; Biomarkers, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Synergism; Female; Gene Expression Regulation, Neoplastic; Humans; Indazoles; Mice; Mice, Nude; Morpholines; Ovarian Neoplasms; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Pyrimidines; Sulfonamides; TOR Serine-Threonine Kinases; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Clear cell carcinoma (CCC) of the ovary tends to show resistance to standard chemotherapy, which results in poor survival for patients with CCC. Developing a novel therapeutic strategy is imperative to improve patient prognosis. Epidermal growth factor receptor (EGFR) is frequently expressed in epithelial ovarian cancer. One of the major downstream targets of the EGFR signaling cascade is extracellular signal-related kinase (ERK). PEA-15, a 15-kDa phosphoprotein, can sequester ERK in the cytoplasm. MEK1/2 plays a central role in integrating mitogenic signals into the ERK pathway. We tested the hypothesis that inhibition of the EGFR-ERK pathway suppresses tumorigenicity in CCC, and we investigated the role of PEA-15 in ERK-targeted therapy in CCC. We screened a panel of 4 CCC cell lines (RMG-I, SMOV-2, OVTOKO, and KOC-7c) and observed that the EGFR tyrosine kinase inhibitor erlotinib inhibited cell proliferation of EGFR-overexpressing CCC cell lines through partial dependence on the MEK/ERK pathway. Furthermore, erlotinib-sensitive cell lines were also sensitive to the MEK inhibitor selumetinib (AZD6244), which is under clinical development. Knockdown of PEA-15 expression resulted in reversal of selumetinib-sensitive cells to resistant cells, implying that PEA-15 contributes to selumetinib sensitivity. Both selumetinib and erlotinib significantly suppressed tumor growth (P < 0.0001) in a CCC xenograft model. However, selumetinib was better tolerated; erlotinib-treated mice exhibited significant toxic effects (marked weight loss and severe skin peeling) at high doses. Our findings indicate that the MEK-ERK pathway is a potential target for EGFR-overexpressing CCC and indicate that selumetinib and erlotinib are worth exploring as therapeutic agents for CCC.

Topics: Adenocarcinoma, Clear Cell; Animals; Apoptosis Regulatory Proteins; Benzimidazoles; Blotting, Western; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; ErbB Receptors; Erlotinib Hydrochloride; Female; G1 Phase; Humans; Intracellular Signaling Peptides and Proteins; MAP Kinase Kinase 1; MAP Kinase Kinase 2; MAP Kinase Signaling System; Mice; Mice, Nude; Ovarian Neoplasms; Phosphoproteins; Protein Kinase Inhibitors; Quinazolines; RNA Interference; Tumor Burden; Xenograft Model Antitumor Assays