Abstract 742: Antitumor activity of Trametinib, a MEK1/2 inhibitor, in malignant pleural mesothelioma cells in vitro

Abstract

Abstract Introducion: Malignant pleural mesothelioma (MPM) is a highly aggressive malignancy and there is no approved targeted therapy. The MAPK pathway plays critical roles in the regulation of cell proliferation, growth, differentiation, and survival in multiple solid tumors, including MPM. Trametinib, a selective MEK inhibitor, have a survival benefit in patients with V600 BRAF-mutant metastatic melanoma. FDA approved Trametinib for these patients in May 2013. The effect of Trametinib in MPM cells has not been well studied. Purpose: We examined the effects of Trametinib in MPM cells in vitro. Methods: To examine the effect of Trametinib on the proliferation of MPM cells, we performed cell proliferation assay using four MPM cell lines, NCI-H2452, NCI-H226, NCI-H2052 and MSTO-211H. To examine the effect of Trametinib on intracellular signaling, we performed Western blot analysis in NCI-H226 cell line. Results: Trametinib exhibited potent antiproliferative activity in all four MPM cell lines with IC50 values ranging from 0.5 μM to 44 μM. Trametinib blocked the phosphorylation of ERK until 72 hours and decreased the expression of CD44 in a dose-dependent manner. In addition, the expression of CD44 was inhibited (48-72 hours) after the suppression of ERK phosphorylation by Trametinib. Conclusions: Our results suggest that Trametinib is a promising therapeutic agent for MPM. Citation Format: Hiroyuki Cho, Seiji Matsumoto, Yoshiko Fujita, Ayumi Kuroda, Masaki Hashimoto, Teruhisa Takuwa, Toshi Menju, Makoto Sonobe, Nobuyuki Kondo, Hiroshi Date, Seiki Hasegawa. Antitumor activity of Trametinib, a MEK1/2 inhibitor, in malignant pleural mesothelioma cells in vitro. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 742. doi:10.1158/1538-7445.AM2014-742