Abstract 4122: C-Met inhibition sensitivity in vitro: Autocrine vs. paracrine activation of the c-Met pathway

Abstract

Abstract Tumor cells frequently harbor abnormalities in signaling pathways, leading to increased migration, invasion, survival, angiogenesis, and proliferation. C-Met is one such commonly aberrant pathway. C-Met is a receptor tyrosine kinase critical for embryogenesis and liver repair, and protein levels are often elevated in a large variety of tumors. C-Met is activated by the endogenous ligand Hepatocyte Growth Factor (HGF). HGF is produced by mesenchymal cells and stimulates the c-Met protein, leading to a variety of downstream signaling pathways that result in increased migration, proliferation, survival, and angiogenesis. While many tumor cells express the c-Met receptor, a number of tumor types, including glioblastoma and osteosarcoma, have been observed to co-express both HGF and c-Met, and activate the pathway in an autocrine manner. The purpose of the current study was to determine whether tumor cells utilizing autocrine c-Met signaling would more sensitive to c-Met inhibition than those relying on the paracrine pathway. Experimental procedures include ELISA, western, migration, invasion, and clonogenic cell survival. Cell lines investigated include: two glioblastoma cell lines (U87 and U118), two osteosarcoma cell lines (OS156 and OS521), two fibrosarcoma cell lines (KHT and RIF), a breast (MDA-MB-231) and a prostate cancer cell line (PC-3). The small molecule c-Met inhibitor BMS-777607 and an HGF-neutralizing antibody were used to compare the effects interrupting the c-Met axis in these tumor cell lines. Data obtained using ELISA of conditioned media show that the glioblastoma (U87 and U118) and fibrosarcoma (KHT) cells secrete HGF, while the breast and prostate cells (MDA-MB-231; PC-3) do not. Furthermore western blot analysis showed higher basal levels of phospho-c-Met among the HGF-secreting cell lines in comparison to the non-HGF secreting cell lines, indicating that the KHT, U87, and U118 models activate c-Met in an autocrine manner, while the MDA-MB-231 and PC-3 lines activate c-Met in a paracrine manner. Importantly preliminary assessments indicate the autocrine glioblastoma and fibrosarcoma cell lines to be more sensitive to small molecule c-Met inhibition than the paracrine breast and prostate cancer cell lines. Investigations of additional cancer models are ongoing but our findings to date support the notion that cancer cells that autocrine activate the c-Met pathway may more susceptible to c-Met inhibition than those utilizing primarily paracrine activation of this pathway. Citation Format: Veronica Hughes, Dietmar W. Siemann. C-Met inhibition sensitivity in vitro: Autocrine vs. paracrine activation of the c-Met pathway. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4122. doi:10.1158/1538-7445.AM2015-4122