Abstract POSTER-BIOL-1305: Lovastatin decreases macrophage IL-6 and CXCL1 production in an ovarian tam-like model reducing ovarian cancer cell invasion
Authors: Bradaric Michael J , Litchfield Lacey , Johnson Alyssa , Habis Mohammed , Ismail Nadia , Lengyel Ernst , Romero Iris 
Published: August 2015

Introduction: Accumulating epidemiologic evidence suggests that cancer patients taking statins for elevated cholesterol and have improved cancer survival. In vitro studies have also shown that invasion, proliferation and cell growth are inhibited by statin treatment in several cancer cell lines. Here, we report that lovastatin inhibits of ovarian cancer cell proliferation and invasion towards ovarian tumor associated macrophages (TAM).

Methods: Ovarian cancer cells (ID8, HeyA8, SKOV3ip1, and OVCAR5) were grown to confluency and treated with varying dosages of lovastatin (10 - 40 uM). Proliferation was measured using an MTT assay at 24, 48, and 72 hours after treatment in both complete DMEM media. Invasion was measured as the average number of cancer cells that invaded collagen (I)-coated wells. Lovastatin (20 uM for 16 hours) greatly reduced invasion of all ovarian cancer cell types. THP-1 macrophages were exposed to serum-free media from ovarian cancer cells to induce a pro-tumor phenotype. After 24 hours, the ability of the conditioned macrophages to induce both human and murine ovarian cancer cell invasion was assessed. A chemokine array was performed on media from macrophages to determine which chemokines were altered during the transformation from naïve to a TAM-like phenotype, and what effect lovastatin had on those chemokines. The results of the array was confirmed with ELISA for candidate markers.

Results: Lovastatin produced a dose-dependent decrease in cell proliferation in HeyA8, OVCAR5, SKOV3ip1 and ID8 cancer cell lines. Lovastatin inhibited OVCAR5, HeyA8, and SKOV3ip1 cell invasion with exposure to 20 uM concentrations for 24 hours before and during an overnight invasion assay. When macrophages (THP-1) were incubated in ovarian cancer cell conditioned media, more invasion of HeyA8 cancer cells was observed compared to either non-stimulated (naïve) macrophages or HeyA8 conditioned media alone; indicating that it was the presence of macrophages with conditioned media that stimulated invasion. Invasion of cancer cells towards the stimulated macrophages was significantly reduced when the macrophages were treated with low-dose lovastatin (10 uM for 16 hours). To understand the mechanisms by which stimulated macrophages promote cancer cell invasion chemokine arrays were performed. The results showed that IL-6 and CXCL1 were up regulated during TAM transformation and reduced with lovastatin therapy. The results observed with regard to IL-6 were confirmed in an ELISA where lovastatin treatment produced a dose-dependent reduction in IL-6 production.

Discussion: Our studies demonstrate two possible mechanisms by which lovastatin might have a protective effect in ovarian cancer: a) by reducing cancer cell proliferation and b) by interrupting cancer cell invasion promoted by tumor associated macrophages. The second finding is particularly provocative as the primary site of OvCa metastasis is the omentum, a site rich in macrophages that may be facilitating tumor seeding and growth. This study raisers the question of whether statins could be repurposed as a cancer therapeutic targeting the tumor-promoting effects of macrophages in the tumor microenvironment.

Citation Format: Michael J Bradaric, PhD; Lacey Litchfield, PhD; Alyssa Johnson, BS; Mohammed Habis, MD; Nadia Ismail, BS; Ernst Lengyel, MD, PhD; Iris Romero, MD. Lovastatin decreases macrophage IL-6 and CXCL1 production in an ovarian tam-like model reducing ovarian cancer cell invasion [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-BIOL-1305.