Abstract 444: Hyaluronan-mediated motility receptor (RHAMM) in ovarian cancer

Abstract

Abstract This study focuses on Hyaluronan Mediated Motility Receptor (RHAMM) protein expression in ovarian carcinoma (OC). RHAMM protein increases migration, invasion and is associated with poor prognosis when overexpressed. It is a dualistic oncogenic protein located within and on the cell surface acting as a receptor for Hyaluronan (HA). RHAMM is not generally overexpressed in normal tissues, but is upregulated in a number of cancers and is associated with poor clinical outcome. However, the role of RHAMM in OC progression is unknown. Hypothesis: Elevated RHAMM levels promote OC progression and represent a novel urinary biomarker for OC. Procedures: Measuring RHAMM expression in OC cell protein lysate and conditioned media (CM) was done by western blot (WB) and densitometry. With institution approval, patient cohort urine from male and female healthy controls and patients with cancer of the ovary, lung, breast, prostate, cervix, colorectum, skin, endometrium, head and neck, and brain were acquired from the H. Lee Moffit Cancer Center at the University of South Florida. Enzyme-linked immunosorbent assay (ELISA) designed for RHAMM detection, was used to measure patient urine expression levels. Results: Cultured OC cells overexpress and secrete RHAMM. Using OC, SV-40 large T-antigen transfected human ovarian surface epithelial (IOSE) cells (HIO118, IOSE-121) and human dermal fibroblasts (HDF), we found >2x the expression of RHAMM protein in BC (MCF7) and OC (OVCAR5, OV2008, C13) cells by WB. WB of CM indicated >3x RHAMM levels secreted by OC compared to IOSE cells. Urinary levels of RHAMM are elevated in OC patients. Since RHAMM is not an integral membrane protein, but rather loosely tethered to the plasma membrane, we determined whether RHAMM could be detected in bodily fluids of OC patients. ELISA showed detection of urinary RHAMM protein levels averaged 0.140 ng/ml (n = 26) in healthy patient controls whereas OC patients averaged 0.411 ng/ml (n = 132). Conclusions: Prior to this study, overexpression and secretion of RHAMM by OC cells had not been reported. This has expanded our knowledge of OC etiology by delineating a functional role for RHAMM-driven OC progression. Validating elevated urinary levels of RHAMM suggests it is a potential diagnostic marker alone or in combination with other markers for OC detection. Further, the ability to monitor OC through the course of disease using urinary RHAMM levels could indicate recurrent disease or therapeutic efficacy. Understanding RHAMM expression in OC may lead to a possible diagnostic/prognostic indicator or therapeutic target for OC. Citation Format: Stephanie Buttermore, Patricia Kruk. Hyaluronan-mediated motility receptor (RHAMM) in ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 444.