Disabled-2: a protein up-regulated by high molecular weight hyaluronan has both tumor suppressor and tumor promoting roles in ovarian cancer

Abstract

Abstract Objective: Although the pro-tumorigenic functions of hyaluronan (HA) are well documented in ovarian cancer, there is limited information on the effects of different molecular weight HA. The aim of this study was to analyse the effects of different molecular weight HA on ovarian cancer cells overexpressing Notch3 intracellular domain (NICD3, stem cell associated protein). Methods: Mass spectrometry analysis of spheroids from ES-2 cells overexpressing NICD3 (ES-2-Rv-NICD3) with wild type ES-2 (ES-2:ES-2-Rv-NICD3, 1:3) treated with 27kDa, 183kDa or 1000kDa HA identified a novel protein regulated by high molecular weight HA (HMW-HA), disabled-2 (DAB2). Correlations between DAB2 and patient prognosis and pro-tumorigenic signatures were assessed in online databases. DAB2 was assessed by immunohistochemistry in a tissue microarray cohort of high grade serous ovarian carcinoma (HGSOC) and matching tissues following relapse. Gain-of-function lentiviral methods were employed in A2780 and OVCAR3 ovarian cancer cells to determine the effect of DAB2 on cell survival, spheroid formation, gene expression, cell motility and invasion in vitro and in vivousing the chick chorioallantoic membrane (CAM) assay. Results: HMW-HA (1000kDa) enhanced spheroid formation of ES-2:ES-2-Rv-NICD3 cells. Mass spectrometry identified DAB2 was upregulated 5.2 fold in HMW-HA treated ES-2:ES-2-Rv-NICD3 spheroids. Online database analysis showed DAB2 was downregulated in ovarian cancer compared to normal ovarian tissue but increased in metastatic compared to primary ovarian tumors. High DAB2 expression was associated with poor patient outcome and positively correlated with EMT markers. Stromal DAB2 immunostaining was significantly increased in matched tissues at relapse compared to diagnosis and associated with reduced survival. Furthermore, DAB2 protein co-localised with macrophage marker (CD68) in HGSOC tissues. In OVCAR3 but not A2780 cells, DAB2 overexpression enhanced carboplatin resistance and reduced cell motility and invasion in vitro. DAB2 overexpression reduced OVCAR3 and A2780 cell survival and in vivoinvasion in the CAM assay. Conclusions: Our findings highlight that DAB2 has both tumor suppressive and pro-tumorigenic functions in ovarian cancer