Oral Presentation The Annual Scientific Meeting of the Endocrine Society of Australia and the Society for Reproductive Biology 2013

Betaglycan blocks metastatic behaviours in granulosa cell tumours by suppressing TGFβ2/NF-κB-mediated induction of MMP2 expression (#146)

Maree Bilandzic 1 , Yao Wang 1 , Jock K. Findlay 1 , Kaye L. Stenvers 1
  1. Prince Henry's Institute, Clayton, VIC, Australia

Ovarian granulosa cell tumours (GCT) frequently recur as metastatic cancers. Over 80% of patients with recurrent, metastatic GCT will die of their disease; yet mechanisms underlying GCT metastasis are not well-understood. We showed that the type III TGFβ receptor (betaglycan) is lost as GCT progress to metastasis (1). Furthermore, we showed that two metastatic human GCT cell lines, the KGN and COV434, express little betaglycan, and forced betaglycan expression blocks their migration and invasion (1). In the current study, we investigated the involvement of matrix metalloproteinases (MMPs) in betaglycan-mediated suppression of metastasis. A qRT-PCR survey of MMP gene expression established that several MMPs are expressed in human GCT (n=17), with MMP2 the most prevalent. Immunohistochemistry confirmed abundant MMP2 expression within GCT cell cytoplasm and tumour vasculature. Using Western blot, KGN cells expressed the 72 kDa pro-form of MMP2 as well as the 64 and 55 kDa active forms under basal conditions. Exogenous TGFβ2 (1 ng/ml) stimulated MMP2 expression at the mRNA and protein levels by approximately 2-fold. Chemically inhibiting the transcription factor NF-κB reduced basal and TGFβ2-induced MMP2 expression, indicating that MMP2 expression in GCT is at least partly dependent on NF-κB signalling. Furthermore, we determined that betaglycan overexpression in GCT cells strongly suppresses NF-κB reporter activity, thus significantly reducing basal and TGFβ2-induced MMP2 expression and secretion. Finally, chemical inhibition of MMP2 mimicked the betaglycan-mediated block in GCT migratory and invasive behaviours both in monolayer and non-adherent spheroid culture. These data suggest that TGFβ2 contributes to GCT metastasis by upregulating MMP2 proteolysis in an NF-κB-dependent manner and that suppression of oncogenic NFκB activity is a major component of the mechanism underlying betaglycan’s anti-metastatic activity in GCT cells. Supported by NHMRC Australia grants (338516; 494802; 441101) and the Victorian Government's Operational Infrastructure Support Program.

  1. 1) Bilandzic et al., 2009, Mol Endo, 23:539-48.