Fibulin-5 is a tumour suppressor inhibiting cell migration and invasion in ovarian cancer

Aims Fibulin-5 is an extracellular matrix (ECM) glycoprotein which has a role in the organisation and stabilisation of ECM structures and regulating cell proliferation and tumourigenesis. Here, the expression of fibulin-5 and its functional effects on the migration and invasion of ovarian cancer cells were assessed. Methods Expression of fibulin-5 was detected in 44 ovarian tumour tissues by qRT-PCR, Western blotting and immunohistochemistry. We performed cell migration and invasion assays, and cell cycle analysis in fibulin-5 transfected SKOV3 (SKOV3-FBLN5) cells and the parental SKOV3 cells. We further examined the expression of three tissue inhibitors of metalloproteinases (TIMPs) and seven matrix metalloproteinases (MMPs) by RT-PCR. Results mRNA and protein expression of fibulin-5 were down-regulated (0.05-fold and 0.1-fold) in ovarian carcinomas compared with control tissues (p < 0.01 and p = 0.022). In wound-healing and invasion assays, significantly fewer SKOV3-FBLN5 cells than SKOV3 control cells migrated and invaded (39.1%, p = 0.046 and 70%, p = 0.03, respectively), which was reversed by siRNA-treatment. Overexpression of fibulin-5 induced G2/M arrest and increased cyclin B1, CDC2 and CDC25C. Expression of TIMP-2 (0.56-fold), MMP-3 (0.43-fold) and MMP-13 (0.18-fold) was lower and MMP-9 expression (2.20-fold) was higher in SKOV3-FBLN5 cells than in control cells. Conclusions Fibulin-5 is significantly down-regulated in ovarian carcinoma and acts as a tumour suppressor by inhibiting the migration and invasion of ovarian cancer cells.