Background: Sprouty (Spry) proteins, modulators of receptor tyrosine kinase signaling pathways1 , have been shown to be deregulated in a variety of pathological conditions including cancer2. Here, we investigated the expression of Spry1, Spry2 and Spry4 isoforms in a panel of human ovarian cancer cell lines.
Methods: Seven human ovarian cancer cell lines OVCAR-3, SKOV-3, 1A9, CAOV-3, A2780, OV-90 and IGROV-1, and one primary human ovarian surface epithelial cell line HOSEpiC were employed to investigate protein expression by western blotting. RT-PCR was performed on the extracted RNA to evaluate the expression of Spry at mRNA level. Subcellular distribution of Spry proteins was examined by immunofluorescence microscopy and immunohistochemical staining using specific antibodies.
Results: Our western blot analysis showed nonuniform patterns of Spry expression in the cancer cells, none of which conformed to the pattern observed in the normal ovarian epithelial cells employed as control. Among the seven cancer cell lines studied, Spry1 was expressed lower in four cell lines and higher in one as compared with the control. As for Spry2, four cell lines showed lower and two exhibited higher expression. Spry4 was expressed by all cell lines, among which OVCAR-3 and SKOV-3 had the highest and lowest levels of the expression, respectively. Other cell lines showed almost similar amount of Spry4 expression. Results from RT-PCR assay raised the possibility that Spry protein levels may not necessarily correspond with its expression at mRNA level. Our immunostaining study revealed that Spry2 was predominantly distributed within the whole cytoplasm in vesicular structures whereas Spry1 was found in both the cytoplasm and nucleus.
Conclusion: Collectively, our study unveiled the differential expression of Spry proteins in various ovarian cancer cell lines. This might provide clues to further investigation of Spry mode of action and/or function.