Human SBK1 is dysregulated in multiple cancers and promotes survival of ovary cancer SK-OV-3 cells.

Protein kinases are involved in comprehensive cellular processes and also implicated in many human diseases. SH3-binding domain kinase 1 (SBK1) was first cloned and characterized in rat and the human cDNA was cloned in our lab in 2006, but the expression and function of endogenous protein have not been well studied in human. In this follow up study, we screened a panel of cell lines and tissues, as well as a tumor tissue array for SBK1 expression at both RNA and protein levels. To detect the protein, we generated the first rabbit polyclonal antibody against human SBK1. We show that the SBK1 is expressed in most of the cells and tissues examined, and the protein is highly up-regulated in ovarian serous adenocarcinoma while down-regulated in esophagus squamous cell carcinoma and stomach adenocarcinoma. When over-expressed in an ovarian cancer cells SK-OV-3 by adenovirus infection, SBK1 protected the cells from apoptosis induced by the viral infection, therefore promoting cancer cell survival. Given that a missense mutation K92E in human SBK1 was identified recently from ovarian mucinous carcinoma, together, these results suggest that the wide-spread expression pattern of human SBK1 may predict a broad cellular function, and its dysregulated in certain cancers suggests an involvement of the protein in the pathogenesis of human cancers.