Overexpression of serine-threonine receptor kinase-associated protein in colorectal cancers.

Transforming growth factor-beta (TGF-beta) regulates many cellular processes, including cellular proliferation and differentiation. Disruption of the TGF-beta signaling pathway can lead to cancer. Serine-threonine receptor kinase-associated protein (STRAP), an inhibitor of TGF-beta signaling, is an important regulator of cell proliferation. Here, in order to investigate the roles of STRAP in colorectal carcinogenesis, the expression of the STRAP protein was investigated in 59 colonic adenomas and 123 colorectal cancers by immunohistochemistry. Upregulation of STRAP protein was observed in 30 (50.8%) of 59 adenomas and 87 (70.7%) of 123 cancers, respectively. Statistically, overexpression of STRAP protein was not associated with clinicopathological parameters and 5 year survival (P > 0.05). Interestingly, significant association was observed between STRAP and Ki-67 positivity (P < 0.05), suggesting that STRAP contributes to an increased proliferate potential of tumor cells. These results indicate that upregulation of STRAP might play a role in tumor development as an early event for colorectal cancers.