Cell polarity protein CRB3 is an independent favorable prognostic factor for clear cell renal cell carcinoma.

Epithelial cells possess apical‑basal polarity and loss of epithelial cell polarity contributes to tumorigenesis and cancer progression. The Crumbs (CRB) polarity protein plays a crucial role in epithelial polarity maintenance, apical membrane formation, and tissue morphogenesis. Although evidence is increasing on involvement of deregulated polarity proteins in cancers, little is currently known about the roles of the CRB (Drosophila), especially the roles of CRB3, a homolog of the CRB, in clear cell renal cell carcinoma (ccRCC). Studies have shown that CRB3 may act as a tumor suppressor in non‑human mammalian cells; the study here was aimed to examine the expression status of CRB3 in ccRCC and the relationships between CRB3 expression and clinicopathologic parameters of ccRCC patients. Our results showed that CRB3 was weakly expressed in ccRCC tissues, but strongly expressed in adjacent normal kidney tissues. Patients with loss of CRB3 expression showed a significantly shorter overall survival (OS) than patients with positive CRB3 expression. Our results suggested that CRB3 may be an independent favorable prognostic factor for patients with ccRCC. We also found that overexpression of CRB3 restrained invasion and migration of 786‑O cells and loss of CRB3 expression promoted invasion and migration of human embryonic kidney 293T (HEK 293T) cells. This finding may explain why the negative CRB3 expression was associated with poor prognosis in human ccRCC. Altogether, our data demonstrated that CRB3 may be used as a new independent favorable prognostic factor for human ccRCC.