Decreased expression of c-Src in human transitional cell carcinoma

Src, a membrane-associated nonreceptor tyrosine kinase, belongs to the Src family kinase group (SFK). Dysregulation and excessive activity of Src has been reported in multiple human cancers. Src plays a critical role in many aspects of tumor development including the proliferation, survival, adhesion, invasion, and migration in multiple tumor types. Additionally, Src also plays a role in regulating the microenvironment of the cancers, and promotes the angiogenic signaling pathway for angiogenesis. However, the expression of Src in human transitional cell carcinoma is still unclear. In the current study, we demonstrated the expression level of c-Src in the human transitional cell carcinoma tissue array and compared it with normal urothelial tissues. Surprisingly, c-Src is greatly expressed in the normal urothelial tissues. However, decreasing expression of c-Src is observed in a grade-dependent manner. This finding is also confirmed in human bladder cancer cell lines. This observation shed light on a new opportunity to elucidate the pathways and biologic functions of c-Src involved in tumorigenesis, progression and prognosis of human transitional cell carcinoma. Moreover, Src inhibitors should be used with caution in cancer therapeutics to treat human transitional cell carcinoma.