Expression of KITENIN, a KAI1/CD82 binding protein and metastasis enhancer, in bladder cancer cell lines: Relationship to KAI1/CD82 levels and invasive behaviour

KITENIN is a newly identified binding partner of the KAI1/CD82 metastasis suppressor. Recent studies using a mouse model of colon cancer, have suggested that KITENIN might be a metastasis enhancer whose functions are modulated by an interaction with KAI1/CD82. To begin exploration of the possible importance of KITENIN to human cancer, we examined KITENIN mRNA (by RT-PCR) and protein expression (by Western blotting) in a large series of bladder cancer cell lines, and then compared these levels to the expression of KAI1/CD82 and of previously determined in vitro invasive behaviour of these same cancer cell lines. We report that KITENIN was uniformly expressed in all cancer cell lines, but those lines in which KAI1/CD82 was not detected, had a higher in vitro invasive ability and altered actin organisation (as determined by fluorescence microscopy), than those lines in which KAI1/CD82 was present. Our data suggest that the relationship between KITENIN and KAI1/CD82 may be an important determinant of tumour cell behaviour.