|C-Cbl protein in human cancer tissues is frequently tyrosine phosphorylated in a tumor-specific manner.|
Authors: T Kamei, K Machida, Y Nimura, T Senga, I Yamada, S Yoshii, S Matsuda, M Hamaguchi
Affiliations: Department of Molecular Pathogenesis, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan.
To search for the signaling pathway relevant to the tumorigenesis in human, we examined the expression and tyrosine phosphorylation of c-cbl proto-oncogene product, c-Cbl, in various human cancer cell lines and surgical specimens. In cells derived from human cancer, we found constitutive tyrosine phosphorylation of c-Cbl protein, whereas its phosphorylation was undetectable in control ECV304 cells. Expression and tyrosine phosphorylation of c-Cbl was also examined in various surgical specimens. Thirty-six surgical specimens obtained from human tumor tissues were studied: 9 gastric carcinomas, 10 colon carcinomas, 6 renal carcinomas, 2 hepatomas, 2 brain tumors, 2 uterus tumors, 1 breast carcinoma, 1 thyroid tumor, 1 bladder tumor and 2 lung carcinomas. We found tyrosine phosphorylation of c-Cbl protein in 12 cases (33%) of these tumor tissues in a tumor-specific manner. These results suggest the importance of c-Cbl signaling in tumorigenesis in human.