There is strong evidence that
tyrosine kinases are involved in the regulation of cellular growth and
tumor progression. Over-expressions of
tyrosine kinases have been documented in a number of
neoplasms. To study the roles of
tyrosine kinases in
colon cancer, we developed a
tyrosine-kinase-expression profile for each of the four different stages of colon
carcinogenesis, using normal colon mucosa,
adenomatous polyps, primary
carcinoma and hepatic
metastases collected from the same patient. We identified 30
tyrosine kinases expressed in these tissues: they include 10 non-
receptor tyrosine kinases (yes, fyn, lyn, brk, abl, arg, jak1, jak3, tyk2 and itk), 17
receptor tyrosine kinases (erbB2, PDGF-Ralpha, PDGF-Rbeta, kit, c-fms, met, ron, FGF-R1, FGF-R2, FGF-R3, FGF-R4, cek5, tie-1, tkt, axl, sky and Ins-R), 2 dual
kinases (mek and sek) and one possible novel
kinase. Among these
kinases, arg
kinase appears to be expressed at a higher level in primary
carcinoma and metastatic
tumor than in adjacent normal mucosa or
adenomatous polyp. This result was confirmed by extensive analysis of 50 additional matched sets of normal colon and colon-
tumor specimens, using arg-specific primers and RT-PCR reactions. This study identifies a possible role for
arg tyrosine kinase in colon
carcinogenesis, especially in the transition from
adenoma to
carcinoma.