1997 Volume 51 Issue 1 Pages 8-11
Nine src family members are known to date: C-src, C-yes, C-lck, C-fyn, C-hck, C-lyn, C-blk, C-fgr and C-yrk. They are protooncogene product and encode proteins of molecular weights of 55 to 62 kilodaltons (kDa), which are non-receptor type, membrane associated and protein tyrosine kinases (PTK). There is a close correlation between elevated activities of src family tyrosine kinases activity and cell transformation. We elucidated the involvement of src-related protein tyrosine kinases in the development of hepatocellular carcinoma in the LEC rat, the strain genetically destined to develop this cancer. In this study, we found a novel tyrosine kinase of 100 kDa specifically expressed in the nuclei of hepatocytes and/or cancer cells of LEC rat liver, by means of Western blot and immunohistochemistry. In addition, no 100 kDa src-PTK in the nuclei of cancer cells was obsreved in human HCC. Furthermore, we found that the protein level of this 100 kDa src-related PTK was significantly increased with the development of HCC. These findings suggest that this 100 kDa src-related PTK might be closely associated with the malignant transformation of LEC rat liver.
