A possible novel src-related tyrosine kinase in cancer cells of LEC rats that develop hepatocellular carcinoma.
OBJECTIVE
Src-related protein tyrosine kinase is known to be related to cell transformation. In this study, we report a possible novel src-related tyrosine kinase of 100 kDa specifically expressed in the nuclei of hepatocytes and/or cancer cells in Long-Evans Cinnamon rats, one of the experimental models of hepatocellular carcinoma.


METHODS
Src-related protein tyrosine kinase in hepatocytes of Long-Evans Cinnamon rats was analyzed by using immunohistochemistry and Western blot and in vitro tyrosine kinase assay using a specific antibody (src antibody) against a synthetic peptide corresponding to the conserved autophosphorylation site of src family tyrosine kinases.


RESULTS
Src-related protein was found to be expressed in the nuclei of hepatocytes and/or cancer cells in Long-Evans Cinnamon rat liver, exhibiting tyrosine kinase activity, and migrated to the position of 100 kDa. The protein quantity and activity of this 100-kDa src-related protein tyrosine kinase significantly increased with the progress of chronic hepatitis to hepatocellular carcinoma, especially in the tumorous portion of the liver. On the other hand, the 100-kDa src-protein tyrosine kinase was not observed in the nuclei of hepatocytes and/or cancer cells in normal age-matched control Wistar rats.


CONCLUSIONS
Since the src-family tyrosine kinases have been observed at a molecular weight of 55 to 62 kDa and located in the hepatocellular membrane and/or cytoplasm, the 100-kDa src-related protein tyrosine kinase observed in the present study may be novel, and closely related to the pre-cancerous and cancerous process in Long-Evans Cinnamon rat liver.
Masaki
T
T
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Tokuda
M
M
Shiratori
Y
Y
Shirai
M
M
Matsumoto
K
K
Nishioka
M
M
Omata
M
M
D000818:Animals; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000473:pathology; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000201:enzymology; D007124:Immunoenzyme Techniques; D008099:Liver / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000201:enzymology* / Q000473:pathology; D051381:Rats; D020332:Rats, Inbred LEC; D017208:Rats, Wistar; D013047:Specific Pathogen-Free Organisms; D019061:src-Family Kinases / Q000276:immunology / Q000378:metabolism*
D019061:src-Family Kinases