Effects of Tobacco-Specific Carcinogen on Protein Kinase C Isoforms

Kang, Hyung Seok; Ko, Moo Sung; Park, Ki Sung; Lee, Sub; Jheon, Sang Hoon; Kwon, Oh Choon

Abstract

BACKGROUND: Cigarette smoking is the leading cause of the lung cancer. However, mechanism of action underlying the carcinogenesis in the lung still remains to be elucidated. The present study attempted to look into the carcinogenic potential of tobacco-specific nitrosamine, NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) and the effects of protein kinase C (PKC) isoforms in an immortalized human epithelial cell model. MATERIAL AND METHOD: Immortalized human epithelial cells were exposed with NNK and examined for its carcinogenic potential as measured by saturation density, soft-agar colony formation, and cell aggregation assay. The specific isoform of PKCs involved in the cellular transformation was analysed through western blot with monoclonal antibody and measured separately in cytosolic fraction and membrane fraction. RESULT: Human epithelial cells exposed with NNK showed prominent carcinogenic potential in saturation density, soft agar colony formation, and cell aggregation assay. PKC isoform analysis results are as follows: PKC-alpha showed significant translocation of protein levels from cytosolic fraction to membrane fraction, as analyzed by immunoblot. PKC-epsilon showed a dose-dependent increase of translocation. PKC-lambda was not affected by NNK treatment.
CONCLUSION
The study demonstrated that there was a certain specificity in the patterns of isoform induction following chemical carcinogen exposure. Thus, it is suggested that identification of specific isoform be a clue to find target molecules in the carcinogenesis.