Analysis of Signal Transduction Pathway of Syk in Breast Cancer Cells-as a comparison with that of Her2

点击翻译按钮获取中文摘要

Breast cancer is one of the most popular cancers in women. Protein-tyrosine kinases have been shown to be involved in the pathogenesis of breast cancer. Her2 is a protein-tyrosine kinase which is believed to have oncogenic function, whereas Syk is another protein-tyrosine kinase which displays oncostatic potential. We have attempted to compare these two kinases focusing on their expression and their down stream signaling system. We estimated the expression of these kinases using immunoblotting in human breast cancer cell lines. In some of these cell lines, one breast cancer cell line, MDAMB453 expressed Her2 but no Syk. When Syk is introduced in MDAMB453, the expression of Her2 declined according to the expression level of Syk. The growth rate of Syk-introduced MDAMB453 clones was decreased as compared to that of mock cells. In MDAMB453 clones, administration of adriamycin induced an increase in Syk expression, which was correlated with a degradation of polyADP-ribose polymerase, a substrate of caspases. These data imply a mechanism of the opposite functions of these kinases in breast cancer carcionogenesis, in which Syk enhances apoptosis upon an exposure to cancer therapeutics.