PROTEIN-TYROSINE KINASE AND PROTEIN-SERINE THREONINE KINASE EXPRESSION IN HUMAN GASTRIC-CANCER CELL-LINES/

Protein kinases play key roles in cellular functions. They are involve d in many cellular functions including; signal transduction, cell cycl e regulation, cell division, and cell differentiation. Alterations of protein kinase by gene amplification, mutation or viral factors often induce tumor formation and tumor progression toward malignancy. The id entification and cloning of kinase genes can provide a better understa nding of the mechanisms of tumorigenesis as well as diagnostic tools f or tumor staging. In this study, we have used degenerated polymerase-c hain-reaction primers according to the consensus catalytic domain moti fs to amplify protein kinase genes (protein-tyrosine kinase, PTK, and protein-serine/threonine kinase, PSK) from human stomach cancer cells. Following amplification, the protein kinase molecules expressed in th e gastric cancer cells were cloned into plasmid vectors for cloning an d sequencing. Sequence analysis of polymerase-chain-reaction. products resulted in the identification of 25 protein kinases, including two n ovel ones. Expression of several relevant PTK/PSK genes in gastric can cer cells and tissues was further substantiated by RT-PCR using gene-s pecific primers. The identification of protein kinases expressed or ac tivated in the gastric cancer cells provide the framework to understan d the oncogenic process of stomach cancer.