PURPOSE: We performed experiments to investigate the change in cellular signaling that occurs during the transformation of a normal cell to a cell capable of cancerous growth, and we did so by using the NIH 3T3 cells that were transformed by transfection with the v-Ha-ras oncogene. MATERIALS AND METHODS: Parental and v-Ha-ras transfected NIH 3T3 cells were chosen as test systems. The siRNA transfections were performed using Lipofectamine 2000. The cell proliferation reagent WST-1 was used for the quantitative determination of cellular proliferation. Immunoblot analysis was performed using the ECL-Plus chemiluminescent system and a KODAK Image Station 4000R. RESULTS: The v-Ha-ras-transformed cells were found to be significantly more resistant to PP2 treatment, which is a potent inhibitor of the Src family tyrosine kinases, than were the parental cells at earlier times after treatment. However, PP2 induced growth arrest and the senescence-like phenotypes in both cell lines after longer treatment. Furthermore, the Raf-1 kinase of the v-Ha-ras-transformed cells was not affected by the expressed level of Sprouty proteins, which are negative regulators of the MAPK pathway, as evidenced by the failure of siRNA-mediated knockdown of Spry4 to activate Raf-1 kinase. Dephostatin (a tyrosine phosphatase inhibitor) effectively inhibited the proliferation of the v-Ha-ras transformed cells, whereas dephostatin had only a small effect on the parental cells' proliferation. This implied an inhibitory role for tyrosine phosphatase that is specific to the signaling pathway in the v-Ha-ras transformed cells. CONCLUSION: Taken together, our results show that the sustained activation of the oncogenic pathways through their resistance to negative feedback regulation might contribute to the transformation of NIH 3T3 cells.
Cell Line ; Cell Proliferation ; Genes, ras ; Humans ; Hydroquinones ; Lipids ; NIH 3T3 Cells ; Parents ; Phenotype ; Proteins ; Proto-Oncogene Proteins c-raf ; RNA, Small Interfering ; src-Family Kinases ; Transfection ; Tyrosine

Primary venous thrombosis caused by deficiency or qualitative abnormality of antithrombin III, protein C and protein S is usually inherited as an autosomal dominant trait. Usually, deep vein thrombosis or pulmonary thromboembolism is developed by such abnormalities, however, mesenteric vein thrombosis is rarely reported. A 27-year-old man with previous history of deep vein thrombosis underwent segmental resection of jejunum due to mesenteric vein thrombosis complicated by necrosis of jejunum. Postoperative investigation disclosed combined deficiency of antithrombin III and protein C. His son also showed deficiency of antithrombin III. Postoperatively, he is on life-long warfarin therapy without experiencing recurrence of venous thrombosis.
Adult ; Antithrombin III* ; Humans ; Jejunum ; Mesenteric Veins ; Necrosis ; Protein C* ; Protein S ; Pulmonary Embolism ; Recurrence ; Thrombosis ; Venous Thrombosis* ; Warfarin