Decreased phosphoactive ERKs and JNKs in Malachite-green-transformed Syrian hamster embryo fibroblasts are associated with increased phosphoactive p38 kinase: possible therapeutic importance

BACKGROUND: Malachite green (MG), consisting of green crystals with a metallic lustre, is highly soluble in water, cytotoxic to various mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and possible exposure of human beings, MG poses a potential environmental health hazard. We have earlier reported the malignant transformation of Syrian hamster embryo (SHE) cells by MG. METHODS: Cell transformation assays were carried out as described in the literature. Western blotting and flow cytometry were carried out by standard methods. RESULTS: In this study, we have studied the role of all three isoforms of mitogen-activated protein (MAP) kinases, i.e. extracellular regulated kinases (ERKs), Jun N-terminal kinases (JNKs) and p38 kinase in the MG-transformed SHE fibroblasts compared to controls. Our results showed that transformed cells were associated with decreased expression of ERKs and JNKs as evidenced by Western blotting studies. However, the p38 MAP kinase was found to be upregulated. Flow cytometric DNA histogram analysis indicated an increase in the expression of S phase cells in the transformed cell line as compared to their control counterparts. CONCLUSIONS: The present studies indicate that decreased phosphoactive ERKs and JNKs and increased phosphoactive p38 kinase are associated with increased S phase cells during transformation of SHE cells by MG.