THE EFFECT OF MICROCRYSTALLINE CHITOSAN ON THE ACTIVITY OF PYRUVATE KINASE M2 ISOENZYME INVOLVED IN REGULATING PROLIFERATION OF EHRLICH ASCITES TUMOR (EAT) CELLS IN VITRO
Journal Title: Progress on Chemistry and Application of Chitin and its Derivatives - Year 2009, Vol 0, Issue
Abstract
The pyruvate kinase M2 isoenzyme from the nucleoplasm of tumor cells, which catalyzes the reaction of the phosphoryl group transfer from 2-phosphoenolpyruvate (2-PEP) to ADP with the formation of ATP, also demonstrates the activity of histone kinase, transferring the phosphoryl group from 2-PEP to the e-amine residue of histone H1 lysine. L-cysteine triggers a change in the conformation of the bi-functional PK M2 isoenzyme from the form, which synthesizes ATP to the form responsible for H1 histone phosphorylation in the course of DNA structure relaxation. The level of nitrogen oxide (NO) produced in the EAT tumor cells was twofold lower as compared to that characteristic of the normal mouse mammary epithelial (CRL 1636) cells. In the presence of microcrystalline chitosan, there occurred a considerable increase of the NO level in the EAT cells and we observed inhibition of tumor cell proliferation. In the presence of L-NAME, a non-specific NO synthase inhibitor, there was noted a slight inhibition of the CRL 1636 cell proliferation. An increase in the level of NO in tumor cells contributed to formation of L-nitrosocysteine (L-CSN). A drop in the level of L-cysteine in consequence of its nitrosylation contributed to inhibiting the activity of histone kinase of the PK M2 isoenzyme. Decreased phosphorylation of H1 histone, a potent inhibitor of proliferation, might contribute to inhibition of proliferation of the EAT cells incubated with microcrystalline chitosan.
Authors and Affiliations
Jan Ignacak, Joanna Dulińska-Litewka, Iwona Pałka, Maria Wiśniewska-Wrona, Antoni Niekraszewicz
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