Chemical and Molecular Biological Aspects of Alkylhydrazine-Induced Carcinogenesis in Human Cells in vitro

摘要

A cation exchange HPLC technique was developed which is rapid and provides a high resolution of pyrimidine oligonulceotides, methylated purines and a methylated pyrimidine. Treatment of asynchronous cells at a low dose of 1,1-DMH 1,2-DMH or treatment of synchronized cells at a transforming dose of 1,1-DMH did not increase the methylation of purine bases. However, a dose dependent increase in incorporation of radiolabel into DNA is observed. The presence of detectable amount of phosphotriester or alkali labile alkylated bases in DNA due to methylation is tentatively ruled out since sedimentation analysis of methylated DNA in alkaline sucrose gradient did not show any single strand breaks even at concentrations as high as 5.0mM. A preliminary labelling experiment with 14C-MAMA employing a transformation dose of MAMA showed distinctive labelling of 7-MeGUA and 06-MeGua, Alkaline sucrose gradient analysis of DNA from MAMA treated cell show a dose dependent break in DNA (Fig. 5), investigations to determine whether the damage is due to formation of methylated bases or phosphotriesters is in progress.