In vivo toxicity study of N-1-sulfonylcytosine derivatives and their mechanisms of action in cervical carcinoma cell line.

New N-1-sulfonylpyrimidines showed potent growth inhibitory activity against human and mouse tumour cells of different origin. 1-(p-toluenesulfonyl)cytosine (TsC) and 1-(p-toluenesulfonyl)cytosine hydrochloride (TsC × HCl) inhibited the growth of human cervical carcinoma cells (HeLa), and had no significant cytotoxic effects on normal human foreskin fibroblasts (BJ). TsC and TsC × HCl interfered with the HeLa cell cycle progression bringing about the accumulation of G1 phase cells and the induction of apoptosis. Antiproliferative effects of TsC and TsC × HCl were additionally confirmed by investigating de novo synthesis of RNA, DNA and proteins in HeLa cells. Monitoring gene expression using DNA Chip Analysis and quantitative PCR showed that TsC × HCl affects the expression of several cell-cycle regulating genes implying that cell cycle arrest and DNA damage-induced apoptosis might account for the observed cellular effects. In vivo experiments revealed low toxicity of TsC × HCl, as demonstrated by unaltered haematological and metabolic blood parameters. In conclusion, potent antitumour efficacy and low toxicity of new compounds in comparison with the common chemotherapy drug 5-FU make them promising anticancer agents. Additional pre-clinical and clinical studies are warranted to illuminate the mode of action of these newly synthesized compounds in vivo, which would lay the groundwork for their further optimization.