Comparative studies between the effects of mitozolomide and two novel tetrazepinones PYRCL and QUINCL on NIH:OVCAR-3 cells

• Published in: Cancer chemotherapy and pharmacology Vol. 42; no. 1; pp. 59 - 67
• Main Authors: JEAN-CLAUDE, B. J, MUSTAFA, A, DAMIAN, Z, DE MARTE, J, VASILESCU, D. E, YEN, R, THAK HAK CHAN, LEYLAND-JONES, B
• Format: Journal Article
• Language: English
• Published: Berlin Springer 1998
• Subjects: Alkylation; Antineoplastic agents; Antineoplastic Agents - pharmacology; Azepines - pharmacology; Biological and medical sciences; Cell Cycle; DNA - drug effects; DNA Damage; Drug Screening Assays, Antitumor; Female; Flow Cytometry; General aspects; Guanine; Humans; Medical sciences; Nitrogen Mustard Compounds - pharmacology; Ovarian Neoplasms - drug therapy; Ovarian Neoplasms - pathology; Pharmacology. Drug treatments; Pyridines - pharmacology; Quinolines - pharmacology; Tumor Cells, Cultured; Antineoplastic agent; Mitozolomide; DNA; Cell cycle; Established cell line; Cytotoxicity; Lesion; Mechanism of action; In vitro; Tumor cell
• ISSN: 0344-5704; 1432-0843
• DOI: 10.1007/s002800050785

Cytotoxicity, reduction of macromolecule synthesis and cell cycle perturbations by two novel 3-(2-chloroethyl)-tetrazepinones, PYRCL and QUINCL were compared with those produced by the structurally related 3-(2-chloroethyl)-tetrazinone, mitozolomide, in the OVCAR-3 cell line. Macromolecule synthesis was determined by incorporation of 3H-thymidine, 3H-uridine and 3H-leucine into acid-precipitable fractions of OVCAR-3 cell extracts. Maxam-Gilbert sequencing was used to compare the DNA alkylating sites induced by the tetrazepinones, with those created by mitozolomide. Alkaline sucrose-density sedimentation was employed to detect genomic DNA damage. Also, the effects of the tetrazepinones on the cell cycle were determined by univariate flow cytometry. At 3 h post-treatment, mitozolomide appeared as a selective inhibitor of DNA synthesis, while both tetrazepinones inhibited the synthesis of all three macromolecules. At 24 h post-treatment, the inhibition of DNA synthesis was observed to increase in cells treated with mitozolomide, while it decreased in those previously exposed to the tetrazepinones. Also at 24 h post-treatment, mitozolomide induced accumulation of cells in S(late)/G2M at low concentrations and in S-middle at high concentrations. In contrast, at the same recovery time, cells treated with the tetrazepinones accumulated specifically in G2M, the strength of the block being dose-dependent. At an equimolar concentration, the tetrazepinones induced weaker guanine N-7 alkylation than mitozolomide. By 24 h after treatment, cells exposed to the tetrazepinones showed significantly greater DNA fragmentation than those previously treated with mitozolomide. In summary, based on (a) their effects on DNA, RNA, protein synthesis and on the cell cycle, (b) their alkylating power and (c) their interactions with DNA, the 3-(2-chloroethyl)tetrazepinones appeared to kill tumor cells by a novel mechanism which may significantly differ from that of their 3-(2-chloroethyl)-tetrazinone counterpart, mitozolomide.