Effects of N-methylformamide on the growth, cell cycle, and glutathione status of murine TLX5 lymphoma cells

• Published in: Cancer research (Chicago, Ill.) Vol. 48; no. 12; pp. 3389 - 3393
• Main Authors: BILL, C. A, GESCHER, A, HICKMAN, J. A
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15.06.1988
• Subjects: Animals; Antineoplastic agents; Biological and medical sciences; Buthionine Sulfoximine; Cell Cycle - drug effects; Cell Survival - drug effects; Formamides - pharmacology; General aspects; Glutathione - metabolism; Lymphoma - metabolism; Lymphoma - pathology; Medical sciences; Methionine Sulfoximine - analogs & derivatives; Methionine Sulfoximine - pharmacology; Mice; Mice, Inbred CBA; Pharmacology. Drug treatments; Tumor Cells, Cultured; Antineoplastic agent; Cell proliferation; Vertebrata; Mammalia; Mouse; Animal; Rodentia; Inhibition; Experimental tumor; In vitro; Lymphoma; Glutathione
• ISSN: 0008-5472; 1538-7445

The growth of the murine TLX5 lymphoma is inhibited in vivo by administration of N-methylformamide (Gescher, A., et al., Br. J. Cancer, 45: 843-850, 1982). Continuous incubation of TLX5 murine lymphoma cells in vitro with N-methylformamide for 72 h, at concentrations of between 43 and 170 mM (0.25 and 1% v/v), brought about a concentration-dependent decrease in growth rate (50% inhibitory concentration = 68 mM) and viability. Cell replication was decreased by 37% after 48 h exposure to 106 mM N-methylformamide, while viability was maintained at 82%. Analysis of the distribution of these cells in the cell cycle by flow cytofluorimetry showed a 23% increase in the proportion of G1 cells and a fall in the proportion of cells in the S and G2/M phases. As the drug concentration and time of exposure to N-methylformamide were increased, with an associated reduction in cell replication and viability, the proportion of G1 cells rose. When TLX5 cells were washed free of N-methylformamide after an exposure to 106 mM for 48 h and cultured in drug-free medium, the cells returned to exponential growth and to a normal cell cycle distribution. Clonogenic assays showed that the recovery of proliferation, after removal of the drug, was due to that of all those cells which, in a parallel experiment, excluded the dye trypan blue. It is concluded that the cessation of replication and the accumulation of cells in G1 of the cell cycle, after treatment with N-methylformamide, are probably not events representative of terminal differentiation but rather of cytostasis, which was accompanied by rapid cell death. Coincident with the reduction of TLX5 cell proliferation caused by N-methylformamide and the accumulation of cells in G1, cellular glutathione concentrations fell by 80%. A similar fall was induced by treatment of the cells with D,L-buthionine[S,R]-sulfoximine (5 microM) for 48 h, but this treatment had no effect on cell growth.