Sister chromatid exchange in methotrexate resistant and sensitive C3H10T1/2 mouse cells.
Sister chromatid exchange (SCE) induction by methotrexate (MTX) was analyzed in C3H10T1/2 clone 8 mouse cells and in two MTX-resistant subclones with numerous double minute chromosomes (DM) present in the majority of cells. Significantly higher SCE levels were found, as expected, in sensitive cells after treatments with 10(-2) or 10(-5) M MTX but not in resistant cells permanently growing in the presence of a high concentration of MTX (2 x 10(-3) M) and characterized by a markedly lower cell cycle replication index (R.I.), i.e. in conditions that are known to otherwise favour SCE induction. These observations suggest, for the MTX-resistant cells under study, the existence of conditions limiting SCE formation.
Zamboni
M
M
Dipartimento di Genetica e di Biologia dei Microrganismi, Università di Milano, Italy.
Privitera
E
E
Mosna
G
G
Ghidoni
A
A
D000818:Animals; D002999:Clone Cells; D004351:Drug Resistance / Q000235:genetics; D008727:Methotrexate / Q000494:pharmacology*; D051379:Mice; D008809:Mice, Inbred C3H; D009693:Nucleic Acid Hybridization; D012854:Sister Chromatid Exchange
D008727:Methotrexate