Mixtures of benomyl, pirimiphos-methyl, dimethoate, diazinon and azinophos-methyl affect protein syntheis in HL-60 cells differently

Dimethoate, azinphos-methyl, diazinon and pirimiphos-methyl, widely used organophosphorous insecticides, and benomyl, a benzimidazole fungicide, induce different cytotoxic effects on the human leukemia cell line HL-60. Among the insecticides tested, only azinphos and diazinon induced a dose-related inhibition of protein synthesis in HL-60 cells at 24 h, at 60 and 40 μg/ml medium, respectively. Dimethoate and pirimiphos were not active up to 100 μg/ml. Benomyl strongly inhibited protein synthesis at 50 μg/ml and the polymerisation of actin to give cytoskeletal microfilaments (F-actin) at 30 μg/ml. Mixtures of benomyl-pirimiphos and dimethoate azinphos-diazinon were also investigated. Pirimiphos, when present in equal concentration, antagonized the inhibitory effect of benomyl on protein synthesis at 4 h, but not at 24 h. The effect of the other insecticide mixture on the same parameter was greater than that of the two active components, diazinon and azinphos given singly.