The relative importance of NADPH: Cytochrome c (P450) reductase for determining the sensitivity of human tumour cells to the indolequinone EO9 and related analogues lacking functionality at the C-2 and C-3 positions

Analogues of EO9 (3-hydroxymethyl-5 -aziridinyl-1 -methyl-2[1H -indole-4-7- dione]prop-2-en-1-1-ol) which lack functionality at either the C-2 or C-3 p osition were synthesised. The aim was to establish the importance of each g roup towards toxicity and to give an indication as to whether substitution at either posit-ion altered activation and toxicity after metabolism by cel lular NADPH: cytochrome c (P450) reductase (P450R). MDA231 breast cancer ce lls were transfected with the cDNA for human P450R and stable clones were i solated. These high P450R-expressing clones were used to determine the aero bic and hypoxic toxicity of EO9 and the two analogues that lacked functiona lity at either C-2 or C-3. The results showed that P450R was strongly impli cated in the bioactivation of EO9 and its analogues under both of these con ditions. This data also showed that the C-3 functionality was primarily imp licated in hypoxic toxicity. (C) 2000 Elsevier Science Inc.