Restoration of Normal Growth Control and Membrane Antigen Composition in Malignant Cells by Af,A/-Dimethylformamide1

The effects of the differentiation agent, A/,A/-dimethylformamide (DMF), on malignant AKR-MCA cells were studied. The properties of DMF-treated AKR-MCA cells were compared to those of the normal parental AKR-2B mouse embryo fibroblasts. AKR-MCA cells grown in 1% DMF were found to be more similar to their normal counterparts than to untreated AKR-MCA cells by several criteria. These criteria included the loss of the trans formed morphology, a 2-fold reduction of doubling time, a 10fold reduction of saturation density, and the complete loss of the ability to grow with anchorage independence. The expression of high-molecular-weight membrane antigens (Mr 110,000 to 450,000), which was found to be greatly reduced in AKR-MCA cells in comparison to normal AKR-2B cells, was restored by treatment of AKR-MCA cells with DMF. The expres sion of a low-molecular-weight AKR-MCA cell-associated mem brane antigen, on the other hand, was found to be suppressed. Studies on the mitogenic response of these cells indicated that AKR-MCA and AKR-2B cells may be regulated by different types of growth control. Growth-arrested AKR-MCA cells did not re spond to epidermal growth factor, but responded to nutrient replenishment. AKR-2B cells, on the other hand, responded to epidermal growth factor, but did not respond to nutrient replen ishment. Treatment of AKR-MCA cells with DMF restored their ability to respond to epidermal growth factor, while their ability to respond to nutrient replenishment was lost. The results of this study indicated that DMF treatment induced the normalization of malignant AKR-MCA cells with regard to membrane antigen composition and growth control properties.