N,N-Dimethylformamide treatment of cell cultures established from a transplantable murine rhabdomyosarcoma-induced morphological differentiation and a marked reduction in the tumorigenicity of the sarcoma cells. Fourteen of 17 CE/J mice receiving injections of inducer-treated cells did not develop tumors after 6 months, whereas all 21 mice receiving inocula of untreated sarcoma cells died of disease between 11 and 31 days. The drug-treated cells did not grow in soft agar; untreated tumor cells grew in the semisolid medium. The untreated tumor cells showed a reduced serum requirement and had a higher saturation density compared to drug-treated cells. Thus the reduction in tumorigenicity of N,N-dimethylformamide-treated cells correlates with certain in vitro growth properties that are more characteristic of normal, mesenchymally derived cells than of sarcoma cells.


This work was supported by USPHS NIH Grants CA14520, CA13548, and CA13943. Part of this study was completed at the Wisconsin Clinical Cancer Center, University of Wisconsin, Madison, Wis. 53706.

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