Use of a DNA Microfluorometric Assay to Measure Proliferative Response of Mink Lung Cells to Purified TGFβ and to TGFβ Activity Found in Prostate Cell Conditioned Medium

The proliferative response of Mv1Lu cells to purified$TGF\beta_1$or$TGF\beta-like$activity released by various cells into medium conditioned over a 24-h period was quantitated by adapting a rapid DNA fluorometric assay. Acid activation of the conditioned medium allowed the amount of biologically latent versus active TGFβ to be quantitated. A neutralizing antibody specific for$TGF\beta_{1, 1.2, and 2.0}$completely blocked the growth inhibition observed treating Mv1Lu cells with either purified$TGF\beta_1$or medium containing secreted$TGF\beta-like$activity conditioned by DU 145 prostate cells. In contrast to other assays commonly used to measure TGFβ activity, the proliferative response is related directly to DNA content rather than as a reflection of enzymatic activity or incorporation of3H-thymidine. The necessity for radioactive isotope usage has been eliminated, and the biological response can be quantitated over a period of days.