EXPRESSION AND LOCALIZATION OF INHIBIN ACTIVIN SUBUNITS AND ACTIVIN RECEPTORS IN MCF-7 CELLS, A HUMAN BREAST-CANCER CELL-LINE/

Inhibins and activins are members of the transforming growth factor-be ta (TGF beta) superfamily. Since TGF beta has been shown to be a poten t proliferation-inhibiting agent for the breast cancer cell line MCF-7 , we determined whether this cell line (a) transcribes messenger RNAs coding inhibin/activin alpha-, beta A-, and beta B-subunits and activi n receptors, and (b) produces inhibin and/or activin proteins. Messeng er RNAs for alpha- and beta-sub units of inhibin/activin and activin r eceptor II in MCF-7 cells were detected and localized using the revers e transcription-polymerase chain reaction (RT-PCR) analysis and in sia l hybridization, respectively. The identity of the RT-PCR products was confirmed by DNA sequencing of PCR products. Immunocytochemically, in hibin and activin were localized in these cells. Our findings that mes senger RNAs encoding inhibin alpha-subunit, inhibin/activin beta A-sub unit, and activin receptor II were expressed, and inhibin/activin prot eins were produced by MCF-7 cells, imply that these gonadal growth fac tors may have paracrine/autocrine functions in human breast cancer. Fu rther, these observations suggest that these growth factors may be inv olved in regulating the growth and differentiation of human breast can cer cells.