INHIBITION OF 17-BETA-ESTRADIOL AND PROGESTERONE ACTIVITY IN HUMAN BREAST AND ENDOMETRIAL CANCER-CELLS BY CARBAMATE INSECTICIDES

Using a combination of in vitro assays we have examined the capacities of contemporary-exposure chemicals to modulate human estrogen and hum an progesterone receptor (hER and hPR) activity in human breast and en dometrial cancer cells. The carbamate insecticides aldicarb, Baygon (p ropoxur), bendiocarb, carbaryl, methomyl, and oxamyl were used in this study. The carbamates alone weakly activated estrogen- or progesteron e-responsive reporter genes in breast and endometrial cancer cells. Al l of the carbamates decreased estradiol- or progesterone-induced repor ter gene activity in the breast and endometrial cancer cells. In whole cell competition binding assays, the carbamates demonstrated a limite d capacity to displace radiolabeled estrogen or progesterone from ER o r PR. Based on the results presented here, the carbamate insecticides may represent a class of chemicals which function through a mechanism separate from ligand-binding and, therefore, may act as general endocr ine modulators in mammalian cells.