CHARACTERIZATION OF MULLERIAN-INHIBITING SUBSTANCE BINDING ON CERVICAL-CARCINOMA CELLS DEMONSTRATED BY IMMUNOCYTOCHEMISTRY

Mullerian inhibiting substance (MIS) is a glycoprotein released from S ertoli cells or follicular cells of gonads, responsible for the regres sion of Mullerian ducts and/or Mullerian-derived tumor cells. Binding of MIS to target cells is essential for initiating regression. A human cervical carcinoma CaSki cell was examined by quantitative immunocyto chemistry detected by anti-avian MIS antibody for MIS binding ability. Various treatments of WGA-peroxidase conjugate, enzyme digestion, sod ium periodate or exogenous estrogen before antibody recognition were p erformed. It was found that the WGA partially blocked MIS binding to C aSki cell surfaces. Protease digestion of CaSki cell surfaces prior to addition of MIS or an anticervical carcinoma monoclonal antibody 1H10 (MAb 1H10), blocked the binding of MIS but not MAb 1H10 to cell surfa ces. Sodium periodate and overnight exposure of CaSki cells to estroge n or diethylstilbestrol before or after fixation of the cells, did not influence MIS binding ability in vitro. MIS binding was higher on avi an Mullerian duct compared with MIS binding to CaSki cells by quantita tive immuno-gold labeling analysis. MAb 1H10 immuno-gold complexes bin ding to CaSki cells was also obtained and compared with MIS immuno-gol d bindings. MIS binding site could be a polypeptide which survived sod ium periodate treatment. The 'critical window' period, in which develo ping Mullerian ducts respond to exogenous estrogen protection from MIS regression, is possibly lost in CaSki cell.