SEX STEROID-BINDING PROTEIN-RECEPTOR (SBP-R) IS RELATED TO A REDUCED PROLIFERATION RATE IN HUMAN BREAST-CANCER

In the last years, an increasing amount of studies described a membran e receptor for the Sex Steroid Binding Protein (SEP) on several androg en-estrogen dependent tissues. One of the suggested biological roles o f the interaction between SEP and its receptor seems to be a negative control of the E(2) induced proliferation of human breast cancer cells through the cAMP pathway. In the present work, SEP membrane receptor was evaluated on human breast cancer specimens with a radio-binding as say. Each tissue sample was also evaluated for ER and PGR status. Cyto sol Thymidine Kinase levels were measured in tissue samples in order t o evaluate cell proliferation rate. SBP binding to membranes of ER+/PG R+ samples was time and temperature dependent, specific and at high af finity. In addition, SBP recognized on breast cancer membranes two sit es at different affinity, as previously described for other human tiss ues and cultured cells. Membrane SBP-R was detected in a significantly higher number of samples positive for both ER and PGR than in negativ e samples. SBP-R positive samples showed a significantly lower prolife ration rate than SBP-R negative samples as demonstrated by TK activity . The present study contains evidences for the existence of a specific membrane receptor for SEP in breast cancer sample membranes and the p resence of SBP-R seems to be strictly related to a lower proliferation rate of the sample.