Interferon‐β can induce progesterone receptors in human endometrial adenocarcinoma

BACKGROUND. The induction of estrogen and progesterone receptors (ER and PGR) has been reported in breast and endometrial cancer cells exposed to human fibroblast interferon-β (hIFN-β). Clinical verification of this finding might provide the rationale for new therapeutic approaches. This study was designed to evaluate whether clinical treatment with high doses of hIFN-β induced ER and PGR in patients with endometrial adenocarcinoma. METHODS. Two biopsies were obtained, I before and 1 after hIFN-β treatment (3 x 10 6 i.m. every other day for 3 weeks) from 36 patients with endometrial adenocarcinoma. ER and PGR were determined with standard procedures using radiolabeled ligands. RESULTS. hIFN-β treatment did not affect the proportion of ER-positive (i.e., >15 fmol/mg protein) or PGR-positive (i.e., >20 fmol/mg protein) cases. However, in patients with detectable ER and PGR at baseline, hIFN-β raised the levels. Using a 35% difference before and after therapy as a cut-off, 72 and 79% of cases had increases in ER and PGR, respectively. The difference was highly significant for PGR. CONCLUSIONS. In patients with endometrial adenocarcinoma with undetectable ER or PGR, hIFN-β did not induce the expression of these receptors. When the receptors were present they were upregulated by hIFN-β. Whether this increase in receptor levels, particularly PGR, has therapeutic applications remains to be established.