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Six human ovarian cancer cell lines and samples of ascites cells isolated from 27 patients with stage III or IV ovarian papillary serous cystadenocarcinoma were studied individually to test whether recombinant human Mullerian inhibiting substance (rhMIS) acts via its receptor. To do these experiments, we scaled up production of rhMIS and labeled it successfully with biotin for binding studies, cloned the human MIS type II receptor for mRNA detection, and raised antibodies to an extracellular domain peptide for protein detection. These probes were first tested on the human ovarian cancer cell lines and then applied to primary ovarian ascites cells. rhMIS inhibited colony growth of five of six cell lines that expressed the human MIS type II receptor mRNA by Northern analysis while not inhibiting receptor-negative COS cells. Flow cytometry performed on MIS-sensitive ovarian cancer cell lines demonstrated specific and saturable binding of rhMIS (Kd = 10.2 nM). Ascites cells from 15 of 27 or 56% of patients tested bound biotinylated MIS (MIS-biotin) and, of the 11 that grew in soft agarose, 9 of 11 or 82% showed statistically significant inhibition of colony formation. Of the 15 patients who bound biotinylated MIS, mRNA was available for analysis from 9, and 8 of 9 expressed MIS type II receptor mRNA by reverse transcription-PCR, showing a statistically significant correlation, compared with binding, by chi2 analysis (P = 0.025). Solid ovarian cancers were positive for the MIS type II receptor protein by immunohistochemical staining, which colocalized with staining for antibody to CA-125 (OC-125). Thus, the detection of the MIS type I receptor by flow cytometry may be a useful predictor of therapeutic response to MIS and may be a modality to rapidly choose patients with late-stage ovarian cancer for treatment with MIS.

Objectives: In this study we evaluated changes in serum Müllerian inhibiting substance (MIS) concentration in a large number of patients with granulosa cell tumors (GCT) to determine whether MIS is elevated at the time of presentation and whether MIS is an index of successful surgical resection and management of recurrences., Methods: We retrospectively reviewed MIS levels from 17 subjects prior to tumor resection and studied serial MIS samples from 56 subjects following initial tumor resection. Clinical follow-up information was available for 36 of those with postoperative MIS values. Serum MIS was measured by an ELISA. MIS values were compared to a combination of normative values previously established in our laboratory and from more recently obtained samples from older pre- and postmenopausal women, using this assay., Results: Serum MIS was elevated pre-operatively in 6 of 8 (75%) subjects with juvenile GCTs and in 7 of 9 (78%) of those with adult GCTs relative to age-matched controls (76% for both types combined). Post-operative clinical correlation was available for 36 patients. There was no clinical recurrence in 21 subjects with normal or undetectable postoperative values, and incompletely resectable tumor or recurrence was identified in 6 of 15 patients with elevated postoperative values., Conclusions: The results of this study demonstrate that postoperative serum MIS concentrations may be used to evaluate the completeness of tumor removal following initial surgery and that serial MIS determinations may allow the detection of recurrences., (Copyright 1999 Academic Press.)