Human ovarian cancer, cell lines, and primary ascites cells express the human Mullerian inhibiting substance (MIS) type II receptor, bind, and are responsive to MIS

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.

Reduced fatty acid ethyl ester synthase activity in the white blood cells of alcoholics

PURPOSE

Fatty acid ethyl esters (FAEEs), esterification products of ethanol and fatty acids, have been implicated as mediators of ethanol-induced organ damage. It has been shown that FAEE synthase, the enzyme responsible for the formation of FAEE, is present selectively in the organs commonly damaged by ethanol abuse. Recently, we have made the observation that FAEEs are also present in the serum after ethanol ingestion. The current study was performed to determine whether cellular elements of the blood and/or plasma are capable of synthesizing FAEEs from fatty acids and ethanol.

MATERIALS AND METHODS

Heparinized blood samples were collected from 10 healthy volunteers, and the red blood cells, platelets, plasma, and several white blood cell populations were assayed for FAEE synthase activity. Blood samples from control subjects and individuals admitted to an alcoholic detoxification unit at a local hospital were also assayed for FAEE synthase activity.

RESULTS

We observed that the FAEE synthase activity is present in whole blood, primarily within white blood cells. Fractionation of the white blood cells revealed that the lymphocyte-monocyte fraction isolated using Ficoll-hypaque contained approximately 3.5-fold higher activity than the granulocyte fraction. The cell type that contained the highest FAEE synthase activity (1220 pmol/hr/10(6) cells) was the natural killer (NK) cell population. B cells contained approximately 40% of the enzyme activity found in NK cells, and the B-cell activity was slightly greater than that found in CD4+ and CD8+ T cells. Having shown that FAEE synthase exists in a blood cell, we subsequently demonstrated that alcoholic individuals have approximately half the white blood cell FAEE synthase activity of that found in normal controls. We also demonstrated that white blood cell FAEE synthase could be induced nearly 2-fold upon ingestion of 2 oz of scotch whiskey for 6 days. The enzyme activity returned to baseline levels despite ingestion of 2 oz of scotch whiskey/day for 3 additional days.

CONCLUSIONS

These data indicate that ethanol ingestion results in increased FAEE production, particularly by NK cells. FAEE synthesis after ethanol ingestion may explain the presence of FAEE in the serum. The lower enzyme activity observed in white blood cells of alcoholics from a detoxification center may be the result of years of ethanol abuse or it may be that alcoholics congenitally have low levels of FAEE synthase. If the latter is true, this finding may explain in part the genetic predisposition of many alcoholic individuals to ethanol abuse.