Tumour-associated antigens for cystadenocarcinoma of the ovary

This chapter summarizes the various epithelial ovarian cancer markers which have been termed cystadenocarcinoma 'antigens'. Virtually every reported antigen has been demonstrated by raising antibodies to tumour extracts injected into heterologous animals. As yet, despite numerous attempts, no heterologous antiserum has been demonstrated to have the requisite sensitivity and specificity for the immunodiagnosis of early ovarian cancer. However, some of the antigen markers may prove useful in monitoring the response to therapy. Hybridoma-generated monoclonal antibodies could prove to be the means by which the immunodiagnosis of early ovarian cancer will be achieved. That the abnormal antigens reflect altered glycoprotein metabolism is suggested by the findings of elevated serum galactosyltransferase, which in itself is a good ovarian cancer tumour marker, and a genetic serum deficiency of alpha-L-fucosidase, which appears to identify a high risk population for the development of ovarian cancer.

Insect sex chromosomes. VIII. Identification of active/inactive X-chromosomes in Gryllotalpa fossor by 5-BrdU/AO fluorescence

By employing 5-BrdU/AO fluorescence technique to distinguish active from inactive X-chromosomes, we have, for the first time, provided evidence in support of the validity of this technique for a non-mammalian system Gryllotalpa fossor (Orthoptera). In the female somatic cells of Gryllotalpa, it is only in the active (euchromatic) arm of X-chromosome that the fluorescence is bright, whereas it is dull in the facultative and constitutive heterochromatic arms. In tetraploid spermatogonial cells one of the two X-chromosomes is inactive, suggesting that this phenomenon is probably a random one and that the inactivation process is independent of the imprinting mechanism.

Monoclonal antibodies recognizing tumor-associated antigen of human ovarian mucinous cystadenocarcinomas

Spleen cells from BALB/c mice immunized with human ovarian cystadenocarcinoma extract were fused with the mouse myeloma cell line P3/NSI/1-Ag 4 in the presence of polyethylene glycol (Mr 4000). Of the 46 hybrids obtained, four secreted antibodies preferentially reactive to the immunizing ovarian tumor extract. Two of these hybrids, which showed no reaction with normal controls, were selected for cloning by the limiting dilution method. The numerous clones obtained from each hybrid were screened against a panel of five ovarian tumor extracts, pooled normal ovary extracts, and pooled normal human sera. One clone from each hybrid that showed specificity for ovarian mucinous cystadenocarcinomas was recloned to assure monoclonality and to establish a permanent hybridoma cell line. The antibodies secreted by these cell lines were of IgG1 subclass with kappa light chains. These antibody-producing hybridomas were selected for further analysis of the antibody specificity by a solid-phase radioimmunoassay and quantitative absorption tests. The monoclonal antibodies recognized an antigenic determinant present only in mucinous cystadenocarcinomas of the ovary. These did not react with any other gynecological or nongynecological tumor thus far tested. The antigen was not demonstrable in any normal adult tissues tested. Among fetal tissues examined, only fetal intestine extract showed a positive reaction. The antigenic determinant recognized by these monoclonal antibodies was unrelated to carcinoembryonic antigen, normal glycoprotein, normal human serum components, or human ABO blood group materials. These antibodies, which have relatively high affinity and can be produced in large amounts, will be useful for the isolation and immunochemical characterization of this antigen. The purified antigen and the specific antibodies could be then combined in a sensitive radioimmunoassay for the early detection of the antigen in the sera and body fluids of patients with ovarian mucinous cystadenocarcinomas.

Beta-hexosaminidase activities and isoenzymes in normal human ovary and ovarian adenocarcinoma

Levels and isoenzyme profiles of beta-hexosaminidase were compared in extracts from normal ovarian and ovarian epithelial tumors. The specific activities of beta-hexosaminidase were significantly (P less than 0.001) higher in malignant than in normal ovarian tissues. The enzyme levels of the tumors depended on their degree of differentiation. Well-differentiated tumors had activities in the normal range, while poorly differentiated ones had values higher than the normal mean +/- 2 SD. The moderately and moderately to poorly differentiated tumors had intermediate levels. DEAE-cellulose chromatography was used to resolve the isoenzyme of beta-hexosaminidase. Two major forms, beta-hexosaminidase A and beta-hexosaminidase B, were detected in all the preparations. In one tumor specimen, a component eluting slightly ahead of beta-hexosaminidase A was also detected. For quick separation, a batch-wise procedure using DEAE-cellulose was adapted. Proportions of the isoenzymes A and B separated by batch-wise procedure were similar to those obtained by column chromatography. Heat stability, optimum pH, acid stability and substrate specificity of the beta-hexomsaminidase isoenzymes from ovarian tissues were similar to those from other human sources. Isoenzymes from tumor extracts were more labile to heat and acid pH compared with those from normal source. Slight differences in the affinity for the substrate p-nitrophenyl-beta-N-acetyl-galactosaminidase between the isoenzymes from normal and malignant ovaries were noted.

Evaluation of 5'-nucleotidase as an enzyme marker in ovarian carcinoma

A plasma membrane ectoenzyme in mammalian cells, 5'-nucleotidase, was evaluated as a marker for ovarian carcinoma. Activities of this enzyme were determined in homogenates from normal (N = 17) and malignant ovaries (N = 17), as well as in the sera from control women (N = 35), ovarian cancer patients with active disease (N = 24), and those in clinical remission (N = 9). A significant reduction of the activity of 5'-nucleotidase was observed in tumor homogenates compared with homogenates from normal ovaries. Levels of this enzyme in the sera of ovarian cancer patients were higher than in control women, suggesting the possibility of shedding of this enzyme from the tumor cell surface to the systemic circulation of the host. The diagnostic value of serum 5'-necleotidase levels was compared with another enzyme marker for ovarian carcinoma, viz. serum glycoprotein:galactosyltransferase. The upper limit of normal was set at 2 SD higher than the normal mean. Elevation of serum 5'-nucleotidase was observed in 12/24 (50%) patients with active disease, and 1/9 (11%) patients with clinical remission. In contrast, serum glycoprotein:galactosyltransferase was elevated in all the serum samples from patients with active disease and in none of those with clinical remission. There was some correlation between the serum levels of 5'-nucleotidase and those of glycoprotein:galactosyltransferase (0.01 less than P less than 0.05). Elevation of 5'-nucleotidase in the serum of these patients was not due to liver metastasis. Serum 5'-nucleotidase levels seem to correlate with disease status in some ovarian carcinoma patients, but in general it is inferior to serum glycoprotein:galactosyltransferase as a tumor marker.

Determination of serum galactosyltransferase levels in ovarian cancer patients for the evaluation of the effectiveness of therapeutic programs

The activity of galactosyltransferase using endogenous acceptor(s), (GT-En) in the sera of ovarian cancer patients was significantly higher than age and blood-group matched controls. GT-En, and galactosyltransferase activity using an exogenous acceptor (GT-Ex), were assayed in the sera of 30 patients undergoing treatment for ovarian epithelial cancer, at the start of chemotherapy, and after a suitable interval. The direction of the alterations in levels of both these enzymes correctly reflected the clinical response to chemotherapy in most of these patients. The assay of GT-En and GT-Ex in the serum may be useful for the evaluation of the effectiveness of therapeutic programs in these patients.

Glycosyltransferase and glycosidase activities in ovarian cancer patients

In order to elucidate the mechanism of appearance of abnormal glycoproteins in cancer, activities of glycoprotein glycosyltransferases and glycosidases were determined in the homogenates prepared from normal ovaries and ovarian epithelial adenocarcinoma. Significantly high activities (more than normal mean + 2 S.D.) of these enzymes were found as follows: galactosyltransferase and sialytransferase in 100%; fucosyltransferase 1 (exogenous acceptor, fetuin minus sialic acid and galactose) in 86%; fucosyltransferase 2 (fetuin minus sialic acid, acceptor) in 45%; N-acetylglucosaminyltransferase 1 (ovalbumin acceptor) in 53%; N-acetylglucosaminyltransferase 2 (ribonuclease A as acceptor) in 10% of the samples analyzed. Among the glycosidases, substantially elevated activities above normal controls were found as follows: N-acetyl-beta-D-glucosaminidase in 85%; N-acetyl-beta-D-galactosaminidase in 63%; N-acetyl-beta-D-galactosidase in 50%, and those of alpha-L-fucosidase in 35% of the tumors. In serum of these cancer patients, only levels of galactosyltransferase were consistently elevated compared to controls. Increases in serum levels for other transferases were as follows: fucosyl-1, 10%; fucosyl-2, 60%; sialyl-, 20%; N-acetylglucosaminyl-1, 90%; N-acetylglycosaminyl-2, in 80% of the serum samples from ovarian carcinoma patients. Galactosyltransferase thus appears to be an excellent marker for ovarian carcinoma.

Treatment and immunodiagnosis of advanced ovarian adenocarcinoma: a preliminary report

High-dose methotrexate with leucovorin rescue plus cyclophosphamide resulted in a 66.6% objective response rate with a 50% complete response rate. These preliminary results are higher than our previous results with melphalan alone or actinomycin D, 5-fluorouracil, and cyclophosphamide in women with advanced ovarian adenocarcinoma. Circulating ovarian cystadenocarcinoma-associated antigen serum levels were positive in 69.8% of patients and correlated with response to chemotherapy in 70% of patients. To date, all of the patients with advanced ovarian adenocarcinoma were found to have elevated galactosyltransferase levels. Galactosyltransferase levels correlated with response to therapy in the first five patients followed serially.

Correlation of UDP-galactose glycoprotein:galactosyltransferase levels in the sera with the clinical status of ovarian cancer patients

Uridine diphosphate-galactose : glycoprotein galactosyltransferase (EC 2.4.1.22) was measured serially prior to and after surgery in 4 patients with ovarian epithelial cancer. The levels of this enzyme in the sera correlated well with the clinical status of the patients. In 2 other patients, the follow-up was designed to detect recurrence, and the enzyme assay was started when the patients were clinically disease free. Elevation of galactosyltransferase preceded the clinical appearance of disease by 3-7 months. Serial determination of glycoprotein galactosyltransferase in serum may be useful for evaluating the effectiveness of therapeutic programs.

Ovarian tumor antigens

Evidence has been reported for at least two common tumor-associated antigens, or antigenic determinants, in human cystadenocarcinomas of the ovary that are apparently absent in tissues of normal reproductive organs. These antigenic determinants are immunologically distinct from carcinoembryonic antigen, alpha-fetoprotein, ferritins and histocompatibility antigens. One of these two ovarian cystadenocarcinoma-associated antigens (OCAA) is not detectable in any ovarian carcinomas except serous or mucinous types, other gynecologic or nongynecologic malignancies thus far tested, while the second antigen is present in about 90% of all gynecologic tumors and occasionally in breast and colon tumors. OCAA has been purified and partially characterized. It is a high molecular weight glycoprotein which carries the unique ovarian tumor-specific antigenic determinant along with some normal cross-reacting determinants. High levels of this glycoprotein antigen have been detected in the sera of ovarian cancer patients with advanced disease by the radioimmunoassay inhibition technique. The serial determination of circulating OCAA appeared to correlate with tumor volume as well as the clinical status of the patients.

Uridine 5'-diphosphate-galactose:glycoprotein galactosyltransferase activity in the ovarian cancer patient

Uridine 5'-diphosphate-galactose:glycoprotein galactosyltransferase activity was demonstrated in homogenates of normal ovary and ovarian epithelial adenocarcinomas. The specific activity of the enzyme in ovarian tumors was 3 to 5 times higher than in normal ovaries when the enzyme was assayed under identical conditions. The glycoprotein fetuin, from which terminal sialic acid and penultimate galactose were removed (fetuin minus N-acetylneuraminis acid and galactose), acted as an excellent exogenous acceptor. Galactosyltransferase from normal ovary and ovarian tumor cells had similar properties. Both required Mn2+ and Triton X-100 and had broad pH optima between 5.5 and 7. Galactosyltransferase activity was also measured in serum samples from ovarian cancer patients and normal healthy individuals in the presence of fetuin minus N-acetylneuraminic acid and galactose as exogenous acceptor. The enzyme levels were significantly elevated in the sera of ovarian cancer patients as compared to normal controls. The differences in the levels of this enzyme in the tissues and sera of normal individuals and ovarian cancer patients were not due to differential levels of the degrading enzymes such as uridine 5'-diphosphate-galactose pyrophosphatase or beta-D-galactosidase. Serial determinations were carried out on the sera of 5 ovarian cancer patients over a long period of time. The serum level of galactosyltransferase activity appeared to correlate with tumor volume as well as with the clinical status of the patient, which suggests possible leakage of the tumor enzyme into the host sera. Serial determination of this enzyme level in ovarian cancer patients seems promising in measuring tumor progression or success of therapeutic approaches.

Tumor-associated antigen for cystadenocarcinomas of the ovary

An ovarian cystadenocarcinoma-associated antigen (OCAA) was found to be common to all serous and mucinous cystadenocarcinomas of the ovary. It was apparently absent in tissues of normal reproductive organs. Furthermore, OCAA was not detected in benign ovarian serous and mucinous cyst-adenomas or in any other gynecologic or nongynecologic cancers thus far tested. The antigenic determinant of OCAA was immunologically unrelated to the carcinoembryonic antigen, other known tumor antigens, or the histocompatibility antigens. We purified and partially characterized OCAA. The antigen was a high-molecular-weight glycoprotein soluble in 0.6 M perchloric acid. It consisted of about 50-60% protein (based on dry wt). Amino acid composition in OCAA was characterized by a high percentage of threonine, serine, proline, and valine. Galactose and N-acetylglucosamine were the principal carbohydrate constituents. The antigenic activity was resistant to treatment with trypsin and protease and also to treatment with DNase, RNase, and N-acetylneuraminidase. The antigenicity was considerably reduced by mild periodate oxidation.