Characterization of amyloid fibril proteins from medullary carcinoma of the thyroid.

Amyloid fibrils were studied from two different tissues of medullary carcinoma of the thyroid (MCT). The fibrils mainly consisted of a low molecular weight protein, AMCT, which was immunologically distinct and did not react with various antisera against known amyloid fibril proteins. A specific antiserum raised against the MCT amyloid proteins gave a reaction of identity with the degraded MCT amyloid fibrils from two patients, as well as with the isolated AMCT protein, but showed no reaction with other known amyloid proteins. The AMCT protein had a blocked N terminus, but the sequence analysis of a cyanogen bromide fragment revealed identity with human calcitonin in the 11 positions studied. Although the amino acid composition was similar, there were also distinct differences, and the mol wt of 5,700 daltons was considerably larger than that of calcitonin. For these reasons the AMCT protein may represent a prohormone of calcitonin.

Purification and partial primary sequence of a chemotactic protein for polymorphonuclear leukocytes derived from human lung giant cell carcinoma LU65C cells.

A chemotactic protein for polymorphonuclear leukocytes (lung carcinoma-derived chemotaxin [LUCT]) was purified from culture fluid of the human lung giant cell carcinoma LU65C cells to electrophoretically homogeneous form through five sequential purification steps: DEAE-Sepharose, CM-Sepharose, HPLC on carboxyl-methylated-polyvinylalcohol resin, hydrophobic, and reversed-phase. The molecular mass was determined as approximately 10 kD by SDS-PAGE and isoelectric point was 10.7. The chemotactic activity (ED50 0.75 x 10(-9) M) was sevenfold more potent than that of FMLP (5 X 10(-9) M) and comparable with that of C5a (10(-9) M). NH2-terminal amino acid sequence and amino acid composition of LUCT strongly suggest that it may be closely related to the putative protein encoded by the cDNA clone (3-10C) and almost identical with a part of sequence of the chemotactic factor derived from stimulated human leukocytes in the 6th to 32nd, but not the NH2-terminal 5 amino acids. These results indicate that the carcinoma cells produce LUCT without any added stimulant and suggest that the previously isolated chemotactic monokines may correspond to des(1-5) of LUCT in the NH2-terminal region.

Human alpha-lactalbumin: measurement in serum and in breast cancer organ cultures by radioimmunoassay.

A sensitive and specific radioimmunoassay for human alpha-lactalbumin, a major milk protein, is described. Some normal men and women have detectable levels of alpha-lactalbumin in their blood. High values are found in nursing mothers and many patients with galactorrhea. Alpha-Lactalbumin is found in some breast cancer organ cultures. In addition, alpha-lactalbumin output was stimulated by ovine prolactin in 2 of the 19 tumors studied.

Elevated serum thyroglobulin. A marker of metastases in differentiated thyroid carcinomas.

The presence of human thyroglobulin (HTg) in serum of patients was identical by immunological criteria to the serum standard used in the radioimmunoassay. The serum thyroglobulin levels in untreated patients with differentiated thyroid carcinoma ranged from 22.0 to 445.0 ng/ml with a mean of 144.3 +/- 46.5 ng/ml (SEM) (n = 10). The mean serum thyroglobulin measured postoperatively in seven of these patients was 6.4 +/- 1.5 ng/ml, not statistacally different from the mean level of 5.1 +/- 0.49 ng/ml (range 0-20.7 ng/ml) observed in 71 out of 95 control subjects with detectable HTg levels. By contrast serum HTg levels were normal or undetectable in subjects with medullary carcinoma of the thyroid. HTg levels were within normal limits in sera of patients who had previously undergone successful therapy for a differentiated thyroid carcinoma and in whom no metastases could be documented. The mean level for this group was 4.9 +/- 0.51 ng/ml (n = 43). In contrast, patients with documented metastases had a mean serum thyroglobulin level of 464.9 +/- 155.6 ng/ml (n = 6). The data support the thesis that in differentiated thyroid carcinoma serum thyroglobulin levels are elevated when metastases develop after initial treatment. It is proposed that the measurement of thyroglobulin in the serum represents a simple and valuable adjunct in the posttreatment follow-up of patients with differentiated thyroid cancer.

Localization of transforming growth factor alpha and its receptor in gastric mucosal cells. Implications for a regulatory role in acid secretion and mucosal renewal.

Transforming growth factor alpha (TGF alpha) shares with epidermal growth factor (EGF) structural homology (35%), a common cell-surface membrane receptor (TGF alpha/EGF receptor), and a nearly identical spectrum of biological activity, including inhibition of gastric acid secretion. Herein, we report expression of TGF alpha mRNA in normal gastric mucosa of the adult guinea pig, rat, and dog. TGF alpha mRNA was also detected in matched surgically resected gastric mucosa and adjacent gastric carcinoma from 10 patients, and in gastric mucosa adjacent to a benign ulcer from an additional patient. TGF alpha protein was quantitated by radioimmunoassay and was present in tumor and adjacent mucosa. TGF alpha/EGF receptor mRNA was also detected in gastric mucosa from all species studied. Localization of TGF alpha and TGF alpha/EGF receptor mRNA expression was examined in samples of unfractionated guinea pig gastric mucosa and from chief cell-enriched and parietal cell-enriched fractions. All samples exhibited TGF alpha and TGF alpha/EGF receptor expression. The TGF alpha signal was greatest in the parietal cell fraction (5.8-fold increase), but was also enhanced in the chief cell fraction (1.9-fold increase) relative to the unfractionated gastric mucosa. Like TGF alpha expression, TGF alpha/EGF receptor mRNA expression was most intense in the parietal cell-enriched fraction (7.8-fold increase), but was also increased in the chief cell-enriched fraction (2.7-fold increase) relative to the unfractionated guinea pig gastric mucosa. We conclude that TGF alpha and TGF alpha/EGF receptor genes are expressed in normal adult mammalian gastric mucosa. These findings, when interpreted in light of described actions of TGF alpha and EGF, provide evidence that local production of TGF alpha could play an important role in the regulation of acid secretion and mucosal renewal in the stomach.

Epidermal growth factor receptor expression in human lung carcinomas defined by a monoclonal antibody.

Acetone-fixed frozen tissue sections from 56 cases of human lung carcinoma were tested for reactivity by an indirect immunoperoxidase technique with a monoclonal antibody (MAb 528) specific for the external domain of the epidermal growth factor receptor (EGFR). MAb 528 reacted with all epidermoid (22/22) and large-cell (4/4) lung carcinomas evaluated. The antibody was also positive with a subset of lung adenocarcinomas (13/21) and did not react with small-cell lung cancers (SCLCs) (0/9). MAb 528 also stained normal bronchial epithelium identified within the tumor sections of 5 cases. Thus EGFR was expressed by all epidermoid and large-cell lung carcinomas examined, a subset of lung adenocarcinomas, and normal bronchial epithelium. EGFR expression was not identified in any of the SCLCs tested. These data imply that immunohistochemical detection of EGFR expression may find future application in distinguishing epidermoid, large-cell, and some adenocarcinomas of the lung from SCLCs.

Tumor-associated glycoprotein (TAG-72) in ovarian carcinomas defined by monoclonal antibody B72.3.

Murine IgG1 monoclonal antibody (MoAb) B72.3, reactive with a high molecular weight glycoprotein complex [designated tumor-associated glycoprotein-72 (TAG-72)] was shown, with the use of the avidin-biotin-complex-immunoperoxidase technique and surgically resected tissues, to be reactive with a variety of histologic tumor types. TAG-72 is expressed in at least 5% (and up to 100%) of the malignant epithelial cells in 77% (n = 52) of human primary cancers and 71% (n = 31) of metastatic ovarian cancers of the common "epithelia" histologic category. Of these, several histologic types, including serous and mucinous cystadenocarcinomas, undifferentiated carcinomas, and less common types of ovarian carcinoma, were all shown to express TAG-72. In contrast, normal ovarian tissues and 26 of 27 benign ovarian tumors of various histologic types failed to express similar levels of TAG-72. Of interest is the 1 benign tumor that demonstrated unusual glandular complexity, as well as 3 tumors designated as borderline malignancy, that contained elevated TAG-72 expression. MoAb B72.3 also was used successfully to detect ovarian carcinoma cells in 28 cytologic preparations of human serous effusions and peritoneal washings. The reactivity of MoAb B72.3 was shown to be distinct from that of MoAb OC125 and an anti-CEA MoAb B1.1. The potential applications of MoAb B72.3 in the study of human ovarian cancer cell populations, as well as in several aspects of the management of human ovarian cancer, are discussed.

Molecular forms of katacalcin, calcitonin gene-related peptide and gastrin-releasing peptide, in a human medullary thyroid carcinoma.

Peptides synthesized by a human medullary thyroid carcinoma were purified to homogeneity by reverse-phase high performance liquid chromatography and structurally characterized by determination of amino acid composition, amino acid sequence, and fast atom bombardment mass spectra. The katacalcin-related material in the tumor extract was heterogeneous. Katacalcin (1-21) represented the predominant molecular form but metabolites, identified as katacalcin (1-20), (1-19), (1-15) and (1-13), were also identified in high concentration. Calcitonin gene-related peptide-I was isolated from the tumor but calcitonin gene-related peptide-II was absent. A minor component of calcitonin gene-related peptide-like immunoreactivity was of higher molecular weight and may represent an incompletely processed form of the prohormone. Gastrin-releasing peptide (1-27) and gastrin-releasing peptide (18-27) (neuromedin C) were isolated from the tumor but gastrin-releasing peptide (14-27) and bombesin were absent.

Use of a monoclonal anti-estrogen receptor antibody in the immunohistochemical evaluation of human tumors.

A monoclonal antibody to human estrogen receptor protein (H222 Sp gamma), amplified via immunoperoxidase techniques, was used in the analysis of estrogen receptor in 452 breast carcinomas, 100 endometrial carcinomas, and 15 melanomas. Immunohistochemical evaluation incorporated both intensity and distribution of staining (HSCORE). Quantitative estrogen receptor content was determined by dextran-coated charcoal analysis and sucrose density gradient analysis. In all cases H222 Sp gamma localized in the nucleus of target cells. A semiquantitative correlation existed between HSCORE and biochemical assays for breast and endometrial tissues. The sensitivities and specificities for HSCORE as compared to the biochemical assays ranged from 80 to 95% and from 74 to 94%, respectively. HSCORE correlated with tumor grade for breast and endometrial carcinoma. Immunohistochemical evaluation showed no specific staining in melanomas. The data suggest that immunohistochemical receptor localization provides information complementary to standard biochemical assays in the tissues studied.

Enhanced levels of insulin-like growth factor messenger RNA in human colon carcinomas and liposarcomas.

The insulin-like growth factors I and II (IGF-I and -II) are proteins which stimulate cell proliferation and are important in normal human growth and development. They are coded for by separate genes and bind to specific cell surface receptors, eliciting a mitogenic response. IGFs are secreted by several cell lines derived from adult tumors. We have examined a number of human adult tumors for IGF messenger RNA (mRNA) expression and found IGF-II mRNA levels were consistently elevated in two types, colon carcinoma and liposarcoma. Adult colonic mucosa contains low levels of IGF-I and -II mRNA while several colon tumors, particularly of rectal and rectosigmoid origin, contained significantly elevated levels of IGF-II message. Over 90% of liposarcomas examined contained greatly elevated levels of IGF-II mRNA while control tissue (adipose) contained very low or undetectable IGF mRNA levels. Many of these tumors also contained elevated IGF-I mRNA levels. Northern analysis of these RNAs revealed differences in the abundance and sizes of IGF transcripts compared to other normal and malignant tissues known to express IGF.

Cytokeratin characterization of human prostatic carcinoma and its derived cell lines.

Two murine monoclonal anti-cytokeratin antibodies with defined specificity were shown to distinguish between basal cells and luminal cells in human prostate tissue. Forty-one biopsies or transurethral resection specimens were characterized using these two antibodies. In cases of benign prostatic hyperplasia, focal loss of the basal cell layer was noted in areas of glandular proliferation. Ten cases of adenocarcinoma of the prostate, varying in Gleason's histological grade from 2 to 4, were also studied. In each case the carcinoma was shown to represent the luminal cell phenotype with no evidence of involvement of the basal cell phenotype. An analysis of three established metastatic prostatic carcinoma cell lines (DU-145, PC-3, and LNCaP) using two-dimensional electrophoresis showed that the cytokeratin complement of each cell line was slightly different but retained the phenotype of the luminal cell. It was concluded that during both hyperplasia and neoplastic transformation of the prostate, the luminal cell phenotype is primarily involved and that the basal cell phenotype does not appear to contribute to either intraluminal proliferation or invasive cell populations.

Expression of epidermal growth factor receptor in human gastric and colonic carcinomas.

The expression of epidermal growth factor (EGF) receptor was examined immunohistochemically in a total of 122 gastric and 61 colonic carcinomas, out of which 16 gastric and 8 colonic carcinomas were also examined by 125I-labeled EGF binding analysis and Western blotting. The values of EGF binding were 12.68 +/- 1.98 (SE; n = 16) fmol/mg protein in gastric carcinomas and 5.72 +/- 2.15 (n = 8) fmol/mg protein in nonneoplastic gastric mucosa, the difference being significant (P less than 0.01). In the colonic tissue, the binding capacities in carcinomas and nonneoplastic mucosa were 13.29 +/- 4.17 (n = 8) and 10.68 +/- 0.41 (n = 3) fmol/mg protein, respectively. Scatchard analysis of 125I-labeled EGF binding indicated a single class of receptors in gastric and colonic carcinomas with an apparent Kd value of from 111 to 277 (n = 4) and from 87.4 to 341 fM (n = 5), respectively, except for one gastric carcinoma having two classes of receptors (Kd = 15.9 and 896 fM). In Western blotting using monoclonal anti-EGF receptor antibody, various levels of EGF receptor expression were detected in 12 (85.7%) of the 14 gastric carcinomas and in 7 (87.5%) of the 8 colonic carcinomas. Immunohistochemically, EGF receptor immunoreactivity was detected in one (3.8%) of the 26 early gastric carcinomas, while it was observed in 33 (34.4%) of the 96 advanced gastric carcinomas, the incidence between the two being significantly different (P less than 0.01). In the colonic carcinomas, 47 (77.1%) of the 61 cases showed positive immunoreactivity to EGF receptor, which did not differ by histological type.

Differences in lectin reactivities of cellular glycoconjugates between primary human colorectal carcinomas and their metastases.

Recent studies have demonstrated that colonic carcinomas consist of heterogeneous populations of cells endowed with different abilities to metastasize. Increasing evidence suggests that cell surface carbohydrates may play an important role in cancer invasion and metastasis. Therefore the binding of five fluorescein isothiocyanate-conjugated lectins to cellular glycoconjugates was analyzed immunohistochemically in paraffin-embedded tissue sections obtained from 16 colorectal carcinomas and their 25 metastases. In positive cases peanut agglutinin (galactose beta 1----3N-acetylgalactosamine), Ulex europeus' agglutinin 1 (alpha-L-fucose), Griffonia simplicifolia agglutinin 1 (galactose), Vicia villosa agglutinin (N-acetylgalactosamine), and G. simplicifolia agglutinin 2 (N-acetylglucosamine) stained apical cell membranes in carcinomatous glands and intraluminal secretions. Nine of 16 primary colorectal carcinomas showed intratumoral heterogeneous cell populations with regard to the lectin binding which resulted in areas of fluorescence-positive and fluorescence-negative carcinomatous glands. Only one liver metastasis showed this intralesional heterogeneity in lectin binding. Nineteen of 25 metastatic tumors produced cellular glycoconjugates which differed in their lectin binding profiles from those made by the majority of the cells in the respective primary colorectal carcinomas. The findings of the present work suggest that many primary colorectal carcinomas consist of phenotypically distinct subpopulations of carcinomatous cells. Most metastatic tumors appeared to result from a selective emergence of carcinoma cells producing glycoconjugates which differed in their lectin-binding profiles from those in their respective primary colorectal carcinomas.

Modulation of carcinoembryonic antigen messenger RNA levels in human colon carcinoma cells by recombinant human gamma-interferon.

Recombinant human interferons have recently been shown to enhance tumor antigen expression, including carcinoembryonic antigen (CEA), on the surface of human carcinoma cells, which results in an increase in the targeting of antitumor monoclonal antibodies (MAb) in vivo. We report here the effect of recombinant human gamma-interferon (HuIFN-gamma) on the expression of human CEA and its related transcripts in several human colon carcinoma and normal human fibroblast cell lines. The colon tumor cell lines HT-29, WiDr, and LS-174T were each shown to express different constitutive levels of CEA glycopeptide, as measured by the binding of the CEA-specific MAb COL-4. Treatment with HuIFN-gamma enhanced the level of binding of COL-4 in total cell extracts of HT-29 and WiDr cells 2.5- and 6.5-fold, respectively. Using a CEA complementary DNA probe, this increase in MAb binding was shown to be accompanied by a 6- to 11-fold increase in the steady state levels of three CEA transcripts with sizes of 4.2, 3.5, and 2.8 kilobases. On the other hand, HuIFN-gamma treatment had no effect on the level of COL-4 binding or expression of CEA transcripts in LS-174T colon carcinoma cells, which are high constitutive expressors of CEA glycoprotein. Normal human fibroblast cell lines MRC-5 and WI38 had no detectable cytoplasmic CEA glycopeptide levels nor did they contain detectable levels of CEA mRNA, either before or after treatment with HuIFN-gamma. In contrast, HuIFN-gamma induced the de novo expression of the normal major histocompatibility complex class II antigen, HLA-DR, on HT-29 and WiDr colon cancer cells as well as the two fibroblast cell lines. Treatment of the LS-174T cell line with HuIFN-gamma did not result in the induction of class II HLA-DR antigen. These observations suggest that some common factors may be involved in the regulation of the CEA and class II histocompatibility genes. In addition, the demonstration that HuIFN-gamma enhances CEA expression in some carcinoma cell lines but fails to induce de novo expression of CEA transcripts in fibroblasts supports the potential application of HuIFN-gamma in enhancement of tumor targeting of antitumor MAbs and adds to our understanding of the mechanism of gamma-interferon-mediated up-regulation of some tumor antigens.

Cytokeratins in different types of human lung cancer as monitored by chain-specific monoclonal antibodies.

The expression of cytokeratins (CKs) in human lung cancer was studied using chain-specific monoclonal antibodies to CKs 4, 7, 8, 10, 13, 18, and 19. When applied to adenocarcinomas (ACs) of the lung, high levels of CKs 7, 8, 18, and 19 were detected in all tumors, while CK 4 was found in high concentrations in some ACs. CK 10 and 13 were completely absent, or only present in low numbers of cells. Small cell lung cancers (SCLCs) and lung carcinoids contained CK 18 and sometimes 8 and 19, but no CK 7 in most cases. Three out of four tumors, histologically classified as SCLC, and expressing CK 7 in a variable number of cells were found by electron microscopic studies to contain regions with AC and/or squamous cell carcinoma (SQC) differentiation. The monoclonal antibody specific for CK 7 can therefore possibly help to distinguish AC differentiation within SCLC. CKs 10 and 13 were completely absent in SCLCs and lung carcinoids, while few CK 4-positive cells were found in some SCLCs and in one lung carcinoid. Within SQCs the monoclonal antibodies revealed a pronounced heterogeneity in CK expression. CKs 4, 7, 8, 10, 13, 18, and 19 could be detected, although not evenly distributed among all tumor cells. Highly differentiated SQCs expressed high levels of the CKs specific for squamoid differentiation, i.e., CKs 4, 10, and 13 in variable numbers of cells. With decreasing histologically detectable SQC differentiation these markers were gradually lost, while the number of cells containing CKs 7, 8, 18, and 19 increased. Application of this panel of monoclonal antibodies can therefore distinguish not only the main subtypes of lung cancer, but can also indicate the degree of differentiation and the degree of heterogeneity. These findings can be used as a diagnostic aid in lung tumor pathology, which may have an impact on treatment and prognosis.

Steroid receptors in epithelial ovarian carcinoma: relation to clinical parameters and survival.

Estrogen receptor (ER) and progestin receptor were measured in samples of tumors obtained at first laparotomy from 97 previously untreated patients suffering with a primary ovarian epithelial tumor, for whom a 3-year follow-up was available. The presence or absence of steroid receptors (threshold arbitrarily fixed at 10 fmol/mg of cytoplasmic protein) was determined by the dextran coated charcoal method and related to a number of patient characteristics such as the residual disease (cutoff, 2 cm), histological type, International Federation of Gynecologists and Obstetricians grade and stage, and age. Results were analyzed by univariate and multivariate methods. (a) The tumor ER positivity was associated with better survival; progestin receptor showed a similar trend but did not reach statistical significance. (b) After stratification for residual tumor the association ER positivity/better survival was still statistically significant in the subset of patients with residual tumor greater than 2 cm. (c) When the median survival times were considered it became apparent that progestin receptor absence nullified the effect associated with positive ER. (d) Multivariate analysis confirmed that among the variables considered the main determinants of prognosis were the size of the residual tumor, serous histological type, and positive ER.

A Mr 58,000 glycoprotein specifically expressed in developing hamster pancreas and reexpressed in hamster and human pancreatic carcinomas.

A glycoprotein with a molecular weight of 58,000 specifically expressed in exocrine hamster fetal pancreas was characterized using a monoclonal antibody (Mab B4). By immunoperoxidase, Mab B4 stained pancreatic tissue from the 10th day of gestation (6 days before delivery) until the 10th day after birth. The maximal expression of the Mab B4-specific protein called fetal pancreatic (FP) protein was reached between delivery and the 5th day of postnatal life. Endocrine pancreas was negative at any developmental stage. All adult pancreata examined were negative. Moreover, Mab B4 was tested against a wide variety of fetal and adult tissues; only immature pancreata were stained. Chemically induced pancreatic carcinomas were strongly stained by this Mab. On the contrary, other tumors (liver and kidney) appearing simultaneously with pancreatic carcinomas were negative. Using a nitrocellulose immunofixation assay, FP protein was found in all sera from hamsters bearing pancreatic tumors (23 cases tested). This protein was not detected in normal sera. Mab B4 cross-reacted with a protein in human fetal pancreas extracts, that behaves similarly to the hamster FP protein: it is present exclusively in exocrine fetal pancreas and is reexpressed in pancreatic adenocarcinomas. The high tissue specificity of this protein, its oncofetal character, and release into the blood circulation make the FP protein a potential tumor marker of pancreatic cancer.

Cadherin cell-adhesion molecules in human epithelial tissues and carcinomas.

Two distinct calcium-sensitive cell-cell adhesion molecules were identified in human epithelial tissues and carcinomas using two monoclonal antibodies raised against vulvar epidermoid carcinoma A-431 and human mammary carcinoma MCF-7 and selected on the basis of their activities to disrupt cell-cell adhesion. In immunoblot analysis, these antibodies, designated NCC-CAD-299 and HECD-1, detected main bands of Mr 118,000 and 124,000, respectively. Purified tryptic fragments of the antigen recognized by NCC-CAD-299 showed cross-reactivity with a rabbit antiserum against mouse P-cadherin, indicating that this molecule was the human homologue of P-cadherin. On the other hand, the antigen recognized by HECD-1 showed essentially the same tissue distribution pattern as E-cadherin in the mouse, suggesting that this molecule is the human homologue of E-cadherin. Availability of these monoclonal antibodies to human P- and E-cadherin allowed us to examine their distributions in human tissues immunohistochemically. Both antigens were detected in epithelial tissues, but they showed distributions that were distinct from each other. The antigen recognized by HECD-1 was expressed in almost all epithelial tissues, while distribution of the other one recognized by NCC-CAD-299 was restricted to the basal or lower layers of stratified epithelia in which both antigens were coexpressed. Moreover, immunohistochemical examination of 44 lung carcinomas showed that both molecules were coexpressed in all of them, and suggested that expression of P-cadherin was closely related to the differentiation of carcinoma cells.

Phytosterols and cholesterol in malignant and benign breast tumors.

Tissue phytosterol and cholesterol levels in 10 benign and 8 malignant breast tumors were quantitated to reexamine the hypothesis that malignant tumors had distinctive phytosterol content. Phytosterols were present in 9 of 10 benign and 7 of 8 malignant breast tumors. Mean (+/- S.E.) cholesterol, campesterol, stigmasterol, and beta-sitosterol in malignant and benign tumors (microgram/g wet weight) did not significantly differ (p greater than 0.1): (formula: see text) In the malignant tumors, tissue cholesterol correlated with campesterol (r = 0.97) and beta-sitosterol (r = 0.97) (p less than 0.01), but not stigmasterol (r = -0.06). In benign tumors, tissue cholesterol correlated with campesterol (r = 0.43), stigmasterol (r = 0.64), and beta-sitosterol (r = 0.94), with p less than 0.01 for the latter two. Phytosterols were present in four samples of normal breast tissue with mean (+/- S.E.) campesterol, stigmasterol, and beta-sitosterol (2 +/- 0.8, 15 +/- 9, 7 +/- 5 microgram/g wet weight) slightly but not significantly lower than in benign and malignant breast tumors, p greater than 0.1. The comparability of tissue phytosterols in benign and malignant breast tumors and in normal breast tissue appears to render unlikely and putative etiological relationship between phytosterols and breast carcinoma.

Immunohistochemical localization of ganglioside GD3 in human malignant melanoma, epithelial tumors, and normal tissues.

The specific tissue distribution of melanoma-associated ganglioside II3-alpha-N-acetylneuraminosyl-alpha 2----8-N-acetylneuraminosyllactosylceramide (GD3) was studied on 175 cryopreserved, unfixed human tissue sections with R-24 mouse monoclonal antibody by indirect immunoperoxidase staining. A striking specificity of monoclonal antibody R-24 for malignant melanoma tissues was established. Ganglioside GD3 was detected in all 21 tissue sections of 21 patients with primary melanoma and in all 37 probes of 24 patients with metastatic malignant melanoma. The majority of tumor cells in the samples of primary malignant melanoma expressed GD3; however, GD3 expression was more heterogeneous in samples of metastatic lesions even in different metastases of the same patient. Of 11 nevi, 9 reacted with monoclonal antibody R-24, while melanocytes in the basal layer of normal skin stained only weakly and irregularly. None of the 32 normal and 12 fetal human tissue types were R-24 positive, but a strong cytoplasmic staining was observed with single cells in the dermis and in the interstitial tissue of the gastrointestinal tract, in the interlobular septa of the thymus, and in other distinct locations. Only two malignant carcinoid tumors of 38 nonmelanomatous tumors tested reacted with monoclonal antibody R-24.