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Biomedical subjects

C M Boyer

Publications and source records attributed to C M Boyer.

At least 19 recordsLinked to original sources
PubMed1992

Fibronectin is an immunosuppressive substance associated with epithelial ovarian cancer.

BACKGROUND: Although the ascites of patients with ovarian cancer has been reported to contain immunosuppressive factors, the identity and source of this activity has not been determined. Previously, the authors showed that conditioned media from two of four epithelial ovarian cancer cell lines inhibits proliferation of mitogen-stimulated human lymphocytes. The physical characteristics of the inhibitory substance are unlike those of peptide growth factors but closely resemble those of fibronectin. METHODS AND RESULTS: In the current study, it was found that the two ovarian cancer cell lines that produce the inhibitory substance have more fibronectin on the cell surface and secrete significantly more immunoreactive fibronectin into their culture media than the other two ovarian cancer cell lines. In addition, the immunosuppressive activity was bound to a gelatin-Sepharose affinity column, known to bind fibronectin. Finally, in ascites from 20 patients with advanced epithelial ovarian cancer, fibronectin levels correlated with the ability to inhibit proliferation of lectin-stimulated lymphocytes (P < 0.001). CONCLUSIONS: Fibronectin is produced by some ovarian cancer cell lines and acts to inhibit proliferation of mitogen-stimulated lymphocytes. Additional studies are needed to clarify the role of fibronectin in ovarian cancer.

Ascites↗
PubMed1992

A combination of two immunotoxins exerts synergistic cytotoxic activity against human breast-cancer cell lines.

In previous studies, combinations of immunotoxins reactive with different cell-surface antigens have exerted additive cytotoxicity against tumor cells in culture. In this report we describe a combination of 2 immunotoxins that produce synergistic cytotoxic activity. Recombinantly derived ricin A chain (RTA) was conjugated with murine monoclonal antibodies (MAbs) 317G5, 260F9, 454A12 and 741F8 that bound to cell-surface determinants of 42, 55, 180 (transferrin receptor) and 185 kDa (HER-2/neu) expressed by the SKBr3 human breast-cancer cell line. When inhibition of clonogenic growth was measured in a limiting dilution assay, the combination of 260F9-RTA and 454A12-RTA produced synergistic cytotoxic activity against SKBr3 and 2 other breast-cancer cell lines. All other combinations produced only additive inhibition of clonogenic growth. Simultaneous binding of 260F9 and 454A12 was not supra-additive, but sub-populations of cells which lacked one or the other antigen could be detected. Kinetic studies of internalization, using antibodies conjugated with gold particles, indicated that 454A12 remained within peripheral endosomes for a longer interval in the presence of 260F9. This change in the traffic of the transferrin receptor may contribute to synergy between 260F9-RTA and 454A12-RTA.

Antibodies, Monoclonal↗
PubMed1992

Stimulation of ovarian tumor cell proliferation with monocyte products including interleukin-1, interleukin-6, and tumor necrosis factor-alpha.

OBJECTIVE: We investigated whether monocyte-derived factors could stimulate the growth of ovarian cancer cells. STUDY DESIGN: Human peripheral blood monocytes or human monocyte-like cell lines THP-1 and U-937 were cultured with or without macrophage colony-stimulating factor, lipopolysaccharide, or phorbol myristate acetate. Culture supernatants or recombinant cytokines were assayed for growth stimulation of ovarian cancer cell lines by tritium-thymidine incorporation and direct cell counts followed by statistical analysis with Student t test. RESULTS: Conditioned medium from peripheral blood monocytes or from THP-1 or U-937 cells stimulated ovarian cancer cell growth. Interleukin-1 alpha, tumor necrosis factor-alpha, and interleukin-6 also stimulated ovarian cancer cell growth, whereas macrophage, granulocyte, and granulocyte-macrophage colony-stimulating factor did not. Concentrations of tumor necrosis factor, interleukin-1, and interleukin-6 in conditioned medium could not account for all the growth stimulation, and activity remained after neutralization of tumor necrosis factor, interleukin-1, and interleukin-6 with antibodies. CONCLUSIONS: Interleukin-1, interleukin-6, tumor necrosis factor, and additional monocyte factor(s) could provide paracrine growth stimulation when monocytes are attracted to ovarian cancers that produce macrophage colony-stimulating factor.

Cell Division↗
PubMed1991

Requirements for the internalization of a murine monoclonal antibody directed against the HER-2/neu gene product c-erbB-2.

A murine monoclonal antibody, TA1, is directed against an epitope on the extracellular domain of the HER-2/neu (c-erbB-2) gene product. Requirements for TA1-induced internalization of c-erbB-2 have been studied using the SKBr3 human breast cancer cell line and several rat fibroblast cell lines that express either wild-type or mutant human c-erbB-2. Internalization of TA1 was monitored by assaying protease-resistant uptake of 125I-labeled TA1, by electron microscopy of gold-labeled TA1, and by inhibition of clonogenic growth of cells incubated with TA1 that had been conjugated with blocked ricin. Similar rates of internalization of TA1 were observed in SKBr3 and in rat fibroblasts that expressed human c-erbB-2. The route of endocytosis was the same as that observed with antibodies against other membrane receptors. Anti-c-erbB-2 and anti-transferrin receptor cointernalized through clathrin-coated pits, coated vesicles, endosomes, and multivesicular bodies. Products of mutant c-erbB-2 that lacked a portion of the tyrosine kinase domain or that lacked most of the cytoplasmic domain were endocytosed in the presence of TA1 as promptly as the wild-type c-erbB-2 product. Slightly more rapid internalization of TA1 was observed in rat cells that expressed c-erbB-2 with a single point mutation in the transmembrane domain. Taken together, our data suggest that neither the intracytoplasmic domain nor receptor phosphorylation is required for antibody-mediated endocytosis of c-erbB-2.

Animals↗
PubMed1991

Cytotoxic T-lymphocytes derived from patients with breast adenocarcinoma recognize an epitope present on the protein core of a mucin molecule preferentially expressed by malignant cells.

A population of tumor-reactive cytotoxic T-cells can be propagated from tumor-draining lymph nodes of patients with breast adenocarcinoma. These T-cells specifically recognize breast and pancreatic tumor cells in a major histocompatibility complex (MHC)-unrestricted fashion but not other tumors of epithelial origin or the natural killer target K562. The tumor-specific but MHC-unrestricted lytic activity of these cytotoxic T-lymphocytes (CTLs) is mediated through the alpha/beta T-cell receptor. The molecule recognized by these CTLs is ductal epithelial mucin produced by breast and pancreatic adenocarcinomas. The protein core of the mucin consists of multiple tandem repeats of a 20-amino acid sequence. Antibody SM3, directed against a determinant on the mucin protein core preferentially expressed on malignant cells is able to significantly inhibit lysis of tumor cells by the CTL, while other antibodies binding to different core epitopes are not. Normal breast epithelial lines, which also express mucin but not the SM3 epitope, are not lysed by these tumor-reactive CTLs or act as cold target inhibitors of lysis of tumor lines. The data suggest that the highly repetitive nature of the mucin allows cross-linking of the T-cell receptor on mucin-specific T-cells and therefore accounts for the lack of MHC restriction seen in this system. They further suggest that the mucin core epitope recognized on tumor cells is not expressed on normal epithelial cells in a manner that can be recognized by tumor-reactive CTLs. These findings support the role of mucins as important tumor-associated antigens mediating the cellular response to certain human cancers and suggest that epithelial mucin core sequences might form the basis for an effective vaccine to augment the antitumor immune response.

Adenocarcinoma↗
PubMed1991

Expression and amplification of the HER-2/neu (c-erbB-2) protooncogene in epithelial ovarian tumors and cell lines.

Amplification of the c-erbB-2 protooncogene has been associated with a poor prognosis in human breast and ovarian cancers. Our study was undertaken to examine whether amplification, rearrangement, or overexpression of c-erbB-2 and other protooncogenes was frequently observed in epithelial ovarian cancers. c-erbB-2 was expressed in 87% of 22 ovarian cancers analyzed, but expression was significantly increased in only one of the 22 tumor specimens. In this case elevated c-erbB-2 expression was associated with dramatic amplification of the gene. In another tumor a 3.8 kb EcoRI fragment was found, in addition to the usual 4.4 and 6.0 kb fragments; this is consistent with a possible gene rearrangement or a restriction fragment length polymorphism. To place these results in perspective, expression of several other protooncogenes has been examined in ovarian carcinomas. The c-fos, c-myc, n-myc, c-fms, and c-Ha-ras protooncogenes were expressed in different fractions of tumors, but expression of l-myc, c-erbB, c-myb, c-sis, and c-mos was not detectable. Aside from c-erbB-2, neither amplification nor rearrangement was observed among the other protooncogenes studied. Expression of c-erbB-2, c-fms, c-myc, n-myc, c-fos, and c-Ha-ras deserves further evaluation as a prognostic factor in ovarian cancer.

Female↗
PubMed1990

Use of immunotoxins in combination to inhibit clonogenic growth of human breast carcinoma cells.

Substantial heterogeneity has been observed in the expression of individual antigens within tumor cell populations. Immunotoxins which bind to different cell surface antigens might exert additive or synergistic cytotoxicity when used in combination to eliminate all clonogenic cells within a tumor. Immunotoxins have been prepared by conjugating recombinantly derived toxin A chain to different monoclonal reagents which recognize cell surface determinants of Mr 42,000 (317G5), 55,000 (260F9), and 200,000 (741F8). Each immunotoxin was evaluated for binding, internalization, and cytotoxicity with four breast cancer cell lines. Each of the three immunotoxins bound to the SKBr3 cell line and exerted antitumor activity in a limiting dilution clonogenic assay. Simultaneous treatment with two immunotoxins produced additive antitumor activity with each of the possible combinations. Additive binding could be demonstrated by immunofluorescent techniques, however, with only one of three combinations. With two of the three combinations, subpopulations of tumor cells could be identified which lacked one or the other antigenic determinant but not both. Consequently, log-additive antitumor activity was produced by immunotoxins in combination, and heterogeneity of antigenic targets may have contributed to the combined cytotoxicity in some but not all cases.

Antibodies, Monoclonal↗
PubMed1990

Heterogeneity of antigen expression in advanced epithelial ovarian cancer.

Immunohistochemical techniques were used to evaluate the expression of six antigens (CA 125, TAG 72, CA 19-9, OVTL3, DF3, and transferrin receptor) in frozen sections from the primary tumor and metastases of 20 patients with epithelial ovarian cancer. Heterogeneous expression of most antigens was observed within a given tumor nodule, but in each patient the proportion of cells expressing an antigen was similar in the primary tumor and metastases. To explore the stability of the antigenic phenotype of individual cells, we studied CA 125 expression in an ovarian cancer cell line. Cells were separated into CA 125-positive and -negative groups using fluorescence-activated cell sorting. After the two groups of cells were recultured separately, only 38% of cells originally sorted as CA 125 positive still expressed CA 125, whereas 27% of cells sorted as CA 125 negative expressed CA 125. That cells may gain or lose CA 125 expression in culture suggests that expression of CA 125 by ovarian cancer cells is not a stable trait.

Adenocarcinoma↗
PubMed1990

Induction of HLA-specific CTL to nonimmunogenic, heat-inactivated lymphocytes by interleukin 2.

Human lymphocytes that have been heat-inactivated (1 hr, 45 degrees C) were used as stimulator cells in a model system to study the requirements of allogeneic T cell activation in vitro. Cytotoxic T lymphocytes were not generated in either primary or secondary mixed lymphocyte cultures after exposure to heated stimulator cells. Successful reconstitution of cytolytic activity in primary cultures was achieved by the addition of rIL-2. Further, cytotoxic T cell lines could be maintained in culture for several weeks by stimulation with heated allogeneic cells and periodic addition of exogenous IL-2. The cytotoxic T cells generated in primary cultures or in the T cell lines were specific for the HLA class I antigens of the stimulating cells. Thus, the combination of heated cells and IL-2 stimulated antigen-specific cytotoxic cells, and not merely lymphokine-activated killers. Although IL-2 production appeared to be a crucial missing component of MLCs with heated lymphocytes, the addition of IL-1, a factor known to act as a second signal for stimulating IL-2 production, did not reconstitute cytolytic activity. These results indicate that (1) heat treatment does not appreciably affect class I structure; (2) HLA class I/T cell receptor interactions are intact, resulting in responsiveness to IL-2 but not IL-1; and (3) heating creates a defect that has a minimal effect on CTL precursor activation but does disrupt a T helper cell/stimulator cell interaction critical for IL-2 production.

Histocompatibility Antigens Class I↗
PubMed1990

The role of peptide growth factors in epithelial ovarian cancer.

We studied the effect of epidermal growth factor, platelet-derived growth factor, fibroblast growth factor, and transforming growth factor-beta on proliferation of four epithelial ovarian cancer cell lines (OVCA 420, OVCA 429, OVCA 432, and OVCA 433). Epidermal growth factor stimulated growth of OVCA 429 cells (P = .0001) and OVCA 433 cells (P = .0002). Platelet-derived growth factor did not stimulate growth of any of the cell lines. Fibroblast growth factor stimulated growth of OVCA 420 cells (P = .003). Transforming growth factor-beta inhibited growth of OVCA 420 cells (P = .0001), OVCA 432 cells (P = .003), and OVCA 433 cells (P = .004). To detect production of known growth factors by the cancer cell lines, we tested the effect of cancer cell-conditioned media on proliferation of cell lines known to respond to growth factors. Only media exposed to OVCA 433 cells were found to contain activity that mimicked one of the known growth factors (transforming growth factor-beta). These results suggest that individual ovarian cancers vary widely in their response to and production of known peptide growth factors. Finally, we found that OVCA 429-conditioned medium significantly inhibited proliferation of mitogen-stimulated lymphocytes (P less than .0001). The characteristics of this immunosuppressive factor were distinct from those of transforming growth factor-beta. Production of this factor by an immortalized cell line provides a unique opportunity to identify an immunosuppressive substance associated with ovarian cancer.

Cell Division↗
PubMed1989

Differential induction by interferons of major histocompatibility complex-encoded and non-major histocompatibility complex-encoded antigens in human breast and ovarian carcinoma cell lines.

Treatment of cancer cells with interferons can modulate expression of cell surface antigens, particularly those of the major histocompatibility complex (MHC). To examine the effect of recombinant gamma- and alpha-interferons on expression of non-MHC antigens, murine monoclonal antibodies have been used to quantitate 14 distinct tumor-associated cell surface antigens from five breast cancer cell lines and five ovarian cancer cell lines using a live cell radioimmunoassay. Both Class I and Class II MHC antigens could be augmented or induced with gamma-interferon. Significantly increased expression of MHC antigens was observed in nine of 10 cell lines with induction indices as high as 11-fold. When 17 non-MHC epitopes were measured on 10 cell lines, minimal (1.3-2.7-fold) induction was observed in 10 of the 170 instances evaluated. Expression of only two epitopes, 2G3 and 735B11, was increased on more than one cell line. On six cell lines expression of non-MHC epitopes could not be increased. Consequently, among many different cell surface determinants, interferons produced a highly selective augmentation or induction of MHC antigens, whereas augmentation or induction of other tumor-associated antigens was apparently restricted to a few epitopes.

Antigens, Neoplasm↗
PubMed1989

Immunohistochemical expression of CA 125 in endometrial adenocarcinoma: correlation of antigen expression with metastatic potential.

Immunohistochemical localization of CA 125 using murine monoclonal antibody OC 125 was performed on fresh frozen tissue from 44 endometrial adenocarcinomas and 26 benign endometria. Immunohistochemical evaluation incorporated both intensity and distribution of staining (CA 125 HSCORE). Thirty-seven cancers (84%) and 23 benign endometria (88%) expressed immunohistochemically detectable CA 125. Staining was confined to epithelial cells and was present both on the cell membrane and in the cytoplasm. Among the 44 endometrial cancers, CA 125 HSCORE did not correlate with histological grade, depth of myometrial invasion or estrogen/progesterone receptor levels. Following surgical staging, 13 patients (30%) were found to have extrauterine metastatic disease. The median CA 125 HSCORE of patients with metastatic disease (2.25) was significantly higher than that of patients with disease confined to the uterus (0.6) (P less than 0.001). In addition, high CA 125 HSCORE also correlated with the presence of lymph node metastasis (P less than 0.001). The results of this study suggest that high CA 125 expression by endometrial adenocarcinomas is associated with increased metastatic potential.

Adenocarcinoma↗
PubMed1989

Heterogeneity of antigen expression in benign and malignant breast and ovarian epithelial cells.

Expression of II distinct antigen families has been studied in normal and malignant epithelial cells from breast and ovary by avidin-biotin immunoperoxidase staining of frozen tissue sections. Each of the antigens was expressed in a fraction of the normal and malignant breast tissues from different individuals. Among breast and ovarian cancers, a similar fraction of tumors expressed each of the determinants. An epitope on a 42-kDa glycoprotein was expressed significantly more often by ovarian carcinomas than by benign ovarian epithelium. Several determinants on 66-, 240-kDa or high-molecular-weight proteins or glycoproteins were expressed significantly more often on benign breast epithelium than on normal ovarian epithelium. Substantial heterogeneity in antigen expression was observed among different tumor specimens. Each of 14 epithelial ovarian cancers expressed a distinctive combination of antigens. Among 18 breast cancers, 16 distinct antigenic phenotypes were observed. Interestingly, comparable heterogeneity was observed in the expression of epitopes on benign breast and ovarian epithelium, compatible with the possibility that the monoclonal reagents recognized polymorphic determinants. Substantial variations in antigen expression were also observed among cells within each neoplasm. However, when antibodies against 5 different determinants were used in combination, a majority of cells could be stained intensely in all 13 breast carcinomas tested and more than 95% of tumor cells could be stained in 10 of the 13.

Antigens, Neoplasm↗
PubMed1986

Functional defect of heat-inactivated human lymphocytes in mixed-lymphocyte culture.

Possible causes were examined for the inability of heat-inactivated lymphocytes to induce proliferative responses in mixed-lymphocyte cultures (MLC). Cells heated at 45 degrees C for 60 min lost greater than 90% of their capacity to stimulate in primary (1 degree) or secondary (2 degrees) MLC. This was not due to accelerated or delayed proliferation, nor to a simple quantitative loss of antigen since a 10-fold increase in stimulators or sequential addition of heated stimulators at 4-hr intervals was ineffective. Heated B lymphocytes had approximately 80% expression of HLA-DR and DQ antigens compared to unheated B cells when measured by flow cytometry using monoclonal antibodies detecting both monomorphic and polymorphic antigens. Contrary to some reports, there was no evidence of direct suppression or induction of suppression by heated stimulators or their supernatants. Reconstitution of 1 degree and 2 degrees MLC with crude MLC supernatants or more purified interleukin 1 (Il-1) or interleukin 2 (Il-2) was unsuccessful. The results indicate the heat-induced defect occurs immediately and is not due to direct or indirect suppression, insufficient amounts of Il-1 or Il-2, nor loss of polymorphic Class II HLA determinants. Heat inactivation of stimulator function may result from failure to present an "immunogenic grid" or loss of accessory molecules required in lymphocyte interactions.

B-Lymphocytes↗
PubMed1985

Quantitation of the Sm nuclear antigen in tissues and activated lymphocytes.

Anti-Sm antibodies are specific for the diagnosis of systemic lupus erythematosus both in humans and in mice. Because the autoantibody response to this nuclear ribonucleoprotein particle is probably antigen driven, we have quantitated the Sm antigen in cells and tissues, using a highly sensitive and specific enzyme-linked immunosorbent assay. The Sm content of several in vitro cell lines was determined to be approximately 1 pg of Sm/cell. We found that murine spleen cells stimulated in vitro with either T cell or B cell mitogens contained up to 10 times more Sm than did unstimulated cells and that they also released increased amounts of Sm. In a survey of organs from several mouse strains, we found that lymphoid tissues had the largest amounts of Sm and that the Sm content of a particular tissue correlated with its DNA content. Increased amounts of Sm in and around activated lymphocytes, as found in systemic lupus erythematosus, may provide a source of antigen for the induction of the anti-Sm autoantibody.

Animals↗
PubMed1979

The use of supplemental nurses: why, where, how?

The use of nurses from labor pool agencies is one way of dealing with the ever present problem of maintaining adequate staffing. Although there are benefits in using supplemental nurses, there are also problems which directors of nursing services need to be aware of in order to assure quality nursing care. The author reports the results of a statewide survey of the use of nurses from supplemental staffing agencies.

Evaluation Studies as Topic↗
PubMed1979

Conditions for effective Bacillus Calmette-Guérin immunotherapy of postsurgical metastases of 13762A rat mammary adenocarcinoma.

We evaluated critical variables in Bacillus Calmette-Guérin (BCG) immunotherapy of residual 13762A rat mammary adenocarcinoma. BCG was given intratumorally on Day 7 of tumor growth and followed by primary tumor excisions on Day 20. Untreated animals died on about Day 40 with axillary nodal and pulmonary parenchymal metastases. BCG-treated animals experienced prolonged survival, and some were cured. The highest dose (5.0 X 10(7) colony-forming units) of BCG was more effective than the lowest (0.5 X 10(7) colony-forming units), but 1,500 micrograms Corynebacterium parvum were more effective than even the highest BCG dose. Previous sensitization to BCG did not improve the effects of BCG treatment. BCG treatment was effective when given on Day 7 and sometimes as late as Day 12 or 17, but C. parvum was ineffective if given after Day 7. Repeated injections of BCG or C. parvum were not more effective than single injections were. Rats cured of residual 13762A tumor by BCG treatment were strongly and specifically immune to rechallenge. We concluded that a high dose (5.0 X 10(7) colony-forming units) of BCG given early (7 days) was the most effective presurgical treatment of 13762A metastases. Repeated injections or host presensitization to BCG did not improve the benefits.

Adenocarcinoma↗