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Biomedical subjects

S Pestka

Publications and source records attributed to S Pestka.

At least 145 records · Page 8Linked to original sources
PubMed1986

Binding of human alpha-interferons to natural killer cells.

It has previously been shown that recombinant DNA-derived human leukocyte interferon IFN-alpha J, which is active on human cells in antiviral and antiproliferative assays, substantially lacks the ability of other purified leukocyte IFN (e.g., IFN-alpha A) to enhance natural killer (NK) activity. IFN-alpha J can, however, block the boosting of NK activity by IFN-alpha A, suggesting that IFN-alpha J can occupy the IFN-alpha receptor on NK cells. We demonstrate here directly that IFN-alpha J can bind to NK cells and can compete with [125I]IFN-alpha A for binding sites. The equilibrium dissociation constant (Kd) for IFN-alpha J is no more than 20-30 times greater than for IFN-alpha A. The relative Kd values for IFN-alpha A and IFN-alpha J are similar when measured with Daudi cells, where both IFN-alphas have potent antiproliferative effects. This suggests that the difference in receptor binding on NK cells in terms of equilibrium binding constants does not explain the inactivity of IFN-alpha J relative to IFN-alpha A on NK cells following a 2-h incubation.

Dose-Response Relationship, Drug↗
PubMed1986

Differential effects of recombinant human leukocyte interferons on cell surface antigen expression.

Human leukocyte (alpha) interferon (IFN-alpha) is composed of a multigene family within which at least eight different species have been expressed in Escherichia coli, isolated, and shown to exert a wide range of biological activities on different human target cells. In this study we utilized eight species of IFN-alpha (A, B, C, D, F, I, J, and K) and investigated their respective capabilities to alter the proliferation of a human breast carcinoma cell line (MCF-7). The antigens studied were all constitutively expressed on the MCF-7 cell surface: the Mr 180,000 carcinoembryonic antigen; a high molecular weight (greater than 10(6] glycoprotein, termed tumor-associated glycoprotein 72; and a major HLA histocompatibility antigen. The level of expression of each antigen was measured by the binding of monoclonal antibodies B1.1, B72.3, and W6/32, respectively. A high degree of diversity was found among the various IFN-alpha species with respect to their ability to enhance antigen expression and inhibit MCF-7 cell growth. The two most potent species, IFN-alpha A and IFN-alpha B, were found to increase the expression of tumor antigens as well as the HLA determinant by 2-5-fold. In contrast, IFN-alpha D and IFN-alpha J were virtually inactive in altering antigen expression but did inhibit the growth of MCF-7 cells. The remaining IFN-alpha species, -alpha C, -alpha F, -alpha I, and -alpha K, exerted an intermediate range of activities for both antigen enhancement and inhibition of MCF-7 cell growth. The relative ability of each species of IFN-alpha to inhibit MCF-7 cell growth appeared to be independent of their effectiveness in augmenting antigen expression. IFN-alpha D and IFN-alpha J, the two species that failed to alter tumor antigen expression, did, however, seem to interact with the interferon receptor since they inhibited MCF-7 cell growth and competed with other IFN-alpha species for the increase in carcinoembryonic antigen, tumor-associated glycoprotein 72, or HLA expression. A comparison of the concentrations of each IFN-alpha necessary to enhance antigen expression revealed that the surface HLA determinant was approximately 10-fold more sensitive to enhancement than was the tumor antigen, carcinoembryonic antigen. The individual members of the IFN-alpha family thus differ extensively in their ability to alter the level of antigen expression on the surface of MCF-7 breast carcinoma cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1985

Differential responsiveness of cloned mammary carcinoma cell populations to the human recombinant leukocyte interferon enhancement of tumor antigen expression.

We have previously shown that a recombinant human leukocyte interferon (IFN-alpha A)5 can mediate an increase in cell surface tumor antigen expression in human carcinoma cells but not normal cells (Greiner et al., 1984). Such a biological response modifier may prove useful in circumventing the problem of antigenic heterogeneity and could increase the effectiveness of monoclonal antibodies (MAbs) for detection and/or therapy of human carcinoma lesions. These studies also revealed that, within populations of human carcinoma cells, there exist subpopulations which are unresponsive to the antigen-enhancing properties of IFN-alpha A. Utilizing cloned cell populations from the MCF-7 human breast carcinoma cell line, we now report the differential responsiveness to the tumor antigen enhancing and antiproliferative actions of IFN-alpha A. Binding of MAb B72.3 to the 220-400 kd tumor antigen, TAG-72, is increased by IFN-alpha A treatment on the surface of the parental MCF-7 cell line and 2 cloned cell populations. A third MCF-7 clone does not express this antigen either before or after IFN-alpha A treatment, but does express a 90 kd tumor antigen and carcinoembryonic antigen which bind MAbs B6.2 and B1.1, respectively. The level of expression of these 2 surface tumor antigens remained unchanged upon interferon treatment. The growth of the parental MCF-7 cells and the 3 cloned cell lines was, however, inhibited by IFN-alpha A. These cell lines also exhibited approximately the same number of interferon receptors with similar binding affinities for IFN-alpha A. The results demonstrate a dissociation of two biological actions of IFN-alpha A-antiproliferative activity and enhancement of tumor antigen expression within a cloned human carcinoma cell line. Our studies also indicate that the differential response of cloned MCF-7 cells to tumor antigen modulation by interferon involves alterations in the transduction of signals occurring distal to receptor occupancy within the biochemical pathways responsible for the actions of this biological response modifier. In addition, the clonal cell lines we have isolated which differ in their responsiveness to interferon should prove valuable in analyzing the molecular basis of interferon actions and may provide insights into the mechanism by which this compound confers its antitumor activity.

Antibodies, Monoclonal↗
PubMed1985

Recombinant human interferon sensitizes resistant myeloid leukemic cells to induction of terminal differentiation.

Recombinant human leukocyte interferon (IFN-alpha A) inhibits growth of the human promyelocytic leukemic cell line HL-60 without inducing these cells to differentiate terminally. When IFN-alpha A is combined with agents capable of inducing differentiation in HL-60 cells, such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA), cis or trans retinoic acid (RA) or dimethylsulfoxide (DMSO), growth suppression and induction of differentiation are dramatically increased. By growing HL-60 cells in increasing concentrations of TPA, RA, or DMSO, a series of sublines have been developed which are resistant to the usual growth inhibition and induction of differentiation seen when wild type HL-60 cells are exposed to these agents. Treatment of these resistant HL-60 cells with the combination of IFN-alpha A and the appropriate inducer results, however, in a synergistic suppression in cell growth and a concomitant induction of terminal differentiation. The ability of interferon to interact synergistically with agents which promote leukemic cell maturation may represents a novel means of reducing resistant leukemic cell populations.

Cell Differentiation↗
PubMed1985

Characterization of receptors for immune interferon in U937 cells with 32P-labeled human recombinant immune interferon.

Recombinant human immune interferon (HuIFN-gamma) was labeled with [gamma-32P]ATP and cyclic-AMP-dependent protein kinase from bovine heart to a specific radioactivity of 11,000 Ci/mmol. At least two molecules of phosphate were incorporated per molecule of interferon. The binding of [32P]HuIFN-gamma to human U937 histiocytic lymphoma cells was time dependent, and displaceable by HuIFN-gamma but not by HuIFN-alpha A or HuIFN-beta. The specific binding was saturable with less than 10% nonspecific binding. The dissociation constant of [32P]HuIFN-gamma for U937 interferon receptors was calculated to be 1.5 X 10(-10) M with a total of 1,800 binding sites/cell. Dissociation of bound [32P]IFN-gamma at 24 degrees C exhibited two distinct rates. A fast dissociation with a specific rate constant of 0.141 min-1, and a slow dissociation with a specific rate constant of 0.0027 min-1. The Kd for [32P]HuIFN-gamma was calculated from kinetic constants to be 5.4 X 10(-10) M.

Binding, Competitive↗
PubMed1985

Effects of combined treatment with interferon and mezerein on melanogenesis and growth in human melanoma cells.

We have analyzed the effects of various human interferons produced in bacteria and the antileukemic compound mezerein (MEZ) on growth and melanogenesis in human melanoma cells. In four human melanoma cell lines, recombinant human fibroblast interferon (IFN-beta) was more active than recombinant human leukocyte interferons (IFN-alpha A, IFN-alpha D, or IFN-alpha A/D (Bgl] in inhibiting cellular proliferation. When monolayer cultures were exposed to 1000 IU/ml IFN-beta for four days the degree of growth inhibition in the different melanoma cell lines varied between 94 and 26%. Similarly, four days growth in medium containing 10 ng/ml MEZ resulted in either no inhibition of growth or as much as 53% inhibition of growth, depending on the specific melanoma cell line tested. MEZ induced dendrite-like processes, cytoplasmic projections morphologically similar to those normally found in neurons and melanocytes, in all four melanoma cell lines, whereas none of the interferons tested had this effect. The combination of interferon and MEZ resulted in a dramatic inhibition in cellular proliferation in all four melanoma cell lines. When cell extracts were assayed for melanin content, a marker of melanoma cell differentiation, the combination of IFN-beta and MEZ resulted in higher levels of melanin than with either agent alone. Dendrite-like formation was also prominent in the cultures treated with this combination. These results indicate that the antiproliferative effect of interferon toward human melanoma dells can be enhanced by treatment with MEZ and that this effect is associated with an enhancement of terminal differentiation.

Antineoplastic Agents, Phytogenic↗
PubMed1985

Changes in binding of alpha interferon IFN-alpha A to HL-60 cells during myeloid differentiation.

The differentiation of human leukemic HL-60 cells from their predominantly promyelocyte form to a neutrophil-like state can be induced by the addition of dimethylsulfoxide (DMSO) or retinoic acid (RA) to the growth medium. The binding of human recombinant interferon IFN-alpha A to the undifferentiated and differentiated HL-60 cells was investigated. Within 2 days after the addition of DMSO or retinoic acid to growing HL-60 cells, the binding of IFN-alpha A to treated cells increases significantly relative to its binding to untreated cells. The difference in binding of IFN-alpha A between the treated and untreated cells continues to increase for at least 3 days. Analysis of binding curves of IFN-alpha A to neutrophil-like and promyelocytic HL-60 cells leads to the conclusion that the increased binding of [125I]IFN-alpha A to neutrophil-like cells is primarily the result of an increase in the number of binding sites on these cells.

Cell Differentiation↗
PubMed1984

Monoclonal antibodies to breast cancer-associated antigens as potential reagents in the management of breast cancer.

Monoclonal antibodies reactive with the surface of human breast carcinoma cells have been generated and characterized. The immunogens used were membrane-enriched fractions of metastatic carcinoma lesions. The various monoclonals were shown to react with previously known as well as with novel tumor-associated antigens (TAAs). The most specific of the latter group is monoclonal B72.3, which is reactive with a 220,000 to 400,000 high-molecular-weight glycoprotein complex found in 50% of human mammary carcinomas and 80% of human colon carcinomas. Monoclonal antibody B6.2, which recognizes a 90,000-d glycoprotein, was radiolabeled and shown to efficiently localize human carcinoma transplants in athymic mice via gamma imaging without the use of second antibody or background subtraction manipulations. F(ab')2 and Fab' fragments were shown to be more efficient for tumor localization than intact immunoglobulin. Whereas the phenomenon of antigenic heterogeneity of tumor cell populations has long been known to exist, this phenomenon was also shown to manifest itself as antigenic modulation, in which specific TAAs can modulate their expression on the cell surface concurrent with different phases of the cell cycle. A phenomenon known as antigen evolution, in which a specific cloned tumor cell population can gradually drift in antigenic phenotype, has also been demonstrated. Recombinant interferon has been employed to (1) enhance the expression of specific TAAs on the surface of tumor cells already expressing the antigen; and (2) induce the expression of specific TAAs on the surface of carcinoma cells not previously expressing the antigen. The clinical implications of such phenomena in gamma scanning for the detection of tumor masses and for tumor immunotherapy are discussed. Methods for circumvention of problems inherent in the clinical use of monoclonal antibodies are also addressed.

Animals↗
PubMed1984

Hybrid recombinant human leukocyte interferon inhibits differentiation in murine B-16 melanoma cells.

We have investigated the effects of recombinant human leukocyte interferons (IFN-alpha A and IFN-alpha D) and various hybrid recombinant human leukocyte interferons on differentiation in B-16 mouse melanoma cells. Inhibition of both spontaneous and melanocyte hormone stimulated differentiation was observed with one hybrid construct, IFN-alpha A/D (Bgl) consisting of amino acids 1 to 62 from IFN-alpha A and amino acids 64 to 166 from IFN-alpha D. In contrast, the parental human interferons, IFN-alpha A and IFN-alpha D, when used alone or in combination, as well as other hybrid human leukocyte interferons, did not cause significant inhibition of melanogenesis in B-16 mouse cells. The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) also inhibited B-16 differentiation and the combination of TPA with IFN-alpha A/D (Bgl) or mouse L-cell interferon was synergistic in delaying melanogenesis. These studies indicate that the IFN-alpha A/D (Bgl) hybrid that exhibits antiviral activity on mouse cells can also inhibit differentiation of murine cells.

Animals↗
PubMed1984

Some species of human leukocyte interferon are glycosylated.

The carbohydrate content of all of the species of human leukocyte interferon (IFN-alpha) which have been derived from patients with chronic myelogeneous leukemia (CML) and purified to homogeneity has now been determined. Amino sugar content was measured by high-performance liquid chromatography and fluorescamine detection of acid hydrolysates of each sample. Two species showed significant amounts of glucosamine. Most of the purified species of leukocyte interferon from a myeloblast cell line were also tested, and two species were found to contain sugar residues. These forms also differed from the CML interferons in that they revealed the presence of greater amounts of galactosamine. The apparent lack of carbohydrate in some of the higher-molecular-weight species of interferon implicated factors other than glycosylation in the molecular weight differences. The results indicate that some species of IFN-alpha are glycosylated to various degrees.

Amino Sugars↗
PubMed1984

A species of human alpha interferon that lacks the ability to boost human natural killer activity.

Most species of recombinant leukocyte interferons (IFN-alpha A, -alpha B, -alpha C, -alpha D, -alpha F, -alpha I, and -alpha K) were capable of boosting human natural killer (NK) activity after a 2-hr treatment of cells at a concentration of 1-80 units/ml. In contrast, recombinant human IFN-alpha J was found to be incapable of augmenting NK activity after exposure of cells for 2 hr to concentrations as high as 10,000 units/ml. This inability of IFN-alpha J to boost NK activity was not complete because, after exposure of cells to a high concentration of IFN-alpha J (10,000 units/ml) for 18 hr, boosting of cytolysis was observed. IFN-alpha J appeared to interact with receptors for IFN on NK cells since it was found to interfere with the boosting of NK activity by other species of IFN-alpha. In contrast to its deficient ability to augment NK activity, IFN-alpha J has potent antiviral and antiproliferative activities. Such extensive dissociation of these biological activities has not been observed previously with any other natural or recombinant IFN species. Thus, this IFN species may be useful for evaluating the relative importance of various biological activities on the therapeutic effects of IFN, for understanding structure-function relationships, and for determining the biochemical pathways related to the various biological effects of IFN.

Amino Acid Sequence↗
PubMed1984

Anti-mRNA: specific inhibition of translation of single mRNA molecules.

A plasmid was constructed to generate RNA complementary to the beta-galactosidase mRNA under control of the phage lambda PL promoter. When this anti-mRNA was produced, synthesis of beta-galactosidase was dramatically inhibited (98%). Syntheses of galactoside permease and transacetylase, whose coding sequences are downstream of the beta-galactosidase coding region, are inhibited to a lesser degree, 80% and 55%, respectively. The generation of anti-mRNA that can be targeted to inhibit a single species of mRNA molecule within cells provides a potent mechanism by which specific transcripts can be translationally inactivated. This can be used to determine the function of proteins as well as to select cloned genes in a single rapid and convenient step.

Acetyltransferases↗