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M F Bourgeade

Publications and source records attributed to M F Bourgeade.

33 records · Page 2Linked to original sources
PubMed1984

Induction of 2',5'-oligoadenylate synthetase by retinoic acid in two transformed human cell lines.

2',5'-Oligoadenylate (2-5A) synthetase, which polymerizes adenosine triphosphate into 2-5A, is induced upon treatment of cells with interferon (IFN) and is thought to be involved in its antiviral and anticellular action. We report here that retinoic acid (RA) enhanced the level of this enzyme in two human transformed cell lines, WISH and Namalva. Like IFN, RA induced 2-5A synthetase activity in a time- and dose-dependent manner. Addition of anti IFN-alpha, -IFN-beta, or -IFN-gamma antibodies to the medium concomitantly with RA did not prevent such induction; therefore, the effect of RA is clearly not mediated through the induction and externalization of IFN. Pretreatment of cells with actinomycin D inhibited 2-5A synthetase induction by RA, suggesting that RA increased the transcription of the 2-5A synthetase gene. In WISH cells, the growth of encephalomyocarditis virus was inhibited by RA treatment, which is consistent with the hypothesis that 2-5A synthetase plays an important role in the antiviral action of IFN, at least in encephalomyocarditis virus replication. When the anticellular effects of IFN and RA were compared to their ability to induce 2-5A synthetase activity in four human cell lines, there was no strict correlation between the amplitude of the enzyme activity induced and the extent of the antiproliferative effect. It is concluded that the 2-5A system is probably not the only pathway responsible for the antiproliferative effect of both substances. We further suggest that the induction of 2-5A synthetase by IFN and RA might be connected with at least some of the similarities observed between other biological effects of both compounds.

2',5'-Oligoadenylate Synthetase↗
PubMed1983

Interferon affects intracellular calmodulin levels.

Interferon lowers calmodulin levels in two cell lines sensitive to its antiproliferative effect. Further, in synchronized cells, interferon strongly inhibits the increase in calmodulin observed when control cells enter the S phase, and concomitantly inhibits DNA synthesis. Calmodulin has been implicated in the control of cell proliferation and an increase in this protein seems to be necessary for the progression of cells into the S phase of the cell cycle. Therefore, the effect of interferon on calmodulin content might constitute part of the molecular mechanism by which interferon inhibits DNA synthesis.

Animals↗
PubMed1982

Interferon increases HLA synthesis in melanoma cells: interferon-resistant and -sensitive cell lines.

We report that human leukocyte interferon preparations increase the expression of beta 2-microglobulin by 100-200% on the surface of normal fibroblast and melanoma cell lines sensitive to interferon. This increase in expression can be correlated with an increase in HLA synthesis as measured by incorporation of [35S]methionine in these antigens. This enhanced HLA synthesis, which is 5- to 17-fold, is time dependent and dose related. Synchronized cells in the G0/G1 phase of the cell cycle appear to be more sensitive to this interferon action. Neither an increase in surface expression nor in HLA synthesis is observed in a melanoma cell line resistant to the antiviral and antigrowth effects of interferon. Furthermore, there appears to be a stronger correlation between this increased HLA synthesis and the antiviral function than between it and the antiproliferative action of interferon.

Cell Division↗
PubMed1981

Reorganization of the cytoskeleton by interferon in MSV-transformed cells.

beta and gamma interferons were found to enhance the organization of microfilaments, intermediate filaments, and fibronectin in the murine sarcoma virus (MSV)-transformed cell line. Furthermore, both interferons increased the number of intermediate-type junctions. Sodium butyrate was also found to act in a similar way and, when associated with interferon, an additive effect was observed. In the cell line, cultured for many passages in the presence of beta interferon (MSV-IF+), the cytoskeletal network and the extra-cellular matrix were highly developed and were reminiscent of a normal cell. These results could explain some of the biological actions of interferon, such as increased cell adhesion to the substratum and decreased cell motility.

Actins↗
PubMed1980

Type I and type II interferons: differential antiviral actions in transformed cells.

In transformed mouse embryo cells, type II interferon had much less antiviral activity than type I interferon. In non-transformed cells, the two interferons had similar high activity, Reversal of the phenotype of Moloney sarcoma virus (MSV) transformed cells by sodium butyrate restored their sensitivity to the antiviral action of type II interferon. Additional evidence for a role of the cytoskeletal network in the action of type II interferon is that its antiviral effect is reduced by cytochalasin B, colchicine or vinblastine. MSV-transformed cells, selected for their resistance to the antiviral action of type I interferon, were sensitive to type II interferon. These differences in the effects of type I and II interferon on transformed cells are at present unexplained, but suggest that they have at least partially separate mechanisms of action.

Animals↗
PubMed1979

Enhancement of interferon antitumor action by sodium butyrate.

Sodium butyrate together with interferon enhances the antitumor effect of interferon in vivo. When Sarcoma 180 TG cells are inoculated in mice, the mean survival time and final survival rate are greatly increased compared to those for treatment with interferon alone. Similarly, a significant delay in the mean survival time is observed when mice inoculated with L1210 cells are treated with sodium butyrate and interferon. This effect could be due at least in part to a potentiation of interferon action on the tumor cells.

Animals↗