Role of interferon in the pathogenesis of virus diseases in mice as demonstrated by the use of anti-interferon serum. I. Rapid evolution of encephalomyocarditis virus infection.

The role of interferon in the pathogenesis of encephalomyocarditis (EMC) virus infection was determined by treating mice with potent, partially purified sheep anti-mouse interferon globulin. In control mice, EMC virus was present in low titers in various visceral organs but attained high titers in the brain towards the 4th to 5th day, at which time mice died with signs of central nervous system disease. In mice treated with anti-mouse interferon globulin, virus was present in high titer in visceral organs 24--36 h after viral inoculation and virtually all mice were dead by 45 h. This rapid evolution of EMC virus infection was not observed in mice treated with the globulin fraction prepared from a normal sheep, from a sheep exhibiting a low anti-mouse interferon-neutralizing titer, nor from a sheep having a high titer of antibody to human leukocyte interferon. The experimental results indicated that anti-interferon globulin neutralized the interferon liberated by virus-infected cells, thus permitting extensive virus multiplication in several visceral organs. We conclude that interferon is an important early component of host resistance to this virus infection.

Detection of a functional hybrid receptor gammac/GM-CSFRbeta in human hematopoietic CD34+ cells.

A functional hybrid receptor associating the common gamma chain (gammac) with the granulocyte/macrophage colony-stimulating factor receptor beta (GM-CSFRbeta) chain is found in mobilized human peripheral blood (MPB) CD34+ hematopoietic progenitors, SCF/Flt3-L primed cord blood (CB) precursors (CBPr CD34+/CD56-), and CD34+ myeloid cell lines, but not in normal natural killer (NK) cells, the cytolytic NK-L cell line or nonhematopoietic cells. We demonstrated, using CD34+ TF1beta cells, which express an interleukin (IL)-15Ralpha/beta/gammac receptor, that within the hybrid receptor, the GM-CSFRbeta chain inhibits the IL-15-triggered gammac/JAK3-specific signaling controlling TF1beta cell proliferation. However, the gammac chain is part of a functional GM-CSFR, activating GM-CSF-dependent STAT5 nuclear translocation and the proliferation of TF1beta cells. The hybrid receptor is functional in normal hematopoietic progenitors in which both subunits control STAT5 activation. Finally, the parental TF1 cell line, which lacks the IL-15Rbeta chain, nevertheless expresses both a functional hybrid receptor that controls JAK3 phosphorylation and a novel IL-15alpha/gammac/TRAF2 complex that triggers nuclear factor kappaB activation. The lineage-dependent distribution and function of these receptors suggest that they are involved in hematopoiesis because they modify transduction pathways that play a major role in the differentiation of hematopoietic progenitors.

Inhibition of cell motility by interferon.

Interferon derived from human leukocytes, human fibroblasts, and mouse fibroblasts was found to inhibit the motility of cultured cells. It inhibits the tumor-induced motility of capillary endothelial cells as well as the spontaneous migration of other cell types. The ability of a given preparation of interferon to inhibit the motility of a given cell type is proportional to its antiviral activity in that particular cell type. Antiserum to human leukocyte interferon neutralizes both the motility-inhibitory activity and the antiviral activity of this preparation.

Interleukin (IL) 4 and IL-13 act on human lung fibroblasts. Implication in asthma.

Airway hyperresponsiveness leading to subepithelial fibrosis is mediated by inflammatory cells activated by T helper (Th) 2-derived cytokines such as IL-4 and IL-5. By analyzing the phenotype and response of human lung fibroblasts derived from either fetal (ICIG7) or adult (CCL202) tissue as well as from a Th2-type stromal reaction (FPA) to IL-4 and IL-13, we provide evidence that human lung fibroblasts may behave as inflammatory cells upon activation by IL-4 and IL-13. We show that the three types of fibroblasts constitute different populations that display a distinct pattern in cell surface molecule expression and proinflammatory cytokine and chemokine release. All fibroblasts express functional but different IL-4/IL-13 receptors. Thus, while IL-4 receptor (R) alpha and IL-13Ralpha1 chains are present in all the cells, CCL202 and FPA fibroblasts coexpress the IL-13Ralpha2 and the IL-2Rgamma chain, respectively, suggesting the existence of a heterotrimeric receptor (IL-4Ralpha/IL-13Ralpha/IL-2Rgamma) able to bind IL-4 and IL-13. Stimulation with IL-4 or IL-13 triggers in the fibroblasts a differential signal transduction and upregulation in the expression of beta1 integrin and vascular cell adhesion molecule 1 and in the production of IL-6 and monocyte chemoattractant protein 1, two inflammatory cytokines important in the pathogenesis of allergic inflammation. Our results suggest that when activated by IL-4 and IL-13, different subsets of lung fibroblasts may act as effector cells not only in the pathogenesis of asthma but also in lung remodeling processes. They may also differentially contribute to trigger and maintain the recruitment, homing, and activation of inflammatory cells.

Fibrin clot retractile activity in normal, established, and tumorigenic human epithelial cells in culture.

Normal and established human epithelial cell lines obtained from the same organs were compared for their capacity to retract a fibrin clot. Fibrin clot retraction was maximal in normal epithelial cells, reduced in established nontumorigenic lines, and lost in tumorigenic cancer cell lines. Fibrin clot retraction efficiency seemed to be related to the degree of cellular spreading within the clot at the end of the test. Previous works and the present study suggest that fibrin clot retraction is correlated with some steps of cell transformation in vitro.

Enhancement of X-ray-induced transformation in C3H/10T1/2 cells by interferon.

Interferon may enhance malignant transformation induced by X-rays in a C3H mouse embryo-derived cell line. The inhibitory effect of interferon on cell division during the proliferative phase of the expression of the transformational damage may be of importance in the understanding of this finding.

Association of phenotypic reversion of transformed cells induced by interferon with morphological and biochemical changes in the cytoskeleton.

The distribution of microfilament bundles, intermediate filaments, microtubules, vinculin plaques, and extracellular fibronectin matrices was examined by indirect immunofluorescence in X-ray-transformed C3H/10T1/2 cells. The transformed phenotype correlated with a lack of actin cables and vinculin-containing plaques. Prolonged treatment of these transformed cells with interferon resulted in a reversion of the transformed phenotype which was associated with the reappearance of extensive microfilament bundles together with vinculin-containing plaques. Both interferon-treated and untreated transformed cells displayed a similar distribution of mitochondria, intermediate filaments, microtubules, and fibronectin. Significant qualitative and quantitative differences between the two types of cells were found in the proteins associated with the cytoskeletal framework by two-dimensional gel analysis.

Relationship of multidrug resistance to rhodamine-123 selectivity between carcinoma and normal epithelial cells: taxol and vinblastine modulate drug efflux.

Preferential retention and cytotoxicity of Rhodamine-123 (Rho-123) was originally reported in a number of carcinoma cell types isolated from a variety of tissues as compared to normal epithelial cells from a limited number of other tissues. In the present study, we have examined Rho-123 selectivity in normal and tumor cell lines isolated from the same tissue source, i.e., human breast. We found that: (a) in matched pairs of normal and carcinoma breast cells, Rho-123 displays no preferential retention in either cell type; (b) there is no preferential toxicity in carcinoma as compared to normal breast cells; in fact, one of the carcinoma cell lines (MDA-MB231) shows moderate resistance to this dye; (c) all of the human breast cell lines do not express P-glycoprotein-mediated multidrug resistance; (d) the normal monkey kidney epithelial cell line CV-1, which was originally used as a model to demonstrate the relative resistance of normal epithelial cells to this drug, is found to express high levels of the mdr-1 gene, is resistant to other multidrug-resistant drugs (taxol and vinblastine), and its resistance to Rho-123 as well as decreased Rho-123 retention can be reversed by verapamil; and (e) taxol and vinblastine are found to block increased Rho-123 efflux in CV-1 cells. Thus, overall the data suggest that preferential retention and cytotoxicity of Rho-123 in carcinoma versus normal epithelial cells is related to the differential expression of the mdr-1 gene.

IL2 triggers a tumor progression process in a melanoma cell line MELP derived from a patient whose metastasis increased in size during IL2/INFalpha biotherapy.

Human melanomas may express both in vivo and in vitro functional IL-Rs and may be expected to directly respond to injected IL2. This may generate biological situations which may be favourable for the patient, but also for tumor progression. Here, we analyse the latter hypothesis. MELP is a melanoma cell line derived from a patient whose metastasis increased in size during IL2/IFN alpha biotherapy [correction of biotheraphy]. These cells have been characterized in vitro for their phenotype and for their sensitivity to IL2. In vitro MELP cells express an IL2-R alpha(+) beta(+) gamma(-) phenotype and IL2 treatment induces the acquisition of new functional characteristics represented (i) by the increased surface expression of two markers of metastatic evolution (ICAM-1 and CD44); (ii) by the stable induction of the IL2-R gamma with the appearance of functional IL2-R beta complex, which are also recognized by GM-CSF; (iii) by the inhibition of transcription of a regulatory cytokine such as IL6; (iv) by a differential effect of IL6 on CD44 surface expression in MELP cells treated or not with IL2 (MILG cells); (v) by the acquisition of faster growth rates and appearance of piling up and multilayer cellular organization; (vi) by the development of rapidly growing tumors in nude mice. IL2 induces in MELP cells a tumor progression process that could mimic the metastatic evolution observed in vivo during biotherapy. Therefore, MELP phenotype may help to define a subset of patients in which IL2 therapy may trigger unfavourable evolution.

IL-15 is produced by a subset of human melanomas, and is involved in the regulation of markers of melanoma progression through juxtacrine loops.

IL-15 is a novel cytokine active through the IL-2R/betagamma. Since several human melanoma cell lines display functional IL-2Rs, we studied the IL-15/melanoma cells interactions. Ten out of 17 melanoma cell lines express the IL-15 transcript and four of them express levels of IL-15 mRNA similar to those detected in control activated monocytes. Nine out of ten cell lines also express two transcripts for the IL-15R alpha originated by the alternative splicing of exon'3'. Two melanoma cell lines, MELP and MELREO, derived from patients with rapidly progressive primary melanomas, co-express the two IL-15 transcripts, originated by alternative splicing of exon 'A'. Intracellular IL-15 protein was only detected in these two cells lines and it is mainly retained in the Endoplasmic Reticulum (ER). However, a small amount of IL-15 is also found in the Golgi apparatus and in the early endosomes, suggesting production and intercellular trafficking of endogenous IL-15 protein. Nevertheless, no biologically active IL-15 could be detected in the supernatant of all melanoma cells. The anti IL-15 blocking mAb M111 causes the up regulation of HLA Class I in dense MELP and MELREO cultures. These data suggest that IL-15 is probably active through juxtacrine loops negatively controlling HLA Class I molecules expression. These data offer, for the first time, a likely explanation to the controversial issue of IL-15 secretion and constitute a natural model for understanding IL-15 routing. Moreover, we identify a subset of melanoma cells producing IL-15, possibly involved in tumor escape mechanisms.

Myofibroblast and concurrent ED-B fibronectin phenotype in human stromal cells cultured from non-malignant and malignant breast tissue.

Primary cultures of stromal cells from non-malignant and malignant breast tissues contained myofibroblasts based on immunoreactivity to alpha-smooth muscle (alpha-sm) actin. The proportions of these cells were variable among cultures from non-malignant origin while consistently high in cultures from carcinomas. High expression of ED-B fibronectin and of type V collagen was observed in myofibroblast-containing cultures. While cells from non-malignant tissues grew relatively steadily, the proliferation of carcinoma-derived cells declined during serial subculturing. In both types of cultures, alpha-sm actin and ED-B fibronectin expression decreased with increasing passage numbers. Epidermal growth factor (EGF), fibroblast growth factor b (FGFb), transforming growth factor alpha (TGF alpha) and platelet-derived growth factor (PDGF) showed consistent mitogenic effects. Addition of FGFb prolonged culture growth and allowed alpha-sm actin and ED-B fibronectin expression to persist. These results demonstrate similar phenotypic modulations in stromal cells from non-malignant and malignant breast tissues that may reflect a common stromal response to various tissue injuries, including neoplasia.

Role of interleukin (IL)-2 and IL-15 in the tumour progression of a melanoma cell line MELP, derived from an IL-2 progressor patient.

MELP is an interleukin (IL)-2 receptor (IL-2R; alpha+ beta+ gamma-) melanoma cell line that was derived, before the beginning of the immunotherapy, from a patient whose metastasis increased in size during treatment with IL-2/interferon-alpha. In these cells, continuous culture in the presence IL-2 (1000 UI/ml) causes the selection of a cell sub-line (termed MILG) expressing the gamma-chain which is tumorigenic in nude mice. Here, we further analysed the characteristics of MELP and MILG cells as well as clones selected at limiting dilution in the presence of high concentrations of IL-2 or IL-15, or those selected after transfection for the expression of a human IL-2 transgene (MELP-CL1). MELP cells, but not six other melanomas cell lines, shed two soluble immunosuppressive molecules, CD25 and intercellular adhesion molecule-1, whose levels also strongly increase in vivo during immunotherapy. In vitro MELP cells express transcripts for IL-6, transforming growth factor, basic fibroblast growth factor and vascular-endothelial growth factor. Cloning at limiting dilution was obtained in culture fed with IL-2 or IL-15. All these clones, as MILG cells, express the transcript for the IL-2R gamma chain. This could favour improved interactions with cytokines using this chain. By contrast, MELP-CL1 cells, which secrete low amounts of biologically active IL-2 (200 UI/10(6) cells) exhibit a phenotype and growth characteristics similar to those of the parental MELP cells. Indeed, a crosslinking experiment with 125I-IL-2, has showed that MELP and MELP-CL1 cells display a scant IL-2 binding ability that is strongly increased in MELP cells fed for 1 week with 1000 UI/ml IL-2. These cells, as well as MILG cells express a betagamma-complex which can also bind IL-15. IL-2 induces a rapid tyrosine phoshorylation in MILG cells, which is followed by a prolonged induction of c-fos and c-jun genes. By contrast, in MELP cells IL-2 only causes a delayed induction of c-myc gene. All MELP derivatives, but not MILG cells, express the transcripts for IL-15, which is not secreted but is present as an intracellular protein. All MELP cells express the transcript for the IL-15R alpha chain. MELP-CL1 cells are not tumorigenic in nude mice, whereas MILG cells form rapidly growing tumours in 75% of the mice. Coinjection at the same site of MILG and MELP-CL1 cells causes the rapid regression of MILG tumours in 80% of the mice, whereas their bilateral injection causes the rapid development of MILG tumours in 100% of the nude mice. Finally, treatment in nude mice of MILG cells with low amounts of IL-2 (1000 UI per mouse) and IL-15 (50 ng per mouse) induces the development of much more aggressive tumours.The expression of functional IL-2Rs in a subset of human melanomas could be responsible for tumour progression.

Differential influence of stromal fibroblasts from different breast tissues on human breast tumour cell growth in nude mice.

The influence of human stromal fibroblasts cultured from normal, non-malignant and malignant breast tissues on in vivo growth of human breast tumour cells was studied. Earlier appearance and increased incidence were observed when low cell inocula of breast MDA-MB 231 tumour cells were coinjected with fibroblasts from either normal or non-malignant mammary tissue. However, at higher cell inoculations the appearance of MDA-MB tumours was delayed while the incidence was reduced. Coinjected fibroblasts derived from breast tumours did not modify MDA-MB tumour growth. The tumourigenic MCF-7 and non-tumourigenic NPM14-T4/9 breast cell lines were not affected by the presence of normal breast fibroblasts. These results indicate that fibroblasts can influence the behavior of tumour cells in vivo but the effects depend on the type and the proportions of coinoculated cells.

Effects of interferons alpha,beta,gamma alone or in combination on the phenotype of human colon carcinoma cells.

The ability of interferons (IFNs) alpha,beta,gamma, alone or in combination, to induce reversion of the phenotype of cloned human colon carcinoma cells during long-term treatment was studied. The phenotypic characteristics examined were proliferation, cellular aggregation and tumorigenicity. The combination of IFN-beta and IFN-gamma showed more antiproliferative activity than that of IFN-delta and IFN-gamma or of either IFN alone. All IFN treatments induced cellular aggregation which was associated with the appearance of brush border microvilli. Both antiproliferative effects and formation of cellular aggregates persisted only in the presence of prolonged treatment with combinations of IFNs alpha,beta with IFN-gamma. No significant differences in the binding of IFN were found between short-and long-term IFN treated cells. Treatment with IFN-beta appeared most effective in decreasing, but not completely suppressing, tumorigenicity.

Morphology and intermediate filament composition of human mammary epithelial cells treated with stable butyrate derivative.

A new stable butyrate derivative monobut-3 was previously shown to inhibit proliferation and promote differentiation in human mammary established cell lines. The present study on monobut-3's effects on mammary epithelial cells cultured from human non-malignant and malignant breast tissues demonstrated pronounced morphological alterations suggestive of cellular differentiation. In addition, some degree of architectural differentiation was also evident in treated primary cultures. Monobut-3 did not affect the expression of vimentin and cytokeratin 18 when assessed in human breast cell lines expressing one or both types of intermediate filaments. However, it did induce expression of cytokeratin 19, characteristic of fully differentiated mammary cells, in one of the two cell lines devoid of this cytokeratin subtype. Furthermore, the network of intermediate filaments was often more largely extended in cells treated with monobut-3 than in untreated ones. These results indicate that monobut-3 can induce subtle changes in intermediate filaments which may contribute to its ability to promote differentiation in human mammary cells.

Steroid hormone receptors and tumorigenicity of sublines from breast tumor metastatic MDA-MB 231 cell line.

Ten cell sublines the MDA-MB 231 human breast cell line were analyzed for their phenotypic diversity: morphology, karyotype, growth rate, clonogenicity in semisolid medium, tumorigenicity in nude mice, number and affinity of nuclear receptors for oestradiol, progesterone and glucocorticoids. Karyotypic analysis showed different aneuploidies from 50 to 120 chromosomes and variable chromosomal rearrangements in the analyzed subclones. All except two of the ten subclones were tumorigenic when injected subcutaneously or intraperitoneally into nude mice. Although the parental cell line has no receptor, all except two of the tested subclones contained various amounts of high affinity oestradiol and progesterone receptors ranging from 3,000 to 33,000 per cell. Seven subclones contained either high affinity oestradiol or progesterone receptors in nuclei. The diversity found in different subclones derived from one breast carcinoma cell line might represent variabilities acquired and selected continuously in culture.

Retinoic acid or methionine enhance interferon's inhibition of the transformed phenotype with no effect on tumorigenicity.

Retinoic acid (RA) and methionine were studied for their relative effectiveness in enhancing the ability of interferons (IFNs) to reverse the phenotype of murine methylcholanthrene (MCA)-transformed cells and human osteosarcoma (OHA) cells. Treatment with RA (1 microM) and methionine (25mM) alone had minimal or no effect on the proliferation of MCA and OHA cells or on the ability to form tumors in animals. Combination of these two agents with IFNs however, potentiated the inhibitory effects of IFNs on proliferation and colony formation of MCA transformed cells but not on their tumorigenicity. Similarly in human tumor OHA cells, only the combination of IFN and RA was more effective than IFN alone on proliferation and colony formation but not on tumorigenicity. Thus, the enhanced effects of combined treatments on cell proliferation in vitro could be distinguished from the inhibitory effects of IFNs on tumorigenicity in both murine transformed cells and human tumor cells.

Differential effects of butyrate derivatives on human breast cancer cells grown as organotypic nodules in vitro and as xenografts in vivo.

The antiproliferative and cytodifferentiating effects of a new stable butyric derivative, monobut-3, were compared using human MDA-MB-231 breast cancer cells grown in three dimension as either in vitro tumor nodules or in vivo xenograft tumors. In in vitro tumor nodules, monobut-3 exhibited marked growth inhibitory effects consistent with the results obtained in monolayer cell cultures. Some functional cell differentiation was also detected in treated nodules. In in vivo xenografts, monobut-3 significantly decreased MDA-MB-231 tumor take but did not affect the rate of tumor growth. No difference was noted in the histological characteristics of the xenografts between untreated and treated mice. Moreover, once monobut-3 treatment was discontinued, tumor growth rapidly resumed in tumor-free animals. The decreased efficacy of monobut-3 in in vivo MDA-MB-231 xenografts as compared to in vitro tumor nodules indicates that factors related to host environment may still limit the clinical effectiveness of this compound.