Biomedical subjects

F W Ruscetti

Publications and source records attributed to F W Ruscetti.

At least 109 records · Page 6Linked to original sources

PubMed1991

Macrophage inflammatory protein (MIP)-1 beta abrogates the capacity of MIP-1 alpha to suppress myeloid progenitor cell growth.

The effects of recombinant murine macrophage inflammatory protein (MIP)-1 beta and MIP-2 on the suppressive activity of MIP-1 alpha were tested using colony formation by human and murine bone marrow burst-forming unit-erythroid (BFU-E), colony-forming unit-granulocyte erythroid macrophage, megakaryocyte (CFU-GEMM), and colony-forming unit-granulocyte macrophage (CFU-GM) progenitor cells. MIP-1 beta, but not MIP-2, when added with MIP-1 alpha to cells, blocked the suppressive effects of MIP-1 alpha on both human and murine BFU-E, CFU-GEMM, and CFU-GM colony formation. Similar results were observed regardless of the early acting cytokines used: human rGM-CSF plus human rIL-3, and two recently described potent cytokines, a genetically engineered human rGM-CSF/IL-3 fusion protein and MGF, a c-kit ligand. The more potent the stimuli, the greater the suppressive activity noted. Pulse treatment of hu bone marrow cells with MIP-1 alpha at 4 degrees C for 1 h was as effective in inhibiting colony formation as continuous exposure of cells to MIP-1 alpha, and the pulsing effect with MIP-1 alpha could not be overcome by subsequent exposure of cells to MIP-1 beta. Also, pulse exposure of cells to MIP-1 beta blocked the activity of subsequently added MIP-1 alpha. For specificity, the action of a nonrelated myelosuppressive factor H-ferritin, was compared. MIP-1 alpha and H-ferritin were shown to act on similar target populations of early BFU-E, CFU-GEMM, and CFU-GM. MIP-1 beta did not block the suppressive activity of H-ferritin. Also, hemin and an inactive recombinant human H-ferritin mutein counteracted the suppressive effects of the wildtype H-ferritin molecule, but did not block the suppressive effects of MIP-1 alpha. These results show that MIP-1 beta's ability to block the action of MIP-1 alpha is specific. In addition, the results suggest that MIP-1 alpha and MIP-beta can, through rapid action, modulate early myeloid progenitor cell proliferation.

Bone Marrow↗

PubMed1991

Establishment of an IL-2 independent, human T-cell line possessing only the p70 IL-2 receptor.

A continuous cell line was established from the blood of a patient (HH) with an aggressive cutaneous T-cell leukemia/lymphoma who lacked antibodies to human T lymphotrophic virus, type I. The immunophenotype of the cultured cells was CD2+, CD3+, CD4+, CD5+, CD8-, DR+ and CD25- (Tac, IL-2 receptor alpha chain). Southern-blot hybridization analysis of T-cell-receptor beta chain DNA demonstrated the same rearrangement in freshly isolated blood cells and cultured cells, indicating that the cell line was derived from the patient's malignant clone. Since cultured T-cells grew in complete medium without added IL-2, we investigated whether HH cells could be producing and responding to IL-2 in an autocrine fashion. However, no IL-2 was detectable in supernatant from the cell line, while antibodies to IL-2, or to the IL-2 receptor alpha or beta chains did not inhibit cell growth. In addition, no mRNA message for IL-2 was detectable in these cells. The results appear to exclude an autocrine IL-2-dependent mechanism of cell growth for this T-cell line. Although cultured HH cells lacked detectable IL-2 receptor alpha chain, they did show increased proliferation to exogenous IL-2. Binding studies with 125I-IL-2 demonstrated an intermediate affinity receptor for IL-2, KD = 1.7 nM, with 6400 binding sites per cell, suggesting the presence of an IL-2 receptor beta chain. Consistent with these findings 125I-IL-2 cross-linking studies demonstrated a single receptor calculated to be 75 kDa. Also, the beta chain of the IL-2 receptor was detected by immunofluorescence using specific monoclonal antibodies (MAbs). Nanomolar concentrations of an IL-2-diphtheria toxin fusion protein inhibited cellular protein synthesis, an effect abrogated by native IL-2. These findings indicate that the IL-2 receptor beta-chain was functional. This novel mature T-cell line may be useful in studies of IL-2 receptor regulation and in analysis of the mechanism of T-cell leukemogenesis.

DNA, Neoplasm↗

PubMed1991

Stimulation of granulopoiesis by transforming growth factor beta: synergy with granulocyte/macrophage-colony-stimulating factor.

Transforming growth factor beta 1 (TGF-beta 1) is known to inhibit the growth of immature hematopoietic progenitor cells, whereas more mature, lineage-restricted progenitors are not inhibited. In contrast, in the presence of saturating concentrations of granulocyte/macrophage-colony-stimulating factor (GM-CSF), TGF-beta promoted a 3- to 5-fold increase in the number and size (greater than 0.5 mm) of bone marrow colonies in a dose-dependent manner with an ED50 of 10-20 pM; TGF-beta 1 alone had no effect. Morphological examination showed an increase in granulocyte colonies. In suspension cultures, TGF-beta 1 and GM-CSF stimulated an increase in total viable cells with markedly enhanced neutrophilic differentiation and a concomitant decrease in the number of monocytes/macrophages by day 6 in culture. Limiting dilution analysis demonstrated a 2- to 5-fold increase in the frequency of progenitor cells that responded to GM-CSF plus TGF-beta 1 vs. GM-CSF alone. Bone marrow progenitors obtained from mice 3 days after treatment with 5-fluorouracil responded to a combination of GM-CSF and TGF-beta 1, whereas either factor alone had no effect. A single-cell assay identified a progenitor cell that directly responded to TGF-beta and GM-CSF. TGF-beta increased the number of GM-CSF receptors on bone marrow cells. Thus, TGF-beta 1 can act as a bifunctional mediator of hematopoietic cell growth, and TGF-beta 1 and GM-CSF act together to stimulate granulopoiesis as measured by large granulocyte colony formation; the progenitor cell is tentatively designated granulocyte burst-forming unit.

Animals↗

PubMed1991

Characterization and regulation of RB6-8C5 antigen expression on murine bone marrow cells.

Murine bone marrow cells expressing the cell surface Ag RB6-8C5 were identified by fluorescence-activated cell-sorting analysis using a rat IgG mAb. The fluorescent intensity of RB6-8C5 was variable on bone marrow cells. This made it possible to separate bone marrow cells into distinct subpopulations, RB6-8C5neg, RB6-8C5lo, and RB6-8C5hi cells. Morphologic analysis of the sorted populations demonstrated that the Ag was expressed on myeloid cells. The expression of RB6-8C5 increases with granulocyte maturation, whereas expression is transient on cells in the monocytic lineage. The RB6-8C5hi sorted cells were enriched for end-stage neutrophils (75%), whereas the RB6-8C5lo sorted cells contained more immature myeloid cells and myelocytes (75%). Lymphocytes and macrophages were less than 5% in any RB6-8C5+ population, whereas the erythroid precursors were RB6-8C5neg. The colony forming unit culture (CFU-C) (greater than 90%) were found in the RB6-8C5neg and RB6-8C5lo populations, and all the CFU-granulocyte, erythroid, megakaryocyte, and macrophage (CFU-GEMM) and burst-forming units-erythroid (BFU-E) were in the RB6-8C5neg population. Granulocyte-macrophage-CSFR (GM-CSFR) and IL-1 alpha R were expressed on RB6-8C5hi bone marrow cells, whereas no receptors could be detected on RB6-8C5neg and RB6-8C5lo cells. The expression of the RB6-8C5 Ag can be induced on RB6-8C5neg cells in liquid culture by IL-3 and granulocyte-macrophage CSF. Thus, RB6-8C5 is a myeloid differentiation Ag whose expression can be regulated by cytokines.

Animals↗

PubMed1991

Mechanistic studies of transforming growth factor-beta inhibition of IL-2-dependent activation of CD3- large granular lymphocyte functions. Regulation of IL-2R beta (p75) signal transduction.

CD3- large granular lymphocyte (LGL) express constitutive levels of functional IL-2R beta. TGF-beta inhibited several IL-2R beta-mediated events in LGL, including IL-2-induced NK and lymphokine-activating factor activities, IFN-gamma gene expression and secretion, and IL-2R alpha expression. TGF-beta inhibited these IL-2-induced LGL functions in a dose-dependent and reversible manner. By contrast, TGF-beta had little effect on LGL IL-2R beta expression and TGF-beta receptors were not induced by IL-2. Studies were performed to examine binding and internalization of radiolabeled IL-2. These experiments demonstrated that the rapid binding and internalization of [125I]IL-2 was not altered in CD3- LGL pretreated with TGF-beta. These internalization studies indicated that the TGF-beta inhibition represented postreceptor-binding events in NK cells. Further studies were initiated to examine signaling events in CD3- LGL. When IL-2-induced tyrosine phosphorylation events were examined, significant inhibition was seen of selected phosphoproteins in TGF-beta-pretreated cells. In addition, the ability of TGF-beta to also inhibit IL-2 induction of LGL IL-2R alpha and IFN-gamma mRNA expression was consistent with the hypothesis that posttranscriptional mechanisms were unlikely to be affected by TGF-beta. Collectively, these data indicated that TGF-beta inhibited IL-2-induced CD3- LGL functions and suggested that TGF-beta inhibition occurs either at the level of specific tyrosine phosphorylation and/or IL-2-induced transcriptional control factors.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1991

Differential expression of transforming growth factor-beta 1 (TGF-beta 1) receptors in murine myeloid cell lines transformed with oncogenes. Correlation with differential growth inhibition by TGF-beta 1.

Transforming growth factor-beta 1 (TGF-beta 1) is a pleiotropic polypeptide hormone known to play an important role as a modulator of hematopoietic processes in human and murine cells. One of the characteristics of TGF-beta 1 is the ability to inhibit the growth of several cell types, including cells of the myeloid lineage. To study the mechanism by which TGF-beta 1 inhibits the growth of myeloid cells, we have used three murine myeloid cell lines, the parental interleukin-3-dependent 32D-123 cell line and two retrovirally infected interleukin-3-independent cell lines (32D-abl, 32D-src), all of which are growth inhibited by TGF-beta 1. Each of these oncogene-transfected cells expresses a greater number of TGF-beta 1 receptors than the parental cell line and responds to TGF-beta 1 with increased sensitivity; 32D and 32D-src cells are 2- and 58-fold more sensitive to TGF-beta 1 inhibition than the parental cell line (ED50 = 35 pM). Both 32D-abl- and 32D-src-transformed cell lines expressed higher levels of the 65- and 85-kDa TGF-beta 1 receptor species than did the parental cells. We observed a correlation between the greater sensitivity of 32D-src cells to TGF-beta 1 and the more rapid down-modulation and reappearance of cell surface TGF-beta 1 receptors on 32D-src cells. Thus, the level of TGF-beta 1 receptor expression and rate of reexpression both have a crucial regulatory effect on the functional activity of the TGF-beta 1 ligand.

Animals↗

PubMed1991

Generation of lymphokine-activated killer activity in T cells. Possible regulatory circuits.

CD4+ and CD8+ T cells do not develop significant lymphokine-activated killer (LAK) activity when PBL are cultured with IL-2 or even when they are activated with a T cell stimulus such as OKT3 mAb. The possibility that a T cell regulatory mechanism prevents the development of LAK activity by CD4+ or CD8+ cells in OKT3 mAb and IL-2 cultures was tested by depleting CD8+ or CD4+ cells from PBL before stimulation with OKT3 and IL-2. Under these conditions, the remaining CD4+ and CD8+ cells were able to generate non-MHC-restricted lysis of NK-resistant tumor targets. Our data suggested that a regulatory signal was present in the culture to prevent the development of lytic function by T cells. T cells removed from the PBL cultures were, upon culture with IL-2, able to generate high LAK activity, suggesting that inhibition of the CD4+ or CD8+ T cell-mediated LAK activity was an active ongoing process, which blocked the lysis at the level of the activated cell and not the precursor cell. Mixing experiments demonstrated that the CD4+ or the CD8+ cells isolated from the PBL cultures were able to inhibit the development of lytic function in the CD4-depleted and CD8-depleted cultures. Transforming growth factor-beta (TGF-beta) has been shown to block LAK activity of NK cells in IL-2-stimulated cultures. When TGF-beta was added to CD4(+)- or CD8(+)-depleted cultures, it also inhibited LAK activity of T cells in a dose-dependent fashion, without interfering with T cell growth. Lytic activity returned to activated levels when TGF-beta was removed from the culture medium, thereby demonstrating the reversibility of TGF-beta inhibition.

Antibodies, Monoclonal↗

PubMed1991

Transforming growth factor-beta trans-modulates the expression of colony stimulating factor receptors on murine hematopoietic progenitor cell lines.

Transforming growth factor beta (TGF-beta) is a potent and selective growth inhibitor of early hematopoietic progenitors and leukemic cells. The cellular mechanism(s) underlying this antiproliferative effect is, however, currently unknown. In the present study, we demonstrate that TGF-beta inhibits the expression of granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin 3 (IL-3), and granulocyte-CSF (G-CSF) receptors on murine factor-dependent and independent hematopoietic progenitor cell lines without a significant change in receptor affinity. A maximum reduction in GM-CSF receptor numbers of 65% to 77% was observed by 96-hour incubation with TGF-beta. The TGF-beta induced trans-down-modulation of GM-CSF receptors was prolonged, noncytotoxic but reversible, and not due to endogenous production of GM-CSF. The TGF-beta induced reduction in CSF receptor numbers preceded TGF-beta's growth inhibitory action. In addition, the ED50 (1 to 10 pmol/L) for TGF-beta's CSF receptor modulatory and antiproliferative effect was similar. The effect of TGF-beta on cell surface CSF receptor expression was specific, because the expression of other cell surface proteins (Ly 5 and Ly 17) was not affected by TGF-beta treatment, and because other growth inhibitors (tumor necrosis factor and interferon) did not affect CSF receptor expression. These data suggest that the downregulation of the growth of hematopoietic progenitor cells by TGF-beta involves reducing the cell surface expression on growth factor receptors.

Animals↗

PubMed1991

Induction of transforming growth factor-beta 1 (TGF-beta 1), receptor expression and TGF-beta 1 protein production in retinoic acid-treated HL-60 cells: possible TGF-beta 1-mediated autocrine inhibition.

Treatment of HL-60 cells, a human promyelocytic leukemia cell line, with the vitamin A derivative retinoic acid (RA) for 7 days resulted in a dose-dependent decrease in proliferation and increase in granulocytic differentiation. The role of transforming growth factor-beta 1 (TGF-beta 1), a protein with pleiotropic effects on the proliferation and differentiation of various cell types, was examined during RA-induced differentiation of HL-60 cells. Although TGF-beta 1 alone had little effect on proliferation or differentiation of HL-60 cells, addition of TGF-beta 1 to HL-60 cells treated with a suboptimum concentration of RA (1.0 nmol/L) resulted in a marked decrease in proliferation with no effect on granulocytic differentiation. Studies of the mechanism of RA-induced TGF-beta sensitivity showed that although untreated HL-60 cells expressed low levels of TGF-beta 1 binding proteins on the cell surface, the levels were increased in a dose-dependent manner after RA treatment. Maximum induction was achieved after treatment with 10 nmol/L RA and consisted predominantly of the 65-Kd TGF-beta 1 receptor type. Moreover, RA treatment also resulted in a dose-dependent increase in both TGF-beta 1 steady-state mRNA expression and production of active TGF-beta with maximum induction at 10 nmol/LRA. RA treatment of HL-60 cells had no effect on TGF-beta 2 and TGF-beta 3 mRNA expression. These data suggest that the effects of RA may be mediated by a TGF-beta 1-mediated autocrine antiproliferative loop during differentiation of HL-60 cells.

Cell Differentiation↗

PubMed1991

Synergistic inhibition of phorbol ester-induced transformation of JB6 cells by transforming growth factor-beta and retinoic acid.

Transforming growth factor-beta (TGF-beta) plays a complex role as a regulator of proliferation and differentiation of many cell types, including cells of epithelial origin. In this study, we examined whether TGF-beta, alone or in combination with retinoic acid, was able to inhibit the transformation of the murine epidermal cell line JB6. When treated with phorbol myristate acetate (PMA) and other tumor promoters, the nontumorigenic and anchorage-dependent JB6 cells acquired a tumor phenotype, as shown by the acquisition of tumorigenicity and anchorage independence. We found that TGB-beta inhibited the PMA-induced transformation of a subclone of JB6 cells. The effect of TGF-beta was due to an anti-transformation promoting activity, rather than to generalized growth inhibition, since TGF-beta neither inhibited the growth of monolayer cultures of JB6 cells, nor affected the colony-forming efficiency in agar of the JB6-derived permanently transformed RT101 cell line. TGF-beta was synergistic with retinoic acid, a known anti-tumor promoter, in inhibiting the PMA-induced transformation of JB6 cells. Examination of TGF-beta receptor expression on JB6 cells, by both binding and affinity labeling, showed that treatment with PMA significantly decreased TGF-beta receptor expression while retinoic acid counteracted this effect of PMA, thus suggesting that the synergy between retinoic acid and TGF-beta may be due, at least in part, to modulation of TGF-beta receptor expression. TGF-beta, therefore, appears to function as an incomplete antipromoter whose action can be permitted and/or complemented by retinoic acid. Our data demonstrating that TGF-beta has anti-transformation promoting activity suggest that TGF-beta plays a role in maintaining homeostasis of epithelial cells, not only by regulating cell proliferation and differentiation, but also by counteracting events that lead to malignant transformation.

Animals↗

PubMed1991

In vivo and in vitro effects of TGF-beta 1 on normal and neoplastic haemopoiesis.

TGF-beta 1 and TGF-beta 2 are equipotent selective inhibitors of murine and human haemopoiesis in vitro. Primitive haemopoietic cells such as the high proliferative potential progenitor cell and the colony-forming unit (CFU)-GEMM are directly inhibited by TGF-beta whereas the more differentiated CFU-G, CFU-M and CFU-E are not. Recombinant TGF-beta 1 administered intraperitoneally or intravenously to mice selectively inhibits haemopoietic colony formation in a time- and dose-dependent manner to the same extent as seen in vitro. The progenitors are reversibly prevented from entering the cell cycle. This inhibitory action of TGF-beta functions on at least two levels: (1) down-modulation of the cell surface expression of receptors for growth stimulatory molecules and (2) interference with the intracellular signalling pathways of these molecules. In addition, expression of TGF-beta receptors is regulated during cytokine stimulation of haemopoiesis. Neoplastic B lymphocytes can proliferate by escaping from a TGF-beta-mediated autocrine inhibitory loop. Activation signals (e.g. phorbol esters) inhibit tumour cell growth by stimulating active TGF-beta production and inducing cell surface expression of TGF-beta receptors. These results indicate that TGF-beta may be useful as a bone marrow protective and/or an antitumour agent.

Animals↗

PubMed1991

Transient reversal of bone marrow aplasia associated with lymphocyte depleted Hodgkin's disease after combination chemotherapy.

This report describes a patient with lymphocyte depleted Hodgkin's disease who presented with bone marrow aplasia. The aplastic marrow reverted to normal after initiation of MOPP chemotherapy; however, 4 months after completion of therapy, bone marrow aplasia recurred in the absence of recurrent Hodgkin's disease. The patient remains free of Hodgkin's disease 34 months after completion of chemotherapy. Bone marrow abnormalities in Hodgkin's disease are reviewed and the current understanding of the pathological mechanisms leading to aplastic anemia is discussed.

Adult↗

PubMed1991

Transforming growth factor-beta and the immune system.

It is now apparent that the transforming growth factor beta (TGF-beta) family of proteins has potent immunoregulatory properties ranging from effects on the growth and differentiation of primitive stem cells to the differentiated functions of immune effector cells. Although most reports have described the immunosuppressive activities of TGF-beta, recent evidence supports the concept that TGF-beta can have both inhibitory and stimulatory actions on these systems. Recently, it has been found that TGF-beta can have autocrine as well as paracrine effects on the immune system, indicating that immune cells can activate the inactive secreted form of TGF-beta. Furthermore, TGF-beta has differential intracellular effects on cell surface receptor modulation, tyrosine phosphorylation, and cytokine gene transcription as well as cell-mediated cytotoxicity. Importantly, the administration of TGF-beta has proven beneficial in several animal disease models such as septic shock, allograft rejection, and autoimmunity. Moreover, the increased levels of TGF-beta found in several disease states associated with immunosuppression such as different forms of malignancy, chronic degenerative diseases, and AIDS implicate the involvement of TGF-beta in the pathogenesis of some diseases. Ultimately, well designed clinical trials will determine whether the exciting potential of TGF-beta can be used to treat or prevent disease.

Animals↗

PubMed1991

Role of transforming growth factor-beta 1 in regulation of hematopoiesis.

The data presented above suggest that one possible clinical use of TGF-beta would be to protect the bone marrow from the effects of myelosuppressive chemotherapeutic drugs by preventing entry or removing primitive stem cells from the cell cycle. It may also have the additional benefit of reducing the drug-induced neutrophil nadir by stimulating granulopoiesis. The availability of large quantities of recombinant TGF-beta will allow study of the pharmacokinetics with different routes of administration, dosage effects, and details of the pleiotropic effects on other cell systems. Experiments are in progress to determine whether TGF-beta will allow the delivery of higher amounts or more frequent doses of chemotherapeutic drugs and thus allow increased antitumor efficacy in tumor-bearing animals.

Animals↗

PubMed1990

IL-1 alpha induces expression of active transforming growth factor-beta in nonproliferating T cells via a post-transcriptional mechanism.

IL-1 is a co-stimulus for T cell proliferation along with TCR cross-linking agents or lectins. Here we demonstrate that IL-1 alpha, in the absence of a TCR stimulus, induces active TGF-beta production by non-proliferating T cells. Thus, in addition to being an incomplete signal, IL-1 alpha alone induced the production of a negative modulator for T cell proliferation. Interestingly, when Con A and IL-1 were combined, active TGF-beta was not detected in supernatants. Production of active TGF-beta protein by T cells in response to IL-1 alpha was established by 1) growth inhibition of the TGF-beta-responsive CCL 64 target cell, 2) neutralization of the activity in supernatants with an anti-TGF-beta mAb, and 3) competition of supernatants with [125I]TGF-beta binding to CCL 64 membranes. The mechanism of IL-1 alpha induction of TGF-beta was examined: IL-1 alpha did not increase TGF beta-1 message over constitutive levels, nor did it induce transcription of TGF-beta 2 message. A latent acid-activatable form of the protein was detected in nonproliferating murine T cells. We therefore suggest that IL-1 alpha regulates TGF-beta expression in T cells through translational and/or post-translational mechanisms. IL-1 regulation of active TGF-beta production by T cells may be a mechanism for controlling the proliferative response of T cells to a co-stimulus, and may be relevant in the pathophysiology of certain chronic inflammatory disease states.

Animals↗

PubMed1990

Chemoprotective effects of recombinant human IL-1 alpha in cyclophosphamide-treated normal and tumor-bearing mice. Protection from acute toxicity, hematologic effects, development of late mortality, and enhanced therapeutic efficacy.

In this study, recombinant human IL-1 alpha (rhIL-1 alpha) was used to protect normal and tumor-bearing BALB/c mice from the acute toxicity caused by lethal doses of cyclophosphamide (Cy) and 5-fluorouracil. Pretreatment of mice for 7 days with 10,000 U/day of rhIL-1 alpha protected 70 to 100% of mice from the acute death induced by lethal doses of both Cy (380 mg/kg) and 5-fluorouracil (250 mg/kg). In contrast, post-treatment of mice with single or multiple doses of rhIL-1 alpha was not chemoprotective. Pretreatment of mice with rhIL-1 alpha increased the acute LD90 of Cy from 380 mg/kg to greater than 500 mg/kg in normal mice, an LD90 dose-modifying effect of at least 1.25, was accompanied by a more rapid recovery from neutropenia and a less severe reduction in the number of bone marrow single lineage monocyte, myeloid, or myelomonocytic colonies. Some of the mice (10 to 50%) that were successfully protected by pretreatment with rhIL-1 alpha died after day 50. These mice consistently presented with extensive pulmonary inflammation and fibrosis at death. Mice bearing murine renal cancer (Renca) were also protected from the acute toxic effects of Cy (450 mg/kg) by pretreatment with rhIL-1 alpha. Renca-bearing mice pretreated with rhIL-1 alpha and either sublethal (300 mg/kg) or lethal (450 mg/kg) doses of Cy exhibited enhanced survival times over those of untreated Renca-bearing mice. Interestingly, the cause of death in Renca-bearing mice that ultimately failed treatment with rhIL-1 alpha plus 300 mg/kg Cy was recurrent tumor, whereas most mice treated with rhIL-1 alpha plus 450 mg/kg Cy had no detectable tumor, although several died from late pulmonary inflammation and fibrosis. Thus, the dose escalation of Cy in rhIL-1 alpha-pretreated mice results in greater antitumor effects of Cy. However, the dose escalation of some cytotoxic agents allowed by the use of myelostimulatory agents can result in late fatal complications not detected in acute toxicity testing.

Animals↗

PubMed1990

Inhibition of murine monocyte proliferation by a colony-stimulating factor-1 antisense oligodeoxynucleotide. Evidence for autocrine regulation.

Using a combination of v-myc and v-ras oncogenes, we have established a growth factor-independent monocyte cell line from murine fetal liver (FL-ras/myc). Biologic and molecular characterization demonstrated that the gene for the macrophage growth factor CSF-1 and the c-fms proto-oncogene (CSF-1 receptor) are expressed in this cell line, thus suggesting autocrine regulation as a possible mechanism for the unregulated growth of these cells. To study this possibility, we used 1) mAb, to neutralize the CSF-1 protein produced by the cell line, and 2) antisense oligomers, to inhibit CSF-1 gene products by specific base-pairing of complementary nucleic acids. We report here that both approaches inhibited in vitro cell growth by 60 to 70%, whereas the combination of oligomer and mAb inhibited proliferation by 95%. However, control antisense oligomers (50% bp mismatch with CSF-1 mRNA) did not inhibit FL-ras/myc cell growth. Furthermore, the inhibitory effects of mAb and oligomers were reversible when they were removed from the media. Detection of cell-associated CSF-1 protein by immunofluorescence showed that cells treated with the antisense oligomer expressed significantly less CSF-1 protein. These results indicate that the FL-ras/myc cell line requires CSF-1 for autonomous growth and that oligomers can efficiently block production of autocrine growth factors.

Animals↗

PubMed1990

Transforming growth factor beta is a potent inhibitor of interleukin 1 (IL-1) receptor expression: proposed mechanism of inhibition of IL-1 action.

Transforming growth factor beta (TGF-beta) acts as a potent inhibitor of the growth and functions of lymphoid and hemopoietic progenitor cells. Cell proliferation depends not only on the presence of growth factors, but also on the development of specific receptor-signal transducing complexes. We therefore investigated whether the inhibitory actions of TGF-beta could be mediated by inhibition of growth factor receptors. TGF-beta inhibited the constitutive level of interleukin 1 receptor (IL-1R) expression on several murine lymphoid and myeloid progenitor cell lines, as well as IL-1R expression induced by interleukin 3 (IL-3) on normal murine and human bone marrow cells. Furthermore, treatment of bone marrow progenitor cells with TGF-beta concomitantly inhibited the ability of IL-1 to promote high proliferative potential (HPP) colony formation as well as blocked IL-1-induced IL-2 production by EL-4 6.1 cells. These findings provide the first evidence that the inhibitory action of TGF-beta on the growth and functional activities of hematopoietic and T cells is associated with a reduction in the cell surface receptor expression for IL-1.

Animals↗