Search Research

Transforming growth factor beta receptor type I (TGF-βRI) kinase inhibitors IOA-359 and IOA-360 stimulate erythropoiesis in MDS.

Overactivation of the Transforming Growth Factor Beta (TGF-β) pathway is implicated in the pathogenesis of cytopenias in Myelodysplastic syndromes (MDS) and Acute Myeloid Leukemia (AML). IOA-359 and IOA-360 are potent small molecule inhibitors of the TGF-beta Receptor type I kinase (TGF-βRI, also referred to as ALK5, activin receptor-like kinase 5) that abrogate SMAD phosphorylation in hematopoietic cell lines. Both inhibitors were able to inhibit TGF-β mediated gene transcription at specific doses. ALK5 inhibitors abrogated the growth inhibitory effects of TGF-β on healthy hematopoietic stem cells and stimulated hematopoietic differentiation in cell lines and MDS/AML specimens. These data demonstrate preclinical efficacy of two novel ALK5 inhibitors, IOA-359 and IOA-360, in stimulating erythroid differentiation in MDS and AML.

Ramachandra N, Vegivinti CTR, Sahu S, Sanawar R, Rivera-Peña B, Aminov S, Fromowitz A, Zhang J, Aodengtuya F, Pradhan K, Zhao R, Schwartz L, Alluri S, Thiruvananthapuram V, Rabinovich E, Ajibade O, Gordon-Mitchell S, Shastri A, Deken M, Yingling JM, Sawyer S, Lahn M, Verma A, Leukemia & lymphoma

May 1, 2025

Effect of transforming growth factor beta (TGF-β) receptor I kinase inhibitor on prostate cancer bone growth.

Transforming growth factor beta 1 (TGF-β1) has been implicated in the pathogenesis of prostate cancer (PCa) bone metastasis. In this study, we tested the antitumor efficacy of a selective TGF-β receptor I kinase inhibitor, LY2109761, in preclinical models. The effect of LY2109761 on the growth of MDA PCa 2b and PC-3 human PCa cells and primary mouse osteoblasts (PMOs) was assessed in vitro by measuring radiolabeled thymidine incorporation into DNA. In vivo, the right femurs of male SCID mice were injected with PCa cells. We monitored the tumor burden in control- and LY2109761-treated mice with MRI analysis and the PCa-induced bone response with X-ray and micro-CT analyses. Histologic changes in bone were studied by performing bone histomorphometric evaluations. PCa cells and PMOs expressed TGF-β receptor I. TGF-β1 induced pathway activation (as assessed by induced expression of p-Smad2) and inhibited cell growth in PC-3 cells and PMOs but not in MDA PCa 2b cells. LY2109761 had no effect on PCa cells but induced PMO proliferation in vitro. As expected, LY2109761 reversed the TGF-β1-induced pathway activation and growth inhibition in PC-3 cells and PMOs. In vivo, LY2109761 treatment for 6weeks resulted in increased volume in normal bone and increased osteoblast and osteoclast parameters. In addition, LY2109761 treatment significantly inhibited the growth of MDA PCa 2b and PC-3 in the bone of SCID mice (p<0.05); moreover, it resulted in significantly less bone loss and change in osteoclast-associated parameters in the PC-3 tumor-bearing bones than in the untreated mice. In summary, we report for the first time that targeting TGF-β receptors with LY2109761 can control PCa bone growth while increasing the mass of normal bone. This increased bone mass in nontumorous bone may be a desirable side effect of LY2109761 treatment for men with osteopenia or osteoporosis secondary to androgen-ablation therapy, reinforcing the benefit of effectively controlling PCa growth in bone. Thus, targeting TGF-β receptor I is a valuable intervention in men with advanced PCa.

Wan X, Li ZG, Yingling JM, Yang J, Starbuck MW, Ravoori MK, Kundra V, Vazquez E, Navone NM, Bone

Mar 1, 2012

Rapid cell culture and pre-clinical screening of a transforming growth factor-beta (TGF-beta) inhibitor for orthopaedics.

BACKGROUND: Transforming growth factor-beta (TGF-beta) and bone morphogenetic proteins (BMPs) utilize parallel and related signaling pathways, however the interaction between these pathways in bone remains unclear. TGF-beta inhibition has been previously reported to promote osteogenic differentiation in vitro, suggesting it may have a capacity to augment orthopaedic repair. We have explored this concept using an approach that represents a template for the testing of agents with prospective orthopaedic applications. METHODS: The effects of BMP-2, TGF-beta1, and the TGF-beta receptor (ALK-4/5/7) inhibitor SB431542 on osteogenic differentiation were tested in the MC3T3-E1 murine pre-osteoblast cell line. Outcome measures included alkaline phosphatase staining, matrix mineralization, osteogenic gene expression (Runx2, Alp, Ocn) and phosphorylation of SMAD transcription factors. Next we examined the effects of SB431542 in two orthopaedic animal models. The first was a marrow ablation model where reaming of the femur leads to new intramedullary bone formation. In a second model, 20 microg rhBMP-2 in a polymer carrier was surgically introduced to the hind limb musculature to produce ectopic bone nodules. RESULTS: BMP-2 and SB431542 increased the expression of osteogenic markers in vitro, while TGF-beta1 decreased their expression. Both BMP-2 and SB431542 were found to stimulate pSMAD1 and we also observed a non-canonical repression of pSMAD2. In contrast, neither in vivo system was able to provide evidence of improved bone formation or repair with SB431542 treatment. In the marrow ablation model, systemic dosing with up to 10 mg/kg/day SB431542 did not significantly increase reaming-induced bone formation compared to vehicle only controls. In the ectopic bone model, local co-administration of 38 microg or 192 microg SB431542 did not increase bone formation. CONCLUSIONS: ALK-4/5/7 inhibitors can promote osteogenic differentiation in vitro, but this may not readily translate to in vivo orthopaedic applications.

Schindeler A, Morse A, Peacock L, Mikulec K, Yu NY, Liu R, Kijumnuayporn S, McDonald MM, Baldock PA, Ruys AJ, Little DG, BMC musculoskeletal disorders

May 28, 2010

Effect of an angiotensin II receptor blocker and two angiotensin converting enzyme inhibitors on transforming growth factor-beta (TGF-beta) and alpha-actomyosin (alpha SMA), important mediators of radiation-induced pneumopathy and lung fibrosis.

Progressive, irreversible fibrosis is one of the most clinically significant consequences of ionizing radiation on normal tissue. When applied to lungs, it leads to a complication described as idiopathic pneumonia syndrome (IPS) and eventually to organ fibrosis. For its high mortality, the condition precludes treatment with high doses of radiation. There is widespread interest to understand the pathogenetic mechanisms of IPS and to find drugs effective in the prevention of its development. This report summarizes our experience with the protective effects of L 158,809, an angiotensin II (ANG II) receptor blocker, and two angiotensin converting enzyme (ACE) inhibitors in the development of IPS and the role of transforming growth factor beta (TGF-beta) and of alpha-actomyosin (alpha SMA) in pathogenesis of radiation induced pulmonary fibrosis in an experimental model of bone marrow transplant (BMT). Male WAG/Riji/MCV rats received total body irradiation and a regimen of cyclophosphamide (CTX) in preparation for bone marrow transplant. While one group of animals remained untreated, the remainders were subdivided into three groups, each of them receiving either the ANG II receptor blocker or one of the two ACE inhibitors (Captopril or Enalapril). Each of the three drugs was administered orally from 11 days before the transplant up to 56 days post transplant. At sacrifice time the irradiated rats receiving only CTX showed a chronic pneumonitis with septal fibrosis and vasculitis affecting, in particular, small caliber pulmonary arteries and arterioles. Their lung content of hydroxyproline was also markedly elevated in association with the lung concentrations of thromboxane (TXA2) and prostaglandin (PGI(2)), (two markers of pulmonary endothelial damage). A significant increase of alpha actomyosin staining was observed in vessels, septa and macrophages of the same animals which also overexpressed TGF-beta. When L 158,809, Captopril and Enalapril were added to the radiation and cytoxan treatment, a significant amelioration of the histological damage as well as the overexpression of alpha SMA was observed. Lung concentrations of hydroxyproline, PGI(2), TXA2 and TGF-beta were also observed in these animals so that the values of these compounds were closer to those measured in untreated control rats than to their irradiated and cytoxan treated counterparts. Angiotensin II plays an important role in the regulation of TGF-beta and alpha SMA, two proteins involved in the pathogenesis of pulmonary fibrosis. The finding that ACE inhibitors or ANG II receptor blockers protect the lungs from radiation induced pneumonitis and fibrosis reaffirms the role that ANG II plays in this inflammatory process and suggests an additional indication of treatment of this condition, thus opening a new potential pharmacologic use of these drugs.

Molteni A, Wolfe LF, Ward WF, Ts'ao CH, Molteni LB, Veno P, Fish BL, Taylor JM, Quintanilla N, Herndon B, Moulder JE, Current pharmaceutical design

Jan 1, 2007

A kunitz-type protease inhibitor bikunin disrupts ligand-induced oligomerization of receptors for transforming growth factor (TGF)-beta and subsequently suppresses TGF-beta signalings.

We previously found that bikunin (bik), a Kunitz-type protease inhibitor, suppresses transforming growth factor-beta1 (TGF-beta1)-stimulated expression of urokinase-type plasminogen activator (uPA) in human ovarian cancer cells that lack endogenous bik. In the present study, we tried to elucidate the mechanism by which bik also inhibits plasminogen activator inhibitor type-1 (PAI-1) and collagen synthesis using human ovarian cancer cells. Here, we show that (a) there was an enhanced production of both uPA and PAI-1 in HRA cells in response to TGF-beta1; (b) the overexpression of bik in the cells or exogenous bik results in the inhibition of TGF-beta1 signaling as measured by phosphorylation of the downstream signaling effector Smad2, nuclear translocation of Smad3, and production of PAI-1 and collagen; (c) bik neither decreased expression of TGF-beta receptors (TbetaRI and TbetaRII) in either cell types nor altered the specific binding of 125I TGF-beta1 to the cells, indicating that the effects of bik in these cells are not mediated by ligand sequestration; (d) TbetaRI and TbetaRII present on the same cells exclusively form aggregates in TGF-beta1-stimulated cells; (e) co-treatment of TGF-beta1-stimulated cells with bik suppresses TGF-beta1-induced complex formation of TbetaRI and TbetaRII; and (f) a chondroitin-4-sulfate side chain-deleted bik (deglycosylated bik) does not inhibit TGF-beta1 signaling or association of type I/type II receptor. We conclude that glycosylated bik attenuates TGF-beta1-elicited signaling cascades in cells possibly by abrogating the coupling between TbetaRI and TbetaRII and that this probably provides the mechanism for the suppression of uPA and PAI-1 expression.

Yagyu T, Kobayashi H, Wakahara K, Matsuzaki H, Kondo T, Kurita N, Sekino H, Inagaki K, Suzuki M, Kanayama N, Terao T, FEBS letters

Oct 22, 2004

A novel E1A-like inhibitor of differentiation (EID) family member, EID-2, suppresses transforming growth factor (TGF)-beta signaling by blocking TGF-beta-induced formation of Smad3-Smad4 complexes.

Smad proteins play key roles in intracellular signaling of the transforming growth factor-beta (TGF-beta) superfamily. E1A, an adenoviral oncoprotein, is known to inhibit TGF-beta-induced transactivation through binding to Smad proteins. Recently, an EID-1 (E1A-like inhibitor of differentiation-1) and EID-2 (EID-1-like inhibitor of differentiation-2) were identified. In this study, we examined the effect of EID-2 on Smad-mediated TGF-beta signaling. Here, we show that EID-2 inhibits TGF-beta/Smad transcriptional responses. EID-2 interacts constitutively with Smad proteins, and most strongly with Smad3. Stable expression of EID-2 in the TGF-beta1-responsive cell line inhibits endogenous Smad3-Smad4 complex formation and TGF-beta1-induced expression of p21 and p15. These results suggest that EID-2 may function as an endogenous suppressor of TGF-beta signaling.

Lee HJ, Lee JK, Miyake S, Kim SJ, The Journal of biological chemistry

Jan 23, 2004

Regulation of plasminogen activator inhibitor (PAI)-1 expression in a human trophoblast cell line by glucocorticoid (GC) and transforming growth factor (TGF)-beta.

Plasminogen activator inhibitor (PAI)-1 plays a key role in the regulation of fibrinolysis and cellular invasion by virtue of suppression of plasminogen activator function. Excessive production of placental PAI-1 has been associated with aberrant periplacental fibrin deposition in pregnancies complicated by pre-eclampsia (PE) and intrauterine growth restriction (IUGR). In the current study we used HTR-8/SVneo cells and primary cultures of cytotrophoblasts as models for study of PAI-1 regulation by transforming growth factor (TGF)-beta, and dexamethasone (DEX), a synthetic glucocorticoid (GC). ELISA and Northern blotting assays revealed that DEX treatment significantly enhanced TGF-beta effects on PAI-1 protein and mRNA expression in HTR-8/SVneo cells and cytotrophoblasts. These effects were GC-specific in that DEX and cortisol, but not estradiol, progesterone or testosterone, augmented PAI-1 levels in TGF-beta-treated cells. Conversely, DEX and TGF-beta treatment suppressed PAI-2 levels in HTR-8/SVneo cells and did not affect PAI-2 levels in cytotrophoblasts. PAI-1 promoter assays revealed that TGF-beta, but not DEX, enhanced PAI-1 expression in HTR-8/SVneo cells through a transcriptional mechanism. These results suggest that GC and TGF-beta may alter fibrinolytic and invasive properties of trophoblasts through their effects on PAI-1 expression.

Ma Y, Ryu JS, Dulay A, Segal M, Guller S, Placenta

Nov 1, 2002

Inhibition of transforming growth factor (TGF)-beta1-induced extracellular matrix with a novel inhibitor of the TGF-beta type I receptor kinase activity: SB-431542.

Transforming growth factor beta1 (TGF-beta1) is a potent fibrotic factor responsible for the synthesis of extracellular matrix. TGF-beta1 acts through the TGF-beta type I and type II receptors to activate intracellular mediators, such as Smad proteins, the p38 mitogen-activated protein kinase (MAPK), and the extracellular signal-regulated kinase pathway. We expressed the kinase domain of the TGF-beta type I receptor [activin receptor-like kinase (ALK)5] and the substrate, Smad3, and determined that SB-431542 is a selective inhibitor of Smad3 phosphorylation with an IC50 of 94 nM. It inhibited TGF-beta1-induced nuclear Smad3 localization. The p38 mitogen-activated protein kinase inhibitors SB-203580 and SB-202190 also inhibit phosphorylation of Smad3 by ALK5 with IC50 values of 6 and 3 microM, respectively. This suggests that these p38 MAPK inhibitors must be used at concentrations of less than 10 microM to selectively address p38 MAPK mechanisms. However, the p38 MAPK inhibitor SB-242235 did not inhibit ALK5. To evaluate the relative contribution of Smad signaling and p38 MAPK signaling in TGF-beta1-induced matrix production, the effect of SB-431542 was compared with that of SB-242235 in renal epithelial carcinoma A498 cells. All compounds inhibited TGF-beta1-induced fibronectin (FN) mRNA, indicating that FN synthesis is mediated in part via the p38 MAPK pathway. In contrast, SB-431542, but not the selective p38 MAPK inhibitor SB-242235, inhibited TGF-beta1-induced collagen Ialpha1 (col Ialpha1). These data indicate that some matrix markers that are stimulated by TGF-beta1 are mediated via the p38 MAPK pathway (i.e., FN), whereas others seem to be activated via ALK5 signaling independent of the p38 MAPK pathway (i.e., col Ialpha1).

Laping NJ, Grygielko E, Mathur A, Butter S, Bomberger J, Tweed C, Martin W, Fornwald J, Lehr R, Harling J, Gaster L, Callahan JF, Olson BA, Molecular pharmacology

Jul 1, 2002

Effects of secretory leucocyte protease inhibitor on the production of the anti-inflammatory cytokines, IL-10 and transforming growth factor-beta (TGF-beta), by lipopolysaccharide-stimulated macrophages.

We studied the effects of secretory leucocyte protease inhibitor (SLPI) on the production of the anti-inflammatory cytokines, IL-10 and TGF-beta, by lipopolysaccharide (LPS)-stimulated macrophages, using half-sized SLPI (1/2 SLPI) containing the C-terminal domain (Arg58-Ala107). ELISA testing of macrophage culture fluids showed a temporary production of IL-10 by the macrophages in the early phase (24 h) after LPS stimulation at low (1 ng/ml) or high (10 microg/ml) concentrations. On the other hand, TGF-beta production was initiated after day 3 and progressively increased. 1/2 SLPI significantly increased IL-10 and TGF-beta production by macrophages in response to a low dose as well as a high dose of LPS. Reverse transcription-polymerase chain reaction analysis showed that 1/2 SLPI caused a significant increase in the expression of both IL-10 and TGF-beta mRNAs by LPS-stimulated macrophages. Thus, although the profile of macrophage TGF-beta production by LPS-stimulated macrophages is markedly different from that of their IL-10 production, SLPI causes an up-regulation of the production of these anti-inflammatory cytokines by LPS-stimulated macrophages.

Sano C, Shimizu T, Sato K, Kawauchi H, Tomioka H, Clinical and experimental immunology

Jul 1, 2000

Smad4/DPC4 and Smad3 mediate transforming growth factor-beta (TGF-beta) signaling through direct binding to a novel TGF-beta-responsive element in the human plasminogen activator inhibitor-1 promoter.

The transforming growth factor-beta (TGF-beta) family of cytokines mediates multiple biological effects by regulating the expression of target genes. The Smad family proteins function as intracellular signal transducers downstream of the receptors to transmit the TGF-beta signal from cell membrane to nucleus. The mechanisms by which Smads mediate transcriptional activation of target genes is largely unknown. Here we report the identification of a novel TGF-beta-responsive element in the human type 1 plasminogen activator inhibitor promoter that is required for mediating strong transcriptional activation of this gene by TGF-beta. Smad3 and Smad4 are incorporated into a TGF-beta-inducible complex formed on this element following TGF-beta stimulation of human hepatoma cells. Both Smad3 and Smad4 bind directly to this TGF-beta-responsive element through their conserved MH1 domains. These results indicate that Smad3 and Smad4 mediate TGF-beta signaling by directly interacting with a specific response element in a physiological target gene.

Song CZ, Siok TE, Gelehrter TD, The Journal of biological chemistry

Nov 6, 1998

Inhibitors of dipeptidyl peptidase IV (DP IV, CD26) induces secretion of transforming growth factor-beta 1 (TGF-beta 1) in stimulated mouse splenocytes and thymocytes.

Various studies have shown that the ectoenzyme dipeptidyl peptidase IV (DP IV, CD26), expressed on T, NK and B cells in the human immune system, is involved in the regulation of DNA synthesis and cytokine production. The DP IV/CD26 was found also on mouse splenocytes and thymocytes. Here, we show that the specific DP IV inhibitors Lys[Z(NO2)]-thiazolidide, Lys[Z(NO2)]-pyrrolidide inhibit DNA synthesis as well as production of IL-2, IL-6 and IL-10 of PHA-stimulated mouse splenocytes and Con A-stimulated mouse thymocytes. Most importantly, these inhibitors induce a three to fourfold increased secretion of latent transforming growth factor beta 1 (TGF-beta 1) by mitogen-stimulated mouse immune cells, as measured with a specific TGF-beta 1 enzyme-linked immunosorbent assay (ELISA). These data demonstrate that CD26 plays a role also in regulation of DNA synthesis and cytokine production by murine immune cells, that the enzymatic activity is required for mediating these effects, and that TGF-beta 1 might have key functions in these processes.

Reinhold D, Bank U, Bühling F, Täger M, Born I, Faust J, Neubert K, Ansorge S, Immunology letters

Jun 1, 1997

Transforming growth factor beta (TGF-beta), a potent inhibitor of erythropoiesis: neutralizing TGF-beta antibodies show erythropoietin as a potent stimulator of murine burst-forming unit erythroid colony formation in the absence of a burst-promoting activity.

Transforming growth factor beta (TGF-beta) is a bifunctional regulator of the growth of myeloid progenitors and is here demonstrated to directly inhibit the growth of primitive erythroid progenitors by 95% to 100% regardless of the cytokines stimulating growth. Autocrine TGF-beta production of primitive hematopoietic progenitors has previously been reported. In the present study, a neutralizing TGF-beta antibody (anti-TGF-beta) added to serum-containing cultures, resulted in a 3-, 4-, and 25-fold increase in burst-forming unit erythroid (BFU-E) colony formation in response to interleukin-4 (IL-4) plus erythropoietin (Epo), SCF plus Epo, and IL-11 plus Epo, respectively. The growth of BFU-E progenitors has been suggested to require a burst-promoting activity in addition to Epo. Accordingly, we observed no BFU-E colony formation in serum-containing cultures in response to Epo alone. In contrast, 50 BFU-E colonies were formed when anti-TGF-beta was included in the culture. In serum-free cultures, Epo also stimulated BFU-E colony formation in the absence of other cytokines, whereas anti-TGF-beta had no effect on the number of colonies formed. Quantitation of TGF-beta 1 in serum by an enzyme-linked immunosorbent assay method showed predominantly the presence of precursor (latent) TGF-beta 1, but also showed active TGF-beta 1 at a concentration sufficient to potently inhibit erythroid colony formation. Thus, neutralization of active TGF-beta 1 in serum shows that Epo alone is sufficient to stimulate the growth of murine BFU-E progenitors.

Dybedal I, Jacobsen SE, Blood

Aug 1, 1995

Thrombospondin (TSP) and transforming growth factor beta 1 (TGF-beta) promote human A549 lung carcinoma cell plasminogen activator inhibitor type 1 (PAI-1) production and stimulate tumor cell attachment in vitro.

A growing body of evidence has recently implicated TSP and TGF-beta in the process of malignancy, such as tumor cell proliferation, tumor angiogenesis, and metastasis. The purpose of the present study was to evaluate potential mechanisms of TSP and TGF-beta in tumor cell attachment and invasion. Our results indicate that both TSP and TGF-beta promoted tumor cell attachment and spreading in the presence of plasminogen. The mechanism for these effects appeared to be due, in part, to the capacity of TSP and TGF-beta to induce tumor cell production of (PAI-1). PAI-1, which is a natural inhibitor of tumor-cell associated urokinase-type plasminogen activator (uPA) activity, inhibited activation of plasminogen to plasmin in the growth media, thereby preventing plasmin-induced detachment of cells. The TSP-promoted production of PAI-1 could be inhibited not only by anti-TSP antibodies but also by a neutralizing antibody against TGF-beta. These results suggest that TSP by a mechanism involving TGF-beta can promote cell adhesion through stimulation of tumor cell secretion of PAI-1. These data provide evidence that TSP not only has the capacity of functioning as a matrix protein to directly promote cell-substratum adhesion but that TSP can also stimulate cell adhesion and spreading by modulating cell surface protease expression through stimulation of tumor-associated production of PAI-1.

Albo D, Arnoletti JP, Castiglioni A, Granick MS, Solomon MP, Rothman VL, Tuszynski GP, Biochemical and biophysical research communications

Sep 15, 1994

Human platelet alpha granules contain a nonspecific inhibitor of megakaryocyte colony formation: its relationship to type beta transforming growth factor (TGF-beta).

Whole blood serum (WBS) and platelet-poor plasma-derived serum (PDS) from the same normal subject were compared for their abilities to support human megakaryocyte (MK) colony formation. In all cases, PDS promoted the growth of a higher number (20-50%) of MK colonies than did WBS. Increasing amounts of WBS decreased the number of colonies, whereas increasing concentration of PDS had no marked effects. Crude platelet extracts or platelet secretory products from thrombin-activated platelets also elicited an inhibition of MK colony formation in a dose-dependent manner. A complete inhibition was found for a dose equivalent to 1.10(9) platelets/ml and a 50% inhibition in a range of 1.10(7)-1.10(8) platelets/ml. These platelet products were also inhibitory for erythroid progenitor growth. Platelets from two patients with gray platelet syndrome elicited only a minor inhibition of MK growth, suggesting that the platelet alpha granule is the origin of this inhibition. When platelet extracts were acid-treated, the biological activity of the inhibitor on CFU-MK and CFU-E growth was 20-50-fold higher. In addition, a potent stimulatory activity on the growth of day 7 CFU-GM was observed. The enhancement of biological activities by acid treatment suggests that type beta transforming growth factor (TGF-beta) could be involved in this platelet inhibitory activity. The homogeneous native TGF-beta (from 1 pg to 1 ng/ml) produced the same effects previously induced by platelet products. It totally inhibited CFU-MK growth (at a 500 pg/ml), it inhibited CFU-E growth, and it stimulated growth of day 7 CFU-GM in the presence of a colony-stimulating factor. The inhibition of CFU-MK growth was also observed on purified progenitors. In conclusion, these results suggest that TGF-beta may be implicated in negative autocrine regulation of megakaryopoiesis. However, since this molecule has ubiquitous biological activities, its physiologic relevance as a normal regulator of megakaryopoiesis requires further investigation.

Mitjavila MT, Vinci G, Villeval JL, Kieffer N, Henri A, Testa U, Breton-Gorius J, Vainchenker W, Journal of cellular physiology

Jan 1, 1988

Purification and properties of epithelial growth inhibitor (EGI) from human platelets: its separation from type beta transforming growth factor (TGF-beta).

We previously reported that sera from various kinds of animals contain a protein(s) capable of inhibiting the growth of the non-malignant epithelial cell line derived from Buffalo rat liver (BRL). In the present study, a similar epithelial cell-specific growth inhibitor (EGI) was purified to homogeneity from an acid-ethanol extract of human platelets. During purification, EGI was separated from the major component of type beta transforming growth factor (TGF-beta), which can stimulate the colony formation of the non-malignant fibroblastic cell line derived from rat kidney (NRK) in soft agar in the presence of epidermal growth factor (EGF). The purified EGI had an Mr of 27,000, and was composed of two subunits identical in Mr. It significantly inhibited the growth in monolayer cultures of three non-malignant epithelial cell lines, BRL, MDCK (from Madin-Darby canine kidney) and BSC-1 (from African green monkey kidney), at doses lower than 40 pg/ml in medium containing 10% fetal calf serum. Its inhibitory activity was stable against heating at 90 degrees C for 3 min, but not against treatment with 50 mM dithiothreitol. In addition, TGF-beta was also partially purified from the same extract. The purified TGF-beta did not show any inhibitory activity toward the growth of BRL, MDCK, BSC-1, or NRK.

Huang W, Kimura T, Mashima K, Miyazaki K, Masaki H, Yamashita J, Horio T, Journal of biochemistry

Sep 1, 1986