Search PubMed⌕ Search

Biomedical subjects

H L Moses

Publications and source records attributed to H L Moses.

At least 91 records · Page 5Linked to original sources
PubMed1990

The cell biology of transforming growth factor beta.

The TGF beta family of polypeptide growth factors regulates a remarkable diversity of cellular functions, many of which are not directly associated with cell growth. The present review has summarized many of the recent studies that have just begun to conceptually integrate this expanding array of TGF beta functions into the context of a three-dimensional, multicellular organ or tissue, be it normal or diseased. This fascinating research strongly implicates TGF beta as a key modulator of a wide variety of important physiologic and pathophysiologic processes.

Animals↗
PubMed1990

Transforming growth factors and the regulation of cell proliferation.

The number of different growth regulatory molecules which have been isolated and characterized is continuing to increase. As more information is obtained, it has become apparent that the cooperative actions of many factors with distinct activities is necessary for appropriate proliferative responses. An interplay of both growth stimulatory and growth inhibitory factors is essential for normal growth. Of crucial importance, therefore, is the appropriate regulation of growth factors. Unregulated expression, synthesis, posttranslational processing or activation of either positive or negative growth signals may contribute to neoplastic transformation (Fig. 3). Altered responses to normally positive or negative signals by transformed cells have been demonstrated by several investigators [64, 79, 84]. While altered growth factor responses in transformed cells are well documented, the mechanisms responsible for the loss of growth control are poorly understood and are likely to be both complex and numerous. Continued efforts to dissect and comprehend fully growth factor action on normal cells will be necessary before an understanding of neoplastic transformation can be achieved.

Animals↗
PubMed1990

Isolation and characterization of Kirsten murine sarcoma virus-transformed mouse keratinocytes resistant to transforming growth factor beta.

BALB/MK (MK) is a continuous murine keratinocyte line whose cells are strictly dependent on exogenous epidermal growth factor (EGF) for growth in culture. A derivative cell, KC, resulted from Kirsten murine sarcoma virus transformation, and these cells no longer require EGF for their growth. Despite differences in MK and KC growth conditions, both cell lines are growth inhibited by picomolar concentrations of transforming growth factor-beta (TGF-beta). When MK and KC cells were maintained in the presence of TGF-beta, resistant variants eventually proliferated only from the KC population. In an attempt to determine the mechanism of development of TGF-beta resistance, the TGF-beta-resistant cells (KCR cells) were compared with TGF-beta-sensitive KC cells with regard to growth properties, TGF-beta 1 binding characteristics, and gene expression. KCR cells continued to synthesize DNA and proliferated in the presence of TGF-beta 1 concentrations up to 2 nM, which was 500-fold greater than the ED50 for the sensitive cells. Although the KCR cells possess similar receptor numbers and affinity for TGF-beta 1, we observed differences in affinity cross-linking studies. The KCR cells expressed more of the type III, high molecular weight cell surface binding protein and less of the type II than the KC cells. The type I moiety was clearly altered to a smaller size in some, but not all, KCR cells. In gene regulation studies, there was no apparent difference in c-Ki-ras and v-Ki-ras mRNA levels in the KC and KCR cells. Additionally, expression of TGF-alpha and TGF-beta 1 mRNA was similar in MK, KC, and KCR cells. The expression of proliferation-associated genes, such as c-myc and MGSA/c-gro/kc, which were markedly decreased by TGF-beta 1 in the MK and KC cells, was not altered by TGF-beta 1 in the KCR cells. The data suggest that the loss of TGF-beta 1 responsiveness in the KCR cells was due to an alteration in the TGF-beta receptor that did not permit signal transduction, although the existence of postreceptor alterations cannot be excluded.

Animals↗
PubMed1990

Differential expression of genes encoding TGFs beta 1, beta 2, and beta 3 during murine palate formation.

Transforming growth factor beta 1 (TGF beta 1) has been shown to have multiple effects on primary cultures of palate-derived cell types. We report the analysis, by in situ hybridization, of RNA expression for three different TGF beta isoforms (TGF beta 1, beta 2, and beta 3) during murine embryonic palate development. Differential expression of the three TGF beta genes is seen in the palatal shelves in mesenchymal and epithelial cells known to be involved in the morphogenesis of this organ. Taken together, these results suggest that the TGF beta s act as endogenous factors involved in the formation of the mammalian palate.

Animals↗
PubMed1990

Transforming growth factor beta 1 suppression of c-myc gene transcription: role in inhibition of keratinocyte proliferation.

Transforming growth factor beta 1 (TGF-beta 1) is a potent growth inhibitor for many cell types, including most epithelial cells. However, the mechanism of growth inhibition is unknown. In skin keratinocytes, TGF-beta 1 has been shown to inhibit growth and to rapidly reduce c-myc expression. It has been demonstrated that protein synthesis is required for TGF-beta 1 regulation of c-myc in keratinocytes. Here we present evidence that treatment of mouse BALB/MK keratinocyte cells with either antisense c-myc oligonucleotides or TGF-beta 1 inhibited cell entry into S phase. These results suggest that TGF-beta inhibition of c-myc expression may be essential for growth inhibition by TGF-beta 1. The block in c-myc expression by TGF-beta 1 occurred at the level of transcriptional initiation. Studies with a series of 5' deletion c-myc/chloramphenicol acetyltransferase constructs indicated that a cis regulatory element(s), which resides between positions -100 and +71 relative to P1 transcription start site, is responsible for the TGF-beta 1 responsiveness. Based on these data, it is proposed that the mechanism of TGF-beta 1 growth inhibition involves synthesis or modification of a protein that may interact with a specific element(s) in the 5' regulatory region of the c-myc gene, resulting in inhibition of transcriptional initiation.

Animals↗
PubMed1990

A highly immunogenic tumor transfected with a murine transforming growth factor type beta 1 cDNA escapes immune surveillance.

A highly immunogenic C3H-derived UV-induced tumor was cotransfected with a murine transforming growth factor type beta 1 (TGF-beta 1) cDNA and a neomycin-resistance gene. Stable clones were isolated and used in vitro and in vivo to determine the effects of endogenously produced TGF-beta on cytolytic T-lymphocyte (CTL) responses. Tumor cells producing TGF-beta, though retaining expression for class I major histocompatibility complex molecules and the tumor-specific antigen, did not stimulate primary CTL responses in vitro and were not effective in vivo for directly stimulating primary CTL or in priming for CTL responses. Furthermore, TGF-beta-producing tumors grew progressively in transiently immunosuppressed mice without losing the tumor antigen; thus, TGF-beta produced by tumors may promote escape from immune surveillance.

Animals↗
PubMed1990

Mechanism of activation of latent recombinant transforming growth factor beta 1 by plasmin.

Medium conditioned by Chinese hamster ovary (CHO) cells transfected with the simian pre-pro-TGF beta 1 cDNA contains high levels of latent TGF beta 1. The amino-terminal region of the TGF beta 1 precursor is secreted and can be detected in the conditioned medium by immunoblotting using peptide antibodies specific for amino-terminal peptides. Chemical cross-linking of CHO-conditioned medium using bis-(sulfosuccinimidyl)-suberate (BS3) followed by immunoblot analyses indicates that latent recombinant TGF beta 1 contains both the cleaved amino-terminal glycopeptide and mature TGF beta 1 polypeptide in a noncovalent association and that this association confers latency. The data presented here do not support the involvement of a unique TGF beta binding protein(s) in latent recombinant TGF beta 1. Plasmin treatment of CHO-conditioned medium resulted in the appearance of TGF beta competing activity. In addition, immunoblot analysis of plasmin-treated CHO-conditioned medium indicates that the amino-terminal glycopeptide is partially degraded and that mature TGF beta 1 is released. Thus, activation of latent TGF beta 1 may occur by proteolytic nicking within the amino-terminal glycopeptide thereby causing a disruption of tertiary structure and noncovalent bonds, which results in the release of active, mature TGF beta 1. Acid activation of latent TGF beta, in comparison, appears to be due to dissociation of the amino-terminal glycopeptide from the mature polypeptide.

Animals↗
PubMed1990

Transforming growth factor beta 1-induced changes in cell migration, proliferation, and angiogenesis in the chicken chorioallantoic membrane.

Application of TGF beta 1 (10-100 ng) to the chicken chorioallantoic membrane (CAM) for 72 h resulted in a dose-dependent, gross angiogenic response. The vascular effects induced by TGF beta 1 were qualitatively different than those induced by maximal doses of basic FGF (bFGF) (500 ng). While TGF beta 1 induced the formation of large blood vessels by 72 h, bFGF induced primarily small blood vessels. Histologic analysis revealed that TGF beta 1 stimulated pleiotropic cellular responses in the CAM. Increases in fibroblast and epithelial cell density in the area of TGF beta 1 delivery were observed as early as 4 h after TGF beta 1 treatment. By 8 h, these cell types also demonstrated altered morphology and marked inhibition of proliferation as evidenced by 3H-thymidine labeling. Thus, the TGF beta 1-stimulated accumulation of these cell types was the result of cellular chemotaxis from peripheral areas into the area of TGF beta 1 delivery. Microscopic angiogenesis in the form of capillary sprouts and increased endothelial cell density first became evident at 16 h. By 24 h, capillary cords appeared within the mesenchyme of the CAM, extending towards the point of TGF beta 1 delivery. 3H-thymidine labeling revealed that the growth of these capillary cords was due to endothelial cell proliferation. Finally, perivascular mononuclear inflammation did not become evident until 48 h of treatment, and its presence correlated spatially and temporally with the gross and histological remodelling of newly formed capillary cords into larger blood vessels. In summary, these data suggest that, in the chicken CAM, TGF beta 1 initiates a sequence of cellular responses that results in growth inhibition, cellular accumulation through migration, and microvascular angiogenesis.

Allantois↗
PubMed1990

Expression of and response to growth regulatory peptides by two human pancreatic carcinoma cell lines.

Two human pancreatic adenocarcinoma cell lines (PANC 1 and MIA PACA 2) were examined for expression of growth factors that could potentially play a role either in growth regulation of the tumor cells, or in cells that comprise the stromal elements of tumors. Both cell lines expressed transforming growth factor-alpha (TGF alpha), basic fibroblast growth factor (bFGF), c-sis (PDGF B chain), TGF beta 1, and TGF beta 3 mRNA by Northern blot analysis. Only the PANC 1 cells, however, expressed the TGF beta 2 transcript. TGF beta-like competing activity was found in medium conditioned by either cell line, but TGF alpha-like [epidermal growth factor (EGF)-competing] activity was not detected in the medium from either cell line by radioreceptor assay. TGF alpha and EGF caused concentration-dependent stimulation of soft agar colony growth of the MIA PACA 2 cells, while only TGF alpha caused a significant but less dramatic stimulation of soft agar growth of the PANC 1 cells. Insulin stimulated the anchorage-independent growth of MIA PACA 2 but not PANC 1 cells. Likewise, bFGF also caused a concentration-dependent stimulation of MIA PACA 2 but not PANC 1 growth in soft agar, and PDGF had no effect on the growth of either cell line. TGF beta had no inhibitory or stimulatory effect on soft agar colony growth of either the PANC 1 or the MIA PACA 2 cells, although both cell lines exhibited high affinity, saturable TGF beta binding sites, and TGF beta 1 was capable of autoinduction of TGF beta 1 mRNA expression in PANC 1 cells. The ability to continue to respond to positive growth regulatory factors coupled with the loss of responsiveness to negative growth factors may be important in the pathogenicity of these aggressive tumors.

Adenocarcinoma↗
PubMed1990

Transforming growth factor-beta. A family of growth regulatory peptides.

TGF beta, initially described as a factor that stimulates rodent fibroblast cell lines to proliferate in soft agar, has been shown to be active in several biological processes. The in vitro biological activities of the closely related molecules, TGF beta 1, TGF beta 2, and TGF beta 3, are comparable. Northern blot analyses of adult and embryonic tissues have shown the TGF beta mRNAs to be expressed in vivo, yet their patterns of expression appear somewhat different. In addition, even when all the TGF beta s are expressed in a tissue at the same time, the expression observed has been shown to be localized to different cells within the organ in some cases. This suggests that perhaps these molecules may have activities or functions in mice that are not apparent in vitro. Several members of the TGF beta family of genes have been mapped to mouse chromosome locations near loci previously assigned morphogenetic mutant loci. Although the relationship between the TGF beta genes and these loci have not been proven to be allelic, they may reveal important clues to the true activities of these molecules in vivo.

Animals↗
PubMed1990

The beta-type transforming growth factor. Mediators of cell regulation in the lung.

An increased interest in the role of growth factors in the regulation of processes concerning normal and pathologic lung physiology has spurred a flurry of research in this area. Peptide growth factors are known to control not only cell proliferation but other events such as differentiation, chemotaxis, and matrix deposition as well. The transforming growth factor beta (TGF beta) family of regulatory peptides serves as a prime example to illustrate the multiplicity of effects elicited by peptide growth factors in various lung-derived cell types. At present, the TGF beta family consists of at least 17 proteins and, based on sequence analysis, they can be divided into two groups: a cluster that shows very high sequence similarity to TGF beta 1, the closely related group, and a cluster that shows weaker sequence similarity to TGF beta 1, the distantly related group. The purpose of this brief review is to summarize the salient features of TGF beta structure and regulatory abilities of the closely related group. In addition, we will outline the evidence suggesting a role for TGF beta in normal lung development and physiology. Emphasis will be placed on studies with the closely related members TGF beta 1 and TGF beta 2 because, until recently, purified protein was available only for these two proteins.

Animals↗
PubMed1990

Transforming growth factor-beta activity in sheep lung lymph during the development of pulmonary hypertension.

Chronic pulmonary hypertension is associated with extensive structural remodeling of the pulmonary arterial bed. The structural changes in the arterial walls include increased production of extracellular matrix components and smooth muscle cell hypertrophy, changes that have been similarly induced by transforming growth factor-beta (TGF-beta) in culture. In the present study, experiments were performed to determine whether TGF-beta is present in sheep lung lymph, and whether TGF-beta levels were altered in an animal model of chronic pulmonary hypertension induced by continuous air embolization. Several standard biological assays for TGF-beta activity were used for these determinations including soft agar assays, inhibition of epithelial cell proliferation, and a TGF-beta-specific radioreceptor assay. In each case, control lung lymph contained high concentrations of TGF-beta (100 ng/ml) which required transient acidification for detection. Samples of lung lymph from hypertensive sheep showed a transient and early two- to threefold increase in concentrations of latent TGF-beta. This activity could be partially blocked by TGF-beta antibodies. These studies indicate that sheep lung lymph contains TGF-beta and that the level of TGF-beta increases early during the development of pulmonary hypertension. Thus, TGF-beta may contribute to the development of the structural changes in the pulmonary arteries that occur during the onset of chronic pulmonary hypertension.

Animals↗
PubMed1990

In situ hybridization analysis of TGF beta 3 RNA expression during mouse development: comparative studies with TGF beta 1 and beta 2.

To date, three closely-related TGF beta genes have been found in the mouse; TGF beta 1, TGF beta 2 and TGF beta 3. Previous experiments have indicated that TGF beta 1 and TGF beta 2 may play important roles during mouse embryogenesis. The present study now reports the distribution of transcripts of TGF beta 3 in comparison to the other two genes and reveals overlapping but distinct patterns of RNA expression. TGF beta 3 RNA is expressed in a diverse array of tissues including perichondrium, bone, intervertebral discs, mesenteries, pleura, heart, lung, palate, and amnion, as well as in central nervous system (CNS) structures such as the meninges, choroid plexus and the olfactory bulbs. Furthermore, in several organ systems, TGF beta 3 transcripts are expressed during periods of active morphogenesis suggesting that the protein may be an important factor for the growth and differentiation of many embryonic tissues.

Animals↗
PubMed1990

Altered regulation of protein disulfide isomerase in cells resistant to the growth-inhibitory effects of transforming growth factor beta 1.

A murine keratinocyte cell line that is resistant to the growth-inhibitory effects of transforming growth factor beta 1 (TGF beta 1) was examined for differential gene expression patterns that may be related to the mechanism of the loss of TGF beta 1 responsiveness. Cells that were resistant to the growth-inhibitory effects of TGF beta 1 (KCR cells) were derived from K-ras-transformed BALB/MK keratinocytes (KC cells). Using a subtractive hybridization procedure with KC and KCR mRNAs, we isolated a complementary DNA clone for murine protein disulfide isomerase (PDI). The mRNA for PDI is inhibited by TGF beta 1 treatment in the parental KC cells, but not in the TGF beta 1-resistant KCR cells. Similar PDI down-regulation also occurs in other TGF beta-sensitive cells, but not in a human pancreatic carcinoma cell line which is insensitive to the growth-inhibitory effects of TGF beta 1. The results suggest that misregulation of PDI, an important component of co- and posttranslational modification systems, may be involved in the mechanism by which some cells escape from the growth-inhibitory effects of TGF beta 1.

Animals↗
PubMed1990

Growth stimulation of human breast cancer cells with anti-transforming growth factor beta antibodies: evidence for negative autocrine regulation by transforming growth factor beta.

Exogenous TGF beta inhibits the proliferation of human breast cancer cells in vitro. These cells synthesize and secrete TGF beta into their medium predominantly in a latent form. With neutralizing antibodies against native, biologically active TGF beta (278ab and 282ab), we have examined whether HS578T and MDA-231 breast cancer cells utilize their endogenous TGF beta for growth regulation. Low levels of TGF beta activity were detectable in conditioned medium from confluent monolayers of both cell lines in the absence of acid or protease treatment as measured by radioreceptor assay. When added to subconfluent monolayers of the respective cell line, this untreated conditioned medium inhibited DNA synthesis and cell proliferation. This inhibition was blocked by anti-TGF beta antibodies, whereas nonimmune rabbit IgG had no effect. Similar to exogenous TGF beta 1, this conditioned medium induced a dose-dependent increase in steady-state TGF beta 1 mRNA levels when added to subconfluent HS578T cells; this increase was blocked by the 278ab. Consistent with the above, preincubation of either cell line with anti-TGF beta antibodies increased subsequent specific binding of 125I-TGF beta to cell surface receptors without changing binding affinity. Addition of 278ab to quiescent HS578T or MDA-231 cells induced a dose-dependent increase in [3H]thymidine incorporation. Both antibodies stimulated cell proliferation in serum-free medium and anchorage-independent growth of both cell lines. Finally, incubation of HS578T cells with 278ab under serum-free conditions decreased the basal level of TGF beta 1 message expression. These data indicate that cultured human breast cancer cells utilize endogenously produced TGF beta as an autocrine negative growth regulator.

Antibodies↗
PubMed1989

Growth stimulation, altered regulation of epidermal growth factor receptors, and autocrine transformation of spontaneously transformed normal rat kidney cells by transforming growth factor beta.

The tumorigenic NRK-PT14 cell line requires exogenous epidermal growth factor (EGF), but has lost the requirement for transforming growth factor beta (TGF-beta) for anchorage-independent growth, compared to normal rat kidney (NRK) cells. Development of an optimized serum-free medium for the growth of these cells revealed that NRK-PT14 cells also exhibit a qualitatively altered sensitivity to exogenous type 1 TGF-beta, compared to NRK cells. EGF-induced serum-free monolayer growth of NRK-PT14 cells was stimulated 2-fold by TGF-beta under conditions where growth of NRK cells was inhibited by 67%. TGF-beta only stimulated the growth of NRK-PT14 cells when EGF was present and when EGF was added before TGF-beta. In addition, the stimulation of EGF-induced NRK-PT14 cell growth by TGF-beta was associated with a specific, reversible loss of the high-affinity subpopulation of EGF receptors from the surface of these cells. Treatment of NRK cells with TGF-beta resulted in an increase in this EGF receptor population. Finally, EGF-induced anchorage-independent growth of NRK-PT14 cells was shown to be dependent on secreted TGF-beta, demonstrating an autocrine role for TGF-beta in the transformed phenotype of these cells. Autocrine transformation of NRK-PT14 cells by TGF-beta may result directly from the acquisition of an altered (positive) sensitivity to this growth factor.

Animals↗
PubMed1989

Regulation of intestinal epithelial cell growth by transforming growth factor type beta.

A nontransformed rat jejunal crypt cell line (IEC-6) expresses transforming growth factor type beta 1 (TGF-beta 1) mRNA, secretes latent 125I-labeled TGF-beta 1 competing activity into culture medium, and binds 125I-labeled TGF-beta 1 to specific, high-affinity (Kd = 3.7 pM) cell surface receptors. IEC-6 cell growth is markedly inhibited by TGF-beta 1 and TGF-beta 2 with half-maximal inhibition occurring between 0.1 and 1.0 ng of TGF-beta 1 per ml. TGF-beta 1-mediated growth inhibition is not associated with the appearance of biochemical markers of enterocyte differentiation such as alkaline phosphatase expression and sucrase activity. TGF-beta 1 (10 ng/ml) increases steady-state levels of its own mRNA expression within 8 hr of treatment of rapidly growing IEC-6 cells. In freshly isolated rat jejunal enterocytes that are sequentially eluted from the crypt villus axis, TGF-beta 1 mRNA expression is most abundant in terminally differentiated villus tip cells and least abundant in the less differentiated, mitotically active crypt cells. We conclude that TGF-beta 1 is an autoregulated growth inhibitor in IEC-6 cells that potentially functions in an autocrine manner. In the rat jejunal epithelium, TGF-beta 1 expression is most prominently localized to the villus tip--i.e., the region of the crypt villus unit that is characterized by the terminally differentiated phenotype. These data suggest that TGF-beta 1 may function in coordination of the rapid cell turnover typical for the intestinal epithelium.

Animals↗