Regulation of the effects of TGF-beta 1 by activation of latent TGF-beta 1 and differential expression of TGF-beta receptors (T beta R-I and T beta R-II) in idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is characterised by subpleural fibrosis that progresses to involve all areas of the lung. The expression of transforming growth factor-beta1 (TGF-beta 1), a potent regulator of connective tissue synthesis, is increased in lung sections of patients with IPF. TGF-beta 1 is generally released in a biologically latent form (L-TGF-beta 1). Before being biologically active, TGF-beta must be converted to its active form and interact with both TGF-beta receptors type I and II (T beta R-I and T beta R-II). TGF-beta latency binding protein 1 (LTBP-1), which facilitates the release and activation of L-TGF-beta 1, is also important in the biology of TGF-beta 1. METHODS: Open lung biopsy samples from patients with IPF and normal controls were examined to localise T beta R-I, T beta R-II, and LTBP-1. Alveolar macrophages (AM) and bronchoalveolar lavage (BAL) fluid were examined using the CCL-64 bioassay to determine if TGF-beta is present in its active form in the lungs of patients with IPF. RESULTS: Immunoreactive L-TGF-beta 1 was present in all lung cells of patients with IPF except for fibroblasts in the subepithelial regions of honeycomb cysts. LTBP-1 was detected primarily in AM and epithelial cells lining honeycomb cysts in areas of advanced IPF. In normal lungs LTBP-1 immunoreactivity was observed in a few AM. AM from the upper and lower lobes of patients with IPF secreted 1.6 (0.6) fmol and 4.1 (1.9) fmol active TGF-beta, respectively, while AM from the lower lobes of control patients secreted no active TGF-beta (p< or =0.01 for TGF-beta in the conditioned media from AM obtained from the lower lobes of IPF patients v normal controls). The difference in percentage active TGF-beta secreted by AM from the lower lobes of patients with IPF and the lower lobes of control patients was significant (p< or =0.01), but the difference between the total TGF-beta secreted from these lobes was not significant. The difference in active TGF-beta in conditioned media of AM from the upper and lower lobes of patients with IPF was also not statistically significant. BAL fluid from the upper and lower lobes of patients with IPF contained 0.7 (0.2) fmol and 2.9 (1.2) fmol active TGF-beta, respectively (p< or =0.03). The percentage of active TGF-beta in the upper and lower lobes was 17.6 (1.0)% and 78.4 (1.6)%, respectively (p< or =0.03). In contrast, BAL fluid from control patients contained small amounts of L-TGF-beta. Using immunostaining, both T beta R-I and T beta R-II were present on all cells of normal lungs but T beta R-I was markedly reduced in most cells in areas of honeycomb cysts except for interstitial myofibroblasts in lungs of patients with IPF. TGF-beta 1 inhibits epithelial cell proliferation and a lack of T beta R-I expression by epithelial cells lining honeycomb cysts would facilitate repair of the alveoli by epithelial cell proliferation. However, the presence of both T beta Rs on fibroblasts is likely to result in a response to TGF-beta 1 for synthesis of connective tissue proteins. Our findings show that biologically active TGF-beta 1 is only present in the lungs of patients with IPF. In addition, the effects of TGF-beta 1 on cells may be further regulated by the expression of T beta Rs. CONCLUSION: Activation of L-TGF-beta 1 and the differential expression of T beta Rs may be important in the pathogenesis of remodelling and fibrosis in IPF.

Quantitative assessment of cranial defect healing and correlation with the expression of TGF-beta.

Circular parietal defects from 3 to 12 mm in diameter were made in 45 6-month old skeletally mature guinea pigs, and animals were sacrificed after survival periods of 3 days to 12 weeks. The original defect was harvested in continuity with a rim of surrounding bone and the adjacent dura and pericranium. After 12 weeks, all 3 and 5 mm defects were completely covered by a bridge of bone, while residual defects were noted within the 8 and 12 mm wounds. Percentage of new bone formation was significantly higher within 3 mm defects, than in all larger defects at each time interval from 1 week on (P < .05), reaching a mean of 93% in 3 mm defects and remaining below a mean of 31% in the remaining defect sizes. Immunolocalization demonstrated an osteogenic front in which the osteoblasts stained strongly for all isoforms of TGF-beta, with the intensity decreasing after the majority of the defects had reossified; this front was located at the advancing bone edge of the defect as well as the endocranial side adjacent to the dura. In conclusion, isoforms of TGF-beta are upregulated during a limited "window" of time corresponding to the period of calvarial reossification, and are localized to osteoblasts within an osteogenic front at the periphery and dural surfaces of the defects.

Osteogenesis in cranial defects: reassessment of the concept of critical size and the expression of TGF-beta isoforms.

Transforming growth factor-betas (TGF-beta) have been demontstrated to be upregulated during osteoblast function in vitro and during cranial suture fusion in vivo. The authors hypothesized that spontaneous reossification of calvarial defects was also associated with upregulation of TGF-beta. The present study was designed to (1) evaluate the concept of a critical-size defect within the calvaria in an adult guinea pig model and (2) investigate the association between the ossification of calvarial defects and TGF-beta upregulation. Paired circular parietal defects with diameters of 3 and 5 mm and single parietal defects with diameters of 8 or 12 mm were made in 45 six-month-old skeletally mature guinea pigs. Three animals per defect size were killed after survival periods of 3 days, 1 week, 4 weeks, 8 weeks, or 12 weeks. New bone ingrowth was evaluated by assessing for linear closure by a traditional linear method and by a modified cross-sectional area method using an image analysis system in which the thickness of new bone was taken into account. Immunohistochemistry was performed using rabbit polyclonal antibodies to localize TGF-beta1, -beta2, and -beta3. All specimens were photographed, and the intensity of immunostaining was graded based on subjective photographic assessment by three independent reviewers. No defect demonstrated any measurable bone replacement after a survival period of 3 days. All 3- and 5-mm defects were completely reossified after 12 weeks based on the linear analysis of new bone, indicating these defects to be less than critical size. However, new bone formation in the 5-mm defects never exceeded a mean of 40 percent by cross-sectional area of new bone. Percent of new bone formation by cross-sectional area was significantly higher within 3-mm defects than in all larger defects 4 weeks after the craniotomy, reaching a mean of 89 percent new bone by 12 weeks. Persistent gaps were noted on linear analysis of the 8- and 12-mm wounds by 12 weeks, and mean percent new bone by cross-sectional area remained below 30 percent. Immunolocalization demonstrated osteogenic fronts at the advancing bone edge and the endocranial side, in which the osteoblasts stained strongly for all isoforms of TGF-beta. The intensity of osteoblast expression waned considerably after the majority of the defect had reossified. These data indicate that histometric analysis based on cross-sectional area more accurately reflects the osteogenic potential of a cranial defect than does linear inspection of defect closure. Although the interpretation of immunolocalization studies is highly subjective, independent assessment by three reviewers indicates that isoforms of TGF-beta were upregulated during a limited "window" of time corresponding to the period of active calvarial reossification, and expression of TGF-beta corresponded to osteoblast activity within osteogenic fronts.

TGF-beta isoforms are differentially expressed in increasing malignant grades of HaCaT keratinocytes, suggesting separate roles in skin carcinogenesis.

The three mammalian isoforms of transforming growth factor-beta (TGF-beta1, -beta2, and -beta3) are potent regulators of cell growth, differentiation, and extracellular matrix deposition. To study their role in skin carcinogenesis, normal human keratinocytes, early (31) and late (310) passage immortalized keratinocytes (HaCaT cells), and five HaCaT-ras clones exhibiting benign (A-5, I-7), malignant (II-4, A-5 RT1), and highly aggressive (A-5 RT3) tumourigenic phenotypes were examined for the expression of TGF-beta isoforms, by immunohistochemistry. This was performed under in vivo conditions, in surface transplants and subcutaneously growing tumours in nude mice. Generally, all tissues that formed keratinized epithelia demonstrated an immunostaining pattern similar to normal human skin. TGF-beta1 was localized to the upper differentiated layers, the stratum granulosum and corneum, in a perimembranous pattern, whereas TGF-beta2 and, weaker, TGF-beta3 immunostaining was present in all suprabasal layers of normal keratinizing epithelia. In contrast, non-keratinizing transplants of non-tumourigenic or highly aggressive cells showed little to no immunoreactivity for TGF-beta1. Whereas TGF-beta2 expression was moderate in the upper layers of non-tumourigenic epithelia, large tumour cells of the malignant HaCaT-ras clones, particularly at the invasion front, were strongly positive for TGF-beta2. TGF-beta3 immunostaining was most pronounced in the stroma of malignant tumours, implying its paracrine induction by the malignant tumour transplants. These results suggest differential functions for each TGF-beta isoform in epidermal carcinogenesis, such that TGF-beta1 is associated with the more differentiated state, TGF-beta2 with highly malignant and invading cells, and TGF-beta3 with tumour stroma formation and angiogenesis. Furthermore, the expression of TGF-betas by both early- and late-stage tumours implies that the isoforms may have distinct functions at different stages of malignancy, supporting their dual role in skin carcinogenesis.

Connective tissue growth factor is a regulator for fibrosis in human chronic pancreatitis.

OBJECTIVE: To evaluate the parameters that mediate fibrogenesis in chronic pancreatitis (CP). BACKGROUND: Connective tissue growth factor (CTGF), which is regulated by transforming growth factor beta (TGF-beta), has recently been implicated in skin fibrosis and atherosclerosis. In the present study, the authors analyzed the concomitant presence of TGF-beta1 and its signaling receptors-TGF-beta receptor I, subtype ALK5 (TbetaR-I(ALK5)), and TGF-beta receptor II (TbetaR-II)-as well as CTGF and collagen type I in the pancreatic tissue of patients undergoing surgery for chronic pancreatitis. PATIENTS AND METHODS: CP tissue samples were obtained from 40 patients (8 women, 32 men) undergoing pancreatic resection. Tissue samples of 25 previously healthy organ donors (12 women, 13 men) served as controls. The expression of TGF-beta1, TbetaR-I(ALK5), TbetaR-II, CTGF, and collagen type I was studied by Northern blot analysis. By in situ hybridization and immunohistochemistry, the respective mRNA moieties and proteins were localized in the tissue samples. RESULTS: Northern blot analysis showed that CP tissue samples exhibited concomitant enhanced mRNA expression of TGF-beta1 (38-fold), TbetaR-II (5-fold), CTGF (25-fold), and collagen type I (24-fold) compared with normal controls. In addition, TbetaR-I(ALK5) mRNA was increased in 50% of CP tissue samples (1.8-fold). By in situ hybridization, TGF-beta1, TbetaR-I(ALK5), and TbetaR-II mRNA were often seen to be colocalized, especially in the ductal cells and in metaplastic areas where atrophic acinar cells appeared to dedifferentiate into ductal structures. In contrast, CTGF was located in degenerating acinar cells and principally in fibroblasts surrounding these areas. Moreover, CTGF mRNA expression levels correlated positively with the degree of fibrosis in CP tissues. CONCLUSION: The concomitant overexpression of CTGF, collagen type I, TGF-beta1, and its signaling receptors in CP suggests that these proteins contribute to enhanced extracellular matrix synthesis and accumulation, resulting finally in the fibrogenesis observed in CP.

Loss of growth regulation by transforming growth factor-beta (TGF-beta) in human cancers: studies on endometrial carcinoma.

Members of the Transforming Growth Factor-beta (TGF-beta) family are one of the few endogenous inhibitors of cell growth. As uncontrolled cellular proliferation is a hallmark of cancer, an important question to address is how cancer cells escape normal growth regulatory mechanisms to become malignant. In this context, components of the TGF-beta growth response pathway are considered to be tumor suppressor genes, as absence of one or more of TGF-beta receptor and signaling proteins cause loss of cell growth regulation through an inability to regulate proteins that directly block cells in G1 phase of the cell cycle. Endometrial carcinoma (ECA) provides an excellent paradigm to study the changes that accompany loss of TGF-beta-mediated growth, control as a function of neoplastic development, since it is generally preceded by complex hyperplasia. Type 1 ECA is characterized as an estrogen-induced cancer, which responds well to progestin therapy. Since it has become increasingly evident that steroids can regulate growth through growth factors, ECA is also an ideal model for investigating the role for gonadal steroids in the loss of TGF-beta growth regulation in the etiopathogenesis of ECA. Thus, hormonal carcinogenesis adds another level of complexity in studying loss of growth regulation in human cancers. The purpose of this review is to 1) provide the most current background information on how TGF-beta functions including its activation, receptors, signal transduction mechanisms, and control of the cell cycle. 2) present recent information that shows how malignant cells subvert the growth inhibitory effects of TGF-beta by incurring defects in every aspect of the pathway that mediates the TGF-beta growth inhibitory response, and 3) describe the putative role for TGF-beta in the oncogenesis of ECA, provided primarily by the results from our laboratory. Understanding the molecular events involved in TGF-beta function in normal cells and its lack of function in tumor cells should identify novel therapeutic targets in human cancers.

Neonatal estrogen exposure alters the transforming growth factor-beta signaling system in the developing rat prostate and blocks the transient p21(cip1/waf1) expression associated with epithelial differentiation.

Exposure of male rats to estrogens during the neonatal period retards prostate branching morphogenesis, blocks epithelial differentiation, and predisposes the adult prostate to hyperplasia and dysplasia. The mechanism of neonatal estrogenization is not well understood. The present study evaluated transforming growth factor-beta (TGFbeta) in the neonatally estrogenized ventral prostate to determine whether this paracrine/autocrine factor may in part mediate the effects ofestrogen on the developing prostate gland. Immunocytochemistry using antibodies against active TGFbeta1 and its latency-associated peptide localized this molecule to the periductal smooth muscle cells in the developing prostate. Although neonatal estrogenization increased the accumulation of total and active TGFbeta1 in the smooth muscle layer as early as day 6 of life, it was physically separated from the epithelial ducts by a proliferating layer of fibroblasts surrounding the basement membrane. RT-PCR demonstrated that alterations in TGFbeta1 levels were not due to alterations in TGFbeta1 transcription. TGFbeta2 and TGFbeta3 were primarily immunolocalized to differentiating epithelial cells in developing prostates, and this was markedly dampened between days 10-30 after neonatal estrogen exposure. Immunocytochemistry for TGFbeta signaling components revealed that neonatal estrogenization transiently reduced TGFbeta type I receptor levels in the prostate epithelium, but not in stroma, between days 6-15, whereas there was no effect on TGFbeta type II receptor. Levels of the intracellular signal Smad2 (52 kDa) were detected in epithelial cells but were not altered after estrogenization. To analyze the functional status of the TGFbeta signaling pathway, immunocytochemistry was performed for p21(cip-1/waf-1), a cyclin-dependent kinase inhibitor that is inducible by TGFbeta1 in the prostate. Transient nuclear localization of p21(cip-1/waf-1) was normally observed in epithelial cells between days 6-15 and was associated with entry of cells into a terminal differentiation pathway. Neonatal estrogenization prevented this transient expression of p21(cip-1/waf-1). The present findings demonstrate that the TGFbeta signaling system is perturbed at several levels in the estrogenized prostate, which may in part account for the epithelial cell differentiation blockade as well as the proliferation of periductal fibroblasts in this model.

Transforming growth factor betas and their signaling receptors in human hepatocellular carcinoma.

BACKGROUND: Transforming growth factor betas (TGF-betas) are multifunctional polypeptides that have been suggested to influence tumor growth. They mediate their functions via specific cell surface receptors (type I ALK5 and type II TGF-beta receptors). The aim of this study was to analyze the roles of the three TGF-betas and their signaling receptors in human hepatocellular carcinoma (HCC). METHODS: HCC tissue samples were obtained from 18 patients undergoing partial liver resection. Normal liver tissues from 7 females and 3 males served as controls. The tissues for histological analysis were fixed in Bouin's solution and paraffin embedded. For RNA analysis, freshly obtained tissue samples were snap frozen in liquid nitrogen and stored at -80 degrees C until used. Northern blot analysis was used in normal liver and HCC to examine the expression of TGF-beta1, -beta2, -beta3 and their receptors: type I ALK5 (TbetaR-I ALK5), type II (TbetaR-II), and type III (TbetaR-III). Immunohistochemistry was performed to localize the corresponding proteins. RESULTS: All three TGF-betas demonstrated a marked mRNA overexpression in HCC in comparison with normal controls, whereas the levels of all three TGF-beta receptors showed no significant changes. Intense TGF-beta1, TGF-beta2, and TGF-beta3 immunostaining was found in hepatocellular carcinoma cells and in the perineoplastic stroma with immunohistochemistry, whereas no or mild immunostaining was present in the normal liver. For TbetaR-I ALK5 and TbetaR-II, the immunostaining in both HCC and normal liver was mild to moderate, with a slightly higher intensity in the normal tissues. CONCLUSION: The upregulation of TGF-betas in HCC suggests an important role for these isoforms in hepatic carcinogenesis and tumor progression. Moreover, the localization of the immunoreactivity in both malignant hepatocytes and stromal cells suggests that TGF-betas act via autocrine and paracrine pathways in this neoplasm.

Increased levels of transforming growth factor-beta in HIV-associated nephropathy.

BACKGROUND: Human immunodeficiency virus-associated nephropathy (HIVAN) is a renal disease of unknown pathogenesis. Recent evidence suggests that the fibrogenic cytokine transforming growth factor-beta (TGF-beta) might be involved. We hypothesized that overproduction of TGF-beta in the kidney might be involved in the pathogenesis of HIVAN. METHODS: The mRNA and protein expression of TGF-beta isoforms, TGF-beta 1, TGF-beta 2, and TGF beta 3, deposition of matrix proteins induced by TGF-beta, and levels of HIV Tat protein were studied in HIVAN. Controls included normal and diseased kidneys from HIV-positive and -negative patients. The ability of Tat to induce production of TGF-beta and matrix proteins was also studied in human mesangial cells. RESULTS: Normal kidneys, thin basement membrane nephropathy, and minimal change disease were negative for the three TGF-beta isoforms and Tat. In HIVAN, levels of TGF-beta isoforms and Tat were significantly increased, along with the expression of TGF-beta mRNA and deposition of matrix proteins stimulated by TGF-beta. Increased levels of TGF-beta isoforms, but not Tat, were also found in other glomerular diseases characterized by matrix accumulation. HIV infection, in the absence of HIVAN, was not associated with an increase in TGF-beta or Tat expression. Tat stimulated the expression and production of TGF-beta 1 and matrix proteins by human mesangial cells. CONCLUSIONS: Our findings suggest that overproduction of TGF-beta is involved in the pathogenesis of HIVAN.

Comparison of the fibrin-binding activities in the N- and C-termini of fibronectin.

Fibronectin (Fn) binds to fibrin in clots by covalent and non-covalent interactions. The N- and C-termini of Fn each contain one non-covalent fibrin-binding site, which are composed of type 1 (F1) structural repeats. We have previously localized the N-terminal site to the fourth and fifth F1 repeats (4F1.5F1). In the current studies, using proteolytic and recombinant proteins representing both the N- and C-terminal fibrin-binding regions, we localized and characterized the C-terminal fibrin-binding site, compared the relative fibrin-binding activities of both sites and determined the contribution of each site to the fibrin-binding activity of intact Fn. By fibrin-affinity chromatography, a protein composed of the 10F1 repeat through to the C-terminus of Fn (10F1-COOH), expressed in COS-1 cells, and 10F1-12F1, produced in Saccharomyces cerevisiae, displayed fibrin-binding activity. However, since 10F1 and 10F1.11F1 were not active, the presence of 12F1 is required for fibrin binding. A proteolytic fragment of 14.4 kDa, beginning 14 residues N-terminal to 10F1, was isolated from the fibrin-affinity matrix. Radio-iodinated 14.4 kDa fibrin-binding peptide/protein (FBP) demonstrated a dose-dependent and saturable binding to fibrin-coated wells that was both competitively inhibited and reversed by unlabelled 14.4 kDa FBP. Comparison of the fibrin-binding affinities of proteolytic FBPs from the N-terminus (25.9 kDa FBP), the C-terminus (14.4 kDa) and intact Fn by ELISA yielded estimated Kd values of 216, 18 and 2.1 nM, respectively. The higher fibrin-binding affinity of the N-terminus was substantiated by the ability of both a recombinant 4F1.5F1 and a monoclonal antibody (mAb) to this site to maximally inhibit biotinylated Fn binding to fibrin by 80%, and by blocking the 90% inhibitory activity of a polyclonal anti-Fn, by absorption with the 25.9 kDa FBP. We propose that whereas the N-terminal site appears to contribute to most of the binding activity of native Fn to fibrin, the specific binding of the C-terminal site may strengthen this interaction.

The role for transforming growth factor-beta (TGF-beta) in human cancer.

Uncontrolled cellular proliferation is a hallmark of cancer. Thus, a relevant and important question is how cancer cells have escaped from normal growth regulatory mechanisms to become malignant and, further, what events favor progression and metastasis. Growth regulatory proteins of the transforming growth factor-beta family (TGF-beta) are one of the few classes of endogenous inhibitors of cell growth. Contrary to the first notion that these proteins may be downregulated in cancer cells to promote their growth, generally it has been otherwise found that there is a marked increase in the expression of TGF-beta mRNA and protein in human cancers (in vivo), including those of the pancreas, colon, stomach, lung, endometrium, prostate, breast, brain, and bone. Furthermore, in many of these cancers high expression correlates with more advanced stages of malignancy and decreased survival. The increased expression of TGF-beta is usually accompanied by a loss in the growth inhibitory response to TGF-beta. For example, certain tumor cells in culture (i.e., colon carcinoma and glioblastoma multiforme) demonstrate a progressive loss of the growth inhibitory response to TGF-beta that varies directly with the malignant stage of the original tumor, and the most aggressive forms actually switch to being autocrine and/or paracrine growth stimulated by TGF-beta. The study of the molecular events associated with the escape of tumor cells from growth regulation by TGF-beta has provided insight into mechanisms underlying carcinogenesis. The mechanisms for upregulation of TGF-beta are unknown. However, once malignant cells lose their growth inhibitory response to TGF-beta and produce massive amounts of these proteins, the increased expression of TGF-beta provides a selective advantage for tumor cell survival as TGF-betas are also angiogenic and have potent immunosuppressive effects, including specifically inhibiting tumoricidal natural and lymphocyte-activated killer cells. In light of the significant role for TGF-betas in regulating cell growth, it is not surprising that in more recent years studies have shown that specific genetic alterations involved in the signaling pathway for TGF-beta-mediated growth inhibition have occurred in many human cancers. Specific defects in TGF-beta receptors, TGF-beta-related-signal transduction/gene activation, and TGF-beta-regulated cell cycle proteins, have all been implicated in the oncogenesis of many human cancers. In this context, components of the TGF-beta growth response pathway are considered to be tumor suppressor genes, as absence (or malfunction) of one or more receptors or signaling proteins would have the potential to cause loss of growth regulation. More recently, the posttranslational reduction of levels of the cyclin-dependent kinase inhibitor (CKI), p27kip1, which mediates TGF-beta growth inhibition, provides an additional means for cancer cells to escape negative growth regulation by TGF-beta. This review provides background information on TGF-beta and updates the status of our knowledge of the role for TGF-beta in specific human malignancies. Understanding the molecular events involved in TGF-beta function in normal cells and its lack of function in tumor cells should identify novel therapeutic targets in human cancers.

A subset of metastatic human colon cancers expresses elevated levels of transforming growth factor beta1.

Although transforming growth factor (TGF)-beta1 is a potent growth inhibitor of normal epithelial cells including colonocytes, TGF-beta1 has also been implicated as an enhancer of colon cancer metastasis. Decreasing TGF-beta1 protein levels in the metastatic U9 colon cancer cell line by antisense methodology decreased both U9 cell metastasis to the liver and s.c. tumor formation in a nude mouse system, and the tumors that did arise had regained TGF-beta1 expression (F. Huang et al, Cell Growth Differ., 6: 1635-1642, 1995). In addition, in a clinical immunohistochemistry study, colon cancers with elevated TGF-beta1 protein levels were found to be 18 times more likely to recur as distant metastases than colon cancers expressing low TGF-beta1 levels, after resection of the primary tumor (E. Friedman et al, Cancer Epidemiol. Biomark. Prev., 4:549-554, 1995). Because both studies implicated TGF-beta1 in colon cancer metastasis, we wished to know whether a selection bias for TGF-beta1 was maintained in metastatic cells or was only a property of the primary site tumors that were likely to metastasize. TGF-beta1 levels were measured using two different antibodies in paired primary site cancers and their metastases by immunohistochemistry and, in selected cases, by Western blot analysis. In 16 of 21 cases (76%) with antibody G and 23 of 31 cases (74%) with antibody P, higher expression of TGF-beta1 was found in colon cancer cells invading local lymph nodes compared with primary site colon cancer cells, or (2 and 6 cases, respectively) high TGF-beta1 expression in the primary site cancer was maintained in invasive cells. Analysis by Western blotting using both antibodies also demonstrated that higher levels of TGF-beta1 protein were found in metastases compared with the primary site tumor or normal tissue. Additional cases of paired primary site colon cancer, local lymph node metastases, and cancer cells metastasizing to distant sites were examined. In six of eight such cases (75%), TGF-beta1 levels were increased in both invasive cell populations compared with the primary site cancer (five cases), or high levels in the primary site cancer were maintained in the metastatic cells (one case). These data suggest that TGF-beta1 plays a role in promoting colon cancer metastasis throughout the metastatic process in roughly 75% of cases. TGF-beta1 may increase metastasis by paracrine mechanisms, such as suppression of local immune response or increased angiogenesis, as was seen with the U9 cell line. In those cancers with nonmutated TGF-beta receptors and nonmutated smad proteins like U9 cells, TGF-beta1 could also act in an autocrine manner to increase invasion by increasing cell motility (Hsu et al., Cell Growth Differ., 5: 267-275, 1994).

Proteoglycan distribution in lesions of atherosclerosis depends on lesion severity, structural characteristics, and the proximity of platelet-derived growth factor and transforming growth factor-beta.

The accumulation of proteoglycans (PGs) in atherosclerosis contributes to disease progression and stenosis and may partly depend on local regulation by growth factors such as platelet-derived growth factor (PDGF) and transforming growth factor (TGF)-beta. In this study, the distribution of the major extracellular PGs is compared with that of PDGF and TGF-beta isoforms in developing lesions of atherosclerosis from hypercholesterolemic nonhuman primates. Strong immunostaining for decorin, biglycan, versican, and hyaluronan is observed in both intermediate and advanced lesions. Perlecan staining is weak in intermediate lesions but strong in advanced lesions in areas bordering the plaque core. Immunostaining for PDGF-B and TGF-beta1 is particularly prominent in macrophages in intermediate and advanced lesions. In contrast, TGF-beta2 and TGF-beta3 and PDGF-A are present in both macrophages and smooth muscle cells. Overall, PG deposits parallel areas of intense growth factor immunostaining, with trends in relative localization that suggest interrelationships among certain PGs and growth factors. Notably, decorin and TGF-beta1 are distributed similarly, predominantly in the macrophage-rich core, whereas biglycan is prominent in the smooth muscle cell matrix adjoining TGF-beta1-positive macrophages. Versican and hyaluronan are enriched in the extracellular matrix adjacent to both PDGF- and TGF-beta1-positive cells. These data demonstrate that PG accumulation varies with lesion severity, structural characteristics, and the proximity of PDGF and TGF-beta.

Enhanced expression of TGF-betas and their receptors in human acute pancreatitis.

OBJECTIVES: To determine which mechanisms are involved in pancreatic remodeling, repair, and fibrosis after acute necrotizing pancreatitis (NP) in humans. SUMMARY BACKGROUND DATA: Transforming growth factor betas (TGF-betas) are multifunctional polypeptides that have been implicated in the regulation and formation of extracellular matrix and fibrosis. They exert their functions by binding to specific receptors. In this study, we analyze the expression of TGF-beta1, TGF-beta2, and TGF-beta3 and their receptors type I (Tbeta-RI [ALK5]), type II (Tbeta-RII), and type III (Tbeta-RIII) in NP. PATIENTS: Pancreatic tissue samples were obtained from 6 female and 8 male patients with a median age of 65 years (range, 37 to 77 years) undergoing surgery for NP. The median Ranson score of the patients was 6 (range, 2 to 9). The operation was performed a median 5.5 days (range, 4 to 17 days) after the onset of acute pancreatitis. Pancreatic tissue obtained from 12 previously healthy organ donors (6 male, 6 female; median age of 43 years) served as controls. METHODS: The expression of TGF-beta1, TGF-beta2, TGF-beta3, Tbeta-RI (ALK5), Tbeta-RII, Tbeta-RIII, and collagen type I mRNA was analyzed by Northern blot analysis. In addition, immunohistochemical analysis using polyclonal antibodies was performed to detect TGF-beta1, TGF-beta2, TGF-beta3, Tbeta-RI (ALK5), and Tbeta-RII. RESULTS: Northern blot analysis showed an increase in TGF-betas and their receptors in NP tissue samples compared with samples from normal controls. The increase was 3.5-fold for TGF-beta1 (p < 0.05), 2.7-fold for TGF-beta2 (p < 0.05), 3.5-fold for TGF-beta3 (p < 0.05), 10-fold for Tbeta-RI (ALK5) (p < 0.05), 5.7-fold for Tbeta-RII (p < 0.05), and 1.4-fold for Tbeta-RIII (not significant). Collagen type I mRNA was also markedly increased in NP samples and correlated with the level of TGF-betas. Immunohistochemical analysis demonstrated intense TGF-beta1, TGF-beta2, TGF-beta3, Tbeta-RI (ALK5), and Tbeta-RII immunoreactivity in the remaining acinar and ductal cells in most NP samples; in the normal control pancreas, there was weak to moderate immunoreactivity for these factors only in some acinar cells and a few ductal cells. CONCLUSION: The marked increase in expression of TGF-betas and their signaling receptors Tbeta-RI (ALK5) and Tbeta-RII suggests a role for TGF-betas in the repair process after the onset of NP in humans and raises the possibility that TGF-betas might be involved in tissue remodeling and the fibrotic reaction that occurs in the pancreas after necrosis.

Transforming growth factor betas and their receptors in human liver cirrhosis.

BACKGROUND: Transforming growth factor betas (TGF-betas) are a group of homologous polypeptides that exert pleiotropic effects on various cell types and stimulate the formation of extracellular matrix and fibrosis. To evaluate whether TGF-beta isoforms (TGF-beta1, TGF-beta2 and TGF-beta3) and their receptors (types I-III) are also of importance in the pathophysiology of liver cirrhosis, we analysed their concomitant expression and localization in human liver cirrhosis. PATIENTS: Cirrhotic liver tissue samples were obtained from 17 patients (four women, 13 men) with a median age of 41 years (range 22-67). Normal liver tissues from ten patients (seven women, three men) with a median age of 55 years (range 45-75) served as controls. METHODS: The tissues were fixed in Bouin's solution and paraffin-embedded for histological analysis. For RNA analysis, freshly obtained tissue samples were snap-frozen in liquid nitrogen and stored at -80 degrees C until analysed. Northern blot analysis was used to examine the expression of TGF-beta1, beta2 and beta3 and their receptors, type I (TbetaR-I), type II (TbetaR-II) and type III (TbetaR-III). Immunohistochemistry was performed to determine the localization of the corresponding proteins in the normal and the cirrhotic liver. RESULTS: Northern blot analysis revealed enhanced expression (P < 0.05) of TGF-beta1 (twofold increase), TGF-beta2 (threefold increase) and TGF-beta3 (8.5-fold increase) and of TbetaR-II (threefold increase) mRNA in liver cirrhosis in comparison with normal controls. In contrast, TbetaR-I (ALK-5) and TbetaR-III mRNA expression showed no significant changes. No TGF-beta isoform immunoreactivity was present in hepatocytes in either normal livers or in liver cirrhosis. However, in liver cirrhosis, intense TGF-beta1 immunoreactivity was present in bile duct and ductular epithelial cells (including ductular proliferations) and in inflammatory cells. In a few sinusoidal lining cells, faint TGF-beta1 and moderate TGF-beta2 immunoreactivity was present. TGF-beta3 immunostaining was present in bile duct and ductular epithelial cells, in inflammatory cells and in fibroblast-like spindle cells in liver cirrhosis. For TbetaR-I and TbetaR-II, the immunoreactivity was localized in hepatocytes and biliary cells in normal and cirrhotic liver tissues, with higher intensity for TbetaR-II in the cirrhotic liver. CONCLUSION: Enhanced expression of all three TGF-bea isoforms and of TbetaR-II in liver cirrhosis suggests their involvement in this fibrotic disorder. The higher immunoreactivity of the three TGF-beta isoforms in the bile duct epithelial cells in cirrhotic tissues suggests a possible role of these cells in the pathogenesis of liver cirrhosis.

Expression of transforming growth factor-beta (TGF-beta) isoforms in osteosarcomas: TGF-beta3 is related to disease progression.

BACKGROUND: Transforming growth factor-beta (TGF-beta) is a multipotent growth factor affecting development, homeostasis, and tissue repair. In addition, increased expression of TGF-beta has been reported in different malignancies, suggesting a role for this growth factor in tumorigenesis. METHODS: Using immunohistochemistry, the expression, prevalence, and distribution of TGF-beta isoforms were evaluated in 25 high grade human osteosarcomas. The Cox proportional hazards models and Kaplan-Meier curves were calculated correlating disease free survival with TGF-beta expression. RESULTS: Expression of one or more TGF-beta isoforms was found in all the osteosarcomas. Immunoreactivity for TGF-beta1 and TGF-beta3 generally was stronger than for TGF-beta2. The cytoplasm of the tumor cells showed stronger staining than their surrounding extracellular stroma. Most notably, osteoclasts showed strong to intense staining for all three isoforms. In 11 of 25 specimens angiogenic activity was noted with staining of multiple small vessels in the tumor stroma. Expression of TGF-beta3, but not of TGF-beta2 or TGF-beta1, related to disease progression, such that there was a statistically significant decrease in the disease free interval as the immunoreactivity for TGF-beta3 increased. CONCLUSIONS: All osteosarcomas expressed TGF-beta in the cytoplasm of the tumor cells as well as in their extracellular stroma. The presence of TGF-beta in the endothelial and perivascular layers of small vessels in the tumor stroma suggests angiogenic activity of this growth factor. The expression of TGF-beta3 was correlated strongly with disease progression (P = 0.027). These data suggest that increased expression of TGF-beta isoforms, especially TGF-beta3, may play a role in osteosarcoma progression.

Immunohistochemical localization of transforming growth factor beta isoforms in asbestos-related diseases.

Transforming growth factor beta (TGF-beta), a multifunctional cytokine and growth factor, plays a key role in scarring and fibrotic processes because of its ability to induce extracellular matrix proteins and modulate the growth and immune function of many cell types. These effects are important in inflammatory disorders with fibrosis and cancer. The asbestos-related diseases are characterized by fibrosis in the lower respiratory tract and pleura and increased occurrence of lung cancer and mesothelioma. We performed immunohistochemistry with isoform-specific antibodies to the three TGF-beta isoforms on 16 autopsy lungs from Quebec, Canada, asbestos miners and millers. There was increased immunolocalization of all three TGF-beta isoforms in the fibrotic lesions of asbestosis and pleural fibrosis. The hyperplastic type II pneumocytes contained all three isoforms. By contrast, there was differential spatial immunostaining for the TGF-beta isoforms in malignant mesothelioma, with TGF-beta 1 in the stroma but TGF-beta 2 in the tumor cells. These data are consistent with an important role for TGF-beta in accumulation of extracellular matrix and cell proliferation in asbestos-related diseases.

Exogenous and endogenous transforming growth factors-beta influence elastin gene expression in cultured lung fibroblasts.

Elastin, an important structural protein of the extracellular matrix, confers elastic properties on the pulmonary alveolar interstitium. In the alveolar wall, elastin is primarily produced postnatally by fibroblasts. The mechanisms that regulate lung fibroblast (LF) elastin gene expression have not been completely defined, although both transcriptional and posttranscriptional mechanisms appear to be involved. Transforming growth factors-beta (TGF-beta s) have been shown to increase elastin production by cultured neonatal rat LF. Analyses of elastin gene transcription and mRNA stability indicate that exogenous TGF-beta 1 increases the half-life of tropoelastin mRNA by 1.5-fold and does not alter elastin gene transcription. Interference with the functions of endogenous TGF-beta 1 in cultured LF, through the addition of neutralizing antibodies or antisense oligodeoxynucleotides, decreases tropoelastin and tropoelastin mRNA production by these cells. The content of total (latent plus active) TGF-beta s was approximately 4.5-fold greater in lungs obtained from rats on postnatal day 8 than in lungs obtained from adults. These findings indicate that endogenous TGF-beta s, in cultured LF, regulate elastin gene expression, most likely by a posttranscriptional mechanism. Since others have shown that elastin mRNA appears to have a longer half-life in neonatal than in adult rat lungs, we hypothesize that the higher content of TGF-beta s could contribute to the greater elastin mRNA stability in neonatal lungs.

Differential localization of transforming growth factor-beta isoforms in human gastric mucosa and overexpression in gastric carcinoma.

Transforming growth factor beta (TGF-beta) isoforms comprise a family of multifunctional polypeptide growth factors that either inhibit or stimulate cell proliferation. We examined TGF-beta expression in normal human gastric mucosa and carcinoma. The distribution and expression of TGF-beta isoforms in 4 normal mucosa samples from organ donors, in 12 normal mucosa samples adjacent to gastric cancer and in 12 gastric carcinomas were examined using immunohistochemistry and Northern blot analysis. Because TGF-beta s regulate collagen expression, collagen type I alpha1 mRNA amounts were also examined. Immunohistochemical analysis of normal human gastric tissue samples indicated that TGF-beta1 localized principally in parietal cells but also in some surface mucus cells, TGF-beta2 was present exclusively in chief cells and TGF-beta3 was present in parietal, chief and mucus cells. In the gastric cancers, strong colocalization of TGF-beta1, -beta2 and -beta3 was evident in the cancer cells. Northern blot analysis indicated that, compared to normal gastric tissue, gastric cancers showed a 4.8- and 6-fold increase in mRNA amounts encoding TGF-beta1 and TGF-beta3, respectively. In contrast, TGF-beta2 mRNA amounts were comparable in both groups. Northern blot analysis showed a 10-fold increase in human collagen type I alpha1 mRNA amounts compared to normal gastric tissue. These findings imply a role forTGF-beta s in normal human gastric mucosa function, and raise the possibility that the aberrant colocalization and overexpression of all 3 TGF-beta isoforms in human gastric cancer cells in vivo may contribute to the pathobiology of gastric carcinoma.