Immunoreactive TGF-alpha Research Articles

Transforming growth factor α, amphiregulin and cripto-1 are frequently expressed in advanced human ovarian carcinomas

The expression of transforming growth factor alpha (TGFalpha), amphiregulin (AR) and cripto-1 (CR-1) was assessed by immunohistochemistry in 83 specimens (59 primary ovarian tumors and 24 extra-ovarian carcinomas) that were obtained from 68 ovarian carcinoma patients. Within the 59 primary tumors, 54 (92%) expressed immunoreactive TGFalpha, 45 (76%) expressed AR, and 28 (47%) expressed CR-1. The expression of AR and CR-1 mRNAs in the ovarian carcinomas was also demonstrated by RT-PCR analysis. Seventeen extra-ovarian specimens (71%) were found to express CR-1, whereas AR and TGFalpha were expressed respectively in 21 (87%) and 22 (92%) extra-ovarian tissues. In 15 cases for whom both ovarian and extra-ovarian tissues were available, a statistically significant higher expression of CR-1 was found in extra-ovarian specimens. A statistically significant correlation was found between AR expression in the ovarian carcinomas and both low grade and low proliferative activity. Finally, expression of TGFalpha was predictive of longer progression-free survival. These data strongly suggest that the EGF-related peptides might be involved in the pathogenesis and outcome of human ovarian cancer.

Activation of genes for growth factors and cyclooxygenases in rat gastric mucosa during recovery from stress damage

Growth factors and prostaglandins protect the gastric mucosa against stress-induced lesions but their role in the recovery of the mucosa from these lesions has been little studied. We evaluated gastric mucosa lesions, gastric blood flow, mucosal generation of prostaglandin E2 and mucosal gene expression of epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) as well as constitutive prostaglandin cyclooxygenase-1 and inducible cyclooxygenase-2 and the effect of the inhibition of these enzymes on the recovery of mucosa from the stress-induced lesions. Rats were exposed to 3.5 h of water immersion and restraint stress and killed at 0, 2, 4, 6, 8, 12 and 24 h after stress. The number of gastric lesions was determined and gastric blood flow was measured by H2-gas clearance. Gastric acid secretion was tested in separate gastric fistula rats. Gastric mucosa biopsies were taken for determination of immunoreactive EGF and TGF alpha. Expression of EGF and TGF alpha mRNA and cyclooxygenase-1 and cyclooxygenase-2 mRNA was also determined by reverse-transcriptase polymerase chain reaction. The number of gastric lesions induced by 3.5 h stress averaged approximately 20 per rat and declined significantly at 2, 4, 6, 8 and 12 h, to disappear almost completely after 24 h. This was accompanied by a gradual rise in gastric blood flow, mucosal generation of prostaglandin E2 and mucosal EGF and TGF alpha contents, while the increased gastric acid secretion returned to normal. In the intact mucosa, EGF mRNA was not detected but TGF alpha mRNA was found in measurable amounts. Following exposure to stress, the expression of both these factors was significantly increased. Similarly, the expression of cyclo-oxygenase-1 and cyclooxygenase-2 mRNA was detected in the oxyntic mucosa at all time intervals after exposure to stress. Indomethacin (5 mg/kg i.p.), an inhibitor of cyclooxygenase-1 and cyclooxygenase-2, and meloxicam (1 mg/kg i.p.), an inhibitor of cyclooxygenase-2, both prolonged the healing of stress lesions and reduced the gastric blood flow, while enhancing gastric acid secretion at all times tested. We conclude that healing of stress lesions results in the restoration gastric blood flow and mucosal prostaglandin generation and that these effects are accompanied by overexpression of EGF and TGF alpha as well as cyclooxygenase-1 and cyclooxygenase-2 mRNA and by increased biosynthesis of gastroprotective prostaglandin.

Mucosal expression and luminal release of epidermal and transforming growth factors in patients with duodenal ulcer before and after eradication of Helicobacter pylori.

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF alpha) are potent gastric acid inhibitors and stimuli of mucosal growth and protection but their involvement in Helicobacter pylori associated duodenal ulcer has been little examined. To assess gastric acid secretion, plasma gastrin concentrations, mucosal content of EGF and TGF alpha, and mucosal expression of these peptides and their receptor (EGFr) as well as salivary and gastric luminal release of EGF under basal conditions and after pentagastrin stimulation in 10 healthy subjects and in 25 H pylori positive patients with duodenal ulcer before and after two weeks of triple anti-H pylori therapy and four weeks after the termination of this therapy. Pentagastrin stimulation caused a significant increase in salivary and gastric release of EGF both in healthy controls and patients with duodenal ulcers but in the patients, the eradication of H pylori resulted in several fold higher gastric luminal (but not salivary) EGF release than before the anti-H pylori therapy. Mucosal contents of immunoreactive EGF and TGF alpha and mucosal expression of EGF, TGF alpha, and EGFr in H pylori positive patients with duodenal ulcer were significantly higher than those in healthy H pylori negative controls and this increase persisted after eradication of H pylori. Basal plasma gastrin was significantly reduced after two weeks of triple therapy and four weeks after the H pylori eradication all ulcers were completely healed. (1) H pylori infection in patients with duodenal ulcer was accompanied by enhanced plasma gastrin and increased mucosal content and expression of TGF alpha, EGF, and EGFr; (2) H pylori eradication resulted in ulcer healing, reduction in plasma gastrin, and enhancement of gastric (but not salivary) luminal release of EGF, particularly after pentagastrin stimulation; and (3) enhanced mucosal content and expression of TGF alpha, EGF, and EGFr and increased luminal release of EGF may contribute to ulcer healing after eradication of H pylori.

Impact of Helicobacter pylori colonization on immunoreactive epidermal growth factor and transforming growth factor-alpha in gastric juice. Its potential pathogenetic implications.

Epidermal growth factor (EGF), pivotal in mucosal protection, is partly degraded proteolytically at low pH in the gastric milieu; gastric acid secretion, on the other hand, remains influenced by H. pylori colonization. The aim of this study, therefore, was to evaluate the impact of low pH and H. pylori colonization status on immunoreactive EGF and the other member of EGF-family, immunoreactive transforming growth factor-alpha (TGF-alpha). Eighteen patients with nonulcer dyspepsia (NUD) colonized by H. pylori and 55 NUD patients without H. pylori colonization were investigated. Gastric juice samples were aspirated at the beginning of the endoscopy procedure and immediately placed on ice, and their pH was recorded. The measurement of immunoreactive EGF and TGF-alpha was performed using commercially available radioimmunoassays (RIAs) after adjustment of pH to neutral using an assay buffer. Statistical analysis was performed using sigma-Stat for Windows. The concentration of immunoreactive EGF in patients with NUD colonized by H. pylori was 80% lower (P < 0.02) than in those without H. pylori and in both groups immunoreactive EGF was significantly lower when the pH of gastric juice was below 4.0. The concentration of immunoreactive EGF in H. pylori(+) and H. pylori(-) patients was similar when the pH of aspirated gastric juice was above 4.0. However, with gastric juice pH < 4.0, the EGF concentration was 64% lower in H. pylori(+) patients than H. pylori(-) patients (P < 0.05). In general, the concentration of immunoreactive TGF-alpha in gastric juice was unaffected by H. pylori colonization or pH of gastric juice. It is concluded that: (1) significantly lower immunoreactive EGF concentrations in patients with pH below 4.0 indicate that immunoreactive EGF but not immunoreactive TGF-alpha is affected by an acidic gastric milieu; (2) the further reduction of gastric juice immunoreactive EGF at pH below 4.0 in patients colonized by H. pylori suggests that this microorganism may elaborate factors that accelerate its proteolytic degradation or inhibit its rate of synthesis and/or secretion; and (3) this diminished content of immunoreactive EGF at low pH, especially in patients colonized by H. pylori, may facilitate the development and/or progression of mucosal damage.

Subcellular Localization of Transforming Growth Factor-α in Human Eosinophil Granulocytes

Eosinophils are involved in the inflammatory response seen in allergy and helminthic infestations. Eosinophils synthesize transforming growth factor-alpha (TGF-alpha), which may play a role in the development of the characteristic fibrosis seen in longstanding high eosinophilia. Using immunoelectron microscopic techniques, eosinophils from peripheral blood of healthy individuals and from one patient with high eosinophilia showed presence TGF-alpha in matrix of the specific crystalloid-containing granules. In cryosections, TGF-alpha was also visualized in a vesicular compartment of the cytoplasm. In double-labeling experiments, the TGF-alpha of this latter compartment did not colocalize with CD63, a marker for lysosomes, nor with albumin of secretory vesicles. In extracts from eosinophils, obtained from healthy donors, immunoreactive TGF-alpha could be detected by enzyme-linked immunosorbent assay-technique. In addition, sera from two patients with high eosinophilia showed TGF-alpha concentrations of 1.5 ng/mL and 164 pg/mL, respectively, whereas TGF-alpha could not be detected in serum from healthy controls. In conclusion, TGF-alpha is present in the specific granules, and in an additional vesicular compartment of the cytoplasm of eosinophils.

Immunohistochemical localization of transforming growth factor-alpha in suckling porcine intestine.

The distribution of transforming growth factor-alpha (TGF alpha), a member of the epidermal growth factor (EGF) family, was studied immunohistochemically in small intestinal tissues of suckling pigs which were 7, 14 and 21 days of age. TGF alpha immunostaining was similar in villous epithelium in all intestinal regions of all ages examined, and was diffuse throughout the epithelial cytoplasm and more prominent in the apical and brush-border regions of the cells. Cytoplasmic immunoreactive TGF alpha was also identified in crypt epithelial cells; the pattern and extent of immunostaining differed among intestinal regions and ages. In all cases, the relative number of TGF alpha-immunopositive crypt epithelial cells was fewer than the number of immunonegative cells within the compartment. In duodenal and jejunal segments, relative numbers of immunopositive crypt epithelial cells were greater in 14- and 21- than in 7-day-old pigs. In all 7-day-old pigs, a relatively greater number of immunopositive epithelial cells was present in the jejunal crypts than in the duodenal crypts. Intracellular TGF alpha immunostaining was present within Peyer's patches of distal jejunum and ileum, and is a previously unreported finding. The presence of TGF alpha immunoreactive protein within small intestinal crypt epithelium has not been previously described in any species, and may be unique to suckling animals or, alternatively, the porcine species. These data suggest that TGF alpha may be an endogenous ligand for the EGF receptor in suckling porcine intestine. Increased expression of TGF alpha in suckling pigs during the period in which marked structural and functional changes occur within the small intestinal mucosa suggests a role for this growth factor in remodelling and maturation of the neonatal mucosa.

Epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor localization in the baboon (Papio anubis) oviduct during steroid treatment and the menstrual cycle.

Polypeptide growth factors may modulate the actions of estrogen (E2) and progesterone (P) in reproductive tissues in an autocrine/paracrine manner. The objective of this study was to determine whether the baboon oviduct contains epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha), and EGF receptor (EGF-R) and whether changes in their expression are correlated with various hormonal states. Oviductal tissue was obtained from adult female baboons (Papio anubis) after oophorectomy and steroid treatment, and during the menstrual cycle. Ampullary regions were fixed in Bouin's fixative and embedded in paraffin for immunocytochemistry using rabbit polyclonal antibodies against EGF and EGF-R, and mouse monoclonal antibody against TGF alpha. Both EGF and EGF-R were present in all tissue compartments (most strongly in the epithelium, followed by smooth muscle and stroma) at all reproductive stages and showed similar staining patterns. However, the most intense immunoreactive product was found in the tissue obtained from the E2-treated and late follicular phase animals. At this time, intense staining was present in the apical regions of the mature ciliated cells, whereas the stain was dispersed uniformly over the cytoplasm of all other cell types. Immunoreactive TGF alpha was limited primarily to the nonciliated epithelial cells, and staining was most intense in the E2-treated and late follicular phase tissues. Transforming growth factor-alpha formed intense perinuclear deposits in the mature secretory cells, an area that corresponds to the Golgi region. No immunoreactive product was observed for any of these proteins when preimmune serum was substituted for the primary antibody or when the primary antibody was preabsorbed with antigen. In summary, EGF, TGF alpha, and EGF-R are present in the ampulla of the baboon oviduct. Moreover, the localization and intensity of immunoreactive product are dependent on cell type and hormonal state. These data are consistent with the concept that EGF, TGF alpha, and EGF-R may be regulated by E2 and P and thus may play a role in cell differentiation and function. In addition, the specific localization of TGF alpha suggests that this growth factor may be synthesized for release from the secretory cells and thus may also function as a modulator of gamete/embryo viability and development.

Expression of messenger ribonucleic acid and presence of immunoreactive proteins for epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha) and EGF/TGF alpha receptors and 125I-EGF binding sites in human fallopian tube.

Reverse transcription polymerase chain reaction (RT-PCR) revealed that the Fallopian tubes express epidermal growth factor (EGF), transforming growth factor (TGF alpha), and EGF receptor (EGF-R) mRNA. The RT-PCR product was verified by restriction enzyme digestion analysis. Immunohistochemically, EGF, TGF alpha, and EGF-R were localized in Fallopian tubes by use of specific antibodies to human EGF, mature fragments of human TGF alpha, and monoclonal antibodies to the extracellular binding domain of EGF-R. The tubal epithelial cells were the primary site of immunoreactive EGF, TGF alpha, and EGF-R, which were present to a lesser extent in the stromal cells, smooth muscle cell layers, fibroblasts of serosal tissue, and arterial endothelial and smooth muscle cells. Using antibodies generated against the amino and carboxy termini of TGF alpha precursor produced a similar cellular distribution to that observed for mature TGF alpha. The intensity of immunoreactive TGF alpha with these antibodies was similar to that seen with EGF. The ciliated and nonciliated epithelial cells in the ampullary and isthmus regions immunostained with similar intensity for EGF, TGF alpha, and EGF-R. The immunostaining for EGF, TGF alpha, and EGF-R was cycle-dependent, was considerably higher during late proliferative and early-to-mid-secretory phases than during early proliferative and late secretory phases of the menstrual cycle, and was reduced during the postmenopausal period. Specimens obtained 5-12 yr after tubal ligation immunostained for EGF, TGF alpha, and EGF-R similarly to sections from unligated tubes taken during the same phase of the cycle. Quantitative autoradiography of 125I-EGF binding generated a pattern similar to that of immunostaining for EGF-R binding. Net grain density/100 microns 2 calculated for different cell types indicated that the epithelial cells had a significantly higher grain density than did other tubal cell types (p < 0.05) without the cycle dependency seen in the immunohistochemical study. In summary, the results demonstrate that the human Fallopian tube expresses mRNA and contains immunoreactive proteins for EGF, TGF alpha, and EGF-R as well as binding sites for 125I-EGF. The cycle dependency and lower immunostaining in postmenopausal tubes suggest a potential regulation of their expression by ovarian steroids. The results imply the importance of EGF/TGF alpha in a variety of tubal biochemical and physiological functions and possibly early embryonic development.

Elevated serum levels of transforming growth factor-alpha in breast cancer patients.

Previous studies suggest that transforming growth factor-alpha (TGF alpha) may have the potential of a tumor marker. Since the levels of serum TGF alpha in cancer patients and healthy individuals have not been reported, we determined the serum TGF alpha levels of 83 breast cancer patients and 74 healthy individuals by using a TGF alpha radioimmunoassay kit. All of the cancer patients' sera were positive for TGF alpha; their TGF alpha concentrations ranged from 210 to 740 pg/ml, with a mean of 353 +/- 98 pg/ml. Sixty-seven percent (50 cases) of normal sera were positive for TGF alpha; the levels ranged from 120 to 207 pg/ml, with a mean of 144 +/- 17 pg/ml. The difference in serum TGF alpha levels between cancer patients of different disease stages and healthy individuals was found to be statistically significant by Student t-test and the Mann-Whitney test. No correlation was found between serum carcinoembryonic antigen and TGF alpha levels. The potential of serum immunoreactive TGF alpha as a marker for breast cancer warrants further investigation.

Expression of transforming growth factor alpha, amphiregulin and cripto-1 in human breast carcinomas.

The expression of three epidermal growth factor (EGF)-related peptides, transforming growth factor alpha (TGF-alpha), amphiregulin (AR) and cripto-1 (CR-1), was examined by immunocytochemistry (ICC) in 68 primary infiltrating ductal (IDCs) and infiltrating lobular breast carcinomas (ILCs), and in 23 adjacent non-involved human mammary tissue samples. Within the 68 IDC and ILC specimens, 54 (79%) expressed immunoreactive TGF-alpha, 52 (77%) expressed AR and 56 (82%) expressed CR-1. Cytoplasmic staining was observed with all of the antibodies, and this staining could be eliminated by preabsorption of the antibodies with the appropriate peptide immunogen. Cytoplasmic staining with all of the antibodies was confined to the carcinoma cells, since no specific immunoreactivity could be detected in the surrounding stromal or endothelial cells. In addition to cytoplasmic reactivity, the AR antibody also exhibited nuclear staining in a number of the carcinoma specimens. No significant correlations were found between the percentage of carcinoma cells that were positive for TGF-alpha, AR or CR-1 and oestrogen receptor status, axillary lymph node involvement, histological grade, tumour size, proliferative index, loss of heterozygosity on chromosome 17p or overall patient survival. However, a highly significant inverse correlation was observed between the average percentage of carcinoma cells that expressed AR in individual tumours and the presence of a point-mutated p53 gene. Likewise, a significantly higher percentage of tumour cells in the ILC group expressed AR as compared with the average percentage of tumour cells that expressed AR in the IDC group. Of the 23 adjacent, non-involved breast tissue samples, CR-1 could be detected by ICC in only three (13%), while TGF-alpha was found in six (26%) and AR in ten (43%) of the non-involved breast tissues. These data demonstrate that breast carcinomas express multiple EGF-related peptides and show that the differential expression of CR-1 in malignant breast epithelial cells may serve as a potential tumour marker for breast cancer.

Expression of the transforming growth factor‐α gene by human eosinophils is regulated by interleukin‐3, interleukin‐5, and granulocyte‐macrophage colony‐stimulating factor

Transforming growth factor (TGF)-alpha is a pleiotropic polypeptide which mediates a variety of tissue-specific cellular responses such as induction of proliferation, cell migration, vascularization, and formation of extracellular matrix. TGF-alpha is produced by certain tumor cells and embryogenic tissues, as well as by normal cells of different origin. Within the granulocytic lineage, TGF-alpha production has been shown in promyelocytic leukemia cells induced to differentiate, as well as in blood eosinophils of patients with the idiopathic hypereosinophilic syndrome. The present study was carried out in order to examine expression of the TGF-alpha gene in polymorphonuclear (PMN) and mononuclear (MN) blood cells of normal healthy donors. While MN and neutrophilic PMN failed to synthesize TGF-alpha transcripts and protein, eosinophils constitutively exhibited TGF-alpha transcripts accompanied by the release of immunoreactive TGF-alpha protein. Exposure of PMN and MN cells to the leukocyte-activating cytokines interleukin (IL)-3, IL-5, and granulocyte-macrophage colony-stimulating factor resulted in a several-fold increase of TGF-alpha mRNA expression and protein release by eosinophils, but not by neutrophils and MN cells. PMN and MN were insensitive to induction of TGF-alpha release by IL-8 and granulocyte colony-stimulating factor. These results point to a functional role of eosinophils in disorders characterized by unbalanced TGF-alpha production such as disease states associated with abnormal matrix formation and neovascularization which may be explained by the present demonstration of TGF-alpha production in these cells.

Expression of transforming growth factor alpha in human hepatocellular carcinoma

Transforming growth factor alpha (TGF-alpha) is a mitogenic polypeptide which acts on the epidermal growth factor receptor (EGFR). The aim of this study was to examine the expression of TGF-alpha in human hepatocellular carcinoma (HCC) and surrounding cirrhotic tissue, and to compare it with normal liver. Immunoreactive TGF-alpha was detected using two antibodies raised against its C terminus, a polyclonal antibody 26T and a monoclonal antibody Ab-2. In normal liver immunoreactive TGF-alpha was localised strongly to bile duct epithelium and weakly in occasional parenchymal cells but was notably absent from perisinusoidal and Kupffer cells. Eight out of twenty-eight (28%) cases of HCC expressed TGF-alpha as demonstrated by cytoplasmic staining with both antibodies and in four cases additional membrane immunoreactivity was demonstrated using 26T. However, where cirrhotic tissue surrounding TGF-alpha positive tumours was available for analysis immunoreactive TGF-alpha was detected in only 1/7 cases. TGF-alpha synthesis by malignant hepatocytes was supported by the detection of specific RNA by Northern blotting from two cases with TGF-alpha immunoreactivity. These results implicate bile duct epithelium as an important source of TGF-alpha in human liver. Furthermore, in HCC the expression of TGF-alpha in some cases, together with paucity of TGF-alpha immunoreactivity in surrounding cirrhotic tissue, suggests that TGF-alpha may play a role in continued cell proliferation in human hepatocarcinogenesis.

Intrahepatic distribution of transforming growth factor‐alpha (TGFα) during liver regeneration following carbon tetrachlorideinduced necrosis

The distribution of transforming growth factor-alpha (TGF alpha) in rat liver during regeneration was studied immunohistochemically using two antibodies, one a polyclonal (26T) raised against a synthetic peptide corresponding to the 17 C-terminal amino acids of the mature rat protein, and the other a monoclonal (Ab-2) raised against recombinant human protein. In normal liver, immunoreactive TGF alpha was detected in perivenular hepatocytes using both antibodies. No sinusoidal cells were found to contain the peptide. In response to carbon tetrachloride (CCI4)-induced necrosis, an initial increase in the intensity of immunoreactivity was noted at 24 h following exposure to the toxin. This coincided with the period immediately preceding the peak of hepatocyte proliferation; Ab-2 immunoreactive cells outnumbered 26T-positive cells. Thereafter there was a reduction in the number of TGF alpha-positive cells, but by day 4 the level of immunoreactivity had returned to that of normal liver. Using bromodeoxyuridine labelling, spatial and temporal relationships between TGF alpha expression and cell proliferation were identified, supporting the concept that this peptide plays an important role in the in vivo regenerative response to hepatic injury via an autocrine mechanism.

Immunohistochemical localization of transforming growth factor-alpha in human endometrium, decidua, and trophoblast.

Transforming growth factor-alpha (TGF-alpha) was localized immunohistochemically in human proliferative and secretory endometrium, decidua, and trophoblast from first, second, and third trimester pregnancies. In proliferative endometrium, TGF-alpha immunostaining was moderate to intense and localized predominantly to stromal cells, whereas glandular staining was absent to light. After ovulation, TGF-alpha staining was light within the stroma, but moderate to intense around spiral arterioles. Moderate to intense staining was also detected in glandular and surface epithelium in secretory endometrium, with no staining noted in subnuclear vacuoles. In hypersecretory endometrium, staining was predominantly epithelial. In decidua, TGF-alpha was detected in intermediate trophoblast and on the surface epithelium. In first trimester trophoblast, TGF-alpha was detected in both cytotrophoblast (CT) and syncytiotrophoblast. Cytoplasmic staining was light in CT and moderate to intense in ST, with particular staining of plasma membranes. Intense TGF-alpha staining of nuclear membranes in CT was noted. TGF-alpha staining was light to absent in second and absent in third trimester trophoblast. This study demonstrates immunoreactive TGF-alpha in tissues known to be responsive to epidermal growth factor, and also demonstrates the presence of immunoreactive TGF-alpha associated with nuclear membranes. Thus, TGF-alpha may play an autocrine/paracrine role in endometrial development and trophoblast function.

Transforming growth factor-alpha in human implantation trophoblast: immunohistochemical evidence for autocrine/paracrine function.

Epidermal growth factor (EGF) and its receptor (EGF-R) have been demonstrated in human implantation sites. Transforming growth factor-alpha (TGF-alpha), a protein with extensive sequence homology to EGF and with equal affinity for the EGF-R, was localized immunohistochemically in early intrauterine and ectopic pregnancies. Within the same experiments, TGF-alpha immunostaining was more intense in ectopic than intrauterine pregnancies. In both groups, TGF-alpha immunostaining was moderate to intense in the syncytiotrophoblast (ST), light to moderate in the cytotrophoblast (CT), and moderate to intense in intermediate trophoblast (IT). In ST, TGF-alpha immunostaining localized to the cytoplasm and plasma membranes, including microvilli. No nuclear associated TGF-alpha was noted in ST. In CT, differential TGF-alpha immunostaining was noted between the villous and nonvillous CT. Villous CT demonstrated light to absent cytoplasmic TGF-alpha immunostaining with intense nuclear staining. In contrast, nonvillous CT revealed moderate to intense cytoplasmic staining without demonstrable nuclear staining. These results demonstrate the presence of immunoreactive TGF-alpha in all forms of trophoblast. The known presence of the EGF-R suggests an autocrine/paracrine role for TGF-alpha during human implantation.

An immunocytochemical analysis of TGFα expression in benign and malignant prostatic tumors

Transforming growth factor alpha (TGF alpha) expression was analyzed immunocytochemically on formalin-fixed wax-embedded sections obtained from 24 benign prostatic hyperplasia (BPH) specimens and 76 prostatic carcinoma tissues, 3 human prostatic tumor xenografts, normal kidney, and salivary gland. Low amounts of TGF alpha immunopositivity were encountered in the epithelium of BPH glandular tissues, whereas in the prostatic adenocarcinoma samples, a greater heterogeneity and intensity of TGF alpha immunostaining was observed. The most intense staining was exhibited by the least differentiated tumors, although a few of these were weakly stained. Statistical analysis of the relationship of histopathological grade of tumor with TGF alpha expression in the carcinomas showed a significant correlation of these parameters, 0.01 > P > 0.001. The expression of the proliferation markers Ki-67 and PCNA was also analyzed in the carcinoma specimens, and the relationship of these to TGF alpha expression indicated that there was no significant correlation in this series of tumors between increased growth activity and TGF alpha expression (p approximately 0.25 with both markers). The prostatic carcinoma xenografts TEN12 and TEN15 contained low levels of immunoreactive TGF alpha, which was uniformly distributed, whilst heterogeneous immunostaining was observed in the uroepithelial xenograft TEN16. In the normal human kidney, TGF alpha was concentrated in the epithelium of the distal convoluted tubules (DCT) and the collecting tubules (CT), and lower amounts were identified in the proximal convoluted tubules (PCT). As in the prostatic carcinomas, the immunostaining was eliminated by prior absorption of the antibody with pure TGF alpha and not with human or mouse EGF. No crossreactivity of the TGF alpha antibody with salivary EGF was demonstrated. This study concludes that, in prostate carcinoma, the least differentiated tumors more often expressed greater amounts immunoreactive TGF alpha; however, no relationship between TGF alpha expression and cellular proliferation markers was found.

Transforming growth factor-alpha is a potential mediator of estrogen action in the mouse uterus.

To better understand the role of peptide growth factors in sex steroid hormone-mediated growth of the female reproductive tract, the effect of estrogen on the expression of transforming growth factor-alpha (TGF alpha) in mouse uterus was investigated. Our results show that estrogen induces the expression of TGF alpha mRNA in the mouse uterus in a dose- and time-dependent manner. The up-regulation of TGF alpha transcripts occurs predominantly in uterine epithelial cells. RIA and Western blot analysis demonstrate that immunoreactive TGF alpha protein is secreted at high levels into mouse uterine luminal fluid after estrogen treatment. The induction of uterine TGF alpha mRNA is specific to estrogen; nonestrogenic steroids did not induce expression. Antibody specific to TGF alpha significantly reduces estrogen-mediated uterine growth, which supports the concept that TGF alpha is a mitogen for the reproductive tract. Analysis of TGF alpha/EGF receptors by binding, affinity labeling, and phosphorylation studies indicates that functional receptors are present in the mouse uterus after estrogen exposure. Thus, our data support a physiological role for TGF alpha and its receptor pathway in the female mouse reproductive tract.

Transforming growth factor-alpha is a potential mediator of estrogen action in the mouse uterus

To better understand the role of peptide growth factors in sex steroid hormone-mediated growth of the female reproductive tract, the effect of estrogen on the expression of transforming growth factor-alpha (TGF alpha) in mouse uterus was investigated. Our results show that estrogen induces the expression of TGF alpha mRNA in the mouse uterus in a dose- and time-dependent manner. The up-regulation of TGF alpha transcripts occurs predominantly in uterine epithelial cells. RIA and Western blot analysis demonstrate that immunoreactive TGF alpha protein is secreted at high levels into mouse uterine luminal fluid after estrogen treatment. The induction of uterine TGF alpha mRNA is specific to estrogen; nonestrogenic steroids did not induce expression. Antibody specific to TGF alpha significantly reduces estrogen-mediated uterine growth, which supports the concept that TGF alpha is a mitogen for the reproductive tract. Analysis of TGF alpha/EGF receptors by binding, affinity labeling, and phosphorylation studies indicates that functional receptors are present in the mouse uterus after estrogen exposure. Thus, our data support a physiological role for TGF alpha and its receptor pathway in the female mouse reproductive tract.

Metanephric transforming growth factor-alpha is required for renal organogenesis in vitro.

The role of transforming growth factor-alpha (TGF-alpha) in metanephric development was examined. Metanephroi were removed from 13-day-old rat embryos and grown in organ culture for up to 6 days using serum-free chemically defined media. During this time the metanephroi increased in size and morphological complexity. Messenger RNA for TGF-alpha was present in the renal anlage. Immunoreactive TGF-alpha was produced by metanephroi in vitro and released into culture media. TGF-alpha of metanephric origin coeluted with recombinant human 125I-TGF-alpha after high-performance liquid chromatography of media. In contrast, epidermal growth factor was not detectable. Levels of TGF-alpha were relatively constant during 4 days in culture and averaged approximately 10(-10) M. Growth of the metanephric anlage, arborization of the ureteric bud, and tubulogenesis within the metanephric blastema were inhibited by the addition of anti-TGF-alpha antibodies to organ cultures. These data demonstrate production of TGF-alpha by developing rat metanephroi in organ culture. The peptide is necessary for growth and development in vitro. Our findings suggest a necessary role for TGF-alpha of metanephric origin as a promoter of renal organogenesis in vivo.

Transforming growth factor-alpha gene expression in late-gestation fetal rat lung.

Transforming growth factor-alpha (TGF-alpha) is a structural homologue of epidermal growth factor and competes for binding on a common transmembrane protein receptor/kinase. Although TGF-alpha appears to be more important than epidermal growth factor in embryogenesis and mammalian organogenesis, there is little information regarding its expression in developing lung. Accordingly, we measured levels of immunoreactive TGF-alpha and its gene expression in late-term fetal rat lung during the transition from the canalicular (19-20 d) to the saccular (21 d) stage. We report that at 19 d gestation intrapulmonary levels of TGF-alpha were 1.4 +/- 0.3 pmol/mg protein as determined by RIA, but had decreased by 50% at 21 d. To determine if the TGF-alpha gene is expressed in lung, RNA isolated from fetal rat lung was reverse transcribed, and a 302-bp fragment corresponding to a portion of the TGF-alpha gene was amplified by polymerase chain reaction. Southern blot hybridization with a 32P-labeled 2.3-kb EcoRI fragment of rat TGF-alpha cDNA clone showed a pattern of declining expression during late gestation. Therefore, fetal rat lung expresses TGF-alpha, as is evidenced by the synthesis of both the message and the protein. Because levels of protein were highest in the period of canalicular lung development when the respiratory acinus is formed and vascularized, a potential role for this intrapulmonary growth factor in pulmonary remodeling is suggested.