Increased Expression Of TGF-alpha Research Articles

Carbachol induces TGF-alpha expression and colonic epithelial cell proliferation in sensory-desensitised rats

Signals for the expression of the peptide growth factors epidermal growth factor and transforming growth factor-alpha (TGFalpha) in the gastrointestinal mucosa are largely unknown. We have shown earlier that extrinsic afferents in the gastrointestinal tract induce TGFalpha expression in colonic mucosa via the deliberation of neurotransmitters substance P and calcitonin gene-related peptide. The aim of our present study was to determine the effects of carbachol on mucosal TGFalpha expression and epithelial cell proliferation in vivo. Rats were divided in three groups. Group 1 was treated with vehicle only, group 2 received one single subcutaneous injection of 250 microg/kg of carbachol and animals in group 3 were sensory-desensitised prior to the injection of 250 microg/kg carbachol. TGFalpha expression and epithelial cell proliferation was evaluated by polymerase chain reaction, Western blot analysis and bromodeoxyuridine staining. Carbachol induced a significant increase in mucosal epithelial cell proliferation and TGFalpha expression. Sensory desensitisation did neither abolish the increased TGFalpha expression nor the increase in epithelial cell proliferation. Parasympathetic pathways are involved in the control of TGFalpha expression in gastrointestinal mucosa as well as in epithelial cell proliferation.

A novel inhibitor of tumor necrosis factor-α converting enzyme ameliorates polycystic kidney disease

Transforming growth factor-alpha (TGF-alpha) expression is abnormal in polycystic kidney disease. We previously demonstrated that blockade of the epidermal growth factor receptor (EGFR), the receptor for TGF-alpha, significantly slowed disease progression in the bpk murine model of autosomal-recessive kidney disease (ARPKD). In the present study, kidney TGF-alpha expression in this model is characterized, and the therapeutic potential of inhibiting TGF-alpha in ARPKD is examined using a novel inhibitor of tumor necrosis factor-alpha converting enzyme (TACE), the metalloproteinase that cleaves membrane-bound TGF-alpha to release the secreted ligand. Immunohistochemistry (IH) and Western analysis were performed on kidneys from cystic bpk mice and noncystic littermates at postnatal days 7, 14, and 21. Bpk mice and normal controls were treated with WTACE2, a competitive inhibitor of TACE, from day 7 until day 21, and the effects on kidney histology and renal function were assessed. Increased TGF-alpha expression by IH was demonstrated in the proximal tubules (PT) at postnatal day 7 and collecting tubules (CT) by day 21. A parallel increase in kidney TGF-alpha expression was demonstrated by Western analysis. Treatment of cystic bpk mice with WTACE2 resulted in a 43% reduction in kidney weight to body weight ratio (11.2 vs. 19.7%), improved cystic index (3.2 vs. 4.8), reduced cystic CT to PT ratio (1.2 vs. 8), and a greater than 30% reduction in BUN and serum creatinine. These findings support the pathophysiological role of the TGF-alpha/EGFR axis in murine ARPKD and demonstrate that inhibition of TGF-alpha secretion has therapeutic potential in PKD.

Transforming growth factor alpha immunoreactivity in human gallbladder and extrahepatic biliary tract tumours

Transforming growth factor alpha (TGF-alpha), a protein structurally similar to epidermal growth factor (EGF), is implicated in the development of many human tumours. This study examines the expression of TGF-alpha in gallbladder and extrahepatic biliary tract tumours in which EGFR expression has been previously shown to be important. A monoclonal antibody to the TGF-alpha protein was used to investigate the immunohistochemical expression of TGF-alpha in carcinoma of the gallbladder (n = 13), common bile duct (CBD) (n = 6) and ampulla of Vater (n = 8). Tissues from cases of chronic cholecystitis (n = 11), gallbladder dysplasia (n = 3) and adenoma (n = 1), and ampullary carcinoma in situ (CIS) (n = 3) were used as non-malignant controls. These cases were previously studied for EGFR expression. TGF-alpha overexpression, defined as intense immunoreactivity in more than two-thirds of cells immunostained for TGF-alpha, was present in most gallbladder carcinomas (n = 10; 77%) but with no significant differences in expression between different tumour grades. None of the cases of gallbladder dysplasia or chronic cholecystitis had strong TGF-alpha expression and this was significantly different from the carcinomas (P = 0.013 and P = 0.0001, respectively; chi 2 test), although a few cases of chronic cholecystitis showed weak (n = 4), moderate (n = 6) or no (n = 1) immunoreactivity. A few ampullary carcinomas (n = 2; 25%) and CIS (n = 1; 33%), and half of the CBD carcinomas (50%) had strong TGF-alpha immunoreactivity. There was correlation between TGF-alpha and EGFR immunoreactivity in the tumour cases (r = 0.70, r2 = 0.49, P = 0.0001; simple regression analysis), although the rate of EGFR immunoreactivity in CBD and ampullary carcinomas was somewhat higher than that of TGF-alpha. However, no statistically significant correlation between TGF-alpha expression with patient survival or tumour recurrence (r = 0.11, r2 = 0.012, P = 0.65; simple regression analysis) was found. Increased TGF-alpha expression occurs more frequently in gallbladder carcinoma than in gallbladder dysplasia, chronic cholecystitis, CBD or ampullary tumour, with no specific relationship to tumour grade, suggesting that TGF-alpha overexpression occurs early in the development of gallbladder cancers, and that biliary tract cancers have a different molecular origin. Correlation was found between TGF-alpha and EFGR expression in gallbladder and biliary tract tumours.

Expression of epidermal growth factor-related proteins and epidermal growth factor receptor in common epithelial ovarian tumors.

The biologic significance of epidermal growth factor (EGF)-related proteins and EGF receptor (EGFR) in the development and progression of human ovarian carcinoma was studied in 7 ovarian cystadenomas, 6 mucinous tumors of low malignant potential (LMP), and 25 invasive adenocarcinomas by immunohistochemistry. Results were correlated with clinicopathologic features. We also examined immunoreactivity in five serous adenocarcinomas both before and after cisplatin chemotherapy. Amphiregulin (AR) expression was observed only in mucinous tumors (4 of 8 cystadenomas, 2 of 6 tumors of LMP, and 6 of 10 cystadenocarcinomas), but was not detected in the serous tumors or clear cell adenocarcinomas. EGF, cripto, and EGFR expression was significantly higher in mucinous cystadenocarcinomas than in mucinous cystadenomas or mucinous tumors of LMP. Three of five specimens obtained at a second operation after chemotherapy had more intense or diffuse immunostaining for transforming growth factor alpha (TGF-alpha) than the initial specimens did. Coexpression of more than two of the EGF-related proteins or EGFR significantly correlated with increased surgical stage in serous and clear cell carcinoma. AR expression seems to correlate with mucinous differentiation rather than with advanced stages of ovarian tumors. Our results indicate that expression of some EGF-related proteins is greater in certain subtypes of ovarian carcinomas than in their benign counterparts and that coexpression of these proteins is associated with advanced stage in serous and clear cell carcinoma. Increased TGF-alpha expression may also be related to ovarian tumor resistance to cisplatin chemotherapy.

Growth markers in the human gastric mucosa during adaptation to continued aspirin administration.

The mechanism of gastric mucosal adaptation to continued aspirin (ASA) administration is unknown. We have investigated growth and proliferation markers in healthy subjects under prolonged ASA treatment. In eight healthy volunteers, ASA treatment (2 g/day) was continued for 14 days. Endoscopy was performed before medication; at days 3, 7, and 14 of ASA treatment; and at days 16 and 18 (2 and 4 days, respectively, after medication was ceased). Gastric biopsies from oxyntic and antral mucosa were studied by histology and by histochemistry for proliferating cell nuclear antigen (PCNA), epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), and epidermal growth factor receptor (EGFr). ASA treatment did not change the expression of EGF and EGFr significantly. The PCNA index showed local inconsistent variations. However, increased TGF-alpha expression after ASA was noted, particularly in hyperplastic surface epithelium. Edema and teleangiectases were common in gastric mucosa after ASA. An increasing incidence of foveolar hyperplasia was also noted in the antral mucosa. Healthy subjects on prolonged ASA treatment gradually develop parameters of chronic reactive gastritis accompanied by increased TGF-alpha expression in gastric surface epithelial cells, especially in hyperplastic areas.

Increased cell proliferation and transforming growth factor‐α (TGFα) in the gall‐bladder epithelium of patients with pancreaticobiliary maljunction

Pancreaticobiliary maljunction is associated frequently with gall-bladder carcinoma. Although increased turnover of the gall-bladder epithelium in patients with pancreaticobiliary maljunction is thought to predispose to carcinogenesis, there is little data to confirm this hypothesis. In addition, no previously published study has addressed the process underlying cell proliferation. In this study, cell kinetics were first evaluated using two methods, proliferating cell nuclear antigen (PCNA) immunohistochemical staining and argyrophilic nucleolar organizer region (AgNOR) staining. Second, immunohistochemistry was used to investigate the expression of transforming growth factor-alpha (TGF alpha), a potential regulator of cell proliferation in the gall-bladder. The gall-bladders of 11 patients with pancreaticobiliary maljunction were studied, and 11 gall-bladders removed from patients during other surgery were used as controls. The number of PCNA-positive cells and the number of AgNOR per nucleus were significantly greater in the gall-bladders of patients with pancreaticobiliary maljunction than in the control gall-bladders. The expression of TGF alpha was also significantly greater in the gallbladders of patients with pancreaticobiliary maljunction than in the control gall-bladders. In conclusion, these results suggest that the increased TGF alpha expression induced by pancreaticobiliary maljunction promotes proliferation of the gall-bladder epithelium, which may lead to carcinogenesis.

Adaptation of the gastric epithelium to injury is maintained in vitro and is associated with increased TGF-alpha expression.

Adaptation is the name given to the progressive decrease in gastric mucosal damage following repeated dosing with damaging agents. This study aimed to determine whether adaptation is an intrinsic property of the gastric epithelium and the role in the development of this process of TGF alpha. Rats were given either one or six daily doses of 10 mg/kg diclofenac or six daily doses of vehicle only (1% methylcellulose). On the 7th day, antral mucosa was taken for organ culture and loaded with [51Cr]. Explants were challenged with ethanol and damage quantified by [51Cr] release. In a separate experiment, rats were dosed as above and the gastric mucosa was extracted and TGF alpha quantified by RIA. The rate of [51Cr] release was significantly lower after ethanol injury in explants from rats previously adapted to diclofenac (9.2 +/- 2.5%) compared with those exposed to a single damaging dose of diclofenac (25.9 +/- 3.5%) or vehicle only (26.4 +/- 3.3%; P < 0.01; ANOVA). The concentration of TGF alpha was significantly higher in the gastric epithelium of rats adapted to diclofenac than other groups (P < 0.05; t-test). Cross adaptation of the gastric mucosa to injury has therefore been demonstrated in antral mucosal explants in organ culture while TGF alpha peptide expression is elevated in the adapted gastric mucosa. These findings suggest that adaptation is an inherent property of the gastric epithelium and it is likely that TGF alpha may play a role in its maintenance.

TGF ? expression in meningioma ? tumor progression and therapeutic response

Little is known of the molecular genetic mechanisms contributing to meningioma tumor progression. We evaluated a total of 26 clinical cases of meningioma: twenty three patients with meningioma treated at our institution between 1978 and 1990 and three asymptomatic cases found initially at autopsy. In addition, histologically normal meninges obtained at post-mortem examination from 5 cases were evaluated. There were 13 men and 10 women in the patient group with a median age of 48.7 years, treated by surgery and/or irradiation. Median follow-up was 46 months (range 16-152 months). Archival cases and age-matched normal meningeal tissue obtained at autopsy during the same time period were obtained for study. Patients with TGF alpha scores greater than 3.0 were more likely to fail treatment and had lower overall survival times than those with immunostaining scores of 1 or 2. Three autopsy cases where meningioma had been silent clinically had overall staining scores of 0.75, while 10 samples of normal meninges harvested from 5 cases at autopsy had staining scores of 0. Two patients each underwent 3 surgeries for recurrent tumor, serial specimens showed increased TGF alpha expression over time, though all material from these procedures was consistent with the diagnosis of histologically benign meningioma.

Association of transforming growth factor alpha (TGFA) and its precursors with malignant change in Barrett's epithelium: Biological and clinical variables

Adenocarcinomas of the gastro-esophageal junction (GEJ) and those arising in Barrett's esophagus (BE) are increasing in the West and have a poorer prognosis than distal stomach cancers. This has been attributed mainly to anatomical location, but biological factors such as growth-regulatory molecules have been implicated. We have investigated the expression of one of these factors, TGF alpha, and its precursor prepro TGF alpha in 82 adenocarcinomas of GEJ (32 resected specimens and 50 biopsies) as well as in 48 BE biopsies without tumor, by immunohistochemistry and by Western-blot analysis. TGF alpha staining was shown in the cytoplasm and membrane of cells. Western blot confirmed that most immunoreactivity was against mature TGF alpha (5.6 kDa), but higher-molecular-weight bands were also identifiable, suggesting some reactivity with prepro protein. TGF alpha expression was more extense and intense in intestinal metaplasia and cancer. The tubular histological type of adenocarcinoma was more often positive than the signet-ring type. Primary tumors with lymph-node metastases also had increased TGF alpha expression. We conclude, therefore, that there is differential regulation of the expression of TGF alpha and its precursors during esophageal tumorigenesis.

Expression of oestrogen receptor and transforming growth factor-alpha in MCF-7 cells after exposure to fractionated irradiation.

The expression of critical growth controlling genes was studied in MCF-7 cells after exposure to cumulative radiation doses of 20 and 60 Gy yielding cell lines called MCF-IR-1 and MCF-IR-3, respectively. The irradiated cell lines exhibited increased plating efficiencies but no differences in growth rates. MCF-IR-1/-IR-3 cells showed a reduced oestrogen responsiveness as indicated by their diminished response to tamoxifen-induced growth arrest and 17 beta-oestradiol (E2)-induced growth stimulation. The reduced expression of oestrogen receptor (ER) was determined by quantitative immune peroxidase staining of single cells and by total cellular E2 binding. There was also a radiation dose-dependent increase in the radiosensitivity of MCF-IR-3 cells as determined by the radiobiological parameters alpha, beta, and D (mean inactivation dose). Using RNA protection assays the irradiated cell lines produced steady-state ER mRNA at reduced levels while the levels of TGF-alpha were unchanged in MCF-IR-1 cells but increased 2.8-fold in MCF-IR-3 cells. A similar pattern was seen for TGF-alpha protein. While the current analyses cannot differentiate between radiation-induced altered gene expression or cell selection the results demonstrate that reduced ER expression and increased TGF-alpha expression are associated with the survival of MCF-7 cells after fractionated irradiation in vitro. In contrast, the MCF-IR cells were found to be more radiosensitive in acute survival experiments.

TGF-α Is Widely Expressed in Differentiated as well as Hyperproliferative Skin Epithelium

Transforming growth factor-alpha (TGF-alpha) is a potent mitogen for epithelial cells that is expressed at low levels in normal epidermis and overexpressed in psoriasis. Epidermal growth factor (EGF) has been shown to inhibit hair growth but stimulate the growth of sebaceous and sweat glands, suggesting a potential role for a member of the EGF/TGF-alpha family in the normal development and function of skin appendages as well as epidermis. The present work demonstrates TGF-alpha protein in eccrine ducts, and eccrine, sebaceous, and apocrine glands. The proliferative dermal hair bulb does not express TGF-alpha in contrast to the differentiated outer root sheath hair follicle epithelia. In addition, hyperproliferative skin diseases including bullous congenital ichthyosiform erythroderma, squamous cell carcinoma, and psoriasis show increased TGF-alpha expression. Thus, TGF-alpha may play a role in the morphogenesis and function of normal skin appendages and its overexpression is common in benign and malignant hyperproliferative skin diseases.

Immunologic Mechanisms in Psoriasis

The demonstration of activated T lymphocytes, HLA-DR+ I-CAM 1+, gamma IP-10+ keratinocytes, and increased levels of lymphokines in active plaques suggests that immunologic mechanisms may play a role in the pathogenesis of psoriasis. Epidermal hyperplasia and inflammation in psoriasis may be linked by those cytokines many of which are produced by both keratinocytes and leukocytes. Epidermal acanthosis and keratinocyte mitoses have been observed in delayed-type hypersensitivity reactions and after the intradermal injection of gamma interferon. Gamma interferon and its induced proteins have been demonstrated in active psoriatic plaques. Increased levels of the keratinocyte autocrine cytokines, transforming growth factor (TGF)-alpha and interleukin (IL)-6, have been detected in active plaques. The apparent overexpression of IL-6 in hyperplastic psoriatic tissue may explain features of psoriasis that link keratinocyte proliferation with immune activation and tissue inflammation. Both IL-6 and gamma interferon increased TGF-alpha expression in normal cultured keratinocytes. Cytokines produced during immune activation and other inflammatory processes may lead to epidermal hyperplasia.