transforming-growth-factor-alpha and Hypertrophy

We have recently identified transforming growth factor alpha (TGFα) as a novel growth factor involved in the joint disease osteoarthritis. The role of TGFα in normal cartilage and bone physiology however, has not been well defined.. The objective of this study was to determine the role of TGFα in bone development through investigation of the Tgfa knockout mouse.. The gross skeletons as well as the cartilage growth plates of Tgfa knockout mice and their control littermates were examined during several developmental stages ranging from newborn to ten weeks old.. Knockout mice experienced skeletal growth retardation and expansion of the hypertrophic zone of the growth plate. These phenotypes were transient and spontaneously resolved by ten weeks of age. Tgfa knockout growth plates also had fewer osteoclasts along the cartilage/bone interface. Furthermore, knockout mice expressed less RUNX2, RANKL, and MMP13 mRNA in their cartilage growth plates than controls did.. Tgfa knockout mice experience a delay in bone development, specifically the conversion of hypertrophic cartilage to true bone. The persistence of the hypertrophic zone of the growth plate appears to be mediated by a decrease in MMP13 and RANKL expression in hypertrophic chondrocytes and a resulting reduction in osteoclast recruitment. Overall, TGFα appears to be an important growth factor regulating the conversion of cartilage to bone during the process of endochondral ossification.

Topics: Animals; Bone and Bones; Bone Development; Cartilage; Chondrocytes; Female; Hypertrophy; Male; Mice; Mice, Knockout; Organ Culture Techniques; Tibia; Transforming Growth Factor alpha

The objective was to ascertain fibroblast growth factor-2 (FGF2), epidermal growth factor (EGF), and transforming growth factor-alpha (TGFalpha) mRNA expression and testis morphology during accelerated testicular growth after hemicastration in the neonatal boar. On Day 10 after birth (Day 0), boars were assigned to control (n = 28), no treatment; hemicastrated (n = 28), left testis removed. The right testis in both groups (n = 7) was removed on Days 5, 10, 15, and 20. Expression of mRNA for FGF2, EGF, and TGFalpha was determined by qRT-PCR using TaqMan. Testicular morphology was determined on Day 15. On Day 10, hemicastrated boars had a greater (P = 0.01) testis weight (6.2 +/- 0.8 g; mean +/- SEM) than controls (4.3 +/- 0.4 g) and on Day 15 testis weight in hemicastrated boars (8.8 +/- 0.8 g) was twice (P < 0.01) that of control boars (4.2 +/- 0.3 g). Seminiferous tubule volume was approximately doubled in hemicastrated boars (P < 0.01) and was associated with an increase (P < 0.01) in Sertoli cell number. Interstitial compartment volume was greater (P < 0.01) in hemicastrated boars. Leydig cell numbers were similar (P = 0.14) but volume was greater (P < 0.01) for hemicastrates. There were no differences (P > 0.05) between control and hemicastrated boars in TGFalpha or FGF2 expression on Day 5 or Day 10, and EGF was not detected. It was concluded that upregulation of TGFalpha or FGF2 expression is not a pre-requisite for enhanced testicular growth and increased Sertoli cell proliferation that occurs subsequent to hemicastration in the neonatal boar.

Topics: Animals; Animals, Newborn; Base Sequence; Cell Proliferation; DNA Primers; Epidermal Growth Factor; Fibroblast Growth Factor 2; Gene Expression Regulation, Developmental; Hypertrophy; Leydig Cells; Male; Orchiectomy; Organ Size; RNA, Messenger; Sertoli Cells; Sus scrofa; Testis; Transforming Growth Factor alpha

A prominent pathological feature of murine autoimmune gastritis is a pronounced mucosal hypertrophy. Here, we examined factors that may be responsible for inducing this hypertrophy. Because gastrin is known to be both an inducer of gastric mucosal cell proliferation and is elevated in autoimmune gastritis, mice deficient in gastrin were thymectomised at day 3 and assessed for autoimmune gastritis. Gastrin-deficient mice showed all the characteristic features of murine autoimmune gastritis, including gastric unit hypertrophy due to hyperproliferation and accumulation of immature epithelial cells, decreases in the number of zymogenic and parietal cells, and autoantibodies to the gastric H+/K+-ATPase. Hence, gastrin is not required for either the establishment of chronic gastritis or development of the typical pathological features of this disease. We also examined mRNA levels of a number of gastric mucosal growth factors in RNA samples from mice with hypertrophic autoimmune gastritis. Members of the Reg family, RegIIIbeta and RegIIIgamma, were greatly elevated in mice with hypertrophic gastritis, whereas RegI and amphiregulin (an EGF receptor ligand) were more modestly and/or inconsistently induced. These data demonstrate that induction of gastric mitogenic factors, such as members of the Reg family, can be achieved in inflammatory situations by gastrin-independent pathways. Members of the Reg family, in particular RegIIIbeta and RegIIIgamma, are good candidates to be involved in inducing the mucosal hyperproliferation in autoimmune gastritis. These findings are likely to be of relevance to other gastric inflammatory conditions.

Topics: Amphiregulin; Animals; Autoantibodies; Autoimmune Diseases; Chronic Disease; EGF Family of Proteins; Epidermal Growth Factor; ErbB Receptors; Gastric Mucosa; Gastrins; Gastritis; Gene Expression; Glycoproteins; Growth Substances; H(+)-K(+)-Exchanging ATPase; Heparin-binding EGF-like Growth Factor; Hypertrophy; Intercellular Signaling Peptides and Proteins; Mice; Mice, Inbred BALB C; Mice, Mutant Strains; Proteins; RNA, Messenger; Transforming Growth Factor alpha

To determine the exact role of TGF-alpha in glial activation after traumatic brain injury, we investigated the astroglial and microglial responses after cortical stab wound injury in TGF-alpha overexpressing mice. Adult male B6D2-TgN (MMTVTGFA) 29RjC transgenic mice were used for the subjects. This transgenic line carries a TGF-alpha cDNA under the control of the dexamethasone-inducible MMTV promoter. Thus, exogenous administration of dexamethasone induces TGF-alpha overexpression. Male B6D2F1/J mice at the same age served as wild-type animals. After the cortical stab wound injury, expression of glial fibrillary acidic protein, CD-11b and interleukine-6 were investigated immunohistochemically. The results indicate that TGF-alpha might affect astrocytic hypertrophy without affecting microgliosis not only in the normal condition, but also in the pathological condition. Moreover, overexpression of TGF-alpha induced obvious expression of IL-6 around the lesion. This fact might indicate possible role of TGF-alpha in affecting neuronal function.

Topics: Animals; Astrocytes; Brain Injuries; CD11b Antigen; Gene Expression; Glial Fibrillary Acidic Protein; Hypertrophy; Interleukin-6; Male; Mice; Mice, Transgenic; Transforming Growth Factor alpha; Wounds, Stab

Hypergastrinemia occurs frequently in association with acid suppression and Helicobacter infection, but its role in the progression to gastric atrophy and gastric cancer has not been well defined.. The effects of hypergastrinemia, and possible synergy with Helicobacter felis infection, were investigated in insulin-gastrin (INS-GAS) transgenic mice.. INS-GAS mice initially showed mild hypergastrinemia, increased maximal gastric acid secretion, and increased parietal cell number but later progressed to decreased parietal cell number and hypochlorhydria. Development of gastric atrophy was associated with increased expression of growth factors, heparin-binding epidermal growth factor and transforming growth factor alpha. At 20 months of age, INS-GAS mice showed no evidence of increased enterochromaffin-like cell number, but instead exhibited gastric metaplasia, dysplasia, carcinoma in situ, and gastric cancer with vascular invasion. Invasive gastric carcinoma was observed in 6 of 8 INS-GAS mice that were >20 months old. Helicobacter felis infection of INS-GAS mice led to accelerated (< or = 8 mo) development of intramucosal carcinoma (85%), with submucosal invasion (54%) and intravascular invasion (46%; P < or = 0.05).. These findings support the unexpected conclusion that chronic hypergastrinemia in mice can synergize with Helicobacter infection and contribute to eventual parietal cell loss and progression to gastric cancer.

Topics: Animals; Cell Count; Epidermal Growth Factor; Epithelial Cells; Gastric Acid; Gastrins; Gastritis, Atrophic; Helicobacter Infections; Heparin; Heparin-binding EGF-like Growth Factor; Hyperplasia; Hypertrophy; Intercellular Signaling Peptides and Proteins; Metaplasia; Mice; Mice, Transgenic; Stomach Neoplasms; Transforming Growth Factor alpha

The pancreas harbors growth factors such as the epidermal growth factor (EGF) family. The physiological and pathophysiological roles of growth factors in normal pancreas remain unsettled. Human pancreatic cancer overexpresses the EGF receptor, and the ligands EGF and transforming growth factor alpha (TGF-alpha). The aim of the present experiments was to study the effect of TGF-alpha in a pancreatic cancer cell line and in normal mouse pancreas.. The LN-36 cell line, established from a pancreatic duct cell adenocarcinoma, was incubated with TGF-alpha or EGF. The effect of an EGF receptor-specific, tyrosine kinase inhibitor (tyrphostin B56) with or without growth factors was also studied. The cell number was measured with the XTT-colorimetric method. TGF-alpha, the tyrphostins A25, B48, and B56, were in separate experiments infused during 1 wk to normal female mice by subcutaneous (sc) minipumps.. The LN-36 cell line responded to TGF-alpha and EGF with increased cell number; +61% with 10(-10) M TGF-alpha and +34% with 10(-9) M EGF. Tyrphostin B56 at a concentration of 10(-5) M reduced the cell number by 76%, but when incubated together with growth factors the reduction was only 44% with TGF-alpha, and 39% with EGF. Infusion of TGF-alpha increased mouse pancreatic wet weight and protein content but was without effect on DNA synthesis, measured as incorporation of tritiated thymidine. Infusion of three different tyrphostins did not influence mice pancreas.. The results support the role of TGF-alpha to maintain growth of pancreatic cancer cells by the EGF receptor. Infusion of TGF-alpha induced hypertrophy in normal mouse pancreas.

Topics: Animals; Cell Count; Dose-Response Relationship, Drug; Epidermal Growth Factor; ErbB Receptors; Female; Humans; Hypertrophy; Mice; Pancreas; Pancreatic Neoplasms; Transforming Growth Factor alpha; Tumor Cells, Cultured; Tyrphostins

Phenobarbital (PB) is a non-genotoxic liver tumor promoter used extensively in initiation-promotion protocols. To determine the mode of PB action, double transgenic mice overexpressing both the c-myc and transforming growth factor (TGF)-alpha genes were treated with PB in the food for 10 weeks, from 3 weeks of age. After 3-4 weeks on PB a peak in liver mass was noted, which subsequently leveled off at a value approximately 30% above untreated animals. The mitotic index in mice given PB peaked at 1 week of treatment and was significantly elevated compared with untreated animals. No significant difference between treated and untreated animals was seen thereafter, although a trend of PB-associated mitotic suppression was noticeable. The apoptotic index also showed a trend of suppression compared with untreated animals, significant after prolonged PB administration. Dysplastic hepatocytes were more prominent in PB-treated mice than untreated animals, particularly pericentrally. Removal of PB from the diet at 4 weeks of treatment led to a dramatic increase in apoptosis. This accompanied a drop in the liver mass to the level of untreated controls by 10 days. Throughout the study, PB-treated animals showed markedly lower levels of TGF-beta1 ligand, coincident with an elevated level of the anti-apoptotic protein Bcl-2. On withdrawal of PB, the levels of all these proteins rapidly changed to mirror those seen in untreated mice. In all treatment groups, no change in the levels of epidermal growth factor receptor, TGF-beta receptors I and II or Bcl-xS/L were seen. We conclude from our data that PB stimulates liver growth in double transgenic c-myc/TGF-alpha mice by induction of liver hypertrophy and inhibition of apoptosis, brought about by both a decrease in signaling through the TGF-beta pathway and an increase in Bcl-2. The data support the hypothesis that PB promotes neoplastic development through a reduction in the incidence of cell death.

Topics: Animals; Apoptosis; bcl-X Protein; Carcinogens; Cell Division; Diet; Gene Expression Regulation; Genes, bcl-2; Genes, myc; Hypertrophy; Liver; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Transgenic; Organ Size; Phenobarbital; Proto-Oncogene Proteins c-bcl-2; Receptors, Growth Factor; Transforming Growth Factor alpha; Transforming Growth Factor beta

Infantile hypertrophic pyloric stenosis (IHPS) is characterized by hypertrophy of the pyloric muscle. The growth of smooth-muscle cells (SMCs) is regulated by several growth factors. Transforming growth factor-alpha (TGF-alpha) is a growth-regulatory peptide found in a wide range of embryonic and adult tissues. It has been recognized that TGF-alpha has growth-promoting effects in vascular and visceral SMCs. The aim of this study was to investigate whether TGF-alpha plays a role in the pyloric-muscle hypertrophy in IHPS. Full-thickness pyloric-muscle biopsy specimens were obtained at the time of pyloromyotomy from 10 IHPS patients (age range 24-76 days). Age-matched control material included 10 pyloric-muscle specimens taken at autopsy in patients without evidence of gastrointestinal disease. Indirect immunohistochemistry was performed using the ABC method with anti-TGF-alpha polyclonal antibody. In-situ hybridization was performed using a digoxigenin-labelled, TGF-alpha-specific oligonucleotide probe. There was a marked increase in TGF-alpha immunoreactivity and messenger RNA (mRNA) expression in SMCs in pyloric circular and longitudinal muscle in IHPS specimens compared to controls. The increased expression of TGF-alpha mRNA together with increased TGF-alpha immunoreactivity in IHPS suggests increased local synthesis of TGF-alpha by pyloric SMCs, causing pyloric-muscle hypertrophy.

Topics: Biopsy; Humans; Hypertrophy; Immunohistochemistry; Infant; Infant, Newborn; Muscle, Smooth; Pyloric Stenosis; RNA, Messenger; Transforming Growth Factor alpha

We studied the development of liver tumors in male transforming growth factor alpha (TGF-alpha) transgenic mice of the CD1 strain and examined the expression of the transgene by immunohistochemistry and in situ hybridization. Livers of 4-5-week-old transgenic mice contained areas of centribobular hypertrophy with low glucose-6-phosphatase activity. These areas progressively expanded, and hypertrophy and dysplasia became generalized in livers of mice at 10-12 months of age. The expression of the transgene, determined by either immunohistochemistry or in situ hybridization, was uneven in animals that were 10 weeks old or older. The positive hepatocytes formed patches with a predominant centrilobular distribution. We studied a total of 23 liver tumors (7 hepatocellular carcinomas and 16 adenomas) obtained from 11 mice at 13-15 months of age and from one 7-month-old animal which received zinc sulfate to induce the transgene. The carcinomas were well differentiated tumors, without glucose-6-phosphatase or gamma-glutamyltranspeptidase activity, that developed from the dysplastic parenchyma and occasionally within an adenoma. In all carcinomas and in 56% of the adenomas there was overexpression of the transgene in relationship to the surrounding tissue. The majority of the tumors that overexpressed TGF-alpha were alpha-fetoprotein positive, while alpha-fetoprotein staining was not detected in tumors (all adenomas) that did not show excessive transgene expression. We conclude that TGF-alpha functions as a promoter of liver carcinogenesis through its effect as an autocrine inducer of hepatocyte proliferation. Further, the data indicate that TGF-alpha overexpression may favor tumor progression.

Topics: Animals; Carcinoma, Hepatocellular; Gene Expression; Histocytochemistry; Hypertrophy; Liver; Liver Neoplasms, Experimental; Male; Mice; Mice, Transgenic; Nucleic Acid Hybridization; Transforming Growth Factor alpha

Transforming growth factor alpha (TGF alpha) is thought to participate in the normal and pathologic processes of numerous tissues, including the gastric mucosa. To explore its role in vivo, transgenic mice were generated overexpressing TGF alpha in the stomach. TGF alpha induced dramatic structural and functional lesions of the glandular stomach that were similar to Ménétrier's disease in humans. Transgenic mice developed severe adenomatous hyperplasia that resulted in a striking nodular thickening or hypertrophy of the gastric mucosa. Secretions obtained from affected stomachs contained no detectable gastric acid, suggesting that parietal cell function had been greatly impaired. These findings demonstrate that overproduction of TGF alpha can stimulate cellular proliferation, suppress acid secretion, and perturb organogenesis of the stomach of transgenic mice. Moreover, TGF alpha may contribute to the pathogenesis of related human hypertrophic gastropathies, such as Ménétrier's disease.

Topics: Animals; Gastric Mucosa; Gastritis, Hypertrophic; Hypertrophy; Mice; Mice, Transgenic; Transforming Growth Factor alpha