TGF-α Expression Research Articles

Lack of interleukin 6 (IL-6) and transforming growth factor alpha (TGF-alpha) expression in chromophobe renal cell carcinomas.

We demonstrate the constitutive expression of interleukin 6 (IL-6), IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) in normal kidney cells, and in the majority of renal oncocytomas, papillary and non-papillary renal cell carcinomas (RCCs) by reverse transcriptase polymerase chain reaction (RT-PCR) technique. No expression of IL-6 and TGF-alpha and variable expression of GM-CSF, IL-8, EGF and EGFR was seen in chromophobe RCCs. The lack of expression of IL-6 and TGF-alpha might be correlated with the growth pattern, poor vascularity and low malignancy of chromophobe RCCs.

Expression of transforming growth factor-? in hepatoblastoma

BACKGROUND Transforming growth factor-α (TGF-α) is a potent stimulator of cell proliferation in the liver and in liver tumors; however, its significance and association with hepatocyte proliferation remains unclear. METHODS Expression of TGF-α and proliferation markers, such as proliferating cell nuclear antigen (PCNA) and cyclin A, were studied and correlated with each other in samples of tumor and surrounding liver tissue taken from nine patients with hepatoblastoma. An avidin-biotin-peroxidase immunohistochemical method was used for detection of TGF-α, PCNA, and cyclin A, and in situ hybridization was used to detect TGF-α mRNA. RESULTS Two types of tumor cells of epithelial origin were distinguished based on the expression of TGF-α protein and RNA. The more differentiated "fetal" phenotype had a high expression of TGF-α and correlated with a low expression of proliferation markers. The less differentiated "embryonal" phenotype had low TGF-α expression and high proliferation activity. CONCLUSIONS The expression of TGF-α is associated with a certain morphologic phenotype of tumor cells in hepatoblastoma; higher expression can be detected in more differentiated tumor cells. The negative correlation between the expression of TGF-α and proliferation markers suggests that the less differentiated embryonal cells do not depend on growth stimulation provided by TGF-α. Cancer 1998;83:690-697. © 1998 American Cancer Society.

AH receptor, ARNT, glucocorticoid receptor, EGF receptor, EGF, TGF alpha, TGF beta 1, TGF beta 2, and TGF beta 3 expression in human embryonic palate, and effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

Protein and mRNA for epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha), EGF receptor, transforming growth factor-beta 1 (TGF beta 1), TGF beta 2, TGF beta 3, glucocorticoid receptor (GR), the aryl hydrocarbon receptor (AhR), and the Ah receptor nuclear translocator (ARNT) were localized in gestational days (GD) 49-59 human embryonic secondary palates. The response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was determined for expression of these genes following palatal organ culture. Craniofacial tissues were shipped in medium from the Human Embryology Laboratory, University of Washington, Seattle, WA. Half of each specimen was cultured in control medium and half in medium containing TCDD at either 1 x 10(-8) or 1 x 10(-10) M. After fixation and paraffin-embedding, sections were examined either immunohistochemically or by in situ hybridization. Expression patterns were determined for each gene for the major stages of palatogenesis and in response to TCDD and compared to previously determined patterns of expression in the same developmental stages of palatogenesis for the mouse (GD49-59 in human palatogenesis corresponds to GD12-16 in the mouse). Human and mouse palates were dissimilar in particular spatiotemporal patterns of expression of these genes. Relative to patterns in mouse palatal development, human tissues demonstrated expression of EGF at early palatal stages, expression of EGF receptor and TGF alpha throughout fusion events, and uniform expression of TGF beta 3 in all epithelial regions without specifically higher levels in the medial cells. The responses to TCDD also differed in patterns of gene expression as well as in concentration required to induce hyperplasia of the medial epithelium. In summary, human palates expressed all of these regulatory genes, responses to TCDD were detected, and comparison between mouse and human palates revealed interspecies variation that may be a factor in each species' response to TCDD, as well as other teratogenic exposures.

TGF alpha is dispensable for skin tumorigenesis in Tg.AC mice.

Alterations in growth factor signaling pathways frequently accompany the development and maintenance of epithelial neoplasia. Transforming growth factor alpha (TGF alpha) and its epidermal growth factor receptor have been thought to play an especially important role in epithelial neoplasia. In this study, mice were derived genetically deficient (null) in functional TGF alpha expression and carrying the Tg.AC/v-Ha-ras transgene. The goals were to determine if (a) papillomagenesis was dependent on TGF alpha and (b) progression to malignancy was dependent on TGF alpha expression. Groups of male and female mice heterozygous or homozygous for the TGF alpha null allele and hemizygous for the Tg.AC transgene were treated twice weekly for 10 or 15 wk with doses of 12-O-tetradecanoylphorbol-13-acetate (TPA) known to produce papillomas in Tg.AC mice. Papillomas were readily induced in both male and female TGF alpha null mice. Malignant progression of papillomas was observed in all TGF alpha null treatment groups. Additionally, we examined the response of TGF alpha null mice to full thickness dorsal wounds, a stimulus known to promote papillomagenesis in Tg.AC mice. As in the TPA study, papillomas were induced in both male and female TGF alpha null mice. These studies indicate that TGF alpha is not required for the induction and maintenance of papillomas nor is it essential for the malignant conversion of papillomas in Tg.AC mice.

IL-4-Dependent Regulation of TGF-α and TGF-β1 Expression in Human Eosinophils

AbstractTGFs play important roles in wound healing and carcinogenesis. We have previously demonstrated that eosinophils infiltrating into different pathologic processes elaborate TGF-α and TGF-β1. Eosinophils infiltrating hamster cutaneous wounds were found to express TGFs sequentially. In this study, we examined the biologic mediators that may regulate the expression of TGF-α and -β1 by eosinophils. Eosinophils were isolated from the peripheral blood of healthy donors and cultured in the absence or presence of IL-3, IL-4, and IL-5. Cells were analyzed by in situ hybridization and immunohistochemistry. Supernatants from these cultures were assayed for secreted TGF-α and TGF-β1 using TGF-specific ELISAs. IL-3, IL-4, and IL-5 independently up-regulated TGF-β1 mRNA and product expression by eosinophils in all donors. Interestingly, TGF-α production by eosinophils was up-regulated by IL-3 and IL-5 but was down-regulated by IL-4. Consistent with the ability of IL-4 to regulate eosinophil responses, IL-4 signaling molecules are present in human eosinophils. The observation that IL-4 can differentially regulate the expression of TGF-α and TGF-β1 suggests that IL-4 may serve as a physiologic molecular switch of TGF expression by the infiltrating eosinophils in wound healing and carcinogenesis.

Regional expression of transforming growth factor-alpha in rat ventral prostate during postnatal development, after androgen ablation, and after androgen replacement.

The prostate is a highly heterogeneous organ, composed of different types of epithelial and stromal cells organized regionally along the ductal network. Although androgen-stimulated growth and maintenance of the prostate gland primarily involve epithelial cells, it is unclear whether all epithelial cells are androgen dependent. Moreover, the actions of androgens may not be direct; a number of polypeptide growth factors, including transforming growth factor-alpha (TGFalpha), are postulated to mediate androgen action in the rat prostate. In this investigation, using an immunohistochemical technique, we examined the cellular and regional expression of TGFalpha in the rat ventral prostate during postnatal development to adulthood. TGFalpha-immunopositive cells were located throughout the ductal epithelium from postnatal days 5-20. By day 45 and thereafter, regional variation in TGFalpha expression became apparent; epithelial cells in the proximal segment exhibited intense staining, whereas those in the distal segment exhibited negligible staining. These observations were coincident with increased serum testosterone concentrations at puberty. To understand the role of androgen in the expression of TGFalpha in the epithelial cells of the distal and proximal segments of the adult rat ventral prostate, androgen was withdrawn by castration, and testosterone subsequently was administered. Androgen receptor protein expression decreased after castration and reappeared after androgen replacement in both the distal and proximal segments. TGFalpha staining was negligible in epithelial cells of the distal segment of intact adult rats, became prominent by 7 days after castration, but then diminished after the administration of testosterone. Western blot analyses revealed the presence of a specific 30-kDa immunoreactive form of TGFalpha in rat ventral prostate, and its quantity reflected the staining intensities observed in the immunohistochemical studies. These results suggest that TGFalpha expression is negatively regulated by androgen in epithelial cells of the distal segment. In contrast, staining for TGFalpha in epithelial cells of the proximal segment did not change with castration or testosterone administration, suggesting that TGFalpha is not regulated by androgen in this region of the ventral prostate. In summary, TGFalpha expression is differentially regulated among epithelial cells localized in two different regions of the ventral prostate. We hypothesize that TGFalpha may function as a survival factor for epithelial cells which, as a consequence of its expression, become androgen independent and thus escape apoptotic cell death after androgen ablation.

Impact of the Expression of Epidermal Growth Factor, Transforming Growth Factor Alpha, and Epidermal Growth Factor Receptor on the Prognosis of Superficial Bladder Cancer

Objectives. To investigate the correlation of epidermal growth factor receptor (EGFR) expression and its ligands EGF and transforming growth factor-alpha (TGF-α) with disease outcome in a cohort of patients with superficial bladder cancer. Methods. Tumor samples of 21 patients with transitional cell carcinoma of the bladder were analyzed by immunohistochemistry for expression of EGFR, EGF, and TGF-α. Disease-related events were recorded during a routine clinical follow-up and analyzed for possible correlation with the expression status of the above-mentioned proteins. Results. All Stage pT1 transitional cell carcinomas expressed EGFR, and 10 of 21 (48%) tumors showed focal areas of strong EGF and/or TGF-α expression. Of these, 80% with EGF positivity (8 of 10) had recurrences, whereas only 9% of patients without EGF staining (1 of 11) did so. The same pattern was observed with TGF-α. A strong association was confirmed between EGF/TGF-α positivity and tumor recurrence ( P <0.005). We also found that EGF and TGF-α were expressed in stroma and/or around the vessels of tumor tissue in 48% and 38% of the tumors, respectively. No association was found between the recurrence rate/vascular invasion and the stromal/vascular wall expression of the growth factors. Conclusions. Expression of EGF and TGF-α is correlated with tumor recurrence. Also, there is the ability of vessel walls to express EGF and TGF-α in superficial bladder cancer. Further clarification of the impact of this expression on angioinvasion of tumor cells may be helpful in understanding the nature of local invasion and metastasis.

Expression of TGF-α, EGF and apoptosis in the gastric mucosa of patients with Helicobacter pylori infection

Expression of TGF-α, EGF and apoptosis in the gastric mucosa of patients with Helicobacter pylori infection

Helicobacter pylori-positive peptic ulcer patients do not adapt to aspirin

Background: Recent studies indicate that eradication of Helicobacter pylori might prevent peptic ulcer formation in patients treated with non-steroidal anti-inflammatory drugs (NSAIDs). On the other hand, gastric adaptation after repeated exposures to aspirin (ASA) is well documented but the influence of H. pylori on this process remains to be elucidated. Aim: To compare gastric damage and adaptation following repeated exposures to ASA in a group of patients with H. pylori infection, before and after eradication of the bacterium, and in H. pylori-negative controls. Methods: Eight healthy volunteers without H. pylori infection and eight patients with duodenal ulcer (DU) history and H. pylori infection before and after H. pylori eradication were given ASA 2 g/day for a period of 14 days. Mucosal damage was evaluated by endoscopy and histology of biopsy samples. Gastric microbleeding, DNA synthesis in the gastric mucosa and mucosal expression, as well as luminal content of transforming growth factor-α (TGFα) were determined on days 0, 3, 7 and 14 of the ASA course. Results: In all patients aspirin-induced gastric damage reached a maximum on day 3. In H. pylori-positive patients, this damage was maintained at a similar level up to day 14, whereas in H. pylori-negative controls and H. pylori-eradicated patients this damage significantly lessened on day 14 and was accompanied by elevated DNA synthesis as well as increased mucosal expression and luminal release of TGFα. Conclusions: H. pylori-positive DU patients do not adapt to continued administration of ASA but eradication of the bacterium restores adaptation. This phenomenon deserves further clinical evaluation.

Ki-67, p53, Bcl-2, TGF-α and EGF receptor expression in rectal carcinoid tumors

Ki-67, p53, Bcl-2, TGF-α and EGF receptor expression in rectal carcinoid tumors

Effect of Ovariectomy on Mammary Gland Expression of TGF.ALPHA. and EGFR mRNAs and its Relation to Mammary Gland Involution in Mice.

To understand the relationship between transforming growth factor α (TGFα) and mammary gland involution, changes in the growth of normal and preneoplastic mammary glands, the expression of TGFα and epidermal growth factor receptor (EGFR) mRNAs in the mammary gland, and serum prolactin (PRL) level were examined in 3-month-old virgin SHN mice 4 to 108 days after ovariectomy (OVX). The formation of normal end-buds and preneoplastic hyperplastic alveolar nodules was significantly reduced after 9 days of OVX, associated with the decreased serum PRL level. Both TGFα and EGFR mRNA expression in the mammary glands declined 18 days after OVX. Thereafter, TGFα mRNA tended to increase, while EGFR mRNA continued to decrease. These observations suggest that the decline of both estrogen and PRL play major roles in the mammary gland involution after OVX, and that the decline of EGFR, through which TGFα manifests its effects, play a secondary role in this process.

上咽頭癌の転移機序

The purpose of this study was to examine the role of angiogenesis and the expression of matrix metalloproteinase 9 (MMP9) on metastasis in primary nasopharyngeal carcinoma (NPC). Intratumoral microvessels were highlighted by immunohistochemical staining of endothelial cells for von Willebrand factor (vWF). The expression of angiogenetic factors, including basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and transforming growth factor-α (TGF-α) was also evaluated in NPC specimens, in addition to the expression of Epstein-Barr virus (EBV) encoded small RNAs. The expression of bFGF, VEGF, TGF-α and LMP-1 increased significantly with the grade of regional lymph node metastases. Multiple regression analysis showed that the expression of latent membrane protein-1 (LMP-1) was the most important factor that affects the microvessel counts in NP.Matrix metalloproteinases (MMPs) are frequently expressed in malignant tumor cells and are thought to play crucial roles in tumor invasion and metastasis. In this study, the expression of MMP9 was found to be increased in EBV-infected type III latency lymphoma cell lines. Type III cell lines express abundant LMP-1, the principal EBV oncoprotein, as well as the other latency proteins including the transcriptional factor EBV nuclear antigen 2 (EBNA2) which is also required for cell immortalization. Transection of an LMP-1 expression plasmid in the C33A cell line increased MMP9 expression, whereas overexpression of EBNA2 did not. Deletional and mutational analysis of the MMP9 promoter region was also carried out with chloramphenicol acetyltransf erase (CAT) assays. We found that binding sites for NF-κB, SP-1 and AP-1 also contributed to induction of the MMP9 promoter by the viral protein, LMP-1, mainly through the NF-κB and, to a lasser extent, the SP-1 and AP-1 sites. These results indicate that expression of MMP9 is induced by LMP-1. In conclusion, these observations suggest that LMP-1 plays a key role in metastasis in NPC.

Bladder acellular matrix graft in rats: Its neurophysiologic properties and mRNA expression of growth factors TGF‐α and TGF‐β

To assess the neurophysiologic properties and molecular mechanisms of the bladder acellular matrix graft (BAMG), we performed cystometric and neurophysiologic studies in male Sprague-Dawley rats (n = 46) at varying intervals. The animals were assigned to 3 groups: 1) normal, 2) partial cystectomy (>50%), and 3) partial cystectomy (>50%) and grafting with a BAMG of equal size. Additionally, matrix-grafted and host bladders were processed for analysis of mRNA expression of transforming growth factor (TGF)-α, TGF-β1, TGF-β2, and TGF-β3 by reverse transcriptase polymerase chain reaction. Matrix-grafted bladders showed a significantly higher bladder capacity at 3 and 6 weeks and 4 months than those with partial cystectomy alone, and a significantly higher bladder capacity at 4 months than in normal controls (P ≤ 0.01). Residual urine volume was significantly increased at 4 months. Electrostimulation of the pelvic nerve provoked generalized bladder contractions, a response that was reduced by atropine and hexamethonium. Variable induction of TGF-α, TGF-β1, TGF-β2, and TGF-β3 gene transcription was evident in the BAMG, with prominent mRNA expression of TGF-α and TGF-β1 6 months after surgery. These cystometric results and detrusor responses to stimulation provide further evidence that graft components do not interfere with host components. Matrix-grafted rat bladders generate, although not increased over time, adequate intravesical pressure responses to produce sustained voiding. Gene expression of different growth factors may be significant in understanding their role in the development and differentiation of the BAMG for partial bladder replacement. Neurourol. Urodynam. 17:37–54, 1998. © 1998 Wiley-Liss, Inc.

Regulation of transforming growth factor alpha expression in a growth factor-independent cell line.

Aberrant transcriptional regulation of transforming growth factor alpha (TGF alpha) appears to be an important contributor to the malignant phenotype and the growth factor independence with which malignancy is frequently associated. However, little is known about the molecular mechanisms responsible for dysregulation of TGF alpha expression in the malignant phenotype. In this paper, we report on TGF alpha promoter regulation in the highly malignant growth factor-independent cell line HCT116. The HCT116 cell line expresses TGF alpha and the epidermal growth factor receptor (EGFR) but is not growth inhibited by antibodies to EGFR or TGF alpha. However, constitutive expression of TGF alpha antisense RNA in the HCT116 cell line resulted in the isolation of clones with markedly reduced TGF alpha mRNA and which were dependent on exogenous growth factors for proliferation. We hypothesized that if TGF alpha autocrine activation is the major stimulator of TGF alpha expression in this cell line, TGF alpha promoter activity should be reduced in the antisense TGF alpha clones in the absence of exogenous growth factor. This was the case. Moreover, transcriptional activation of the TGF alpha promoter was restored in an antisense-TGF alpha-mRNA-expressing clone which had reverted to a growth factor-independent phenotype. Using this model system, we were able to identify a 25-bp element within the TGF alpha promoter which conferred TGF alpha autoregulation to the TGF alpha promoter in the HCT116 cell line. In the TGF alpha-antisense-RNA-expressing clones, this element was activated by exogenous EGF. This 25-bp sequence contained no consensus sequences of known transcription factors so that the TGF alpha or EGF regulatory element within this 25-bp sequence represents a unique element. Further characterization of this 25-bp DNA sequence by deletion analysis revealed that regulation of TGF alpha promoter activity by this sequence is complex, as both repressors and activators bind in this region, but the overall expression of the activators is pivotal in determining the level of response to EGF or TGF alpha stimulation. The specific nuclear proteins binding to this region are also regulated in an autocrine-TGF alpha-dependent fashion and by exogenous EGF in EGF-deprived TGF alpha antisense clone 33. This regulation is identical to that seen in the growth factor-dependent cell line FET, which requires exogenous EGF for optimal growth. Moreover, the time response of the stimulation of trans-acting factor binding by EGF suggests that the effect is directly due to growth factor and not mediated by changes in growth state. We conclude that this element appears to represent the major positive regulator of TGF alpha expression in the growth factor-independent HCT116 cell line and may represent the major site of transcriptional dysregulation of TGF alpha promoter activity in the growth factor-independent phenotype.

Transforming growth factors alpha and beta-1 are differentially expressed in the bovine mammary gland during mammogenesis, lactogenesis, galactopoiesis and involution

Abstract Anatomical change and the scale of metabolic and biosynthetic reprogramming of the mammary gland during the life cycle imply an enormous tissue remodeling in the adult mammal. Growth factors are involved in the local control of the gland. Our aim was to analyze expression of transforming growth factors alpha and beta-1 (TGFa, TGFb-1) during different stages of growth and function. Tissue was obtained after slaughter from non-pregnant control heifers, from pregnant heifers (mammogenesis) and from cows during lactogenesis, galactopoiesis and involution (day 21, non-pregnant). Additional samples were obtained after mammary biopsies during involution (days 3, 7, 21, non-pregnant) and during redevelopment of a pregnant, dry cow. Other samples were obtained from heifers after induced mammogenesis and lactogenesis, with and without additional prolactin inhibition. Total RNA was isolated from mammary tissue and analyzed by reverse transcription-polymerase chain reaction and ribonuclease protection assay. TGFb-1 mRNA levels were highest during involution, especially during early involution (days 3 and 7). Lowest levels were detected during lactogenesis and galactopoiesis, with intermediate levels in the gland of control heifers and pregnant heifers. Highest TGFa expression was detected in glands of control heifers and dry cows. TGFa expression decreased during pregnancy and reached very low levels during lactation. TGFa mRNA increased in biopsy samples during involution of non-pregnant animals and increased further in the redeveloping, dry gland of a cow 2 weeks before parturition. TGFa mRNA levels were higher after induced mammogenesis than after induced lactogenesis. TGFa mRNA expression increased further during prolactin inhibition. These data suggest that TGFa may be important for development and TGFb-1 mainly important for involution of the bovine mammary gland. (This work was supported by the German Research Fundation; Scha 257/13-1).

Differential expression and response of growth factors in different metastatic variants of human pulmonary giant cell carcinoma

The cell lines PGbE1 and PGLH7, which have high and low metastatic potential respectively, were two different variants isolated from human pulmonary giant cell carcinoma cell line PG. This study compared the expression and response of several growth factors TGFα, TGFβ, bFGF, IL-6, IL-8 and ANG in the two cell lines. By using RT-PCR analysis and [3H] thymidine incorporation assay, it was found that IL-6, TGFα and their receptors IL-6R and EGFR were expressed at higher level in PGbE1 cells than in PGLH7 cells, while no significant differences were found in the expression of ANG, bFGF, IL-8, IL-8R and TGFβ. Recombinant IL-6 and TGFα stimulated the proliferation of both cells, while TGFβ had dual effects. These results suggest that ANG, bFGF IL-6, IL-8 and TGFα, β may be involved in the proliferation of pulmonary giant cell carcinoma via autocrine mechanism, and IL-6 and TGFα may play an important role in the metastasis of tumor cells.

Increased expression of transforming growth factor α precursors in acute experimental colitis in rats

Background and aim—Epidermal growth factor (EGF) and transforming growth factor α (TGF-α), members of the EGF family of growth factors, protect rat gastric and colonic mucosa against injury. Having shown...

Quantitative relationship between transforming growth factor-alpha and hepatic focal phenotype and progression in female mouse liver.

Modulations in the positive hepatocyte growth factor, transforming growth factor-alpha (TGF-alpha) and its receptor epidermal growth factor receptor (EGFR), occur in rat and human liver tumors. The purpose of this study was to determine if TGF-alpha and EGFR are altered in basophilic and acidophilic preneoplastic and neoplastic liver lesions generated in DEN-initiated mice exposed to a variety of hepatocarcinogens. Female B6C3F1 mice were initiated with N-nitrosodiethylamine (DEN) and treated with hepatocarcinogenic concentrations of unleaded gasoline vapor (2,000 ppm), methyl tertiary butyl ether vapor (7,814 ppm), phenobarbital (500 ppm, diet), or chlordane (25 ppm, diet). Hepatic foci and tumors were identified and evaluated immunohistochemically with antibodies for TGF-alpha and EGFR. In all treatment groups, basophilic hepatic foci were negative for TGF-alpha immunoreactivity (554/564, 98%). In contrast, regardless of treatment, acidophilic hepatic foci were immunoreactive for TGF-alpha (107/108, 99%). There was no significant difference in mean hepatic labeling index as measured by the incorporation of 5-bromo-2'-deoxyuridine between foci immunoreactive and nonimmunoreactive for TGF-alpha. The incidence of immunoreactivity for TGF-alpha increased in hepatocellular tumors that were predominantly of the basophilic phenotype. Of basophilic hepatocellular adenomas, 16/81 (20%) were immunoreactive for TGF-alpha, while 17/29 (59%) of hepatocellular carcinomas stained positive for TGF-alpha. A similar increased incidence of EGFR immunoreactivity was found in basophilic hepatocellular adenomas (17/67, 25%) and carcinomas (19/28, 68%) relative to basophilic foci (11/367, 3%), suggesting an autocrine mechanism for the development of mouse liver tumors. The increased incidence of TGF-alpha immunoreactivity in basophilic liver tumors suggests that TGF-alpha is a marker of tumor progression in mouse liver. Furthermore, TGF-alpha modulations were dependent on phenotype rather than treatment, indicating inherent differences in the expression of TGF-alpha in basophilic and acidophilic hepatic lesions.

Prenatal ontogeny of the epidermal growth factor receptor and its ligand, transforming growth factor alpha, in the rat brain.

Transforming growth factor alpha (TGF alpha) interacts with the epidermal growth factor receptor (EGF-R) to produce its biological effects. TGF alpha induces the proliferation and differentiation of central nervous system (CNS) astrocytes and pluripotent stem cells, as well as the survival and differentiation of postmitotic CNS neurons. Both TGF alpha and EGF-R have been localized to the postnatal CNS. As the majority of CNS neuronal proliferation and migration occurs antenatally, we have examined the ontogeny of TGF alpha and EGF-R in the embryonic rat brain by in situ hybridization. EGF-R mRNA was expressed in the brain as early as embryonic day 11 (E11; the earliest age examined). It was initially detected in the midbrain, with subsequent expression first in multiple germinal zones, followed by expression in numerous cells throughout the brain. In many brain areas, EGF-R mRNA appeared in germinal centers during the later stages of neurogenesis and the early stages of gliogenesis. In the midbrain, the distribution of EGF-R mRNA overlapped extensively with that of tyrosine hydroxylase mRNA, suggesting that fetal dopaminergic neurons express EGF-R. Immunocytochemistry was used to demonstrate the presence of EGF-R-immunoreactive protein in brain areas that expressed EGF-R mRNA on E15 and E20. The expression of TGF alpha in many brain structures preceded that of EGF-R mRNA. TGF alpha mRNA was distributed throughout many non-germinal centers of the brain on E12 and later. Some brain areas, such as the external granule cell layer of the cerebellum, expressed EGF-R, but not TGF alpha mRNA. Northern blot analysis demonstrated that mRNA species for both TGF alpha and EGF-R were similar in embryos and adults. These data indicate that TGF alpha and EGF-R are positioned to have a role in the genesis, differentiation, migration, or survival of numerous cell populations in the embryonic brain.

Expression of transforming growth factor-beta and type IV collagen in early streptozotocin-induced diabetes.

The earliest manifestations of type I diabetic nephropathy include mesangial matrix expansion, basement membrane thickening, and renal hypertrophy. Transforming growth factor (TGF)-beta, a potent inducer of matrix protein synthesis, is a prime candidate to mediate the glomerular changes observed in diabetes. However, the temporal expression of TGF-beta and matrix proteins during the early stage of diabetic nephropathy has not been clearly defined. Using in situ hybridization and immunohistochemistry, we determined the expression of TGF-beta and type IV collagen mRNAs and proteins in glomeruli and interstitium of diabetic rats 3, 7, and 14 days after streptozotocin (STZ) administration. There was a marked increase in the expression of TGF-beta and alpha1(IV) procollagen mRNAs in glomerular and tubulointerstitial cells as early as 3 days after induction of diabetes, an effect that persisted for 14 days. A concomitant increase in TGF-beta and type IV collagen proteins was also observed at each time point. Insulin treatment substantially inhibited the increased expression of TGF-beta and collagen type IV mRNAs and proteins. We conclude that TGF-beta is increased in glomeruli during the early phase of rapid renal growth in diabetes. These findings suggest that TGF-beta may be a key factor involved in the pathogenesis of basement membrane thickening and extracellular matrix accumulation. Inhibition of TGF-beta and type IV collagen expression by insulin treatment suggests that they may be useful structural markers for determining the efficacy of therapeutic intervention during early diabetic nephropathy.