Epidermal Growth Factor mRNA Research Articles

Interleukin 1alpha and interleukin 6 promote the in vitro growth of both normal and neoplastic human cervical epithelial cells.

Interleukin 1alpha (IL-1alpha), Interleukin 6 (IL-6) and epidermal growth factor (EGF) were tested for their ability to regulate epithelial cervical cell cytokine production and secretion and to induce proliferation of human normal and neoplastic epithelial cervical cells. IL-1alpha, and IL-6 enhanced tumour and normal cell growth by 20-120%. The interleukins efficacy was similar to that of EGF for some cell lines but not for normal esocervical cells. The stimulatory effects of the interleukins were observed in both human papilloma virus (HPV)-infected and HPV-non-infected cervical cells. Normal cells constitutively expressed IL-1alpha, IL-6 and EGF mRNA. All cell lines except C33A expressed IL-1alpha mRNA. CaSki, C-4II and HT-3 expressed mRNA for IL-6. IL-1alpha induced or increased IL-6 mRNA levels in the Me-180 and HT-3 lines and in normal cervical cells. IL-6 induced: (1) the expression of its own mRNA only in Me-180 cells that constitutively lacked IL-6 mRNA; (2) the expression of IL-1alpha mRNA in C-33A and increased IL-1alpha mRNA level in the case of Me180 cells. Increased amounts of IL-6 mRNA were found in normal cells when treated with IL-1alpha. In spite of the pattern of mRNA expression, only HT-3 and normal cervical cells constitutively secreted IL-6, and only normal cells were able to produce IL-1alpha protein. A significant IL-1alpha-dependent increase of IL-6 secretion was found in Me-1 80, HT-3 and normal cells. IL-1alpha- and IL-6-driven cell proliferations were almost completely inhibited by the addition of neutralizing anti-IL-6 antibodies. Taken together, these data suggest that interleukins play a role in cervical carcinogenesis as autocrine and/or paracrine stimuli.

Epidermal growth factor and transforming growth factor alpha mRNA expression in human breast cancer biopsies; analysis in relation to estradiol, progesterone and EGF receptor content.

Among the peptide growth factors active in breast glandular cell proliferation epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) are thought to play a major role in tumour development. They operate through binding to and activation of a common membrane receptor, defined as EGF-R. Their production is modulated by hormones and local growth factors. After it was shown by previous investigation in this laboratory that EGF-R could be detected in 90% of the tumours, but was masked by endogenous ligand in 36% of them, the question was raised as to the level of the ligand's expression in tumour tissue biopsies. Therefore, we investigated the expression of EGF and TGF alpha mRNA in 146 breast cancer biopsies by slot blot analysis using specific 32P-labelled probes. The data were correlated with sex steroids and EGF receptor content. Our results showed that EGF and TGF alpha coexisted in all tumour samples, and that their level of mRNA expression was similar in half of the tumours. Northern blot and polymerase chain reaction (PCR) analysis validated these findings. A significant direct correlation was found between the level of TGF alpha/EGF mRNA expression and the ER/progesterone receptor (PGR) content. TGF alpha and EGF mRNA levels were significantly higher in ER+ (P = 0.0015 and P = 0.0001, respectively) and in PGR+ tumours (P < 0.005 and P = 0.0001) than in their negative counterparts. Moreover, TGF alpha mRNA expression negatively correlated with the number of EGF-R binding sites measured by the standard method (P = 0.02), and it was significantly related to the number of sites occupied by endogenous ligand. In conclusion, it was shown that TGF alpha and EGF mRNA were coexpressed in all the tumour biopsies tested and that their level was higher in the hormone receptor positive than in negative samples. The correlation between the presence of ER/PGR sites, high level of TGF alpha/EGF mRNA and EGF-R occupancy by endogenous ligand is in favour of ER mediated control of TGF alpha and EGF production.

Mitogenic and Metabolic Actions of Epidermal Growth Factor on Rat Articular Chondrocytes: Modulation by Fetal Calf Serum, Transforming Growth Factor-β, and Tyrphostin

The effects of human recombinant epidermal growth factor (EGF) on rat articular chondrocytes from humeral and femoral head cartilage of 21-day-old Wistar rats were analyzed. The cells were cultured under standard conditions as monolayers. Cell proliferation was studied by [3H]thymidine incorporation and determination of DNA content, proteoglycan synthesis by [35S]sulfate incorporation, and collagen synthesis by [3H]proline incorporation. The presence of specific receptors was confirmed by [125I]-EGF binding and that of EGF and EGF-receptor (EGF-R) mRNA by reverse transcription and the polymerase chain reaction. EGF (0.5–2.5 ng/ml) stimulated [3H]thymidine incorporation and increased DNA content of cultures. The effect was strongest when serum concentration was low (≤1%) and was lost at high (≥7.5%) serum concentrations. The EGF-induced effect on deoxynucleic acid synthesis was inhibited by transforming growth factor-β and tyrphostin, a tyrosine kinase inhibitor that blocks the phosphorylation of tyrosine residues on EGF-R. Cultured rat articular chondrocytes possess a single class of high-affinity binding sites (Kd0.18 nm). There were about 4.5 × 109binding sites per microgram of DNA or about 37,800 binding sites per cell with 8.3 pg DNA per cell. Cultured cells contained EGF mRNA and EGF-R mRNA. Incubation of cells with EGF for 24 h decreased the EGF mRNA transcripts and increased the EGF-R mRNA levels. These findings suggest that EGF probably takes part in the regulation of chondrocyte activity under normal and presumably pathological conditions.

Expression of Basic Fibroblast Growth Factor, Epidermal Growth Factor, and Their Receptors in Castrated and Testosterone Injected Rat Prostates.

To examine the role of basic fibroblast growth factor (bFGF), epidermal growth factor (EGF) and their receptors in androgeninduced cell growth in the rat prostate, we divided 36 male wistar rats into 3 groups, consisting of an uncastrated and nontestosterone injected (C) group, a castrated and non-testosterone injected (CA) group, and a castrated and testosterone injected (CT) group. Each group was divided again into 2 groups and sacrificed at 4 and 8 weeks after the treatment, respectively. Injection with testosterone propionate was done subcutaneously at 4 mg/kg for a week. The epithelial cells in CT prostates exhibited much higher proliferative cell nuclear antigen (PCNA) labelling index compared with those in C prostates, and the PCNA index of the stromal cells of both groups was similar. bFGF expression increased mainly in epithelial and stromal cells in CA group. bFGF mRNA level also increased in the 4 weeks CA group. FGFR expression increased in all kind of cells of CA group, in which total FGFR mRNA level was also high. EGF immunoreactivity was intense in the proliferating epithelial cells of CT group, and EGF mRNA was also detected in the same cells. Epithelial cells in CA group were positive for EGFR, but not in CT group. However, total EGFR mRNA level increased in CT group. Taken together, bFGF synthesized by epithelial and stromal cells may participate in fibrosis and angiogenesis in the castrated rat prostates. On the other hand, androgen may induce the prostatic epithelial cell proliferation through, at least in part, autocrine or paracrine mechanism of bFGF and EGF.

Expression of Epidermal Growth Factor and Transforming Growth Factor Alpha during Ulcer Healing: Time Sequence Study

Background: Growth factors such as epidermal growth factor (EGF) and transforming growth factor alpha (TGFα) have been shown to share common receptor (EGFR) and to accelerate ulcer healing due to stimulation of cell proliferation, but the time sequence of expression of EGF and TGFα during ulcer healing has not been investigated. In this study the rate of cell proliferation and the gastric secretion and gene expression of mRNA for EGF and TGFα were determined during ulcer healing. Methods: Gastric ulcers were induced in 150 Wistar rats by serosal application of 100% acetic acid (ulcer area, 14 mm). Some of these animals were also equipped with a gastric fistula for the assessment of gastric secretion during ulcer healing. The animals were killed 0, 2, 4, 6, or 8 days after ulcer induction, and the ulcer area was determined. The mucosal sections with gastric ulcer were immunostained for proliferating cell nuclear antigen (PCNA) and for immunoexpression of EGF, TGFα, and EGFR. The expression of mRNA EGF and mRNA TGFα was also determined in the ulcer margin by reverse transcriptase (RT) polymerase chain reaction (PCR) using specific primers. Results: Two, 4, 6, and 8 days after ulcer induction the gastric ulcer area was gradually reduced from the initial size (day 0) by 47%, 70%. 80%, and 87%. respectively, and this was accompanied by an increase in PCNA with its maximum on day 4. The gastric acid and pepsin secretion was significantly reduced by 75% and 79%, respectively, on day 2 after ulcer induction but then the secretion tended to return to normal value by day 8. The expression of EGF, TGFα, and EGFR was negligible on day 0 but increased significantly during the healing, reaching maximum on day 4. Expression of EGF mRNA was detected on days 2, 4, and 6, and that of TGFα mRNA on days 2, 4. 6. and 8 after ulcer induction, with the most intense signals for both transcripts observed on day 2. Conclusions: 1) The enhancement in cell proliferation during ulcer healing may be mediated by increased release of EGF and TGFα; 2) the expression of EGF and TGFα mRNA precedes the overexpression of these growth factors at the ulcer margin during ulcer healing; and 3) the overexpression of growth factors coincides with the inhibition of gastric secretion and increased blood flow at the ulcer margin, indicating that these factors affect gastric secretion and blood flow in the course of ulcer healing.

Effect of thyroid hormone on urinary excretion of epidermal growth factor.

Thyroid hormones were demonstrated to upregulate the synthesis of epidermal growth factor (EGF) mRNA and proEGF in the kidneys in vivo. This prospective study was performed to examine the extent of the hypothyroid state in modulating EGF excretion in the urine (U-EGF; n = 23). Patients with thyroid cancer were serially followed up from the euthyroid status, which was retained by thyroxine supplement after thyroidectomy, to the hypothyroidism in preparing for 131I whole body scanning. Paired thyroid function panel, including triiodothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), and U-EGF levels were measured on a weekly basis. Logarithmically transformed values of U-EGF were inversely correlated with TSH serum levels (p = 0.0000), but positively associated with T4 levels (p = 0.0005). No apparent correlation was observed with the T3 serum content, age and gender of the patients (p > 0.1, respectively). If the interval of measurement was taken into consideration, serum TSH was the most significant factor in association with U-EGF (p = 0.0003). Our data indicate that excretion of EGF in human urine depends substantially upon thyroid hormone support.

Amphiregulin and Nerve Growth Factor Expression Are Regulated by Barrier Status in Murine Epidermis

Disruption of the murine permeability barrier by solvents or tape stripping stimulates a homeostatic repair response that includes increased epidermal DNA synthesis. To identify potential mediators of the increase in DNA synthesis, we have measured epidermal levels of mRNAs encoding various growth factors after acute barrier disruption. In this study, mRNAs for amphiregulin and nerve growth factor were each shown to increase over controls at 30 min, reach peak levels of 12- to 30-fold at 1-2 h, and return to control levels by 6 h after tape stripping. A similar time course for the increase of amphiregulin and nerve growth factor mRNAs was observed after an unrelated form of barrier disruption, i.e., acetone treatment. Furthermore, artificial restoration of the barrier by Latex occlusion, immediately following barrier disruption by acetone treatment, inhibited the increase in epidermal amphiregulin and nerve growth factor mRNA levels, indicating that barrier status regulates the production of these growth factors. In contrast, mRNA levels of transforming growth factor-beta1, an inhibitory growth factor, were unchanged at early times and decreased by 53% (p < 0.02) 6 h after tape stripping, whereas mRNA levels of transforming growth factor-alpha remained unchanged at all times after acute barrier disruption. These results suggest that barrier disruption stimulates the expression of amphiregulin and nerve growth factor. Together, these regulators of keratinocyte growth and differentiation may be responsible for the increased proliferative response that is associated with barrier disruption.

Importance of nitric oxide and capsaicin-sensitive afferent nerves in healing of stress lesions induced by epidermal growth factor.

Epidermal growth factor (EGF) is a potent mitogen implicated in gastroprotection and ulcer healing, but its possible interaction with nitric oxide (NO) and sensory nerves on healing after acute gastric damage has not been assessed. We examined the effects of topical application of a small dose (0.5 mg/kg) of capsaicin to stimulate sensory nerves and a larger parenteral dose of capsaicin (125 mg/kg s.c.) to deactivate these neurons or the effect of systemic administration of NG-nitro-L-arginine methyl ester (L-NAME) (20 mg/kg i.v.) to suppress NO synthase on healing of gastric lesions induced by 3.5 h of water immersion and restraint stress (WRS) in rats without or with EGF administration. Rats were sacrificed at 0, 6, 12, or 24 h after WRS and the gastric blood flow (GBF) was measured by the H2 gas clearance technique. Exposure to WRS produced many gastric lesions, with a marked decrease in GBF, but at 12 h these lesions started to heal and the lesion number was reduced by 75% after 24 h. This was accompanied by progressive increase in the GBF and an increase in expression of EGF mRNA in gastric mucosa, as detected by RT-PCR. Pretreatment with L-NAME or functional ablation of sensory nerves by capsaicin significantly delayed the healing of WRS lesions and accompanying hyperemia. In contrast, pretreatment with EGF (100 micrograms/kg s.c.) or glyceryl trinitrate (10 mg/kg i.g.), a donor of NO, or stimulation of sensory nerves by topical capsaicin significantly enhanced the healing of these lesions and increased the GBF. The acceleration of the healing and accompanying hyperemia induced by EGF at 12 h after WRS were completely reversed in rats pretreated with L-NAME or in those with capsaicin denervation. Addition of L-arginine but not D-arginine to L-NAME restored the healing of stress lesions and gastric hyperemia induced by this peptide. Removal of salivary glands, which reduced luminal content of EGF and DNA synthesis by about fourfold compared to rats with intact glands, produced a significant delay in healing, and this was further aggravated by capsaicin denervation. We conclude that EGF, sensory nerves, and NO play an important role in the healing of gastric mucosa from lesions induced by stress and that sensory nerves and NO appear to interact with EGF in the mechanism of mucosal recovery from stress lesions.

Expression of epidermal growth factor, transforming growth factor-alpha and their receptor in the human oesophagus.

Increasing evidence indicates that epidermal growth factor and transforming growth factor-alpha are involved in the maintenance of oesophageal mucosal integrity. However, their cellular origin and the exact localization of their receptor in the oesophagus are still unclear. Therefore, we examined the expression of the two growth factors and their shared receptor in the normal human oesophagus at both mRNA and protein level, by immunohistochemistry, in situ hybridization and reverse transcription-polymerase chain reaction. In addition to being expressed in the proliferative compartment of the oesophageal epithelium, the receptor was found in a variety of cells, including smooth muscle cells, submucosal gland cells and the epithelium lining their ducts. Immunohistochemically, the pattern of distribution of epidermal growth factor paralleled that of its receptor. In situ hybridization demonstrated epidermal growth factor mRNA expression in the oesophageal epithelium and submucosal glands. Additionally, amplified transcripts of predicted size were detected by reverse transcription-polymerase chain reaction, thus confirming that authentic transcripts of the growth factor exist in the normal human oesophagus. Transforming growth factor-alpha mRNA and protein expression, while similar to that of epidermal growth factor, predominated in the more differentiated cell layers of the stratified squamous epithelium. These results demonstrate that the normal oesophagus can synthesize both growth factors. Moreover, the peculiar distribution of these peptides and the concomitant expression of their receptor in multiple cell types suggest that the two growth factors may exert diverse physiological functions in the oesophagus and participate in defence and reparative events following mucosal injury.

The cytosolic 47-kilodalton protein that binds to the 3' untranslated region of epidermal growth factor transcripts responds to orchiectomy in a tissue-specific fashion.

The submaxillary gland (SMG) of the male mouse is known to contain more epidermal growth factor (EGF) messenger RNA (mRNA) than that of the female. In contrast, the SMG of female mice contains more of a cytosolic 47-kDa RNA binding protein that binds to a unique 23-b sequence at the end of the 3' untranslated region (3' UTR) of EGF, which includes the canonical polyadenylation signal in an AU-rich region containing a potential mRNA destabilizing sequence. Testosterone treatment can change the activity of this 47-kDa protein within 1 day, which precedes the change produced in the level and in the polyadenylation of EGF mRNA in female mice. In the kidney, however, neither the 47-kDa protein nor the polyadenylation pattern changed after testosterone. We now report that 2 weeks following orchiectomy of Balb/c mice, mature EGF peptide immunoreactivity levels fall by 96% (P < 0.0002), and mRNA levels fall by 76% (P < 0.0001). Orchiectomy also enhances the RNA binding activities of the 47-kDa protein in SMG cytosol but not in the kidney: UV cross-linking to 3' UTR RNA is increased by 67% (P < 0.01) and shifting of the gel mobility of the RNA is increased by 47% (P < 0.05). The polyadenylation pattern of EGF transcripts also changes in SMG but not in kidney cytosol. After orchiectomy, the population of EGF transcripts in the SMG with short, heterogenous poly-A tails (<50 A's) decreases by 31% (P < 0.03), whereas transcripts with long poly-A tails of approximately 50, 70, 100, and 200 A's all increase and become more distinct, resembling the pattern found in the normal female. Thus, 2 weeks after orchiectomy, the responses in EGF expression, EGF mRNA polyadenylation, and the activities of the 47-kDa 3' UTR binding protein are the reciprocal of the responses produced by injecting female mice with testosterone for 5 days, providing further evidence that circulating androgens regulate EGF expression posttranscriptionally in a sexually dimorphic, tissue-specific fashion.

&lt;italic&gt;De novo&lt;/italic&gt; expression of transforming growth factor-α in parathyroid gland tissue of patients with primary or secondary uraemic hyperparathyroidism

The factors involved in abnormal parathyroid cell secretory function and growth in patients with primary and secondary hyperparathyroidism are still incompletely understood. We studied the expression of transforming growth factor-α (TGF-α), epidermal growth factor (EGF) and EGF receptor (EGF-R) at the gene message and the protein level in parathyroid tissue obtained from six patients with primary hyperparathyroidism, 15 patients with secondary uraemic hyperparathyroidism and five subjects with normal parathyroid tissue, using in situ hybridization and/or immunostaining technique. We found a consistent expression of TGF-α mRNA and protein in parathyroid endocrine cells of all six cases of primary parathyroid adenoma and in nearly all cases of secondary hyperplasia, in contrast to the absence of expression in normal parathyroid tissue. A marked expression of EGF-R mRNA and protein was also found in four of five tissue samples of primary parathyroid adenoma, in 13 of 15 tissue samples of secondary parathyroid hyperplasia and in most samples of normal parathyroid gland tissue. EGF mRNA and protein expression was undetectable in the majority of parathyroid tissue samples examined. Since TGF-α is known to bind to the EGF-R, the finding of an increased expression of TGF-α at the gene message and the protein level, together with a strong expression of EGF-R, in hyperplastic and adenomatous parathyroid glands suggests that this growth factor interacts with its receptor to promote parathyroid cell proliferation, perhaps by an autocrine mechanism.

De novo expression of transforming growth factor-alpha in parathyroid gland tissue of patients with primary or secondary uraemic hyperparathyroidism.

The factors involved in abnormal parathyroid cell secretory function and growth in patients with primary and secondary hyperparathyroidism are still incompletely understood. We studied the expression of transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF) and EGF receptor (EGF-R) at the gene message and the protein level in parathyroid tissue obtained from six patients with primary hyperparathyroidism, 15 patients with secondary uraemic hyperparathyroidism and five subjects with normal parathyroid tissue, using in situ hybridization and/or immunostaining technique. We found a consistent expression of TGF-alpha mRNA and protein in parathyroid endocrine cells of all six cases of primary parathyroid adenoma and in nearly all cases of secondary hyperplasia, in contrast to the absence of expression in normal parathyroid tissue. A marked expression of EGF-R mRNA and protein was also found in four of five tissue samples of primary parathyroid adenoma, in 13 of 15 tissue samples of secondary parathyroid hyperplasia and in most samples of normal parathyroid gland tissue. EGF mRNA and protein expression was undetectable in the majority of parathyroid tissue samples examined. Since TGF-alpha is known to bind to the EGF-R, the finding of an increased expression of TGF-alpha at the gene message and the protein level, together with a strong expression of EGF-R, in hyperplastic and adenomatous parathyroid glands suggests that this growth factor interacts with its receptor to promote parathyroid cell proliferation, perhaps by an autocrine mechanism.

Regional distribution of heparin-binding epidermal growth factor-like growth factor mRNA and protein in adult rat forebrain

Regional distribution of heparin-binding epidermal growth factor-like growth factor mRNA and protein in adult rat forebrain

Regional distribution of heparin-binding epidermal growth factor-like growth factor mRNA and protein in adult rat forebrain

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a recently described member of the EGF family that binds to the stimulates phosphorylation of the EGF receptor (EGFR). In this study, we examined the cellular localization of HB-EGF gene transcripts and protein in adult rat forebrain. In situ hybridization studies showed that neurons in various regions, including cortex, hippocampus, and deep structures, express HB-EGF mRNA. Positively labeled cells were also present in white matter, which suggests that both neurons and glia express HB-EGF mRNA. Immunohistochemical studies with an antibody specific to proHB-EGF, a transmembrane form of HB-EGF, demonstrated ubiquitous immunoreactivity in neurons and glial cells in white matter. In view of the wide expression of its cognitive receptor, EGFR, in central nervous system neurons, our results suggest that HB-EGF is an endogenous ligand for EGFR in the central nervous system and may play an important role in physiological conditions.

In vivo and in vitro effects of epidermal growth factor on its receptor gene expression in rat dental follicle cells

Epidermal growth factor receptor (EGFR) is known to be localized early postnatally in the follicle of rat mandibular molars and to decline later. Here, EGFR mRNA present early postnatally in the follicle was revealed by in situ hybridization and reverse transcription-polymerase chain reaction. Injections of epidermal growth factor (EGF) enhanced the expression of EGFR mRNA but not EGF mRNA through day 5 postnatally in the follicle. By day 7 postnatally, the amount of EGFR mRNA was dramatically reduced and EGF injection at that time or later did not enhance its expression. Cultured dental follicle cells were also shown to contain both EGFR mRNA and EGF mRNA, but only EGFR mRNA expression was enhanced after incubation of the cells with EGF. The EGFR mRNA was apparently translated, because the cultured cells could be immunostained for EGFR. This enhancement of EGFR mRNA in the dental follicle cells by EGF may be a necessary prelude to the mitogenic effect of EGF on the cultured cells because incubating the dental follicle cells in EGF over 6 days resulted in almost a doubling in their number as compared to controls. These results indicate that the tissue necessary for eruption to occur, the dental follicle, contains EGFR mRNA in the early postnatal days. In turn, this mRNA is enhanced by EGF, a molecule known to accelerate eruption if injected early postnatally. Whether or not the mitogenic effect of the EGF on the cultured dental follicle cells is a mechanistic factor that contributes to the subsequent tooth eruption is unknown.

Impaired estrogen action in the uterus of insulin-like growth factor binding protein-1 transgenic mice.

Insulin-like growth factor-I (IGF-I) has been implicated as autocrine/paracrine mediator of estrogen action in the rodent uterus. Here, we examined the effects of 17-beta estradiol (E2), epidermal growth factor (EGF), and IGF-I on DNA synthesis in the uterus of ovariectomized (ovex) transgenic mice (Tg), which overexpress rat insulin-like growth factor binding protein-1 (IGFBP-1). Litter size was significantly reduced in Tg mice compared with wild-type mice. Immunohistochemical studies localized the expression of the transgene to the luminal and glandular epithelium. In addition, rat IGFBP-1 immunoreactivity was present in luminal secretions. E2-induced uterine DNA synthesis as measured by methyl-3H thymidine incorporation, was significantly reduced in ovex Tg mice; 4.77 +/- 0.59 and 4.97 +/- 0.53 for Tg strains 57C and 277A, respectively, compared with 8.65 +/- 0.73 fmol/microgram of DNA for Wt mice. Similarly, uterine weight after three daily injections of E2 was reduced in Tg mice compared with Wt mice; 2.85 +/- 0.39 vs. 4.23 +/- 0.26 mg/g BW, P < 0.01. Semiquantitative RT-PCR assays were used to demonstrate changes in uterine IGF-I messenger RNA (mRNA) and EGF mRNA abundance after administration of E2. An approximately 3-fold increase in IGF-I mRNA abundance was seen 6 h after E2 in both Tg and Wt mice. Over the same time course, little change was seen in EGF mRNA levels, which were similar in Tg and Wt mice. After 3 days of E2 treatment, an increase in EGF mRNA was apparent in Wt mice but not in Tg mice. The uterine DNA response to both IGF-I and EGF was significantly attenuated in Tg mice compared with Wt mice. The data reported here together with previous reports of E2 regulation of IGF-I and IGFBP-1 expression in uterus support the hypothesis that the IGF-I is a mediator of estrogen action in the uterus. In addition attenuation of the EGF response in the uterine tissue of Tg mice suggests that this response is also mediated, in part, by IGF-I.

Impaired estrogen action in the uterus of insulin-like growth factor binding protein-1 transgenic mice

Insulin-like growth factor-I (IGF-I) has been implicated as autocrine/paracrine mediator of estrogen action in the rodent uterus. Here, we examined the effects of 17-beta estradiol (E2), epidermal growth factor (EGF), and IGF-I on DNA synthesis in the uterus of ovariectomized (ovex) transgenic mice (Tg), which overexpress rat insulin-like growth factor binding protein-1 (IGFBP-1). Litter size was significantly reduced in Tg mice compared with wild-type mice. Immunohistochemical studies localized the expression of the transgene to the luminal and glandular epithelium. In addition, rat IGFBP-1 immunoreactivity was present in luminal secretions. E2-induced uterine DNA synthesis as measured by methyl-3H thymidine incorporation, was significantly reduced in ovex Tg mice; 4.77 +/- 0.59 and 4.97 +/- 0.53 for Tg strains 57C and 277A, respectively, compared with 8.65 +/- 0.73 fmol/microgram of DNA for Wt mice. Similarly, uterine weight after three daily injections of E2 was reduced in Tg mice compared with Wt mice; 2.85 +/- 0.39 vs. 4.23 +/- 0.26 mg/g BW, P < 0.01. Semiquantitative RT-PCR assays were used to demonstrate changes in uterine IGF-I messenger RNA (mRNA) and EGF mRNA abundance after administration of E2. An approximately 3-fold increase in IGF-I mRNA abundance was seen 6 h after E2 in both Tg and Wt mice. Over the same time course, little change was seen in EGF mRNA levels, which were similar in Tg and Wt mice. After 3 days of E2 treatment, an increase in EGF mRNA was apparent in Wt mice but not in Tg mice. The uterine DNA response to both IGF-I and EGF was significantly attenuated in Tg mice compared with Wt mice. The data reported here together with previous reports of E2 regulation of IGF-I and IGFBP-1 expression in uterus support the hypothesis that the IGF-I is a mediator of estrogen action in the uterus. In addition attenuation of the EGF response in the uterine tissue of Tg mice suggests that this response is also mediated, in part, by IGF-I.

Expression and localization of epidermal growth factor, transforming growth factor-alpha, and localization of their common receptor in fetal human lung development.

Transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), and their common EGF receptor have been shown to be involved in cell proliferation and lung maturation. The aim of the study was to determine the site of production of TGF-alpha and EGF mRNA and the cellular distribution of TGF-alpha/EGF proteins and EGF receptor, in fetal human lung. By using in situ hybridization with 35S-labeled cDNA probes in frozen sections from eight lungs from fetuses ranging from 12 to 33 wk of gestation, TGF-alpha and EGF mRNA transcripts appeared to be confined to the mesenchymal cells and mainly found in the dense connective tissue along the pleura, bronchi, and large vessels, but undetected in bronchial epithelial cells. The streptavidin-biotin immunoperoxidase method, applied to paraffin-embedded specimens from 39 fetuses ranging from 10 to 41 wk, showed that TGF-alpha, EGF, and EGF receptor exhibited a similar cellular distribution during the whole period of gestation. They were detected in the undifferentiated cells of the airway surface epithelium, mesothelial cells, smooth muscle, and a few mesenchymal cells, as early as 10 wk. After 12 wk, the immunoreactivity was strong in the ciliated, secretory, and basal cells, and in growing glands along the large airways, but proved lower in the distal airways. After 24 wk, the immunoreactivity remained in the airway epithelium, but was mainly localized in the apical domain of ciliated cells, in alveolar cells, and in the serous cells of the glands. The presence of TGF-alpha, EGF, and EGF receptor during the whole period of fetal lung development suggests that these factors are not only mitogenic, but can also be involved in epithelial maturation, through paracrine secretion, as most TGF-alpha and EGF mRNA transcripts are expressed in mesenchymal cells.

Changes in gene expression of growth factors and their receptors during castration-induced involution and androgen-induced regrowth of rat prostates

To find candidates for the mediator of the growth-promoting action of androgen in rat prostates, the changes in the steady-state levels of mRNAs coding for several growth factors and their receptors were examined by Northern blot analysis during castration-induced involution, and subsequent regrowth induced by androgen in the ventral and dorsolateral lobes. The changes in the growth factor systems and a typical secretory protein in the ventral lobe were similar to, but more prominent than, those in the dorsolateral lobe, showing the higher androgen dependency of the ventral lobe. Among the growth factors and their receptors investigated, only epidermal growth factor (EGF) showed apparent positive androgen dependency: EGF mRNA content in the ventral lobe decreased to about 30% of the normal level within 24 hr after castration, and increased, attaining about 200-300% of the normal level 3-5 days after androgen administration to castrated rats. mRNAs coding for all other factors examined, i.e., transforming growth factor-alpha (TGF-alpha), EGF receptor, basic fibroblast growth factor (bFGF), keratinocyte growth factor (KGF), FGF receptor 1, TGF-beta1, TGF-beta type II receptor, hepatocyte growth factor (HGF), and c-MET/HGF receptor, increased after castration in greater or lesser degree, and after a brief pause or a decrease some of them increased again attaining a second peak 3-5 days after androgen replacement. The second increase was evident in TGF-alpha, EGF receptor, KGF, and c-MET mRNAs. These results indicate the possibility that multiple growth factor-receptor systems participate in the androgen-dependent regrowth of castrated rat prostates.

Changes in gene expression of growth factors and their receptors during castration‐induced involution and androgen‐induced regrowth of rat prostates

To find candidates for the mediator of the growth-promoting action of androgen in rat prostates, the changes in the steady-state levels of mRNAs coding for several growth factors and their receptors were examined by Northern blot analysis during castration-induced involution, and subsequent regrowth induced by androgen in the ventral and dorsolateral lobes. The changes in the growth factor systems and a typical secretory protein in the ventral lobe were similar to, but more prominent than, those in the dorsolateral lobe, showing the higher androgen dependency of the ventral lobe. Among the growth factors and their receptors investigated, only epidermal growth factor (EGF) showed apparent positive androgen dependency: EGF mRNA content in the ventral lobe decreased to about 30% of the normal level within 24 hr after castration, and increased, attaining about 200–300% of the normal level 3–5 days after androgen administration to castrated rats. mRNAs coding for all other factors examined, i.e., transforming growth factor-α (TGF-α), EGF receptor, basic fibroblast growth factor (bFGF), keratinocyte growth factor (KGF), FGF receptor 1, TGF-β1, TGF-β type II receptor, hepatocyte growth factor (HGF), and c-MET/HGF receptor, increased after castration in greater or lesser degree, and after a brief pause or a decrease some of them increased again attaining a second peak 3–5 days after androgen replacement. The second increase was evident in TGF-α, EGF receptor, KGF, and c-MET mRNAs. These results indicate the possibility that multiple growth factor-receptor systems participate in the androgen-dependent regrowth of castrated rat prostates. © 1996 Wiley-Liss, Inc.