Epidermal Growth Factor Receptor mRNA Expression Research Articles

Gene expression of growth factor receptors and neuronal markers in neuro blastoma cell lines

Gene expression of nerve growth factor receptor (NGFR), epidermal growth factor receptor (EGFR), chromogranin A (CGA) and neuropetide Y (NPY)in 4 neuroblastoma cell lines without N-myc amplification was studied by using Northern blot technique, N type cells expressed more NGFR mRNA than S type cells and have only little or no EGFR expression. S type cells had stronger expression of EGFR mRNA than that of N type cells accompanying with only less or even no NGFR expression. The results indicated that difference of gene expression of these growth factor receptors might be due to the various of tumor cell differetiation. Cells differentiating toward neurons gave more NGFR expression and cells prepared to be differentiating toward other direction might give more EGFR gene expression.

Tumor necrosis factor alpha induces the expression of transforming growth factor alpha and the epidermal growth factor receptor in human pancreatic cancer cells.

Recombinant human tumor necrosis factor (TNF)-alpha increased the expression of epidermal growth factor receptor (EGFR) mRNA and protein in all of six human pancreatic carcinoma cell lines tested. In addition, TNF-alpha increased the expression of an EGFR ligand, transforming growth factor (TGF)-alpha, at the mRNA and protein level in all cell lines. Increased expression of EGFR protein was associated with elevated steady-state EGFR mRNA levels. Nuclear run-on analysis showed that increase in EGFR mRNA was due to an increased rate of transcription. Induction of EGFR mRNA expression by TNF-alpha was abrogated by cycloheximide but occurred independently of TNF-alpha-induced production of TGF-alpha protein. Protein kinase A or Gi-type guanine nucleotide-binding proteins were not involved in this process as assessed by using appropriate stimulators and inhibitors of these signal transduction pathways. By contrast, staurosporine, an inhibitor of protein kinase C, partially inhibited, and 4-bromophenacyl bromide, a phospholipase inhibitor, completely inhibited TNF-alpha-dependent EGFR mRNA expression. The phospholipase C-specific inhibitor tricyclodecan-9-yl xanthogenate did not alter TNF-alpha-dependent EGFR mRNA expression, suggesting that phospholipase A2 is involved in the modulation of EGFR expression by TNF-alpha. The simultaneous induction of a ligand/receptor system by TNF-alpha suggests that this cytokine modulates autocrine growth-regulatory pathways in pancreatic cancer cells.

Expression of the epidermal growth factor receptor in human small cell lung cancer cell lines : Damstrup L, Rygaard K, Spang-Thomsen M, Poulsen HS. Department of Oncology, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen. Cancer Res 1992;52:308993

Epidermal growth factor (EGF) receptor expression was evaluated in a panel of 21 small cell lung cancer cell lines with radioreceptor assay, affinity labeling, and Northern blotting. We found high-affinity receptors to be expressed in 10 cell lines. Scatchard analysis of the binding data demonstrated that the cells bound between 3 and 52 fmol/mg protein with a KD ranging from 0.5 x 10(-10) to 2.7 x 10(-10) M. EGF binding to the receptor was confirmed by affinity-labeling EGF to the EGF receptor. The cross-linked complex had a M(r) of 170,000-180,000. Northern blotting showed the expression of EGF receptor mRNA in all 10 cell lines that were found to be EGF receptor-positive and in one cell line that was found to be EGF receptor-negative in the radioreceptor assay and affinity labeling. Our results provide, for the first time, evidence that a large proportion of a broad panel of small cell lung cancer cell lines express the EGF receptor.

Nucleotide sequence of the C-terminal region of the mouse epidermal growth factor receptor and expression in teratoma-derived cell lines with increased tumorigenic properties.

The isolation of a cDNA corresponding to a portion (amino acid 943 to 1073) of the cytoplasmic domain of the mouse EGF receptor surrounding the auto phosphorylation sites was obtained by using the reverse transcriptase polymerase chain reaction (RT-PCR) approach. Deduced amino acid sequence of mouse EGF receptor (EGFr) shows a 92% and 76% homology to corresponding regions in the human and the chicken EGFr, respectively. This cDNA was used to develop a sensitive RNase protection assay to investigate EGF receptor mRNA expression in mouse C3H teratoma derived cell lines with increased tumorigenic properties which display a progressive decrease of EGF binding and response. The results show that increased tumorigenicity was not accompanied by a change in EGF receptor mRNA expression. Moreover, they indicate that the RNase protection assay developed using the probe described here is a sensitive approach to investigate EGF receptor expression in murine cells.

Variation in cellular EGF receptor mRNA expression demonstrated by in situ reverse transcriptase polymerase chain reaction.

Cell to cell variation of epidermal growth factor (EGF) receptor mRNA levels in heterogeneous tissues has been demonstrated with an in situ assay that couples reverse transcriptase with the polymerase chain reaction (in situ RT-PCR). EGF receptor mRNA is consistently more highly expressed in regions where cell division occurs; EGF receptor mRNA is markedly reduced if not absent in areas of squamous cell differentiation. Both human and mouse tumors overexpress EGF receptor mRNA when compared to normal tissue. In situ RT-PCR performed on thin sections obtained from cell pellets of cultured cells with known levels of EGF receptor mRNA expression demonstrated that the mRNA detected is consistent with that observed by Northern analysis and quantitative PCR on isolated RNA and by protein levels detected by antibody binding assays. In situ RT-PCR is significantly more sensitive than in situ hybridization (ISH). The method avoids background associated with hybridization reactions as in ISH or ISH following in situ PCR. In situ RT-PCR appears to be applicable to any gene as long as the oligonucleotide primers used have been proven to be specific and effective in a standard RT-PCR assay.

The level of a transcription factor Sp1 is correlated with the expression of EGF receptor in human gastric carcinomas

The expression of the transcription factor Sp1 and EGF receptor (EGFR) was examined on human gastric carcinoma cell lines and gastric carcinoma tissues as well as corresponding normal mucosa in order to clarify the mechanism of overexpression of EGFR gene without gene amplification. All 7 carcinoma cell lines expressed Sp1 mRNA, the levels of which were closely correlated with the expression of EGFR mRNA except for one cell line. The gel retardation analysis revealed that the levels of Sp1 mRNA were parallel to its DNA binding activities. In 18 surgical cases, 12 tumors expressed Sp1 mRNA at higher levels than normal mucosa. The cases with overexpression of Sp1 showed the high level of EGFR mRNA. These results suggest that overexpression of Sp1 in tumor cells may induce overexpression of EGFR without gene amplification in human gastric carcinomas.

Increased EGF binding and EGFR mRNA expression in rat aorta with chronic administration of pressor angiotensin II.

This study examines the changes in the mRNA expression of epidermal growth factor (EGF), EGF receptor (EGFR), platelet derived growth factor (PDGF-B), and transforming growth factor beta (TGF-beta 1) before and after sustained pressor infusion of angiotensin II (Ang II) for 4 weeks. A threefold increase occurred in the levels of EGFR mRNA (17,240 +/- 827 vs 6403 +/- 1372 units, P less than 0.01) and TGF-beta 1 mRNA (1644 +/- 584 vs 475 +/- 30 units, P less than 0.01) only in the aorta and not in the heart and kidney tissues. This increase in both of the above mRNA transcripts highly correlated (r = 0.96 and 0.92, P less than 0.01) with the elevation of blood pressure. The specific binding of 125I-labeled EGF to aortic membranes also increased (11,429 +/- 728 vs 8630 +/- 420 cpm/mg protein, P less than 0.05) with a parallel increase in the protein tyrosine kinase activity of the membranes indicating that the enhanced EGFR mRNA expression resulted in increased activity of a functional receptor. No significant changes were observed in either EGF mRNA or PDGF-B mRNA levels. These findings suggest that EGFR and TGF-beta 1 participate in the long-term progressive pressor response to Ang II and thus potentially in the progression and the maintenance of chronic hypertension.

Spatiotemporal increases in epidermal growth factor receptors following peripheral nerve injury

Non-neuronal cells of peripheral nerve respond to axonal injury with a series of cellular changes that facilitate neuronal regeneration. To characterize the potential role of the epidermal growth factor (EGF) family of proteins in this response, we monitored the expression of EGF receptor mRNA and protein in the injured rat sciatic nerve. EGF receptor mRNA is synthesized in both primary cultured fibroblasts and Schwann cells, and Schwann cells express EGF receptor-like immunoreactivity. In situ hybridization and immunocytochemistry revealed that EGF receptor mRNA and protein are expressed in Schwann cells and fibroblasts of the sciatic nerve in vivo, and that receptor levels increase following nerve injury. Thirty-six hours postlesion, EGF receptors were expressed in gradients along the nerve both proximal and distal to the lesion, with the highest levels localized adjacent to the transection site. By 72 hr, receptor levels were maintained in a gradient in the proximal segment, but were uniformly increased throughout the portions of the distal segment that were analyzed. These changes were similar to those observed for low-affinity NGF receptor mRNA and protein, with transection causing increased expression in both Schwann cells and fibroblasts. Northern blots confirmed that primary cultured fibroblasts express low-affinity NGF receptor mRNA. To determine whether spatiotemporal gradients were a general characteristic of the nerve injury response, we monitored expression of the mRNA encoding the major myelin protein P0. Levels of P0 mRNA decreased initially in cells immediately adjacent to the transection site and, by 72 hr, were uniformly decreased throughout the distal segment. These data suggest that members of the EGF family of proteins may play a role in the peripheral nerve response to injury, and demonstrate a generalized gradient of cellular responses that commence at the transection site and progress distally in the nerve in the absence of intact axons.

Decreased response to epidermal growth factor during cellular senescence in cultured human microvascular endothelial cells

We have previously demonstrated that epidermal growth factor (EGF) induces cell migration, tissue-type plasminogen activator synthesis, as well as tubular formation in microvascular endothelial cells from human omental tissue. In this study, we compared the responsiveness to EGF of late passaged (senescent) human omental microvascular endothelial (HOME) cells with that of early passaged (young) HOME cells. We have employed HOME cells derived from surgically resected omental samples from 14 patients. EGF-stimulated cell migration significantly more in the young cells than in the senescent cells during serial cultivation (aging) in vitro. Scatchard analysis demonstrated that the number for both high and low affinity receptors for EGF in HOME cells was decreased dramatically during serial cultivation. The expression of EGF receptor mRNA was also decreased in the senescent HOME cells. Treatment of HOME cells with EGF significantly increased cellular mRNA levels of tissue-type plasminogen activator, and two protooncogenes, c-fos and c-myc, in young HOME cells, but not in senescent HOME cells. Thus HOME cells aged in vitro show a decreased responsiveness to EGF, resulting in decreased migration of human endothelial cells. The serial cultivation of human endothelial cells in vitro may downregulate EGF receptor and decrease responsiveness to exogenous EGF, a potent angiogenic factor.

Dexamethasone and retinoic acid regulate the expression of epidermal growth factor receptor mRNA by distinct mechanisms

Retinoic acid and dexamethasone have antagonistic effects on epidermal growth factor (EGF) receptor expression in fetal rat lung (FRL) cells: Receptor synthesis is enhanced by retinoic acid and reduced by dexamethasone. In the presence of actinomycin D, neither agent has the capacity to modify receptor synthesis or 125I-EGF binding capacity. Northern blot analysis demonstrates a tenfold increase in EGF mRNA following retinoic acid treatment and a 60% decrease in receptor message levels after dexamethasone treatment. To dissect the mechanisms of these effects, the expression of mRNA was separated from effects requiring protein synthesis by the use of cycloheximide and actinomycin D. Ligand binding, EGF receptor protein synthesis, and mRNA levels were measured in cultures of FRL cells that were incubated with retinoic acid or dexamethasone in the presence of cycloheximide, then washed and reincubated with fresh media containing actinomycin D, but not retinoic acid, dexamethasone, or cycloheximide. The results demonstrate that dexamethasone reduces the expression of EGF receptor mRNA in the absence of protein synthesis. In contrast, the mechanism by which retinoic acid increases the expression of EGF receptor mRNA requires protein synthesis. These data indicate that, in FRL cells, dexamethasone negatively regulates EGF receptor mRNA in a direct manner, while retinoic acid controls transcription of an intermediate protein, possibly a transcription factor, that subsequently increases transcription of receptor message.

Increased epidermal growth factor receptor gene expression by γ-interferon in a human breast carcinoma cell line

The interferons are a group of naturally occurring proteins that inhibit the growth of tumours in vivo and many transformed cell lines in vitro. The mechanisms of action of interferon, however, remain unclear. The IFN induced inhibition of growth of many epithelial cancer cell lines is associated with changes in Epidermal Growth Factor Receptor (EGFR) binding or expression. Therefore, we examined the effect of IFN treatment on the expression of EGFR in a human breast carcinoma cell line, MDA 468. We have found the IFN-gamma inhibited, in a dose dependent fashion, the growth of MDA 468 cells. IFN decreased cell surface binding of 125I-EGF to EGFR by changing receptor number rather than affinity. However, total cellular receptor protein, as measured by immunoprecipitation with monoclonal antibodies, was increased in IFN-treated cells. The half-life of the metabolically labelled receptor was unchanged by treatment with IFN. Increased amounts of EGFR mRNA were observed in MDA 468 cells treated with IFN-gamma for 3 days. The levels of mRNA increased with time in culture, reaching a peak of four times control values after 5 days of treatment. This effect was observable with as little as 10 U ml-1 of IFN-gamma. Treatment of the cells with Actinomycin D to inhibit new RNA synthesis suggested that the stability of EGFR mRNA was not enhanced in IFN-gamma treated cells. The increase in receptor mRNA induced by IFN was not inhibited by cycloheximide. These data suggest IFN-gamma can increase expression of EGFR mRNA and protein in MDA 468 cells. Increased expression of EGFR mRNA and protein by IFN-gamma is associated with inhibition of cell growth.

Re-investigation of Ontogenesis of Epidermal Growth Factor Receptor mRNA in the Liver of Rats: Quantitative Evaluation of Northern Blot Analysis.

Changes in the expression rate of epidermal growth factor receptor (EGFR) mRNA with age in the liver of rats were examined to assess the contribution of EGF to the proliferation of hepatocytes in younger animals. Northern blot analyses with a 32P-labeled probe derived from the extracellular domain of EGFR cDNA were evaluated quantitatively by normalizing the densitometric scanning data with the relative amounts of poly(A)+ RNA in the samples. The expression of EGFR mRNA was low during the early period and increased towards the adult level after 21 days of birth. In contrast, the rate of beta-actin mRNA expression was significantly higher immediately after birth and showed a tendency to decrease with time.

Modulation of EGF Receptor Expression by Differentiating Agents in Human Colon Carcinoma Cell Lines

The existence of an autocrine loop for self-stimulation of growth in malignant cells has been proposed for transforming growth factor-alpha (TGF alpha) and its receptor, the epidermal growth factor (EGF) receptor, in a variety of malignant cell types. Expression of both has been described in colon carcinoma. In order to investigate whether there is a correlation between TGF alpha and EGF receptor mRNA expression and differentiation, we studied the effects of differentiating agents on seven human colon carcinoma cell lines. All of the lines responded to the differentiating agents. In four of the seven lines there was increased EGF receptor mRNA two to five days after treatment with 2 mM sodium butyrate. In three of these lines TGF alpha mRNA and protein were also increased. In the one cell line treated with the differentiating agents DMF and DMSO, EGF receptor mRNA was also increased. [125I]-EGF binding to the cells was measured before and after treatment with butyrate. In two of three cell lines, increased EGF receptor mRNA was accompanied by a 2.4-fold increase in the number of binding sites per cell. In SW620 cells, no EGF receptor binding was detected before or after butyrate treatment. In the two cell lines in which butyrate increased EGF receptor binding, simultaneous treatment with EGF did not enhance growth. These data demonstrate increased expression of the TGF alpha/EGF receptor system after differentiation of colon carcinoma cell lines and suggest that their expression may be characteristic of a differentiated phenotype.

Patterns of mRNA for epidermal growth factor receptor and keratin B-2 in normal cervical epithelium and in cervical intraepithelial neoplasia

Patterns of epidermal growth factor receptor (EGFR) and keratin B-2 (KB2) mRNA localization were studied in samples of normal cervical squamous epithelium and in samples of cervical intraepithelial neoplasia (CIN). 35 S-Labeled EGFR and KB2 DNA probes were used for in situ hybridization on formalin-fixed tissue sections. Normal cervical squamous epithelium showed predominantly basal and parabasal expression of EGFR mRNA and suprabasal and midepithelial localization of KB2 mRNA. CIN lesions with moderate to severe dysplasia were generally characterized by continued expression of EGFR mRNA and decreased KB2 mRNA in midepithelial locations. Ratios of KB2 mRNA levels at the basal layer to KB2 mRNA levels at the midepithelial location were increased in moderate and severe dysplasia (CIN II and III) compared with normal epithelium ( P < .01). Ratios of EGFR mRNA levels at the midepithelial level to those of EGFR mRNA at the basal layer were increased in moderate to severe dysplasia compared with normal epithelium. These findings indicate a possible in vivo role of EGFR gene expression in normal and neoplastic proliferation and in prevention of differentiation of the cervical epithelium.

Effect of EGF Administration on EGF Receptor mRNA in hCG Producing Tumor.

In this study we examined the expression of EGF receptor mRNA after EGF administration in hCG producing tumor (choriocarcinoma). We transplanted the tissue of choriocarcinoma into female nude mice and investigated the effects of EGF on the growth of tumors, the binding activity of EGF receptor and the expression of EGF receptor mRNA in the tumor tissues. Two doses of EGF 5.0 micrograms, 50 micrograms and phosphate buffered saline as a control were injected subcutaneously every day for four weeks. Removed tumors were used for immunocytochemical studies and EGF receptor mRNA investigations. HCG and EGF receptors were detected immunocytochemically in the tumor. The low dose EGF employed stimulated the tumor growth while the high dose EGF inhibited the tumor growth compared with that of the control group. The binding activity of EGF receptor and the expression of EGF receptor mRNA also changed in accordance with the stimulation or inhibition of tumor growth. The growth of hCG producing tumor by EGF administration appeared to be dependent upon the binding activity of EGF receptor and the expression of EGF receptor mRNA.

Increase of Epidermal Growth Factor Receptor Expression Associated with a Lack of Antiproliferative Effect of IFN-&amp;beta; in Human Lung Cancer Nodules in Organotypic Culture

The possible relationship between the effects of alpha 2-, beta- and gamma-interferons (IFNs) on the growth of alveolar II pulmonary tumor cells (A549) maintained in tridimensional organotypic culture (nodules) and the modulation of epidermal growth factor receptor (EGF-R) expression was investigated. Treatment with rHu IFN-alpha 2 or IFN-gamma which results in the inhibition of the growth of A549 nodules had no effect on the binding of 125I-EGF to these cells. In contrast, treatment with rHu IFN-beta which exhibits no antiproliferative activity on A549 nodules resulted in a reproducible increase of the binding of 125I-EGF. Scatchard analysis of the EGF binding data indicated that a 48-hour exposure period resulted in an increase in the apparent number of cell surface EGF-R but did not significantly alter receptor affinity. Results from Northern blot analysis showed that the enhanced expression of EGF-R on the A549 nodule cells treated with IFN-beta correlates with an increase in mRNA for EGF-R. No modification of the EGF-R mRNA expression was observed in nodules treated with IFN-alpha 2 or IFN-gamma. In this model, our results suggest a relationship between resistance to antiproliferative effect of IFN-beta and modulation of EGF-R.

Modulation of transforming growth factor alpha-dependent expression of epidermal growth factor receptor gene by transforming growth factor beta, triiodothyronine, and retinoic acid.

We have investigated the actions of transforming growth factor (TGF) type alpha on epidermal growth factor (EGF) receptor mRNA expression in MDA-468 human mammary carcinoma cells in serum-free media. We found that exposure of MDA-468 cells to TGF alpha results in elevated levels of EGF receptor mRNA. This increase in mRNA accumulation showed time and dose dependence. Addition of TGF beta 1 enhanced the accumulation of EGF receptor mRNA induced by TGF alpha in a time- and dose-dependent manner. We also found that triiodothyronine at physiological concentrations exerts synergistic control on the action of TGF alpha alone, or in association with TGF beta 1, on EGF receptor mRNA expression. Similarly, retinoic acid treatment also enhanced in a time- and dose-dependent manner the TGF alpha-dependent response of EGF receptor mRNA and acted synergistically with TGF beta 1. The results described here suggest that optimum regulation of EGF receptor gene expression by TGF alpha is a complex process involving synergistic interactions with heterologous growth factors and hormones.

Epidermal Growth Factor Receptor Gene Expression in Normal Human Kidney and Renal Cell Carcinoma

The epidermal growth factor receptor (EGFr) is a transmembrane glycoprotein detected on many cells and tissues including neoplastic and normal kidney. EGFr binds the mitogenic polypeptide hormone epidermal growth factor (EGF) as well as EGF-related transforming growth factor-alpha (TGF-alpha). Increases in EGFr gene expression and protein production have been implicated in the development of the malignant phenotype for certain cancers. To determine if alterations in EGFr gene expression are present in human renal cell carcinoma, paired samples of normal and neoplastic renal tissue from ten patients with advanced renal cell carcinoma were analyzed for EGFr mRNA content by Northern blot hybridization. The EGFr gene was constitutively expressed in 90% of normal kidney samples. In seven out of nine evaluable patients, tumors expressed 1.7 to 8.4 times more EGFr mRNA than corresponding normal tissue. Two patients showed no elevation of tumor EGFr mRNA and one patient had no identifiable EGFr transcripts in either neoplastic or normal kidney. Expression of EGFr mRNA was also detected in three tumor-derived and two established renal cell carcinoma cell lines. EGFr transcripts were not found in tumor infiltrating lymphocytes (TIL). These findings suggest that overexpression of EGFr mRNA may be associated with malignant transformation in renal cell carcinomas. (J. Urol., 142: 1364–1368, 1989)