Progesterone receptor subunits are high-affinity substrates for phosphorylation by epidermal growth factor receptor.

Purified preparations of epidermal growth factor (EGF) receptor were used to test hen oviduct progesterone receptor subunits as substrates for phosphorylation catalyzed by EGF receptor. Both the 80-kilodalton (kDa) (A) and the 105-kDa (B) progesterone receptor subunits were phosphorylated in a reaction that required EGF and EGF receptor. No phosphorylation of progesterone receptor subunits was observed in the absence of EGF receptor, even when Ca2+ was substituted for Mg2+ and Mn2+. Phospho amino acid analysis revealed phosphorylation at tyrosine residues, with no phosphorylation detectable at serine or threonine residues. Two-dimensional maps of phosphopeptides generated from phosphorylated 80- or 105-kDa subunits by tryptic digestion revealed similar patterns, with resolution of two major, several minor, and a number of very minor phosphopeptides. The Km of progesterone receptor for phosphorylation by EGF-activated EGF receptor was 100 nM and the Vmax was 2.5 nmol/min per mg of EGF receptor protein at 0 degrees C. The stoichiometry of phosphorylation/hormone binding for progesterone receptor subunits was 0.31 at ice-bath temperature and approximately 1.0 at 22 degrees C.     

Metalloprotease-mediated ligand release regulates autocrine signaling through the epidermal growth factor receptor

Ligands that activate the epidermal growth factor receptor (EGFR) are synthesized as membrane-anchored precursors that appear to be proteolytically released by members of the ADAM family of metalloproteases. Because membrane-anchored EGFR ligands are thought to be biologically active, the role of ligand release in the regulation of EGFR signaling is unclear. To investigate this question, we used metalloprotease inhibitors to block EGFR ligand release from human mammary epithelial cells. These cells express both transforming growth factor alpha and amphiregulin and require autocrine signaling through the EGFR for proliferation and migration. We found that metalloprotease inhibitors reduced cell proliferation in direct proportion to their effect on transforming growth factor alpha release. Metalloprotease inhibitors also reduced growth of EGF-responsive tumorigenic cell lines and were synergistic with the inhibitory effects of antagonistic EGFR antibodies. Blocking release of EGFR ligands also strongly inhibited autocrine activation of the EGFR and reduced both the rate and persistence of cell migration. The effects of metalloprotease inhibitors could be reversed by either adding exogenous EGF or by expressing an artificial gene for EGF that lacked a membrane-anchoring domain. Our results indicate that soluble rather than membrane-anchored forms of the ligands mediate most of the biological effects of EGFR ligands. Metalloprotease inhibitors have shown promise in preventing spread of metastatic disease. Many of their antimetastatic effects could be the result of their ability to inhibit autocrine signaling through the EGFR.     

茶黄素和表皮生长因子受体对气道黏液分泌的影响

目的 探讨茶黄素对炎症反应时气道上皮细胞黏液分泌的影响.方法 通过人中性粒细胞弹性蛋白酶(HNE)刺激人肺腺癌细胞A549,构建炎症反应时气道黏液高分泌模型,以茶黄素和表皮生长因子受体(EGFR)阻断剂表皮生长因子受体阻断剂(AG1478)进行干预,观察黏蛋白5AC(MUCSAC)、EGFR、磷酸化EGFR(P-EGFR)、磷酸化细胞外信号调节激酶1/2(P-ERK1/2)、兔抗磷酸化p38(P-p38)及磷酸化JNK丝裂原活化蛋白激酶(P-JNK)的表达.用四甲基偶氮唑盐法测定细胞活性,再将A549细胞分为对照组、HNE处理组、茶黄素组、AG1478组和茶黄素+AG1478组.用逆转录PCR方法检测各组MUC5AC mRNA、EGFR mRNA的变化;Western blot法检测EGFR、P-EGFR、P-ERK1/2、P-p38和P-JNK蛋白的表达;酶联免疫吸附测定法观察MUCSAC蛋白表达的变化,并用细胞免疫激光共聚焦显微镜观察作用前后黏蛋白的分布.两样本均数间比较采用t检验,多样本均数间比较采用单因素方差分析.结果 HNE处理组MUC5AC的mRNA和蛋白的积分吸光度值分别为0.99±0.03和(169±6)μg/mg,EGFR mRNA和蛋白表达的积分吸光度值分别为0.98±0.02和(0.89±0.03)μg/mg,均较对照组[0.53±0.02、(105±4)μg/mg和0.61±0.11、0.21±0.05]明显升高;P-EGFR、P-ERK1/2的蛋白表达也较对照组显著增加,而P-p38的表达则有较低幅度的增强,P-JNK无明显变化.给予茶黄素及AG1478预处理后,与HNE刺激组相比,EGFR、P-EGFR、P-ERK1/2、P-p38均明显下调,P-JNK无相应改变;而茶黄素+AG1478组MUCSAC mRNA和MUC5AC的下调较单独用茶黄素或AG1478处理更为明显,其积分吸光度值分别为0.20±0.02和(125±3)μg/mg,差异均有统计学意义(t值分别为3.02和1405.94,均P<0.05).结论 茶黄素可通过下调EGFR水平、减少EGFR的活化、部分阻遏EGFR信号转导途径及细胞外信号调节激酶来实现对下游途径的影响,从而发挥茶黄素抑制炎性气道黏液高分泌形成的作用.     

Biosynthesis of the epidermal growth factor receptor in cultured human cells

A 160,000 mol wt precursor of the epidermal growth factor (EGF) receptor has been identified in human A-431 carcinoma cells and skin fibroblasts. The presence of one discrete precursor band indicates the presence of a slow processing step. We have determined that this slow processing step involves the conversion of high mannose N-linked oligosaccharides on the receptor precursor to primarily complex oligosaccharides on the mature form of the receptor. This is shown by 1) the presence of fucose, a characteristic terminal sugar of complex oligosaccharides, in only the mature receptor and by 2) the susceptibility of the precursor to digestion with endoglycosidase H, which cleaves high mannose N-linked oligosaccharides, but not complex oligosaccharides from glycoproteins. The precursor to mature receptor transition half-time is 1.7 h in A-431 cells. This long transition half-time causes an accumulation of approximately 7.2 X 10(5) precursor molecules per cell (approximately 12% of the total population of EGF receptors). The net quantity of mature EGF receptors, but not of receptor precursors, is reduced when EGF is added to the culture medium of A-431 cells. The presence of EGF in the growth medium also decreases electrophoretic migration (as a result of increased phosphate incorporation) of the mature receptor, but not that of the precursor. The EGF-insensitive state of the precursor is most likely due to its intracellular location.     

Diacylglycerol kinase delta regulates protein kinase C and epidermal growth factor receptor signaling

Diacylglycerol kinases (DGKs) phosphorylate diacylglycerol (DAG) to terminate its signaling. To study DGKdelta, we disrupted its gene in mice and found that DGKdelta deficiency reduced EGF receptor (EGFR) protein expression and activity. Similar to EGFR knockout mice, DGKdelta-deficient pups were born with open eyelids and died shortly after birth. PKCs are activated by DAG and phosphorylate EGFR to reduce its expression and activity. We found DAG accumulation, increased threonine phosphorylation of EGFR, enhanced phosphorylation of other PKC substrates, and increased PKC autophosphorylation in DGKdelta knockout cells, indicating that DGKdelta regulates EGFR by modulating PKC signaling.     

表皮生长因子及其受体在糜烂胃黏膜中的表达

目的:观察胃窦黏膜糜烂区与糜烂旁胃黏膜、慢性萎缩性胃炎中表皮生长因子(epidermal growth factor,EGF)及其受体(epidermal growth factor receptor,EGFR)的表达,探讨其在胃黏膜损伤修复中的意义.方法:选择经胃镜及病理确诊的慢性萎缩性胃炎伴胃窦黏膜糜烂患者50例,距糜烂区3cm处40例,无糜烂慢性萎缩性胃炎40例,采用免疫组织化学染色法测EGF及EGFR的表达.结果:胃窦黏膜糜烂区EGF、EGFR阳性表达率分别为40%和30%,明显高于糜烂旁胃黏膜15%和10%及无糜烂慢性萎缩性胃炎20%和12.5%的阳性表达率(P<0.05),有统计学意义,无糜烂慢性萎缩性胃炎组略高于糜烂旁胃黏膜组,但无统计学差异.结论:EGF、EGFR在胃黏膜损伤后高表达,对促进胃黏膜修复有着重要意义.     

Sphingosine 1-phosphate transactivates the platelet-derived growth factor beta receptor and epidermal growth factor receptor in vascular smooth muscle cells

Sphingosine 1-phosphate (S1P) is a bioactive lipid generated during vascular injury that regulates cell growth, differentiation, survival, and motility via endothelial differentiation gene (EDG) family G protein-coupled receptors. Although several G protein-coupled receptor ligands transactivate receptor tyrosine kinases, such as the epidermal growth factor receptor (EGFR), S1P-stimulated receptor tyrosine kinase transactivation has not been well studied. We show that platelet-derived growth factor beta receptor (PDGFbetaR) and EGFR are tyrosine phosphorylated in response to S1P in rat aortic vascular smooth muscle cells (VSMCs). S1P-stimulated transactivation of PDGFbetaR and EGFR was mediated via Gi-coupled EDG receptors. S1P-stimulated transactivation of EGFR and PDGFbetaR was dependent on Src, reactive oxygen species, and cholesterol-rich membranes. A phosphoinositide 3-kinase-Akt pathway was activated by S1P and blocked by AG1296 and AG1478. Activation of extracellular signal-regulated kinase (ERK) 1 and ERK2 pathway by S1P was blocked only by AG1478. In Chinese hamster ovary cells that expressed exogenous EDG-1, activation of Akt and ERK1/2 in response to S1P was observed and was enhanced by coexpression of PDGFbetaR or EGFR. S1P-mediated VSMC proliferation was shown to be secondary to transactivation, because it was suppressed by AG1296 and AG1478. These data establish S1P as an important stimulus for EGFR and PDGFbetaR activation in VSMCs that may have important implications for the vessel response to injury.     

Human epidermal growth factor receptor residue covalently cross-linked to epidermal growth factor.

An epidermal growth factor (EGF) receptor monoclonal antibody (mAb), mAb LA22, was used to analyze the covalent coupling of human EGF receptors to mouse EGF by the amine-reactive cross-linking agent disuccinimidyl suberate. A soluble Mr 105,000 truncated form of the receptor secreted by A-431 epidermoid carcinoma cells and consisting of the ligand-binding extracellular domain was cross-linked to 125I-labeled EGF. Digestion of this complex with an endoproteinase that specifically cleaves at the COOH side of glutamyl residue released a single radiolabeled glycosylated fragment of Mr 18,000 that reacted with mAb LA22. As the epitope for mAb LA22 resided between Ala-351 and Asp-364 of the mature receptor, this result localized the cross-linked receptor residue(s) to the 47-amino acid interval from Phe-321 to Glu-367. The receptor residue(s) involved in the covalent coupling of rat 125I-labeled transforming growth factor alpha was similarly localized to this region of the receptor. This receptor interval, which included two glycosylated asparaginyl residues at positions 328 and 337, contained but three amino acid residues that were potentially reactive with disuccinimidyl suberate: Lys-332, Lys-333, and Lys-336. Characterization of mAb LA22-reactive 125I-EGF-labeled receptor fragments generated by an endoproteinase specific for the COOH side of lysyl residue placed the NH2 termini of the two smallest fragments between the glycosylated residues Asn-328 and Asn-337. These results indicated that disuccinimidyl suberate cross-linked the NH2 group of EGF residue Asn-1 to the human EGF receptor residue Lys-336. Our results further suggest that EGF and transforming growth factor alpha, two members of the EGF family of peptide growth factors, interact with closely apposed or identical features of the receptor.     

Follicle-stimulating hormone regulates expression and activity of epidermal growth factor receptor in the murine ovarian follicle

Fertility depends on the precise coordination of multiple events within the ovarian follicle to ensure ovulation of a fertilizable egg. FSH promotes late follicular development, including expression of luteinizing hormone (LH) receptor by the granulosa cells. Expression of its receptor permits the subsequent LH surge to trigger the release of ligands that activate EGF receptors (EGFR) on the granulosa, thereby initiating the ovulatory events. Here we identify a previously unknown role for FSH in this signaling cascade. We show that follicles of Fshb^−/− mice, which cannot produce FSH, have a severely impaired ability to support two essential EGFR-regulated events: expansion of the cumulus granulosa cell layer that encloses the oocyte and meiotic maturation of the oocyte. These defects are not caused by an inability of Fshb^−/− oocytes to produce essential oocyte-secreted factors or of Fshb^−/− cumulus cells to respond. In contrast, although expression of both Egfr and EGFR increases during late folliculogenesis in Fshb^+/− females, these increases fail to occur in Fshb^−/− females. Remarkably, supplying a single dose of exogenous FSH activity to Fshb^−/− females is sufficient to increase Egfr and EGFR expression and to restore EGFR-dependent cumulus expansion and oocyte maturation. These studies show that FSH induces an increase in EGFR expression during late folliculogenesis and provide evidence that the FSH-dependent increase is necessary for EGFR physiological function. Our results demonstrate an unanticipated role for FSH in establishing the signaling axis that coordinates ovulatory events and may contribute to the diagnosis and treatment of some types of human infertility.Fertility in mammals depends on the coordinated execution of multiple events within the fully grown ovarian follicle at the time of ovulation (1, 2). The oocyte undergoes meiotic maturation, during which it progresses to metaphase II of meiosis and acquires the ability to begin embryonic development (3). Concomitantly, the layer of granulosa cells (GCs) immediately surrounding the oocyte, termed the “cumulus,” undergoes a process termed “expansion,” which is required for sperm to penetrate this layer and reach the oocyte (4–7). At the perimeter of the follicle, an inflammatory response associated with rupture of the follicular wall permits the cumulus–oocyte complex (COC) to escape from the follicle and enter the oviduct where fertilization will occur. These events are triggered by the preovulatory release of luteinizing hormone (LH), which acts on LH receptors (LHCGR) on the mural GCs that line the interior wall of the fully grown follicle (8).Recent studies have identified a key downstream effector of LH activity at ovulation. Binding of LH to LHCGR triggers the release of the EGF-related peptides amphiregulin (AREG, betacellulin (BTC), and epiregulin (EREG) (9–11). These bind to EGF receptors (EGFRs) located on both the mural and cumulus GCs (12–19) and activate MAPK3/1 as well as other signaling networks (20–28). Considerable evidence supports the view that the EGFR signaling mediates many or most ovulatory events. First, the release of the EGFR ligands follows the LH surge but precedes the LH-dependent responses (9–11). Second, EGF and the EGFR ligands can induce cumulus expansion and oocyte maturation in vitro, independently of LH (9, 10, 20, 29). Third, these events are impaired in mice bearing a hypomorphic Egfr allele that reduces EGFR activity by about one-half and in mice in which Egfr has been selectively inactivated in GCs through a targeted mutation (22, 23). Thus, the activation of EGFR signaling in GCs of mature follicles appears to be a major effector of the ovulatory response to LH.FSH binds to receptors located on GCs and induces the expression of numerous genes, including Lhcgr (8, 30). Lhcgr expression is impaired substantially in mice that lack either FSH, because of targeted mutation of the Fshb gene that encodes its β-subunit, or the FSH receptor and in humans bearing spontaneous mutations; these individuals fail to ovulate (31–34). Thus, the ovulatory response to LH depends strictly on the prior FSH-dependent expression of Lhcgr, and in this manner FSH indirectly controls the LHCGR-regulated release of the EGFR ligands. We report here that FSH also drives an increase in EGFR expression during late folliculogenesis and provide evidence that this increase is essential to enable the ovulatory response to EGF. By coordinating the expression of EGFR and the release of its ligands, FSH endows full-grown follicles with the capacity to activate EGFR signaling at ovulation.     

The epidermal growth factor receptor family

The epidermal growth factor receptor family consists of four receptor genes and at least 11 ligands, several of which are produced in different protein forms. They create an interacting system that has the ability to receive and process information that results in multiple outputs. The family has an important role in directing and coordinating many normal processes, including growth and development, normal tissue turnover and wound healing. Its members are also aberrantly activated by overexpression or mutation in many common human tumour types and as such have been the target for anticancer drug development.     

Caveolin-1 negatively regulates a metalloprotease-dependent epidermal growth factor receptor transactivation by angiotensin II

A metalloprotease, ADAM17, mediates the generation of mature ligands for the epidermal growth factor receptor (EGFR). This is the key signaling step by which angiotensin II (AngII) induces EGFR transactivation leading to hypertrophy and migration of vascular smooth muscle cells (VSMCs). However, the regulatory mechanism of ADAM17 activity remains largely unclear. Here we hypothesized that caveolin-1 (Cav1), the major structural protein of a caveolae, a membrane microdomain, is involved in the regulation of ADAM17. In cultured VSMCs, infection of adenovirus encoding Cav1 markedly inhibited AngII-induced EGFR ligand shedding, EGFR transactivation, ERK activation, hypertrophy and migration, but not intracellular Ca²⁺ elevation. Methyl-β-cyclodextrin and filipin, reagents that disrupt raft structure, both stimulated an EGFR ligand shedding and EGFR transactivation in VSMCs. In addition, non-detergent sucrose gradient membrane fractionations revealed that ADAM17 cofractionated with Cav1 in lipid rafts. These results suggest that lipid rafts and perhaps caveolae provide a negative regulatory environment for EGFR transactivation linked to vascular remodeling induced by AngII. These novel findings may provide important information to target cardiovascular diseases under the enhanced renin angiotensin system.     

The serine/threonine kinase cyclin G-associated kinase regulates epidermal growth factor receptor signaling

Cyclin G-associated kinase (GAK) is a serine/threonine kinase that features high homology outside its kinase domain with auxilin. Like auxilin, GAK has been shown to be a cofactor for uncoating clathrin vesicles in vitro. We investigated epidermal growth factor (EGF) receptor-mediated signaling in cells, in which GAK is down-regulated by small hairpin RNAs. Here, we report that down-regulation of GAK by small hairpin RNA has two pronounced effects on EGF receptor signaling: (i) the levels of receptor expression and tyrosine kinase activity go up by >50-fold; and (ii) the spectrum of downstream signaling is significantly changed. One very obvious result is a large increase in the levels of activated extracellular signal-regulated kinase 5 and Akt. These two effects of GAK down-regulation result from, at least in part, alterations in receptor trafficking, the most striking of which is the persistence of EGF receptor in altered cellular compartment along with activated extracellular signal-regulated kinase 5. The alterations resulting from GAK down-regulation can have distinctive biological consequences: In CV1P cells, down-regulation of GAK results in outgrowth of cells in soft agar, raising the possibility that loss of GAK function may promote tumorigenesis.     

RNA干扰技术抑制非小细胞肺癌表皮生长因子受体的表达

目的　观察RNA干扰技术是否能有效抑制非小细胞肺癌 (NSCLC)细胞株SPC A 1细胞表皮生长因子受体 (EGFR)的表达。方法　体外化学合成EGFR序列特异性双链RNA(dsRNA) ,与Lipofectamine 2 0 0 0结合后转染细胞 (分 4个组 ,A组 :加入无血清DMEM 5 0 0 μl;B组 :加入Lipofectamine2 0 0 0稀释液 2 5 0 μl及无血清DMEM 2 5 0 μl;C组 :加入非特异性dsRNA/Lipofectamine复合物 5 0 0 μl;D组 :加入dsRNA EGFR/Lipofectamine复合物 5 0 0 μl) ,用Westernblot和流式细胞仪检测EGFR表达。流式细胞仪测细胞周期 ,结合集落形成、化疗敏感性分析观察SPC A 1细胞生物学特性的改变。结果　与A组比较 ,D组EGFR数量减少了 71 31% (P <0 0 0 1) ,B组和C组分别降低了 9 0 %和 16 2 % (P >0 0 5 )。与A组比较 ,D组细胞生长抑制了 78 3% ,集落形成抑制了 6 6 8%。D组G0 G1期细胞百分数较A组增加了 17 4 8% ,D组进入S期的细胞百分数较A组减少了 19 2 0 %。据Origin 6 0计算的IC50 ,dsRNA EGFR可将细胞对顺铂的敏感性提高约 7倍。结论　dsRNA EGFR可有效抑制SPC A 1细胞EGFR表达 ,将更多的细胞阻滞在G0 G1期 ,抑制细胞增生 ,提高细胞对顺铂的敏感性 ,RNA干扰技术为NSCLC基因治疗提供了新策略。     

siRNA mediated the type 1 insulin-like growth factor receptor and epidermal growth factor receptor silencing induces chemosensitization of liver cancer cells

Purpose This study was to investigate if downregulation of IGF1R and EGFR by RNA interference (RNAi) would sensitize human liver cancer cells (HEPG2, Huh7 ) to adriamycin. Methods HEPG2, Huh7 cell lines were transfected IGF1R siRNAs and EGFR siRNAs and IGF1R or EGFR mRNA level was determined by RT-PCR and Western-blot analysis. We investigated the effects of the adriamycin-induced apoptosis of these cells by TUNEL assay. Also we analyze caspase3, 8 and the phosphorylation levels of Akt and Erk by Western-blot. The p53 effect of adriamycin-induced cell death by inhibitors of EGFR/IGF1R is investigated by cell growth curves. Results Transfection of an IGF1R and EGFR siRNAs resulted in substantial loss of IGF1R and EGFR mRNA of HEPG2, Huh7 cells relative to the control case. EGFR siRNA and IGF1R siRNA treatments increased the adriamycin-induced apoptosis of these cells. IGF1R siRNA and EGFR siRNA enhance a caspase-dependent cell death program. The phosphorylation levels of Akt and Erk were reduced by the combination of the two agents. The facilitation of adriamycin-induced cell death by inhibitors of EGFR/IGF1R is p53-independent. Conclusions The results indicate that the siRNA for IGF1R has a great potential for cancer therapy when combined with either a chemotherapeutic agent or siRNAs that targets EGFR.     

老年前列腺恶性增生切除睾丸后唾液表皮生长因子水平的变化

目的　探讨睾丸切除对人唾液表皮生长因子（ＥＧＦ） 分泌的影响。方法：应用放射免疫测定（ＲＩＡ） 方法对１１例因前列腺癌切除睾丸和２２ 例正常人唾液ＥＧＦ 含量进行了检测。结果：人睾丸切除后人唾液ＥＧＦ 含量１３－３２ ±４ ．３３（ｎｇ／１５ ｍｉｎ） ,与术前１４－０７ ±４ ．５０（ｎｇ／１５ ｍｉｎ） 比较,ｔ＝ １ ．７２５２ ,０ ．２ ＞ Ｐ＞ ０ ．１ ;与正常男性唾液ＥＧＦ 含量１３－９１ ±３ ．９０（ｎｇ／１５ｍｉｎ） 比较,ｔ ＝ ０ ．３９４６ ,Ｐ＞ ０ ．２５ ;均无显著性差别。结论：睾丸缺失对ＥＧＦ 影响不明显     

Targeting the epidermal growth factor receptor in metastatic colorectal cancer

Although significant advances have been made in the treatment of metastatic colorectal cancer (CRC), prognosis remains poor, with a 5-year survival of less than 10%. Monoclonal antibodies that target the epidermal growth factor receptor (EGFR) have shown clinical benefit as single agents and in combination with standard chemotherapy in the refractory setting, with tolerable toxicity. This article will discuss the role of the EGFR pathway in the pathogenesis of CRC, the data supporting the current use of cetuximab and panitumumab in the treatment of CRC, and clinical trials of EGFR tyrosine kinase inhibitors in CRC. Novel strategies of targeting the EGFR pathway to improve efficacy, as well as ongoing research in identifying molecular predictors of response to anti-EGFR agents, will also be reviewed.     

Gastric mucosal cell protection by epidermal growth factor in primary monolayer culture of guinea pig gastric mucous cells

Background. Epidermal growth factor (EGF) has an anti-ulcer effect, but the mechanisms of this gastric mucosal protection are incompletely understood. We have suggested the importance of mucin as a mucosal protectant. We investigated whether increased mucin biosynthesis might be involved in the gastric mucosal protection conferred by EGF. Methods. EGF and then ethanol were added to primary monolayer cultures of guinea pig gastric mucous cells, in which factors such as gastric acid and gastrointestinal hormones were excluded. Mucin and prostaglandin E₂ (PGE₂) were assayed. Results. Cytoprotection induced by EGF was demonstrated. Mucin biosynthesis and PGE₂ release were both significantly increased by EGF. When endogenous PGE₂ synthesis was inhibited by pretreatment with 10^–5M or 10^–4M indomethacin (IND), mucin biosynthesis was still significantly increased by EGF. Ethanol-induced cell damage was concentration-dependent in cultures with no other additions (normal PGE₂ and mucin biosynthesis). Damage by ethanol was decreased by EGF pretreatment (increased PGE₂ and mucin biosynthesis). Damage by ethanol was increased by 10^–5M IND pretreatment (decreased PGE₂; normal mucin biosynthesis) and by 10^–4M IND pretreatment (decreased PGE₂ and mucin biosynthesis). Ethanol-induced damage was decreased by EGF pretreatment even in the presence of 10^–5M and 10^–4M IND (decreased PGE₂; increased mucin biosynthesis). Conclusions. Increased mucin biosynthesis, induced by EGF independently of PGE₂, protects gastric mucous cells.