Structure, function and gene expression of epithelial mucins

In this review the main characteristics, i.e., structure, function and gene expression, of the different mucins are discussed. Mucin-type molecules consist of a core protein moiety (apomucin) where a number of carbohydrate chains are attached to serines and threonines by glycosidic bonds. O-linked carbohydrates form up to 80% of the molecule and the length of the glucidic side chains varies from one to more than 20 residues. At least eight mucin-like genes have been isolated so far, and the main characteristic is the presence of a central domain composed of a variable number of "tandem repeats". The sequence homology of the central domain among the different members of the mucin-type family is limited, indicating that this internal domain is unique for each mucin. Thanks to the integrated results of genetic, immunological and biochemical studies, it is now possible to identify eight apomucin genes, namely MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7. MUC1 is the best characterized mucin and it is expressed on the apical surface of most polarized epithelial cells. The MUC1 gene has been cloned and sequenced. The MUC2 gene encodes a typical secretory gel-forming mucin which represents the predominant form in human intestinal and colon tissues. Another intestinal mucin is MUC3. The MUC4, MUC5AC and MUC5B genes have been isolated from a bronchial tissue cDNA library. The MUC4 and MUC5AC genes are mainly expressed in the respiratory tract, in gastric and reproductive mucosa, while MUC5B is highly detectable only in the bronchial glands. The MUC6 gene is expressed by gastric tissue and, recently, MUC7 has been cloned and sequenced using a salivary cDNA library.     

Expression cloning of gastric mucin complementary DNA and localization of mucin gene expression

BACKGROUND & AIMS: Secretory mucins play an important role in gastric cytoprotection and are derived from a heterogeneous family of genes. The aim of this study was to determine the specific type and location of mucin gene expression in the human stomach. METHODS: Expression cloning was performed by screening a human gastric complementary DNA expression library with antisera against deglycosylated gastric mucin. RNA analysis and immunohistochemistry were used to quantify and localize mucin gene expression. RESULTS: Sequencing of positive clones revealed two clones containing tandem repeats. The first contained a 169-amino acid repeat and was named MUC6 (as previously described). The second contained the same 8-amino acid repeat consensus sequence (APTTSTTS) as complementary DNAs previously isolated from a tracheobronchial complementary DNA library and was labeled MUC5 (or MUC5AC). RNA analysis indicated that the gastric epithelium contains high levels of MUC5 and MUC6 messenger RNA with little or no MUC2, MUC3, and MUC4 messenger RNA. Immunohistochemical analysis showed that surface mucous cells of the cardia, fundus, and antrum expressed MUC5 peptide. In contrast, MUC6 peptide expression was limited to mucous neck cells of the fundus, antral-type glands of the antrum and cardia, and Brunner's glands of the duodenum. CONCLUSIONS: MUC5 and MUC6 represent major secretory mucins in the stomach and are localized to distinct cell types.     

Suppression of sigma spindle electroencephalographic activity as a measure of transient arousal after spontaneous and occlusion-evoked sighs and startles

Gastric M1 mucin and the MUC5AC gene show a similar oncofetal expression in the colon. Our aim was to determine whether M1 mucin is the product of the MUC5AC gene. A recombinant baculovirus encoding the C-terminal portion of the MUC5AC gene as a fusion protein was isolated and the immunoreactivity of the recombinant mucin (rM) toward M1 antibodies studied. Chicken antibodies also were raised against purified rM. Besides its reactivity with L56/C, a serum recognizing the bacterially expressed MUC5AC gene product, rM was endowed with M1 immunoreactivity: (i) rM-expressing cells were stained specifically with anti-M1 serum and with the monoclonal antibody (MAb) 21M1, defining the M1-f epitope; (ii) both L56/C and anti-M1 antibodies recognized the same bands in immunoblots of rM-containing cell extracts; (iii) the 21M1 antibody reacted with rM in an immunoradiometric assay. Among the 7 M1 epitopes, M1-f was the only one encoded by the 3' portion of the MUC5AC gene. It was the only epitope detected in a native mucin M1-derived 170 kDa bromelain proteolytic fragment. Furthermore, the staining patterns of human tissues obtained with either anti-rM chicken antibodies or anti-M1 antibodies were identical. We conclude that M1 immunoreactivity is encoded at least in part by the MUC5AC gene.     

A novel gastric-cancer-associated mucin antigen defined by a monoclonal antibody A3D4

De-glycosylation of mucins may expose new tumor-associated core protein epitopes. In this study, to attempt to develop useful markers for gastric cancers, we have purified and de-glycosylated gastric mucin and tried to establish monoclonal antibodies (MAbs). A MAb designated A3D4 among established MAbs was shown to react with gastric cancer with high frequency, but not with normal gastric epithelium. Among normal digestive organs, only the colon and gall bladder were positive for MAb A3D4. The incidence of positivity in gastric cancer was 75% for intestinal-type adenocarcinoma (n = 28), 40% for solid-type adenocarcinoma (n = 5) and 33% for signet/scirrhous-type adenocarcinoma (n = 15). Interestingly, adenoma and intestinal metaplasia (IM) with chronic gastritis or peptic ulcer were negative for MAb A3D4, whereas 8 out of 13 cases (62%) of IM with gastric cancer was positive. Western-blot analysis using the lysate from normal colon tissues revealed a high-molecular-weight (> 300-kDa) smear-like band. Immunohistochemical analysis indicated that the reactivity of MAb A3D4 was clearly increased when tissue sections were pre-treated with periodic acid or O-glycanase, while it was decreased by pre-treatment with trypsin or protease V8. There was no reactivity with the synthetic peptide encompassing the tandem-repeat sequence of MUC2 or MUC3. These data suggest that MAb A3D4 detects a novel gastric-cancer-associated mucin antigen whose epitope may be peptide in nature.     

Aberrant expression of MUC5AC and MUC6 gastric mucin genes in colorectal polyps

Altered mucin glycosylation and the de novo appearance of gastric mucin antigens have been described in colonic adenomas. The purpose of our study was to determine if expression of the gastric mucin genes MUC5AC and MUC6 occurs in colorectal adenomas and whether this correlates with histopathologic criteria of malignant potential. Immunohistochemical staining using antibodies against MUC5AC and MUC6 tandem repeat synthetic peptides was performed on specimens of normal colon mucosa (n = 26), hyperplastic polyps (n = 9) and adenomatous polyps (n = 111). Mucin mRNA levels were determined using RNase protection assays using riboprobes corresponding to unique non-repetitive sequences. MUC5AC and MUC6 staining were rarely detected and of low intensity in normal colon and hyperplastic polyps. The number of immunoreactive polyps and intensity of MUC5AC and MUC6 staining were greatest in larger adenomas of moderate villous histology and dysplasia. MUC5AC and MUC6 staining tended to decrease in highly villous polyps with severe dysplasia. Increased MUC5AC mRNA levels were found in 26/45 of adenomas tested compared with 0/9 normal colon specimens. MUC6 mRNA levels were found in 20/45 of adenomas compared with 1/9 normal colon specimens. MUC5AC and MUC6 mRNA were present more frequently and at higher levels in polyps with intermediate stages of size, villous histology and dysplasia. We conclude that aberrant expression of MUC5AC and MUC6 mucin genes is likely responsible for an expanded repertoire of mucin antigen expression in colorectal neoplasia.     

Gastropathies in the Lundehund. II. A study of mucin profiles

The mucin profiles of the gastric mucosa in Lundehunds suffering from intestinal lymphangiectasia were examined and compared to the mucin profiles in control dogs from other breeds. A previous study performed on this material had shown that all examined Lundehunds had gastritis and about 30% had gastric carcinoma. Neutral and acid mucins were identified using the periodic acid-Schiff (PAS) and Alcian blue (pH 2.5) periodic acid-Schiff (AB-PAS) methods. The acid mucins were divided into sialomucins and sulfomucins based on their reaction with high-iron diamine Alcian blue, pH 2.5 (HID-AB). In Lundehunds with chronic atrophic gastritis in the fundic and body regions the surface and foveolar epithelium showed a predominantly normal mucin profile although some Lundehunds had a reduced mucin content. The mucous neck cells extended from below the gastric foveolae towards the muscularis mucosae. Morphometric examination showed that the abnormal presence of mucous neck cells occupied 41% of the height of the gastric mucosa in Lundehunds compared to only 19% in the control dogs (p < 0.05). Of the four Lundehunds with gastric carcinoma, two possessed neoplastic cells that contained minimal or no mucins. The amount and type of mucin in the neoplastic cells of the remaining two Lundehunds varied both between individuals and within a neoplasm. This study shows that the abnormal presence of mucous neck cells and the associated pseudopyloric metaplasia comprised the predominant changes in the gastric mucin profiles of Lundehunds.     

Gastric mucous neck cell and intestinal goblet cell phenotypes in gastric adenocarcinoma

AIM: To investigate the phenotype of cells comprising diffuse and intestinal-type gastric cancers using monoclonal antibodies to two antigens. One antigen (designated D10) is characteristic of gastric mucous neck cells, cardiac glands, pyloric glands, and Brunner's glands. The second antigen (designated 17NM) is specific to the mucous vacuole of intestinal goblet cells. METHODS: Thirty two gastrectomy specimens with adenocarcinoma were studied. Serial paraffin sections were stained immunohistochemically for D10 and 17NM and histochemically for acid and neutral mucins. The cancers were classified histologically as of either diffuse or intestinal type according to Lauren. RESULTS: Of 15 diffuse-type gastric carcinomas, 11 showed the majority of cancer cells staining for D10 while four were typical signet ring cell cancers staining predominantly for 17NM; five tumours displayed both phenotypes with the two phenotypes segregated in different areas of the tumours. In contrast, of 16 intestinal-type cancers, six expressed 17NM, three D10, five neither antigen, and two expressed both antigens. One indeterminate-type cancer expressed both antigens. The staining of individual cells for D10 and 17NM was mutually exclusive in both diffuse and intestinal types. In contrast to the diffuse cancers, intestinal-type cancers typically expressed either antigen only in occasional small groups of cells and individual cells. CONCLUSIONS: In disease, the gastric stem cell can assume the capacity of the duodenal stem cell for divergent differentiation into either intestinal goblet cells (for example, as in intestinal metaplasia) or Brunner's gland cells (for example, as in pyloric gland/Brunner's gland metaplasia). With neoplastic transformation, this potential for divergent differentiation is maintained and gives rise to diffuse-type cancers that display either the D10 phenotype, the 17NM phenotype, or the clonal expression of both phenotypes. In the more cell cohesive (intestinal-type) tumours, differentiation for antigen expression is poorly developed and more frequently directed towards the intestinal goblet cell phenotype.     

Mucin gene expression in ovarian cancers

Ovarian cancer is a highly lethal disease with metastases present in the majority of patients at the time of diagnosis. The molecular mechanisms underlying the metastatic process of this cancer are not well understood. One family of cell-associated and secreted glycoproteins, the mucin glycoproteins, has been implicated in events leading to metastasis of several epithelial cancers including gastrointestinal and lung cancers. The purpose of this study was to characterize mucin gene expression in ovarian cancers and relate expression to tumor histology, stage, and patient survival. RNA was isolated from 29 epithelial ovarian cancers, 1 neuroendocrine carcinoma, 3 mixed mesodermal tumors, and two transformed, yet nonmalignant, ovarian epithelial cell lines. The expression of mucin genes, MUC1, 2, 3, 4, 5AC and 5B, was determined by northern analyses. Epithelial ovarian cancers expressed several mucins including MUC1, 2, 4, and 5AC; MUC3 and 5B were rarely expressed. In contrast, the transformed nonmalignant ovarian epithelial cell lines expressed only MUC1 and 5AC. Although there was no correlation of mucin expression with tumor histology, there was a significant decrease in expression of MUC3 and MUC4 with increasing cancer stage (P < 0.05). In addition, a trend toward improved patient survival occurred with increased expression of MUC4. These observations suggest a relationship between mucin gene expression and the metastatic process in epithelial ovarian cancers. Additional investigation of MUC3 and MUC4 in ovarian cancers may lead to new approaches for early detection and therapy.     

Cholinergic dependence of a cortical neuronal mechanism that supports Pavlovian eyeblink conditioning

Mucin glycoproteins play a key role in the normal function of the airway epithelium. We examined the expression of mucin genes, MUC3, 4, 5AC, 5B, 6, 7, and 8 in human fetal tissues to establish the localization and age of onset of expression of each mucin gene during human development. We detected expression of MUC4, 5AC, 5B, and 7 in the mid-trimester airway epithelium but did not detect expression of MUC3, 6, or 8. MUC4 was expressed in the trachea and large airways in the majority of cells in the airway epithelium. Expression of MUC5AC was only seen in individual goblet cells in the trachea, while MUC5B was expressed in the surface epithelium of the trachea at 13 wk but was largely restricted to submucosal glands by 23 wk of gestation.     

Mucin gene expression in biliary epithelial cells

BACKGROUND/AIMS: In recent years considerable advances have been made in our knowledge of human mucin genes. Although analysis of their genomic organization is still in progress, the pattern of their expression in different human mucosae is now fairly well established. However, little is known about their expression in the biliary tree. In this study we determined the pattern of expression of the different human mucin genes in gallbladder biliary epithelial cells, intrahepatic bile ducts and liver. METHODS: Two complementary methods were used: Northern-blot and in situ hybridization analyses. The experiments were performed with eight probes corresponding to MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6 and MUC7. RESULTS: Our results revealed a strong mRNA expression of MUC3, MUC6 and MUC5B, a weak expression of MUC1, MUC5AC and MUC2, and no expression of MUC4 and MUC7. Surprisingly, MUC3, which was the gene which was most expressed in the biliary tree, was also found in hepatocytes, suggesting another function for the MUC3 protein than that of a secreted mucin. CONCLUSIONS: We conclude that MUC3, MUC6 and MUC5B were the main mucin genes expressed in biliary epithelial cells.     

Developmental mucin gene expression in the human respiratory tract

The epithelial surface of the respiratory tract is coated with a protective film of mucus secreted by epithelial goblet and submucosal gland cells. Histology of the airway mucosa and composition of secretions during the second trimester of fetal life are known to differ from the normal adult in that these secretions show similarities with those of hypersecretory disorders. To provide information regarding cell-specific expression of mucin genes and their relation to developmental patterns of epithelial cytodifferentiation, we studied the expression of eight different mucin genes (MUC1-MUC4, MUC5AC, MUC5B, MUC6, MUC7) in human embryonic and fetal respiratory tract using in situ hybridization. These investigations demonstrated that MUC4 is the earliest gene expressed in the foregut at 6.5 wk, followed by MUC1 and MUC2 from 9. 5 wk of gestation in trachea, bronchi, epithelial tubules, and terminal sacs before epithelial cytodifferentiation. In contrast, MUC5AC, MUC5B, and MUC7 are expressed at later gestational ages concomitant with epithelial cytodifferentiation. During this developmental stage, MUC1 and MUC4 mRNAs are located in goblet and ciliated cells, whereas MUC2 mRNAs are located in basal and goblet cells. MUC5AC expression is confined to goblet cells. In the submucosal glands, MUC2 mRNAs are located in both mucous and serous cells, whereas MUC5B and MUC7 mRNAs are expressed in mucous and in serous cells, respectively. These data suggest distinct developmental roles for MUC1, MUC2, MUC4, MUC5AC, MUC5B, and MUC7 in the elongation, branching, and epithelial cytodifferentiation of the respiratory tract during ontogenesis. Distinct patterns of mucin gene expression are also likely to play an important role in regulating appropriate epithelial cell proliferation and cytodifferentiation in adult airway mucosa as it is indicated by aberrant expression in hypersecretory disorders.     

Molecular characterization of an inwardly rectifying K+ channel from HeLa cells

Retinoid-deficient cultures of airway epithelial cells undergo squamous differentiation. Treatment of such cultures with retinoic acid (RA) leads to restoration of the mucous phenotype. The purpose of our study was to characterize the cellular and molecular changes following RA treatment of retinoid-deficient human tracheobronchial epithelial cell cultures. Of particular interest was to determine when during the conversion of the squamous to the mucous phenotype the mucin genes MUC2, MUC5AC, and MUC5B were expressed. We used cornifin alpha and secreted mucin as markers to monitor the squamous and mucous phenotypes, respectively. Our studies showed that the RA responsiveness of the cultures progressively decreased with protracted retinoid deficiency, requiring higher RA concentrations to restore the mucous phenotype. Within 12 h after the start of RA treatment, cornifin alpha expression decreased, signaling the beginning of a change in cellular phenotype. At 24 h after addition of RA to the cultures, a significant number of mucous cells appeared, and at 72 h mucin was secreted in measurable amounts. Induction of mucin gene expression occurred sequentially: MUC2, MUC5AC, and MUC5B mRNAs were upregulated at 24, 48, and 72 h, respectively. When cultures maintained in 10(-8) M RA were treated with 10(-6) M RA, MUC2 but not MUC5AC and MUC5B mRNA levels were upregulated within 6 h. Our study indicates that MUC2 mRNA is an early marker of mucous differentiation, whereas MUC5AC and MUC5B mRNAs are expressed during more advanced stages of mucous differentiation. Our studies further suggest that each of the mucin genes is regulated by distinct mechanisms.     

Comorbidities and prediction of length of hospital stay

Columnar epithelium-lined esophagus (Barrett's esophagus) is an acquired disorder associated with a high incidence of adenocarcinoma of the lower esophagus. Columnar epithelium resembling intestinal metaplasia (IM) is especially important, since it is considered to be a premalignant condition. The aim of this study was to define the sulfated carbohydrate chain of mucin and its core peptide profile in Barrett's esophagus (BE) and to compare it with the profile in Barrett's adenocarcinoma and lower esophageal adenocarcinoma. The sulfated carbohydrate chain was not expressed in 16 specimens of normal esophageal epithelium, but in BE, it was expressed in 50% (8/16) of the specimens. This chain was detected in 100% (7/7) of esophageal adenocarcinoma specimens, including four cases of Barrett's adenocarcinoma. These data suggest that the sulfated carbohydrate chain may be associated with malignant phenotype of the esophagus. MUC1 core peptide was positive in 87% (13/15) of BE specimens and in 29% (2/7) of the esophageal adenocarcinoma specimens. MUC2 core peptide was present in 57% (8/14) and 43% (3/7) of these specimens, respectively. These data suggest that Barrett's epithelium, which is similar to IM, but not normal esophageal epithelium, expresses the sulfated sugar chain which is known to be present in gastric IM and colonic mucosa. However, there was no significant correlation between the expression of the sulfated sugar chain and the expression of either mucin core peptide MUC1 or MUC2. Thus, this carbohydrate chain may be expressed on as yet unidentified core proteins, other than MUC1 or MUC2 core peptide, in BE and esophageal adenocarcinoma. Identification of these proteins may be very important in helping to detect premalignant status in BE.     

Selection of tumor antigens as targets for immune attack using immunohistochemistry: protein antigens

The relative expression of mucin antigens MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, and MUC7 and glycoprotein antigens KSA, carcinoembryonic antigen, prostate-specific membrane antigen (PSMA), HER-2/neu, and human chorionic gonadotropin-beta on different cancers and normal tissues is difficult to determine from available reports. We have compared the distribution of these antigens by immunohistology on a broad range of malignant and normal tissues. MUC1 expression was most intense in cancers of breast, lung, ovarian, and endometrial origin; MUC2 was most intense in cancers of colon and prostate origin; and MUC5AC was most intense in cancers of breast and gastric origin. MUC4 was intensely expressed in 50% of cancers of colon and pancreas origin, and MUC3, MUC5B, and MUC7 were expressed in a variety of epithelial cancers, but not so intensely. KSA was intensely and uniformly expressed on all epithelial cancers; carcinoembryonic antigen was expressed in most cancers of breast, lung, colon, pancreas, and gastric origin; and PSMA was expressed only in cancers of prostate origin. Human chorionic gonadotropin-beta was expressed on the majority of sarcomas and cancers of breast, lung, and pancreas origin, although intense staining was not seen. Staining on normal tissues was restricted to one or many normal epithelial tissues ranging from MUC3, MUC4, and PSMA, which were expressed only on epithelia of pancreas, stomach, and prostate origin, respectively, to MUC1 and KSA, which were expressed on most normal epithelia. Expression was restricted to the secretory borders of these epithelia while stroma and other normal tissues were completely negative. These results plus the results of the two previous papers (S. Zhang et al, Int. J. Cancer, 73: 42-49, 1997; S. Zhang et al., Int. J. Cancer, 73: 50-56, 1997) in this series provide the basis for selection of multiple cell surface antigens as targets for antibody-mediated attack against these cancers.     

Histogenetical investigations on adenocarcinomas of the esophagogastric junction. An immunohistochemical study

The presence of Pepsinogen II (PG II), gastral mucin (2B5), CA 19-9, BW 494 and Cytokeratin 20 (CK 20) was investigated in 69 adenocarcinomas of the esophagogastric junction (15 carcinomas in Barrett's esophagus, 9 distal esophageal carcinomas, 31 carcinomas of the cardia and 14 subcardial carcinomas). Evidence of gastric differentiation (expression of Pepsinogen II and/or gastric mucin) was found in more than 50% of the Barrett's carcinomas and the carcinomas of the cardia, but only in 20% of the subcardial carcinomas. High rates of antigen expression were found for the "intestinal" markers CA 19-9 (between 55.5% and 100%) and BW 494 (between 42.9 and 86.7%). CK-20 expression was detected to a significantly higher degree in Barrett's carcinomas (73.3%) than in the other groups (between 29% and 44.4%). These data indicate that the distribution of adenocarcinomas with gastric and/or intestinal differentiation at the esophagogastric junction forms a continuum without clear-cut borders.     

Mucin antigen expression in gastric carcinomas of young and old adults

The striking differences in the histological features of gastric cancers in young and old adults have been thought to be related to differences in the biological behavior of these cancers. Recently, a new grading system (Goseki's classification) showed that the prognosis of the patient is particularly related to the mucin content of the carcinoma. In this study, we examined differences in mucin antigen expression in cancers from young and old adults and whether antigen expression is related to the clinical outcome. The expression of two mucin core proteins (DF3 antigen [MUC1 gene product] and MRP antigen [MUC2 gene product] and a mucin-type carbohydrate antigen [sialosyl-Tn; STn]) was examined immunohistochemically in gastric cancers from 69 young adults (30 to 39 years of age) and 110 old adults (80 to 89 years of age). The incidence rates of the three histological types (tubular adenocarcinoma, poorly differentiated adenocarcinoma, and signet-ring cell carcinoma) were different in the young and old adults. However, among the mucin antigens examined, only DF3 showed significantly higher frequency of expression in the old adults, and the difference was seen only in tubular adenocarcinomas (young, 43%; old, 68%) and poorly differentiated adenocarcinomas (young, 19%; old, 49%). In these two histological types, there was no difference in the frequency of MRP or STn expression between the young and old adults, although the old adults showed a high incidence of intestinal metaplasia that was positive for both antigens. Signet-ring cell carcinomas showed no significant difference in expression rates of the three antigens in young and old adults, but there were significantly higher expression rates in young patients for both MRP (young, 67%; old, 65%) and STn (young, 71%; old, 57%) and a lower rate of DF3 expression (young, 0%; old, 14%). In both young and old adults, the patients with DF3-positive carcinomas showed significantly poorer survival than those without DF3 expression, whereas there was not significant difference in the survival of the patient groups with positive and negative MRP or STn reactivity. In conclusion, the expression of DF3 was influenced by the age of patients and was related to the outcome. In contrast, MRP and STn expression was related more to the histological pattern of the tumor than to the age of the patient and did not correlate with the outcome.     

SPECT brain perfusion abnormalities in mild or moderate traumatic brain injury

The accumulation of wild-type p53 protein results in two pathways, cell cycle G1 arrest by p21WAF1/CIP1/SDI1 and apoptosis inhibited by bcl2, which together carry out the tumor suppressor function. Since genetic alterations of p53 are frequently observed in gastric cancers, the expression of p21 and bcl2 may be altered in gastric carcinogenesis. We therefore analyzed normal mucosa, nondysplastic lesions, hyperplastic polyps, adenomas and carcinomas of the human stomach using immuno-histochemistry, polymerase chain reaction-single-strand conformation polymorphism and DNA sequencing. In normal gastric mucosa, the expression of p21, bcl2 and p53 was topographically restricted: a) p21 expression was limited to foveolar epithelial cells; b) bcl2 and p53 expression was confined to only a few regenerative epithelial cells of the mucous neck region. In chronic gastritis or intestinal metaplasia, topographic expression became more obvious. This topographic expression was altered in hyperplastic polyps and adenomas. Hyper-plastic polyp showed an increased p21 and p53 expression with no bcl2 expression. Where as bcl2 expression increased and extended up parabasal and superficial dysplastic epithelium, p21 expression increased and was limited to surface dysplastic epithelium. Weak p53 expression was in full thickness of dysplastic epithelium. p21 and bcl2 expression in adenoma was higher than in intestinal type of carcinoma. In carcinomas, this topography was abrogated, but p53 mutation (36%) was present. There was no relationship between p53, p21 and bcl2 expression. As a result, in normal gastric epithelial cells, there was a precisely ordered topographic pattern of p21, bcl2 and wild-type p53 expression that becomes disordered during neoplasia. These results suggest that altered cell cycle and apoptosis control by wild-type p53 and its mediators appears to be an early event in gastric carcinogenesis that may facilitate tumor progression.