Sucrase-isomaltase expression in chronic ulcerative colitis and dysplasia

Ulcerative Colitis: Novel Epithelial Insights Provided by Single Cell RNA Sequencing

Ulcerative Colitis (UC) is a chronic inflammatory disease of the intestinal tract for which a definitive etiology is yet unknown. Both genetic and environmental factors have been implicated in the development of UC. Recently, single cell RNA sequencing (scRNA-seq) technology revealed cell subpopulations contributing to the pathogenesis of UC and brought new insight into the pathways that connect genome to pathology. This review describes key scRNA-seq findings in two major studies by Broad Institute and University of Oxford, investigating the transcriptomic landscape of epithelial cells in UC. We focus on five major findings: (1) the identification of BEST4 + cells, (2) colonic microfold (M) cells, (3) detailed comparison of the transcriptomes of goblet cells, and (4) colonocytes and (5) stem cells in health and disease. In analyzing the two studies, we identify the commonalities and differences in methodologies, results, and conclusions, offering possible explanations, and validated several cell cluster markers. In systematizing the results, we hope to offer a framework that the broad scientific GI community and GI clinicians can use to replicate or corroborate the extensive new findings that RNA-seq offers.

Sucrase-Isomaltase Expression in Dysplasia Associated With Barrett's Esophagus and Chronic Gastritis

Aberrant cytoplasmic sucrase-isomaltase has been detected in colonic neoplasia, including dysplasia in ulcerative colitis. We investigated expression by immunostaining in 28 cases of Barrett's esophagus and 67 cases of chronic gastritis. Staining location (membrane or cytoplasmic) and percent positivity (< 1% = 0; 1-50% = 1+; > 50% = 2+) were record ed. Fifteen cases with Barrett's esophagus were negative for dysplasia, 1 was indefinite, and 12 were positive. All demonstrated surface membrane staining, while 2 of the 15 neg ative (1+) cases, 0 of the 1 indefinite case, and 11 of the 12 dysplastic (2+ in 7) cases revealed cytoplasmic positivity (P < .001). In chronic gastritis (23 were negative, 5 were indefinite, and 39 were positive) all revealed surface membrane staining, whereas cyto plasmic positivity was present in 1 of 23 negative (1+) cases, 1 of 5 indefinite cases, and 37 of 39 dysplastic (2+ in 18) cases (P < .001). In Barrett's esophagus and chronic gastri tis, cytoplasmic sucrase-isomaltase expression strongly correlates with the presence of dys plasia. Int J Surg Pathol 2(4).-281-286, 1995

The multiple roles of sucrase-isomaltase in the intestinal physiology

Osmotic diarrhea and abdominal pain in humans are oftentimes associated with carbohydrate malabsorption in the small intestine due to loss of function of microvillar disaccharidases. Disaccharidases are crucial for the digestion and the subsequent absorption of carbohydrates. This review focuses on sucrase-isomaltase as the most abundant intestinal disaccharidase and the primary or induced pathological conditions that affect its physiological function. Congenital defects are primary factors which directly influence the transport and function of sucrase-isomaltase in a healthy epithelium. Based on the mutation type and the pattern of inheritance, a mutation in the sucrase-isomaltase gene may exert a variety of symptoms ranging from mild to severe. However, structure and function of wild type sucrase-isomaltase can be also affected by secondary factors which influence its structure and function either specifically via certain inhibitors and therapeutic agents or generally as a part of intestinal pathogenesis, for example in the inflammatory responses. Diagnosis of sucrase-isomaltase deficiency and discriminating it from other gastrointestinal intolerances can be latent in the patients because of common symptoms observed in all of these cases.

Here, we summarize the disorders that implicate the digestive function of sucrase-isomaltase as well as the diagnostic and therapeutic strategies utilized to restore normal intestinal function.

Is it possible to discriminate between neoplastic and nonneoplastic lesions in ulcerative colitis by magnifying colonoscopy?

BACKGROUND

Colitis-associated cancer/dysplasia is an intestinal tract condition that can affect the life expectancy of patients with ulcerative colitis. It is often difficult to detect neoplastic lesions. This study evaluated whether any endoscopic features are effective for distinguishing colitis-associated cancer/dysplasia from nonneoplastic lesions in patients with ulcerative colitis.

METHODS

The study involved 52 patients with 61 lesions treated at Hiroshima University Hospital between September 1999 and May 2012: 10 patients with 11 dysplastic lesions, 5 patients with 5 intramucosal carcinomas, 3 patients with 3 submucosal carcinomas, and 34 patients with 42 nonneoplastic lesions. All patients had undergone targeted biopsy. Endoscopic findings were compared between patients with biopsy-determined neoplasia and those with biopsy-determined nonneoplasia. Multivariate regression analysis was performed to identify magnifying chromocolonoscopy features predictive of neoplasia.

RESULTS

No significant difference was found in conventional endoscopy features between the neoplastic and nonneoplastic lesions. Under magnifying chromocolonoscopy, the pit density of the neoplastic lesions was found to be significantly greater than that of the nonneoplastic lesions (89% [17/19] versus 60% [25/42], respectively). Pit margins were more frequently irregular in the neoplastic lesions than in the nonneoplastic lesions (63% [12/19] versus 33% [14/42], respectively).

CONCLUSIONS

In differentiating between colitis-associated neoplastic and nonneoplastic lesions, focus should be on the high residual density of pits and irregular pit margins observed under magnifying chromocolonoscopy.

Study of p53 and bcl-2 Oncoproteins in Ulcerative Colitis with Dysplasia

BACKGROUND

Dysplasia in ulcerative colitis has been graded on haematoxylin and eosin stain using Riddle's criteria. This system was formed to nullify the inter-observer variation. Few cases of early dysplasia were missed when purely screened on morphology. This study was carried out to detect early dysplasia using p53 and bcl-2 oncoproteins.

METHODS

A retrospective study was carried out on paraffin blocks of 100 histologically diagnosed cases of ulcerative colitis at a large service hospital. Haematoxylin and Eosin stained (H &E) slides of these cases were re-examined as per standard techniques.

RESULTS

On correlating histological grades with p53 immunoscore it was found that 90.76% of cases graded as negative for dysplasia on H & E, got an immunoscore of 0 and other 9.24% cases which were graded as negative for dysplasia got a score 1+. This shows that the immunohistochemistry was able to pick up 6 cases, which were missed by routine histology. Nine out of 11 cases in which the pathologists could not rule out a dysplasia and graded them as indefinite (probably negative for dysplasia) got a score of 0. In these cases possibly the histological features may be construed as an acute inflammation or repair induced dysplasia which were suspicious for neoplastic dysplasia on routine histology sections. On analyzing our findings on bcl-2 immunohistochemistry it was seen that there was no significant concordance (p>0.05) of immunoscore with the grades of dysplasia estimated morphologically.

CONCLUSION

Our study recommends that p53 should be used as regular immunohistochemical marker while grading the dysplasia of ulcerative colitis, especially in indefinite cases as it brings objectivity in grading. Our study also came to a conclusion that use of bcl-2 for grading dysplasia of ulcerative colitis is not of any significant help.

Morphological and biochemical alterations in the jejunum following iodoacetamide-induced colitis in rats

This study aims to describe the morphological alterations in the small and large intestines as well as the expression of some enterocyte enzymes and carriers in a rat model of iodoacetamide-induced colitis. Biopsies from the large and small intestines were taken at 1, 2, 4, 8, and 16 days postinduction and studied by light microscopy. The expressions of lactase, sucrase, aminopeptidase, and Glut-5 in the jejunum were studied by immunohistochemistry. Gene expressions of enterocyte lactase and sucrase were determined by RT-PCR using specific oligonucleotides. Microscopic examination of the large intestines revealed manifestations concordant with inflammation. Such alterations peaked at 2 days, were maintained to a lesser extent for 4 days, regressed by 8 days, and healed by 16 days. In the jejunum, the expression of lactase, sucrase, and aminopeptidase decreased 2 days after colitis induction, and recovered 2 days later. Similarly, Glut-5 expression decreased transiently with partial recovery by day 8. Compared with sham, gene expression of jejunal brush border enzymes sucrase and lactase showed a 4-fold increase in lactase and a 9-fold increase in sucrase after 4 days. We conclude that colitis can induce significant functional abnormalities in distant noninflamed small bowel regions.

AMACR Immunostaining is Useful in Detecting Dysplastic Epithelium in Barrett's Esophagus, Ulcerative Colitis, and Crohn's Disease

Alpha-methylacyl-CoA racemase (AMACR) catalyzes the racemization of alpha-methyl, branched carboxylic coenzyme A thioesters, and is overexpressed in a variety of neoplasms, such as prostate and colon cancer. The aim of this study was to evaluate AMACR expression in the metaplasia-dysplasia-carcinoma sequence in Barrett's esophagus (BE), ulcerative colitis (UC), and Crohn's disease (CD) and to determine whether its expression can be used to detect dysplastic epithelium in these conditions. One hundred thirty-four routinely processed biopsy and/or resection specimens from 134 patients with BE [M/F ratio: 5.7, mean age: 67 y (36 negative (intestinal metaplasia only), 14 indefinite for dysplasia (IND), 16 low-grade dysplasia (LGD), 32 high-grade dysplasia (HGD), and 36 invasive adenocarcinoma (ACA)] and 74 specimens from 74 patients with inflammatory bowel disease (IBD) [56 with ulcerative colitis, 18 with Crohn's disease, M/F ratio: 1.8, mean age: 55 y (17 negative, 7 IND, 26 LGD, 10 HGD, and 14 ACA)] were immunostained with a monoclonal AMACR antibody (p504S). The degree of cytoplasmic staining in all cases was evaluated in a blinded fashion according to the following grading system: 0, negative (0% cells positive); 1+, 1% to 10% cells positive; 2+, 10% to 50% cells positive; or 3+, >50% cells positive. In patients with BE, AMACR was not expressed in any negative foci (0%) but was significantly increased (P<0.0001) in foci of LGD (38%), HGD (81%), and ACA (72%). Three of 14 (21%) IND foci from 3 BE patients were only focally positive (grade 1: 7%, 2: 14%). However, 1 of these 3 patients had follow-up information available and had developed ACA subsequently. Similarly, in patients with IBD, AMACR was not expressed in any foci considered negative for dysplasia, but was significantly increased (P<0.0001) in foci of LGD (96%), HGD (80%), and ACA (71%). Only 1/7 (14%) IND focus from 1 patient was focally positive (grade 1). The sensitivity for the detection of LGD and HGD in BE and IBD was 38% and 81%, and 96% and 80%, respectively, for the 2 types of disorders. The specificity was 100% for both BE and IBD. AMACR is involved in the neoplastic progression in BE and IBD. The high degree of specificity of AMACR for dysplasia/carcinoma in BE and IBD suggests that it may be useful to detect neoplastic epithelium in these conditions.

Antigen transport and cytoskeletal characteristics of a distinct enterocyte population in inflammatory bowel diseases

Intestinal antigen uptake is enhanced in inflammatory bowel disease. We analyzed transcellular transport routes of antigens in different compartments of normal enterocytes and atypical intestinal epithelial cells called "rapid antigen uptake into the cytosol enterocytes" (RACE cells). These cells constitute a recently described population of enterocyte-derived cells, which are increased in inflammatory bowel disease. Mucosa of freshly resected specimens were incubated with the antigens ovalbumin or horseradish peroxidase. Ultrastructural labeling patterns of differentiation-dependent proteins, the brush-border enzyme sucrase-isomaltase and the cytoskeleton proteins villin and actin, were determined in enterocytes. Apoptosis was investigated biochemically and ultrastructurally by cleavage of caspase-3. Both antigens were transported to late endosomes and to trans-Golgi vesicles of enterocytes in inflammatory bowel disease and control specimens. Quantitative evaluation revealed a significantly increased transepithelial antigen transport in both compartments of RACE relative to normal enterocytes. Labeling densities for sucrase-isomaltase, villin, and actin were decreased in RACE relative to normal enterocytes. Caspase-3 was not increased in RACE cells relative to controls. RACE cells are characterized by increased antigen transport to late endosomes and the trans-Golgi network, a disassembled cytoskeleton and lower concentrations of proteins that are markers of cell differentiation.

High proliferative activity is associated with dysplasia in ulcerative colitis

PURPOSE

Ulcerative colitis is associated with an increased risk of colorectal neoplasia. Markers of proliferation are reported to be valuable in the diagnosis of dysplasia in ulcerative colitis. However, it is not known whether dysplastic change or proliferative change occurs first. Whether abnormal proliferation is present in normal-seeming mucosa in ulcerative colitis was investigated.

METHODS

Eighteen cancer or high-grade dysplasia specimens and 9 low-grade dysplasia specimens from 5 patients and 51 specimens from 31 patients without neoplasia were studied. Immunostaining with anti-Ki 67 antibody was used to evaluate proliferative activity. Labeling index (in the superficial one-half of crypt) was calculated. Crypts with labeling index more than 0.3 were determined to have abnormal proliferation.

RESULTS

The mean +/- standard error of the mean labeling index in specimens negative for dysplasia (0.056+/-0.004) was significantly lower than that in low-grade dysplasia specimens (0.418+/-0.024) and that in high-grade dysplasia specimens (0.503+/-0.027; P < 0.0001). In specimens negative for dysplasia, only 4 (4 cases) of 339 (1.2 percent) crypts had abnormal proliferation, whereas the ratio of crypts with abnormal proliferation was 76 percent (54/71) in low-grade dysplasia and 92.1 percent (35/38) in high-grade dysplasia. The labeling index in background mucosa was 0.139+/-0.009, which was significantly higher than that in specimens negative for dysplasia (P < 0.001). In background mucosa 15.7 percent of crypts showed abnormal proliferation. A follow-up study revealed that two of four cases developed cancer or high-grade dysplasia one and seven years after proliferative abnormality was detected in nondysplastic specimens.

CONCLUSION

Ki-67 immunostaining can be an aid in the diagnosis of dysplasia. High proliferating activity in background mucosa suggests that proliferating activity change precedes dysplasia detected with hematoxylin-and-eosin staining.

Colonic chicken skin mucosa: an endoscopic and histological abnormality adjacent to colonic neoplasms

OBJECTIVES

We recently described an endoscopic finding of pale yellow-speckled mucosa adjacent to colonic neoplasms. This resembled the appearance of chicken skin and was named chicken skin mucosa (CSM). CSM differs from previously reported gastrointestinal xanthelasmas in that this entity always occurs in association with colonic neoplasms. The prevalence, endoscopic characteristics, clinical significance, and possible etiology were investigated.

METHODS

Eight hundred fifty-two consecutive colonoscopies were prospectively evaluated for the presence of CSM associated with either cancer or adenomas > or = 1 cm. Electron microscopy and histopathology using hemotoxylin and eosin, mucicarmine, and oil red O stains were performed. Twelve consecutive colon cancer resection specimens were prospectively examined to determine the presence of histologic CSM.

RESULTS

CSM was adjacent to eight of 10 distal colorectal cancers, one of four proximal colon cancers, 16 of 42 distal adenomas, and three of 44 proximal adenomas. Four of seven resected distal cancers demonstrated histological evidence of CSM. Biopsies of the CSM revealed that lipid-filled macrophages in the lamina propria were responsible for this endoscopic appearance. Electron microscopy showed that the surface epithelial cells had small intestine-like microvilli. CSM was not seen with other colonic conditions and was not associated with the laxative preparation. In four instances, identification of the CSM alerted the endoscopist to the presence of polyps in locations difficult to visualize.

CONCLUSIONS

CSM is an endoscopic entity that occurs as a result of fat accumulation in macrophages in the lamina propria of the mucosa adjacent to colonic neoplasms. Small intestine-like microvilli were present in CSM and the pathophysiological implications remain to be elucidated.

Association between sucrase-isomaltase and p53 expression in colorectal cancer

BACKGROUND

Sucrase-isomaltase (SI) is a tissue-based phenotypic marker that is an independent prognostic factor in colorectal cancer (CRC). DF3 and galectin 3 are two other tissue-based markers that are upregulated during neoplastic transformation. Because p53 mutations are acquired during neoplastic progression, we reasoned that alterations in SI and p53 may be associated despite an apparent lack of biological interaction.

METHODS

Paraffin sections from 183 patients who underwent surgery at New England Deaconess Hospital (NEDH) between 1965 and 1977 were analyzed first by immunohistochemistry (IHC) for the expression of the markers SI, DF3, and galectin 3, which were scored as absent or present. Paraffin sections from a second group of 59 patients who underwent surgery at NEDH between 1985 and 1992 were analyzed by IHC for the expression of p53 as well as SI, DF3, and galectin 3. p53 nuclear staining was scored as absent or present. Previous work has shown that p53 is mutated in all cells with nuclear staining and in 10% of tumors that are unstained.

RESULTS

SI expression was not associated with the expression of either DF3 or galectin 3, and neither DF3 nor galectin 3 were prognostic factors in CRC. None of the phenotypic markers were associated with any of the clinicopathologic variables. However, 21 of 24 p53-positive cases (88%) expressed SI, whereas 15 of 35 p53-negative cases (43%) were also SI negative (p = 0.02, Fisher exact test). p53 expression was not associated with expression of DF3 or galectin 3.

CONCLUSIONS

SI expression and p53 mutation are associated significantly in CRC. Although the mechanism underlying such an association in presently unknown, the association may define a subset of patients with a worse prognosis.

Sucrase-isomaltase is an independent prognostic marker for colorectal carcinoma

PURPOSE

Expression of disaccharidase sucrase-isomaltase (SI) is significantly enhanced during neoplastic transformation of colonic epithelium. Our study was designed to determine whether expression of SI within primary tumors was significantly associated with survival in patients with colorectal carcinoma (CRC).

METHODS

SI expression was analyzed by immunohistochemistry in paraffin sections from 182 Stage I to III CRC that had been resected for cure at the New England Deaconess Hospital between 1965 and 1977. Expression was scored as absent or present in 1 to 50 percent or more than 50 percent of tumor cells. Associations were explored among SI expression, other clinical or pathologic variables, and overall survival. The data set is mature, with 91 (56 percent) patients who had died of CRC at a median follow-up of 96 months.

RESULTS

Fifty-five percent of primary CRC expressed SI. When the multivariate Cox analysis was performed, nodal status, T stage, primary site, grade, and SI expression were independent covariates. SI expression was not associated with the expression of other clinicopathologic variables but increased the risk of death from colorectal carcinoma by 1.83-fold.

DISCUSSION

These results indicate that SI is a prognostic marker for CRC that is independent of stage-related variables in patients who have undergone potentially curative resections.

Sialosyl-Tn antigen: initial report of a new marker of malignant progression in long-standing ulcerative colitis

BACKGROUND & AIMS

Expression of the mucin-associated carbohydrate antigen sialosyl-Tn (STn) correlates with malignant transformation in sporadic colonic neoplasms. The aim of this study was to analyze STn antigen expression in patients with long-standing ulcerative colitis (UC).

METHODS

STn antigen was assessed by immunohistochemistry in archival tissues. Study A was a retrospective chronological case-control study. Serial surveillance colonoscopic biopsy specimens without inflammation or dysplasia were analyzed in 7 patients who developed colon cancer and in 8 controls who did not develop colon cancer. Study B analyzed the anatomic distribution of STn expression in 17 cancer-bearing (case) and 6 cancer-free (control) colectomy specimens from patients with UC. In some colectomy specimens, STn was compared with aneuploidy, which was determined by flow cytometry.

RESULTS

In study A, among the 7 patients with UC who developed cancer, 6 patients (86%) expressed STn in at least one prior nondysplastic surveillance biopsy specimen from the same site. Only 3 of 8 control patients (38%) expressed STn. In study B, STn was expressed in 40 of 82 specimens (49%) from cancer-bearing colons but only 8 of 62 specimens (13%) from cancer-free colons. STn was expressed in most aneuploid areas but was also found in diploid, nondysplastic mucosa.

CONCLUSIONS

STn antigen seems to be a promising marker of cancer risk in patients with UC.

Low incidence of significant dysplasia in a successful endoscopic surveillance program of patients with ulcerative colitis

BACKGROUND/AIMS

Colorectal cancer associated with ulcerative colitis may be preceded by dysplastic changes potentially detectable by repeated endoscopic examinations. The aim of this study was to evaluate the incidence, course, and risk factors for dysplasia in a prospective endoscopic study.

METHODS

One hundred fifty-four patients with ulcerative colitis for 7 or more years' duration were followed from 1976 to 1994 in an endoscopic surveillance program.

RESULTS

Five patients had 10 adenomatous polyps managed by polypectomy. Indefinite dysplasia was found in 16 patients, and none showed progressive dysplasia on follow-up. Low-grade dysplasia was detected in 10 patients; 2 had and 2 progressed to high-grade dysplasia. High-grade dysplasia was found in 7 patients; 4 were concurrent with or just preceded cancer. All 4 cases of cancer were first detected by surveillance, and 3 were successfully treated. Significant risk factors for dysplasia (all grades) and cancer included the extent of disease (P < 0.01), older age at onset of colitis (P = 0.01), and the duration of disease (P < 0.05). The adjusted risk for cancer was significantly increased (P = 0.04).

CONCLUSIONS

Indefinite dysplasia did not predict developing cancer. Low- or high-grade dysplasia was not frequent (8.5%) but was associated with progression to cancer. These can be detected and successfully treated by systematic endoscopic surveillance of patients with chronic (> or = 7 years), extensive (more than the rectosigmoid colon) ulcerative colitis.

Intestinal brush border glycohydrolases: structure, function, and development

The hydrolytic enzymes of the intestinal brush border membrane are essential for the degradation of nutrients to absorbable units. Particularly, the brush border glycohydrolases are responsible for the degradation of di- and oligosaccharides into monosaccharides, and are thus crucial for the energy-intake of humans and other mammals. This review will critically discuss all that is known in the literature about intestinal brush border glycohydrolases. First, we will assess the importance of these enzymes in degradation of dietary carbohydrates. Then, we will closely examine the relevant features of the intestinal epithelium which harbors these glycohydrolases. Each of the glycohydrolytic brush border enzymes will be reviewed with respect to structure, biosynthesis, substrate specificity, hydrolytic mechanism, gene regulation and developmental expression. Finally, intestinal disorders will be discussed that affect the expression of the brush border glycohydrolases. The clinical consequences of these enzyme deficiency disorders will be discussed. Concomitantly, these disorders may provide us with important details regarding the functions and gene expression of these enzymes under specific (pathogenic) circumstances.

Prospective evaluation of early morphological changes in pelvic ileal pouches

BACKGROUND/AIMS

Little is known about the evolution of morphological changes in pelvic ileal-pouch mucosa. This study evaluates prospectively the sequence of early morphological, histochemical, and phenotypic features in pouch mucosal biopsy specimens.

METHODS

Twenty-two patients with pelvic ileal pouches constructed after total colectomy for chronic ulcerative colitis had biopsies performed at the time of ileostomy closure and after 6 weeks and 6 months of pouch function and were evaluated to assess the type and degree of inflammation, villus atrophy, Paneth's cell hyperplasia, mucin histochemical changes, the mucosal proliferative activity using the murine monoclonal antibody 1 (MIB-1), and the expression of the enzyme sucrase-isomaltase.

RESULTS

Early changes (6 weeks) were characterized by neutrophilic and eosinophilic inflammation, mild villus atrophy, Paneth's cell hyperplasia, a partial transition to colonic mucin phenotype, and an increased MIB-1 proliferation index. These features remained relatively stable after 6 months, except for a greater degree of mononuclear infiltration, a progressive increase in the degree of eosinophilic inflammation and a new higher steady state level of crypt epithelial kinetics. Expression of sucrase-isomaltase remained stable.

CONCLUSIONS

Pelvic ileal pouches develop inflammatory, phenotypic, and kinetic changes early in the course of function but have only a limited potential for colonic type metaplasia. The persistence of these changes is evidence in support of an adaptive response to a new luminal environment.

Localization of tumor-associated glycoprotein DF3 in normal, inflammatory, and neoplastic lesions of the colon

BACKGROUND

The expression of DF3 was assessed by a monoclonal antibody in normal, inflammatory, and neoplastic conditions in the large bowel.

METHODS

Using immunohistochemistry, expression was examined in formalin-fixed paraffin-embedded biopsy and resection samples of 19 normal colonic mucosal specimens, 49 inflammatory lesions, 34 adenomas, and 38 primary colonic adenocarcinomas. In addition, Western blots of normal colonic mucosa and adenocarcinoma were examined.

RESULTS

DF3 expression was detected in 84% of the adenocarcinomas with coarse membrane staining, intense positivity of luminal secretions, and focal cytoplasmic and intracytoplasmic vacuole staining. Nine of 32 areas of transitional mucosa revealed reactivity along apical membranes in crypt cells. Five adenomas containing carcinoma revealed DF3 positivity in the malignant areas only, whereas the remaining 29 were negative. Staining was membrane, luminal, and intracytoplasmic. Two examples of active ulcerative colitis revealed focal reactivity along the apical membrane of crypt cells. No other areas of staining were noted, including 12 cases containing dysplasia. Four of 10 other inflammatory lesions also revealed similar membrane reactivity in crypt cells. Normal colonic mucosa was nonreactive. Examples of normal colonic mucosa were negative for DF3 by Western blot analysis, whereas two carcinoma samples that reacted immunohistochemically were positive.

CONCLUSIONS

DF3 is not detectable in normal colonic tissues. It is expressed focally and predominantly along the apical membrane of crypt cells in some inflammatory lesions and in the transitional mucosa of primary adenocarcinomas. Most adenocarcinomas of the colon and adenomas with foci of invasive carcinoma demonstrate reactivity in the cytoplasm and luminal secretions.

Sucrase-isomaltase gene expression in Barrett's esophagus and adenocarcinoma

BACKGROUND

Specialized Barrett's esophageal mucosa, characterized by incomplete intestinal metaplasia of the esophageal mucosa, is associated with the development of adenocarcinoma. Although the intestinal disaccharidase sucrase-isomaltase (SI) has been shown in incomplete intestinal metaplasia of the stomach, it is commonly believed that Barrett's mucosa does not express SI based on the lack of enzymatic activity. This study was undertaken to determine whether the SI gene is expressed in Barrett's epithelium and its associated adenocarcinoma at the level of messenger RNA (mRNA) and protein.

METHODS

Reverse transcription polymerase chain reaction was used to determine the presence of SI mRNA in Barrett's esophagus and esophageal adenocarcinomas. Cellular localization of SI protein was determined by immunohistochemistry.

RESULTS

SI mRNA was identified in 76% of Barrett's epithelium and 82% of esophageal adenocarcinomas. The transcriptional initiation site for SI in these tissues was identical to that of the small intestine. Immunohistochemical localization showed that SI was directed to the apical membrane in Barrett's epithelium in contrast to a more diffuse cytoplasmic pattern in esophageal adenocarcinomas.

CONCLUSIONS

Columnar cells of specialized Barrett's epithelium express SI and are, therefore, phenotypically similar to those in incomplete intestinal metaplasia of the stomach with respect to intestinal gene expression.