Intestinal mucin antigens in ulcerative colitis and their relationship with malignancy

Emerging avenues linking inflammation and cancer

The role of inflammation in carcinogenesis has been extensively investigated and well documented. Many biochemical processes that are altered during chronic inflammation have been implicated in tumorigenesis. These include shifting cellular redox balance toward oxidative stress; induction of genomic instability; increased DNA damage; stimulation of cell proliferation, metastasis, and angiogenesis; deregulation of cellular epigenetic control of gene expression; and inappropriate epithelial-to-mesenchymal transition. A wide array of proinflammatory cytokines, prostaglandins, nitric oxide, and matricellular proteins are closely involved in premalignant and malignant conversion of cells in a background of chronic inflammation. Inappropriate transcription of genes encoding inflammatory mediators, survival factors, and angiogenic and metastatic proteins is the key molecular event in linking inflammation and cancer. Aberrant cell signaling pathways comprising various kinases and their downstream transcription factors have been identified as the major contributors in abnormal gene expression associated with inflammation-driven carcinogenesis. The posttranscriptional regulation of gene expression by microRNAs also provides the molecular basis for linking inflammation to cancer. This review highlights the multifaceted role of inflammation in carcinogenesis in the context of altered cellular redox signaling.

Aberrant gastric apomucin expression in ulcerative colitis and associated neoplasia

AIM

To evaluated the presence of gastric metaplasia in colonic mucosa of patients with ulcerative colitis and its relationship with dysplasia/neoplasia.

MATERIAL AND METHODS

Ninety patients with UC were selected. The duration and the extent of disease were registered in all the cases. Biopsies were histologically and immunohistochemically assessed. Crypt distortion, goblet cell depletion, Paneth cell metaplasia and inflammatory activity were graded, as well as dysplasia and invasive neoplasia (absent or present). Monoclonal antibodies against the gastric apomucins MUC5AC (foveolar) and MUC6 (mucopeptic) were used.

RESULTS

Neoplasia was observed in 16 patients, 8 non-invasive (dysplasia) and 8 invasive (adenocarcinoma). MUC5AC and MUC6 were detected in 63 and 16 out the 90 cases, 70.0% and 17.8%, respectively. The staining was patchy for both antibodies, affecting groups of cells more often than isolated cells. The presence of MUC5AC correlated positively with inflammatory activity and goblet cell depletion (R=0.231, p=0.03 and R=0.211, p=0.048, respectively). The expression of MUC6 correlated positively with age (R=0.297, p=0.005), duration of disease (R=0.287, p=0.008), extent of disease (R=0.342, p=0.001), crypt distortion (R=0.276, p=0.01) and the presence of neoplasia (R=0.483, p<0.00). There was no correlation between Paneth cell metaplasia and apomucin expression.

CONCLUSIONS

Our study demonstrates the aberrant expression of gastric apomucins in UC and suggests that MUC5AC is associated with inflammation while MUC6 is related to the presence of neoplasia. The demonstration of metaplastic cell lineages preceding dysplasia supports the biological link between inflammation and neoplasia, MUC6 emerging as a putative biomarker of dysplasia in ulcerative colitis patients.

Proton pump inhibitor co-therapy normalizes the increased cell turnover of the gastric mucosa both in NSAID and selective COX-2 users

Proton pump inhibitor (PPI) co-therapy is considered the best strategy in preventing gastrointestinal complications during non-steroidal anti-inflammatory drug (NSAID) treatment, but there is limited information available on its effect on gastric mucosal cell kinetics. To evaluate the effect of PPI co-therapy on gastric mucosa we investigated epithelial cell proliferation, apoptosis, epithelial growth factor receptor (EGFR) and p53 expression in patients on chronic non-selective NSAID or cyclooxygenase-2 selective inhibitor (COX-2) treatment. Gastric biopsies of the antrum were taken from 10-10 patients on chronic NSAID and COX-2, therapy prior and after 6 months PPI co-therapy, and 10 controls without any treatment. Cell proliferation, apoptosis, EGFR and p53 expression were measured by immunohistochemistry. At least 600 glandular epithel cells were encountered and results were expressed as % of total cells counted. We found increased cell proliferation in patients on chronic COX-2 but not on NSAID therapy. Patients on either NSAID or COX-2 therapy had an increased p53 and decreased EGFR expression. PPI therapy reversed not only the increased cell proliferation and p53 expression, but also the suppressed EGFR expression when administered as co-therapy. The fewer gastrointestinal side effects observed during chronic COX-2 therapy may partially be the result of the higher cell proliferation. This effect is not mediated by the EGFR pathway. PPI co-therapy normalizes the disturbed cell kinetics irrespective of NSAID treatment used.

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.

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.

Oral congenital dermoid cyst in the floor of the mouth of a newborn. The significance of gastrointestinal-type epithelium

A case of congenital dermoid cyst in the floor of the mouth in a newborn is presented. The presence of microcyst formation with intestinal-type epithelial lining and mucin histochemistry are discussed.

The adenoma-carcinoma sequence in the colorectum--early appearance of a hierarchy of small intestinal mucin antigen (SIMA) epitopes and correlation with malignant potential

The colorectal adenoma-carcinoma sequence was examined in relation to the ectopic expression of the oncofoetal Small Intestinal Mucin Antigen (SIMA), to the development of morphologic changes in the adenoma and perineoplastic mucosa and to indices of malignant potential. Four anti-SIMA MAbs, which define a novel hierarchy of SIMA epitopes in the normal small intestine and adjacent to colorectal cancers, were used in a retrospective immunohistochemical study of Familial Adenomatous Polyposis (FAP, n = 183) and non-familial (n = 44) adenomas. Inappropriate expression of SIMA epitopes was first detected in mucosa adjacent to minute microadenomas larger than three glands, and with increase in size, in increasing amounts within adenomas themselves, but not with microadenomas smaller than three glands or regions of flat mucosa free of adenomas. SIMA epitope expressed in mucosa adjacent to adenomas preceded changes in perineoplastic morphology, which progressed with adenoma growth to resemble transitional mucosa (TM) adjacent to cancers. Thus, the onset of both SIMA expression and morphological changes in TM were consistent with reactive rather than pre-existing field change phenomena. The previously reported hierarchy of four SIMA epitopes (5C5, 3D4, 4D3, 6C5) was also consistently observed in the adenoma-carcinoma sequence, and applied to (i) the order of epitope detection, (ii) the number of positive adenomas and (iii) extent of staining; (iv) the height in the crypt and (v) distance from the adenoma to which epitopes were expressed in perineoplastic mucosa. These observations are consistent with a progression of changes in mucin composition with adenoma development. The percentage of positive adenomas and reactivity scores for each anti-SIMA MAb correlated with increasing adenoma size, degree of dysplasia and growth pattern. SIMA expression appears to predate the earliest reported oncogene and tumour suppressor gene changes, was persistent and increased throughout adenoma development. SIMA epitopes are thus markers of very early neoplastic change, whose expression correlates with malignant potential and may contribute to the accumulation of changes necessary for tumourigenesis.

A combination of cytological and architectural morphometry in assessing regenerative hyperplasia and dysplasia in ulcerative colitis

Morphometry and stereology were used to assess the cytological and architectural characteristics of regenerative and dysplastic colorectal mucosal abnormalities in ulcerative colitis. Reproducibility of measurements was assessed and found to be good, confirming the objective and reproducible nature of morphometric analysis. Discriminant analysis between the morphometric features of regenerative mucosal change and low-grade dysplasia revealed the significant cytological and architectural variables from which a cytological and architectural score were derived. The architectural score was capable of classifying all of the cases into their correct diagnostic category, although a combination of the two scores provided better separation of cases. Probability density analysis was carried out so that probabilities of group membership could be allocated to cases, given their cytological and architectural scores. Discriminant analysis was also applied to low- and high-grade dysplasia. Important cytological and architectural variables were identified and used separately to derive scoring systems. In combination, the dual scoring of lesions was capable of separating low- from high-grade dysplasia, although overlap was still evident. Again, probability density analysis allowed the allocation of cases into one or other category, although a closer examination showed that such a rule could not successfully classify a new set of low- and high-grade dysplasia cases. Quantitative histological analysis of mucosal abnormalities is shown to be of use in the objective diagnosis of reactive and dysplastic change in patients with ulcerative colitis. The use of simple scoring systems and probability based allocation of cases promotes the future role of morphometric techniques in the diagnostic laboratory.