ABSTRACT
AIM: To investigate whether deficiency of expression of cytochrome c oxidase I (CcOI) in colonic crypts is associated with colon cancer. METHODS: The pattern and level of expression of CcOI in non-neoplastic colonic crypts, and in dysplastic tissues, was assessed using standard immunohistochemical methods. Biopsies were obtained from individuals undergoing colonoscopies for screening purposes or for a medically indicated reason. Tissue samples were also obtained from surgical colonic resections. Samples from resections were taken from colonic mucosa 1 and 10 cm from tumors and from the tumors themselves. Samples were evaluated for frequency of crypts with reduced or absent expression of CcOI. In most crypts the loss was apparent throughout the entire crypt, while in a small minority the loss was segmental. The strong immunoreactivity using this monoclonal antibody makes the scoring unambiguous. The percent of crypts with reduced or absent expression of CcOI or (infrequent) segmented loss of expression was then calculated. Data analyses were performed using SPSS statistical package 17.0. RESULTS: The average frequency of CcOI deficient crypts (CcOI-DC) is low in individuals between 20 and 39 years of age, with 0.48% ± 0.40% CcOI-DC for women and 1.80% ± 0.35% for men. CcOI-DC increases after age 40 years, so that between the ages of 40 and 44 years the average frequency of CcOI-DC goes up to 5.89% ± 0.84% in women and 2.15% ± 1.27% in men. By 80-84 years of age, the average frequency of CcOI-DC goes up in women to 15.77% ± 0.97% and in men to 22.6% ± 0.65%. The increases in CcOI-DC from ages 40-44 years compared to 80-84 years in women and men are significantly different with P < 0.01. For women over age 60 years, deficiency of CcOI expression is greater in those women who have had a cancer in their colon. The frequency of CcOI-DC, measured in men, increased in tissues adjacent to colon cancer, being 4.03% ± 0.27% in individuals free of neoplasia in the age range 55-64 years and 14.13% ± 0.35% in resected histologically normal tissue of men with cancer in the same age range, P < 0.001. Similar significant differences were noted in older age ranges. The frequency of CcOI-DC crypts in the cecum and sigmoid colon of an individual are significantly correlated, with an R(2) = 0.414 for women and R(2) = 0.528 for men, P < 0.001. This suggests that the factors determining the level of CcOI deficiency act throughout the colon. Most defective crypts are in clusters of two or more, a likely consequence of crypt fission. In the non-neoplastic margins of cancers, crypts are frequently deficient for CcOI, and such crypts may appear in large clusters, some containing more than 100 deficient crypts. CcOI deficiency is also apparent in colon cancers and sometimes involves a large section of the tumor. Overall, CcOI deficient cells can be visualized in segments of crypts, in whole crypts that increase in frequency with age, in crypts undergoing fission, in clusters of crypts where the clusters increase in size with age, in increased frequency near tumors, in large clusters in the intimate margins of tumors, and in the tumors themselves. There is no clear dividing line between early stages that can be considered aspects of aging and later stages that can be considered aspects of the progression to cancer. This ambiguity may reflect a rather general situation leading to adult cancer where the early stages of cellular change appear to be relatively innocuous features of the aging process but over decades may evolve into malignancy. CONCLUSION: CcOI deficient crypts increase in frequency with age, and clusters of deficient crypts are associated with, and may give rise to, colon cancer.
ABSTRACT
BACKGROUND: A high-fat diet is a risk factor for the development of inflammatory bowel disease (IBD) in humans. Deoxycholate (DOC) is increased in the colonic contents in response to a high-fat diet. Thus, an elevated level of DOC in the colonic lumen may play a role in the natural course of development of IBD. METHODS: Wild-type B6.129 mice were fed an AIN-93G diet, either supplemented with 0.2% DOC or unsupplemented and sacrificed at 1 week, 1 month, 3 months, 4 months, and 8 months. Colon samples were assessed by histopathological, immunohistochemical, and cDNA microarray analyses. RESULTS: Mice fed the DOC-supplemented diet developed focal areas of colonic inflammation associated with increases in angiogenesis, nitrosative stress, DNA/RNA damage, and proliferation. Genes that play a central role in inflammation and angiogenesis and other related processes such as epithelial barrier function, oxidative stress, apoptosis, cell proliferation/cell cycle/DNA repair, membrane transport, and the ubiquitin-proteasome pathway showed altered expression in the DOC-fed mice compared with the control mice. Changes in expression of individual genes (increases or reductions) correlated over time. These changes were greatest 1 month after the start of DOC feeding. CONCLUSIONS: The results suggest that exposure of the colonic mucosa to DOC may be a key etiologic factor in IBD. The DOC-fed mouse model may reflect the natural course of development of colitis/IBD in humans, and thus may be useful for determining new preventive strategies and lifestyle changes in affected individuals.
