Early precancerous modifications in the mucus of human and rat distal colon: a comparative immunohistologic study

Early detection of colonic dysplasia by magnetic resonance molecular imaging with a contrast agent raised against the colon cancer marker MUC5AC

Human gastric mucin MUC5AC is secreted in the colonic mucus of cancer patients and is a specific marker of precancerous lesions called aberrant crypt foci. Using MUC5AC as a specific marker can improve sensitivity in the detection of early colorectal cancer. Here we demonstrated that the accumulation of MUC5AC in xenograft and mouse stomach can be detected by magnetic resonance imaging (MRI). We used ultrasmall particles of iron oxide (USPIOs) conjugated with disulfide constrained heptapeptide that were identified using a screening phage display. To accomplish this, we employed positive selection of the phage display library on MUC5AC purified from fresh human colonic adenomas in combination with negative selection of the phage library on purified human MUC2, which is predominantly found in normal colorectal tissues. This conjugate was tested on human colorectal cancer cell lines that were either able or unable to secrete MUC5AC, both in vitro and in vivo. MUC5AC-USPIO contrast agent and USPIOs alone were not detected in cell lines unable to secrete MUC5AC. A combination of MRI and microscopy studies was performed to detect a specific accumulation of the contrast agent in vivo. Thus, the MUC5AC contrast agent enabled non-invasive detection of precancerous lesions and colorectal cancer, highlighting its potential use in diagnostics, in the early detection of colorectal cancer recurrences after treatment and in mechanistic studies implicating MUC5AC. Copyright © 2016 John Wiley & Sons, Ltd.

Mapping of SOMU1 and M1 Epitopes on the Apomucin Encoded by the 5′ End of the MUC5AC Gene

We have developed 11 monoclonal antibodies (MAbs) against human gastric mucin, (1-13M1, 2-11M1, 2-12M1, 9-13M1, 58M1, 19M1, 21M1, 45M1, 463M, 589M, 62M1), which specifically stained by immunohistochemisty both the human gastric surface mucosa and colon adenoma. Among them, five (19M1, 21M1, 463M, 589M, 62M1) immunoreacted with the peptide encoded by the 3' region of the MUC5AC gene (Nollet et al: Int J Cancer 2002;99:336-343). In this study, we identified in the 5' region of this gene the nucleotide fragments encoding peptides immunoreacting with three other anti-M1 MAbs (1-13M1, 2-11M1 and 9-13M1), as well as the SOMU1 MAb (Sotozono et al: J Immunol Methods 1996;192:187-196). 1-13M1 MAb immunoreacts with peptides, including the Cys 2 and Cys 4 domains. The SOMU1 MAb recognized the Cys 5 domain, and the MAbs 2-11M1 and 9-13M1 the globular D1/D2 and D3 domains, respectively. Using serial sections of the mucosae adjacent to colon adenocarcinomas and colon adenomas, we observed that the anti-M1 and anti-SOMU1 MAbs displayed the same immunostaining patterns. The three anti-M1 MAbs (2-12M1, 58M1, and 45M1) did not react with the products of the MUC5AC gene tested until now. The MUC5AC apomucin is now well characterized by MAbs immunoreacting against seven different epitopes belonging to the different main cystein globular domains of this macromolecule. Such antibodies are useful tools for studying the biosynthesis, polymerization, and degradation of mucin.

Inhibition of tumor progression and neoangiogenesis using cyclic RGD-peptides in a chemically induced colon carcinoma in rats

Integrins are cell surface molecules that mediate cell adhesion, but are also important regulators of tumor cell interactions with their microenvironment, tumor cell survival and growth. In addition, the alpha(v)beta3-integrins appear to be critical for microvessel formation in tumor-induced neoangiogenesis. The present study is the first to investigate the effects of therapeutic alpha(v)beta3-integrin inhibition in a chemically induced tumor model that largely resembles human colon carcinomas. Tumor induction was performed in 47 male Sprague-Dawley rats using 1,2 dimethylhydrazin (21 mg/kg) twice a week. After 20 weeks of tumor induction, 100% of the animals developed adenocarcinomas with a median of 13.5 macroscopic tumor nodules (range 12-17), but no distant metastases. During further tumor induction for an additional 10 weeks, rats were treated three times/week with (a) 15 mg/kg RGDfV-peptide that can block vitronectin and fibronectin receptors; (b) an equimolar amount of an ineffective cyclic control peptide; or (c) with equimolar amounts of a linear RGDS-peptide. At the end of this treatment period, rats were sacrificed, and tumor load was quantified macroscopically and confirmed by histological examination. For investigation of the involvement of tumor-induced neoangiogenesis microvessel, density was determined using CD31-immunostaining. After 30 weeks, control animals (group B) had 5-18 tumors (median 14.5). If rats were treated with RGDfV-peptide (group A), the number of tumor nodules was significantly reduced (P < 0.005) to a median of seven macroscopic tumors (range 2-10 tumors), which also represented a significant reduction (P < 0.005) compared with prior to treatment. Application of noncylic RGDS-peptides (group C) did not affect the number of tumor nodules (median 18; range 10-30 tumors). The diameters of tumor nodules were comparable (3.2-6.1 mm) in animals of all groups. In addition, microvessel density was significantly (P < 0.05) reduced in tumors in group A compared to control rats. The major side effect in the treatment group was increased susceptibility to respiratory infections. Our results demonstrate that alpha(v)beta3-integrin-receptor inhibition appears to be a therapeutic strategy for colorectal cancer. In our therapeutic model, late onset of treatment with integrin-blocking peptides resulted in an inhibition of tumor growth and a reduced tumor load which appeared to be mediated, at least in part, by inhibition of neoangiogenesis.

The clinical and biological significance of the transitional mucosa adjacent to colorectal cancer

The underlying nature of the transitional mucosa adjacent to colorectal cancer is defined and the evidence for and against the statement that this transitional mucosa involves primary premalignant change presented in this article. An association between mucin histochemical changes at the margins of resection and a poorer clinical outcome of patients has been recognized in patients with colorectal cancer after surgery. The retained transitional mucosa at the margins of resection appears to correlate with tumor recurrence and a poorer survival in patients who have undergone radical resection. It is considered that the transitional mucosa adjacent to colorectal cancer and its presence at the margins of resection may be an important prognostic marker for patients with large bowel cancer following radical resection.

Mucin immunohistochemistry of the columnar epithelium of the oesophagus (Barrett's oesophagus)

Columnar cell lined lower oesophagus (CELLO), often considered to be a precancerous lesion, is characterized by a glandular mucosa with a predominance of sulphomucins in the specialized epithelium. This histochemical abnormality can be correlated with abnormal differentiation which may also be studied by anti-mucus antibodies (anti-M1, anti-M3, anti-SIMA, anti-LIMA). The purpose of this prospective study is to define the mucin profile in a large population of CELLO by immunohistochemistry and to compare it with the results of histochemistry. Biopsies of 79 patients with reflux oesophagitis were included. Thirty-eight had CELLO and 41 had a histologically normal cardia. Six surgical specimens of oesophageal adenocarcinomas were also included. The histochemical methods confirmed the preponderance (57.9%) of type III intestinal metaplasia (IM) found in 57.9% of cases. The immunohistochemical methods showed a similar antigenic profile of type II and III IM with positivity of anti-SIMA and anti-M3 antibodies in the goblet cells, and positivity of anti-LIMA antibodies in both the goblet and intermediate cells of the specialized epithelium. The mucus secreting cells of the oesophageal adenocarcinomas had the same immunohistochemical profile. These results are similar to those of Filipe et al. in type II and III IM surrounding gastric adenocarcinomas. Immunohistochemical methods allow us to subdivide type II and type III IM into 2 subgroups according to the positivity or negativity of the anti-LIMA antibodies in the intermediate cells. Among the 41 normal cardias in patients with reflux oesophagitis, 10 contain sulphomucin secreting cells positive with anti-LIMA antibodies. We suggest that this anti-LIMA positivity may be a step preceding type III IM in specialized epithelium.

Rat colonic carcinogenesis after ureterosigmoidostomy: pathogenesis and immunohistological study

A group of 44 rats underwent the equivalent of a ureterosigmoidostomy (US), while a second group of 18 rats underwent a pediculated graft (PG) of urothelial tissue in the sigmoid wall. Histological lesions were observed in the colon near the bladder colon junction in US rats exclusively. These lesions included dysplasias (5/23), cystic glands (4/23) and 10 neoplasms (9/23), three of which were adenomas, showing elements of juvenile polyp and tubular adenoma in one case. The seven other tumors showed typical histological features of colonic adenocarcinomas, but no frank evidence of parietal tumoral invasion was observed and their cancerous nature was questionable. It is probably a true carcinogenesis since we induced the same histological changes as those in the mucosae adjacent to colonic adenocarcinomas after human US surgery. Moreover, by immunoperoxidase using antibodies against mucus associated antigens (M1 and M3C antigens) we demonstrated that US rat carcinogenesis differs from dimethylhydrazine (DMH) rat carcinogenesis. Furthermore, our results suggest that urine may be an important factor in inducing this type of US carcinogenesis.