Is mucin a determinant of peritoneal dissemination of gastrointestinal cancer? Analysis of mucin depletion in two preclinical models

Background. Mucinous gastrointestinal cancers may indicate a higher propensity for widespread peritoneal seeding than their non-mucinous counterparts. We hypothesized that mucin content of gastrointestinal cancer cells and tumors is an indicator of cell viability and a determinant of the peritoneal tumor burden and tested our hypothesis in relevant experimental models. Methods. MKN45 and LS174T models of human gastrointestinal cancer were treated with known mucin-depleting agents in vitro and in vivo, their mucin production was evaluated with Western blot immunohistochemistry, PAS staining and ELISA, and its correlation with cell viability and peritoneal tumor burden was analyzed. Results. A relationship was found between the viability of cancer cells and their mucin levels in vitro. In agreement, when treated animal models were categorized into low- and high-burden groups (based on the weight and number of the peritoneal nodules), tumoral mucin levels were found to be significantly higher in the latter group. Conclusions. Tumoral mucin is apparently among the factors that dictate the pattern and extent of the peritoneal spread of gastrointestinal cancer, where it allows for enhanced dissemination and redistribution. If further tested and validated, our hypothesis could lay the basis for the development of novel mucin-targeted strategies (AU)

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Mucosal protective agents prevent exacerbation of NSAID-induced small intestinal lesions caused by antisecretory drugs in rats.

Antisecretory drugs such as histamine H2-receptor antagonists and proton pump inhibitors are commonly used for the treatment of upper gastrointestinal mucosal lesions induced by nonsteroidal anti-inflammatory drugs (NSAIDs). However, it has recently been reported that these drugs exacerbate NSAID-induced small intestinal lesions in rats. Unfortunately, there are few effective agents for the treatment of this complication. We examined the effects of mucosal protective agents (MPAs) (misoprostol, irsogladine, and rebamipide) and mucin of porcine stomach on diclofenac-induced intestinal lesions and the exacerbation of the lesions by ranitidine or omeprazole. The effects of the drugs on intestinal motility and mucus distribution/content were also examined. Male Wistar rats (180-220 g) were used. Each drug was administered orally under fed conditions. Diclofenac (1-10 mg/kg) produced multiple lesions in the small intestine dose-dependently. Both ranitidine (30 mg/kg) and omeprazole (100 mg/kg) significantly increased the intestinal lesions induced by low doses (3 and 6 mg/kg) of diclofenac. Misoprostol (0.03-0.3 mg/kg), irsogladine (3-30 mg/kg), and rebamipide (30-300 mg/kg), as well as mucin (30-300 mg/kg) inhibited the formation of intestinal lesions caused by a high dose (10 mg/kg) of diclofenac alone and prevented the exacerbation of diclofenac-induced lesions by antisecretory drugs. Diclofenac (10 mg/kg) markedly increased the intestinal motility and decreased the mucosal mucus, and the decrease of mucus was significantly inhibited by the MPAs. These results indicate the usefulness of the MPAs for the treatment of intestinal lesions induced by NSAIDs alone or by coadministration with antisecretory drugs, and suggest that mucus plays an important role in the protection of intestinal mucosa by the MPAs.

Oral administration of swine gastric mucin alters levels of serum and urine nitric oxide, and lipid metabolism in mice.

Mice were fed with swine gastric mucin in a basal diet for 5 weeks. In 5 week-old mice, a 2% mucin diet significantly decreased nitric oxide levels of serum and liver. Reduction of serum total cholesterol and triglyceride and increase of HDL-cholesterol level were also significant with the mucin diet. In 14 month-old mice, the mucin diet was less effective.