Inhibition of mucosal lipid hyperoxidation by green tea extract in 1,2-dimethylhydrazine-induced rat colonic carcinogenesis.

Phosphatidylcholine hydroperoxide (PCOOH) measured using a chemiluminescence detector to examine colonic mucosal lipid hyperoxidation increased after injection of 1,2-dimethylhydrazine and green tea extract (GTE), which we previously showed inhibited carcinogenesis and oxidative DNA damage in the gastrointestinal tract. Therefore, the hyperoxidation of membrane phospholipids reflected well the degree of DNA damage and carcinogenic alteration, and may be a useful intermediate biomarker for initiation of carcinogenesis.

Inhibition of 1,2-dimethylhydrazine-induced oxidative DNA damage by green tea extract in rat.

Following subcutaneous injection of 1,2-dimethylhydrazine (DMH), which is carcinogenic to rat colon and liver, to Sprague-Dawley rats, a significant increase of 8-hydroxydeoxyguanosine (8-OHdG) was observed in the DNA of colonic mucosa and liver. The 8-OHdG formation reached the maximal level at about 24 h after the DMII injection. On the other hand, no increase of 8-OHdG was observed in the DNA of the kidney. Drinking green tea extract (GTE) for ten days prior to the DMH injection significantly inhibited the formation of 8-OHdG in the colon. These findings demonstrate that DMH causes oxidative damage to the DNA of its target organ, and that GTE protects colonic mucosa from this oxidative damage.

Immunohistochemical staining and activity of ornithine decarboxylase in colorectal cancer.

Using a new anti-human ornithine decarboxylase (anti-hODC) monoclonal antibody, the relationship between the immunoreactivity of ODC and its activity was analyzed in 21 human colorectal cancer tissues, 42 adjacent non-tumorous mucosa specimens, and 10 normal rectal mucosa samples from frozen sections and paraffin-embedded samples. A statistical significant correlation was found between the antibody reaction and the enzymic activity (P < 0.01). The immunohistochemical staining for ODC provides a new and simplified procedure for studying the activity of ODC as compared to previous methods using radioisotopes. It offers the advantages of retrospectively determining the amount of ODC in samples previously embedded in paraffin.

Inhibition of N-methyl-N'-nitro-N-nitrosoguanidine-induced carcinogenesis by (-)-epigallocatechin gallate in the rat glandular stomach.

Recently, an epidemiological study showed a lower risk of gastric cancer among people who consume a large amount of green tea. (-)-Epigallocatechin gallate (EGCG), one of the main constituents of green tea, inhibited tumor promotion by teleocidin in a two-stage carcinogenesis experiment with the use of mouse skin. The inhibitory effect of EGCG on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis of the glandular stomach in rats was examined. The percentage of tumor-bearing rats in the group treated with MNNG plus EGCG was 31%, compared to 62% in the MNNG group. The difference was statistically significant (P < 0.05). To assess the effect of p.o. administration of EGCG, the gastric mucosal cellular kinetics was examined with the use of the bromodeoxyuridine labeling index, ornithine decarboxylase activity, and tissue polyamine levels. The labeling index of the EGCG treatment group decreased significantly (P < 0.05) compared to the EGCG plus MNNG treatment group. The ornithine decarboxylase activity and tissue spermidine levels were also decreased. On the other hand, the tissue putrescine and spermine levels were partly increased. These findings suggest that EGCG inhibits the cellular kinetics of the gastric mucosa during the promotion stage of MNNG-induced gastric carcinogenesis. EGCG may be useful in preventing gastric carcinogenesis. Moreover, EGCG may be applied clinically without any harmful effects and at a low cost.

Risk analysis of carcinogenesis in the remnant stomach with measurement of ornithine decarboxylase activity.

Gastric ornithine decarboxylase (ODC) activity was measured as a biomarker of tumor-promoting activity in the remnant stomach of rats and humans. Gastrectomy of Wistar rats utilizing the Billroth I method caused a significantly high induction of ODC, and use of the Billroth II method caused a significantly higher induction of ODC than the Billroth I method. In humans, ODC activity of remnant gastric cancer tissue, normal-appearing mucosa of remnant gastric cancer patient, and remnant gastric mucosa without cancer after the Billroth II method were significantly higher than that of normal gastric mucosa without gastrectomy. ODC activity of remnant gastric mucosa without cancer after the Billroth II method was significantly higher than that after the Billroth I method. Risk of carcinogenesis was high in the remnant stomach, especially after the Billroth II method.

Inhibitory effects of fucoxanthin, a natural carotenoid, on N-ethyl-N'-nitro-N-nitrosoguanidine-induced mouse duodenal carcinogenesis.

Fucoxanthin was shown to inhibit chemical carcinogenesis. Fucoxanthin is a natural carotenoid prepared from brown algae which is an ingredient used daily in Japanese food. In this study, all mice were given 0.01% N-ethyl-N'-nitro-N-nitrosoguanidine in their drinking water for 4 weeks. This was followed by 0.005% fucoxanthin in dimethylsulfoxide or the vehicle alone in the drinking water. In the 16-week fucoxanthin-treated group both the percentage of tumor-bearing mice and the average number of tumors per mouse were significantly lower than those of the control group. The results indicate that fucoxanthin inhibited duodenal carcinogenesis induced by N-ethyl-N'-nitro-N-nitrosoguanidine in mice.

Balloon dilatation for anastomotic stricture after upper gastro-intestinal surgery.

We report our study on the correlation between the types of anastomosis and the incidence of anastomotic stricture formation in the upper gastro-intestinal tract. Our experience with balloon dilatation is also reported. We examined the incidence of stricture formation among patients who had an anastomosis between the esophagus and stomach following subtotal esophagectomy for esophageal cancer, and esophagojejunostomy following proximal or total gastrectomy for gastric cancer in the past 17 years. Among 283 patients undergoing esophagojejunostomy, 7 cases of stricture (excluding 3 cases of cancer recurrence) were observed (conventional anastomosis 1.8%; stapling anastomosis 4.6%). There were 17 cases of stricture among 56 patients who had anastomosis between the esophagus and stomach following subtotal esophagectomy (conventional anastomosis 28.6%; stapling anastomosis 50.0%). One month or more after the operation, the diameter of the esophagojejunostomy was estimated using a barium study. The mean diameter of the anastomosis using the stapling method was 11.9 +/- 2.9 mm, whereas the mean diameter of serosubmucosal single layer hand-sewn anastomosis (Jourdan's) was 19.8 +/- 2.2 mm, and that of vertical mattress hand-sewn anastomosis was 19.0 +/- 2.0 mm. Balloon dilatation was used in 29 patients with anastomotic stricture of the upper gastro-intestinal tract (esophageal cancer, 19 patients, gastric cancer, 10 patients). With repeated dilatation, we were able to obtain satisfactory efficacy for benign strictures and there were no severe complications. We believe that balloon dilatation is an easy, safe and effective therapy for anastomotic stricture of the upper gastro-intestinal tract.

Palm carotene inhibits tumor-promoting activity of bile acids and intestinal carcinogenesis.

The effects of palm carotene on chemical carcinogenesis was studied. Palm carotene suppressed mouse epidermal ornithine decarboxylase activity induced by glycocholic acid. In a two-stage mouse epidermal carcinogenesis experiment using 7,12-dimethylbenz(a)anthracene as the initiator, glycocholic acid as the 1st stage promoter, and mezerein as the 2nd stage promoter, palm carotene inhibited the promoting activity of glycocholic acid. Furthermore, in N-ethyl-N'-nitro-N-nitrosoguanidine-induced mouse duodenal carcinogenesis, 0.05% of palm carotene given in drinking water decreased the percentage of tumor-bearing mice significantly.

Inhibition of azoxymethane-induced colon carcinogenesis in rat by green tea polyphenol fraction.

The effect of green tea polyphenol fraction (GTP) on azoxymethane(AOM)-induced colon carcinogenesis was investigated in male Fischer rats. The rats were given AOM (7.4 mg/kg body weight) s.c. once a week for 10 weeks. A week after the treatment, they were divided into three groups: AOM-control (26 rats), AOM-GTP1 (26 rats) and AOM-GTP2 (25 rats). AOM-GTP1 and AOM-GTP2 groups respectively received 0.01 and 0.1% GTP in drinking water from week 11 to 26. AOM-control group received tap water throughout this experiment. Autopsy on week 26 showed that tumor incidence and average numbers of tumors per rat in the AOM-GTP1 and AOM-GTP2 groups were significantly lower than those of the AOM-control group: 38.1% and 47.6% versus 77.3%; 0.6 and 0.7 versus 1.5. Thus, it was concluded that GTP inhibited the development of AOM-induced colon carcinogenesis. The inhibition by GTP did not show significant dose dependence.

Chemical engineering of the monoclonal antibody A7 by polyethylene glycol for targeting cancer chemotherapy.

The murine monoclonal antibody A7 (Mab A7) against human colon cancer was chemically modified with methoxypolyethylene glycol (PEG) (Mr 5000). A high substitution of PEG molecules on Mab A7 produced a progressive reduction in antibody-binding activity. The pharmacokinetic and immunological properties of PEG-modified monoclonal antibody A7 (Mab A7) and the PEG-modified F(ab')2 fragment, which retained their antibody-binding activity, were assessed and compared with the parent Mab A7 and the parent F(ab')2 fragment. Blood clearance of PEG-modified antibodies appeared to be diminished by PEG modification and was fitted by a two-compartment model. Low PEG-substituted Mab A7 showed less organ uptake in the liver and spleen and similar uptake in the lung and kidney, compared with the parent Mab A7. PEG-F(ab')2 showed less uptake in the liver and kidney. Both preparations exhibited less tissue:blood ratios in all resected organs as compared with parent antibodies. Tumor localization was enhanced by PEG modification for the F(ab')2 fragment, but not by PEG modification for the whole Mab A7. Multiple i.v. administration of PEG-modified antibody to rabbit did not appear to elicit a measurable immune response to the antibody portion of the conjugate. In conclusion, PEG-modified antibodies are promising reagents as drug carriers to the target tumor.