874

The Role of Helicobacter pylori Infection and Atrophic Gastritis in Diffuse Type and Signet Ring Cell Carcinoma Fumiaki Kitahara, Tadashi Sato, Yuichiro Kojima, Masayuki A. Fujino, Yamanashi Medical Univ, Yamanashi Japan

BACKGROUND AND AIMS Effect of Helicobacter pylori (HP)infection to diffuse type gastric cancer is unsure. We conducted a case control study to evaluate the relationship between atrophic gastritis with HP infection and diffuse type gastric cancer. METHODS: The sera at the time of diagnosis from 37 signet ring cell carcinoma cases, 37 poorly differentiated adenocarcinomas, 74 intestinal type gastric cancers, and 148 controls were tested for the presence of anti-HP IgG antibody and serum pepsinogen(PG) levels. Four categories were made according to serum PG levels and HP IgG antibody. We conducted case-control studies on three cancer types. RESULTS: In signet type, serum PG I and II levels were higher than those in controls. In poorly differentiated type and intestinal type, 1/11 ratios were lower than controls and positive PG rates were higher than controls. The odds ratios were 0.97, 1.03 and 0.87 for positive HP and 1.0, 1.98 and 2.18 for positive PG of signet type, poorly differentiated type and intestinal type, respectively. The odds ratios in the category with severe atrophy (positive PG levels and negative anti-HP IgG antibody) were 1.95, 5.42 and 5.89 of signet-type, poorlytype and intestinal type, respectively. CONCLUSIONS: These results suggest the severe atrophic state really has a high risk of poorly differentiated type and intcstinal type gastric cancer. However, carcinogenesis of the signet-type is not affected by HP infection and atrophic gastritis.

875

Etiology of Spasmolytic Polypeptide Expressing Metaplasia in Atrophic Gastritis of Rats Hirokazu ¥amaguchi, IMMAG, Medical Coil of Georgia, Augusta, GA; Jeffrey R. Lee, VAMC, IMMAG, Medical Coil of Georgia, Augusta, GA; Michio Kaminishi, Univ of Tokyo, Tokyo Japan; James R. Goldenring, IMMAG, Medical Coil of Georgia, Augusta, GA

Background: Metaplastic cell lineages arise in response to chronic injury. Herein, we use a rat surgical model to study one such lineage, spasmolytic polypeptide (SP) expressing metaplasia (SPEM). Coupled with PCNA and intrinsic factor (IF) staining, we propose that a second progenitor zone gives rise to this metaplasia. Design: Surgical models, with and without carcinogen, were made in male Wistar rats. We examined 7 rats with truncal vagotomy ('IV); 5 with IV and duodeno-gaetric reflux (iV + RF); 2 with antrectomy (ANT) and Billroth I (BI); 3 with ANT and TV (BI + TV); 6 with ANT and preoperative N-methyi-N-nitro-N-nitrosoguanidi- ne(MNNG)(MNNG+ BI); 4 with ANT, iV and preoperative MNNG (MNNG+ BI+rv). MNNG was given in drinking water for 10 weeks before surgery. 30 weeks following surgery, rat stomachs were harvested. Replicate sections of formalin fixed paraffin embedded tissue were stained using a standard ABC technique. Antibodies against SP, PCNA, and IF were used. Results: All surgical models demonstrated severe gastritis and atrophy. In the rv and "13/+ RF groups, SP stained the mucous neck cells, located in the mid-portion of oxyntic glands. SPEM was not observed. PCNA-labeled nuclei were observed in the same area. In the BI group, SP stained the mucous neck cells and deeper mucoid cells. PCNA-labeled nuclei were observed in the gastric pit and glandular neck area. In the BI + TV group, chief cells and parietal cells were reduced, and SP positive mucoid cells were increased. PCNA labeled nuclei were not only observed in the glandular neck area, but were also identified at the base of the fundic glands. In the MNNG + BI and MNNG + BI + TV groups, (shown to develop remnant adenocarci- noma with a frequency of 9% and 42%, respectively), SP staining was noted in mucoid cells, at the mucous neck and at the base of the mucosa in a pattsm of SPEM. Both groups showed PCNA-labeled nuclei in two distinct zones: the physiologic mid gland zone and a zone at the deepest portion of the mucosa. Physiologic IF staining was identified in rat chief cells, however, in the MNNG + BI and MNNG + BI + iV models, IF positive cells intermingled with SPEM and PCNA positive nuclei. Conclusion: These results suggest that a second mucosal progenitor zone develops at the gland base in severe fundic gastritis. These dividing cells at the gland base may arise from an unmasking of a cryptic zone or transdifferentiation of gastric chief cells. This second zone provides metaplastic cells (SPEM) to populate the injured mucosa, and may be involved in the development of carcinoma.

876

Effects of Dietary Calcium on intestinal Polyp Formation in the Apc m~p Mouse. Sergio Huerta, Ronald W. Irwin, Pierre Ebreo, Fiona C. Young, Vay-Liang W. Go, Diane M. Harris, UCLA, Los Angeles, CA

Background: While a recent intervention human trial has shown that dietary calcium supplemen- tation can reduce colon polyp recurrence, the mechanism of this effect is not known. The present study evaluated the effects on intestinal polyp formation of various levels of dietary calcium in the diet of Apc ~ mice, which have a germline mutation analogous to that of human familial adenomatous polyposis coil (FAP). Methods: Female Apc "~' mice four to five weeks old were randomized to three groups and fed a pelleted purified diet modified from AIN-93G, but containing either 2.5 (low-calcium; n = 18), 5 (control; n = 19), or 10 g calcium/kg diet (high-calcium; n=20). Calcium was supplied as calcium carbonate (40% calcium) in the" standard mineral premix. After 12 weeks of treatment, mice were sacrificed and two observers blinded to treatment scored polyp number and size over 4-cm segments of the small intestine and over all of the large intestine. Overall effects were evaluated by one-way ANOVA and treatment effects by Dunnett's Multiple Comparison Test. Results: The mean number of polyps found in the proximal small intestine varied with level of dietary calcium (p<O.05). However, contrary to our hypothesis, feeding a high-calcium diet resulted in an 87% increase in polyp number in this segment relative to the control diet (9.1 _+ 1.3 vs. 4.9 _+ 0.8 polyps). There was no effect on polyp number on any other segment of the intestine or on total polyp number. Similarly, there was no effect on tumor load (sum of individual polyp areas) in any segment of the intestine or on total intestinal tumor load. Growth rates and feed intake were similar over all groups. Conclusions: In this mouse model with a gone mutation analogous to that of FAP, there was no effect of calcium on total tumor burden, however there was a

significant increase in polyp number in the proximal segment of the small intestine. These data suggest that dietary calcium may have different effects in this model than in human sporadic colonic polyps. Supported by the Ca/ifomia Cancer Research Program and N/H CA42710.

877

Cancer in a Azoxymethane (AOM) Mouse Model Arise in a Folate Depleted Epithelium with Abnormal Folate Uptake. Robert E. Carroll, Richard Kenny, Theresa Kucynda, Sangeeta Tyagi, Univ of illinois, Chicago, IL; Harold Said, Univ of CA, CA; Pradeep Dudeja, Univ of Illinois, Chicago, IL

Background: Folate deficiency has been linked to colon cancer. Folate depleted rats, exposed to carcinogen, develop more malignant tumors. We have previously characterized ACF forma- tion and proliferation in response to AOM administration in C57BI6J mice. These animals develop ACF after 5 wks of AOM and dysplasia in the distal colon after 30wks. This coincides with increased proliferation. We hypothesized that sustained proliferation in the distal colon could selectively reduce folata. We therefore compared proliferation, tissue folate, and folate uptake in the distal and proximal colon of AOM treated mice on a normal folate diet (2rag/ kg). Methods: Eight week old mice were divided into 2 groups which received s.c. AOM (7.5 mg/kg) weekly for 5 - 35 weeks. Proliferation was determined by vincristinearrest. Tissue folate was measured in mouse colon tumors, liver, and the proximal and distal colon by microtiter bioassay. Folate uptake was determined by tissue accumulation method utilizing 0.25/~U [3Hfolate] uptake to 10 min. Conclusions: Early proliferation is associated with normal folate levels in the entire colon through an increase in folate transport (+40%). Chronic proliferation in the distal colon results in a 3-fold decrease in tissue folate levels in parallel with reduced folate uptake activity (-70%). Liver stores remain within normal range. In response to carcinogen, folate transport is reduced which may accelerate folate depletion and subsequent malignant transformation.

RESULTS:

5 wks Con 5 wks AOM 35 wku Con 35 wk$ AOM Prolif colon Prox. 8_+1 17+0.3 7+1 6.+_2 Met/crypt Dist. 7+1 20~1 4_+1 12~1 Colon Folate Prox. 314_+19 296_+14 299-+26 302.-1:8 (ng/gm) Dist. 2 1 6 ± 2 2 241_+58 277_+19 88!-_12 Liver Fctate (~g/gm) 5+0.3 6_+0.5 4+0.6 3~0.3 Tumor Folate (no/gin) f9~_1 Folate Uptake Prox. 0.3-+.03 0.3-+.03 pmol/mglpro Dist. 0 .8+ .06 1.1±.08 0.9-+.04 0.3_+0.3

878

Effect of Indomethacin on the Growth Response, c-myc mRNA Expression, and ItTERT mRNA Expression in Colon Cancer Ceils Tadahito Shimeda, Toru Kunlyoshi, Kazuo Kojima, Yasuo Mitobe, Takahiro Mitsuhashi, Kenta ¥oshiura, Masashi ¥oneda, Hideyuki Hiraishi, Akira Terano, Dokkyo Univ Sch of Medicine, Mibu Japan

BACKGROUND:Although cyciooxygenase (COX) inhibitors (NSAIDs) are considered to he useful agents in the chemoprevention of colon cancers, the detailed mechanisms of NSAIDs action are not fully understood yet. in the present study, we investigated the effect of indomethacin on the growth response of colon cancer cells. We also examined the effect of indomethacin on the expression of c-myc and hTERT (telomerase reverse transcriptase), because c-myc is an important target gone of the APC/~-catenin pathway that is abnormal in most colon cancers, and because hTERT is an important target gene of c-myc. METHODS: HT-29 cells, derived from human colon cancer, were used. Expression of COX-1 and COX-2 was examined with RT-PCR and Western blot analysis. Growth response of the cells (DNA synthesis) was determined by ELISA which quantifies BrdU incorporation. Cell viability was examined by WST-1 assay. Amount of fragmented DNA was measured by ELISA. Quantitative RT-PCR analysis using an ABI-PRISM 7700 sequence detection system was performed to determine the level of c-myc and hTERT mRNA expression. ~-actin mRNA level was also measured for standardization. RESULTS: HT-29 cells expressed both COX-1 and COX-2. Indomethacin (15-2000/~M) suppressed DNA synthesis of HT-29 cells in a dose-dependent manner (Incubation of the cells with 500 p/vl indomethacin for 40 h caused 75% suppression). WST-1 assay also showed that higher concentrations of indomethacin (750-2000 p,M) decreased cell viability and induced cell death. This cell death was associated with the several- fold increase in the amount of fragmented DNA, suggesting that it was apoptosis. Externally applied prostaglandin E2did not antagonize the effect of indomethacin. Compared to the control condition, relative c-myc/8-actin mRNA ratios after treatment with 5OO/~M indomethacin for 6 h and 12 h were 55% and 75%, respectively. However, hTERT/~actin mRNA ratios were not significantly affected by indomethacin treatment. CONCLUSIONS: Indomethacin-induced growth suppression was associated with the downregulation of c-myc expression in HT-29 cells. However, hTERT level was not significantly affected, suggesting that mediators other than c-myc might also be involved in the regulation of hTERT expression in colon cancer cells.

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