KRAS mutation leads to decreased expression of regulator of calcineurin 2, resulting in tumor proliferation in colorectal cancer.

KRAS mutations occur in 30-40% of all cases of human colorectal cancer (CRC). However, to date, specific therapeutic agents against KRAS-mutated CRC have not been developed. We previously described the generation of mouse models of colon cancer with and without Kras mutations (CDX2P-G22Cre;Apc(flox/flox); LSL-Kras(G12D) and CDX2P-G22Cre;Apc(flox/flox) mice, respectively). Here, the two mouse models were compared to identify candidate genes, which may represent novel therapeutic targets or predictive biomarkers. Differentially expressed genes in tumors from the two mouse models were identified using microarray analysis, and their expression was compared by quantitative reverse transcription-PCR (qRT-PCR) and immunohistochemical analyses in mouse tumors and surgical specimens of human CRC, with or without KRAS mutations, respectively. Furthermore, the functions of candidate genes were studied using human CRC cell lines. Microarray analysis of 34 000 transcripts resulted in the identification of 19 candidate genes. qRT-PCR analysis data showed that four of these candidate genes (Clps, Irx5, Bex1 and Rcan2) exhibited decreased expression in the Kras-mutated mouse model. The expression of the regulator of calcineurin 2 (RCAN2) was also observed to be lower in KRAS-mutated human CRC. Moreover, inhibitory function for cancer cell proliferation dependent on calcineurin was indicated with overexpression and short hairpin RNA knockdown of RCAN2 in human CRC cell lines. KRAS mutations in CRC lead to a decrease in RCAN2 expression, resulting in tumor proliferation due to derepression of calcineurin-nuclear factor of activated T cells (NFAT) signaling. Our findings suggest that calcineurin-NFAT signal may represent a novel molecular target for the treatment of KRAS-mutated CRC.

Regression of rectal MALT lymphoma after antibiotic treatment in a patient negative for Helicobacter pylori.

A 53-year-old man was referred to our hospital with bloody stool. Barium enema study and colonoscopy revealed multiple small nodules on the anterior wall of the lower rectum. Biopsy specimens showed proliferation of atypical lymphoid cells forming the nodules. Mucosa-associated lymphoid tissue lymphoma was diagnosed on the basis of histologic and immunohistochemical examinations. No metastasis was detected in lymph nodes or distant organs, indicative of clinical stage I disease. Although the test results were negative for Helicobacter pylori, eradication therapy was performed. The lesion disappeared completely within 9 months after the triple antibiotic therapy. H. pylori eradication therapy may be a useful treatment option regardless of H. pylori status.

Loss of heterozygosity on chromosome 10p14-p15 in colorectal carcinoma.

High frequencies of loss of heterozygosity (LOH) on chromosome 10p14-p15 have been reported in various tumors, including gliomas, pulmonary carcinoid tumors and cervical, hepatic, prostatic and esophageal carcinomas. However, LOH on chromosome 10p14-p15 in colorectal tumors has not been reported. Therefore, we examined LOH on chromosome 10p14-p15 in 60 colorectal carcinomas (21 superficial and 39 advanced types) by microsatellite assay. Three microsatellite loci, D10S191 (10p14), D10S558 and D10S249 (10p15) were examined by polymerase chain reaction [early colorectal carcinomas, LOH of markers D10S191 (36%), D10S558 (7%) and D10S249 (11%), and in advanced colorectal carcinomas, LOH of markers D10S191 (20%), D10S558 (13%) and D10S249 (33%)]. There were no significant associations between LOH on chromosome 10p14-p15 and clinicopathologic features, including patient age, sex, tumor location, depth of invasion, histologic type, lymph node metastasis and prognosis. These data suggest that a putative tumor suppressor gene associated with colorectal carcinogenesis may be located on chromosome 10p14-p15 and that alteration of this gene may be involved in the development but not progression of colorectal tumors.

Morphological changes in human gastric tumours after eradication therapy of Helicobacter pylori in a short-term follow-up.

BACKGROUND: It is controversial as to whether the development of gastric cancer is influenced by Helicobacter pylori eradication. If eradication itself influences the tumour morphology, this may affect the tumour discovery rate. AIM: To investigate the morphological changes in the gastric neoplasm after H. pylori eradication. METHODS: We studied 37 patients with eradication therapy. After a 1-month follow-up, endoscopic re-evaluation was performed and the appearance was compared with first image. All lesions were resected endoscopically, and were subjected to histological assessment and to immunohistochemistry. Serum gastrin levels were determined before and after eradication. RESULTS: Twenty-nine of 37 patients underwent successful eradication. The appearance of 11 lesions (33% of 33 lesions) became indistinct after successful eradication. All lesions were of the superficial-elevated type and the height of the lesions decreased. We detected normal columnar epithelium over the neoplasm in eight of the lesions. Higher expression of single-stranded deoxyribonucleic acid in the deep area was characteristic in tumours with an indistinct appearance. These changes did not correlate with the serum gastrin levels. CONCLUSIONS: The morphology of the gastric neoplasm change after eradication in the short-term. This may contribute to the decreased tumour discovery rate.

Diagnostic ability of high-frequency ultrasound probe sonography in staging early gastric cancer, especially for submucosal invasion.

BACKGROUND: Advances in gastrointestinal endoscopy have resulted in endoscopic mucosal resection becoming the main therapy for many early gastric cancers confined to the mucosa and, in some cases, of minimal submucosal invasion. Thus, preoperative determination of the depth of the cancer is important. We compared the results of high-frequency ultrasound probe sonography with those of histologic study to clarify the usefulness of identifying of submucosal invasion and determining the depth of early gastric cancer. METHODS: Subjects were 295 patients diagnosed with early gastric cancer who had undergone endoscopic mucosal or surgical resection. High-frequency ultrasound probe sonographic findings were compared with histologic findings. RESULTS: The muscularis mucosae was visualized in 63% of cases of early gastric cancer. By construction on receiver operator characteristics curve, we determined that submucosal invasive cancer could be diagnosed by high-frequency ultrasound probe sonography to a depth of about 600 microm. There was no case in which invasion deeper than 1000 microm was diagnosed as a hypoechoic area limited to the mucosal layer or a fan-shaped hypoechoic area in the submucosal layer. The depth of early gastric cancer was accurately determined in 90% of cases. CONCLUSIONS: High-frequency ultrasound probe is a useful tool for accurately determining the depth of invasion of early gastric cancer when its limitations are understood.

Chronic gastritis with expression of inducible nitric oxide synthase is associated with high expression of interleukin-6 and hypergastrinaemia.

BACKGROUND AND AIMS: High levels of inducible nitric oxide synthase and nitrotyrosine in Helicobacter pylori-infected gastric mucosa may contribute to development of gastric cancer. We investigated the relation between expression of inducible nitric oxide synthase and proinflammatory cytokines in gastric mucosa and serum markers of gastritis. METHODS: The study included 103 patients with H. pylori infection. We examined levels of interleukin-1beta, interleukin-6 and interleukin-8 by enzyme-linked immunosorbent assay and evaluated expression of inducible nitric oxide synthase and nitrotyrosine by immunohistochemical staining. Furthermore, we assessed serum levels of pepsinogens, gastrin, anti-parietal cell antibody, nitrite and nitrate, as markers of gastritis. RESULTS: Thirty-seven of 103 (35.6%) gastric mucosa specimens showed simultaneous expression of inducible nitric oxide synthase and nitrotyrosine. In these patients (inducible nitric oxide synthase-positive group), the serum level of gastrin was significantly higher than that of the inducible nitric oxide synthase-negative group (509.5 +/- 141.5 pg/mL vs. 210.0 +/- 227.2 pg/mL; P < 0.01), whereas there were no significant differences in serum levels of pepsinogen, anti-parietal cell antibody, and nitrate and nitrite or in scores of histological gastritis. Interleukin-6 levels were significantly higher in the inducible nitric oxide synthase-positive group than in the inducible nitric oxide synthase-negative group (25.9 +/- 7.0 pg/mg protein vs. 10.6 +/- 4.9 pg/mg protein; P < 0.05). CONCLUSIONS: Inducible nitric oxide synthase-producing gastritis was correlated with high levels of interleukin-6. Patients with hypergastrinaemia should be carefully followed on a long-term basis to ensure that the development of any malignancy is detected early.

The specific expression of hypoxia inducible factor-1alpha in human gastric mucosa induced by nonsteroidal anti-inflammatory drugs.

BACKGROUND: Hypoxia is a cause of gastric mucosal damage induced by nonsteroidal anti-inflammatory drugs (NSAIDs). The expression of hypoxia inducible factor-1alpha (HIF-1alpha) reflects the status of tissue ischaemia. AIM: To investigate the effect of NSAID administration on the expression of HIF-1alpha in human gastric mucosa. METHODS: We employed 71 patients including 14 with NSAID administration. The HIF-1alpha expression was estimated by immunohistochemistry using monoclonal antibody (H1alpha67) and raised antiserum (HI-3). Vascular endothelial growth factor expression was also examined by immunohistochemistry. HI-3 recognized hypoxia-induced protein in HeLa cells. RESULTS: In human gastric mucosa, HIF-1alpha was mainly expressed in the nuclei of the surface epithelial cells and in the neck zone both by use of HI-3 and of H1alpha67. The expression of vascular endothelial growth factor correlated well with that of HIF-1alpha. The level of HIF-1alpha in the surface epithelium was significantly higher in patients with administration of NSAIDs than those without NSAID use (P < 0.001) both in the gastric corpus and antrum. Helicobacter pylori infection did not affected the levels of HIF-1alpha. Long-term administration of rebamipide reduced the level of HIF-1alpha. CONCLUSION: HIF-1alpha expression is a new biological marker of ischaemia especially in NSAID-related gastric lesions.

Helicobacter pylori infection influences tumor growth of human gastric carcinomas.

BACKGROUND: Helicobacter pylori infection is considered a risk factor for gastric carcinoma. However, the effect of eradication therapy in gastric carcinoma patients is not well known. The aim of this study was to investigate the relationship between H. pylori infection and tumor growth of gastric carcinoma. METHODS: Fifty-one patients with gastric carcinoma participated in the study. Thirty-three were H. pylori-positive, 6 were H. pylori-negative, and 12 were diagnosed with gastric carcinoma after eradication of H. pylori. To investigate tumor growth of gastric carcinoma, cell proliferation and angiogenesis of the tumors were evaluated by immunohistochemical techniques using Ki-67 and CD34. RESULTS: The Ki-67 labeling index was 47.9 +/- 2.6 (mean +/- s) in the H. pylori-positive group, 38.1 +/- 3.6 in the H. pylori-eradicated group, and 22.2 +/- 5.5 in the H. pylori-negative group. It was significantly lower in the H. pylori-eradicated and H. pylori-negative groups than in the H. pylori-positive one, and a significant difference was also found between the H. pylori-positive and H. pylori-eradicated groups. The microvessel counts were 62.5 +/- 3.0, 50.2 +/- 4.0, and 66.0 +/- 9.8 in the positive, eradicated, and negative groups, respectively. A significant difference was found between the H. pylori-positive and H. pylori-eradicated groups. CONCLUSION: Our results suggest that H. pylori infection is associated with cell proliferation, and its eradication may influence tumor vascularity of gastric carcinoma. Therefore, H. pylori eradication therapy may contribute to the suppression of tumor growth.

Human telomerase reverse transcriptase, p53 and Ki-67 expression and apoptosis in colorectal serrated adenoma.

BACKGROUND: Serrated adenoma (SA) has recently been proposed as a distinct histological lesion of the colorectum. However, no definite histopathologic criteria for SA have been established, and its histogenesis and natural history remain unclear. METHODS: We analysed 25 hyperplastic polyps (HPs), 26 low-grade SAs (LG-SAs), 32 high-grade SAs (HG-SAs), 18 low-grade tubular adenomas (LG-TAs), 16 high-grade TAs (HG-TAs) and 20 carcinoma in situ (CIS). To clarify molecular features of SA, we used in situ hybridization to examine the expression of human telomerase reverse transcriptase (hTERT), immunohistochemistry to examine the expressions of p53 and Ki-67, and in situ DNA nick end labeling to detect apoptotic cells. RESULTS: The incidence of hTERT expression was 1 (4.0%) of 25 for HP, 12 (46.2%) of 26 for LG-SA, 18 (56.3%) of 32 for HG-SA, 6 (33.3%) of 18 for LG-TA, 7 (43.8%) of 16 for HG-TA, 12 (80.0%) of 15 for CIS, respectively. The incidence of hTERT expression in SA was significantly higher than that in HP. Seventeen (29%) of the 58 SAs were regarded as positive for p53 protein, but none of the HPs showed p53 immunoreactivity. Ki-67 labeling index in SA, TA and CIS was significantly higher than that in HP. The apoptototic index was not significantly different between HP, SA, TA and CIS. In HG-SA, the incidence of hTERT expression in p53-positive lesions was significantly higher than that in p53-negative lesions. CONCLUSIONS: These results suggest that hTERT and p53 expression increase in the early stages of carcinogenesis in SA and that SA has a malignant transformation similar to that of TA. It may be useful to investigate hTERT and p53 expression for differential diagnosis of SA from HP.

Helicobacter pylori eradication therapy improves atrophic gastritis and intestinal metaplasia: a 5-year prospective study of patients with atrophic gastritis.

AIM: : To investigate the effect of the eradication of Helicobacter pylori on histological gastritis. METHODS: : Twenty-six patients with moderate to severe atrophy received successful eradication therapy of H.pylori. Four patients dropped out and 22 were followed up prospectively for 5 years. The grades of gastritis were estimated from gastric biopsy specimens. The grade of intestinal metaplasia was also evaluated by dye-endoscopy using methylene blue (methylthioninium chloride). The serum levels of pepsinogen, gastrin and anti-parietal cell antibody were also determined. RESULTS: : The grades of atrophy decreased in patients with successful eradication therapy in the gastric corpus (before vs. 5 years after eradication, 2.09 +/- 0.15 vs. 0.91 +/- 0.17; P < 0.01) and in the antrum (2.14 +/- 0.17 vs. 1.36 +/- 0.17; P < 0.01). The levels of intestinal metaplasia were also decreased in the corpus (0.91 +/- 0.24 vs. 0.50 +/- 0.16; P < 0.05) and in the antrum (1.41 +/- 0.20 vs. 1.00 +/- 0.16; P < 0.05), which was also demonstrated by the methylene blue (methylthioninium chloride) staining method (33.4 +/- 8.2% vs. 23.0 +/- 6.5%; P < 0.05). The improvement of corpus atrophy correlated well with the high serum level of pepsinogen I (P = 0.005), but showed no correlation with the levels of anti-parietal cell antibody. CONCLUSIONS: : These results suggest that gastric atrophy and intestinal metaplasia are reversible events in some patients.

Vascular endothelial growth factor-C expression predicts lymph node metastasis of human gastric carcinomas invading the submucosa.

We examined the relationship between vascular endothelial growth factor (VEGF)-C expression and lymph node metastases in gastric carcinomas invading the submucosa. Of the six human gastric carcinoma cell lines, two constitutively expressed VEGF-C mRNA. In three of 12 gastric biopsy specimens (25%), VEGF-C mRNA was detected in tumour tissues, but not in corresponding normal mucosa by reverse transcriptase-polymerase chain reaction (RT-PCR). Of the 139 resected gastric carcinomas, 44 (32%) showed intense cytoplasmic VEGF-C immunoreactivity in many cancer cells at the invading edge. VEGF-C immunoreactivity was associated with greater depth of tumour invasion, lymphatic invasion and lymph node metastases. In addition, vessel count was also significantly higher in the VEGF-C immunoreactive tumours than in other tumours. These results suggest that VEGF-C may be involved in the progression of human gastric carcinoma, particularly via lymphangiogenesis. VEGF-C expression at the invading edge of a gastric carcinoma may be a sensitive marker for metastasis to the lymph nodes.

Preoperative assessment of gastric cancer vascularity by flash echo imaging.

BACKGROUND: Tumor vascularity as indicated by immunohistochemical staining is a significant prognostic factor in gastric and other cancers. Non-invasive preoperative assessment of the vascularity of gastric cancers has not been possible. We aim to determine the reliability of harmonic flash echo imaging (FEI) for assessment of vascularity of gastric cancers by comparison with CD34 staining of resected specimens. METHODS: Twelve patients undergoing surgical resection of advanced gastric cancer were studied. An ultrasound system transmitting ultrasound pulses at 2.3 MHz and receiving them at 4.6 MHz (second harmonic image) was used for harmonic FEI. Approximately 30 s after intravenous injection of ultrasonic contrast medium (SHU 508A, Levovist), second harmonics (4.6 MHz) emitted from microbubbles were obtained to enhance the B-mode images. Using the tumor image showing strongest enhancement in each FEI series, regions of interest were determined to measure mean echo intensity in the tumor. Immunohistochemistry using antibodies against CD34 was carried out in resected specimens. Tumor vascularity was determined by counting stained microvessels. RESULTS: A significant positive correlation was noted between sonographic amplitude determined preoperatively by FEI analysis and number of CD34-stained microvessels in tumor specimens (r = 0.869, P = 0.004). CONCLUSION: Vascularity of gastric cancers now can be evaluated non-invasively by harmonic FEI.

Long-term rebamipide therapy improves Helicobacter pylori-associated chronic gastritis.

We investigated an antiinflammatory effect of rebamipide [2-(4-chlorobenzoylamino)-3-[2(1H)-quinolinon-4-yl] propionic acid], a gastroprotective agent, in H. pylori-associated gastritis. Eighty-six patients with H. pylori-positive chronic gastritis were enrolled: 53 were treated with rebamipide (300 mg daily for 12 months) and 33 served as controls. Significant decreases in mononuclear cell infiltration into the antrum and corpus were noted in the rebamipide treatment group (before vs after, 1.42 +/- 0.15 vs 1.02 +/- 0.15; P < 0.01 and 1.60 +/- 0.15 vs 1.21 +/- 0.14; P < 0.05, respectively). Levels of infiltrating neutrophil were also decreased in the antrum (before vs after, 0.98 +/- 0.14 vs 0.70 +/- 0.13; P < 0.05) and were associated with a decrease in iNOS production. Sera from patients treated with rebamipide showed a significant decrease in gastrin (276.3 +/- 58.3 pg/ml vs 173.0 +/- 34.2 pg/ml; P < 0.05), whereas no change was observed in the control group. These suggest that long-term rebamipide treatment improved histologic gastritis and decreased serum gastrin levels in H. pylori-associated gastritis.

A low 13C-urea breath test value is associated with increased risk of gastric cancer.

PURPOSE: The 13C-urea breath test (UBT) is considered to be the most accurate way of diagnosing Helicobacter pylori infection. Values are affected by H. pylori infection and by the severity of atrophic gastritis. Our objective was to determine the association of UBT values with gastric cancer, and to evaluate the risk of gastric cancer in terms of UBT values. METHODS: Our study involved 413 consecutive patients who had undergone esophagogastroduodenal examination and the UBT test. RESULTS: Of the 398 patients with positive UBT results, atrophy and intestinal metaplasia scores in both antrum and corpus were significantly higher in patients with gastric cancer than in those with gastritis, duodenal ulcer, and gastric ulcer. The UBT value related to gastric cancer (22.01 +/- 1.89%o) was significantly lower than that for gastritis (35.19 +/- 1.53%o; P < 0.01), duodenal ulcer (29.01 +/- 1.97%; P < 0.05), or gastric ulcer (30.79 +/- 2.83%; P < 0.05). When the UBT values were less than 20%, increases in the risk of gastric cancer correlated with decreasing UBT values. CONCLUSIONS; These findings indicate that the UBT value related to gastric cancer is significantly lower than that for gastritis, duodenal ulcer, or gastric ulcer in H. pylori-positive patients. Low UBT values were associated with the risk of gastric cancer.

Angiogenesis at the site of deepest penetration predicts lymph node metastasis of submucosal colorectal cancer.

PURPOSE: Intratumor microvessel count has been reported as a useful prognostic factor in patients with cancer of various organs. This study was undertaken to clarify the relation between microvessel count and lymph node metastasis in submucosal colorectal cancer. METHODS: Microvessel count was estimated in 254 invasive tumors that had been resected from patients with submucosal colorectal cancer. Immunohistochemistry with antibodies against CD34 was performed on archival specimens, and microvessel counts were estimated based on the average count of three fields (original magnification, x400) in the most vascular area at the site of deepest submucosal penetration. RESULTS: Microvessel count ranged from 10 to 98, with a median of 40. Lesions with high microvessel counts (> or =40) had a significantly higher incidence of lymph node metastasis than those with low microvessel counts (<40; 21.8 percent vs. 6.2 percent). None of the 79 lesions with low microvessel counts and submucosal invasion up to a depth of 1,500 microm had metastasized to the lymph nodes. In multivariate analysis, microvessel count was an independent risk factor for lymph node metastasis in submucosal colorectal cancer (P = 0.0026). CONCLUSION: Microvessel count at the site of deepest submucosal penetration can be one of the most useful predictors for lymph node metastasis. Analysis that combines microvessel count and depth of submucosal invasion may predict the occurrence of lesions without lymph node metastasis.

MUC1 and cathepsin D expression in early colorectal carcinoma showing V type pit pattern.

The relation between MUC1, cathepsin D expression, and histologic features in early colorectal carcinomas (CRCs) with V type pit pattern was examined in 78 patients. We classified V type pit pattern into two grades (VA, VN) and we subclassified the VN type pit pattern into three subtypes (Grade A, B, and C) according to the degree of appearance of VN type pit pattern. At the tumor surface, the status of desmoplastic reaction and pit disorder or destruction were subclassified histologically into three grades (-, +, ++). MUC1 and cathepsin D expression were examined immunohistochemically at a superficial level and at the deepest part of the tumor invasion. MUC1 expression showed a significant correlation with high grade carcinoma, desmoplastic reaction (+) levels in VA type pit pattern (P<0.05), and high grade carcinoma, sm2 and sm3 lesions, desmoplastic reaction (+) and (++) levels, pit disorder or destruction (+) and (++) levels in VN type pit pattern (P<0.05). Cathepsin D expression had a significant correlation with m and sm1 lesions and desmoplastic reaction (-) levels in VN type pit pattern (P<0.05). In VA type pit pattern, a significant correlation between cathepsin D expression and histologic findings was absent. The incidence of MUC1 expression in VN.Grade B and C type pit pattern was significantly higher than that in VA and VN.Grade A type pit pattern (P<0.05). The incidence of cathepsin D expression in VA, VN.Grade A and B type pit pattern was significantly higher than that in VN.Grade C type pit pattern (P<0.05). MUC1 expression (+) or (++) levels at the deepest part of a tumor was identical to that (+) or (++) levels at the superficial part except for one case. Cathepsin D expression at the deepest part of a tumor differed from that at the superficial part. Desmoplastic reaction may be related to MUC1 and cathepsin D expression; however, pit disorder or destruction may be related to only MUC1 expression in V type pit pattern. MUC1 expression at the superficial part of a tumor may be related to expression at the deepest part; however, cathepsin D expression at the superficial part may not be related to expression at the deepest part in submucosal CRCs with V type lesions.

Interleukin 8 and vascular endothelial growth factor -- prognostic factors in human gastric carcinomas?

Gastric carcinoma cells express potent angiogenic factors including vascular endothelial growth factor (VEGF). We previously reported that interleukin-8 (IL-8) acts as an angiogenic factor for human gastric carcinomas. More recently, we found that IL-8 upregulates matrix metalloproteinase-9 (MMP-9) expression and increases invasive activity of gastric carcinoma cells. The purpose of this study was to determine whether the expression of IL-8 and VEGF correlates with clinicopathological parameters in human gastric carcinomas. IL-8 and VEGF expression levels were measured by an enzyme-linked immunosorbent assay (ELISA) in 56 gastric carcinomas and the surrounding normal mucosa. Macroscopic and histopathological tumour findings, presence of metastasis and prognosis were obtained from the patient records and endoscopic, surgical and pathological reports. IL-8 protein levels were higher in most neoplasms than in the corresponding normal mucosal tissue. In contrast, VEGF expression in the tumours was similar to that in normal mucosa. The IL-8 level in the neoplasms correlated significantly with the depth of invasion, venous invasion and lymphatic invasion. VEGF expression in the tumours correlated well with the depth of invasion and lymph node metastasis. No correlation between IL-8 and VEGF expression in the tumours was observed. The survival rates of patients with tumours displaying high IL-8 and VEGF expression levels were significantly lower (P<0.05) than those of patients with tumours displaying low IL-8 and VEGF expression. The results suggest that IL-8 and VEGF may be independent and important prognostic factors in human gastric carcinomas.

Clinicopathological features of gastric mucosa-associated lymphoid tissue lymphoma: a comparison with diffuse large B-cell lymphoma without a mucosa-associated lymphoid tissue lymphoma component.

BACKGROUND AND AIMS: The aim of this study was to clinicopathologically distinguish the pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma without a MALT lymphoma component (DLL). METHODS: We investigated clinicopathological features of these gastric lymphomas including age, sex ratio, tumor location and depth, macroscopic appearance, and infection with Helicobacter pylori of these gastric lymphomas and hepatitis viruses in 24 patients with gastric low-grade MALT lymphoma, 10 patients with high-grade MALT lymphoma, and 19 patients with DLL. The frequency of H. pylori infection in lymphoma patients was compared with that in age- and sex-matched control subjects. RESULTS: There was a predominance of females with MALT lymphoma (male to female ratio, 8/16 for low-grade MALT lymphomas and 1/9 for high-grade MALT lymphomas), and there was a predominance of males with DLL (male to female ratio, 13/6); the ratios differed significantly (P < 0.05). Ninety-two percent of low-grade MALT lymphomas and 80% of high-grade MALT lymphomas were confined to the mucosal and submucosal layers, but lymphoma cells invaded the muscular layer or more deeply in 74% of DLL. Helicobacter pylori infection occurred significantly more often in patients with low-grade MALT lymphoma than in age- and sex-matched controls (96 vs 67%, P < 0.01). Conversely, the frequency of H. pylori infection in DLL patients did not differ from that in controls. CONCLUSIONS: These data suggest that H. pylori infection may be associated with the development of gastric MALT lymphoma, but not DLL, and that MALT lymphoma and DLL may have a different pathogenesis.

Clinicopathological significance of vascular endothelial growth factor (VEGF)-C in human esophageal squamous cell carcinomas.

The purpose of this study was to investigate the expression of vascular endothelial growth factor (VEGF) -C in human esophageal squamous cell carcinomas to elucidate its role in lymph node metastasis and tumor progression. The expression of VEGF-C and flt-4 genes was examined in 5 esophageal carcinoma cell lines, 12 fresh biopsy specimens and 48 archival surgical specimens of human esophageal carcinoma tissues by RT-PCR and immunohistochemistry. Immunohistochemistry using antibodies against CD34 (endothelial cell specific) was also carried out and microvessels were quantified by counting vessels in a 200x field in the most vascular area of the tumor. Of the 5 human esophageal carcinoma cell lines, 4 constitutively expressed VEGF-C mRNA. In 8 (66.7%) of 12 cases, VEGF-C mRNA was detected in only tumor tissues but not in normal mucosa by RT-PCR. There was a significant relationship between VEGF-C and flt-4 mRNA expression. Out of the 48 surgical specimens of esophageal carcinomas, 19 (39.6%) and 10 (20.8%) exhibited intense VEGF-C immunoreactivity in the cytoplasm of many cancer cells and the stromal cells, respectively. In contrast, Flt-4 was mainly expressed on the lymphatic endothelial cells. Normal and dysplastic esophageal squamous epithelium exhibited no or faint cytoplasmic staining of VEGF-C. VEGF-C expression correlated with depth of tumor invasion, tumor stage, venous invasion, lymphatic invasion and lymph node metastasis. Vessel count was significantly higher in the VEGF-C positive tumors than in the negative tumors. These results overall suggest that VEGF-C may play a role in tumor progression via lymphangiogenesis and angiogenesis in human esophageal carcinoma.