OLA1 gene sequencing in patients with BRCA1/2 mutation-negative suspected hereditary breast and ovarian cancer

BACKGROUND

Of individuals with suspected hereditary breast and ovarian cancer (HBOC), approximately 30-70 % do not harbor mutations in either BRCA1 or BRCA2 gene, which suggests that these individuals have other genetic or epigenetic alterations that could lead to the onset of this hereditary disease. We have recently identified OLA1 as a novel BRCA1/BARD1-interacting protein. In the present study, we aimed to elucidate whether any genetic mutations in OLA1 are detected among patients with suspected HBOC without BRCA1 or BRCA2 mutations.

METHODS

Among 53 patients with suspected HBOC enrolled at Hoshi General Hospital, 23 patients without any BRCA1 or BRCA2 mutations were analyzed for OLA1 mutations. Genomic DNA was extracted from the peripheral blood samples. PCR and Sanger sequencing were performed to elucidate whether there were any mutations in any of the ten exons and flanking introns of the OLA1 gene.

RESULTS

No germline sequence variation was detected in the OLA1 gene among the 23 patients enrolled in this study.

CONCLUSIONS

No germline mutations were found in the OLA1 gene among the cohort of patients with suspected HBOC without BRCA1 or BRCA2 mutations. Further studies are needed to clarify whether other mutations/epigenetic alterations are involved in the pathogenesis of BRCA1 or BRCA2 mutation-negative inherited disease with breast or ovarian cancer.

Somatic alteration and depleted nuclear expression of BAP1 in human esophageal squamous cell carcinoma

BRCA1-associated protein 1 (BAP1) is a deubiquitinating enzyme that is involved in the regulation of cell growth. Recently, many somatic and germline mutations of BAP1 have been reported in a broad spectrum of tumors. In this study, we identified a novel somatic non-synonymous BAP1 mutation, a phenylalanine-to-isoleucine substitution at codon 170 (F170I), in 1 of 49 patients with esophageal squamous cell carcinoma (ESCC). Multiplex ligation-dependent probe amplification (MLPA) of BAP1 gene in this ESCC tumor disclosed monoallelic deletion (LOH), suggesting BAP1 alterations on both alleles in this tumor. The deubiquitinase activity and the auto-deubiquitinase activity of F170I-mutant BAP1 were markedly suppressed compared with wild-type BAP1. In addition, wild-type BAP1 mostly localizes to the nucleus, whereas the F170I mutant preferentially localized in the cytoplasm. Microarray analysis revealed that expression of the F170I mutant drastically altered gene expression profiles compared with expressed wild-type BAP1. Gene-ontology analyses indicated that the F170I mutation altered the expression of genes involved in oncogenic pathways. We found that one candidate, TCEAL7, previously reported as a putative tumor suppressor gene, was significantly induced by wild-type BAP1 as compared to F170I mutant BAP1. Furthermore, we found that the level of BAP1 expression in the nucleus was reduced in 44% of ESCC examined by immunohistochemistry (IHC). Because the nuclear localization of BAP1 is important for its tumor suppressor function, BAP1 may be functionally inactivated in a substantial portion of ESCC. Taken together, BAP1 is likely to function as a tumor suppressor in at least a part of ESCC.

Abstract 4955: Somatic alteration and depleted nuclear expression of BAP1 in human esophageal squamous cell carcinomas

We have found a case of somatic non-synonymous mutation of BAP1, substituting phenylalanine to isoleucine at codon 170 (F170I) out of 49 patients with esophageal squamous cell carcinomas (ESCs) examined by Sanger's direct sequencing. By in vivo Ubiquitination assay, deubiquitininase activity was suppressed in F170I, comparing with wild BAP1. BAP1 localization assay revealed that F170I mutant preferred to localize within cytoplasm although wild BAP1 mostly localizes within nucleus. Microarray analysis revealed that F170I has drastically altered gene expression profile. The following gene-ontology analyses indicated that expression of genes involved in oncogenic pathways has drastically altered by F170I. We have also found that BAP1 expression was depressed around 10% of ESCs examined by immunohistochemistry. It is interesting that nuclear BAP1-depleted cases have strong cytosolic expression of BAP1, instead. As nuclear localization of BAP1 is important in tumor suppressor function, BAP1 may be functionally inactivated around 10% of ESCs.

Citation Format: Takahiro Mori, Makiko Sumii, Fumiyoshi Fujishima, Kazuko Ueno, Masao Nagasaki, Chikashi Ishioka, Natsuko Chiba. Somatic alteration and depleted nuclear expression of BAP1 in human esophageal squamous cell carcinomas. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4955. doi:10.1158/1538-7445.AM2015-4955

Helicobacter pylori-associated gastritis is related to babA2 expression without heterogeneity of the 3' region of the cagA genotype in gastric biopsy specimens

BACKGROUND

Cytotoxin-associated gene A (cagA) is the major virulence factor of Helicobacter pylori strains and affects the clinical outcome of patients. Blood group antigen binding adhesin (BabA) helps the strains adhere to the epithelial cell layer and is the most important adhesin of H. pylori.

OBJECTIVES

We tried to study the association between the status of babA2 and cagA in H. pylori strains and histological gastritis. methods: Thirty-six patients were included. RNA was extracted from two frozen biopsy samples of the antrum and corpus, respectively, and cagA/babA2 genotypes were analyzed with reverse transcription polymerase chain reaction and direct sequencing. Two gastric specimens of the antrum and corpus, respectively, were also stained with hematoxylin and eosin to analyze H. pylori-related gastritis.

RESULTS

In the antrum, 56% of the specimens were babA2 positive and in the corpus 53%. The gastritis scores of activity and inflammation were associated with the presence of babA2 in antrum specimens but not in corpus specimens. cagA gene encoding in the CagA EPIYA-D region was detected in all samples, and the sequence was completely identical between those from the gastric corpus and antrum.

CONCLUSION

babA2 expression is heterogeneous and correlated with the extent of gastritis in the antrum, but not in the corpus, whereas cagA shows a monotonous genotype.

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.

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.

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.

Role of anti-parietal cell antibody in Helicobacter pylori-associated atrophic gastritis: evaluation in a country of high prevalence of atrophic gastritis

BACKGROUND

Helicobacter pylori plays an important part in the progression of atrophic gastritis; however, markers for predicting the progression of atrophic gastritis remain unidentified. We investigated the relation between the degree of atrophic gastritis and the amount of anti-parietal cell antibodies (APCAs) present.

METHODS

In 219 Japanese patients, APCA was investigated by enzyme-linked immunosorbent assay (ELISA) and by Western blotting. The grade of corpus atrophy was estimated by histology and serum pepsinogen levels. Serum levels of pepsinogen were evaluated by radioimmunoassay.

RESULTS

Helicobacter pylori infection did not affect the APCA levels determined by ELISA. Long-term administration of proton-pump inhibitors and H. pylori eradication did not influence the levels of APCAs. However, in H. pylori-positive patients, the levels of APCA determined by ELISA were statistically higher in patients with severe atrophy than in those with mild atrophy as determined histologically (0.67+/-0.48 versus 0.45+/-0.40; A492, mean+/-s, P=0.01) and serologically by pepsinogen levels (0.66+/-0.51 versus 0.44+/-0.40. P=0.002). The levels of pepsinogen I/II ratio were correlated with APCA levels only in the H. pylori-positive group. Western blotting showed that major antigen was identical with the beta-subunit of H+,K+-ATPase.

CONCLUSION

APCA plays an important part in the progression of corpus atrophy after H. pylori infection.

Deoxycytidyl transferase activity of the human REV1 protein is closely associated with the conserved polymerase domain

The REV1 protein is a member of the growing family of translesion DNA polymerases. A cDNA of the human REV1 gene that we had originally isolated encoded 1250 amino acids residues, which was one amino acid shorter than previously reported ones. The shorter form of REV1 was named REV1S. All individuals examined expressed equivalent amounts of REV1S and REV1 mRNA, suggesting that the REV1S mRNA is a splicing variant. We show that the REV1S protein also possesses deoxycytidyl transferase activity that inserts a dCMP opposite a DNA template apurinic/apyrimidinic site. Deletion and point mutation analysis of the REV1S protein revealed that the domain required for deoxycytidyl transferase and DNA binding activities of the REV1S protein are located in a conserved domain of translesion DNA polymerases. This result indicates that the structure of the catalytic site of the deoxycytidyl transferase closely resembles that of the translesion DNA polymerases. Therefore, the molecular mechanism of the dCMP transfer reaction of the REV1S protein and maybe also the REV1 protein might be the same as that of the dNTP transfer reaction of the translesion DNA polymerases.

Murine and human SDF2L1 is an endoplasmic reticulum stress-inducible gene and encodes a new member of the Pmt/rt protein family

We isolated murine and human cDNAs for SDF2L1 (stromal cell-derived factor 2-like1) and characterized the genomic structures. Northern blot analysis of the gene expression in various tissues revealed that both murine Sdf2l1 and human SDF2L1 genes are expressed ubiquitously, with particularly high expression in the testis. The SDF2L1 protein has an endoplasmic reticulum (ER)-retention-like motif, HDEL, at the carboxy (C)-terminus. Interestingly, SDF2L1 protein also shows significant similarity to the central hydrophilic part of protein O-mannosyltransferase (Pmt) proteins of Saccharomyces cerevisiae, the human homologues of Pmt (POMT1 and POMT2) and Drosophila melanogaster rotated abdomen (rt) protein. In a murine hepatocellular carcinoma cell line, Sdf2l1 was strongly induced by tunicamycin and a calcium ionophore, A23187, and weakly induced by heat stress but was not induced by cycloheximide. In conclusion, SDF2L1 protein is a new member of Pmt/rt protein family and Sdf2l1 is a new ER stress-inducible gene.

Acid-sensitive and alkaline-sensitive sensory neurons regulate pH dependent gastrin secretion in rat

We examined the role of capsaicin-sensitive afferent neurons in pH-dependent gastrin secretion in the rat stomach. The change in serum gastrin levels relative to changes in luminal pH (using omeprazole for luminal alkalization or 0.1 N HCl for luminal acidification) was studied after oral administration of 4% lidocaine or capsaicin-induced ablation of afferent neurons. The increase of serum gastrin levels by luminal alkalization was significantly inhibited (50%) after administration of 4% lidocaine. Capsaicin pretreatment (125 mg/kg subcutaneously over two days) inhibited the change in serum gastrin levels both the luminal alkalization (38%) and acidification (66%). Antral gastrin contents, somatostatin contents, gastrin mRNA expression, and somatostatin mRNA expression were not significantly affected by capsaicin pretreatment. Our results indicate that capsaicin-sensitive afferent neurons participate in the secretion of gastrin by luminal alkalization and inhibition of gastrin by luminal acidification.

p53 gene mutation and loss of heterozygosity of chromosome 11 in methylcholanthrene-induced mouse sarcomas

Mutations of the p53 tumor suppressor gene are the most prevalent genetic alteration observed in a wide variety of human cancers. In this study we examined 63 methylcholanthrene (MCA)-induced sarcomas from C57BL/6N x C3H/HeN F1 (BCF1) or C3H/HeN x C57BL/6N F1 (CBF1) mice for p53 gene mutations and loss of heterozygosity (LOH) of chromosome 11. Mutation analysis was done on exons 5 to 8 of the p53 gene by polymerase chain reaction-single strand conformation polymorphism analysis. This identified 53 potential mutations in 45 sarcomas. Mutations were further confirmed by direct sequencing of the region. Forty-nine of the 53 cases (94%) were missense mutations, while the rest included two nonsense mutations, one silent mutation and one insertional mutation. Spectra of base substitutions were: 25 cases (47%) of G:C-->T:A transversion, 13 cases (25%) of G:C-->A:T transition (CpG site 15%), 13 cases (24%) of G:C-->C:G transversion, a case (2%) of A:T-->T:A transversion and a case (2%) of insertion. In addition, analysis of 5 polymorphic markers of mouse chromosome 11 revealed LOH in ten cases (22%) among those carrying p53 mutations. In nine of these 10 cases, the loss involved all 5 markers. In addition, the loss was biased toward the C57BL allele (9 cases). The present study establishes the pattern of mutation of the p53 gene in MCA-induced mouse sarcomas.

Role of gastrin/CCK-B receptor in the regulation of gastric acid secretion in rat

The aim of this study was to investigate whether gastrin regulates morphological changes and alpha-subunit gene expression in parietal cells through the gastrin/CCK-B receptor on enterochromaffin-like cells by histamine release. Treatment with 100 mg/kg of YM022, a potent and selective gastrin/CCK-B receptor antagonist, for one week in rats did not alter mRNA levels of histidine decarboxylase or H+, K+-ATPase. However, parietal cell morphology predominantly changed to the resting form, although the serum gastrin concentration was significantly increased. Additional treatment with YM022 and oral omeprazole, 100 mg/kg, for one week markedly suppressed the increases of mRNA levels of histidine decarboxylase and H+, K+-ATPase and completely blocked the morphological transformation of the parietal cells to a stimulated form induced by treatment with omeprazole alone. This indicates that the morphological transformation of parietal cells to an activated form with a subsequent increase in H+, K+-ATPase synthesis caused by hypergastrinemia is mediated by increased histidine decarboxylase gene expression in enterochromaffin-like cells via gastrin/CCK-B receptors.

Evidence that endogenous GRP in rat stomach mediates omeprazole-induced hypergastrinemia

To investigate the physiological role of endogenous gastrin-releasing peptide (GRP) in regulating the release of gastrin, we evaluated the response of intragastric pH, gastrin, and GRP after omeprazole treatment in rats. A significant elevation of the plasma level of GRP (P < 0.01) and a significant reduction of the antral content of GRP (P < 0.05) were observed after the administration of 100 mg/kg omeprazole. The antral content of GRP was significantly decreased 12 h after omeprazole administration and thereafter gradually returned to control levels. Peak values for intragastric pH and plasma GRP were observed 3 h after omeprazole administration and before the peak of serum gastrin. The bombesin antagonist [D-Phe6]-bombesin-(6,13)-methyl ester significantly inhibited gastrin release after omeprazole treatment (P < 0.05). These observations indicate that omeprazole-induced inhibition of acid secretion stimulates the release of GRP and suggest that the secretion of GRP induced by omeprazole may stimulate the secretion of gastrin, at least in the early phase.

Effects of pirenzepine on omeprazole-induced gastrin gene expression in rat antral tissues

Pirenzepine has inhibitory effects on gastrin secretion both in vivo and in vitro. The aim of this study was to determine the mechanism responsible for the suppression of omeprazole-induced hypergastrinemia that occurs with pirenzepine treatment. The effects were measured in rats treated with oral omeprazole plus intraperitoneal pirenzepine or saline once daily for seven days in the antrum. The serum gastrin level increased significantly by more than sixfold with omeprazole treatment; additional treatment with pirenzepine suppressed this increase by 48%. Pirenzepine treatment did not change the level of gastrin mRNA but significantly increased the level of somatostatin mRNA. Combination treatment with omeprazole plus pirenzepine significantly decreased the gastrin mRNA level to half and significantly increased the somatostatin mRNA level up to 1.4-fold of the levels achieved with omeprazole treatment alone. These results suggest that the stimulatory effect of omeprazole on gastrin synthesis is partially blocked by pirenzepine via mediation of somatostatin synthesis in the antrum.

Effects of pirenzepine on omeprazole-induced hypergastrinemia and acid suppression in peptic ulcer patients

Omeprazole effectively suppresses acid secretion, resulting in the long-term elevation of intragastric pH and serum gastrin level. Pirenzepine has been reported to inhibit gastrin secretion. This study was carried out to examine the effects of additional pirenzepine treatment on the hypergastrinemia and gastric acid suppression induced by omeprazole. Concentrations of serum gastrin and plasma somatostatin were measured in 28 peptic ulcer patients before treatment, after omeprazole treatment (20 mg/day) for 2 weeks, and after omeprazole and pirenzepine (100 mg/day) treatment for 2 weeks. The acid inhibitory effect of pirenzepine treatment in addition to omeprazole was evaluated by 24-h intragastric pH measurement in six healthy volunteers. Serum gastrin level was increased significantly, to 2.4-fold the pretreatment level, by omeprazole treatment. Additional treatment with pirenzepine suppressed serum gastrin level to 0.6-fold the omeprazole-treatment level. The serum somatostatin level was not altered significantly either by omeprazole treatment or by omeprazole and pirenzepine treatment. In healthy volunteers whose pH 3 holding time on 24-h intragastric pH monitoring was 70% by omeprazole treatment, omeprazole and pirenzepine treatment markedly increased the pH 3 holding time, to 89%. These findings suggest that pirenzepine is useful in reducing the undesirable effects of omeprazole-induced hypergastrinemia, i.e., the excessive trophic effect of omeprazole on the acid-secreting part of the stomach and the overstimulation of acid secretion. The additional pirenzepine treatment is also effective in suppressing acid secretion.

[Clinical analysis on the course and prognosis of patients with Crohn's disease]

We analyzed 66 cases (47 males and 19 females) of Crohn's disease at Hiroshima University hospital from September 1975 to October 1994 to clarify the course and prognosis of Crohn's disease. The age at onset was 21.1 +/- 7.3 years old (mean +/- SD), terms between onset and diagnosis were 21.5 +/- 33.0 months (mean +/- SD) and observation period was 65.5 +/- 44.6 months (mean +/- SD). Sites of lesion were 18 ileum, 41 ileocolon and 7 colon. Thirty-one cases, 20 cases of which had intestinal obstruction, underwent surgical operation (12 ileum types, 18 ileocolic types, 1 colon type). The cumulative probability of surgery at one, five and ten years after onset of symptoms were 12.1%, 28.8% and 56.9%, respectively. As for cumulative probability of surgical operation at one, five and ten years after diagnosis were 25.8%, 36.7% and 74.4%, respectively. Results of the cumulative probability of surgery by anatomical involvement indicated that the ileum type had a statistically significantly higher risk than other types. In each analysis compliance to nutritional therapy was also an important prognostic factor. Overall, our results indicated that the site of lesion and the compliance to nutritional therapy were important factors which have an effect on the course and prognosis of Crohn's disease patients.

[Clinicopathologic evaluation on colorectal laterally spreading tumor (LST)]

Clinicopathologic characteristics of 92 colorectal laterally spreading tumors (LST) endoscopically or surgically resected were examined. Lesions were macroscopically classified into two categories according to their surface structure :(1) granular type (G type, 47 lesions), (2) flat type (F type, 45 lesions). The size (maximum diameter) of G type lesions was 24.7 +/- 11.3 mm (Mean +/- SD) and that of F type lesions was 14.2 +/- 7.4 mm. The size of G type lesions was significantly larger than that of F type lesions (p < 0.01). Among G type lesions, cancerous lesion was present in 2 (25.0%) of 8 lesions 10-14 mm in diameter, 2 (22.2%) of 9 lesions 15-19 mm in diameter and 19 (63.3%) of 30 lesions more than 20mm in diameter. Regarding F type lesions, cancerous lesion was present in 15 (46.9%) of 32 lesions 10-14 mm in diameter, 4 (80.0%) of 5 lesions 15-19 mm in diameter and 8 (100%) of 8 lesions more than 20mm in diameter. The incidence of carcinoma in F type lesions was higher than that in G type lesions irrespective of size. F type lesions with carcinoma showed a trend toward a higher frequency of submucosal invasion and F type lesions with adenoma revealed tendency of showing severe atypia in comparison with G type lesions. The adenomatous component of LST showed a tubulo-villous architecture in 13 (28.3%) of 46 G type lesions, however none of F type lesions had a tubulo-villous component. These results indicated that clinicopathologic characteristics of F type are obviously different from G type. Furthermore, F type had a higher malignant potential than G type and is thought to have a more important role as a precursor of colorectal carcinoma than G type.

Famotidine, a histamine-2-receptor antagonist, inhibits the increase in rat gastric H+/K(+)-ATPase mRNA induced by intravenous infusion of gastrin 17 and histamine

We examined the effects of gastrin and histamine on rat gastric H+/K(+)-ATPase, the enzyme responsible for H+ secretion, gene expression in vivo. Gastrin 17 (G 17) or histamine dihydrochloride (histamine) was continuously infused through the femoral vein of anesthetized rats. Gastric H+/K(+)-ATPase mRNA levels were measured using northern blot analysis. Infusion of G 17 and histamine increased the H+/K(+)-ATPase mRNA level significantly compared with basal control level or vehicle control level (P < 0.01). However, pretreatment with famotidine, a potent histamine-2 (H2)-receptor antagonist, inhibited the increase of rat gastric H+/K(+)-ATPase mRNA following G 17 and histamine infusion. These findings indicate that both histamine and G 17 increase expression of H+/K(+)-ATPase mRNA by activating H2 receptor on the parietal cell.

Helicobacter pylori infection is associated with low antral somatostatin content in young adults. Implications for the pathogenesis of hypergastrinemia

BACKGROUND

Recent studies on the role of Helicobacter pylori in the pathogenesis of duodenal ulcers have focused on the mechanism by which H. pylori infections cause exaggerated gastrin release.

METHODS

We determined meal-stimulated serum gastrin concentrations and antral somatostatin content in 24 asymptomatic volunteers (6 H. pylori-infected, 18 H. pylori-uninfected). Somatostatin content was determined by radioimmunoassay in biopsy specimens obtained from the antrum.

RESULTS

Fasting and integrated 2-h gastrin concentrations were significantly higher in H. pylori-positive volunteers than in H. pylori-negative volunteers (fasting, 111 +/- 16.3 pmol/l versus 53.4 +/- 3.5 pmol/l; p < 0.05; integrated 2-h, 267 +/- 41.2 pmol/l versus 70.1 +/- 2.1 pmol/l; p < 0.01). Antral somatostatin content was 0.764 +/- 0.173 ng/mg and 2.931 +/- 0.414 ng/mg in H. pylori-positive and -negative volunteers, respectively (p < 0.01).

CONCLUSIONS

Low antral somatostatin content may cause hypergastrinemia in asymptomatic healthy volunteers, and H. pylori may contribute to the pathogenesis of duodenal ulcer, through this mechanism.

Regulation of antral peptides by administration of omeprazole to healthy men

OBJECTIVES

We investigated the effects of short-term administration of omeprazole on the regulation of antral gastrin and somatostatin in 15 healthy men.

METHODS

Seven of these men were administrated 20 mg, and eight were given 40 mg of omeprazole for 8 days each. All subjects were examined before the first dose and after the last dose.

RESULTS

Each dose significantly increased the basal serum gastrin level. Although the dose of omeprazole 20 mg/day had no significant affect on the antral somatostatin content, omeprazole 40 mg/day increased the antral gastrin content and decreased the antral somatostatin content significantly. Both doses significantly increased in the antral gastrin mRNA level. However, neither dose significantly affected the antral somatostatin mRNA level.

CONCLUSIONS

This study shows reciprocal changes between the antral content of gastrin and somatostatin following omeprazole administration. These results indicate that antral somatostatin may be involved in the hypersecretion of gastrin produced by omeprazole in humans.

Expression of antral gastrin and somatostatin mRNA in Helicobacter pylori-infected subjects

OBJECTIVES

We investigated the gene expression of antral gastrin and somatostatin in Helicobacter pylori-infected subjects. Twelve asymptomatic men with normal endoscopic findings participated in this study, four of whom were infected with H. pylori.

METHODS

Biopsy specimens of the gastric mucosa were obtained after subjects had fasted overnight. Serum gastrin levels, antral gastrin and somatostatin content, and antral G- and D-cell densities also were measured.

RESULTS

Fasting serum gastrin levels were significantly higher in H. pylori-positive subjects than in H. pylori-negative subjects. There were no differences between groups in antral gastrin content, G-cell density, or gastrin mRNA levels. Antral somatostatin content, D-cell density, somatostatin mRNA levels, and the somatostatin mRNA:D-cell density ratio were significantly decreased in H. pylori-positive subjects.

CONCLUSIONS

Our results suggest that in addition to reduced antral D-cell density, a suppression of somatostatin synthesis in D-cells may have contributed to the decrease in antral somatostatin in H. pylori-infected subjects.

Effect of histamine on rat gastric H(+)-K(+)-ATPase alpha-subunit expression

The H(+)-K(+)-adenosinetriphosphatase (ATPase) is expressed in the parietal cell and is responsible for acid secretion by the stomach. Histamine binds to an H2 receptor and activates adenylate cyclase and intracellular calcium concentration ([Ca2+]i) elevation, stimulating acid secretion. It has been shown that omeprazole administered to rats increases serum gastrin and transiently increases the level of mRNA for the alpha-subunit of the pump, but this increase is blocked by the presence of the H2-receptor antagonist, famotidine [A. Tari, G. Yamamoto, K. Sumii, M. Sumii, Y. Takehara, K. Haruma, G. Kajiyama, V. Wu, G. Sachs, and J. H. Walsh. Am. J. Physiol. 265 (Gastrointest. Liver Physiol. 28): G752-G758, 1993]. These observations suggest that the release of histamine induced by gastrin is essential for the increase of the expression of mRNA induced by omeprazole. Infusion of histamine at 15 mumol.kg-1.h-1 i.v. for 1 h increased the alpha-subunit mRNA level by 144 +/- 2.4% and induced a stimulated morphological appearance of the parietal cell. These changes were inhibited completely by the competitive H2-receptor antagonist famotidine, which elevated gastric pH and serum gastrin. Famotidine also reduced the level of H(+)-K(+)-ATPase mRNA compared with control animals. No change in the expression of beta-actin mRNA was observed in any group of animals. These data provide direct evidence for histamine stimulation of H(+)-K(+)-ATPase alpha-subunit gene expression by activation of the H2 receptor.

Role of histamine2 receptor in increased expression of rat gastric H(+)-K(+)-ATPase alpha-subunit induced by omeprazole

Omeprazole is a specific inhibitor in vivo of the functioning gastric acid pump, the H(+)-K(+)-adenosinetriphosphatase (ATPase), in the secretory canaliculus of the parietal cell. It has been shown previously that omeprazole in rats led to an increase in the mRNA for the alpha-subunit of the H(+)-K(+)-ATPase. Omeprazole causes a marked increase in circulating gastrin in this species, which in turn stimulates release of histamine from the enterochromaffin-like cell. The possible role of this pathway was investigated by the in vivo administration of famotidine, a potent H2 receptor antagonist. A single intraperitoneal dose of famotidine, 200 mg/kg, produced a transient hypergastrinemia peaking at 3 h and normalizing at 12 h, inhibition of secretion that lasted for 12 h, but no change in the level of the alpha-subunit mRNA or of beta-actin mRNA. In contrast, a single dose of omeprazole, 100 mg/kg, inhibited acid secretion and produced hypergastrinemia, peaking at 12 h, both effects lasting for the 24-h observation period. Omeprazole elevated the alpha-subunit mRNA transiently by more than threefold at 3 h, with normal levels being restored at 24 h. The administration of famotidine 1 h after omeprazole did not change the effects of omeprazole on acid secretion but elevated the gastrin levels further. There was now no elevation of the alpha-subunit mRNA for the first 6 h, but a small increase at 12 h and a further increase to approximately 2.5-fold at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of rat gastric H+/K(+)-ATPase alpha-subunit mRNA by omeprazole

The H+/K(+)-ATPase is the dimeric enzyme responsible for H+ secretion by the gastric parietal cells. The present study examined the response of rat fundic mRNA levels of H+/K(+)-ATPase alpha-subunit and somatostatin to the inhibition of H+/K(+)-ATPase enzyme activity and gastric pH elevation by oral omeprazole administration. Omeprazole inhibits the alpha-subunit of H+/K(+)-ATPase covalently and stabilizes stimulated morphology of the parietal cell. After a single administration of omeprazole (100 mg/kg), H+/K(+)-ATPase alpha-subunit mRNA levels increased significantly by 57% at 3 h and remained elevated for 6 h, returning to the basal level by 24 h. After multiple administrations of omeprazole (100 mg/kg per day, every 24 h for 3 days), H+/K(+)-ATPase alpha-subunit mRNA levels were already elevated at the time of the last dose, reached maximum at 6 h (95% increase above control), and returned to the pre-treatment level after 36 h. Nuclear run-on assay indicated H+/K(+)-ATPase gene transcription was significantly increased by omeprazole pretreatment in vivo. In contrast, a significant decrease in fundic somatostatin mRNA occurred at 12 h after a single dose, and the inhibition was more pronounced and lasted longer after multiple doses of omeprazole. These data indicate that omeprazole, while effectively inhibiting H+/K(+)-ATPase activity, induces H+/K(+)-ATPase gene expression in the parietal cells. An inverse relationship exists between the regulation of somatostatin gene expression in fundic D-cells and H+/K(+)-ATPase gene expression. The increase in H+/K(+)-ATPase alpha-subunit mRNA could be due to alterations in extracellular gastrin/somatostatin ratios or could be induced by intracellular effects of omeprazole.

Regulation of rat antral gastrin and somatostatin gene expression during starvation and after refeeding

Antral gastrin and somatostatin gene expression during starvation and after refeeding with liquid meals of varying composition were studied. Northern and slot-blot hybridization analyses showed that starvation caused a marked decrease in antral gastrin messenger RNA (mRNA) level by 12 hours associated with an increase in somatostatin mRNA. After 48 hours of fasting, antral gastrin mRNA was 26% and somatostatin mRNA was 136% of their prefasting levels. Refeeding caused increased 2-hour integrated gastrin mRNA levels after liquid peptone (+45%), phenylalanine (+31%), and olive oil (+13%), but no changes were observed with glucose or saline solutions. Integrated 2-hour immunoreactive antral gastrin content was increased after peptone (+106%), phenylalanine (+68%), and olive oil (+32%) meals but was not increased after glucose (-11%) or saline (-10%). In some cases, both gastrin mRNA and peptide responses could be measured as early as 15 minutes. The same nutrients that increased gastrin mRNA levels caused decreased 2-hour integrated somatostatin mRNA levels; peptone (-30%), phenylalanine (-28%), and olive oil (-21%), but neither glucose nor saline, altered somatostatin mRNA levels. These results suggest that antral gastrin and somatostatin genes were regulated in opposite directions, in a coordinate manner, by specific gastric nutrients that stimulate gastrin release.