Sachiyo Nomura

Relation between microRNA expression and progression and prognosis of gastric cancer: a microRNA expression analysis

BACKGROUND Analyses of microRNA expression profiles have shown that many microRNAs are expressed aberrantly and correlate with tumorigenesis, progression, and prognosis of various haematological and solid tumours. We aimed to assess the relation between microRNA expression and progression and prognosis of gastric cancer. METHODS 353 gastric samples from two independent subsets of patients from Japan were analysed by microRNA microarray. MicroRNA expression patterns were compared between non-tumour mucosa and cancer samples, graded by diffuse and intestinal histological types and by progression-related factors (eg, depth of invasion, metastasis, and stage). Disease outcome was calculated by multivariable regression analysis to establish whether microRNAs are independent prognostic factors. FINDINGS In 160 paired samples of non-tumour mucosa and cancer, 22 microRNAs were upregulated and 13 were downregulated in gastric cancer; 292 (83%) samples were distinguished correctly by this signature. The two histological subtypes of gastric cancer showed different microRNA signatures: eight microRNAs were upregulated in diffuse-type and four in intestinal-type cancer. In the progression-related signature, miR-125b, miR-199a, and miR-100 were the most important microRNAs involved. Low expression of let-7g (hazard ratio 2.6 [95% CI 1.3-4.9]) and miR-433 (2.1 [1.1-3.9]) and high expression of miR-214 (2.4 [1.2-4.5]) were associated with unfavourable outcome in overall survival independent of clinical covariates, including depth of invasion, lymph-node metastasis, and stage. INTERPRETATION MicroRNAs are expressed differentially in gastric cancers, and histological subtypes are characterised by specific microRNA signatures. Unique microRNAs are associated with progression and prognosis of gastric cancer. FUNDING National Cancer Institute.

Recurrent gain-of-function mutations of RHOA in diffuse-type gastric carcinoma

Diffuse-type gastric carcinoma (DGC) is characterized by a highly malignant phenotype with prominent infiltration and stromal induction. We performed whole-exome sequencing on 30 DGC cases and found recurrent RHOA nonsynonymous mutations. With validation sequencing of an additional 57 cases, RHOA mutation was observed in 25.3% (22/87) of DGCs, with mutational hotspots affecting the Tyr42, Arg5 and Gly17 residues in RHOA protein. These positions are highly conserved among RHO family members, and Tyr42 and Arg5 are located outside the guanine nucleotide–binding pocket. Several lines of functional evidence indicated that mutant RHOA works in a gain-of-function manner. Comparison of mutational profiles for the major gastric cancer subtypes showed that RHOA mutations occur specifically in DGCs, the majority of which were histopathologically characterized by the presence of poorly differentiated adenocarcinomas together with more differentiated components in the gastric mucosa. Our findings identify a potential therapeutic target for this poor-prognosis subtype of gastric cancer with no available molecularly targeted drugs.

Chemopreventive Effect of Peroxisome Proliferator–Activated Receptor γ on Gastric Carcinogenesis in Mice

Peroxisome proliferator-activated receptor gamma (PPARgamma) is known to be expressed in several cancers, and the treatment of these cancer cells with PPARgamma ligands often induces cell differentiation and apoptosis. Recently, the chemopreventive potential of PPARgamma ligands on colon carcinogenesis was reported, although the effect of PPARgamma on colon carcinogenesis and the mechanism of the effect remain controversial. In this study, we attempted to elucidate the role of PPARgamma in gastric carcinogenesis and explored the possible use of PPARgamma ligand as a chemopreventive agent for gastric cancer. N-methyl-N-nitrosourea (MNU, 240 ppm) was given in drinking water for 10 weeks to induce gastric cancer in PPARgamma wild-type (+/+) and heterozygous-deficient (+/-) mice, followed by treatment with PPARgamma ligand [troglitazone, 0.15% (w/w) in powder food] or the vehicle alone for 42 weeks. At the end of the experiment, PPARgamma (+/-) mice were more susceptible to MNU-induced gastric cancer than wild-type (+/+) mice (89.5%/55.5%), and troglitazone significantly reduced the incidence of gastric cancer in PPARgamma (+/+) mice (treatment 55.5%/vehicle 9%) but not in PPARgamma (+/-) mice. The present study showed that (a) PPARgamma suppresses gastric carcinogenesis, (b) the PPARgamma ligand troglitazone is a potential chemopreventive agent for gastric carcinogenesis, and (c) troglitazones chemopreventive effect is dependent on PPARgamma.

Emergence of spasmolytic polypeptide-expressing metaplasia in Mongolian gerbils infected with Helicobacter pylori

Spasmolytic polypeptide (TFF2)-expressing metaplasia (SPEM) is observed in mucosa adjacent to human gastric cancer and in fundic glands showing oxyntic atrophy in Helicobacter felis-infected mice. Mongolian gerbils infected with Helicobacter pylori (Hp) develop goblet cell intestinal metaplasia and adenocarcinoma, but the presence of SPEM has not been studied in gerbils. We therefore have sought to examine the development of metaplastic mucosal changes in Hp-infected Mongolian gerbils. Mongolian gerbils were assigned to either uninfected controls or infected with Hp at 17 weeks of age. The animals were killed at 17, 20, 26, 31, 41 and 56 weeks of age. Stomach sections were stained using antibodies for TFF2, intrinsic factor, H/K-ATPase, BrdU and MUC2. Dual immunofluorescence staining for TFF2 with intrinsic factor and for TFF2 with MUC2 was performed. In uninfected animals, no SPEM or intestinal metaplasia was observed. Infected gerbils developed SPEM initially in the intermediate zone along the lesser curvature and subsequently spread out towards the greater curvature. In the earlier stages of infection, SPEM glands demonstrated TFF2 and intrinsic factor double staining cells. However, after 35 weeks of infection, the number of double staining SPEM cells decreased. While early in infection SPEM organized in straight glands, in the later stages of infections, SPEM glands became distorted or dilated along with the development of gastritis cystica profunda that was TFF2 positive. Goblet cell intestinal metaplasia developed only late in the infection. Dual staining for TFF2 and MUC2 showed glands containing both SPEM- and MUC2-positive goblet cell intestinal metaplasia. SPEM develops early in Hp infection in Mongolian gerbils, and alterations in gland morphology arise from SPEM glands during the course of gastric infection with goblet cell intestinal metaplasia developing subsequent to SPEM.

Tests for Serum Levels of Trefoil Factor Family Proteins Can Improve Gastric Cancer Screening

BACKGROUND & AIMS Improving methods for early detection of gastric cancer could reduce mortality. Measurements of serum pepsinogen levels have been used for screening in Japan without satisfactory levels of sensitivity or specificity. Trefoil factor family (TFF) proteins (TFF1, TFF2, and TFF3) are small and stable molecules secreted by the mammalian gastrointestinal tract. Foveolar hyperplasia, spasmolytic polypeptide (TFF2)-expressing metaplasia, and intestinal metaplasia are histologic changes observed in patients with atrophic gastritis; they express TFF1, TFF2, and TFF3, respectively. We investigated whether serum levels of TFF can be used as markers for gastric cancer screening. METHODS Serum was collected from 183 patients with gastric cancer and 280 healthy individuals without cancer. Serum levels of anti-Helicobacter pylori immunoglobulin G, pepsinogen I, pepsinogen II, TFF1, TFF2, and TFF3 were measured by enzyme-linked immunosorbent assay and associated with gastric cancer. RESULTS Using a cutoff of 3.6 ng/mL, the level of TFF3 was significantly increased in serum samples from patients with cancer (odds ratio, 18.1; 95% confidence interval, 11.2-29.2); using this test, patients with cancer were identified with 80.9% sensitivity and 81.0% specificity. The test for TFF3 had a significantly higher odds ratio than that for pepsinogen. A test for the combination of TFF3 and pepsinogen had better results than the test for only pepsinogen. CONCLUSIONS Serum levels of TFF3 are a better marker of gastric cancer than pepsinogen; a test for the combined levels of serum pepsinogen and TFF3 could improve gastric cancer screening.

Decreasing complication rates with stapled esophagojejunostomy following a learning curve

Background. Recently, two reports of clinical trials on gastric cancer surgery have reported high mortality following extended lymph node dissection. In these reports, anastomotic leakage at the esophagojejunostomy was observed in approximately 10% of patients, with high mortality. These data highlight the importance of avoiding this complication. In this article, we report the use of a stapler to achieve a safe anastomosis, with low incidences of leakage and postoperative stenosis.Methods. From January 1985 to December 1997, we performed 1234 esophagojejunal anastomoses at the National Cancer Center Hospital. Records of the 1234 patients were reviewed to evaluate changes in anastomotic techniques and changes in the incidence of anastomotic leakage. In this series, 588 stapled anastomoses were carried out between 1992 and 1997. These were evaluated to calculate the incidence of leakage and stenosis, with special reference to the use of supplementary sutures around the stapled anastomosis. Statistical analysis was performed by the χ2 test.Results. This series showed an overall increase in the use of staplers to form the esophagojejunal anastomosis, and a decrease in the incidence of leakage. In 1995, all anastomoses were stapled, with a leakage rate of less than 1.0%. In the last 6 years of the series (1992–1997), the leakage rate was 1.0% and the incidence of postoperative stenosis was 1.2%. The results were not improved by supplementary sutures around the stapled anastomosis.Conclusion. These data show that a stapled esophagojejunal anastomosis without supplementary sutures is a safe way to create a esophagojejunal anastomosis, with results superior to those with hand suturing. We believe the stapled anastomosis should become the “gold standard” for esophagojejunal anastomosis.

SIMULTANEOUS ONSET OF ACUTE INFLAMMATORY RESPONSE, SEPSIS-LIKE SYMPTOMS AND INTESTINAL MUCOSAL INJURY AFTER CANCER CHEMOTHERAPY

Chemotherapy is 1 method for the treatment of cancer, but serious side effects can sometimes limit the dosage given. Mild fever and diarrhea are common side effects of cancer chemotherapy. Gastrointestinal injury induced by chemotherapeutic agents may result in bacterial/endotoxin translocation from the gut into the systemic circulation. An experimental study was therefore conducted to clarify the effect of systemic chemotherapeutic agents on gastrointestinal barrier function. Male Wistar rats were divided into a 5‐fluorouracil (5‐FU) group (100 mg/kg/day for 4 days; n = 27) and a control group (n = 5). All rats were fasted and central venous catheterization was performed for total parenteral nutrition and blood sampling. Intestinal tissue was also sampled for pathological examination. Plasma levels of interleukin‐6 (IL‐6) and tumor necrosis factor α (TNFα) were determined by ELISA, bacterial translocation was quantified by lymph node culture and plasma endotoxin content of portal blood was measured by the Limulus‐amebocyte‐lysate test. In the 5‐FU group on day 4, a proportion of rats exhibited severe watery diarrhea (73.9%) and occasional vomiting (86.2%). The levels of plasma TNFα and IL‐6 were seen to increase, peaking at day 6 (IL‐6, 350.0 ± 67.8 pg/ml; TNFα, 26.1 ± 3.2 pg/ml). The pathological findings also changed on day 4. On day 6, 90% of the rats in the 5‐FU group showed dramatic sepsis‐like manifestations, whereas the control group did not. Within the 5‐FU group, only at day 6 was bacterial translocation in the rat mesenteric lymph nodes or significantly elevated levels of endotoxin evident. These results suggest that bacterial/endotoxin translocation might cause sepsis‐like manifestations after systemic chemotherapy.

Endoscopic classification of chronic gastritis based on a pilot study by the research society for gastritis

Background: Various types of classification of gastritis have been proposed, but no plausible classification has been available until now. The Research Society for Gastritis performed a pilot study to establish an endoscopic classification, taking into consideration the following: (i) ease of use; (ii) permitting everyone the common image; and (iii) presence of histopathological evidence.

Glypican 3‐expressing gastric carcinoma: Distinct subgroup unifying hepatoid, clear‐cell, and α‐fetoprotein‐producing gastric carcinomas

Gypican‐3 (GPC3) has been recognized as an oncofetal protein in hepatic neoplasms and yolk sac tumors. To characterize a distinct subgroup of gastric carcinoma (GC) expressing GPC3 (GPC3‐GC), primary and metastatic GC tissues were evaluated by immunohistochemistry with special focus on their related entities: hepatoid, clear‐cell, and α‐fetoprotein‐producing GC. GPC3‐GC was defined as focal GPC3‐GC when 10–49% of neoplastic cells were positive, and as diffuse GPC3‐GC when more than 50% of cells were positive. Among 926 GC cases, 101 (11%) were GPC3‐GC, of which 45 were diffuse and 56 were focal GPC3‐GC. Specific histological patterns, such as the hepatoid and clear‐cell patterns, were frequently observed in diffuse GPC3‐GC (38 and 49%, respectively) and in focal GPC3‐GC (4 and 25%, respectively), whereas these patterns were extremely rare in GPC3‐negative GC. Immunoreactive α‐fetoprotein was only identified in GPC3‐GC (38% of diffuse and 14% of focal GPC3‐GC). Both diffuse and focal GPC3‐GC showed nodal metastasis more frequently (67 and 55%, respectively) than GPC3‐negative GC (34%), and the diffuse GPC3‐GC had significantly more T2–4 and M1 stage cases. GPC3 immunostaining was present in 57 out of 61 nodal metastases (93%) and in all four liver metastases examined. Importantly, diffuse GPC3 expression was observed in the liver metastasis, even if the primary tumor was focal GPC3‐GC. GPC3‐GC is a distinctive group of GC, which unifies hepatoid, clear‐cell, and α‐fetoprotein‐producing GC. GPC3 is expected to be a target of forthcoming immunotherapy for a patient bearing this specific type of GC. (Cancer Sci 2009; 100: 626–632)

Surgical Treatment of Early Gastric Cancer

Around half the cases of gastric cancer are found in the early stage in Japan. With an expected good prognosis, many treatment options have been developed to maintain a good quality of life of the patients after the treatment. Gastric cancer is diagnosed with endoscopy, and the depth of invasion is diagnosed with endoscopy and endoscopic ultrasound. One of the new treatments is endoscopic submucosal dissection. Improvements in surgical treatment are minimizing lymph node dissection, reconstruction methods, laparoscopy-assisted surgery, and sentinel node navigation surgery. Minimizing lymph node dissection for early gastric cancer is well described in the Guidelines for Gastric Cancer Treatments. Pylorus-preserving gastrectomy, jejunal interposition, pouch reconstruction, and Roux-en-Y reconstruction after distal gastrectomy are improvements in reconstruction after gastrectomy. More and more surgeons start laparoscopy-assisted gastrectomy with lymph node dissection. Even with these improvements, the 5-year survival of early gastric cancer is more than 90% in Japan. Further improvements would be possible in the future.