Serotonin in tubular adenomas, adenocarcinomas and endocrine tumours of the stomach. An immunohistochemical study

Nervous system and gastric cancer

The nervous system has been recently shown to exert impact on gastric cancer directly and indirectly. Gastric cancer cells invade nerve fibers to induce outgrowth and branching of neural cells, and nerve fibers in turn infiltrate into tumor microenvironment to promote progression of gastric cancer. Additionally, the neuro-immune interaction also plays an important role in gastric cancer development. The interplay of nerves and gastric cancer is mediated by many nervous system-associated factors, which can not only be synthesized and released by both cancer cells and nerve terminals, but also participate in regulation of many aspects of gastric cancer such as cell proliferation, angiogenesis, metastasis and recurrence. Furthermore, clinical researches indicate that some of these factors are significant diagnosis and prognosis biomarkers for gastric cancer. Herein, we reviewed recent advances and future prospects of the interaction between nervous system and gastric cancer.

Immunostaining of gastric cancer with neuroendocrine differentiation: Reg IV-positive neuroendocrine cells are associated with gastrin, serotonin, pancreatic polypeptide and somatostatin

We previously reported that Reg IV is associated with neuroendocrine (NE) differentiation in gastric cancers. The aim was to examine which NE hormone products are related to Reg IV-positive NE cells and their roles in gastric cancers. In the present study, we performed immunohistochemical analysis in a tissue microarray (TMA) of a consecutive series of 630 cases with ten different antibodies, including chromogranin A, synaptophysin and neural cell adhesion molecule (NCAM) as NE differentiation markers, and gastrin, serotonin, calcitonin, gastrin-releasing peptide (GRP), pancreatic polypeptide (PP), somatostatin and glucagon as NE hormones. In 630 cases, we identified 205 (33%) with NE differentiation and 147 (23%) positive for Reg IV. Reg IV-positive cases showed NE differentiation more frequently than Reg IV-negative cases (P < 0.0001). In 205 cases with NE differentiation, Reg IV-positive cases expressed serotonin (P= 0.0032) and somatostatin (P= 0.036) more frequently than Reg IV-negative cases. Double immunofluorescence staining revealed co-expression of Reg IV with gastrin, serotonin and PP. These results indicate that Reg IV might be a mediating factor of several NE hormones.

CYR61 downregulation correlates with tumor progression by promoting MMP-7 expression in human gastric carcinoma

OBJECTIVE

CYR61 (cysteine-rich 61) belongs to the CCN (CYR61/CTGF/NOV) protein family and is involved in tumorigenesis. We have previously confirmed that the level of CYR61 protein is decreased in gastric carcinoma compared with nontumoral mucosa, by conducting proteome-based analyses. In this study, we examine the relationship between CYR61 expression and clinicopathological data of MMP-7 expression in human gastric mucosae and tumors.

METHODS

Immunohistochemical and/or immunofluorescence analyses were performed to examine the histological expression of CYR61 in normal gastric mucosa, intestinal metaplasia, 33 adenomas, and 127 carcinomas. Seven gastric carcinoma cell lines were used to examine the expression of CYR61 and MMP-7 by Western blotting.

RESULTS

The CYR61-expressing cells mostly coincided with the serotonin-containing cells, not only in nontumoral epithelia, but also among tumor cells. CYR61 expression was positive (labeling index: >2%) in 43 of 49 early gastric carcinomas (87.8%) and in 19 of 78 advanced gastric carcinomas (24.4%), the frequency being significantly lower in the latter (p < 0.001). All the normal mucosae, intestinal metaplasias and adenomas were in the positive group. The reduction in CYR61 expression correlated significantly with histological differentiation (p < 0.05), depth of invasion (p < 0.001), lymphatic invasion (p < 0.001), venous invasion (p < 0.001), lymph node metastasis (p < 0.001) and clinical stage (p < 0.001). Immunohistochemistry and Western blotting revealed the expression of CYR61 to be inversely correlated with that of MMP-7 (p < 0.001).

CONCLUSIONS

CYR61 is expressed in serotonin-containing cells, and downregulation of the expression might contribute to the progression of cancer by promoting MMP-7 expression in human gastric carcinomas.

Increased responsiveness of rat colonic splanchnic afferents to 5-HT after inflammation and recovery

5-Hydroxytryptamine (5-HT) activates colonic splanchnic afferents, a mechanism by which it has been implicated in generating symptoms in postinfectious and postinflammatory states in humans. Here we compared mechanisms of colonic afferent activation by 5-HT and mechanical stimuli in normal and inflamed rat colon, and after recovery from inflammation. Colonic inflammation was induced in rats by dextran sulphate sodium. Single-fibre recordings of colonic lumbar splanchnic afferents revealed that 58% of endings responded to 5-HT (10(-4) m) in controls, 88% in acute inflammation (P<0.05) and 75% after 21 days recovery (P < 0.05 versus control). Maximal responses to 5-HT were also larger, and the estimated EC50 was reduced from 3.2 x 10(-6) to 8 x 10(-7) m in acute inflammation and recovered to 2 x 10(-6) m after recovery. Responsiveness to mechanical stimulation was unaffected. 5-HT3 receptor antagonism with alosetron reduced responses to 5-HT in controls but not during inflammation. Responses to the mast cell degranulator 48/80 mimicked those to 5-HT in inflamed tissue but not in controls, and more 5-HT-containing mast cells were seen close to calcitonin gene-related peptide-containing fibres in inflamed serosa. We conclude that colonic serosal and mesenteric endings exhibit increased sensitivity to 5-HT in inflammation, with both an increase in proportion of responders and an increase in sensitivity, which is maintained after healing of inflammation. This is associated with alterations in the roles of 5-HT3 receptors and mast cells.

Helicobacter pylori-related and -non-related gastric cancers do not differ with respect to chromosomal aberrations

Gastric carcinogenesis is strongly associated with Helicobacter pylori infection, but the underlying genetic mechanisms are largely unknown. The aim of this study was to correlate chromosomal aberrations in gastric cancer to H. pylori status and its different strains, as well as to histological type and other clinico-pathological variables. DNA from 46 gastric cancers (male/female 35/11, age 27-85 years) was extracted from formaldehyde-fixed, paraffin-embedded material and tested for chromosomal gains and losses by comparative genomic hybridization (CGH). Chromosomal aberrations with frequencies of 20% or higher were considered to be non-random changes associated with gastric cancer. The mean number of chromosomal events per tumour was 9.7 (range 0-27), with a mean of 3.2 gains (range 0-16) and 6.5 losses (range 0-15). Gains were most frequently found at chromosomes 8q and 13q (24% and 26%, respectively). Losses were predominantly found on chromosome arms 2q, 9p, 12q, 14q, 15q, 16p, 16q, 17p, 17q, 19p, 19q, and 22q (22%, 30%, 43%, 22%, 33%, 50%, 28%, 50%, 39%, 33%, 39%, and 37%, respectively). Common regions of overlap narrowed down to 2q11-14, 8q23, 9p21, 12q24, 13q21-22, 14q24 and 15q11-15. The mean number of gains was higher in tumours with metastases than in localized tumours (4.1 vs. 1.9, p=0.04). Tumours with a loss at 17p showed a higher number of losses than tumours without a 17p loss (9. 5 vs. 4.7 on average, p<0.001). Neither H. pylori status (+, n=25; -, n=21) nor H. pylori strain was correlated to the total number of events or to any specific chromosomal aberration, nor were there differences between intestinal (n=30) and diffuse (n=15) cancers or any other clinico-pathological variable tested. In conclusion, a complex of chromosomal aberrations is involved in gastric cancer, but their pattern does not depend on H. pylori status or strain, nor on the histological type of the tumour. The exact biological meaning of these aberrations in carcinogenesis needs further clarification.

Histochemical and ultrastructural analyses of glandular differentiation in typical carcinoid tumor of the hindgut

Adenomatous differentiation of typical carcinoid tumors was examined by histochemical and ultrastructural studies on 33 cases of typical carcinoids of the hindgut. Of these 33 carcinoids, 12 (36%) showed a tubular and/or acinar pattern with production of mucus as a minor component. A few tumor cells with mucous globules were scattered among tubules in these carcinoids. Ultrastructurally, microvilli were seen along the luminal surface of tubules, with both numerous mucous globules in the supranuclear area and endocrine granules in basal sites of the same cells. These results indicate that even in typical carcinoid tumors, certain tumor cells have the features of goblet cells or the open type of endocrine cells. The findings of both mucous globules and endocrine granules in the same single cells indicate a close relationship between endocrine cells and mucus-producing and/or tubule-forming cells. It is concluded that pluripotential cells producing carcinoid tumors might be able to differentiate into three types of tumor cells: (i) endocrine cells without microvilli or mucus production; (ii) cells with microvilli and no mucus product; and (iii) mucus-containing cells with microvilli.

Depressed adenoma of the stomach, revisited. Histologic, histochemical, and immunohistochemical profiles

For 52 patients with depressed adenomas of the stomach, histopathologic studies were done on 56 tumors and for 43 of them, histochemical and immunohistochemical features were examined. In addition, nondepressed adenomas (n = 57) and the depressed type of early gastric adenocarcinomas of the well-differentiated variety (n = 44) were studied as the controls. Depressed adenomas in the majority (73%) involved the entire thickness of the mucous membrane of the stomach with tubules of atypical epithelium, presenting a severe grade in many of the cases (41%). Paneth's cells were found in cases of a depressed adenoma, in significantly higher percentages (61%) than in those with a nondepressed adenoma (P less than 0.01). The frequency of cases with argyrophil cells was also higher in depressed adenoma (63%) than in nondepressed adenoma (36%) or in cases of early gastric carcinoma (32%). Carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 were noticed in tumor cells, immunohistochemically in 28% of the cases with depressed adenoma, the frequency being intermediate between cases of a benign nondepressed adenoma (6% for both CEA and CA 19-9) and cases of early gastric carcinoma (71% for CEA and 66% for CA 19-9). No difference was noticed in lectin reactivity and mucin content between depressed and nondepressed adenomas, whereas tumor cells in the early depressed carcinoma had a higher lectin reactivity and less mucin content than those seen in the adenomas. It would thus appear that depressed adenoma is a benign neoplastic lesion; however, the malignant potential of this lesion is somewhat higher than the nondepressed counterpart, as indicated by the immunoreactivity to tumor markers and follow-up results reported by colleagues previously.