[Refined mapping of the loss of heterozygosity on chromosome 1q21 in gastric carcinoma].

OBJECTIVE: To obtain allelic loss mapping and define the minimal lost region on chromosome 1q21 in gastric carcinomas, and explore role of 1q21 loss of heterozygosity (LOH) in the development and progression of gastric carcinogenesis. METHODS: Using 7 high-density microsatellite markers and PCR method, lq21 LOH was analyzed in 30 paired specimens of fresh gastric carcinoma, and the relation between 1q21 LOH and the clinicopathological features of the malignancy was tested. RESULTS: The LOH frequency on chromosome 1q21 from these gastric carcinoma tissues reached 60% (18/30). The LOH frequencies of the microsatellite markers D1S514, D1S2696, D1S498, D1S305, D1S2624, D1S2635 and D1S2702 were 13.3%, 10%, 20%, 23.3%, 33.3%, 40% and 23.3%, respectively. The minimal lost region on 1q21 LOH in the gastric carcinoma tissues was located in the region between D1S2624 and D1S2707, in the vicinity of D1S2635. No significant relations of 1q21 LOH to the patients' age, gender, location of the primary foci, clinical staging, or the tumor differentiation were noted (P>0.05), but 1q21 LOH was correlated to lymph node metastases of the malignancy (P<0.05). CONCLUSION: Higher frequency of 1q21 LOH occurs in gastric carcinoma cells, suggesting the presence of potential tumor suppressor genes closely associated with gastric carcinogenesis near the region of D1S2635.

Detection and location of Helicobacter pylori in human gastric carcinomas.

AIM: To define the infection status of Helicobacter pylori in 109 patients with gastric cancers and H pylori localization in gastric carcinoma tissues in South China. METHODS: The incidence of H pylori infection in gastric carcinomas was estimated by polymerase chain reaction (PCR), simultaneously; both morphological features and the localization of H pylori in gastric carcinomas were demonstrated by Warthin-Starry (WS) staining. The relationships between H pylori infection and the clinical-pathologic factors of gastric carcinomas were analyzed by software SPSS10.0. RESULTS: H pylori was found in 42 (39.03%) and 58 (53.21%) cases of 109 patients with gastric carcinomas by PCR and WS, respectively. H pylori infection rate detected in gastric carcinomas by WS was higher than that by PCR (chi2 = 9.735, P < 0.005 < 0.01). WS stain showed that H pylori existed in the gastric antrum mucus, mucosal gland of normal tissues adjacent to gastric carcinomas and the gland, mucus pool of cancer tissues. The positive rate of H pylori in normal tissues adjacent to carcinomas was higher than that in cancer tissues (chi2 = 15.750, P < 0.005 < 0.01). No significant differences in age, sex, site, histological types and lymph node metastasis were found between H pylori-positive gastric carcinomas and H pylori-negative cases by both methods, but there were statistically significant differences of H pylori positive rate between early and advanced stage of gastric carcinomas (chi2 = 4.548 or 5.922, P = 0.033 or 0.015 < 0.05). CONCLUSION: These results suggested that H pylori infection might play a certain role in the early stage of carcinogenesis of human gastric mucosa epithelia.

[Molecular pathological characteristics of human B-cell lymphomas induced by Epstein-Barr virus].

To identify molecular features of neoplasms associated with EB virus, human peripheral blood lymphocytes (huPBL) were isolated from healthy volunteer donors and were transplanted intraperitoneally into SCID mice, and then huPBL/SCID mice were infected with EB virus. Serum levels of human IgG were measured by unidirectional immunodiffusion assay. Human Alu sequence and EBER-1 in tumor tissues were detected with PCR and in situ hybridization. Immunohistochemical staining was used to examine leukocyte differentiation antigens (LCA, L26, UCHL1, PS1), viral gene products (LMP1, EBNA2, BZLF1) and cellular oncoproteins (p53, C-myc, Bcl-2 and Bax). The experiments showed that tumors developed in 24 of 34 surviving huPBL/SCID mice by EBV infection. Histopathological and immunohistochemical observations demonstrated that all of the induced tumors in SCID mice were malignant lymphomas derived from human B-lymphocytes. In situ hybridization showed that tumor cells had EBV-encoded small RNA-1 (i.e. EBER-1). Alu sequence could be amplified by PCR from human genome of tumor tissues. Immunohistochemistry detected positive staining of BZLF1-encoded protein in a small population of tumor cells of almost all cases, and positive staining of LMP1 and EBNA2 only in small number of tumor cells. Human IgG could be found in the serum of 12 SCID mice on the 15th day after huPBL engraftment, and then increased with time and with the development of induced tumors in 6 mice. Positive rates of p53, C-myc, Bcl-2 and Bax expression were 83.33%, 100%, 95.83%, 91.67%, respectively, in 24 cases of the EBV-induced lymphomas. The results indicate that molecular lesions associated with the induced B-cell lymphoma involved EBV infection, expression of oncogenic viral genes, and abnormal expression of cellular oncogenes in human xenografts. Human IgG level in the serum of huPBL/SCID mice can be considered as a useful index for tumor development.