The pathobiological behaviors and prognosis associated with Japanese gastric adenocarcinomas of pure WHO histological subtypes.

Japan is a high-risk region for gastric carcinoma with a comparatively early stage and favorable prognosis. To clarify the pathobiological behaviors and prognosis of Japanese gastric adenocarcinoma, we analyzed the clinicopathological characteristics of different WHO subtypes of carcinomas. The expression of ki-67, CPP32, p53, FHIT, maspin, parafibromin, GRP78, GRP94, EMMPRIN, VEGF, P-GSK3beta-ser9, fascin, cortactin, Arp2, Arp3 MUC-2, MUC-5AC and MUC-6 was examined using immunohistochemistry and tissue microarrays. The majority of cases were well-, poorly-, or moderately-differentiated subtype, whereas the minority were papillary or signet ring cell carcinoma (SRC). Patients with poorly-differentiated or SRC carcinoma were predominantly young and female. Poorly-differentiated and mucinous carcinomas were larger, with deeper invasion, more venous or lymphatic invasion, frequent lymph node involvement and peritoneal dissemination, or higher staging. The SRC group exhibited weaker expression of ki-67, CPP32, p53, parafibromin, GRP78, GRP94, P-GSK3beta-ser9, VEGF or cortactin. The moderately-differentiated subtype exhibited lower expression of FHIT and Arp3 positivity. The poorly-differentiated group showed weaker expression of CPP32, EMMPRIN, MUC-2, MUC-5AC, and MUC-6. Survival analysis indicated that the patients with poorly-differentiated or mucinous subtypes had a lower cumulative survival rate than those with papillary, well-, moderately-differentiated, or SRC carcinomas (P<0.05). The age, invasive depth, lymphatic invasion, peritoneal dissemination, and WHO classification were independent prognostic factors for carcinoma patients (P<0.05). It was suggested that poorly-differentiated and mucinous subtypes are more aggressive and of unfavorable prognosis among Japanese gastric carcinomas. Lower levels of proliferation and apoptosis, as well as alterations in tumor suppressor genes, mucin production and ER stress protein played important roles in the pathogenesis of poorly-differentiated and SRC carcinomas.