etion increased STAT3 activation, tumorigenesis and tumor growth. Thus, these findings indicate that the association between NF ��B and STAT3 could be dif ferent according to the cancer cell type investigated and, thus, interaction of these two molecules in terms of cancer cell metastasis in each cancer type needs to be elucidated. Since the relationship between NF ��B and STAT3 path ways in gastric cancer has not been described previously, the present study performed a large scale immunohisto chemical analysis to investigate the correlation between NF ��B p65 and phospho Tyr705 STAT3 or matrix metalloproteinase 9 in 255 surgically excised human gastric carcinoma tissues. In addition, we inhibited NF ��B in gastric cancer cells by transduction with a retroviral vector containing supersuppressive mutant form of I��B and silenced STAT3 by transfection of STAT3 small interfering RNA.

Then, we evalu ated the effect of NF ��B and STAT3, alone or in combin ation, on the gastric cancer cell migration and invasion in vitro. Methods Patients and tissue array methods A total of 255 surgically resected human gastric cancer Brefeldin_A specimens were obtained from the Department of Path ology, Seoul National University College of Medicine from January 1st to June 30th, 1995 and six paraffin array blocks were prepared by Superbiochips Laborator ies, as previously described. Briefly, core tissue biopsies were taken from individual paraffin embedded gastric tumors and arranged in a new recipient paraffin block using a trephine apparatus.

The staining results of the different intratumoral areas of gastric carcinomas in these tissue array blocks showed an excellent agreement. A core was chosen from each case for analysis. We defined an adequate case as a tumor occupying more than 10% of the core area. Each block contained internal controls consisting of non neoplastic gastric mucosa from body, antrum and other areas showing intestinal metaplasia. Sections of 4 um thickness were cut from each tissue array block, deparaf finized, and rehydrated. This protocol was reviewed and approved by the Institutional Review Board of Seoul Na tional University. Immunohistochemistry Immunohistochemical staining was performed as described previously using a streptavidin peroxidase procedure after antigen retrieval using an autoclave. The primary antibodies used were anti NF ��B RelA, anti phospho Tyr705 STAT3, anti MMP9.

Immunostaining results were considered to be positive if 10% or 5% of the neoplastic cells were stained. Cell culture SNU 638 and MKN1, which are well characterized human gastric cancer cell lines, were purchased from the Korean Cell Line Bank. Cells were cultured in RPMI1640 supplemented with 10% fetal bovine serum, 2 mg mL sodium bicarbonate, 100 U mL penicillin, and 100 ug mL streptomycin at 37 C in a humidified 95% air and 5% CO2 atmosphere. Infection with retroviral vectors expressing I��B supersuppressor The control retroviral vector MFG. EGFP. IRES. puro has been previously d