Angiogenesis, formation of new microvessels providing oxygen and nutrient supply, is essential for tumor growth. It is dependent on the production of angiogenic growth factors by tumor cells. Angiopoietin 1 (Ang-1) and 2 (Ang-2) and their common receptor, Tie2, are thought to be critical regulators of tumor angiogenesis. We examined expression of Ang-1, Ang-2, and their common receptor Tie2 mRNAs and proteins in gastric cancers using in situ hybridization and immunohistochemistry. We also investigated the relationship between their expression and differentiation of cancer cells, lymph node metastasis, tumor size, depth of cancer cell invasion, TNM staging and microvessel density (MVD). The expression of Ang-1, Ang-2, and Tie2 mRNA in cancer cells significantly correlated with the MVD (p<0.001, <0.001 and =0.019, respectively). Ang-1 and Tie2 positivity correlated with advanced gastric cancers (p<0.05) and larger cancers had higher positive rates of Ang-1, Ang-2, and Tie2 mRNA expression (p<0.001, =0.010 and =0.039, respectively). Significant positive correlations were also found between mRNA expression of Tie2 and those of Ang-1 and Ang-2 (p<0.01 and <0.001, respectively). These findings indicate that the expression of Ang-1 and Ang-2 is important for tumor angiogenesis, and suggest a possible role of autocrine/paracrine function of angiopoietin/Tie2 system in gastric cancer progression.
Stomach Neoplasms/blood supply/*genetics/*metabolism/pathology ; Receptor, TIE-2/*genetics/*metabolism ; RNA, Neoplasm/genetics/metabolism ; RNA, Messenger/genetics/metabolism ; Neovascularization, Pathologic ; Middle Aged ; Male ; In Situ Hybridization ; Immunohistochemistry ; Humans ; Gene Expression ; Female ; Carcinoma, Signet Ring Cell/blood supply/genetics/metabolism/pathology ; Angiopoietin-2/*genetics/*metabolism ; Angiopoietin-1/*genetics/*metabolism ; Aged ; Adult ; Adenocarcinoma/blood supply/genetics/metabolism/pathology

OBJECTIVETo investigate whether correlation exists between mRNA expression of IGF-II and hepatocyte growth factor (HGF) and tumor progression and prognosis in gastric cancer.

METHODSIn situ hybridization technique was used to examine mRNA expression of IGF-II and HGF, and immunohistochemical technique was used to examine protein expression of CD34 in 105 specimens of gastric carcinoma.

RESULTSIn situ hybridization revealed that the positive rates of IGF-II mRNA and HGFmRNA were 49.5% and 57.1%, respectively. In stage T3-T4 cases, positive mRNA expression rates of IGF-II and HGF, the frequencies of vessel invasion, lymph node metastasis and distant metastasis were significantly higher than those in stage T1-T2 cases. The mean microvascular density (MVD) in stage T3-T4 tumors, vessel invasion, lymph node metastasis and distant metastasis were significantly more frequent than those in stage T1-T2 tumors. The mean MVD in tumors with positive IGF-II and HGF expressions was significantly higher than that in tumors without IGF-II and HGF expression. There were positive correlations between MVD and expression of IGF-II and HGF. The mean survival time and 5-year survival rate in cases with positive IGF-II and HGF expression and MVD value > or = 39.5 were significantly shorter those that in cases with negative IGF-II and HGF expression and MVD value < 39.5.

CONCLUSIONIGF-II and HGF promote angiogenesis in gastric cancer, and take part in tumor invasion and metastasis. They can be used as prognostic markers of gastric cancer in clinical practice.

Adenocarcinoma, Papillary ; blood supply ; metabolism ; secondary ; Adult ; Aged ; Carcinoma, Ductal ; blood supply ; metabolism ; secondary ; Carcinoma, Signet Ring Cell ; blood supply ; metabolism ; secondary ; Disease Progression ; Female ; Hepatocyte Growth Factor ; biosynthesis ; genetics ; Humans ; Insulin-Like Growth Factor II ; biosynthesis ; genetics ; Liver Neoplasms ; blood supply ; metabolism ; secondary ; Lymphatic Metastasis ; Male ; Microcirculation ; Middle Aged ; Neoplasm Invasiveness ; Neovascularization, Pathologic ; Peritoneal Neoplasms ; blood supply ; metabolism ; secondary ; Prognosis ; RNA, Messenger ; biosynthesis ; genetics ; Stomach Neoplasms ; blood supply ; metabolism ; pathology ; Survival Rate