Expression of Angiopoietin 1, 2 and Their Common Receptor Tie2 in Human Gastric Carcinoma: Implication for Angiogenesis

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.

Expression of Epidermal Growth Factor Receptor Related Protein in Gallbladder Cancer: An Association with p53 Mutation

BACKGROUND: It has been well demonstrated that the overexpression of epidermal growth factor receptor (EGFR) is associated with numerous gastrointestinal malignancies, including gallbladder carcinoma. However, the cellular events that regulate EGFR in cancer cells have not been fully elucidated. A novel negative regulator of EGFR that is referred to as EGFR related protein (ERRP) has recently been identified. The aim of this study was to investigate the expression and localization of ERRP in gallbladder carcinoma and to examine a possible role for ERRP. METHODS: We examined the immunohistochemical expressions of ERRP, p53 and proliferating cell nuclear antigen labeling index (PCNA-LI) in formalin-fixed, paraffinembedded specimens of 43 cases of gallbladder carcinoma, 7 cases of adenoma and 3 cases of dysplasia. RESULTS: In the normal mucosa, ERRP immunoreactivity was positive in over 64% of specimens. In contrast, the ERRP staining was positive in only 46% of the cancer specimens. The expression of ERRP in cancer cells was inversely correlated with tumor cell proliferation. The loss of ERRP expression correlated with the p53 overexpression. CONCLUSIONS: Our data indicate that the down-regulation or loss of ERRP could play an important role in the progression of gallbladder carcinoma. The inverse relationship between the ERRP expression and PCNA-LI suggests that ERRP may play a role in the inhibition of tumor cell proliferation in gallbladder cancer.

Co-Expression of Cox-2, C-Met and beta-catenin in Cells Forming Invasive front of Gallbladder Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Gallbladder cancer is a malignancy with poor prognosis, predominantly resulting from invasion and metastasis. Our previous studies have demonstrated that prostaglandin E2 (PGE2), generated by cyclooxygenase 2 (Cox-2), transactivates epidermal growth factor receptor (EGFR), c-Met and beta-catenin; thus, enhancing colon cancer cell growth and invasiveness in vitro. To determine whether these findings are applicable to clinical conditions, we examined the expression and cellular localization/co-localization of Cox-2, c-Met, beta-catenin, EGFR and c-erbB2 in gallbladder cancer. MATERIALS AND METHODS: Thirty-five specimens of invasive gallbladder cancer, 8 in situ carcinoma and 7 adenoma specimens were immunostained with specific antibodies against Cox-2, c-Met, beta-catenin, EGFR and c-erbB2. The cellular distribution, localization and co- localization were examined, and the signal intensities quantified in: a) the central area of gallbladder cancer and b) cancer cells forming the invasive front. RESULTS: Cox-2, c-Met, beta-catenin, c-erbB2 and EGFR were over-expressed in 80, 74, 71, 62 and 11% of invasive gallbladder cancers, respectively. beta-catenin was expressed in 80% of non-malignant specimens, exclusively in the cell membrane, while the cancer specimens showed cytoplasmic and/or nuclear staining. Significantly higher Cox-2, c-Met and beta-catenin expressions were present in cancer cells of the invasive front than in the tumor central areas (p<0.001), and these expressions were significantly (p=0.01) associated with the invasion depth. Co- expressions of Cox-2, c-Met, beta-catenin and c-erbB2 were present in 42% of the specimens in cancer cells forming the invasive front. CONCLUSION: The overexpressions, and often co-localizations, of Cox-2, c-Met and beta-catenin in cancer cells forming the invasive front indicate their local interactions and important roles in invasion.