HER2/neu over-expression induces endothelial cell retraction

Investigation of HER-2 codon 655 single nucleotide polymorphism frequency and c-ErbB-2 protein expression alterations in gastric cancer patients

AIM: To investigate both whether the risk of gastric cancer is associated with the Ile/Val single nucleotide polymorphism (SNP) of human epidermal growth factor receptor-2 (HER-2) transmembrane domain-coding region at codon 655 and the suggested existence of HER-2 expression in gastric cancer cases in a Turkish patient group.

METHODS: Polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) strategy was used to analyze the presence of HER-2 SNP at codon 655. c-erbB-2 expression pattern was analyzed by immunohistochemistry. The results were compared between gastric carcinoma group and chronic gastritis group, as well as between clinicopathological parameters and carcinoma.

RESULTS: Results showed that Ile/Val genotype accounted for 20% within the Turkish gastric carcinoma group, and none in chronic gastritis group, and this genotyping was associated with stage IV gastric cancers (P = 0.04). Positive membranous HER-2 immunoreactivity, on the other hand, accounted for 24% within the Turkish gastric carcinoma group and none from chronic gastritis cases; further, it was correlated with intestinal type carcinomas (P = 0.007), and stage III-IV carcinomas (P = 0.004).

CONCLUSION: These observations imply that the tested HER-2 SNP may participate in the development and progression of gastric cancer. Thus, after confirming these results with large sample groups, HER-2 codon 655 SNP and/or c-erbB-2 overexpression may also be used as a poor prognostic indicator for gastric carcinomas.

Hypermethylation of Syk gene in promoter region associated with oncogenesis and metastasis of gastric carcinoma

AIM: To investigate the rrelationship between methylation of Syk (spleen tyrosine kinase) gene in promoter region and oncogenesis, metastasis of gastric carcinoma. The relation between silencing of the Syk gene and methylation of Syk promoter region was also studied.

METHODS: By using methylation-specific PCR (MSP) technique, the methylation of Syk promoter region in specimens from 61 gastric cancer patients (tumor tissues and adjacent normal tissues) was detected. Meanwhile, RT-PCR was used to analyse syk expression exclusively.

RESULTS: The expression of the Syk gene was detected in all normal gastric tissues. Syk expression in gastric carcinoma was lower in 14 out of 61 gastric cancer samples than in adjacent normal tissues (χ² = 72.3, P < 0.05). No methylation of Syk promoter was found in adjacent normal tissues. hypermethylation of Syk gene in promoter was detected 21 cases in 61 gastric carcinoma patients. The rate of methylation of Syk promoter in gastric carcinoma was higher than that in adjacent normal tissues (χ² = 25.1, P < 0.05). In 31 patients with lymph node metastasis, 17 were found with Syk promoter methylation. A significant difference was noted between two groups (χ² = 11.4,P < 0.05).

CONCLUSION: Hypermethylation leads to silencing of the Syk gene in human gastric carcinoma. Methylation of Syk promoter is correlated to oncogenesis and metastasis of gastric carcinoma. Syk is considered to be a potential tumor suppressor and anti-metastasis gene in human gastric cancer.

Expression of tyrosine kinase Syk and its clinical significance in gastric carcinoma

AIM: To evaluate the effects of the Syk mRNA expression in human gastric carcinoma on tumor growth and metastasis, and the correlation of expression of the Syk gene with p53.

METHODS: Using semi-RT-PCR technique, we detected specimens from 61 gastric carcinoma patients (tumor tissues, adjacent normal tissues) for their rate and level of Syk and p53 gene expression. Meanwhile, immunohistochemical staining was also used to detect Syk expression.

RESULTS: All normal gastric tissues were detected the expression of the Syk gene. Unlike normal tissue, 47 out of 61 breast cancer tissue did not show any detectable Syk mRNA expression, and there were significant difference between the two groups (χ² = 72.3, P < 0.05). The level of Syk mRNA in the primary gastric carcinoma tissues was significantly lower than that in the adjacent non-cancerous gastric tissues (t = 2.1, P < 0.05). Furthermore, only 3 gartric carcinoma tissues in 31 patients with lymph node metastasis had the Syk mRNA expression. The Syk mRNA expression was negatively correlated to lymph node metastasis (χ² = 4.85, P < 0.05). And the Syk expression was correlated to that of p53 (χ² = 22.03, P < 0.05).

CONCLUSION: The expression of the Syk gene may play an important role in suppressing growth and metastasis in gastric cancer. Syk gene expression is repressed in a p53-dependent manner.