Differential expression of claudin-2 in normal human tissues and gastrointestinal carcinomas
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Claudins are involved in the formation of tight junctions in epithelial and endothelial cells. Claudins form a family of 24 members displaying organ- and tissue-specific patterns of expression. In the present study, we evaluated the specificity of the claudin-2 expression in various normal human tissues and gastrointestinal cancers by quantitative reverse transcriptase–polymerase chain reaction and immunohistochemistry. In 14 various normal tissues, claudin-2 mRNA was expressed in the kidney, liver, pancreas, stomach, and small intestine; the highest level of which was detected in the kidney. Colorectal cancers (CRCs) expressed claudin-2 mRNA at high levels. Immunohistochemical analysis of claudin-2 in 146 gastric cancers (GCs) and 99 CRCs demonstrated claudin-2 expression in 2.1% of GCs and 25.3% of CRCs, respectively. There was no obvious correlation between claudin-2 expression and clinicopathological parameters of CRCs. These results suggest that the expression of claudin-2 may involve organ specificity, and increased expression of claudin-2 may participate in colorectal carcinogenesis.
KeywordsClaudin-2 Gastric Colorectal cancers
This work was supported, in part, by Grants-in-Aid for Cancer Research from the Ministry of Education, Culture, Science, Sports, and Technology of Japan and from the Ministry of Health, Labor, and Welfare of Japan. We thank Mr. Masayoshi Takatani and Ms. Mutsumi Ueda for excellent technical assistance and advice. We thank the Analysis Center of Life Science, Hiroshima University, for the use of their facilities. The experiments in this study were in accordance with the Ethical Guidelines for Human Genome/Gene Research enacted by the Japanese government.
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