DNA methylation through prostaglandin in colon carcinogenesis

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1.The effects of prostaglandin (PG) E_2 and PGJ_2 on gene expression were studied using cDNA microarray. Several genes were identified. Results of some genes were not compatible with that of PCR, and these discrepancies were under investigation.2.Levels of P1GF protein were not affected by PG.3.Among several cytokines, PGE_2 and PGJ_2 dramatically reduced TNF-α production by human macrophages.4.COX-2, a prostaglandin synthetase, was expressed in subepithelial mesenchymal cells of early colon cancer, laterally spreading tumor, and colon adenoma.5.COX-2 expressing cells were α-smooth actin negative and partly CD68 positive. Therefore, these cells were partly macrophages but not myofibroblasts.6.To investigate the methylation of APC genes, expression of β-cathenin, which is inactivated by APC protein, was studied. Transfer of this protein from cytoplasm to nucleus was not observed in adenomas, but was found in colon cancer.