The purpose of the study was to evaluate the methylation status of the interleukin-10 (IL-10) gene in breast cancer tissues compared with normal and benign breast disease tissues. Between 2000 and 2001, we used paraffin-embedded specimens of 30 normal, 31 benign and 72 breast cancer tissues from the National Cancer Center, Korea. The methylation patterns of the IL-10 gene were evaluated using bisulfite DNA sequencing and the expression levels of IL-10 mRNA were evaluated using real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) and reverse transcriptase-polymerase chain reaction (RT-PCR). The methylation rates of the IL-10 gene were significantly lower in malignant tumors than in benign and normal tissues (normal; 63.3%, benign; 74.2%, cancer; 45.8%, p = 0.02). The methylation density rates of the IL-10 gene were also significantly lower in malignant tumors (normal; 59.68 ± 7.12%, benign; 48.89 ± 7.45%, cancer; 30.56 ± 4.18%, p = 0.001). Tissues with aberrant methylation of the IL-10 gene showed significantly lower rates of mRNA expression compared with unmethylated cases (12.5% vs. 68.0%, p = 0.012). The mRNA expression of tissues with unmethylated IL-10 was upregulated approximately ten thousand-fold compared to those with IL-10 methylation in the real-time RT-PCR experiment. IL-10 methylation demonstrated a significant association with lower expression of Ki-67 (9.36 ± 2.43 vs. 19.68 ± 3.42, p = 0.02). IL-10 methylation in cancer tissues is lower than that in normal and benign breast tissues, and DNA hypomethylation in the gene influences gene activation. Our data suggest that hypomethylation of the IL-10 gene can be involved in the process of breast carcinogenesis.

No abstract

Thyroid-stimulating-hormone-alpha (TSH-Į) is the common subunit of the heterodimeric hormone TSH and also of other glycoprotein hormones. Although both expression and promoter-methylation profiles of the gene have been observed in the pituitary gland and placenta, no observation has been reported in the thyroid gland. We examined TSH-Į expression in normal and cancer thyroid tissues. Real-time RT-PCR and immunohistochemistry indicated that TSH-Į was repressed in normal tissues while activated in cancer tissues. To identify the epigenetic mechanism of upregulation of TSH-Į, the methylation status of the seven CpG sites in the TSH-Į promoter was examined in sixty thyroid cancer tissues. Two CpG sites showed remarkably higher levels of methylation in cancer (46 and 45%) than in normal tissues (24 and 23%) (p = 0.010 and 0.003). These findings indicate that TSH-Į is expressed in the thyroid cancer tissue per se and that its expression can be affected by promoter methylation.

No abstract