Repression of the IL-6 gene is associated with hypermethylation

The expression of the IL-6 gene is usually tightly controlled and may be in duced in specific tissues after treatment with appropriate stimuli. Althoug h much is known about the inducible expression of the IL-6 gene, the molecu lar mechanisms responsible for its repression in specific tissues or cell t ypes remain poorly defined. To address this question we have studied two hu man breast carcinoma cell lines, MDA-MB-231, in which the IL-6 gene is expr essed, and, MCF-7, in which the IL-6 message is undetectable by Northern bl ot assay even in the presence of inducers. The expression of the IL-6 messa ge was estimated after treatment with 5-aza-2'deoxycytidine and the methyla tion state of the IL-6 gene was analyzed. We show herein that treatment of MCF-7 cells with an agent which reduces DNA methylation correlates with IL- 6 gene hypomethylation and increases the level of its expression. (C) 1999 Academic Press.