Methylation-associated silencing of the tissue inhibitor of metalloproteinase-3 gene suggests a suppressor role in kidney, brain, and other human cancers

Tissue inhibitor of metalloproteinase-3 (TIMP-3) antagonizes matrix metallo proteinase activity and can suppress tumor growth, angiogenesis, invasion, and metastasis. Loss of TIMP-3 has been related to the acquisition of tumor igenesis. Herein, we show that TIMP-3 is silenced in association with aberr ant promoter-region methylation in cell lines derived from human cancers. T IMP-3 expression was restored after 5-aza-2'deoxycytidine-mediated demethyl ation of the TIMP-3 proximal promoter region. Genomic bisulfite sequencing revealed that TIMP-3 silencing was related to the overall density of methyl ation and that discrete regions within the TlMP-3 CpG island may be importa nt for the silencing of this gene. Aberrant methylation of TIMP-3 occurred in primary cancers of the kidney, brain, colon, breast, and lung, but not i n any of 41 normal tissue samples. The most frequent TIMP-3 methylation was found in renal cancers, which originate in the tissue that normally expres ses the highest TIMP-3 levels. This methylation correlated with a lack of d etectable TIMP-3 protein in these tumors. Together, these data show that me thylation-associated inactivation of TIMP-3 is frequent in many human tumor s.