Methylation of a CpG island within the promoter region of the KAI1 metastasis suppressor gene is not responsible for down-regulation of KAI1 expression in invasive cancers or cancer cell lines

The molecular basis for downregulation of the KAI1 metastasis suppressor ge ne in invasive and metastatic human cancers is unknown. We have used bisulp hite methylation analysis of DNA from paraffin-embedded invasive bladder tu mour samples and from bladder cancer cell lines to determine if hypermethyl ation of a CpG island within the KAI1 promoter is responsible for this effe ct. Representative invasive tumour cell lines were also exposed to 5-aza-2- deoxycytidine. We found no evidence for hypermethylation of the CpG island and suggest that mechanisms other than promoter hypermethylation are respon sible for reduced KAI1 expression in invasive bladder tumours and tumour ce ll lines. (C) 2000 Elsevier Science Ireland Ltd. Ail rights reserved.