Transcriptional silencing of the TFPI-2 gene by promoter hypermethylation in choriocarcinoma cells

Tissue factor pathway inhibitor-2 (TFPI-2), a Kunitztype serine proteinase inhibitor associated with the extracellular matrix, has been shown to reduce tumor invasion. In the present study we identified the presence of a complete CpG island region spanning exon 1 and the three transcription initiation sites. We demonstrate that DNA demethylation by 5aza-2deoxycytidine restores TFPI-2 transcription in JAR choriocarcinoma cells. The effect of in vitro DNA methylation on TFPI-2 promoter function was also confirmed with TFPI 2/luciferase promoter constructs. Finally, we determined the precise methylation status of CpG sites of the TFPI-2 promoter in normal and tumor trophoblast cells using the bisulfite genomic sequencing method. We conclude that hypermethylation of the TFPI-2 gene is correlated with transcriptional silencing and that the TFPI-2 gene may be a candidate tumor suppressor gene.