| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥2,200,000 (Direct Cost: ¥2,200,000)
|
|---|
| Research Abstract |
Osteoclast differentiation factor (RANKL) is requisite for osteoclasts differentiation from hematopoietic precursors. To elucidate the mechanism of osteolytic bone metastasis, we assessed RANKL gene expression and osteoclastogenesis in mouse experimental model and human bone specimen. In both mouse and human osteolytic lesion due to cancer metastasis, RANKL expression was observed on the stromal/osteoblastic cells close to the cancer cell nests.
The effect of DNA methylation on its mRNA expression and osteoclastogenesis was analyzed. Subpopulations of ST2 cells were used : P9 which expresses RANKL and P16 which does not. CpG methylation of the -65/+350 region of the RANKL gene promoter, especially 3 bases upstream of TATA-box, was higher in P16 than in P9. In vitro methylation of the promoter construct reduced the transcriptional activity,5-aza-dC treatment recovered RANKL expression of P16 cells. Methylation of the RANKL gene promoter suppresses RANKL gene expression. The heterogeneity of osteoblastic cells in response to bone-resorbing stimuli may be attributed to the methylation status of the RANKL gene promoter.
We then analyzed the RANKL gene regulation by Runx2,transcrition factor essential for osteoblastic differentiation. We analyzed ST2 cells and Runx2 null mouse-derived C6 cells by RT-PCR,ChIP assay, and siRNA silencing. Runx2 suppresses the steady-state RANKL gene expression by condensing chromatin, while showing a slightly positive effect on RANKL basic promoter.
We have presented our data at various international as well as domestic meetings, and published scientific papers for academic journals.
|
