Gene expression of osteoprotegerin and osteoclast differentiation factor in giant cell tumor

To investigate the gene expression of osteoprotegerin (OPG) and osteoclast differentiation factor (ODF/TRANCE/RANKL), two new members of the TNF-receptor superfamily, in giant cell tumor (GCT); to discuss the molecular mechanism of extensive bone resorption caused by GCT.

Using TRIzol reagent to prepare total RNA from GCT sample and normal bone tissue. By a first-strand complementary DNA (cDNA) synthesis kit, cDNA was synthesized from 2.0 micro g RNA according to the manufacturer's instructions. cDNA was then amplified by PCR. Amplification products were resolved by electrophoresis on a 1.5% agarose gel and stained with EB. The relative quantity of the PCR products were determined and the mRNA levels of OPG, ODF, M-CSF (cofactor of ODF), and RANK (receptor of ODF) were compared with that of the normal bone.

GCT contained highly expressed mRNA of ODF, OPG, M-CSF and RANK. There was mRNA expression of OPG, M-CSF and RANK and less expression of ODF in normal bone. The ODF mRNA and RANK mRNA in GCT were more abundant than that in normal bone. In GCT, the ratio of ODF mRNA exceeded OPG expression. But in normal bone, the OPG mRNA exceeded ODF expression.

The results suggest that GCT contains all signals including OPG, ODF, M-CSF and RANK that are essential for inducing osteoclastogenesis and promoting bone resorption.