LDN193189 (DM-3189) is a selective inhibitor of the BMP type I receptor that inhibits ALK2 and ALK3 (IC50=5/30 nM), with less activity against ALK4, ALK5, and ALK7. LDN193189 can be used in studies of progressive ossifying fibrous dysplasia.

ALK3:30 nM (C2C12 cells), ALK2:5 nM (C2C12 cells), BMPR1A:30 nM

C2C12 cells were seeded into 96-well plates at 2,000 cells per well in DMEM supplemented with 2% FBS. We treated the wells in quadruplicate with BMP ligands and LDN-193189 or vehicle. We collected the cells after 6 d in culture in 50 μl Tris-buffered saline and 1% Triton X-100. We added the lysates to p-nitro-phenylphosphate reagent in 96-well plates for 1 h and then evaluated alkaline phosphatase activity (absorbance at 405 nm). We measured cell viability and quantity by Cell Titer Aqueous One (absorbance at 490 nm), using replicate wells treated identically to those used for alkaline phosphatase measurements [1].

In the first experiment, SCID mice were implanted with MDA-PCa-118b tumors. After 7 days when tumors reached measurable sizes, mice were injected with LDN-193189 (3 mg/kg) or with vehicle intraperitoneally twice a day. Tumor sizes and body weights were measured weekly. Mice were injected with calcein at three days and one day prior to sacrifice. Blood was collected and tumors were weighed. A portion of the tumors were fixed in formaldehyde for micro-computed tomography, using EVS CT, or further decalcified for bone histomorphometric analysis, using the OsteoMeasure Analysis System, or flash frozen for RNA preparation. Osteocalcin in the mouse serum was determined by ELISA. In the second experiment, PCa-118b tumors were first digested with Accumax, and the isolated cells were plated overnight, digested by Accutase, resuspended in Matrigel in 1:1 ratio, and injected into SCID mice (1 × 10^6 cells/mouse) subcutaneously. Mice were treated with LDN-193189 five days post-injection [3].