Antiosteogenic effect of arsenic trioxide, cholecalciferol, lovastatin or their combination in vitro

Abstract

Pathological formation of bone in non-skeletal soft tissues or heterotopic ossification (HO), for which there is currently no effective treatment, is considered to be mediated by activation of Hedgehog (Hh) signaling pathway. Moreover, the biochemical mechanism of this pathological process is not fully understood. Here, we tested the efficacy of three chemical inhibitors of the Hh signaling pathway, arsenic trioxide (ATO), lovastatin (Lov) and cholecalciferol (Vitamin D) to hamper differentiation of mesenchymal stem cells (MSC) into osteoblasts or osteogenesis. Each of the three Hh inhibitors potently decreased alkaline phosphatase activity, suggesting effective suppression of osteogenic activity in Hh-impaired MSC. Gene expression analysis revealed a significant reduction in mRNA levels of chief Hh signaling marker, Gli1, following administration of Hh small molecule inhibitors. A functional link between Hedgehog and osteogenesis in native MSC cells is further established in studies involving the mix of three Hh inhibitors acting at different checkpoints of the Hh signaling pathway. Thus, a combination of small molecule inhibitors of the Hh pathway at their lower concentrations could be a novel approach for HO prophylaxis with increased efficacy and potentially reduced side effects.