Bone morphogenetic proteins and its receptors; therapeutic targets in cancer progression and bone metastasis?

Breast and prostate cancer are osteotropic cancers, i.e., carcinomas that have a special predilection to form bone metastases. At postmortem examination, approximately 70% of patients dying of these cancers have evidence of metastatic bone disease. Bone Morphogenetic Proteins (BMPs) were first identified by their ability to induce ectopic bone formation in vivo. Since prostate cancer cells express several BMPs, BMPs have been implicated in the osteoblastic phenotype of bone metastases. In addition to their osteogenic function, BMPs turned out to be multifunctional proteins regulating cell growth, differentiation, migration, and apoptosis in various target cells, including breast and prostate cancer cells. Especially in the last decade, studies have focused on the role of several BMPs in osteotropic cancers. In this review, the role of BMPs, particularly that of BMP7, in breast and prostate cancer will be discussed.