tacrolimus and Osteosarcoma

Bone morphogenetic protein (BMP) is a bone-derived growth factor capable of promoting the differentiation of mesenchymal cells into osteogenic lineage pathways. Recently, immunosuppressants were reported to cause a moderate increase in osteoblastic differentiation in a rat osteoblast-like osteosarcoma cell line. If immunosuppressants can induce osteoblastic differentiation, it will be useful for bone tissue transplantation. We assessed the effect of immunosuppressants with or without BMP-4 on inducing osteoblastic differentiation in osteoblast-like and other mesenchymal cells. FK506, an immunosuppressant often used clinically, induced a dose- and time-dependent increase in alkaline phosphatase (ALP) activity, one of the markers of osteoblast differentiation, in cells derived from mesenchyma. In the presence of BMP-4, ALP activity, mRNA levels of ALP and osteocalcin increased. FK506 was found to not only stimulate osteoblastic differentiation, but also to enhance BMP-4 induced osteoblastic differentiation. These results suggest that FK506 promotes differentiation of osteoblastic cells.

Topics: 3T3 Cells; Alkaline Phosphatase; Animals; Blotting, Northern; Bone Marrow Cells; Bone Morphogenetic Protein 4; Bone Morphogenetic Proteins; Cell Differentiation; Cell Division; Cell Line; Cells, Cultured; Culture Media, Conditioned; Cyclosporine; DNA, Complementary; Dose-Response Relationship, Drug; Immunosuppressive Agents; Mesoderm; Mice; Mice, Inbred C3H; Osteoblasts; Osteocalcin; Osteosarcoma; Polymerase Chain Reaction; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sirolimus; Tacrolimus; Time Factors

The effects of three immunosuppressants (rapamycin, FK506 and cyclosporin A) on the proliferation and differentiation of rat osteoblasts-like osteosarcoma cell line, ROS 17/2.8 (ROS) cells were examined in vitro. All immunosuppressants showed a direct inhibition on the proliferation of ROS cells with different potencies. Growth inhibition by rapamycin was stronger than that by FK506 or cyclosporin A. Rapamycin caused a significant increase in alkaline phosphatase (ALP) activity and in the expression of osteopontin and osteocalcin mRNAs. FK506 caused a moderate increase in ALP activity and a decreased expression of osteopontin mRNA. Cyclosporin A caused a decrease in ALP activity and in the expression of type 1 alpha 1 collagen mRNA. Our study indicates that rapamycin directly acts on ROS cells and induces osteoblastic differentiation, however, the effect of FK506 and cyclosporin A is weak. Rapamycin significantly enhances the differentiation induced by 1,25(OH)2-vitaminD3.

Topics: Animals; Antibiotics, Antineoplastic; Calcitriol; Cell Differentiation; Cyclosporine; Immunosuppressive Agents; Osteoblasts; Osteocalcin; Osteopontin; Osteosarcoma; Polyenes; Rats; Sialoglycoproteins; Sirolimus; Tacrolimus; Tumor Cells, Cultured