title: Differential expression of osteogenic factors associated with osteoinductivity of human osteosarcoma cell lines.
abstract: Differential expression of multiple osteogenic factors may be responsible for the different osteoinductivity of osteosarcoma cell lines. We compared in vivo osteoinductivity of human osteosarcoma cell lines (Saos-2 vs. U-2 OS) in nude mice, and their in vitro expression of various osteogenic factors of protein level by quantitative immunocytochemistry and mRNA level by RT-PCR and/or in situ hybridization. Saos-2 cells, but not U-2 OS, were osteoinductive in vivo. Significantly higher expression (independent t-test, all p < 0.005) of osteogenic factors were observed in Saos-2 cells compared with U-2 OS, which included bone morphogenetic proteins (particularly BMPs-2, 3, 4, and 7), transforming growth factor-beta (TGF-beta), BMP receptor (BMPR)-1A, receptor-regulated Smads (R-Smads), Smads 1, 2, and 5, and common-mediator Smad (Co-Smad), Smad 4. In contrast, U-2 OS cells expressed higher levels of inhibitory Smad 6 (I-Smad) protein than Saos-2 cells (p < 0.001). These results suggest that a combination of osteogenic factors (BMPs, TGF-beta, BMPRs, and R/Co-Smads) against I-Smad may play important roles in the Saos-2 cell osteoinductivity. This may have a clinical implication in selecting key osteogenic factors for combined therapy for bone defect diseases. The characterized cell lines can be used as positive and negative controls for the assessments of both in vitro and in vivo bone formation capabilities of designed tissues or biomaterials.
authors.affiliation: Orthopaedic Research Laboratory, University of New South Wales, The Prince of Wales Hospital, Sydney, NSW 2031, Australia. y.yu@unsw.edu.au
authors.forename: Yan
authors.initials: Y
authors.lastname: Yu
authors.forename: Richard I
authors.initials: RI
authors.lastname: Harris
authors.forename: Jia-Lin
authors.initials: JL
authors.lastname: Yang
authors.forename: H Clarke
authors.initials: HC
authors.lastname: Anderson
authors.forename: William R
authors.initials: WR
authors.lastname: Walsh
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis; D045744:Cell Line, Tumor; D015194:Diffusion Chambers, Culture; D005260:Female; D006133:Growth Substances / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009999:Ossification, Heterotopic / Q000503:physiopathology*; D010012:Osteogenesis / Q000502:physiology; D012516:Osteosarcoma / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000096:biosynthesis
chemical_list: D019485:Bone Morphogenetic Proteins; D006133:Growth Substances; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta