3. Choi SJ, Oba Y, Gazitt Y, Alsina M, Cruz J, et al. (2001) Antisense inhibition of macrophage inflammatory protein 1-alpha blocks bone destruction in a model of myeloma bone disease. J Clin Invest 108: 1833–1841. 4. Abe M, Hiura K, Ozaki S, Kido S, Matsumoto T (2009) Vicious cycle between myeloma cell binding to bone marrow stromal cells via VLA-4-VCAM-1 adhesion and macrophage inflammatory protein-1alpha and MIP-1beta production. J Bone Miner Metab 27: 16–23. 5. Oshima T, Abe M, Asano J, Hara T, Kitazoe K, et al. (2005) Myeloma cells suppress bone formation by secreting a soluble Wnt inhibitor, sFRP-2. Blood 106: 3160–3165. 6. Tian E, Zhan F, Walker R, Rasmussen E, Ma Y, et al. (2003) The role of the Wnt-signaling antagonist DKK1 in the development of osteolytic lesions in multiple myeloma. N Engl J Med 349: 2483–2494. 7. Giuliani N, Morandi F, Tagliaferri S, Lazzaretti M, Donofrio G, et al. (2007) Production of Wnt inhibitors by myeloma cells: potential effects on canonical Wnt pathway in the bone microenvironment. Cancer Res 67: 7665–7674. 8. Oyajobi BO, Garrett IR, Gupta A, Banerjee M, Esparza X, et al. (2004) Role of Dickkopf 1 (DKK) in myeloma bone disease and modulation by the proteasome inhibitor velcade. J Bone Miner Res 19: 1011. 9. Gunn WG, Conley A, Deininger L, Olson SD, Prockop DJ, et al. (2006) A crosstalk between myeloma cells and marrow stromal cells stimulates production of DKK1 and interleukin-6: a potential role in the development of lytic bone disease and tumor progression in multiple myeloma. Stem Cells 24: 986–991. 10. Abe M, Hiura K, Wilde J, Shioyasono A, Moriyama K, et al. (2004) Osteoclasts enhance myeloma cell growth and survival via cell-cell contact: a vicious cycle between bone destruction and myeloma expansion. Blood 104: 2484–2491. 11. Yaccoby S, Wezeman MJ, Henderson A, Cottler-Fox M, Yi Q, et al. (2004) Cancer and the microenvironment: myeloma-osteoclast interactions as a model. Cancer Res 64: 2016–2023. 12. Tanaka Y, Abe M, Hiasa M, Oda A, Amou H, et al. (2007) Myeloma cell- osteoclast interaction enhances angiogenesis together with bone resorption: a role for vascular endothelial cell growth factor and osteopontin. Clin Cancer Res 13: 816–823. 13. Matsumoto T, Abe M (2006) Bone destruction in multiple myeloma. Ann N Y Acad Sci 1068: 319–326. 14. Damiano JS, Cress AE, Hazlehurst LA, Shtil AA, Dalton WS (1999) Cell adhesion mediated drug resistance (CAM-DR): role of integrins and resistance to apoptosis in human myeloma cell lines. Blood 93: 1658–1667. 15. Landowski TH, Olashaw NE, Agrawal D, Dalton WS (2003) Cell adhesion- mediated drug resistance (CAM-DR) is associated with activation of NF-kappa B (RelB/p50) in myeloma cells. Oncogene 22: 2417–2421. 16. Hazlehurst LA, Damiano JS, Buyuksal I, Pledger WJ, Dalton WS (2000) Adhesion to fibronectin via beta1 integrins regulates p27kip1 levels and contributes to cell adhesion mediated drug resistance (CAM-DR). Oncogene 19: 4319–4327. 17. Maeda S, Hayashi M, Komiya S, Imamura T, Miyazono K (2004) Endogenous TGF-beta signaling suppresses maturation of osteoblastic mesenchymal cells. Embo J 23: 552–563. 18. Spinella-Jaegle S, Roman-Roman S, Faucheu C, Dunn FW, Kawai S, et al. (2001) Opposite effects of bone morphogenetic protein-2 and transforming growth factor-beta1 on osteoblast differentiation. Bone 29: 323–330. 19. Alliston T, Choy L, Ducy P, Karsenty G, Derynck R (2001) TGF-beta-induced repression of CBFA1 by Smad3 decreases cbfa1 and osteocalcin expression and inhibits osteoblast differentiation. Embo J 20: 2254–2272. 20. Pfeilschifter J, Bonewald L, Mundy GR (1990) Characterization of the latent transforming growth factor beta complex in bone. J Bone Miner Res 5: 49–58. 21. Guise TA, Chirgwin JM (2003) Transforming growth factor-beta in osteolytic breast cancer bone metastases. Clin Orthop Relat Res. pp S32–38. 22. Pfeilschifter J, Mundy GR (1987) Modulation of type beta transforming growth factor activity in bone cultures by osteotropic hormones. Proc Natl Acad Sci U S A 84: 2024–2028. 23. Oursler MJ (1994) Osteoclast synthesis and secretion and activation of latent transforming growth factor beta. J Bone Miner Res 9: 443–452. 24. Oreffo RO, Mundy GR, Seyedin SM, Bonewald LF (1989) Activation of the bone-derived latent TGF beta complex by isolated osteoclasts. Biochem Biophys Res Commun 158: 817–823. 25. Tang QQ, Otto TC, Lane MD (2004) Commitment of C3H10T1/2 pluripotent stem cells to the adipocyte lineage. Proc Natl Acad Sci U S A 101: 9607–9611. 26. Date T, Doiguchi Y, Nobuta M, Shindo H (2004) Bone morphogenetic protein- 2 induces differentiation of multipotent C3H10T1/2 cells into osteoblasts, chondrocytes, and adipocytes in vivo and in vitro. J Orthop Sci 9: 503–508. TGF-b Inhibition in Myeloma 27. Tassone P, Neri P, Carrasco DR, Burger R, Goldmacher VS, et al. (2005) A clinically relevant SCID-hu in vivo model of human multiple myeloma. Blood 106: 713–716. 28. Yata K, Yaccoby S (2004) The SCID-rab model: a novel in vivo system for primary human myeloma demonstrating growth of CD138-expressing malig- nant cells. Leukemia 18: 1891–1897. 29. Ehata S, Hanyu A, Fujime M, Katsuno Y, Fukunaga E, et al. (2007) Ki26894, a novel transforming growth factor-beta type I receptor kinase inhibitor, inhibits in vitro invasion and in vivo bone metastasis of a human breast cancer cell line. Cancer Sci 98: 127–133. 30. Chen D, Zhao M, Mundy GR (2004) Bone morphogenetic proteins. Growth Factors 22: 233–241. 31. Suzawa M, Takeuchi Y, Fukumoto S, Kato S, Ueno N, et al. (1999) Extracellular matrix-associated bone morphogenetic proteins are essential for differentiation of murine osteoblastic cells in vitro. Endocrinology 140: 2125–2133. 32. Gong Y, Slee RB, Fukai N, Rawadi G, Roman-Roman S, et al. (2001) LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development. Cell 107: 513–523. 33. Boyden LM, Mao J, Belsky J, Mitzner L, Farhi A, et al. (2002) High bone density due to a mutation in LDL-receptor-related protein 5. N Engl J Med 346: 1513–1521. 34. Zangari M, Esseltine D, Lee CK, Barlogie B, Elice F, et al. (2005) Response to bortezomib is associated to osteoblastic activation in patients with multiple myeloma. Br J Haematol 131: 71–73. 35. Zangari M, Yaccoby S, Cavallo F, Esseltine D, Tricot G (2006) Response to bortezomib and activation of osteoblasts in multiple myeloma. Clin Lymphoma Myeloma 7: 109–114. 36. Ozaki S, Tanaka O, Fujii S, Shigekiyo Y, Miki H, et al. (2007) Therapy with bortezomib plus dexamethasone induces osteoblast activation in responsive patients with multiple myeloma. Int J Hematol 86: 180–185. 37. Pennisi A, Ling W, Perkins P, Saha R, X. L, et al. (2006) PTH and bortezomib suppress growth of primary human myeloma through increased bone formation In vivo [abstract]. Blood 108. 38. Yaccoby S, Ling W, Zhan F, Walker R, Barlogie B, et al. (2007) Antibody-based inhibition of DKK1 suppresses tumor-induced bone resorption and multiple myeloma growth in vivo. Blood 109: 2106–2111. 39. Edwards CM, Edwards JR, Lwin ST, Esparza J, Oyajobi BO, et al. (2008) Increasing Wnt signaling in the bone marrow microenvironment inhibits the development of myeloma bone disease and reduces tumor burden in bone in vivo. Blood 111: 2833–2842. 40. Qiang YW, Shaughnessy JD, Jr., Yaccoby S (2008) Wnt3a signaling within bone inhibits multiple myeloma bone disease and tumor growth. Blood. 41. Mohammad KS, Chen CG, Balooch G, Stebbins E, McKenna CR, et al. (2009) Pharmacologic inhibition of the TGF-beta type I receptor kinase has anabolic and anti-catabolic effects on bone. PLoS ONE 4: e5275. 42. Isufi I, Seetharam M, Zhou L, Sohal D, Opalinska J, et al. (2007) Transforming growth factor-beta signaling in normal and malignant hematopoiesis. J Interferon Cytokine Res 27: 543–552. 43. Strobl H, Knapp W (1999) TGF-beta1 regulation of dendritic cells. Microbes Infect 1: 1283–1290. 44. Pepper MS (1997) Transforming growth factor-beta: vasculogenesis, angiogen- esis, and vessel wall integrity. Cytokine Growth Factor Rev 8: 21–43. 45. Quinn JM, Itoh K, Udagawa N, Hausler K, Yasuda H, et al. (2001) Transforming growth factor beta affects osteoclast differentiation via direct and indirect actions. J Bone Miner Res 16: 1787–1794. 46. Li X, Pennisi A, Yaccoby S (2008) Role of decorin in the antimyeloma effects of osteoblasts. Blood 112: 159–168. 47. Inman GJ, Nicolas FJ, Callahan JF, Harling JD, Gaster LM, et al. (2002) SB- 431542 is a potent and specific inhibitor of transforming growth factor-beta superfamily type I activin receptor-like kinase (ALK) receptors ALK4, ALK5, and ALK7. Mol Pharmacol 62: 65–74. 48. Ogata N, Chikazu D, Kubota N, Terauchi Y, Tobe K, et al. (2000) Insulin receptor substrate-1 in osteoblast is indispensable for maintaining bone turnover. J Clin Invest 105: 935–943. 49. Hiraga T, Williams PJ, Mundy GR, Yoneda T (2001) The bisphosphonate ibandronate promotes apoptosis in MDA-MB-231 human breast cancer cells in bone metastases. Cancer Res 61: 4418–4424. PLoS ONE | www.plosone.org 14 March 2010 | Volume 5 | Issue 3 | e9870