1. Gene-Expression Pattern and Differentiation Potential of Synovial Sarcoma Suggest its Cellular Origin as Neural Crest-Derived Cells Tatsuya Ishibe, Tomitaka Nakayama, Satoshi Nagayama, Takeshi Okamoto, Tomoki Aoyama, Koichi Nishijo, Takashi Nakamura, and Junya Toguchida Department of Orthopaedic Surgery, Institute for Frontier Medical Sciences, Kyoto University, Japan 12th CTOS meeting at Boca Raton, FL.

2. Why “synovial” sarcoma ? 1865First report Simon G., Arch Klin Chir ・ arises in para-articular region ・ microscopic resemblance to synovium 1934“Synovialsarcome” Sabrazes J. Gaz. Hebd. Sc. Med. Bordeaux ・ rarely arises in joint cavities. ・ differs from normal synovium by immunohistochemical and ultrastructural study 1984“Synovial sarcoma” is a misnomer. Miettinen M. Am J Pathol The cell-of-origin of synovial sarcoma is still unknown. Billings SD, 2004 Mod Pathol

3. Backgrounds Hypothesis: Synovial sarcoma is neural crest-derived tumor MPNST SS ＋ Same cluster We previously performed gene expression profiling of 47 soft tissue sarcomas by cDNA microarray (23,040 genes), and reported that synovial sarcoma was clustered into the same group with malignant peripheral nerve sheath tumor which is one of the neural crest-derived tumor. Nagayama et al. Cancer Res. 2002

4. Neural crest (stem) cells: NCSC - unique cell population of the vertebrate embryo - Neural tube Joseph NM Development, 2004 Cartilage & Bone Neuron Glia Melanocyte arise from the neural ectoderm and recognizable after neural tube closure Trunk Head and neck Does synovial sarcoma have similar potential as NCSC? NCSCs have multiple differentiation potential

5. Objective To estimate the origin of synovial sarcoma (SS) by investigating its gene expression and differentiation potential. 1) Gene expression of neural crest-related genes by RT-PCR 2) Chondrogenic, osteogenic and adipogenic inductions : by the same methods as mesenchymal stem cells (MSCs) 3) Neurogenic induction by FGF2, ATRA, or BMP4 Materials and Methods Fourteen cell lines including 5 SS cells Twenty-nine tumor tissues including 18 SS tumors

6. PLS LMS MFH MPNST Biphasic SYT-SSX1(+) Monophasic SYT-SSX2(+) Monophasic SYT-SSX1(+) Differentiation markers in tumor tissues Synovial sarcoma  actin CRABP1 EDN3 EDNRB MASH1 NGFR SOX9 ALP OSF2 HES1 PPARg S100b NFH COL2A1 COL9A1 chondro neuronal melano glial adipo osteo Genes related to neural crest-derived cell lineages are expressed in SS

7. YaFuSS HS-SY-IISYO-1Fuji1273/99 MSC HE stain Alcian Blue 5x10 5 cells 3D-culture for 7 days Chondrogenesis: Pellet and matrix formation assay loose Synovial sarcoma cells Pellet formation with positive Alcian blue was observed in four SS cells

8.  actin COMP SOX9 AGC YaFuSS COL2A1 HS-SY-IISYO-1Fuji1273/99MSC COL11A1 COL11A2 COL9A1 Chondrogenesis: Gene expression before and after induction - + - + - + - + - + - + Induction Chondro-related genes were significantly upregulated. COMP: cartilage oligomeric matrix protein

9.  actin ALP OC OSF2 COL1A1 Osteogenesis: Gene expression with/without induction - + YaFuSS - + HS-SY-II - + SYO-1 - + Fuji - + 1273/99 MSC Induction + Osteo-related genes were upregulated after induction. - Induction + Induction + AA + Dex +  -GP for a week or

10. YaFuSS HS-SY-IISYO-1Fuji1273/99 ALPase stain MSC control Osteogenesis: ALPase activity and Alizarin Red staining Alizarin red stain Osteo induction control Osteo induction At least one cell line shows strong osteogenic differentiation.

11. YaFuSS HS-SY-IISYO-1Fuji1273/99MSC  actin ADP PPARg AP2 Oil-red-O stain control Adipo induction - + YaFuSS - + HS-SY-II - + SYO-1 - + Fuji - + 1273/99 - + MSC Induction Adipogenesis SS cells have poor or no potential for adipogenic induction

12. BMP4  actin MASH1 - + YaFuSS - + HS-SY-II - + SYO-1 - + Fuji - + 1273/99 MASH1  actin ATRA MAP2 NFL NFM NFH Nestin YaFuSS HS-SY-II SYO-1 NMS-2 (MPNST) HT1080 SW480 MSC Fuji 1273/99 SaOS2 COLO205 NT2/D1 (neurogenic)  actin ATRA, 7days - + YaFuSS - + HS-SY-II - + SYO-1 - + Fuji - + 1273/99 BMP4, 48 ｈｒｓ Neurogenesis: neuron-related genes Without induction

13. Tuj1 / DAPI SYO-1 YaFuSSFuji1273/99 vehicle ATRA FGF2 BMP4 PC12h (positive ctrl) HS-SY-II Immunostain of Neuron-specific beta III tubulin (Tuj1)

14. YaFuSSHS-SY-IISYO-1Fuji1273/99 Gene exp. (growing phase) ++ ± Gene exp. (after induc.) ++ Pellet formation +++++ ± Alcian blue stain +++++- Gene exp. (growing phase) --+++ Gene exp. (after induc.)±±± ++ ALP stain --+ ± ++ Alizarin red stain --- ± ++ Gene exp. (growing phase) ++ + Tuj-1 stain (after FGF2) ++++ ± Gene exp. (after ATRA) +++-- Tuj-1 (after ATRA) +--+- Gene exp. (after BMP4) ---+- Tuj-1 (after BMP4) ---++- Gene exp. (growing phase) ----+ S100  (after 5-aza-dC) +- Gene exp. (after 5-aza-dC)± +++- Gene exp. (growing phase)± - ± - ± Gene exp. (after induc.) ----- Oil-red-O stain±±±±± Chondro Osteo Neuro Glial Melano Adipo Stress fiber reorgan.(FSK) ---+- Melanogenesis.(FSK) ---+-- Cartilage Neuron Glia Melanocyte Bone Neural Crest Cell Synovial sarcoma cells Similar potential These spectra of differentiation are similar to that of neural crest ++ +

15. May form ossification or calcification ・ About 30% of synovial sarcomas have calcified focus. (Enzinger FM, Cancer, 1982) May arise from cartilage in head and neck region, but not arise from articular cartilage which is not neural crest origin. ・ Arytenoid-epiglotic rim (Szuhai K, Cancer Genet Cytogenet, 2004) ・ Cricoid cartilage, Monophasic SS (Kikuchi I, Acta Cytol, 2003) May arise from neural tissue. ・ C7 spinal root (Chu PG, Mod Pathol, 2004); ・ Common digital nerve (O’Connell JX, Mod Pathol, 1996) ・ Radial nerve (Cugola L, J Hand Surg, 1985) Discussions from pathological point of view These data also support our hypothesis that “the cell-of-origin of synovial sarcoma is neural crest-derived cells.”

16. Conclusion Synovial sarcoma expressed the genes related to chondrocyte, osteocyte, neuron, glia, and melanocyte which are known to originate from neural crest stem cells. Synovial sarcoma cells had potential to differentiate into chondrocyte, osteocyte, and neuron to various extent, but not into adipocyte. This spectrum of differentiation is similar to that of neural crest stem cells, supporting our hypothesis that “the cell-of-origin of synovial sarcoma is neural crest-derived cells”.