title: The SYT-SSX fusion protein down-regulates the cell proliferation regulator COM1 in t(x;18) synovial sarcoma.
abstract: Chromosomal translocations are frequently associated with soft-tissue sarcomas. Fusion proteins generated by such translocations often play critical roles in tumorigenesis. Therefore, it is important to understand the function of the fusion protein to develop therapeutic interventions. The t(X;18)(p11.2;q11.2) translocation found in synovial sarcomas results in a fusion between the SYT gene on chromosome 18 and an SSX gene on the X chromosome. Although SYT-SSX fusion proteins appear to trigger synovial sarcoma development, little is known about the downstream targets of SYT-SSX. We found that the SYT-SSX fusion protein produces a dominant-negative function for SYT, which is a transcriptional coactivator. We then analyzed the gene expression profiles of SYT-SSX1-expressing HeLa cells using oligonucleotide microarrays and found that the SYT-SSX1 fusion protein directly down-regulated the expression of COM1, a regulator of cell proliferation. COM1 was found to be expressed at relatively low levels in synovial sarcoma tissues and cell lines. We then investigated the impact of conditional COM1 expression in the synovial sarcoma cell line. Increased COM1 expression resulted in induced apoptosis and in reduced cell growth and colony formation activity. Our results suggested that restoration of COM1 expression may be of therapeutic benefit in synovial sarcoma.
authors.affiliation: Genter for Medical Genomics, Pathology Division, National Cancer Center Research Institute, 5-1-1 Tsukiji Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Ishida
authors.forename: Mamiko
authors.initials: M
authors.lastname: Miyamoto
authors.forename: Sayu
authors.initials: S
authors.lastname: Naitoh
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tatsuda
authors.forename: Tadashi
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nemoto
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yokozeki
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Nishioka
authors.forename: Akio
authors.initials: A
authors.lastname: Matsukage
authors.forename: Misao
authors.initials: M
authors.lastname: Ohki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Ohta
mesh_terms: D017209:Apoptosis; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D041321:Chromosomes, Human, X / Q000235:genetics*; D003114:Colony-Forming Units Assay; D015536:Down-Regulation / Q000235:genetics*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics*; D014411:Neoplastic Stem Cells; D015514:Oncogene Proteins, Fusion / Q000737:chemistry / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D013584:Sarcoma, Synovial / Q000235:genetics* / Q000473:pathology; D014178:Translocation, Genetic
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; C491643:NUPR1 protein, human; C116512:SYT-SSX fusion protein