ANALYSIS OF ABNORMAL GENES ASSOCIATED WITH SYNOVIAL SARCOMA ONCOGENESIS.

染色体易位t (X; 18)（p11.2; q11.2）在95%以上的滑膜肉瘤中被发现。18q11上SYT基因的近端部分与xp11、SSX1和SSX2两个重复基因之一的远端部分融合。SYT-SSX嵌合基因被认为与滑膜肉瘤的发生密切相关。该嵌合基因的检测有助于滑膜肉瘤的病理诊断。我们从常规处理的滑膜肉瘤病例的细胞学和组织学标本中提取RNA，并使用高灵敏度的RT-PCR在90%以上的病例中检测到SYT-SSX嵌合转录物。下一步，我们将研究SSX型参与SYT-SSX融合的临床病理意义。手术时无远处转移的滑膜肉瘤病例也包括在内。确定每个病例涉及的SSX型，然后观察组织学类型、有丝分裂图、预后和以下蛋白的表达；细胞周期相关蛋白Ki67和p27，以及凋亡相关蛋白p53和bcl-2。SYT-SSX1融合与Ki67的高表达和有丝分裂数字的增加有关，但与其他因素无关。在临床上，SYT-SSX1、有丝分裂数字和Ki67的表达是导致无病生存恶化的重要因素。我们对SYT-SSX融合蛋白促进细胞增殖的机制很感兴趣。由于SYT-SSX融合蛋白不具有明显的dna或rna结合结构域，因此融合蛋白可能与调节细胞周期的未知蛋白结合。我们通过双杂交系统将SYT-SSX融合基因转染酵母，发现了一些候选蛋白，并正在研究这些蛋白在滑膜肉瘤肿瘤发生中的意义。

Chromosome translocation t (X ; 18)(p11.2 ; q11.2) has been detected in more than 95% of the synovial sarcomas. The proximal portion of the SYT gene at 18q11 is fused the distal portion of one of two duplicated genes atXp11, SSX1 and SSX2. This SYT-SSX chimeric gene is considered to be closely associated with synovial sarcoma oncogenesis. Detection of this chimeric gene is useful in pathological diagnosis of synovial sarcoma. We extracted RNA from routinely-processed cytological and histological specimens of synovial sarcoma cases and detected SYT-SSX chimeric transcript in more than 90% of the cases using highly sensitive RT-PCR.In the next step, we studied the clinicopathological significance of the SSX type involved in the SYT-SSX fusion. Synovial sarcoma cases that had no distant metastasis at surgery were included. The SSX type involved in each case was confirmed, then, histological type, mitotic figures, prognosis, and expression of following proteins were investigated ; cell cycle-associated proteins, Ki67 and p27, and apoptosis-associated proteins, p53 and bcl-2. SYT-SSX1 fusion was associated with high expression of Ki67 and increased mitotic figures, but not with other factors. Clinically, SYT-SSX1, mitotic figures, and Ki67 expression were important factors for worse disease-free survival. We are interested in the mechanism by which SYT-SSX fusion proteins promote cell proliferation. Bacause SYT-SSX fusion protein does not possess apparent DNA-or RNA-binding domains, the fusion protein may bind to unknown proteins that would regulate cell cycling. We have found some candidate proteins by Two-hybrid system using SYT-SSX fusion gene transfection into yeast, and are studying the significance of these proteins in synovial sarcoma oncogenesis.