恶性外周神经鞘瘤中XPO7-MYB融合基因的临床意义及其分子生物学机制

Malignant peripheral nerve sheath tumor (MPNST) is a relatively rare type of soft tissue sarcoma that lacks effective therapeutic strategies. By now there is no fusion gene reported in MPSNT, even plenty of studies have shown that MPNST exhibit lots of recurrent genetic aberrations that significantly alter multiple signaling pathways. In our preliminary study, transcriptome sequencing of two human MPSNT cell lines discovery the novel XPO7-MYB fusion gene in MPSNT. Reverse-transcript PCR (RT-PCR) and fluorescent in situ hybridization (FISH) methods were used and successfully validated the fusion event in MPSNT cell lines and small clinical MPSNT samples. The aim of this project is to investigate the possible clinical significance and biological mechanism of this novel XPO7-MYB fusion gene in MPNST. Firstly, RT-PCR and FISH methods were used to detect the recurrent frequency of XPO7-MYB fusion gene in 146 MPNST samples, with the purpose to investigate the clinical significance of this fusion event in MPSNT. Secondly, we would investigate the breakpoint, structure, biological function, and associated mechanism of this fusion gene in MPNST by whole genome sequencing, transcriptome sequencing, cell culture, gene transfection, microarray detection, and molecular biological experiments. These studies would throw light on the specific diagnosis and therapy targeting XPO7-MYB fusion gene in MPNST.

恶性外周神经鞘瘤（Malignant peripheral nerve sheath tumor, MPNST）是高度恶性的难治性软组织肉瘤。虽然在MPNST中发现大量的基因拷贝数异常及信号通路异常，但到目前为止没有融合基因的相关报道。在前期研究中我们对2个MPNST细胞系的转录组进行深度测序发现MPSNT中存在XPO7-MYB融合基因，并通过逆转录PCR（RT-PCR）及荧光原位杂交(FISH)的方法得到验证。本课题拟围绕前期发现的XPO7-MYB融合基因，首先在146例临床MPSNT样本中用RT-PCR及FISH的方法进行筛查，明确该融合基因的发生频率及其临床意义;再用全基因组/转录组深度测序、细胞培养、基因转染、芯片检测及质谱分析等方法探讨XPO7-MYB融合基因的结构、生物学功能及可能的分子机制，为MPNST中开展针对XPO7-MYB融合基因的特异性诊断及靶向治疗奠定基础。

恶性外周神经鞘瘤（Malignant peripheral nerve sheath tumor, MPNST）是高度恶性的软组织肉瘤，易出现复发及转移，预后很差。我们通过全基因组测序、细胞培养及分子生物学方法，发现：1. MPNST预后极差，5年生存率仅为40.2%，10年生存率为17.8%。2..人MPNST中无XPO7-MYB基因存在，但是c-MYB 蛋白高表达且是MPSNT无病生存和总生存的预后因子。3..EED及SUZ12基因的缺失是NF1阴性的散发性MPNST的频发事件。4.FGFRs家族基因在MPNST中存在遗传学异常，FGFR1基因拷贝数是增加的，而FGFR2和FGFR3基因的拷贝数是缺失的。FGFR1基因拷贝数呈片段扩增模式和倍体扩增模式，并且发现FGFR1蛋白的表达是MPNST的独立预后因素。FGFR4蛋白在恶性周围神经鞘膜瘤中是高表达的，且其表达是恶性周围神经鞘膜瘤无病生存期的预后因子。FGFRs在恶性周围神经鞘膜瘤中有着不同的预后作用。5. TBX2-CHK2-p53信号通路基因在MPNST中的存在突变，高表达TBX2、CHK2及p53组患者的预后较差。MPNST中TBX2-CHK2-p53通路的存在异常，可能通过提高Ki-67蛋白的表达来促进MPNST的增殖。TBX2及CHK2可能成为MPNST潜在的预后因素及靶向治疗靶点。这些研究说明MPNST为高度遗传变异性肿瘤，筛选的FGFR1、TBX2、CHK2、MYB等生物表达为提高MPNST的早期诊断、预后判断和提高疗效奠定了基础。该项目发表文章14篇，其中SCI文章9篇（大于5分的4篇），获省部级奖励2项，培养研究生3名。