microRNA205介导的细胞自噬在前庭神经鞘膜瘤囊性变中的作用机制研究

Vestibular schwannoma (VS) is the most common benign tumor in inner auditory canal and cerebellopontine angle. VS grows more rapidly and is more invasive after cystic degeneration, leading to serious symptoms and deteriorative conditions. Cystic degeneration of VS is a strong indication for surgery, however, effect is far from satisfactory. Therefore, it is important to reveal the mechanisms of cystic degeneration of VS. Our previous study screened the differentiated genes and microRNAs between cystic vestibular schwannoma (CVS) and solid vestibular schwannoma (SVS). We also found that miRNA205 promoted the rapid growth of CVS and inhibited autophagy by targeted mediation of PTEN/PI3K/AKT/mTOR pathway. Accordingly, we hypothesized that miRNA205-mediated cellular autophagy may result in cystic degeneration of VS. This research will carry out based on both cultured primary cells and established animal models to reveal the mechanisms of miRNA205, PTEN and autophagy in cystic degeneration of VS and its rapid growth through clinical analysis, vitro experiment and xenograft tumors on animal models; clarify the role of miRNA205 mediated autophagy in cystic degeneration of VS. This study will find the target on diagnosis and treatment of CVS, which will predict cystic degeneration of VS and provide strong support for targeted treatment of CVS.

前庭神经鞘膜瘤（VS）为内听道及桥小脑角最多见良性肿瘤，囊性变后肿瘤体积增大、症状加重、侵袭性更甚，手术指证强烈，但手术疗效不佳。因此，探究VS囊性变机制具有重要意义。课题组前期从基因组及转录组层面筛选出囊性（CVS）与实性前庭神经鞘膜瘤（SVS）中的差异表达基因及microRNA，并发现miRNA205通过靶向调控PTEN/PI3K/AKT/mTOR通路,促进CVS细胞快速增殖并抑制其细胞自噬，由此我们提出“miRNA205介导细胞自噬可能导致VS囊性变”的假说。本项目拟从分子、细胞及模式动物多层次展开，通过临床相关性研究/肿瘤细胞离体实验/异种移植瘤动物实验，揭示miRNA205、PTEN等关键分子以及自噬相关分子对CVS细胞快速增殖及VS囊性变的作用，明确miRNA205介导细胞自噬导致VS囊性变的机制，有效预测肿瘤囊性变，寻找VS囊性变的关键诊疗靶点，为CVS靶向治疗提供有力依据。

前庭神经鞘膜瘤（VS）是颅内良性肿瘤，囊性变后肿瘤体积增大、压迫症状加重、致聋速度及程度更明显、手术指证强烈但手术疗效不佳。探究VS囊性变发生发展及致聋机制，寻找药物治疗靶点，将对其诊疗效果产生重要意义。结合cDNA基因表达芯片技术和miRNA高通量测序，本课题组挖掘囊性（CVS）与实性前庭神经鞘膜瘤（SVS）中的差异表达基因及microRNA，从分子和细胞层次验证了miRNA-205可通过靶向作用CDK14并调控细胞增殖通路PTEN/PI3K/AKT/mTOR多个靶基因从而抑制CVS增殖。差速离心法从CVS和SVS原代细胞提取外泌体。通过小动物活体成像发现，经小鼠尾静脉注射的荧光外泌体在离体耳蜗有明显的信号表达，证明外泌体具有通过血液循环抵达耳蜗的可能。通过内耳注射技术进一步建立VS 外泌体致聋的动物模型，听觉电生理研究结果显示 CVS组小鼠的 ABR 阈值、DPOAE 阈值、Ⅰ波波幅都受到明显影响，提示毛细胞、带状突触、听神经功能障碍；耳蜗病理学结果证实了CVS外泌体具有耳毒性并呈浓度依赖性。本项目重点关注VS囊性变的可能作用机制，通过miRNA高通量测序从转录组层面解析导致实性与囊性前庭神经鞘膜瘤转录谱差异变化的关键调控分子，发现miRNA205通过调控靶基因PTEN影响CVS细胞增殖能力，并首次发现CVS具有耳毒性。上述研究为前庭神经鞘膜瘤囊性变机制的基础研究奠定重要基础，为寻找VS囊性变的关键诊疗靶点及CVS靶向治疗提供有力依据。