基于窄带成像技术的鼻咽癌放疗敏感性研究及分子机制探讨

Radiotherapy is the primary treatment for nasopharyngeal carcinoma (NPC), radioresistance remains a major obstacle to successful treatment in NPC. At present, it lacks of simple and effective tools to predict the radiosensitivity of NPC. Nasopharyngoscopy is a routine examination before radiotherapy. Recently, an optical image enhancement technology, narrow band imaging (NBI), combined with conventional white light endoscopic system was introduced to the examination of nasopharynx. NBI could display the detailed morphologic findings of nasopharyngeal epithelial microvessels, which had an important role for the NPC diagnosis, first reported by our previous studies. On the other hand, we found that the appearance of superficial microvessel detected by NBI endoscopy had a connection with radiosensitivity of NPC, which might become a simple method to predict the radiosensitivity. This hasn't been reported at home and abroad. This study intends to make an in-depth research for this phenomenon. The purposes of this study are to elucidate the value of novel tumor microvessles in the predicting the radiosensitivity, to identify the radiosensitive associated miRNA biomarkers, to found a combinded predicting model based on NBI scores and miRNA biomarkers, to interpret targets genes of the key miRNAs and its biological effect and pathway. The goal of this study is to establish a connection between tumor microvessel morphology and radiobiology, which could be used to predict the radiosensitivity and provide the help for the personalised treatment of NPC.

放疗是鼻咽癌首选的治疗手段，放疗抗拒是制约鼻咽癌疗效和预后的瓶颈。目前临床上缺乏简单、有效的放疗敏感性预测方法。鼻咽镜检查是鼻咽癌放疗前一项常规检查，最近出现的窄带成像（NBI）内镜系统能够对肿瘤组织表面新生微血管形态清晰显示，前期研究首先报道了鼻咽癌黏膜表面出现特异性新生血管，对鼻咽癌有较高的诊断价值，并且观察到肿瘤组织表面新生微血管显露与放疗敏感性有关联，可能是预测鼻咽癌放疗敏感性的一种简便手段，国内外未见相关报道。本研究拟对这一现象进行深入研究，探讨肿瘤组织表面微血管形态在预测鼻咽癌放疗敏感性方面的价值，鉴定鼻咽癌放疗敏感性相关miRNA分子标志物，建立基于NBI分级和miRNAs标志物的鼻咽癌放疗敏感性联合预测模型，明确关键miRNAs调控的靶基因及其生物学效应，由此建立一个由肿瘤形态学反映肿瘤放射生物学特性的桥梁，实现用简便方法预测鼻咽癌放疗敏感性，为鼻咽癌的个体化治疗提供帮助。

鼻咽癌约80%发生在中国，由于鼻咽癌对放射线具有较高的敏感性，放疗是目前鼻咽癌首选的治疗手段，但目前临床上缺乏简单、有效的放疗敏感性预测方法。鼻咽镜检查是鼻咽癌放疗前一项常规检查，最近出现的窄带成像（NBI）内镜系统能够对肿瘤组织表面新生微血管形态清晰显示，对鼻咽癌有较高的诊断价值。本研究根据NBI模式下鼻咽部不同性质病变的黏膜表面微血管形态学特点，确定了I-V型NBI的血管分型标准，发现79.5%（167/210）的鼻咽癌出现V型的血管表现，V型对鼻咽癌诊断的敏感性、特异性、阳性预测值和阴性预测值分别为79.5%、89.7%、95.4%和61.9%。将NBI内镜下鼻咽癌黏膜表面肿瘤新生微血管根据微血管显露的百分比分为1~4级，随诊观察鼻咽癌放射治疗50Gy后肿瘤组织的消退情况，总结了200例鼻咽癌组织NBI内镜下观察到的血管显露情况与鼻咽癌放疗消退情况之间的相关性，发现二者之间有明显的正相关性（P=0.006，x2=19.268）。进一步分别在10例放疗高敏感和10例放疗低敏感的鼻咽癌患者肿瘤及癌旁活检组织中使用miRNA芯片比较了鼻咽癌组织中差异表达miRNA，筛选出41个特异性地与鼻咽癌放疗敏感性相关的差异表达miRNA。在20个不同放疗敏感性的鼻咽癌活检组织中进行转录组测序，发现与血管生成相关的分子标记、PI3K途径及P450代谢途径与鼻咽癌的放疗敏感性密切相关。选取测序结果中差别最明显的相关基因进行验证，发现在血管显露组和放疗高敏感性组中紧密连接蛋白18（claudin-18）和磷酸肌醇酯-3-激酶β催化亚单位（PIK3CB）均有明显的高表达，钙调磷酸酶B同源蛋白2（CHP2）和细胞色素P450（CYP）4F22均有明显的低表达。这些标志分子在调控黏膜的血管显露和肿瘤的放疗敏感性方面均有一定的作用，可能是参与鼻咽癌放疗敏感性的关键分子，相关的分子生物学功能需要进一步进行验证。