新分子标志物组合(DPP4、SCG5和CA12)在甲状腺癌术前诊断中的作用

Thyroid cancer is the most common endocrine tumor; more than 90% is differentiated thyroid cancer. Due to the lack of effective diagnosis of benign and malignant nodules and tumor invasion, some patients have been under excessive operation or inadequate treatment. Based on bioinformatics analysis, we had established a prediction model bases on three signature genes (DPP4, SCG5 and CA12) to predict thyroid carcinoma. The prediction accuracy ranged from 78.8% to 94.3% in three independent public dataset and thyroid tissue samples in Renji Hospital. However, the difference of expression level of the three-gene panel has not been studied. In addition, the previous study was based on tissue samples obtained after surgery. How is the prediction performance of the three-gene panel preoperatively by Fine-Needle Aspiration samples? Could the noninvasive prediction model based on the expression level of three proteins (DPP4, SCG5 and CA12) in serum contribute to the diagnosis of thyroid cancer? Therefore, we plan to evaluate the expression level of the three gene panel between invasive or noninvasive thyroid carcinoma and carry out prospective studies of thyroid cancer diagnosis with fine needle aspiration biopsy. In addition, for the reason that the three proteins encoded by DPP4, SCG5 and CA12 can be secreted into the peripheral blood, we could further study the noninvasive diagnostic model and finally provide valuable information for personalized treatment in patients with thyroid cancer.

甲状腺癌是最常见的内分泌肿瘤，但超过90%的结节为良性，因术前准确诊断结节良恶性尚存在困难造成过度手术，故临床急需术前确认结节良恶性的诊断指标。申请人前期通过生物信息学方法构建了以三个分子标志物组合(DPP4、SCG5和CA12)预测甲状腺癌的数学模型，其在公共数据库及临床标本中均有较高预测准确性(78.8%～94.3%)，但在不同侵袭力恶性结节中的表达情况尚未研究。另外，前期研究均基于术后组织标本，该预测模型是否可通过检测细针穿刺标本真正实现术前诊断？另外，DPP4、SCG5和CA12编码蛋白均可分泌到外周血，其在血清学无创诊断中的价值如何？为明确以上问题，本课题拟在完成不同侵袭力甲状腺癌术后组织标本中三个分子表达差异基础上，以细针穿刺标本开展前瞻性甲状腺癌诊断研究；进一步探索无创诊断模型，并建立预测性能更高的外周血蛋白表达和临床资料混合模型，最终为甲状腺癌患者个性化治疗提供有价值信息。

甲状腺癌是头颈部常见的恶性肿瘤，也近年来国内外人群中上升最快的肿瘤。值得注意的是甲状腺结节大部分为良性病变，而术前准确诊断结节的良、恶性尚存在一定困难。每年有相当一部分良性甲状腺肿瘤患者因术前无法得到明确诊断而进行了不必要的探查性手术，因此甲状腺肿瘤术前诊断过程中的关键是确定结节良、恶性，并对其中恶性结节的侵袭能力进行预判。申请人前期在公共数据库筛选了以三个分子标志物组合(DPP4、SCG5和CA12)预测甲状腺癌的数学模型，并在公共数据库进行验证，其预测准确性约78.8% ~ 94.3%。DPP4, SCG5和CA12三个蛋白均为分泌型蛋白，可在外周血中检测，因此申请者收集术前甲状腺肿瘤患者血清，以ELISA法进行检测发现血清中DPP4(均值：恶性组9138.433±11670.57，良性组3118.909±4752.403，P=0.009)与SCG5（均值：恶性组570.432±735.089，良性组142.502±256.090 ，P=0.003）含量在良恶性甲状腺结节中表达有显著差异，但血清CA12在良恶性甲状腺癌中无明显差异(P=0.299)。申请者同时对良性甲状腺结节、甲状腺乳头状癌淋巴结转移以及未转移组织样本各10例进行蛋白质谱分析，差异蛋白结果显示DPP4在甲状腺癌良恶性差异中排名第一，但其在甲状腺癌转移及未转移组中无差异。SCG5和CA12在良恶性甲状腺肿瘤以及甲状腺癌转移与未转移组中均无差异。对于甲状腺癌转移组与未转移组比较分析发现AGR2,GGH,MET,MMGT1,QKI, SERPINA7,SNAPIN,VPS36在恶性转移组中表达量明显高于其他组。此外，申请者采用ARMS法对2812例穿刺样本进行BRAFV600E突变检测发现，术前FNA细针穿刺学不同贝塞斯达系统中BRAF突变率也明显不同（p<0.001）：第2类即“良性”类突变率13.4%，而第5类“怀疑恶性”和第6类“恶性”突变率分别为79.5%和88.7%。第3类“不确定价值的不典型增生”，第4类“滤泡性肿瘤”BRAF突变率居中分别为45.63%和27.72%。因此，BRAF突变率随术前细胞穿刺学结果恶性程度增加而上升。综上所述，血清DPP4，SCG5以及细针穿刺BRAF突变检测在良恶性甲状腺肿瘤术前诊断模型中起重要作用，但不同侵袭性甲状腺癌危险度分层相关分子标志物尚需进一步研究。