基于核酸靶标免扩增CRISPR/Cas体系的分子速测技术研究进展

快速准确的分子诊断在食品安全、疾病诊断、环境监测等生命科学领域发挥重要作用。成簇规则间隔短回文重复序列(clustered regularly interspaced short palindromic repeats,CRISPR)及相关蛋白(CRISPR-associated protein,Cas)组成的CRISPR/Cas系统因具有高灵敏度、高特异性、便捷性及快速等优势,已成为精确检测核酸靶标的重要分子诊断工具。基于CRISPR/Cas系统的检测通过预扩增步骤提高靶标浓度,但也随之带来气溶胶污染、操作复杂和检测周期长等问题。因此需要积极开发更多免扩增策略,在最大限度保证灵敏度的同时,一步式实现对靶标的检测。综述了免扩增CRISPR系统的重要性,重点阐述了反应影响因素及相关策略对体系的优化作用,以及数字芯片法、表面增强拉曼光谱法和电化学金属电极法对信号放大效果的前沿进展,并对CRISPR/Cas系统的即时检测应用进行展望,以期为免扩增CRISPR/Cas检测系统的发展提供理论指导。

Human epidermal growth factor receptor-2 gene amplification in gastric cancer using tissue microarray technology

AIM:To assess human epidermal growth factor receptor-2 (HER2)-status in gastric cancer and matched lymph node metastases by immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH).METHODS:120 cases of primary gastric carcinomas and 45 matched lymph node metastases from patients with full clinicopathological features were mounted onto multiple-punch and single-punch tissue microarrays,respectively,and examined for HER2 overexpression and gene amplification by IHC and CISH.RESULTS:Twenty-four tumors (20%) expressed HER2 immunohistochemically.An IHC score of ≥ 2+ was observed in 20 tumors (16.6%).HER2 amplification was detected by CISH in 19 tumors (15.8%) and in their matched lymph node metastases.A high concordancerate was found between HER2 positivity (as detected by IHC) and HER2 gene amplification (as detected by CISH),since 19 of the 20 IHC positive cases were amplified (95%).All amplified cases had 2+ or 3+ IHC results.Amplification was associated with intestinal phenotype (P < 0.05).No association with grading,staging or survival was found.CONCLUSION:In gastric cancer,HER2 amplification is the main mechanism for HER2 protein overexpression and is preserved in lymph node metastases.