Amemiya Kenji, Hirotsu Yosuke, Goto Taichiro, Nakagomi Hiroshi, Mochizuki Hitoshi, Oyama Toshio, Omata Masao
Genome Analysis Center, Yamanashi Prefectural Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, 400-8506, Japan.
Pathology Division, Laboratory Department, Yamanashi Prefectural Central Hospital, 1-1-1 Fujimi, Kofu, Yamanashi, 400-8506, Japan.
Cancer Med. 2016 Dec;5(12):3426-3436. doi: 10.1002/cam4.950. Epub 2016 Oct 24.
Identifying genetic alterations in tumors is critical for molecular targeting of therapy. In the clinical setting, formalin-fixed paraffin-embedded (FFPE) tissue is usually employed for genetic analysis. However, DNA extracted from FFPE tissue is often not suitable for analysis because of its low levels and poor quality. Additionally, FFPE sample preparation is time-consuming. To provide early treatment for cancer patients, a more rapid and robust method is required for precision medicine. We present a simple method for genetic analysis, called touch imprint cytology combined with massively paralleled sequencing (touch imprint cytology [TIC]-seq), to detect somatic mutations in tumors. We prepared FFPE tissues and TIC specimens from tumors in nine lung cancer patients and one patient with breast cancer. We found that the quality and quantity of TIC DNA was higher than that of FFPE DNA, which requires microdissection to enrich DNA from target tissues. Targeted sequencing using a next-generation sequencer obtained sufficient sequence data using TIC DNA. Most (92%) somatic mutations in lung primary tumors were found to be consistent between TIC and FFPE DNA. We also applied TIC DNA to primary and metastatic tumor tissues to analyze tumor heterogeneity in a breast cancer patient, and showed that common and distinct mutations among primary and metastatic sites could be classified into two distinct histological subtypes. TIC-seq is an alternative and feasible method to analyze genomic alterations in tumors by simply touching the cut surface of specimens to slides.
识别肿瘤中的基因改变对于治疗的分子靶向至关重要。在临床环境中，福尔马林固定石蜡包埋（FFPE）组织通常用于基因分析。然而，从FFPE组织中提取的DNA由于其含量低和质量差，往往不适合进行分析。此外，FFPE样本制备耗时。为了给癌症患者提供早期治疗，精准医学需要一种更快速、更可靠的方法。我们提出了一种简单的基因分析方法，称为触摸印记细胞学结合大规模平行测序（触摸印记细胞学 [TIC]-seq），用于检测肿瘤中的体细胞突变。我们从9名肺癌患者和1名乳腺癌患者的肿瘤中制备了FFPE组织和TIC标本。我们发现，TIC DNA的质量和数量高于FFPE DNA，后者需要显微切割从靶组织中富集DNA。使用下一代测序仪进行靶向测序，利用TIC DNA获得了足够的序列数据。发现肺原发性肿瘤中大多数（92%）体细胞突变在TIC和FFPE DNA之间是一致的。我们还将TIC DNA应用于原发性和转移性肿瘤组织，以分析一名乳腺癌患者的肿瘤异质性，并表明原发性和转移部位之间的常见和独特突变可分为两种不同的组织学亚型。TIC-seq是一种通过简单地将标本的切割表面接触载玻片来分析肿瘤基因组改变的替代且可行的方法。
