Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada.
Department of Pathology, University Health Network, Toronto, Canada.
Lab Invest. 2018 Apr;98(4):403-413. doi: 10.1038/s41374-017-0007-2. Epub 2018 Jan 16.
A variety of laboratory methods are available for the detection of deletions of tumor suppressor genes and losses of their proteins. The clinical utility of fluorescence in situ hybridization (FISH) for the identification of deletions of tumor suppressor genes has previously been limited by difficulties in the interpretation of FISH signal patterns. The first deletion FISH assays using formalin-fixed paraffin-embedded tissue sections had to deal with a significant background level of signal losses affecting nuclei that are truncated by the cutting process of slide preparation. Recently, more efficient probe designs, incorporating probes adjacent to the tumor suppressor gene of interest, have increased the accuracy of FISH deletion assays so that true chromosomal deletions can be readily distinguished from the false signal losses caused by sectioning artifacts. This mini-review discusses the importance of recurrent tumor suppressor gene deletions in human cancer and reviews the common FISH methods being used to detect the genomic losses encountered in clinical specimens. The use of new probe designs to recognize truncation artifacts is illustrated with a four-color PTEN FISH set optimized for prostate cancer tissue sections. Data are presented to show that when section thickness is reduced, the frequency of signal truncation losses is increased. We also provide some general guidelines that will help pathologists and cytogeneticists run routine deletion FISH assays and recognize sectioning artifacts. Finally, we summarize how recently developed sequence-based approaches are being used to identify recurrent deletions using small DNA samples from tumors.
有多种实验室方法可用于检测肿瘤抑制基因缺失和其蛋白丢失。荧光原位杂交（FISH）用于识别肿瘤抑制基因缺失的临床应用以前受到 FISH 信号模式解释困难的限制。首次使用福尔马林固定石蜡包埋组织切片的缺失 FISH 检测必须处理由切片制备过程中截断核而导致的显著背景信号丢失水平。最近，更有效的探针设计，将探针与感兴趣的肿瘤抑制基因相邻，提高了 FISH 缺失检测的准确性，使得真正的染色体缺失可以很容易地区分与切片伪影引起的虚假信号丢失。这篇迷你综述讨论了人类癌症中复发性肿瘤抑制基因缺失的重要性，并回顾了用于检测临床标本中遇到的基因组缺失的常用 FISH 方法。使用新的探针设计来识别截断伪影的方法用优化的前列腺癌组织切片四色 PTEN FISH 试剂盒进行了说明。提供的数据表明，当切片厚度减小时，信号截断丢失的频率会增加。我们还提供了一些一般准则，将帮助病理学家和细胞遗传学家进行常规缺失 FISH 检测并识别切片伪影。最后，我们总结了最近开发的基于序列的方法如何使用来自肿瘤的小 DNA 样本来识别复发性缺失。
