*Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Japan.
J Thorac Oncol. 2011 Oct;6(10):1677-86. doi: 10.1097/JTO.0b013e3182286d25.
A subset of lung cancers harbors an EML4-ALK (echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase) gene fusion, and detecting this subset may hold therapeutic implications. Many prior studies used fluorescence in situ hybridization (FISH) analysis for this detection, but FISH may have disadvantages including signal decay and dark-field examination that may obscure tissue architecture. In this study, we explored the potential of the ALK-break-apart chromogenic in situ hybridization (CISH) method to detect ALK-rearranged lung cancer.
We examined 15 lung adenocarcinomas with reverse-transcriptase polymerase chain reaction-proven EML4-ALK fusion transcripts and 30 ALK-negative cases. One hundred tumor cells were evaluated by CISH and FISH for each case, and a detailed signal profile was recorded and compared.
CISH preserved tissue architecture and cytomorphology considerably and facilitated the signal evaluation using a routine light microscope. Positive rearrangement signals (splits or isolated 3' signals) were identified in 13 to 78% (mean ± SD, 41% ± 19%) of tumor cells in the ALK-positive cohort and in 0 to 15% (mean ± SD, 6% ± 4%) of cells in the ALK-negative cohort. The two groups were best separated by a cutoff value of 20%, with a sensitivity of 93% and a specificity of 100%. The only false-negative tumor having only 13% CISH-positive cells displayed predominantly (76%) isolated 5' signals unaccompanied by 3' signals. FISH showed largely similar signal profiles, and the results were completely concordant with CISH.
We have successfully introduced CISH for diagnosing EML4-ALK-positive lung adenocarcinoma. This method allows simultaneous visualization of genetics and tumor cytomorphology and facilitates the molecular evaluation and could be applicable in clinical practice to detect lung cancer that may be responsive to ALK inhibitors.
一小部分肺癌存在 EML4-ALK（棘皮动物微管相关蛋白样 4-间变性淋巴瘤激酶）基因融合，检测这一小部分可能具有治疗意义。许多先前的研究使用荧光原位杂交（FISH）分析来进行这种检测，但 FISH 可能存在一些缺点，包括信号衰减和暗场检查，这可能会使组织结构变得模糊。在这项研究中，我们探索了 ALK 分离显色原位杂交（CISH）方法检测 ALK 重排肺癌的潜力。
我们检查了 15 例经逆转录酶聚合酶链反应证实存在 EML4-ALK 融合转录本的肺腺癌和 30 例 ALK 阴性病例。对每个病例的 100 个肿瘤细胞进行 CISH 和 FISH 检测，并记录和比较详细的信号谱。
CISH 极大地保留了组织结构和细胞形态学，并且可以通过常规显微镜方便地进行信号评估。在 ALK 阳性组中，13%至 78%（平均值±标准差，41%±19%）的肿瘤细胞中检测到阳性重排信号（分裂或孤立的 3'信号），而在 ALK 阴性组中，0 至 15%（平均值±标准差，6%±4%）的细胞中检测到阳性重排信号。将截断值设定为 20%时，两组之间的分离效果最佳，其敏感性为 93%，特异性为 100%。唯一的假阴性肿瘤仅 13%的 CISH 阳性细胞，主要表现为（76%）孤立的 5'信号，而没有 3'信号。FISH 显示出大致相似的信号谱，并且结果与 CISH 完全一致。
我们已经成功地引入 CISH 来诊断 EML4-ALK 阳性肺腺癌。这种方法允许同时观察遗传学和肿瘤细胞形态学，并有助于进行分子评估，并且可以在临床上应用于检测可能对 ALK 抑制剂有反应的肺癌。
