Owen Daniel R, Wong Hui-Li, Bonakdar Melika, Jones Martin, Hughes Christopher S, Morin Gregg B, Jones Steven J M, Renouf Daniel J, Lim Howard, Laskin Janessa, Marra Marco, Yip Stephen, Schaeffer David F
Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia V6T 2B5, Canada.
Department of Pathology & Laboratory Medicine, Vancouver General Hospital, Vancouver, British Columbia V5Z 1M9, Canada.
Cold Spring Harb Mol Case Stud. 2018 Apr 2;4(2). doi: 10.1101/mcs.a002535. Print 2018 Apr.
amplification has been identified in ∼5% of wild-type colorectal cancers (CRCs). A recent clinical trial showed response to HER2-directed therapy in a subset of -amplified metastatic CRCs resistant to chemotherapy and EGFR-directed therapy. With the aim of better understanding mechanisms of resistance to HER2-directed and EGFR-directed therapies, we report the complete molecular characterization of two cases of -amplified CRC. PCR-free whole-genome sequencing was used to identify mutations, copy-number alterations, structural variations, and losses of heterozygosity. copy number was also measured by fluorescence in situ hybridization. Single-stranded mRNA sequencing was used for gene expression profiling. Immunohistochemistry and protein mass spectrometry were used to quantify HER2 protein expression. The cases showed copy number of 86 and 92, respectively. Both cases were immunohistochemically positive for HER2 according to CRC-specific scoring criteria. Fluorescence in situ hybridization and protein mass spectrometry corroborated significantly elevated copy number and abundance of HER2 protein. Both cases were microsatellite stable and without mutation of RAS pathway genes. Additional findings included altered expression of , , and and mutation of The potential effects of the molecular alterations on sensitivity to EGFR and HER2-directed therapies were discussed. Identification of amplification in CRC is necessary to select patients who may respond to HER2-directed therapy. An improved understanding of the molecular characteristics of -amplified CRCs and their potential mechanisms of resistance will be useful for future research into targeted therapies and may eventually inform therapeutic decision-making.
在约5%的野生型结直肠癌（CRC）中已发现扩增现象。最近一项临床试验表明，在一部分对化疗和表皮生长因子受体（EGFR）靶向治疗耐药的扩增型转移性CRC中，患者对HER2靶向治疗有反应。为了更好地理解对HER2靶向治疗和EGFR靶向治疗的耐药机制，我们报告了两例扩增型CRC的完整分子特征。采用无PCR全基因组测序来识别突变、拷贝数改变、结构变异和杂合性缺失。还通过荧光原位杂交测量拷贝数。单链mRNA测序用于基因表达谱分析。免疫组织化学和蛋白质质谱用于量化HER2蛋白表达。这两例病例的拷贝数分别为86和92。根据CRC特异性评分标准，两例病例的HER2免疫组织化学均呈阳性。荧光原位杂交和蛋白质质谱证实了HER2拷贝数和蛋白丰度显著升高。两例病例均为微卫星稳定，且RAS通路基因无突变。其他发现包括、和的表达改变以及的突变。讨论了分子改变对EGFR和HER2靶向治疗敏感性的潜在影响。在CRC中鉴定扩增对于选择可能对HER2靶向治疗有反应的患者很有必要。更好地了解扩增型CRC的分子特征及其潜在耐药机制将有助于未来靶向治疗的研究，并最终可能为治疗决策提供参考。
