De novo and acquired resistance, which are largely attributed to genetic alterations, are barriers to effective anti-epidermal-growth-factor-receptor (EGFR) therapy. To generate cetuximab-resistant cells, we exposed cetuximab-sensitive colorectal cancer cells to cetuximab in three-dimensional culture. Using whole-exome sequencing and transcriptional profiling, we found that the long non-coding RNA MIR100HG and two embedded microRNAs, miR-100 and miR-125b, were overexpressed in the absence of known genetic events linked to cetuximab resistance. MIR100HG, miR-100 and miR-125b overexpression was also observed in cetuximab-resistant colorectal cancer and head and neck squamous cell cancer cell lines and in tumors from colorectal cancer patients that progressed on cetuximab. miR-100 and miR-125b coordinately repressed five Wnt/β-catenin negative regulators, resulting in increased Wnt signaling, and Wnt inhibition in cetuximab-resistant cells restored cetuximab responsiveness. Our results describe a double-negative feedback loop between MIR100HG and the transcription factor GATA6, whereby GATA6 represses MIR100HG, but this repression is relieved by miR-125b targeting of GATA6. These findings identify a clinically actionable, epigenetic cause of cetuximab resistance.

中文翻译：

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lncRNA MIR100HG衍生的miR-100和miR-125b通过Wnt /β-catenin信号传导介导西妥昔单抗耐药。

从头和获得性耐药主要归因于遗传改变，是有效抗表皮生长因子受体（EGFR）治疗的障碍。为了产生抗西妥昔单抗的细胞，我们在三维培养中将对西妥昔单抗敏感的结直肠癌细胞暴露于西妥昔单抗。使用全外显子组测序和转录谱分析，我们发现在不存在与西妥昔单抗耐药相关的已知遗传事件的情况下，长的非编码RNA MIR100HG和两个嵌入的microRNA miR-100和miR-125b过度表达。在耐西妥昔单抗的结直肠癌和头颈部鳞状细胞癌细胞系以及在西妥昔单抗上进展的结直肠癌患者的肿瘤中也观察到MIR100HG，miR-100和miR-125b过表达。miR-100和miR-125b协同抑制五个Wnt /β-catenin负调节剂，导致Wnt信号增强，西妥昔单抗耐药细胞中的Wnt抑制作用恢复了西妥昔单抗的反应性。我们的结果描述了MIR100HG与转录因子GATA6之间的双负反馈环，从而GATA6抑制MIR100HG，但miR-125b靶向GATA6可缓解这种抑制。这些发现确定了西妥昔单抗耐药的临床上可行的表观遗传原因。