Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer. The dismal outcome of ICC patients is due to lack of early diagnosis, the aggressive biological behavior of ICC and the lack of effective therapeutic options. Early diagnosis and prognosis of ICC by non-invasive methods would be helpful in providing valuable information and developing effective treatment strategies. Expression of microfibrillar-associated protein 5 (MFAP5) in the serum of ICC patients was detected by ELISA. Human ICC specimens were immunostained by MFAP5 antibodies. The growth rate of human ICC cell lines treated with MFAP5 or MFAP5 shRNAs was examined by CCK8 and colony formation assays. Cell cycle analysis was performed with PI staining. The effect of MFAP5 inhibition was assessed by xenograft models in nude mice. RNA-seq and ATAC-seq analyses were used to dissect the molecular mechanism by which MFAP5 promoted ICC aggressiveness. We identified MFAP5 as a biomarker for the diagnosis and prognosis of ICC. Upregulated MFAP5 is a common feature in aggressive ICC patients’ tissues. Importantly, MFAP5 level in the serum of ICC patients and healthy individuals showed significant differential expression profiles. Furthermore, we showed that MFAP5 promoted ICC cell growth and G1 to S-phase transition. Using RNA-seq expression and ATAC-seq chromatin accessibility profiling of ICC cells with suppressed MFAP5 secretion, we showed that MFAP5 regulated the expression of genes involved in the Notch1 signaling pathway. Furthermore, FLI-06, a Notch signaling inhibitor, completely abolished the MFAP5-dependent transcriptional programs. Raised MFAP5 serum level is useful for differentiating ICC patients from healthy individuals, and could be helpful in ICC diagnosis, prognosis and therapies.

中文翻译：

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MFAP5通过激活Notch1信号通路促进肝内胆管癌的侵袭性。

肝内胆管癌（ICC）是第二大最常见的原发性肝癌。ICC患者的预后不良是由于缺乏早期诊断，ICC具有侵略性的生物学行为以及缺乏有效的治疗选择。通过非侵入性方法对ICC进行早期诊断和预后将有助于提供有价值的信息和制定有效的治疗策略。通过ELISA检测ICC患者血清中微纤维相关蛋白5（MFAP5）的表达。用MFAP5抗体对人ICC标本进行免疫染色。通过CCK8和集落形成测定法检查了用MFAP5或MFAP5 shRNA处理的人ICC细胞系的生长速率。用PI染色进行细胞周期分析。通过异种移植模型在裸鼠中评估MFAP5抑制作用。RNA-seq和ATAC-seq分析用于剖析MFAP5促进ICC侵袭性的分子机制。我们确定MFAP5为ICC的诊断和预后的生物标志物。MFAP5上调是侵略性ICC患者组织的常见特征。重要的是，ICC患者和健康个体血清中的MFAP5水平显示出明显的差异表达谱。此外，我们表明MFAP5促进了ICC细胞的生长和G1到S期的转变。使用抑制MFAP5分泌的ICC细胞的RNA-seq表达和ATAC-seq染色质可及性分析，我们表明MFAP5调节了Notch1信号通路中涉及的基因的表达。此外，Notch信号抑制剂FLI-06完全废除了依赖MFAP5的转录程序。