OBJECTIVE: Middle ear cholesteatoma is a non-tumorous condition that typically leads to hearing loss, bone destruction, and other severe complications. Despite surgery being the primary treatment, the recurrence rate remains high. Therefore, exploring the molecular mechanisms underlying cholesteatoma is crucial for discovering new therapeutic approaches. This study aims to explore the involvement of N6-methyladenosine (m6A) methylation in long non-coding RNAs (lncRNAs) in the biological functions and related pathways of middle ear cholesteatoma.
METHODS: The m6A modification patterns of lncRNA in middle ear cholesteatoma tissues (n=5) and normal post-auricular skin tissues (n=5) were analyzed using an lncRNA m6A transcriptome microarray. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were conducted to identify potential biological functions and signaling pathways involved in the pathogenesis of middle ear cholesteatoma. Methylated RNA immunoprecipitation (MeRIP)-PCR was used to validate the m6A modifications in cholesteatoma and normal skin tissues.
RESULTS: Compared with normal skin tissues, 1 525 lncRNAs were differentially methylated in middle ear cholesteatoma tissues, with 1 048 showing hypermethylation and 477 showing hypomethylation [fold change (FC)≥3 or <1/3, P<0.05]. GO enrichment analysis indicated that hypermethylated lncRNAs were involved in protein phosphatase inhibitor activity, neuron-neuron synapse, and regulation of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor activity. Hypomethylated lncRNAs were associated with mRNA methyltransferase activity, secretory granule membrane, and mRNA methylation. KEGG analysis revealed that hypermethylated lncRNAs were mainly associated with 5 pathways: the Hedgehog signaling pathway, viral protein interaction with cytokines and cytokine receptors, mitogen-activated protein kinase (MAPK) signaling pathway, cytokine-cytokine receptor interaction, and adrenergic signaling in cardiomyocytes. Hypomethylated lncRNAs were mainly involved in 4 pathways: Renal cell carcinoma, tumor necrosis factor signaling pathway, transcriptional misregulation in cancer, and cytokine-cytokine receptor interaction. Additionally, MeRIP-PCR confirmed the changes in m6A methylation levels in NR_033339, NR_122111, NR_130744, and NR_026800, consistent with microarray analysis. Real-time PCR also confirmed the significant upregulation of MAPK1 and NF-κB, key genes in the MAPK signaling pathway.
CONCLUSIONS: This study reveals the m6A modification patterns of lncRNAs in middle ear cholesteatoma, suggests a direction for further research into the role of lncRNA m6A modification in the etiology of cholesteatoma. The findings provide potential therapeutic targets for the treatment of middle ear cholesteatoma.
目的: 中耳胆脂瘤是一种非肿瘤性疾病,通常会引起听力丧失、骨质破坏和其他严重并发症。尽管手术是主要的治疗方法,但其复发率较高。因此,探讨胆脂瘤的分子机制对寻找新的治疗方法具有重要意义。本文旨在探究长链非编码RNA(long non-coding RNA,lncRNA)中N6-甲基腺嘌呤(N6-methyladenosine,m6A)甲基化参与中耳胆脂瘤的生物学功能及相关通路。方法: 利用lncRNA m6A转录组芯片分析中耳胆脂瘤组织(n=5)和正常耳后皮肤组织(n=5)的m6A修饰模式。采用基因本体(Gene Ontology,GO)和京都基因与基因组数据库(Kyoto Encyclopedia of Genes and Genomes,KEGG)途径分析中耳胆脂瘤发病的可能生物学功能和信号通路。并运用甲基化RNA免疫沉淀(methylated RNA immunoprecipitation,MeRIP)-PCR验证中耳胆脂瘤和正常皮肤组织中的lncRNA m6A修饰。结果: 与正常皮肤对照组相比,中耳胆脂瘤组织中m6A甲基化修饰了1 525个lncRNAs(高甲基化1 048个,低甲基化477个),差异有统计学意义[差异倍数(fold change,FC)≥3或<1/3,P<0.05]。GO富集分析表明:高甲基化的lncRNA参与蛋白磷酸酶抑制剂活性、神经元间突触和α-氨基-3-羟基-5-甲基-4-异恶唑丙酸(α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid,AMPA)受体活性的调节。低甲基化lncRNA参与mRNA甲基转移酶活性、分泌颗粒膜和mRNA甲基化。KEGG分析表明:高甲基化lncRNAs主要与5条通路相关,包括Hedgehog信号通路、病毒蛋白与细胞因子及细胞因子受体的相互作用、丝裂原活化蛋白激酶(mitogen-activated protein kinases,MAPK)信号通路、细胞因子-细胞因子受体相互作用和心肌细胞的肾上腺素能信号通路。低甲基化lncRNA主要与4种途径相关:肾细胞癌、肿瘤坏死因子信号通路、癌症的转录失调以及细胞因子-细胞因子受体相互作用。此外,通过MeRIP-PCR验证了NR_033339、NR_122111、NR_130744和NR_026800中m6A甲基化水平的改变,与微距阵分析相一致。并且通过real-time PCR验证了MAPK信号通路的关键基因MAPK1和NF-κB表达量显著上调。结论: 本研究揭示了中耳胆脂瘤中lncRNA的m6A修饰模式,提示lncRNA m6A修饰在胆脂瘤病因学中的研究方向,为中耳胆脂瘤的治疗提供了潜在的靶点。.