虽然黑色素瘤通常存在 CDKN2A 所在的 9p21 缺失，但该位点是否存在其他肿瘤抑制元件的特征尚不完全。在这里，我们评估了 microRNA-876-3p (miR-876) 的表达水平和功能作用，其基因也映射到 9p21。使用定量 miRNA 逆转录酶聚合酶链反应评估了 miR-876 在人体组织和细胞系中的表达（定量RT-PCR）。 MIR876 拷贝数是在癌症基因组图谱 (TCGA) 黑色素瘤队列中确定的。评估了 miR-876 表达调节对黑色素瘤细胞集落形成、迁移、侵袭、凋亡、细胞周期进展和培养物药物敏感性以及异种移植模型中体内肿瘤生长的影响。使用 RNA 测序 (RNA-Seq) 确定了 miR-876 过表达引起的全基因组转录组变化。与痣相比，原发性黑色素瘤样品中的 miR-876 表达显着降低，与人类黑色素细胞相比，人类黑色素瘤细胞系中的 miR-876 表达显着降低。 TCGA 队列分析显示，50% 以上的黑色素瘤中存在 MIR876 缺失。 miR-876 过表达导致黑色素瘤细胞集落形成、迁移和侵袭减少，并伴有细胞周期停滞和细胞凋亡增加。瘤内注射 miR-876 显着抑制体内黑色素瘤生长。对 miR-876 处理的肿瘤进行 RNA-Seq 分析，发现数个生长促进基因下调，同时抑癌基因上调，qRT-PCR 分析证实了这一点。计算分析确定 MAPK1（或 ERK2）是 miR-876 作用的可能靶标。 miR-876 的过表达显着抑制由 MAPK1/ERK2 3' UTR 驱动的荧光素酶表达，并导致黑色素瘤细胞中 ERK 蛋白表达降低。 MAPK1/ERK2 cDNA 过表达挽救了 miR-876 对黑色素瘤集落形成的影响。 miR-876 过表达使黑色素瘤细胞对 BRAF 抑制剂维莫非尼 (vemurafenib) 治疗敏感。这些研究将 miR-876 确定为 9p21 上的独特肿瘤抑制因子，在黑色素瘤中失活，并表明 miR-876 缺失是激活 ERK 和有丝分裂原激活的额外机制黑色素瘤中的蛋白激酶（MAPK）通路。此外，他们还提出将 miR-876 过度表达与 BRAF 抑制相结合作为黑色素瘤的合理治疗策略的治疗潜力。© 2024。作者。

While melanomas commonly harbor losses of 9p21, on which CDKN2A resides, the presence of additional tumor suppressor elements at this locus is incompletely characterized. Here we assess the expression levels and functional role of microRNA-876-3p (miR-876), whose gene also maps to 9p21.Expression of miR-876 was assessed in human tissues and cell lines using quantitative miRNA reverse transcriptase polymerase chain reaction (qRT-PCR). MIR876 copy number was determined in The Cancer Genome Atlas (TCGA) melanoma cohort. The consequences of regulation of miR-876 expression were assessed on melanoma cell colony formation, migration, invasion, apoptosis, cell cycle progression, and drug sensitivity in culture, and on in vivo tumor growth in a xenograft model. Genome-wide transcriptomic changes induced by miR-876 overexpression were determined using RNA sequencing (RNA-Seq).miR-876 expression was significantly decreased in primary melanoma samples when compared with nevi, and in human melanoma cell lines when compared with human melanocytes. Analysis of the TCGA cohort revealed deletions in MIR876 in > 50% of melanomas. miR-876 overexpression resulted in decreased melanoma cell colony formation, migration, and invasion, which was accompanied by cell cycle arrest and increased apoptosis. Intra-tumoral injections of miR-876 significantly suppressed melanoma growth in vivo. RNA-Seq analysis of miR-876-treated tumors revealed downregulation of several growth-promoting genes, along with upregulation of tumor suppressor genes, which was confirmed by qRT-PCR analysis. Computational analyses identified MAPK1 (or ERK2) as a possible target of miR-876 action. Overexpression of miR-876 significantly suppressed luciferase expression driven by the MAPK1/ERK2 3' UTR, and resulted in decreased ERK protein expression in melanoma cells. MAPK1/ERK2 cDNA overexpression rescued the effects of miR-876 on melanoma colony formation. miR-876 overexpression sensitized melanoma cells to treatment with the BRAF inhibitor vemurafenib.These studies identify miR-876 as a distinct tumor suppressor on 9p21 that is inactivated in melanoma and suggest miR-876 loss as an additional mechanism to activate ERK and the mitogen activated protein kinase (MAPK) pathway in melanoma. In addition, they suggest the therapeutic potential of combining miR-876 overexpression with BRAF inhibition as a rational therapeutic strategy for melanoma.© 2024. The Author(s).