Triple-negative breast cancer (TNBC) is a heterogeneous group of breast cancer and is characterized by aggressiveness and poor prognosis. MicroRNA represents a new class of biomarkers, and accumulating evidence indicates that microRNAs contribute to tumorigenesis and cancer metastasis. It has been described that miR-210 is highly expressed in TNBC, and its overexpression had been linked to poor prognosis. In a previous work, we showed that in TNBC miR-210 is expressed in tumor cells and also in the tumor microenvironment (TME), particularly in inflammatory CD45-LCA positive cells. However, the exact identity of these cells remained unknown. In this study, we performed in situ hybridization and immunohistochemistry using validated antibodies for the different specific immune cell markers on adjacent sections of 23 TNBC infiltrated with immune cells. We found that miR-210 expressing cells in the TME were stained positive with CD79a, a B-cell lineage marker. These tumor-infiltrating cells were negative for CD20 and Ki-67 but positive for MUM1 and CD38 and also expressed immunoglobulins, indicating that they are immunoglobulin-producing plasma cells (PCs). To the best of our knowledge, this is the first study demonstrating miR-210 expression in tumor-infiltrating PCs.

中文翻译：

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MiR-210在三阴性乳腺癌的肿瘤浸润浆细胞中过表达。

三阴性乳腺癌（TNBC）是一组异质性乳腺癌，其特征是侵袭性强且预后差。MicroRNA代表了一类新的生物标志物，越来越多的证据表明MicroRNA有助于肿瘤发生和癌症转移。据描述，miR-210在TNBC中高表达，其过表达与不良预后有关。在以前的工作中，我们表明miR-210在TNBC中表达于肿瘤细胞以及肿瘤微环境（TME）中，特别是在炎性CD45-LCA阳性细胞中表达。但是，这些细胞的确切身份仍然未知。在这项研究中，我们使用经过验证的针对不同免疫细胞标记物的抗体进行了原位杂交和免疫组织化学分析，该抗体在23个TNBC浸润了免疫细胞的相邻切片上。我们发现，TME中表达miR-210的细胞被CD79a（一种B细胞谱系标记）染色为阳性。这些肿瘤浸润细胞的CD20和Ki-67阴性，而MUM1和CD38阳性，并且还表达免疫球蛋白，表明它们是产生免疫球蛋白的浆细胞（PC）。据我们所知，这是第一个证明miR-210在肿瘤浸润PC中表达的研究。