Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Wexner Medical Center, Columbus, OH 43210.
Proc Natl Acad Sci U S A. 2013 Nov 5;110(45):18208-13. doi: 10.1073/pnas.1315365110. Epub 2013 Oct 21.
miR-17∼92 is a polycistronic microRNA (miR) cluster (consisting of miR-17, miR-18a, miR-19a, miR-19b, miR-20a, and miR-92a) which frequently is overexpressed in several solid and lymphoid malignancies. Loss- and gain-of-function studies have revealed the role of miR-17∼92 in heart, lung, and B-cell development and in Myc-induced B-cell lymphomas, respectively. Recent studies indicate that overexpression of this locus leads to lymphoproliferation, but no experimental proof that dysregulation of this cluster causes B-cell lymphomas or leukemias is available. To determine whether miR-17∼92- overexpression induces lymphomagenesis/leukemogenesis, we generated a B-cell-specific transgenic mouse model with targeted overexpression of this cluster in B cells. The miR-17∼92 overexpression was driven by the Eµ-enhancer and Ig heavy-chain promoter, and a 3' GFP tag was added to the transgene to track the miR expression. Expression analysis using Northern Blot and quantitative RT-PCR confirmed 2.5- to 25-fold overexpression of all six miRs in the transgenic mice spleens as compared with spleens from wild-type mice. Eµ-miR-17∼92 mice developed B-cell malignancy by the age of 12-18 mo with a penetrance of ∼80% (49% splenic B-cell lymphoproliferative disease, 28% lymphoma). At this stage mice exhibited severe splenomegaly with abnormal B-cell-derived white pulp expansion and enlarged lymph nodes. Interestingly, we found three classes of B-cell lymphomas/leukemias at varying grades of differentiation. These included expansion of CD19(+) and CD5(+) double-positive B cells similar to the aggressive form of human B-cell chronic lymphocytic leukemia, B220(+) CD43(+) B1-cell proliferation, and a CD19(+) aggressive diffuse large B-cell lymphoma-like disease, as assessed by flow cytometry and histopathological analysis.
miR-17∼92 是一个多顺反子 microRNA（miRNA）簇（由 miR-17、miR-18a、miR-19a、miR-19b、miR-20a 和 miR-92a 组成），在几种实体瘤和淋巴恶性肿瘤中经常过度表达。失活和功能获得研究表明，miR-17∼92 在心脏、肺和 B 细胞发育以及 Myc 诱导的 B 细胞淋巴瘤中分别发挥作用。最近的研究表明，该基因座的过表达导致淋巴增生，但尚无实验证据表明该簇的失调会导致 B 细胞淋巴瘤或白血病。为了确定 miR-17∼92 的过表达是否诱导淋巴瘤/白血病发生，我们生成了一种 B 细胞特异性转基因小鼠模型，该模型在 B 细胞中靶向过表达该簇。miR-17∼92 的过表达由 Eµ-增强子和 Ig 重链启动子驱动，并在转基因中添加了一个 3' GFP 标签以追踪 miR 的表达。使用 Northern Blot 和定量 RT-PCR 进行的表达分析证实，与野生型小鼠相比，转基因小鼠脾脏中所有六种 miRNA 的表达均过表达 2.5 至 25 倍。Eµ-miR-17∼92 小鼠在 12-18 月龄时发展为 B 细胞恶性肿瘤，其外显率约为 80%（49%的脾 B 细胞淋巴增生性疾病，28%的淋巴瘤）。在这个阶段，小鼠表现出严重的脾肿大，伴有异常的 B 细胞来源的白髓扩张和淋巴结肿大。有趣的是，我们在不同分化程度下发现了三类 B 细胞淋巴瘤/白血病。这些包括类似侵袭性人类 B 细胞慢性淋巴细胞白血病的 CD19(+)和 CD5(+)双阳性 B 细胞的扩增、B220(+)CD43(+)B1 细胞增殖以及 CD19(+)侵袭性弥漫性大 B 细胞淋巴瘤样疾病，如流式细胞术和组织病理学分析所示。
