Gene expression profiling of human neuroblastoma BE(2)-C cells with MEIS2 depletion. Homo sapiens

MEIS2 has an important role in development and organogenesis, and is implicated in the pathogenesis of human cancer. The molecular basis of MEIS2 action in tumorigenesis is not clear. Here, we show that MEIS2 is highly expressed in human neuroblastoma cell lines and is required for neuroblastoma cell survival and proliferation. Depletion of MEIS2 in neuroblastoma cells leads to M phase arrest and mitotic catastrophe, whereas ectopic expression of MEIS2 markedly enhances neuroblastoma cell proliferation, anchorage-independent growth, and tumorigenicity. Gene expression profiling reveals an essential role of MEIS2 in maintaining the expression of a large number of late cell cycle genes, including those required for DNA replication, G2-M checkpoint control and M phase progression. Importantly, we identify MEIS2 as a transcription activator of the MuvB-BMYB-FOXM1 complex that functions as a master regulator of mitotic gene expression. Further, we show that FOXM1 is a direct target gene of MEIS2 and is required for MEIS2 to upregulate mitotic genes. These findings link a development gene to the control of cell cycle progression and suggest that high MEIS2 expression is a molecular mechanism for high expression of mitotic genes that is commonly observed in cancers of poor prognosis. Overall design: Affymetrix microarray assays were performed according to the manufacturer's directions on total RNA isolated from three independent samples of BE(2)-C cells infected with lentiviruses expressing either shGFP or shMEIS2-43 for 48 hours.

MEIS2在发育及器官发生过程中发挥关键作用，且与人类癌症的发病机制密切相关。目前，MEIS2在肿瘤发生中的分子调控基础仍不明确。本研究证实，MEIS2在人类神经母细胞瘤细胞系中高表达，且对神经母细胞瘤细胞的存活与增殖不可或缺。在神经母细胞瘤细胞中敲低MEIS2会引发M期阻滞与有丝分裂灾难（mitotic catastrophe），而过表达MEIS2则可显著增强神经母细胞瘤细胞的增殖能力、非锚定依赖性生长（anchorage-independent growth）以及致瘤性。基因表达谱分析（gene expression profiling）显示，MEIS2在维持大量晚期细胞周期基因的表达中具有核心作用，这些基因涵盖DNA复制、G2-M检验点（G2-M checkpoint）调控以及M期进程所需的相关基因。尤为重要的是，本研究鉴定出MEIS2是MuvB-BMYB-FOXM1复合物的转录激活因子（transcription activator），该复合物作为有丝分裂基因表达的核心调控因子发挥功能。进一步研究表明，FOXM1是MEIS2的直接靶基因（direct target gene），且是MEIS2上调有丝分裂基因表达所必需的。上述研究结果将发育相关基因与细胞周期进程调控建立了关联，并提示MEIS2高表达是预后不良癌症中普遍存在的有丝分裂基因高表达的分子机制。
整体实验设计：按照生产商的操作指南，对三组独立的BE(2)-C细胞样本的总RNA进行Affymetrix微阵列检测，这些细胞分别经携带shGFP或shMEIS2-43的慢病毒感染48小时后提取总RNA。