Rauschert Ines, Aldunate Fabian, Preussner Jens, Arocena-Sutz Miguel, Peraza Vanina, Looso Mario, Benech Juan C, Agrelo Ruben
Laboratory of Cellular Signaling and Nanobiology, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
Epigenetics of Cancer and Aging Laboratory, Institut Pasteur de Montevideo, Montevideo, Uruguay.
PLoS One. 2017 Apr 19;12(4):e0175953. doi: 10.1371/journal.pone.0175953. eCollection 2017.
Nuclear lamins support the nuclear envelope and provide anchorage sites for chromatin. They are involved in DNA synthesis, transcription, and replication. It has previously been reported that the lack of Lamin A/C expression in lymphoma and leukaemia is due to CpG island promoter hypermethylation. Here, we provide evidence that Lamin A/C is silenced via this mechanism in a subset of neuroblastoma cells. Moreover, Lamin A/C expression can be restored with a demethylating agent. Importantly, Lamin A/C reintroduction reduced cell growth kinetics and impaired migration, invasion, and anchorage-independent cell growth. Cytoskeletal restructuring was also induced. In addition, the introduction of lamin Δ50, known as Progerin, caused senescence in these neuroblastoma cells. These cells were stiffer and developed a cytoskeletal structure that differed from that observed upon Lamin A/C introduction. Of relevance, short hairpin RNA Lamin A/C depletion in unmethylated neuroblastoma cells enhanced the aforementioned tumour properties. A cytoskeletal structure similar to that observed in methylated cells was induced. Furthermore, atomic force microscopy revealed that Lamin A/C knockdown decreased cellular stiffness in the lamellar region. Finally, the bioinformatic analysis of a set of methylation arrays of neuroblastoma primary tumours showed that a group of patients (around 3%) gives a methylation signal in some of the CpG sites located within the Lamin A/C promoter region analysed by bisulphite sequencing PCR. These findings highlight the importance of Lamin A/C epigenetic inactivation for a subset of neuroblastomas, leading to enhanced tumour properties and cytoskeletal changes. Additionally, these findings may have treatment implications because tumour cells lacking Lamin A/C exhibit more aggressive behaviour.
核纤层蛋白支撑核膜并为染色质提供锚定位点。它们参与DNA合成、转录和复制。此前有报道称，淋巴瘤和白血病中缺乏核纤层蛋白A/C表达是由于CpG岛启动子高甲基化所致。在此，我们提供证据表明，在一部分神经母细胞瘤细胞中，核纤层蛋白A/C通过这种机制被沉默。此外，用去甲基化剂可恢复核纤层蛋白A/C的表达。重要的是，重新引入核纤层蛋白A/C可降低细胞生长动力学，并损害迁移、侵袭和非锚定依赖性细胞生长。还诱导了细胞骨架重构。此外，引入称为早老素的核纤层蛋白Δ50会导致这些神经母细胞瘤细胞衰老。这些细胞更硬，并形成了一种与引入核纤层蛋白A/C时观察到的细胞骨架结构不同的结构。相关的是，在未甲基化的神经母细胞瘤细胞中用短发夹RNA敲低核纤层蛋白A/C会增强上述肿瘤特性。诱导出了一种与在甲基化细胞中观察到的类似的细胞骨架结构。此外，原子力显微镜显示，敲低核纤层蛋白A/C会降低片状区域的细胞硬度。最后，对一组神经母细胞瘤原发性肿瘤的甲基化阵列进行的生物信息学分析表明，一组患者（约3%）在通过亚硫酸氢盐测序PCR分析的核纤层蛋白A/C启动子区域内的一些CpG位点给出了甲基化信号。这些发现突出了核纤层蛋白A/C表观遗传失活对一部分神经母细胞瘤的重要性，导致肿瘤特性增强和细胞骨架变化。此外，这些发现可能具有治疗意义，因为缺乏核纤层蛋白A/C的肿瘤细胞表现出更具侵袭性的行为。
