Riquelme Erick, Suraokar Milind B, Rodriguez Jaime, Mino Barbara, Lin Heather Y, Rice David C, Tsao Anne, Wistuba Ignacio I
Department of Translational Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
Department of Biostatistics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
J Thorac Oncol. 2014 Jul;9(7):998-1007. doi: 10.1097/JTO.0000000000000202.
Malignant pleural mesothelioma (MPM) is a deadly disease with poor prognosis and few treatment options. We characterized and elucidated the roles of C-MYC and PVT1 involved in the pathogenesis of MPM.
We used small interfering RNA (siRNA)-mediated knockdown in MPM cell lines to determine the effect of C-MYC and PVT1 abrogation on MPM cells undergoing apoptosis, proliferation, and cisplatin sensitivity. We also characterized the expression of microRNAs spanning the PVT1 region in MPM cell lines. Copy number analysis was measured by quantitative polymerase chain reaction and fluorescence in situ hybridization.
Copy number analysis revealed copy number gains (CNGs) in chromosomal region 8q24 in six of 12 MPM cell lines. MicroRNA analysis showed high miR-1204 expression in MSTO-211H cell lines with four copies or more of PVT1. Knockdown by siRNA showed increased PARP-C levels in MSTO-211H transfected with siPVT1 but not in cells transfected with siC-MYC. C-MYC and PVT1 knockdown reduced cell proliferation and increased sensitivity to cisplatin. Analysis of the expression of apoptosis-related genes in the MSTO-211H cell line suggested that C-MYC maintains a balance between proapoptotic and antiapoptotic gene expression, whereas PVT1 and, to a lesser extent, miR-1204 up-regulate proapoptotic genes and down-regulate antiapoptotic genes. Fluorescence in situ hybridization analysis of MPM tumor specimens showed a high frequency of both CNGs (11 of 75) and trisomy (three copies; 11 of 75) for the C-MYC locus.
Our results suggest that C-MYC and PVT1 CNG promotes a malignant phenotype of MPM, with C-MYC CNG stimulating cell proliferation and PVT1 both stimulating proliferation and inhibiting apoptosis.
恶性胸膜间皮瘤（MPM）是一种预后不良且治疗选择有限的致命疾病。我们对参与MPM发病机制的C-MYC和PVT1的作用进行了表征和阐释。
我们在MPM细胞系中使用小干扰RNA（siRNA）介导的敲低技术，以确定C-MYC和PVT1缺失对经历凋亡、增殖和顺铂敏感性的MPM细胞的影响。我们还对MPM细胞系中跨越PVT1区域的微小RNA的表达进行了表征。通过定量聚合酶链反应和荧光原位杂交测量拷贝数分析。
拷贝数分析显示，12个MPM细胞系中有6个在染色体区域8q24存在拷贝数增加（CNGs）。微小RNA分析显示，在具有四个或更多PVT1拷贝的MSTO-211H细胞系中miR-1204表达较高。siRNA敲低显示，用siPVT1转染的MSTO-211H细胞中PARP-C水平升高，但用siC-MYC转染的细胞中未升高。C-MYC和PVT1敲低减少了细胞增殖并增加了对顺铂的敏感性。对MSTO-211H细胞系中凋亡相关基因表达的分析表明，C-MYC维持促凋亡和抗凋亡基因表达之间的平衡，而PVT1以及在较小程度上miR-1204上调促凋亡基因并下调抗凋亡基因。MPM肿瘤标本的荧光原位杂交分析显示，C-MYC基因座的CNGs（75个中有11个）和三体性（三个拷贝；75个中有11个）频率都很高。
我们的结果表明，C-MYC和PVT1的CNG促进了MPM的恶性表型，C-MYC的CNG刺激细胞增殖，而PVT1既刺激增殖又抑制凋亡。
