Gao Chen, Xing Xiumei, He Zhini, Chen Shen, Wang Shan, Li Qingye, Guo Ping, Zhang Haiyan, Li Huiyao, Chen Liping, Wang Qing, Zhao Jian, Xiao Yongmei, Chen Wen, Li Daochuan
Department of Toxicology, Guangzhou Key Laboratory of Environmental Pollution and Health Risk Assessment, School of Public Health, Sun Yat-sen University, Guangzhou, China.
Department of Chest Surgery, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, China.
Gene. 2018 Feb 5;642:505-512. doi: 10.1016/j.gene.2017.11.063. Epub 2017 Nov 28.
Cell immortalization is the initial step for cancer development. To identify the differentially expressed genes regulated by DNA methylation over the course of human primary bronchial epithelial cell (HPBECs) immortalization, an immortalized HBE cell line (HBETT) was generated via introduction of an SV40 LT and a catalytic subunit of human telomerase reverse transcriptase (hTERT) into the HPBECs. Microarrays of mRNA and DNA methylation were performed to compare the transcriptomes and DNA methylomes between these two types of cells. The results from the mRNA microarray revealed many genes whose expression changed upon cell immortalization. We identified signatures including global hypomethylation, perturbation of ECM-receptor interaction, focal adhesion, and PI3K-Akt pathways associated with cell immortalization. Moreover, we revealed 155 differentiated methylation regions (DMRs) within the CpG islands (CGIs) of 42 genes and the perturbation of several key pathways that might be involved in HBE cell immortalization. Among these genes, the hypermethylation of the plasma glutamate carboxypeptidase (PGCP) gene appeared specifically in lung cancer tissues. The inhibition of PGCP expression by promoter hypermethylation was observed in both immortal HBETT cells and benzo[a]pyrene (Bap)-transformed HBE cells. In conclusion, these findings provide new insight into the epigenetic modifications that are critical in the transition and maintenance of cell immortalization.
细胞永生化是癌症发展的起始步骤。为了鉴定在人原代支气管上皮细胞（HPBECs）永生化过程中受DNA甲基化调控的差异表达基因，通过将SV40大T抗原（SV40 LT）和人端粒酶逆转录酶催化亚基（hTERT）导入HPBECs，构建了永生化的HBE细胞系（HBETT）。进行了mRNA和DNA甲基化微阵列分析，以比较这两种细胞类型之间的转录组和DNA甲基化组。mRNA微阵列的结果揭示了许多在细胞永生化时表达发生变化的基因。我们鉴定出了包括整体低甲基化、细胞外基质受体相互作用、粘着斑和PI3K-Akt信号通路紊乱等与细胞永生化相关的特征。此外，我们还揭示了42个基因的CpG岛（CGIs）内的155个差异甲基化区域（DMRs），以及可能参与HBE细胞永生化的几个关键信号通路的紊乱。在这些基因中，血浆谷氨酸羧肽酶（PGCP）基因的高甲基化在肺癌组织中特异性出现。在永生化的HBETT细胞和苯并[a]芘（Bap）转化的HBE细胞中均观察到PGCP基因启动子高甲基化导致的表达抑制。总之，这些发现为细胞永生化的转变和维持过程中至关重要的表观遗传修饰提供了新的见解。
