Lab of Molecular Genetics of Aging & Tumor, Faculty of Medicine, Kunming University of Science & Technology, 727 South Jing Ming Road, Chenggong County, Kunming, Yunnan Province, China, 650500.
College of Biological Engineering, Qilu University of Technology (Shandong Academy of Sciences), 3501 University Road, Changqing County, Jinan, Shandong Province, China, 250353.
Int J Biol Sci. 2018 Jan 14;14(2):165-177. doi: 10.7150/ijbs.23477. eCollection 2018.
Werner syndrome (WS) is a rare autosomal recessive progeria disease with genetic instability/cancer predisposition, thus a good model in understanding aging related carcinogenesis. Telomere dysfunction induced cellular senescence is essential in the manifestation of the WS phenotype. Our previous data has shown that p21 (encoded by gene) could induce cellular senescence and suppress cellular growth of ALT (alternative lengthening of telomere) tumors derived from WS, suggested that p21 might play a key role in maintaining senescence of WS cells. To confirm the role of p21 in suppressing telomere dysfunction induced tumorigenesis, we overexpressed dominant negative protein TRF2 in mouse embryonic fibroblasts (MEFs). To further stress the cell, we crossed mice with mice to obtained MEFs, and overexpressed TRF2 in these MEFs to induce telomere dysfunction similar to that in WS cells. Our data showed that, in the context of TRF2, loss of p21 function rescued cellular senescence, and induced p53 mutation, but did not induce tumorigenesis. However, in the set of TRF2, loss of p21 function induced p53 mutation and tumorigenesis. To further verify the role of p21 in suppressing telomere dysfunction related tumorigenesis, we knocked down p21 in non-tumorigenic immortalized cells derived from WS MEFs (mTerc ), and found that loss of p21 could induce ALT tumorigenesis, which displayed typical smear pattern of telomere length and arc-shaped telomeric DNA. In another hand, recovering telomerase activity in these MEFs could also induce tumorigenesis without affecting p21 expression level. Together our data suggested that p21 controlled cell cycle regulation played an essential role in suppressing telomere dysfunction-related tumorigenesis. These data also suggested that the genetic context is essential in determining the role of p21 in cancer prevention. Therefore, targeting p21 in the treatment of human degenerative diseases would require a personalized genetic background screen.
沃纳综合征（WS）是一种罕见的常染色体隐性遗传早衰疾病，具有遗传不稳定性/癌症易感性，因此是理解与衰老相关的致癌作用的良好模型。端粒功能障碍诱导的细胞衰老对于表现出 WS 表型至关重要。我们之前的数据表明，p21（由 基因编码）可以诱导细胞衰老并抑制源自 WS 的 ALT（端粒延长的替代途径）肿瘤的细胞生长，这表明 p21可能在维持 WS 细胞衰老中发挥关键作用。为了确认 p21在抑制端粒功能障碍诱导的肿瘤发生中的作用，我们在 小鼠胚胎成纤维细胞（MEFs）中转染显性负性蛋白 TRF2。为了进一步强调细胞，我们将 与 杂交以获得 MEFs，并在这些 MEFs 中转染 TRF2 以诱导类似于 WS 细胞中的端粒功能障碍。我们的数据表明，在 TRF2 的背景下，p21 功能丧失可挽救细胞衰老，并诱导 p53 突变，但不会诱导肿瘤发生。然而，在 TRF2 的情况下，p21 功能丧失会诱导 p53 突变和肿瘤发生。为了进一步验证 p21 在抑制端粒功能障碍相关肿瘤发生中的作用，我们在源自 WS MEFs（mTerc ）的非致瘤性永生化细胞中敲低了 p21，并发现 p21 的缺失可诱导 ALT 肿瘤发生，其显示出典型的端粒长度拖尾模式和弧形端粒 DNA。另一方面，在这些 MEFs 中恢复端粒酶活性也可诱导肿瘤发生，而不影响 p21 表达水平。总之，我们的数据表明，p21 控制细胞周期调节在抑制端粒功能障碍相关肿瘤发生中起着至关重要的作用。这些数据还表明，遗传背景对于确定 p21 在癌症预防中的作用至关重要。因此，针对人类退行性疾病中的 p21 进行靶向治疗需要进行个性化的遗传背景筛查。
