Lin Shan, Wei Junping, Wunderlich Mark, Chou Fu-Sheng, Mulloy James C
Cancer and Blood Disease Institute, Cincinnati Children's Hospital Research Center, Cincinnati, OH, USA.
Oncotarget. 2016 Aug 30;7(35):55939-55950. doi: 10.18632/oncotarget.11093.
Human CD34+ hematopoietic stem and progenitor cells (HSPC) expressing fusion protein AML1-ETO (AE), generated by the t(8;21)(q22;q22) rearrangement, manifest enhanced self-renewal and dysregulated differentiation without leukemic transformation, representing a pre-leukemia stage. Enabling replicative immortalization via telomerase reactivation is a crucial step in cancer development. However, AE expression alone is not sufficient to maintain high telomerase activity to immortalize human HSPC cells, which may hamper transformation. Here, we investigated the cooperativity of telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, and AE in disease progression. Enforced expression of hTERT immortalized human AE pre-leukemia cells in a telomere-lengthening independent manner, and improved the pre-leukemia stem cell function by enhancing cell proliferation and survival. AE-hTERT cells retained cytokine dependency and multi-lineage differentiation potential similar to parental AE clones. Over the short-term, AE-hTERT cells did not show features of stepwise transformation, with no leukemogenecity evident upon initial injection into immunodeficient mice. Strikingly, after extended culture, we observed full transformation of one AE-hTERT clone, which recapitulated the disease evolution process in patients and emphasizes the importance of acquiring cooperating mutations in t(8;21) AML leukemogenesis. In summary, achieving unlimited proliferative potential via hTERT activation, and thereby allowing for acquisition of additional mutations, is a critical link for transition from pre-leukemia to overt disease in human cells. AE-hTERT cells represent a tractable model to study cooperating genetic lesions important for t(8;21) AML disease progression.
由t(8;21)(q22;q22)重排产生的表达融合蛋白AML1-ETO（AE）的人类CD34+造血干细胞和祖细胞（HSPC）表现出自我更新增强和分化失调，但无白血病转化，代表白血病前期阶段。通过端粒酶重新激活实现复制性永生化是癌症发展的关键步骤。然而，单独的AE表达不足以维持高端粒酶活性以使人类HSPC细胞永生化，这可能会阻碍转化。在此，我们研究了端粒酶催化亚基端粒酶逆转录酶（hTERT）与AE在疾病进展中的协同作用。hTERT的强制表达以不依赖端粒延长的方式使人类AE白血病前期细胞永生化，并通过增强细胞增殖和存活改善白血病前期干细胞功能。AE-hTERT细胞保留了与亲本AE克隆相似的细胞因子依赖性和多谱系分化潜能。在短期内，AE-hTERT细胞未显示逐步转化的特征，初次注射到免疫缺陷小鼠中时未表现出明显的致白血病性。引人注目的是，经过长时间培养后，我们观察到一个AE-hTERT克隆完全转化，这概括了患者的疾病演变过程，并强调了在t(8;21) AML白血病发生过程中获得协同突变的重要性。总之，通过hTERT激活实现无限增殖潜能，从而允许获得额外突变，是人类细胞从白血病前期转变为明显疾病的关键环节。AE-hTERT细胞代表了一个易于处理的模型，用于研究对t(8;21) AML疾病进展重要的协同遗传损伤。
