来自华盛顿州立大学的研究人员发现了一种方法能使癌细胞正常老化和死亡，这有望开辟新颖的减缓，甚至停止肿瘤生长的方式。
"如果可能的话，我们能够使癌细胞像正常细胞那样死亡，"华盛顿州立大学分子生物学学院的副教授Weihang Chai表示，"大体上可使癌细胞在"永生"中受到威胁。"
我们知道，正常细胞每次在复制的时候会丢失一些他们原先的DNA，即DNA分子链的保护端-端粒的部分丢失。最终的结果是，端粒变得太短，发出使细胞停止复制和生长的信号。
癌细胞具有保持DNA链缩减的机制，这使得它们具有几乎永恒的生命。这是因为端粒酶扩展了癌细胞的DNA，而其他的蛋白促使了另一条链的延伸。
Chai和她的同事们，在最新一期的EMBO Journal杂志上发布了这项研究，他们发现一个调控蛋白能够控制第二股链的延伸，另外还发现了一种对该链合成来说是必需的蛋白。
Chai表示，如果第二股DNA链不能被延长，那么癌细胞就会像正常细胞那样运作，像正常细胞那样死亡。研究团队目前正关注于抑制这种调控蛋白发挥功能的策略开发。(生物谷Bioon.com)
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生物谷推荐原文出处：
The EMBO Journal doi:10.1038/emboj.2010.156
Molecular steps of G-overhang generation at human telomeres and its function in chromosome end protection
Xueyu Dai1,2,4, Chenhui Huang1,2,4, Amruta Bhusari3,4,5, Shilpa Sampathi1,2, Kathryn Schubert1 and Weihang Chai1,2
1 WWAMI Medical Education Program, Washington State University, Spokane, WA, USA
2 School of Molecular Biosciences, Washington State University, Pullman, WA, USA
3 Department of Biology, Texas Woman's University, Denton, TX, USA
Telomeric G-overhangs are required for the formation of the protective telomere structure and telomerase action. However, the mechanism controlling G-overhang generation at human telomeres is poorly understood. Here, we show that G-overhangs can undergo cell cycle-regulated changes independent of telomerase activity. G-overhangs at lagging telomeres are lengthened in S phase and then shortened in late S/G2 because of C-strand fill-in, whereas the sizes of G-overhangs at leading telomeres remain stable throughout S phase and are lengthened in G2/M. The final nucleotides at measurable C-strands are precisely defined throughout the cell cycle, indicating that C-strand resection is strictly regulated. We demonstrate that C-strand fill-in is mediated by DNA polymerase α (polα) and controlled by cyclin-dependent kinase 1 (CDK1). Inhibition of CDK1 leads to accumulation of lengthened G-overhangs and induces telomeric DNA damage response. Furthermore, depletion of hStn1 results in elongation of G-overhangs and an increase in telomeric DNA damage. Our results suggest that G-overhang generation at human telomeres is regulated by multiple tightly controlled processes and C-strand fill-in is under the control of polα and CDK1.
