Evidence for the inactivation of multiple replicative lifespan genes in immortal human squamous cell carcinoma keratinocytes
Evidence for the inactivation of multiple replicative lifespan genes in immortal human squamous cell carcinoma keratinocytes
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DOI：
10.1038/sj.onc.1201028
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发表时间：
1997-04-24
期刊：
影响因子：
8
通讯作者：
Parkinson, EK
中科院分区：
文献类型：
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作者：
Loughran, O;Clark, LJ;Parkinson, EK
人类角质形成细胞永生是遗传隐性的有限复制寿命的正常表型，似乎需要p53和细胞周期蛋白D-Cdk抑制剂p16的功能障碍。为了检测人类肿瘤永生细胞中其他候选复制寿命基因的失活，我们开发了一系列来自头颈部肿瘤病变的致死性和永生性角质形成细胞培养物，这些细胞适合通过杂合性丢失（洛）技术进行分子遗传学分析。结果表明，角质形成细胞永生化在头颈部鳞状细胞癌（SCC-HN）的发展涉及至少两个进一步的途径衰老和四个在所有的失活。染色体1、4和7分别携带代表永生互补组C、B和D的基因，永生角质形成细胞在D4 S1554和D4 S171之间的4 q32-q34（B组）或7 q31（D组）显示LOH，但从未在1 q25（C组）显示LOH。这些结果初步表明，负责永生互补组的基因编码的蛋白质在同一途径衰老。此外，所有永生化角质形成细胞系都具有高水平的端粒酶活性，并且端粒酶活性的抑制因子已被定位于染色体3 p的短臂。8个细胞系中有5个在3p21.2-p21.3出现洛缺失，该区域可能携带能够抑制SCC-HN端粒酶的基因。然而，我们的研究结果也提出了端粒酶再激活的替代机制。在7个衰老肿瘤性角质形成细胞培养物中未观察到上述遗传改变。其他含有与复制寿命有关的抗增殖基因的位点显示很少或没有改变，并且所观察到的任何改变都是上述改变之外的。
Human keratinocyte immortality is genetically recessive to the normal phenotype of limited replicative lifespan and appears to require the dysfunction of p53 and the cyclin D-Cdk inhibitor p16. In order to test for the inactivation of other candidate replicative lifespan genes in the immortal cells of human tumors, we developed a series of mortal and immortal keratinocyte cultures derived from neoplastic lesions of the head and neck which were amenable to molecular genetic analysis by the loss of heterozygosity (LOH) technique. The results indicate that keratinocyte immortalization in head and neck squamous cell carcinoma (SCC-HN) development involves the inactivation of at least two further pathways to senescence and four in all. Chromosomes 1, 4 and 7 carry genes representing immortality complementation groups C, B and D respectively and immortal keratinocytes showed LOH at either 4q32-q34 between D4S1554 and D4S171 (group B) or 7q31 (group D) but never 1q25 (group C). These results tentatively suggest that the genes responsible for the immortality complementation groups encode proteins on the same pathway to senescence. In addition, all of the immortal keratinocyte lines possessed high levels of telomerase activity and a suppressor of telomerase activity has been mapped to the short arm of chromosome 3p. Five out of eight lines showed LOH at 3p21.2-p21.3, a region which may carry a gene capable of suppressing SCC-HN telomerase. However, alternative mechanisms of telomerase reactivation were also suggested by our results. None of the above genetic alterations were seen in seven senescent neoplastic keratinocyte cultures, Other loci harbouring antiproliferative genes implicated in replicative lifespan showed few or no alterations and any alterations seen were additional to those described above.