端粒、端粒酶及hTERT／hTERC基因的研究进展

端粒是真核细胞染色体的末端DNA序列，在维持染色体稳定性中起重要作用。染色体的不完全复制使得端粒随着细胞的分裂而逐渐缩短，快速分裂细胞通过端粒酶合成端粒，以弥补端粒的消耗。端粒酶相关基因突变可导致端粒酶活性的降低和端粒缩短，过短的端粒不再保护基因组稳定性，将引起细胞的老化、凋亡或恶变。端粒酶基因的扩增出现在一些肿瘤细胞中，是癌细胞增殖的重要原因，其扩增的机制及其对端粒酶活性的调节作用尚不完全清楚。近期研究表明，端粒酶基因扩增是基因组不稳定的结果，扩增的hTERT／hTERC基因对端粒酶激活和癌变进展有促进作用。

The research progress on Telomere, Telomerase and hTERT/hTERC genes

Telomere, the DNA sequences at the end of chromosome of eukaryotic cells, is important in maintaining genomic stability. Telomeres gradually decrease in length during each cell division, owing to incomplete replication of terminal DNA. Telomeric repeats are synthesized by telomerase to make up for the telomere attrition in growing rapidly cells. Telomerase gene mutations may lead to the reduction of telomerase activity and telomere length. When telomere length becomes critically short, it can no longer protect genomic stability, triggering senescence, aging or carcinogenesis. Amplification of telomerase gene is found in several tumor cells, which plays an important role in cancer cells proliferation. The mechanism of telomerase gene amplification and its regulation on telomerase activity is still currently unknown. Recent studies show that telomerase gene amplification is the consequence of genomic instability, and the gain of hTERT / hTERC play a primitive role in telomerase activation and cell immortalization.