hTERT phosphorylation by PKC is essential for telomerase holoprotein integrity and enzyme activity in head neck cancer cells.
hTERT phosphorylation by PKC is essential for telomerase holoprotein integrity and enzyme activity in head neck cancer cells.
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PKC的HTERT磷酸化对于头颈癌细胞中的端粒酶多蛋白完整性和酶活性至关重要。
DOI：
10.1038/sj.bjc.6603008
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发表时间：
2006-03-27
影响因子：
8.8
通讯作者：
Cheng, AJ
中科院分区：
文献类型：
--
作者：
Chang, JT;Lu, YC;Chen, YJ;Tseng, CP;Chen, YL;Fang, CW;Cheng, AJ
端粒酶活性在正常体细胞组织中被抑制，但在大多数癌细胞中被激活。我们以前已经发现，所有六个端粒酶亚基蛋白，包括hTERT和hsp 90都是完全酶活性所必需的。蛋白激酶C（PKC）可上调端粒酶活性，但其机制尚不清楚。在这项研究中，我们研究了PKC如何调节头颈癌细胞的端粒酶活性。PKC抑制剂双吲哚马来酰亚胺I（BIS）可抑制端粒酶活性，但对端粒酶核心亚基的表达无影响。RNA干扰（RNAi）和体外磷酸化研究表明，PKC亚型α、β、δ、ε、κ α特异性参与端粒酶的调控，磷酸化靶点在hTERT上。用hsp-90抑制剂新生霉素处理使hsp-90和hTERT解离，如免疫沉淀和免疫印迹分析所示，并降低端粒酶活性。用PKC激活剂SC-10治疗恢复了hsp 90和hTERT的结合，并重新激活端粒酶，表明PKC对hTERT的磷酸化对端粒酶全酶的完整性和功能至关重要。对临床正常组织和肿瘤组织的分析表明，PKC α、β、δ、ε、ε在肿瘤组织中表达较高，且与端粒酶活性相关。破坏PKC磷酸化的BIS显着增加顺铂的化疗敏感性。结论：头颈部癌细胞中PKC同工酶α、β、δ、ε、β通过磷酸化hTERT调节端粒酶活性。这种磷酸化是端粒酶全酶组装所必需的，导致端粒酶活化和肿瘤发生。PKC抑制剂对端粒酶活性的调控是一种值得探索的辅助治疗方法。
Telomerase activity is suppressed in normal somatic tissues but is activated in most cancer cells. We have previously found that all six telomerase subunit proteins, including hTERT and hsp90 are needed for full enzyme activity. Telomerase activity has been reported to be upregulated by protein kinase C (PKC), but the mechanism is not clear. In this study, we examined how PKC regulates telomerase activity in head and neck cancer cells. PKC inhibitor, bisindolylmaleimide I (BIS), inhibited telomerase activity but had no effect on the expressions of telomerase core subunits. RNA interference (RNAi) and in vitro phosphorylation studies revealed that PKC isoforms α, β, δ, ε, ζ specifically involved in telomerase regulation, and the phosphorylation target was on hTERT. Treatment with the hsp-90 inhibitor novobiocin dissociated hsp90 and hTERT as revealed by immunoprecipitation and immunoblot analysis and reduced telomerase activity. Treatment with the PKC activator SC-10 restored the association of hsp90 and hTERT and reactivate telomerase, suggesting that hTERT phosphorylation by PKC is essential for telomerase holoenzyme integrity and function. Analysis on clinical normal and tumour tissues reveal that the expressions of PKC α, β, δ, ε, ζ were higher in the tumour tissues, correlated with telomerase activity. Disruption of PKC phosphorylation by BIS significantly increased chemosensitivity to cisplatin. In conclusion, PKC isoenzymes α, β, δ, ε, ζ regulate telomerase activity in head and neck cancer cells by phosphorylating hTERT. This phosphorylation is essential for telomerase holoenzyme assembly, leading to telomerase activation and oncogenesis. Manipulation of telomerase activity by PKC inhibitors is worth exploring as an adjuvant therapeutic approach.
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DOI：
10.1111/j.1349-7006.1999.tb00745.x
发表时间：
1999-03
期刊：
Japanese journal of cancer research : Gann
影响因子：
--
作者：
Cheng AJ;Tang R;Wang JY;Chang JT;Wang TC
通讯作者：
Wang TC
影响因子：
4.8
作者：
Abbas, T;White, D;Bargonetti, J
通讯作者：
Bargonetti, J
影响因子：
4.8
作者：
Li, H;Zhao, LL;Liu, JP
通讯作者：
Liu, JP
影响因子：
56.9
作者：
FENG, JL;FUNK, WD;VILLEPONTEAU, B
通讯作者：
VILLEPONTEAU, B
影响因子：
56.9
作者：
Lingner, J;Hughes, TR;Cech, TR
通讯作者：
Cech, TR