Aurora-A是一种参与有丝分裂的丝氨酸/苏氨酸激酶,其过表达与肿瘤形成有关。Aurora-A激酶活性可以通过磷酸化、去磷酸化以及依赖蛋白酶体的降解等方式进行调节。TPX2(target protein for Xenopus kinesin-like protein 2)、1-2(Inhibitor 2)、Ajuba通过磷酸化Aurora-A将其活化,PP1(type-1 proteinphosphatase)等通过去磷酸化Aurora-A而抑制其活性,而且APC／C-Cdh1依赖的蛋白酶体等可以将其降解。了解和认识Aumra-A激酶活性调节的分子机制将有助于理解它在有丝分裂及肿瘤形成中的作用。
Attrora-A kinase, a serine/threonine protein kinase, is a potential oncogene. Amplification and overexpression of Aurora-A have been found in several types of human tumors, including esophageal squamous cell carcinoma （ESCC）. It has been demonstrated that cells overexpressing Attrora-A are more resistant to cisplatin-induced apoptosis. However, the molecular mechanisms mediating these effects remain largely unknown. In this report, we showed that overexpression of Attrora-A through stable transfection of pEGFP-Aurora-A in human ESCC KYSE150 cells significantly promoted cell proliferation and inhibited cisplatin- or UV irradiation-induced apoptosis. Cleavages of caspase-3 and poly （ADPribose） polymerase （PARP） in Attrora-A overexpressing cells were substantially reduced after cisplatin or UV treatment. Furthermore, we found that silencing of endogenous Aurora-A kinase with siRNA substantially enhanced sensitivity to cisplatin- or UV-induced apoptosis in human ESCC EC9706 cells. In parallel, overexpression of Aurora-A potently upregulated the expression of Bcl-2. Moreover, the knockdown of Bcl-2 by siRNA abrogated the Aurora-A＇s effect on inhibiting apoptosis. Taken together, these data provide evidence that Aurora-A overexpression promoting cell proliferation and inhibiting apoptosis, suggesting a novel mechanism that is closely related to malignant phenotype and anti-cancer drugs resistance of ESCC cells.
Xiao Xia WangRong LiuShun Qian JinFei Yue FanQi Min Zhan
