新型转录阻遏因子ILKAP调控骨肉瘤恶性生物学行为的机制研究

Osteosarcoma is the most common primary malignant bone tumor, with high malignance, early metastasis and poor prognosis. There is no definite molecular target point for the cure of osteosarcoma. We found wide rate of dead-activated mutation of a tumor associated phosphatse ILKAP was exist in human osteosarcoma, and ILKAP knockout mice develop osteosarcoma automatically from 16 to 20 weeks. We also found that ILKAP can induce tumor cell apoptosis and it only depends on the activity of phosphatse ILKAP partially. We have overexpressed ILKAP and observed that the expression of some osteosarcoma specific growth factor declined to different degrees. In the meanwhile, the protein structure of ILKAP was found to contain a typical DNA binding region and could regulate gene expression transcriptionally. In these regards, we supposed ILKAP may serve as a new transcriptional repressor in regulating osteosarcoma generation and proliferation. Therefore, we prepare to explore the specific role of ILKAP as a transcriptional repressor in not only molecular and cellular levels but also animal models, and aim to clarify that this mechanism mediates the generation and malignant biological behavior of osteosarcoma. In this study we can provide the new theory of the molecular mechanism in the generation and malignant behavior of human osteosarcoma, and further provide new direction and medicine targets for the cure of osteosarcoma.

骨肉瘤是一种常见的原发恶性骨肿瘤，具有恶性度高、易转移、预后差的特点，尚缺乏明确的分子机制研究及治疗靶点。本项目组发现，一种肿瘤相关蛋白磷酸酶ILKAP在骨肉瘤中存在异常表达及广泛的失活突变，骨骼系统特异敲除ILKAP的转基因鼠在16-20周可以自发地产生骨肉瘤样病变。我们发现ILKAP可以诱导骨肉瘤细胞凋亡，而这种作用并不完全依赖于ILKAP的磷酸酶活性。利用芯片技术我们发现过表达ILKAP后，一些骨肉瘤相关的基因有不同程度的表达下调，通过晶体结构解析及凝胶阻滞实验，我们发现ILKAP蛋白结构含有典型的DNA结合基序，并可以从转录水平调控基因表达。基于这些前期结果我们初步认为ILKAP可能作为一种新的转录阻遏因子，在骨肉瘤发生及增殖中起到关键作用。本项目拟从分子，细胞及动物水平确定ILKAP作为转录阻遏因子调控骨肉瘤恶性生物学行为的过程与机制，为骨肉瘤的治疗提供新的理论基础及药物靶点。

骨肉瘤又称成骨肉瘤，具有恶性程度高、生长迅速、侵袭力强、转移早等肿瘤学特征，其恶性生物学行为演变过程的分子机制研究已经成为国内外骨肉瘤基础研究的焦点。然而，目前对这一分子机制的了解还非常有限，基于骨肉瘤分子特征开发新的治疗手段及药物靶点仍无法实现，这已成为骨肉瘤基础研究与临床治疗的瓶颈。.我们通过高通量测序技术发现ILKAP可能作为一种新的转录阻遏因子，在骨肉瘤发生及增殖中起到关键作用。骨肉瘤中ILKAP表达的下调或突变缺失，导致ILKAP丧失了对骨肉瘤关键癌基因如Ezrin、MMP-9、HSP90等启动子区域的阻遏作用，从转录水平诱发了相关癌基因的异常表达，这些调控功能可能在骨肉瘤发生、增殖以及骨重构过程中起关键作用。本项目组从细胞和分子水平确定ILKAP以转录阻遏因子的角度介导骨肉瘤发生、增殖以及骨重构的过程与机制，为骨肉瘤的治疗提供新的理论基础及药物靶点。.