CD133功能及其介导的自噬在肝肿瘤耐药中的作用

Intrinsic or acquired chemoresistance is a major cause of treatment failure of most hepatocarcinomas. Understanding mechanisms of chemoresistance is vital for personalized treatment and survival of patients with cancer. CD133, also called prominin-1, widely used to detect tumorigenesis and chemoresistance of a variety of cancer stem cells. However, most of studies focus on CD133 positive cells rather than CD133 itself in tumor growth as well as the relationship between CD133 and chemoresistance. We find that CD133 positive cells have the ability of chemoresistance to cisplatin. Overexpression of CD133 prolongs survival period of cells in nutrition dprivation. Interestingly, CD133 appears involving autophagy by itself. Forced expression of CD133 promotes autophagy, while inhibition of CD133 by siRNA suppresses autophagy and level of LC3, one of autophagic associated proteins. Autophagic activity is believed to be responsible for chemoresistance and drug sensitivity. We are inspired by the idea that CD133-mediated autophagy may be important in chemoresistance governed by cancer stem cells. Therefore, the aim of this project is to deeply reveal mechanism of CD133-mediated autophagy and its membrane dynamic change during chemotherapy, and how this group of cells affect their neighborhood cells. The results of this projet will provide new evidence for reducing chemoresistance of hepatocarcinoma.

内在和获得性的耐药是最终导致大多数肝癌治疗失败的原因。了解耐药产生的机制对个性化药物治疗和延长患者的生命都是至关重要的。CD133被广泛用于检测各种肿瘤干细胞的成瘤性和耐药性,但大多数研究局限于CD133阳性细胞而忽视了CD133本身的作用以及CD13与耐药形成的关系。我们发现CD133阳性细胞具有对化疗药顺铂的拮抗性，高表达CD133可延长细胞在营养缺乏状态下的存活时间，有趣的是CD133本身似乎参与细胞自噬反应。过表达CD133促进自噬，抑制CD133则明显降低自噬和自噬相关蛋白LC3的水平。自噬的活性与肿瘤耐药和药物敏感性有一定关系，肿瘤干细胞是否通过CD133介导的自噬而产生耐药尚不清楚。因此，本课题的研究目的是深入揭示CD133功能及其介导的自噬机制和膜动态变化与耐药形成的关系，从细胞群体层面研究CD133阳性细胞的生存与相邻相邻细胞的关系，为降低肝癌耐药提供新的依据。

CD133，又叫prominin-1，广泛作为检测各种肿瘤干细胞的成瘤性和耐药性的标志物已经在广泛应用。前期研究工作发现CD133在肝肿瘤组织表达相对癌旁组织升高并且与不良预后有关。CD133 被认为是肿瘤干细胞的重要标志物，而肿瘤干细胞与肿瘤的复发和耐药有关。然而，对CD133蛋白本身在肿瘤发生发展中的作用还不清楚。基于对这一问题的思考和设想，本课题获得资助并聚焦于细胞膜蛋白CD133本身的作用机制以及CD13在肝癌耐药作用中的机制进行了研究。经过多方面研究，我们完成了以下内容并获得有价值的结果：1）CD133参与细胞生存特别在低糖状态下，促进细胞对葡萄糖的摄取；2）首次发现CD133参与自噬反应，高表达CD133 促进自噬，低表达则降低自噬活性，并证实CD133介导的自噬可能是肿瘤干细胞生存、复发、耐药的原因之一；3) 抑制CD133受体和降低自噬活性能增加肝癌细胞对Doxorubicin和Cisplatin的敏感性。提示自噬的检测和变化可作为肿瘤耐药检测的重要指标；4）CD133在胞膜-自噬体-溶酶体和线粒体随细胞状态发生动态变化并且CD133的表达受细胞微环境的影响。实验结果表明CD133是一个功能性蛋白，其表达水平反映肿瘤的生长状态，通过影响肿瘤细胞的自噬发应，可改善肿瘤细胞对化疗药的敏感性。