miR-221对膀胱癌细胞的自噬调控作用与分子机制研究

MicroRNA and autophagy both are the current research focus in life science. The potential prospect of regulating effect and mechanism of MicroRNA on autophagy attracts more and more researchers’ attention. Our recent studies found high expression of miR-211 in several urinary bladder cancer cells, and low expression of miR-211 silenced by siRNA will decrease the proliferative and invasive activity of cancer cells and induce cell apoptosis, which is related with the fact that miR-211 functions on its target PUMA gene. However its intrinsic mechanism and potential application are still largely unknown. Recently, some researchers found over expression of miR-221 in heart will lead myocardial hypertrophy and subsequent heart failure via inhibiting the autophagy in cardiomyocytes. Moreover, mutual regulation exists between PUMA and autophagy. Based on our and others’ study results we postulate that the negative effect of miR-211 on inhibiting bladder cancer cell viability may be related to its function on regulating cell autophagy. Furthermore, people are still not clear whether miR-221 plays the regulation role on bladder cancer cell autophagy via targeting PUMA or other down-stream genes, and what key autophagy-associated genes and related pathways are involved in the process. More explorations are deserved on these myths for its importance. In our project, in vivo and in vitro experiments using such techniques as PCR Array, RNA interference and co-transfection are designed to explore the regulatory effect of miR-221 on autophagy and its mechanism influencing the carcinogenesis and development of bladder cancer. And further destination is to find the new biomarkers in the network which can be used for the diagnosis and treatment of bladder cancer. We hope the research will expand the understanding of central role of miRNA-autophagy in the regulatory network on carcinogenesis and tumor invasion and metastasis.

微RNA与自噬是生命学领域的研究热点，微RNA对自噬的调控效应与机制近期深受关注。我们前期筛查发现miR-221在多株膀胱癌细胞高表达，沉默后癌细胞的增殖活性与侵袭性明显受抑且出现凋亡，进一步发现miR-221是通过靶向PUMA而发挥作用，更深层的机制不明。近期其它研究证实miR-221会抑制心肌细胞自噬而造成心肌肥厚与心衰；PUMA与自噬有相互调控作用。据此我们推测miR-221影响膀胱癌细胞活性可能与自噬有关。miR-221是否通过靶向PUMA等基因来调控自噬，以及miR-221调控膀胱癌自噬相关基因及信号通路的靶点与机制目前均不清楚，有待深入探讨。本课题拟通过体内外实验，采用基因功能分类芯片、RNA干扰和共转染等技术研究miR-221调节自噬对膀胱癌发生发展的作用与机制，籍此寻找有望用于临床诊治的新靶点。本研究将有助于我们深入了解miRNA-自噬在肿瘤发生发展调控网络中的核心作用。

MicroRNA（miRNA）与肿瘤的发展和转移密切相关。据报道，MiR-221是多种癌症的致癌基因，包括膀胱癌。自噬的失调与多种恶性肿瘤有关。对于膀胱癌中miR-221是否调节自噬以及如何调节自噬目前知之甚少，且在膀胱癌中miR-221受哪种转录因子调节亦是未知。本项目深入探讨了miR-221在膀胱癌自噬和肿瘤发生中的潜在功能和机制。我们发现，下调miR-221可以升高TP53INP1（肿瘤蛋白p53诱导性核蛋白1）从而诱导自噬，并且下调miR-221还可通过抑制ERK的激活来降低膀胱癌细胞的迁移和侵袭能力。此外，miR-221的表达在膀胱癌中主要由HMGA1（高迁移率组AT-hook1）调控。而且高表达的miR-221和HMGA1均与膀胱癌患者预后不良相关。综上，我们的研究表明下调HMGA1的表达可以通过miR-221 / TP53INP1 / p-ERK轴诱导毒性自噬从而抑制了膀胱癌的增殖，迁移和侵袭性。总的来说，我们的研究结果表明miR-221和HMGA1的下调介导了膀胱癌自噬，这两者或将成为膀胱癌治疗的有效靶标。