抑癌siRNA和mRNA共传递用于前列腺癌协同基因治疗的研究

Numerous researches have shown that androgen receptor (AR) mutation or over-expression and loss of tumor suppressor PTEN are associated with the development and progression of prostate cancer (PCa). Therefore, a new therapeutic strategy may be developed for PCa synergistic gene therapy by introduction of AR siRNA and PTEN mRNA to PCa cells to simultaneously up-regulate PTEN expression and down-regulate AR expression. The key scientific issue is how to efficiently co-deliver siRNA and mRNA to cancer cells. We previously developed a new tumor microenvironment (TME) pH-responsive nanocarrier and demonstrated that this nanocarrier can efficiently deliver therapeutic siRNA to PCa cells, leading to cell apoptosis and significant inhibition of PCa tumor growth. In our preliminary study, we further employed this TME pH-responsive nanocarrier to co-deliver AR siRNA and PTEN mRNA. The obtained data indicates that the co-delivery ofthese two RNAs to PCa cells can down-regulate AR expression and up-regulate PTEN expression, showing the ability to simultaneously inhibit the activity of AR and PI3K-AKT pathways. Based on these encouraging experimental results, in this proposal, we will further prepare a series of TME pH-responsive nanocarriers for the co-delivery of AR siRNA and PTEN mRNA. After systemically screening to obtain the optimal nanocarrier with the lowest toxicity but highest delivery efficiency, we will evaluate its efficacy for PCa synergistic gene therapy by using xenograft and metastatic PCa tumor models. We expect that the research proposed here can provide scientific evidence and fundamental mechanism for the exploring new therapeutic strategy for PCa treatment.

大量研究表明雄激素受体AR过表达或突变和抑癌基因PTEN缺失促进前列腺癌的发生发展。使用AR siRNA和PTEN mRNA同时下调AR基因和上调PTEN基因表达，有望成为一种新策略用于前列腺癌的协同基因治疗。其中关键的科学问题是如何将siRNA和mRNA高效共传递至前列腺癌细胞中。前期研究表明，肿瘤弱酸微环境响应的纳米载体可高效传递siRNA至前列腺癌细胞中，引起细胞凋亡并显著抑制肿瘤的生长。预实验证实，上述纳米载体可共传递AR siRNA和PTEN mRNA至前列腺癌细胞中，引起AR表达下调和PTEN表达上调，协同抑制AR和PI3K-AKT信号通路活性。基于以上研究基础，本项目将进一步制备多个肿瘤弱酸微环境响应纳米载体用于上述两种RNA共传递，筛选出低毒高效的纳米载体，在皮下肿瘤和转移瘤模型上考察其协调基因治疗前列腺癌的功效，为开发前列腺癌新疗法提供科学依据和理论基础。

前列腺癌是常见的男性恶性肿瘤之一，已成为危害男性健康的主要问题。大量研究表明雄激素受体AR过表达或突变和抑癌基因PTEN缺失促进前列腺癌的发生发展。使用AR siRNA和PTEN mRNA同时下调AR基因和上调PTEN基因表达，有望成为一种新策略用于前列腺癌的协同基因治疗。但是AR siRNA和PTEN mRNA均属于生物大分子，易被核酸酶降解，体内稳定性差。因此如何设计开发出高效的体内递送载体是AR siRNA和PTEN mRNA临床转化应用的关键所在。在本项目中，我们利用肿瘤组织弱酸微环境的特点，设计开发出肿瘤弱酸微环境响应型高分子纳米载体。通过改变高分子的分子量及投料比成功调控和优化纳米载体的性能（包括尺寸大小、表面电荷、血液循环时间及肿瘤富集能力等），成功筛选出尺寸较小（< 100 nm）、血液循环时间长及肿瘤富集能力强的纳米载体。体内外实验结果表明，包载有AR siRNA 和PTEN mRNA的肿瘤弱酸微环境响应型纳米载体具有较长的血液循环时间和较强的肿瘤组织富集能力，可以显著下调前列腺癌细胞中AR基因表达和上调PTEN基因表达，能够高效抑制PI3K-AKT信号通路活性。相对于单一下调AR基因表达或上调PTEN基因表达，AR siRNA和PTEN mRNA共传递对前列腺癌细胞增殖的抑制作用更强。在前列腺癌小鼠肿瘤模型上，包载有AR siRNA 和PTEN mRNA的肿瘤弱酸微环境响应型纳米载体可以显著下调肿瘤组织中AR基因表达和上调PTEN基因的表达，协同抑制前列腺肿瘤的生长。本项目的研究成果为开发前列腺癌新疗法提供科学依据和理论基础。