DDX3X作为一种重要的RNA解旋酶和RNA结合蛋白，在乳腺癌的发生发展中起着关键的调控作用。本项目前期的研究发现DDX3X的表达抑制可影响下游miRNA表达谱（尤其是miR-19b和miR-20a）的显著改变，并发现MYLIP可能是miR-19b和miR-20a下游的一个共同靶基因。基于此，本项目提出了“DDX3X通过与Drosha/DGCR8复合体（miRNA微处理器）发生相互作用，加速miR-19b和miR-20a的生物合成过程，上调miR-19b与miR-20a的表达水平，进而抑制两者下游共同靶基因MYLIP的表达，促进乳腺癌的侵袭转移”这一科学假说，期望通过实验进行验证并构建一条新型的“DDX3X---Drosha/DGCR8---miR-19b/miR-20a---MYLIP---肿瘤侵袭转移”调控轴，为阐明其在乳腺癌侵袭转移中的分子机制和生物学效应提供新的实验证据。

DDX3X acts as a key RNA helicase and RNA binding protein to play an essential role in the development of breast cancer. In our previous studies, we have found that the inhibition of DDX3X expression could significantly alter the miRNA expression profile, especially for the miR-19b and miR-20a. Moreover, the database for the prediction of miRNA targets showed that MYLIP might be a potential target gene for both miR-19b and miR-20a. Based on these previous works, we put forward a scientific hypothesis that through interacting with Drosha/DGCR8 complex (miRNA microprocessor), DDX3X could enhance the biogenesis process of miR-19b and miR-20a, and further up-regulate the expression levels of these two miRNAs. Then, the up-regulation of miR-19b and miR-20a could lead to the down-regulation of MYLIP, so as to facilitate the metastasis of breast cancer cells. Overall, this project will establish a novel “DDX3X---Drosha/DGCR8---miR-19b/miR-20a---MYLIP---metastasis” signaling axis, and provide new evidences for the molecular mechanism and biological effect on breast cancer metastasis.