乳腺癌是女性常见的恶性肿瘤，其发病率在我国持续上升。最新研究发现，环状RNA( circular RNA, circRNA) 是一类特殊的非编码RNA分子，在肿瘤的发生发展中发挥重要调控作用。我们的前期研究发现，环状RNA CCNB1（circ-CCNB1）在乳腺癌中表达明显下降。在乳腺癌细胞中过表达circ-CCNB1，可抑制肿瘤细胞的增殖、侵袭及迁移。同时，过表达circ-CCNB1可下调肿瘤细胞核中周期蛋白依赖性激酶1（Cdk1）以及细胞周期蛋白B1（CyclinB1）的表达。进一步研究发现，circ-CCNB1与Cdk1以及CyclinB1存在结构结合位点。因此我们认为circ-CCNB1可能通过抑制Cdk1-cyclinB1复合物形成及转位入核，阻滞细胞周期进展，抑制乳腺癌的发生发展。本项目将在体内外证实circ-CCNB1的调控作用及分子机制，为乳腺癌的治疗提供理论及实验基础。

Breast cancer is a common female malignant tumor, and the morbidity of breast cancer increase gradually in our country. Circular RNA (circRNA) is one of the special non-coding RNAs, it play an important role in the development of tumor. In our previous study, we have demonstrated that the expression of circ-CCNB1 decreased significantly in breast cancer. Overexpress circ-CCNB1 in breast cancer cells can inhibit proliferation, invasion and migration of tumor cells. The expression of Cyclin-dependent kinases 1 (Cdk1) and CyclinB1 was also inhibited by circ-CCNB1. Furthermore, we also proved that circ-CCNB1 can interact with Cdk1 and CyclinB1. So we hypothesized that circ-CCNB1 can inhibit Cdk1-cyclinB1 complex formation and the nucleus translocation, arrest cell cycle, and inhibit invasion and metastasis in breast cancer. This study can provide fundamental knowledge for breast cancer targeted therapy.