癌蛋白HBXIP调控Hippo-YAP通路促进乳腺癌增殖的作用及其分子机制研究

YAP transcription coactivator is closely related to the development of cancer, which could be inhibited by the Hippo signaling pathway. Our previous study found that hepatitis B X-interacting protein (HBXIP) was a new coactivator oncoprotein. The overexpression of HBXIP in Drosophila melanogaster is able to rescue the phenotype of no wings resulted by Hippo overexpression. HBXIP is able to promote the proliferation and migration of breast cancer cells through interacting with YAP and regulating Hippo signaling, suggesting that YAP plays an important role in promoting breast cancer cell proliferation by HBXIP. Therefore, it is significant to demonstrate the role and mechanism of HBXIP in promotion of proliferation of breast cancer via the Hippo pathway. Based on our previous study, the subject will focus on the topics as follows: investigate the regulation of Hippo signaling pathway by HBXIP in breast cancer using RNA interference, luciferase reporter gene assay, western blot, immunohistochemistry and other methods at the levels of animal, tissue, cell and molecule; clarify the signaling pathways and molecular mechanisms about the regulation, involving methylation of YAP, by HBXIP through Mst1/2, Lats1/2 and TEADs cascades and co-localization of HBXIP and YAP by using qRT-PCR, ChIP, EMSA and other methods. This research will enrich the mechanisms of breast cancer cell proliferation by HBXIP, providing a new target for the drug discovery of anti-cancer.

YAP转录共激活子与癌症密切相关，并且可被Hippo信号通路所抑制。本课题组前期研究发现，乙肝病毒X蛋白结合蛋白（HBXIP）是一个新的辅激活因子癌基因,在果蝇翅膀过表达HBXIP可营救Hippo过表达无翅膀的表型,并发现HBXIP可通过与YAP相互作用和调控其上游Hippo信号促进乳腺癌细胞的增殖，提示HBXIP是Hippo-YAP信号通路中非常重要的调控因子。本课题拟在大量前期工作基础上，从以下主要方面进行研究：应用RNA干扰、报告基因、免疫印迹和免疫组化等手段，在果蝇模型、动物成瘤、组织、细胞和分子水平进一步阐明HBXIP对YAP及其转录复合物TEADs的调控机制；从基因或蛋白甲基化等角度，阐明HBXIP对YAP上游途径Mst1/2和 Lats1/2等信号的调控机制。本课题研究将揭示HBXIP调节Hippo-YAP信号通路促进乳腺癌细胞增殖的作用及分子机制，为肿瘤的治疗提供新的靶点。

YAP转录共激活子与癌症密切相关，并且可被Hippo信号通路所抑制。乙肝病毒X蛋白结合蛋白（HBXIP）是一个新的辅激活因子癌基因,本研究前期工作显示，HBXIP是Hippo-YAP信号通路中非常重要的调控因子。本课题组主要对HBXIP对YAP及其转录复合物TEADs 的调控机制进行了深入的研究，获得了系列原始创新性结果。主要发现如下：在乳腺癌组织和细胞系中，HBXIP与YAP呈显著的正相关；在过表达HBXIP的情况下干扰YAP，细胞的增殖能力得到了明显的抑制；明确了HBXIP调控YAP的核心启动区；HBXIP通过辅激活转录因子c-Myb,上调YAP的表达，并可抑制YAP的磷酸化水平; HBXIP不与YAP直接结合，但可通过其亮氨酸拉链与TEAD直接结合，并与YAP共同调节TEAD的转录激活功能。本研究首次揭示了HBXIP调控Hippo通路的分子机制，为肿瘤的治疗提供新的靶点。