Shi Hui, Li Yinghui, Feng Guoxing, Li Leilei, Fang Runping, Wang Zhen, Qu Jie, Ding Peijian, Zhang Xiaodong, Ye Lihong
State Key Laboratory of Medicinal Chemical Biology, Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin 300071, PR China.
State Key Laboratory of Medicinal Chemical Biology, Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071, PR China.
Biochem Biophys Res Commun. 2016 Feb 26;471(1):89-94. doi: 10.1016/j.bbrc.2016.01.174. Epub 2016 Jan 29.
We have reported that the oncoprotein hepatitis B X-interacting protein (HBXIP) is able to promote migration of breast cancer cells. Fibroblast growth factor 4 (FGF4) is a multipotent growth factor and is highly expressed in various human cancers. However, the regulatory mechanism of FGF4 in breast cancer remains poorly understood. In the present study, we report that HBXIP is able to up-regulate FGF4 to enhance the migration of breast cancer cells. Immunohistochemistry staining showed that HBXIP and FGF4 were highly expressed in clinical metastatic lymph nodes of breast tumor. The expression levels of HBXIP were positively related to those of FGF4 in clinical breast cancer tissues. Then, we validated that HBXIP up-regulated the expression of FGF4 at the levels of promoter, mRNA and protein by luciferase reporter gene assays, reverse transcription-polymerase chain reaction and Western blot analysis. Moreover, we found that HBXIP was able to activate FGF4 promoter through transcriptional factor Sp1 by luciferase reporter gene assays. Chromatin immunoprecipitation assays confirmed that HBXIP coactivated Sp1 to stimulate FGF4 promoter. In function, we showed that HBXIP promoted breast cancer cell migration through FGF4 by wound healing and transwell cell migration assays. Thus, we conclude that the oncoprotein HBXIP up-regulates FGF4 through activating transcriptional factor Sp1 to promote the migration of breast cancer cells. Therapeutically, HBXIP may serve as a novel target in breast cancer.
我们曾报道过癌蛋白乙型肝炎X相互作用蛋白（HBXIP）能够促进乳腺癌细胞的迁移。成纤维细胞生长因子4（FGF4）是一种多能生长因子，在多种人类癌症中高表达。然而，FGF4在乳腺癌中的调控机制仍知之甚少。在本研究中，我们报道HBXIP能够上调FGF4以增强乳腺癌细胞的迁移。免疫组织化学染色显示，HBXIP和FGF4在乳腺肿瘤临床转移淋巴结中高表达。在临床乳腺癌组织中，HBXIP的表达水平与FGF4的表达水平呈正相关。然后，我们通过荧光素酶报告基因检测、逆转录-聚合酶链反应和蛋白质印迹分析，验证了HBXIP在启动子、mRNA和蛋白质水平上上调了FGF4的表达。此外，通过荧光素酶报告基因检测，我们发现HBXIP能够通过转录因子Sp1激活FGF4启动子。染色质免疫沉淀检测证实，HBXIP与Sp1共同激活以刺激FGF4启动子。在功能方面，通过伤口愈合和transwell细胞迁移检测，我们表明HBXIP通过FGF4促进乳腺癌细胞迁移。因此，我们得出结论，癌蛋白HBXIP通过激活转录因子Sp1上调FGF4，从而促进乳腺癌细胞的迁移。在治疗方面，HBXIP可能成为乳腺癌的一个新靶点。
