Department of Medicine, University of Illinois, Chicago, Illinois 60612.
Department of Medicine, University of Illinois, Chicago, Illinois 60612; Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607.
J Biol Chem. 2011 Dec 2;286(48):41425-41433. doi: 10.1074/jbc.M111.270843. Epub 2011 Oct 6.
Using mass spectrometric analysis we found that oncogenic transcription factor FOXM1 that is overexpressed in a majority of human cancers interacts with multifunctional protein NPM, which is also overexpressed in a variety of human tumors. Coimmunoprecipitation and glutathione S-transferase pull-down experiments demonstrated that NPM forms a complex with FOXM1 and also identified the regions responsible for their interaction. Immunofluorescence microscopy confirmed the interaction between FOXM1 and NPM in cancer and immortal cells. Furthermore, knockdown of NPM in immortal and cancer cells led to significant down-regulation of FOXM1 similar to its levels in normal cells, suggesting that NPM might modulate FOXM1 level. In addition, in OCI/AML3 leukemia cells where mutant NPM is localized in the cytoplasm we found that typically nuclear FOXM1 was predominantly co-localized with NPM in the cytoplasm, while NPM knockdown led to the disappearance of FOXM1 from the cytoplasm, suggesting that NPM may also determine intracellular localization of FOXM1. Knockdown of FOXM1 or NPM in MIA PaCa-2 pancreatic cancer cells inhibited anchorage-dependent and independent growth in cell culture, and tumor growth in nude mice. In addition, over-expression of FOXM1 reversed the effect of NPM knockdown in vitro. Our data suggest that in cancer cells NPM interacts with FOXM1 and their interaction is required for sustaining the level and localization of FOXM1. Targeting the interaction between FOXM1 and NPM by peptides or small molecules may represent a novel therapeutic strategy against cancer.
使用质谱分析，我们发现致癌转录因子 FOXM1 在大多数人类癌症中过度表达，与多功能蛋白 NPM 相互作用，NPM 也在多种人类肿瘤中过度表达。共免疫沉淀和谷胱甘肽 S-转移酶 pull-down 实验表明，NPM 与 FOXM1 形成复合物，并确定了它们相互作用的区域。免疫荧光显微镜证实了 FOXM1 和 NPM 在癌症和永生化细胞中的相互作用。此外，在永生化和癌细胞中敲低 NPM 导致 FOXM1 的显著下调，类似于正常细胞中的水平，表明 NPM 可能调节 FOXM1 水平。此外，在 OCI/AML3 白血病细胞中，突变型 NPM 定位于细胞质中，我们发现通常位于核内的 FOXM1 主要与细胞质中的 NPM 共定位，而 NPM 敲低导致 FOXM1 从细胞质中消失，表明 NPM 还可能决定 FOXM1 的细胞内定位。在 MIA PaCa-2 胰腺癌细胞中敲低 FOXM1 或 NPM 抑制了细胞培养中的锚定依赖性和非依赖性生长，以及裸鼠中的肿瘤生长。此外，FOXM1 的过表达逆转了 NPM 敲低的体外效应。我们的数据表明，在癌细胞中，NPM 与 FOXM1 相互作用，它们的相互作用对于维持 FOXM1 的水平和定位是必需的。通过肽或小分子靶向 FOXM1 和 NPM 之间的相互作用可能代表一种针对癌症的新治疗策略。
