Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, PR China.
Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, PR China.
Life Sci. 2020 Jul 15;253:117722. doi: 10.1016/j.lfs.2020.117722. Epub 2020 Apr 26.
It is well known that pyruvate dehydrogenase kinase 1 (PDK1) is highly expressed in breast cancer (BC) tissues and promotes tumor growth, but the underlying mechanisms of this process are unclear. Here, we investigated the effects of nuclear PDK1 on growth, migration and invasion in human BC cells.
The sub-cellular localization of PDK1 in BC cells was performed with subcellular fractionation followed by Western blot and immunofluorescence. The localization of PDK1 in breast normal tissue and breast duct carcinoma was detected by Immunohistochemistry. Then the protein-protein interaction between PDK1 and Importin β was verified by co-immunoprecipitation assay. Finally, the effects of nuclear PDK1 on cell proliferation, apoptosis, migration and invasion of BC cells were assessed.
In addition to its well-known sub-cellular localization, PDK1 was present in the nucleus of BC cells, and EGF treatment increased nucleus distribution of PDK1. Moreover, the level of nuclear PDK1 accumulation facilitated the growth of BC cells. We also found that the entry of PDK1 into nucleus mainly relied on the nuclear localization signal (NLS), and NLS mutation inhibited the entry of PDK1 into nucleus; as a result, the migration and invasion abilities of BC cells were impaired, and the number of apoptotic cells was significantly increased.
Our findings provided a new supplement to the sub-cellular localization of PDK1 in BC cells and uncovered the function of nuclear PDK1 in facilitating BC cells growth, migration and invasion.
众所周知，丙酮酸脱氢酶激酶 1（PDK1）在乳腺癌（BC）组织中高度表达，并促进肿瘤生长，但这一过程的潜在机制尚不清楚。在这里，我们研究了核 PDK1 对人 BC 细胞生长、迁移和侵袭的影响。
采用亚细胞分级分离结合 Western blot 和免疫荧光法检测 PDK1 在 BC 细胞中的亚细胞定位。免疫组织化学检测乳腺正常组织和乳腺导管癌中 PDK1 的定位。然后通过共免疫沉淀实验验证 PDK1 与 Importin β 之间的蛋白-蛋白相互作用。最后，评估核 PDK1 对 BC 细胞增殖、凋亡、迁移和侵袭的影响。
除了众所周知的亚细胞定位外，PDK1 还存在于 BC 细胞的细胞核中，EGF 处理增加了 PDK1 的核分布。此外，核 PDK1 积累水平促进了 BC 细胞的生长。我们还发现，PDK1 进入细胞核主要依赖于核定位信号（NLS），NLS 突变抑制了 PDK1 进入细胞核；结果，BC 细胞的迁移和侵袭能力受损，凋亡细胞数量明显增加。
我们的研究结果为 PDK1 在 BC 细胞中的亚细胞定位提供了新的补充，并揭示了核 PDK1 促进 BC 细胞生长、迁移和侵袭的功能。
