慢性缺氧应激可能通过EMT增强乳腺癌MCF-7细胞恶性生物学行为

目的:探讨慢性缺氧应激对人乳腺癌MCF-7细胞恶性生物学行为的影响及可能机制。方法:将人乳腺癌MCF-7细胞分为缺氧组(1%O_2、5%CO_2和94%N_2)和正常对照组(常氧)进行培养。利用MTT法、CCK-8实验、细胞直接计数法及细胞侵袭和迁移实验对MCF-7细胞活力、增殖及侵袭和迁移能力进行检测;用软琼脂集落形成实验及Matrigel 3D培养技术检测MCF-7细胞非锚定生长能力及极性改变情况;利用MCF-7细胞构建裸鼠皮下种植瘤模型,检测慢性缺氧应激对体内肿瘤生长及肺转移的影响;利用倒置显微镜观察MCF-7细胞形态改变;Western blot检测低氧诱导因子1(hypoxia-inducible factor-1,HIF-1)和磷酸化的糖原合成酶激酶3β(glycogen synthase kinase-3β,GSK-3β)在缺氧环境下表达水平的改变,以及E-钙黏连蛋白(E-cadherin)、N-钙黏连蛋白(Ncadherin)、波形蛋白(vimentin)、基质金属蛋白酶3(matrix metalloproteinase-3,MMP-3)、MMP-9等上皮-间充质转化(epithelial-mesenchymal transition,EMT)相关蛋白的表达水平。结果:与正常对照组相比较,慢性缺氧组MCF-7细胞活力、增殖能力及侵袭迁移能力增强,细胞非锚定生长能力提高且在3D培养系统更容易发生极性改变,呈现侵袭样生长,体内生长及转移能力增强;除了HIF-1被缺氧诱导表达升高外,GSK-3β呈现活化趋势,且上皮样标志物E-cadherin蛋白表达水平明显下降,而间充质样标志物N-cadherin、vimentin、MMP-3和MMP-9蛋白表达水平明显升高。结论:慢性缺氧应激促进了乳腺癌细胞恶性生物学行为,且其机制可能与EMT有关。

Chronic hypoxia enhances aggressiveness of MCF-7 breast cancer cells through EMT

AIM: To investigate the effects of chronic hypoxia on the aggressiveness of MCF-7, a human breast cancer cell line, and the underlying mechanisms.METHODS: MCF-7 cells were cultured under hypoxia (1% O₂, 5% CO₂ and 94% N₂) or control (95% O₂ and 5% CO₂) condition. The viability, proliferation, and invasion and migration abilities of the MCF-7 cells were determined by MTT assay, CCK-8 assay, cell counting, and cell invasion and migration assays. Anchorage-independent growth and the alteration of cellular polarization of the MCF-7 cells were tested by soft agar colony formation assay and Matrigel-3D culture assay, respectively. The effects of chronic hypoxia on the growth and metastasis of MCF-7 cells in vivo were investigated by xenograft in nude mice. The morphological changes of the MCF-7 cells were observed under an inverted microscope. Hypoxia-induced alterations in the levels of hypoxia inducible factor-1 (HIF-1) and phosphorylated glycogen synthase kinase-3β (p-GSK-3β) as well as epithelial-mesenchymal transition (EMT) molecules, such as E-cadherin, N-cadherin, vimentin, matrix metalloproteinase (MMP)-3 and MMP-9, were determined by Western blot.RESULTS: Chronic hypoxia significantly increased the viability, proliferation, and invasion and migration abilities of MCF-7 cells in vitro, enhanced the anchorage-independent growth, facilitated cellular polarization alteration in Matrigel-3D culture, and promoted cancer metastasis in vivo. Hypoxia up-regulated HIF-1, activated GSK-3β, down-regulated E-cadherin and increased the protein levels of N-cadherin, vimentin, MMP-3 and MMP-9. CONCLUSION: Chronic hypoxia enhances the aggressiveness of breast cancer cells probably through EMT.