Chronic hypoxia enhances aggressiveness of MCF-7 breast cancer cells through EMT / 中国病理生理杂志

ABSTRACT

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 metas-tasis 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) mol-ecules, 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-regu-lated 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 .