MiR‐21 regulates epithelial‐mesenchymal transition phenotype and hypoxia‐inducible factor‐1α expression in third‐sphere forming breast cancer stem cell‐like cells

Mar 23, 2012Cancer science

MiR-21 controls cell changes and low-oxygen response in breast cancer stem-like cells forming 3D clusters

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Abstract

Third-sphere forming CSC-like cells exhibited elevated markers and enhanced migration and invasion capacities.

CSCs may drive tumor progression due to their stem-like properties.
Epithelial-mesenchymal transition (EMT) was induced in CSC-like cells, indicated by increased mesenchymal markers and decreased epithelial markers.
HIF-1α and miR-21 levels were found to be upregulated in CSC-like cells.
Inhibition of miR-21 reversed EMT and reduced HIF-1α expression, along with decreased cell invasion and migration.
The findings suggest that miR-21 plays a critical role in regulating CSC features associated with EMT.

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Cancer stem cells (CSCs) are predicted to be critical drivers of tumor progression due to their "stemness", but the molecular mechanism of CSCs in regulating metastasis remains to be elucidated. Epithelial-mesenchymal transition (EMT), hypoxia-inducible factor (HIF)-1α, and miR-21, all of which contribute to cell migration for metastasis, are interrelated with CSCs. In the present study, third-sphere forming (3-S) CSC-like cells, which showed elevated CSC surface markers (ALDH1(+) and CD44(+)/CD24(-/low)) and sphereforming capacity as well as migration and invasion capacities, were cultured and isolated from breast cancer MCF-7 parental cells, to evaluate the role of miR-21 in regulating the CSC-like cell biological features, especially EMT. EMT, which was assessed by overexpression of mesenchymal cell markers (N-cadherin, Vimentin, alpha-smooth muscle actin [α-SMA]) and suppression of epithelial cell marker (E-cadherin), was induced in 3-S CSC-like cells. Moreover, both of HIF-1α and miR-21 were upregulated in the CSC-like cells. Interestingly, antagonism of miR-21 by antagomir led to reversal of EMT, downexpression of HIF-1α, as well as suppression of invasion and migration, which indicates a key role of miR-21 involved in regulate CSC-associated features. In conclusion, we demonstrated that the formation of CSC-like cells undergoing process of EMT-like associated with overexpression of HIF-1α, both of which are regulated by miR-21.

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MiR‐21 regulates epithelial‐mesenchymal transition phenotype and hypoxia‐inducible factor‐1α expression in third‐sphere forming breast cancer stem cell‐like cells

Abstract

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