MiR-422a weakened breast cancer stem cells properties by targeting PLP2

ABSTRACT

Objective: This study investigated miR-422a and PLP2 expressions in breast cancer cells and breast cancer stem cells (BCSCs). Besides, their influences on polymorphism changes were observed.

Methods: Flow cytometry and fluorescence-activated cell sorting was performed and CD24⁻/CD44⁺ cells were sorted from breast cancer cells and recognized as BCSCs. Microarray was applied to search for the differentially expressed miRNAs and mRNAs between MCF7 and BCSCs. The aberrant expression of miR-422a and PLP2 was further confirmed by RT-qPCR and the direct targeted relationship was verified by dual-luciferase reporter assay. After in vitro transfection, the expression of miR-422a and PLP2 were manipulated and biological functions of BMSCs were compared with CCK-8, colony formation and sphere formation assay. The tumorigenesis ability of transfected BMSCs was also investigated in NOD/SCID tumor mice models.

Results: BMSCs were successfully established from MCF7 cells and miR-422a expression was downregulated while PLP2 level decreased in BMSCs. MiR-422a directly targets the 3′UTR of PLP2 and suppressed its expression. Besides, the up-regulation of miR-422a contributed to weakened ability of proliferation and microsphere formation of BMSCs, while PLP2 overexpression facilitated those biological abilities. Tumorigenesis of BMSCs in mice models was impaired by either overexpression of miR-442a or silencing of PLP2.

Conclusion: Up-regulation of miR-422a attenuated microsphere formation, proliferation and tumor formation of breast cancer stem cells via suppressing the PLP2 expression.

KEYWORDS:

• breast cancer stem cells
• miR-422a
• PLP2

Author contribution

Yanmei Zou, Yuandong Chen and Shuo Yao contributed to research conception and design as well as manuscript drafting; Guangrui Deng, Dian Liu, Yihua Wang and Xun Yuan analysed and interpreted data; Shunfang Liu, Jie Rao and Huihua Xiong made statistical analysis; Xianglin Yuan, Shiying Yu, Feng Zhu and Hua Xiongrevised the manuscript and took the role of funding collectors. In addition, all authors approved final manuscript.

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Additional information

Funding

This study was supported by National Science Foundation Grant No. 81772827 for Yihua Wang; National Science Youth Foundation Grant No. 81502118 for Yanmei Zou; Natural Science Foundation of Hubei Province No. 2016CKB711 for Hua Xiong and No. 2016CFC761 for Yuandong Chen.