Am J Cancer Res 2013;3(4):356-373

Original Article
Krüppel-like factor 8 promotes tumorigenic mammary stem cell induction by
targeting miR-146a

Xianhui Wang, Heng Lu, Tianshu Li, Lin Yu, Gang Liu, Xu Peng, Jihe Zhao

Burnett School of Biomedical Sciences, University of Central Florida, College of Medicine, Orlando, FL; Center for Cell Biology &
Cancer Research, Albany Medical College, Albany, NY; Department of Systems Biology and Translational Medicine, College of
Medicine, Texas A&M Health Science Center, Temple, TX

Received May 12, 2013; Accepted July 3, 2013; Epub August 14, 2013; Published August 30, 2013

Abstract: The properties of stem cells can be induced during the epithelial to mesenchymal transition (EMT). The responsible
molecular mechanisms, however, remain largely undefined. Here we report the identification of the microRNA-146a (miR-146a)
as a common target of Krüppel-like factor 8 (KLF8) and TGF-β, both of which are known EMT-inducers. Upon KLF8
overexpression or TGF-βtreatment, a significant portion of the MCF-10A cells gained stem cell traits as demonstrated by an
increased expression of CD44high/CD24low, activity of aldehyde dehydrogenase (ALDH), mammosphere formation and
chemoresistance. Along with this change, the expression of miR-146a was highly upregulated in the cells. Importantly, we found
that miR-146a was aberrantly co-overexpressed with KLF8 in a panel of invasive human breast cancer cell lines. Ectopic
expression of KLF8 failed to induce the stem cell traits in the MCF-10A cells if the cells were pre-treated with miR-146a inhibitor,
whereas overexpression of miR-146a in the MCF-10A cells alone was sufficient to induce the stem cell traits. Co-staining and
luciferase reporter analyses indicated that miR-146a targets the 3’-UTR of the Notch signaling inhibitor NUMB for translational
inhibition. Overexpression of KLF8 dramatically potentiated the tumorigenecity of MCF-10A cells expressing the H-Ras
oncogene, which was accompanied by a loss of NUMB expression in the tumors. Taken together, this study identifies a novel
role and mechanism for KLF8 in inducing pro-tumorigenic mammary stem cells via miR-146a potentially by activating Notch
signaling. This mechanism could be exploited as a therapeutic target against drug resistance of breast cancer. (ajcr0000206).

Keywords: KLF8, miR-146a, EMT, mammary stem cells, tumorigenesis

Address correspondence to: Jihe Zhao, Burnett School of Biomedical Sciences, University of Central Florida, College of
Medicine, 6900 Lake Nona Boulevard, Orlando, FL 32827. Tel: 407-266-7099; Fax: 407-266-7002; E-mail: Jihe.Zhao@ucf.edu;
Xu Peng, Department of Systems Biology and Translational Medicine, College of Medicine, Texas A&M Health Science Center,
702 Southwest H.K. Dodgen Loop, Temple, TX 76504. Tel: 254-742-7176; Fax: 254-742-7145; E-mail: xpeng@medicine.tamhsc.
edu
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American Journal of Cancer Research
ISSN: 2156-6976