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MiR-10b expression in breast cancer stem cells supports self-renewal through negative PTEN regulation and sustained AKT activation.

ABSTRACT: Cancer stem cells (CSCs) are linked to metastasis. Moreover, a discrete group of miRNAs (metastamiRs) has been shown to promote metastasis. Accordingly, we propose that miRNAs that function as metastatic promoters may influence the CSC phenotype. To study this issue, we compared the expression of 353 miRNAs in CSCs enriched from breast cancer cell lines using qRT-PCR analysis. One of the most altered miRNAs was miR-10b, which is a reported promoter of metastasis and migration. Stable overexpression of miR-10b in MCF-7 cells (miR-10b-OE cells) promoted higher self-renewal and expression of stemness and epithelial-mesenchymal transition (EMT) markers. In agreement with these results, inhibiting miR-10b expression using synthetic antisense RNAs resulted in a decrease in CSCs self-renewal. Bioinformatics analyses identified several potential miR-10b mRNA targets, including phosphatase and tensin homolog (PTEN), a key regulator of the PI3K/AKT pathway involved in metastasis, cell survival, and self-renewal. The targeting of PTEN by miR-10b was confirmed using a luciferase reporter, qRT-PCR, and Western blot analyses. Lower PTEN levels were observed in CSCs, and miR-10b depletion not only increased PTEN mRNA and protein expression but also decreased the activity of AKT, a downstream PTEN target kinase. Correspondingly, PTEN knockdown increased stem cell markers, whereas AKT inhibitors compromised the self-renewal ability of CSCs and breast cancer cell lines overexpressing miR-10b. In conclusion, miR-10b regulates the self-renewal of the breast CSC phenotype by inhibiting PTEN and maintaining AKT pathway activation.

SUBMITTER: Bahena-Ocampo I

PROVIDER: S-EPMC5341522 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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miR-10b expression in breast cancer stem cells supports self-renewal through negative PTEN regulation and sustained AKT activation.

Bahena-Ocampo Ivan I Espinosa Magali M Ceballos-Cancino Gisela G Lizarraga Floria F Campos-Arroyo Denise D Schwarz Angela A Maldonado Vilma V Melendez-Zajgla Jorge J Garcia‐Lopez Patricia P

EMBO reports 20160409 5

Cancer stem cells (CSCs) are linked to metastasis. Moreover, a discrete group of miRNAs (metastamiRs) has been shown to promote metastasis. Accordingly, we propose that miRNAs that function as metastatic promoters may influence the CSC phenotype. To study this issue, we compared the expression of 353 miRNAs in CSCs enriched from breast cancer cell lines using qRT-PCR analysis. One of the most altered miRNAs was miR-10b, which is a reported promoter of metastasis and migration. Stable overexpress ...[more]

PMID: 27113763

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Project description:Background Few reports have addressed the mechanism by which microRNA miR-10b-5p regulates post-myocardial infarction (post-MI) cardiomyocyte apoptosis under hypoxic conditions. Methods and Results C57BL/6 mice underwent surgical ligation of the left anterior descending artery to create an MI or ischemia/reperfusion animal model. The expression of miR-10b-5p, PTEN (phosphatase and tensin homolog), and HIF-1? (hypoxia-inducible factor 1?) was detected in infarct border zone tissues at various time points. After precordial injections of the negative control or miR-10b-5p, overexpression lentiviruses were made in the areas surrounding the MI sites at 1 week, and myocardial infarct size, cardiac function, and cardiomyocyte apoptosis were examined. A miR-10b-5p mimic was transfected into primary mouse cardiomyocytes to analyze its effects on cardiomyocyte apoptosis and PTEN expression. Meanwhile, PTEN as a target of miR-10b-5p was verified via luciferase reporter gene assays. Cotransfection of miR-10b-5 and PTEN verified the relationship between miR-10b-5 and PTEN. Under hypoxic stress, the expression of HIF-1? and miR-10b-5p was examined. The results showed that miR-10b-5p expression was markedly reduced in the infarct border zone. Overexpression of miR-10b-5p in the murine model of MI significantly reduced MI size, improved cardiac function, and inhibited apoptosis. Overexpression of miR-10b-5p in vitro antagonized hypoxia-induced cardiomyocyte apoptosis and specifically inhibited the expression of the apoptosis-related gene PTEN, but overexpression of PTEN weakened these effects. We also found that hypoxia-induced accumulation of HIF-1? resulted in decreased expression of miR-10b-5p. Interfering with the activation of the HIF-1? signaling pathway promoted Pri-miR-10b and miR-10b-5p expression and inhibited PTEN expression. Conclusions MicroRNA miR-10b-5p antagonizes hypoxia-induced cardiomyocyte apoptosis, indicating that miR-10b-5p may serve as a potential future clinical target for the treatment of MI.

Project description:Familial triple-negative breast cancers are often linked to mutations in the BRCA1 tumor suppressor gene. In sporadic triple-negative breast cancers BRCA1 is frequently inactivated at the transcriptional level, and it has been reported that this inactivation may be brought about by promoter methylation. More recently, it was found that BRCA1 may also be regulated at the post-transcriptional level by miRNAs. Here, we explored the expression of putative BRCA1-regulating miRNAs in sporadic human triple-negative breast cancer cells.Nine sporadic human breast cancer-derived cell lines and one benign breast epithelium-derived cell line were assessed for their hormone receptor, growth factor receptor and cytokeratin status by immunocytochemistry. The expression of 5 selected miRNAs predicted to target BRCA1 was assessed using qRT-PCR in the 10 cell lines. In addition, expression profiles of 84 known breast cancer-associated miRNAs were established in these 10 cell lines using PCR Array and qRT-PCR, respectively. The putative role of pre-selected candidate miRNAs in breast cancer development was assessed through exogenous expression of these miRNAs and their anti-miRNAs ('antagomirs') in MDA-MB-231 and MCF7 breast cancer-derived cells.Based on our expression profiling results, four candidate miRNAs (miR-10b, miR-26a, miR-146a and miR-153) were selected as being potentially involved in triple-negative breast cancer development. Exogenous expression assays revealed that miR-10b and miR-26a, but not miR-146a, can down-regulate the expression of BRCA1 in both triple-negative MDA-MB-231 and luminal epithelial MCF7 breast cancer-derived cells, whereas miR-153 could down-regulate BRCA1 expression only in MCF7 cells. In silico analysis of The Cancer Genome Atlas (TCGA) data confirmed that miR-146a is significantly higher expressed in triple-negative breast tumors compared to other (non triple-negative) breast tumors.Our work provides evidence for the involvement of specific miRNAs in triple-negative breast cancer development through regulating BRCA1 expression.

Dataset Information

MiR-10b expression in breast cancer stem cells supports self-renewal through negative PTEN regulation and sustained AKT activation.

Publications

miR-10b expression in breast cancer stem cells supports self-renewal through negative PTEN regulation and sustained AKT activation.

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