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miR-125b-1 is repressed by histone modifications in breast cancer cell lines.

Cisneros-Soberanis F, Andonegui MA, Herrera LA - Springerplus (2016)

Bottom Line: In this work we investigated the effect of histone modifications on the regulation of this gene promoter.H3K27me3 and H3K9me3 were enriched in MCF7 and MDA-MB-231 cells, respectively.We over-expressed KDM4B/JMJD2B to reactivate this miRNA, resulting in a three-fold increase in miR-125b expression compared with the same cell line without KDM4B/JMJD2B over-expression.

View Article: PubMed Central - PubMed

Affiliation: Unidad de Investigación Biomédica en Cáncer, Instituto Nacional de Cancerología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Avenida San Fernando 22, Mexico City, 14080 Mexico.

ABSTRACT

Purpose: Downregulation of miR-125b-1 is associated with poor prognosis in breast cancer patients. In this work we investigated the effect of histone modifications on the regulation of this gene promoter.

Methods and results: We evaluated the enrichment of two histone modifications involved in gene repression, H3K9me3 and H3K27me3, on the miR-125b-1 promoter in two breast cancer cell lines, MCF7 (luminal A subtype) and MDA-MB-231 (triple-negative subtype), compared to the non-transformed breast cell line MCF10A. H3K27me3 and H3K9me3 were enriched in MCF7 and MDA-MB-231 cells, respectively. Next, we used an EZH2 inhibitor to examine the reactivation of miR-125b-1 in MCF7 cells and evaluated the transcriptional levels of pri-miR-125b-1 and mature miR-125b by qRT-PCR. pri-miRNA and mature miRNA transcripts were both increased after treatment of MCF7 cells with the EZH2 inhibitor, whereas no effect on miR-125b-1 expression levels was observed in MDA-MB-231 and MCF10A cells. We subsequently evaluated the effect of miR-125b-1 reactivation on the expression and protein levels of BAK1, a target of miR-125b. We observed 60 and 70 % decreases in the expression and protein levels of BAK1, respectively, compared to cells that were not treated with the EZH2 inhibitor. We over-expressed KDM4B/JMJD2B to reactivate this miRNA, resulting in a three-fold increase in miR-125b expression compared with the same cell line without KDM4B/JMJD2B over-expression.

Conclusion: The miR-125b-1 is repressed by different epigenetic mechanisms depending on the breast cancer subtype and that miR-125b-1 reactivation specifically eliminates the effect of repressive histone modifications on the expression of an pro-apoptotic target.

No MeSH data available.


Related in: MedlinePlus

JMJD2B over-expression reactivates miR-125b in MDA-MB-231 breast cancer cells. To determine if H3K9me3 is involved in miR-125b-1 repression, we over-expressed JMJD2B in MCF10A and MDA-MB-231 breast cells and then selected cells over-expressing JMJD2B by sorting (a). After the selection, we evaluated the expression levels of miR-125b (b)
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Fig3: JMJD2B over-expression reactivates miR-125b in MDA-MB-231 breast cancer cells. To determine if H3K9me3 is involved in miR-125b-1 repression, we over-expressed JMJD2B in MCF10A and MDA-MB-231 breast cells and then selected cells over-expressing JMJD2B by sorting (a). After the selection, we evaluated the expression levels of miR-125b (b)

Mentions: To determine the role of H3K9me3 in MDA-MB-231 cells, we over-expressed KDM4B/JMJD2B to reduce global levels of H3K9me3 histone modification in MCF10A and MDA-MB-231 cells. We specifically selected transfected cells over-expressing KDM4B/JMJD2B by cell sorting (Fig. 3a). Subsequent qRT-PCR analysis revealed a three-fold increase in miR-125b levels in KDM4B/JMJD2B-transfected MDA-MB-231 cells compared with MDA-MB-231 cells transfected with empty vector. However, no significant differences in miR-125b levels were observed between KDM4B/JMJD2B-transfected MCF10A cells and empty vector-transfected MDA-MB-231 cells (Fig. 3b).Fig. 3


miR-125b-1 is repressed by histone modifications in breast cancer cell lines.

Cisneros-Soberanis F, Andonegui MA, Herrera LA - Springerplus (2016)

JMJD2B over-expression reactivates miR-125b in MDA-MB-231 breast cancer cells. To determine if H3K9me3 is involved in miR-125b-1 repression, we over-expressed JMJD2B in MCF10A and MDA-MB-231 breast cells and then selected cells over-expressing JMJD2B by sorting (a). After the selection, we evaluated the expression levels of miR-125b (b)
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4930440&req=5

Fig3: JMJD2B over-expression reactivates miR-125b in MDA-MB-231 breast cancer cells. To determine if H3K9me3 is involved in miR-125b-1 repression, we over-expressed JMJD2B in MCF10A and MDA-MB-231 breast cells and then selected cells over-expressing JMJD2B by sorting (a). After the selection, we evaluated the expression levels of miR-125b (b)
Mentions: To determine the role of H3K9me3 in MDA-MB-231 cells, we over-expressed KDM4B/JMJD2B to reduce global levels of H3K9me3 histone modification in MCF10A and MDA-MB-231 cells. We specifically selected transfected cells over-expressing KDM4B/JMJD2B by cell sorting (Fig. 3a). Subsequent qRT-PCR analysis revealed a three-fold increase in miR-125b levels in KDM4B/JMJD2B-transfected MDA-MB-231 cells compared with MDA-MB-231 cells transfected with empty vector. However, no significant differences in miR-125b levels were observed between KDM4B/JMJD2B-transfected MCF10A cells and empty vector-transfected MDA-MB-231 cells (Fig. 3b).Fig. 3

Bottom Line: In this work we investigated the effect of histone modifications on the regulation of this gene promoter.H3K27me3 and H3K9me3 were enriched in MCF7 and MDA-MB-231 cells, respectively.We over-expressed KDM4B/JMJD2B to reactivate this miRNA, resulting in a three-fold increase in miR-125b expression compared with the same cell line without KDM4B/JMJD2B over-expression.

View Article: PubMed Central - PubMed

Affiliation: Unidad de Investigación Biomédica en Cáncer, Instituto Nacional de Cancerología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Avenida San Fernando 22, Mexico City, 14080 Mexico.

ABSTRACT

Purpose: Downregulation of miR-125b-1 is associated with poor prognosis in breast cancer patients. In this work we investigated the effect of histone modifications on the regulation of this gene promoter.

Methods and results: We evaluated the enrichment of two histone modifications involved in gene repression, H3K9me3 and H3K27me3, on the miR-125b-1 promoter in two breast cancer cell lines, MCF7 (luminal A subtype) and MDA-MB-231 (triple-negative subtype), compared to the non-transformed breast cell line MCF10A. H3K27me3 and H3K9me3 were enriched in MCF7 and MDA-MB-231 cells, respectively. Next, we used an EZH2 inhibitor to examine the reactivation of miR-125b-1 in MCF7 cells and evaluated the transcriptional levels of pri-miR-125b-1 and mature miR-125b by qRT-PCR. pri-miRNA and mature miRNA transcripts were both increased after treatment of MCF7 cells with the EZH2 inhibitor, whereas no effect on miR-125b-1 expression levels was observed in MDA-MB-231 and MCF10A cells. We subsequently evaluated the effect of miR-125b-1 reactivation on the expression and protein levels of BAK1, a target of miR-125b. We observed 60 and 70 % decreases in the expression and protein levels of BAK1, respectively, compared to cells that were not treated with the EZH2 inhibitor. We over-expressed KDM4B/JMJD2B to reactivate this miRNA, resulting in a three-fold increase in miR-125b expression compared with the same cell line without KDM4B/JMJD2B over-expression.

Conclusion: The miR-125b-1 is repressed by different epigenetic mechanisms depending on the breast cancer subtype and that miR-125b-1 reactivation specifically eliminates the effect of repressive histone modifications on the expression of an pro-apoptotic target.

No MeSH data available.


Related in: MedlinePlus