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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

The miR-125b-1 precursor and mature transcript are downregulated in the MCF7 breast cancer cell line. We evaluated the expression levels of pri-miR-125b-1 and mature miR-125b in the MCF10A non-transformed breast cell line and the two breast cancer cell lines MCF7 and MDA-MB-231. *p > 0.001
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Fig1: The miR-125b-1 precursor and mature transcript are downregulated in the MCF7 breast cancer cell line. We evaluated the expression levels of pri-miR-125b-1 and mature miR-125b in the MCF10A non-transformed breast cell line and the two breast cancer cell lines MCF7 and MDA-MB-231. *p > 0.001

Mentions: miR-125b (mature miRNA) is transcribed from two different genes: miR-125b-1 (chromosome 11) and miR-125b-2 (chromosome 21). However, the transcriptional activity of miR-125b-2 is low (Additional file 1: Fig. 1). Thus, most miR-125b is derived from the miR-125b-1 gene. To determine miR-125b-1 expression levels, we evaluated pri-miRNA and mature miRNA levels in the breast cancer cell lines MCF7 and MDA-MB-231 by qRT-PCR compared with the non-transformed breast cell line MCF10A. pri-miR-125b-1 levels in MCF7 and MDA-MB-231 cells were reduced by 99 and 72 %, respectively, compared with MCF10A cells. However, mature miR-125b levels were reduced only in MCF7 cells. In MDA-MB-231 cells, mature miR-125b levels were increased by nearly threefold (Fig. 1). This increment of miR-125b in MDA-MB-231 cells may be associated with the accumulation of miRNA transcripts.Fig. 1


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

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

The miR-125b-1 precursor and mature transcript are downregulated in the MCF7 breast cancer cell line. We evaluated the expression levels of pri-miR-125b-1 and mature miR-125b in the MCF10A non-transformed breast cell line and the two breast cancer cell lines MCF7 and MDA-MB-231. *p > 0.001
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4930440&req=5

Fig1: The miR-125b-1 precursor and mature transcript are downregulated in the MCF7 breast cancer cell line. We evaluated the expression levels of pri-miR-125b-1 and mature miR-125b in the MCF10A non-transformed breast cell line and the two breast cancer cell lines MCF7 and MDA-MB-231. *p > 0.001
Mentions: miR-125b (mature miRNA) is transcribed from two different genes: miR-125b-1 (chromosome 11) and miR-125b-2 (chromosome 21). However, the transcriptional activity of miR-125b-2 is low (Additional file 1: Fig. 1). Thus, most miR-125b is derived from the miR-125b-1 gene. To determine miR-125b-1 expression levels, we evaluated pri-miRNA and mature miRNA levels in the breast cancer cell lines MCF7 and MDA-MB-231 by qRT-PCR compared with the non-transformed breast cell line MCF10A. pri-miR-125b-1 levels in MCF7 and MDA-MB-231 cells were reduced by 99 and 72 %, respectively, compared with MCF10A cells. However, mature miR-125b levels were reduced only in MCF7 cells. In MDA-MB-231 cells, mature miR-125b levels were increased by nearly threefold (Fig. 1). This increment of miR-125b in MDA-MB-231 cells may be associated with the accumulation of miRNA transcripts.Fig. 1

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