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J Breast Cancer. 2016 Jun;19(2):148-55. doi: 10.4048/jbc.2016.19.2.148. Epub 2016 Jun 24.

Aberrant Expression of Breast Development-Related MicroRNAs, miR-22, miR-132, and miR-212, in Breast Tumor Tissues.

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Department of Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Department of Genetics, Faculty of Biological Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran.; Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran.
Pathology Laboratory, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Human Genetic Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.



MicroRNAs (miRNAs) are a major class of small endogenous RNA molecules that posttranscriptionally regulate the expression of most genes in the human genome. miRNAs are often located in chromosomal fragile sites, which are suscept-ible to amplification or deletion. Chromosomal deletions are frequent events in breast cancer cells. Deletion and loss of heterozygosity at 17p13.3 have been reported in 49% of breast cancers. The aim of the current study was to evaluate potential expression alterations of miR-22, miR-132, and miR-212, which are located on the 17p13.3 locus and are required for mammary gland development.


A matched case-control study was conducted, which included 36 pairs of tumor and matched nontumor surgical specimens from patients diagnosed with breast invasive ductal carcinoma. Formalin-fixed paraffin-embedded samples from archival collections at the pathology department of Shariati Hospital were prepared for RNA extraction using the xylene-ethanol method before total RNA was isolated with TRIzol Reagent. Specific primers were designed for cDNA synthesis and miRNA amplification. The expression of miRNAs was then evaluated by real-time polymerase chain reaction (RT-PCR).


According to our RT-PCR data, the miR-212/miR-132 family was downregulated in breast cancer (0.328-fold, p<0.001), and this reduced expression was the most prominent in high-grade tumors. In contrast, miR-22 exhibited a significant upregulation in breast tumor samples (2.183-fold, p=0.040).


Consistent with the frequent deletion of the 17p13.3 locus in breast tumor cells, our gene expression data demonstrated a significant downregulation of miR-212 and miR-132 in breast cancer tissues. In contrast, we observed a significant upregulation of miR-22 in breast tumor samples. The latter conflicting result may have been due to the upregulation of miR-22 in stromal/cancer-associated fibroblasts, rather than in the tumor cells.


Biomarkers; Breast neoplasms; Chromosome deletion; MicroRNAs

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