Comparative Analysis of Micrornas Expression Between Tumor and Normal Breast Tissue in Patients with Invasive Ductal Carcinoma

Abstract

INTRODUCTION: MicroRNAs are small non-coding RNAs of 19-22 nucleotides, which regulate gene expression through mechanisms such as incomplete pairing and post-transcriptional gene silencing, repressing the translation of the mRNA target. Although they don’t have the property of coding for protein, such molecules have been recognized as one of the main regulators of genes encoding the human genome. They became part of the RNA-induced silencing complex and repress the translation of RNA by binding to the 3 UTR region homologous in a faulty connection. In recent years, in addition to the identification of microRNAs, about 1000 in humans, increasing information about the target and biological function has been accumulated exponentially. MicroRNAs influence the expression of genes that regulate cell proliferation, migration and apoptosis, acting as oncogene or tumor suppressor. MATERIAL AND METHODS: Were evaluated and compared for expression of microRNAs in paraffin material of 11 samples of tissue (08 being diagnosed with invasive ductal breast carcinoma and 3 of normal breast tissue). The expression analysis was performed using the miScript miRNA PCR System (Qiagen) containing 84 miRNAs for breast cancer. The samples were deparaffinized and extraction of total RNA was performed using MiRNeasy FFPE kit. The next step was convertion into cDNA using the MiScript II RT Kit, followed by PCR amplification with the MiScript SYBR Green PCR Kit. The reactions were packed in specific plates that were analyzed using the 7500 Real Time PCR System (MIHS 90ZA). Statistical analysis was performed using software MIScript miRNA PCR Array Data Analysis Tool. RESULTS: Cases were divided into two groups: tumor and normal breast. 17 microRNAs were overexpressed in tumor tissue and 06 microRNAs were hypoexpressed (p <0. 05). Let - 7g, mir-141, miR-15-A, miR-15-B, miR 16, mir 181 a, mir 181c, mir 193b, mir 199a-5p, mir 200a, mir 200b, mir 21, mir210, mir22, mir 27-A, mir 340, miR 429 were upregulated. Mir 125b, miR-125b-1*, mir 145, miR 204, miR 328, miR 489 were down regulated. DISCUSSION: Previous studies have analyzed the expression of miRNA and the results clearly distinguished the healthy tissue and breast cancer and the most aberrant miRNAs were miR-125b, mir-145, mir-21 and mir-155. CONCLUSION: Our series also evaluated and found overexpression of microRNAs in tumor tissues statistically significant in miR-125b, miR-145 and miR-21. It seems likely that the expression levels of miRNA can be used as new diagnostic markers and can thus provide a new approach for therapeutic intervention.