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The high mortality rate in Breast Cancer (BC) is largely due to the difficulty of early detection and inadequate accuracy of the current diagnostic approaches. In this study, we investigated serum and tumor miRNA profiles of 1800 breast cancer miRNA expression profiles of GEO (Gene Expression Omnibus) and also more than 2500 patients in TCGA (The Cancer Genome Atlas) database. After data analysis by some packages like Limma, and WGCNA, we selected 6 hub miRNAs. Then by collecting serum samples of 100 breast cancer patients, real-time PCR was performed and the diagnosis performance of hub miRNAs was evaluated by ROC curve. Due to more validation, Kaplan-Meier Plot of hub miRNAs was evaluated by 1262 BC samples using METABRIC database. The target genes of 6 hub miRNAs were investigated using Mirbase, Mirtarbase, Targetscan, and TransmiR and after the identification of target genes, their expression was evaluated in 1600 BC samples using GEO database. Finally, six miRNAs including Hsa-miR-151a-5p, Hsa-miR-34a-5p, Hsa-miR-1307-3p, Hsa-miR-450b-5p, Hsa-miR-501-3p, and Hsa-miR-532-5p were introduced as effective biomarkers of BC.

The high mortality rate in Breast Cancer (BC) is largely due to the difficulty of early detection and inadequate accuracy of the current diagnostic approaches. MicroRNAs (miRNAs) are a class of non-coding RNAs characterized by their short length of 22 nucleotides-length, which have been found with regulatory functions in gene expression and their dysregulation are associated with a wide variety of human diseases such as various types of cancer including BC. In this study, we investigated serum and tumor miRNA profiles from more than 1500 breast cancer miRNA expression profiles from GEO and also more than 2500 patients by TCGA database. After data analysis by some packages like Limma, MetaDE, and WGCNA, we selected 6 hub miRNAs. Then by collecting serum samples of 100 breast cancer patients, real-time PCR was performed and the diagnosis performance of hub miRNAs was evaluated by ROC curve. Due to more validation, Kaplan-Meier Plot of hub miRNAs evaluated by 1262 BC samples using METABRIC database. Therefore by considering internationally and locally data, we succeeded to identify the more prevalent and effective breast cancer biomarkers including Hsa-miR-151a-5p, Hsa-miR-34a-5p, Hsa-miR-1307-3p, Hsa-miR-450b-5p, Hsa-miR-501-3p, and Hsa-miR-532-5p.

Doxorubicin (DOX) is an effective chemotherapy agent against a wide variety of tumors. However, intrinsic or acquired resistance diminishes the sensitivity of cancer cells to DOX, which leads to a cancer relapse and treatment failure. Resolutions to this challenge includes identification of the molecular pathways underlying DOX sensitivity/resistance and the development of innovative techniques to boost DOX sensitivity. DOX is classified as a Topoisomerase II poison, which is cytotoxic to rapidly dividing tumor cells. Molecular mechanisms responsible for DOX resistance include effective DNA repair and resumption of cell proliferation, deregulated development of cancer stem cell and epithelial to mesenchymal transition, and modulation of programmed cell death. MicroRNAs (miRNAs) have been shown to potentiate the reversal of DOX resistance as they have gene-specific regulatory functions in DOX-responsive molecular pathways. Identifying the dysregulation patterns of miRNAs for specific tumors following treatment with DOX facilitates the development of novel combination therapies, such as nanoparticles harboring miRNA or miRNA inhibitors to eventually prevent DOX-induced chemoresistance. In this article, we summarize recent findings on the role of miRNAs underlying DOX sensitivity/resistance molecular pathways. Also, we provide latest strategies for utilizing deregulated miRNA patterns as biomarkers or miRNAs as tools to overcome chemoresistance and enhance patient's response to DOX treatment.