Spotlight on Exosomal Non-Coding RNAs in Breast Cancer: An In Silico Analysis to Identify Potential lncRNA/circRNA-miRNA-Target Axis.

Breast cancer (BC) has recently become the most common cancer type worldwide, with metastatic disease being the main reason for disease mortality. This has brought about strategies for early detection, especially the utilization of minimally invasive biomarkers found in various bodily fluids. Exosomes have been proposed as novel extracellular vesicles, readily detectable in bodily fluids, secreted from BC-cells or BC-tumor microenvironment cells, and capable of conferring cellular signals over long distances via various cargo molecules. This cargo is composed of different biomolecules, among which are the novel non-coding genome products, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and the recently discovered circular RNA (circRNA), all of which were found to be implicated in BC pathology. In this review, the diverse roles of the ncRNA cargo of BC-derived exosomes will be discussed, shedding light on their primarily oncogenic and additionally tumor suppressor roles at different levels of BC tumor progression, and drug sensitivity/resistance, along with presenting their diagnostic, prognostic, and predictive biomarker potential. Finally, benefiting from the miRNA sponging mechanism of action of lncRNAs and circRNAs, we established an experimentally validated breast cancer exosomal non-coding RNAs-regulated target gene axis from already published exosomal ncRNAs in BC. The resulting genes, pathways, gene ontology (GO) terms, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis could be a starting point to better understand BC and may pave the way for the development of novel diagnostic and prognostic biomarkers and therapeutics.

miR-126 Decreases Proliferation and Mammosphere Formation of MCF-7 and Predicts Prognosis of ER+ Breast Cancer.

Breast cancer (BC) is a major health burden that affects over one million women each year. It is the most prevalent cancer in women and the number one cancer killer of them worldwide. Of all BC subtypes, estrogen receptor-positive (ER+) BC is the most commonly diagnosed. The objective of this study is to investigate the contribution of miR-126 in the tumorigenesis of ER+ BC. miR-126 was downregulated in ER+ BC tissues from young breast cancer patients, as shown through miRNA microarray analysis and RT-qPCR. Subsequently, the effect of the modulation of miR-126 levels on the proliferation, cell cycle progression, and spheres formation of the ER+ BC cell line, MCF-7, was assessed by MTT assay, PI analysis, and mammosphere formation assay, respectively. miR-126 overexpression significantly decreased MCF-7 proliferation and mammosphere-forming ability, but did not affect cell cycle progression. Then, in silico analysis determined SLC7A5, PLXNB2, CRK, PLK2, SPRED1, and IRS1 as potential targets of miR-126. RT-qPCR data showed that miR-126 overexpression significantly downregulated SLC7A5 and PLXNB2 mRNA levels in MCF-7. Finally, in silico survival analysis showed that high expression of miR-126 or low expression of SLC7A5 correlated with better overall survival (OS) of ER+ BC patients. Overall, our study suggests that miR-126 might play a tumor suppressor role in ER+ BC. miR-126 and SLC7A5 might also be considered potential prognostic biomarkers in ER+ BC.

A Signature of Four Circulating microRNAs as Potential Biomarkers for Diagnosing Early-Stage Breast Cancer.

Breast cancer (BC) is the most predominant type of cancer among women. The aim of this study is to find new biomarkers that can help in early detection of BC, especially for those who are too young to be screened using mammography as per guidelines. Using microRNA microarray, we previously showed dysregulation of 74 microRNAs in tumors from early BC patients as compared with normal adjacent tissues, which we were interested in studying in blood circulation. In this study, we investigated the expression of 12 microRNA (miR-21/miR-155/miR-23a/miR-130a/miR-145/miR-425-5p/miR-139-5p/miR-451/miR-195/miR-125b/miR-100, and miR-182) in the plasma of 41 newly diagnosed Lebanese BC patients with early invasive ductal carcinoma as compared with 32 healthy controls. Total RNA was extracted from plasma, and expression levels of miRNA of interest were measured using RT-qPCR followed by statistical analysis; miR-21, miR-155, miR-23a, miR-130a, miR-145, miR-425-5p, and miR-139-5p were significantly upregulated and miR-451 was significantly downregulated, in the plasma of BC patients as compared with healthy controls. The positively correlated miR-23a, miR-21, and miR-130a had a high diagnostic accuracy (86%). Importantly, the combination of miR-145/miR-425-5p/miR-139-5p/miR-130a scored the highest diagnostic accuracy of 95% with AUC = 0.97 (sensitivity 97% and specificity 91%). MicroRNAs are promising non-invasive diagnostic biomarkers for early-stage BC with the panel of miR-145/miR-425-5p/miR-139-5p/miR-130a having the highest diagnostic accuracy.

Antitumor efficacy of arsenic/interferon in preclinical models of chronic myeloid leukemia resistant to tyrosine kinase inhibitors.

BACKGROUND: Tyrosine kinase inhibitors (TKIs) are the standard treatment for chronic myeloid leukemia (CML). Despite their clinical success, TKIs are faced with challenges such as treatment resistance, which may be driven by kinase domain mutations, and frequent disease relapse upon the cessation of treatment. The combination of arsenic trioxide (ATO) and interferon-α (IFN) was previously demonstrated to inhibit proliferation and induce apoptosis in CML cell lines, prolong the survival of primary wild-type CML mice, and dramatically decrease the activity of leukemia-initiating cells (LICs). METHODS: The ATO/IFN combination was tested in vitro on imatinib (IMN)-resistant K562-R and Ar230-R cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays were used to evaluate proliferation and apoptosis, respectively. The acridine orange assay was used to assess autophagy, and quantitative reverse transcription-polymerase chain reaction was used to assess the involvement of the hedgehog (Hh) pathway. In vivo, a retroviral transduction/transplantation T315I BCR-ABL CML mouse model was used to assay the effect of the treatment on survival, tumor burden (histopathology and blood counts), and LIC activity (secondary transplantation). RESULTS: In vitro, ATO/IFN synergized to inhibit proliferation and induce apoptosis of IMN-resistant cells with variant modes of resistance. Furthermore, the preclinical effects of ATO/IFN were associated with induction of autophagy along with inhibition of the Hh pathway. Most remarkably, ATO/IFN significantly prolonged the survival of primary T315I-CML mice and displayed a dramatic impairment of disease engraftment in secondary mice, which reflected decreased LIC activity. CONCLUSIONS: Collectively, the ATO/IFN strategy has been demonstrated to have the potential to lead to durable remissions in TKI-resistant CML preclinical models and to overcome various TKI-specific mechanisms of resistance.