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Title: Mirnome Profiling of Breast Cancer Cell Lines with Respect to Estrogen Receptor Status
Authors: Alyaa Abdullah Al-Ateyah 
Supervisor: Prof. Yunus Luqmani
Keywords: Breast Cancer, Estrogen Receptor
Issue Date: 2016
Publisher:  Kuwait university - college of graduate studies
Abstract: MicroRNAs (miRs) are a mechanism that regulates gene expression by binding to target mRNAs to prevent their translation. Mimicking or antagonizing their action presents novel opportunities for cancer therapy. We analyzed the miRnome profile of several human breast cancer cell lines to determine the influence of estrogen receptor (ER) silencing previously shown to result in epithelial to mesenchymal transition (EMT) and enhanced tumor invasion. MicroRNA extracted from MDA-MB-231 (de novo ER-) and ER-silenced (PII and IM- 26) or expressing (YS1.2) siRNA transfected derivatives of MCF7 cells was deep sequenced on Illumina NextSeq500. Respective miRnomes were compared with edgeR package in R and Venny2.1 and target prediction performed with miRTarBase. Mimics and inhibitors of selected differentially expressed miRs associated with EMT mediators (miR-200c-3p targeting ZEB1, -449a targeting δ-catenin and -29a-3p) were transfected into PII and YS1.2 cells and mRNA targets, as well as E-cadherin and keratin 19 as epithelial and vimentin as mesenchymal marker, measured using taqman PCR. Each line expressed about 20% of the total known human miRome; All 3 ER- cells exhibited high degree of similarity. Out of these expressed miRs, 50-60% of were significantly differentially expressed between ER- and ER+ cells. Transfection of miR-200c-3p mimic into PII cells down regulated ZEB1 and increased E-cadherin and keratin 19 with accompanying morphological changes all reflecting a reversal back into an epithelial phenotype. On the other hand, transfecting YS1.2 with miR-449a mimic down regulated δ-catenin but did not induce EMT. Transfecting both cell lines with the mimic or inhibitor of miR-29a-3p showed no change in epithelial to mesenchymal markers suggesting that the EMT induced by loss of ER function can be reversed by blocking some but not just any random EMT-associated genes. These data suggest that differences in miR expression can be exploited not only as mediators (using mimics) and targets (using miR antagonists) for general cancer therapies aimed at regulating either individual or multiple mRNAs but also to re-sensitise endocrine resistant breast cancers by turning them back into a type that will be susceptible to endocrine agents.
Appears in Programs:2050 Molecular Biology

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