Generation of the MCF-7 cell sublines with CRISPR/Cas9 mediated disruption of estrogen receptor alfa (ESR1) expression

Supported by the literature, our initial hypothesis was that Estrogen Receptor alfa (ESR1) may function as a master regulator by influencing the expression of epithelial-to-mesenchymal transition (EMT)-related genes in cancer cells. To explore this further, we used the CRISPR/Cas9 gene editing system to create MCF-7 sublines with down-regulated ESR1 expression and analyzed its impact on EMT initiation. By applying two distinct types of gRNA for gene editing, we established six MCF-7 cell sublines with either nearly complete or partial down-regulation of the ESR1 isoforms. Unexpectedly, the data obtained revealed no discernible impact of ESR1 down-regulation on EMT manifestation as Western blot and Real-Time qPCR analysis of selected clones revealed no changes in EMT markers expression. We suggested that those of the ESR1 isoforms, the expression of which was not affected by gene editing, could be crucial for the initiation of EMT. The obtained cell models will be used further to evaluate the activity of ESR1 isoforms. Keywords: CRISPR/Cas9, epithelial-to-mesenchymal transition, estrogen receptor alfa, MCF-7 cells