Self-assembled DNA nanostructure containing oncogenic miRNA-mediated cell proliferation by downregulation of FOXO1 expression

Abstract

Abstract FOXO1 transcription factor is not only limit the cell cycle progression but also promote cell death as a tumor suppressor protein. Though the expression of FOXO1 is largely examined in breast cancer, the regulation of FOXO1 by miRNA is yet to be explored. In the current study, self-assembled branched DNA (bDNA) nanostructures containing oncogenic miRNAs were designed and transfected to MCF7 cell lines to decipher the FOXO1 expression. bDNA containing oncogenic miRNA 27a, 96 and 182 synergistically downregulate the expression of FOXO1 in MCF7 cells. The down-regulation is evident both in mRNA and protein level suggesting bDNA having miRNA sequences can selectively bind to mRNA and inhibit translation. Secondly, the downstream gene expression of P21 and P27 are also significantly downregulated in presence of miR-bDNA nanostructures. The cell proliferation activity was progressively increased in presence of miR-bDNA nanostructure which confirms the reduced tumor suppression activity of FOXO1 and the downstream gene expression. This finding can be explored to design novel bDNA structures which can downregulate the tumor suppressor protein in normal cells and induce cell proliferation activity to identify early phase markers of cancer.