Systematic Evaluation of Biophysical and Functional Characteristics of Selenomethylene-Locked Nucleic Acid-Mediated Inhibition of miR-21

Biochemistry. 2016 Dec 20;55(50):7023-7032. doi: 10.1021/acs.biochem.6b00895. Epub 2016 Dec 5.

Abstract

miRNAs constitute an important layer of gene regulation mediated by sequence-specific targeting of mRNAs. Aberrant expression of miRNAs contributes to a host of pathological states. Promoting cancer, miR-21 is upregulated in variety of cancers and promotes tumor progresion by suppressing a network of tumor suppressor genes. Here we describe a novel class of bicyclic RNA analogues, selenomethylene-locked nucleic acid (SeLNA), that display high affinity, improved metabolic stability, and increased potency for miR-21 inhibition. The thermal stability (Tm) for duplexes was increased significantly with incorporation of SeLNA monomers as compared to that of the unmodified DNA-RNA hybrid. A comprehensive thermodynamic profile obtained by isothermal titration calorimetry revealed a favorable increase in the enthalpy of hybridization for SeLNA containing DNA and target RNA heteroduplexes. SeLNA modifications displayed remarkable binding affinity for miR-21 target RNA with a Ka of ≤1.05 × 108 M-1. We also observed enhanced serum stability for SeLNA-RNA duplexes with a half-life of ≤36 h. These in vitro results were well correlated with the antisense activity in cancer cells imparting up to ∼91% inhibition of miR-21. The functional impact of SeLNA modifications on miR-21 inhibition was further gauged by investigating the migration and invasion characterisitics of cancer cells, which were drastically reduced to ∼49 and ∼55%, respectively, with SeLNA having four such modifications. Our findings demonstrate SeLNA as a promising candidate for therapeutics for disease-associated miRNAs.

Publication types

  • Evaluation Study

MeSH terms

  • Apoptosis
  • Blotting, Western
  • Cell Movement*
  • Cell Proliferation*
  • Circular Dichroism
  • Humans
  • Luciferases / metabolism
  • MCF-7 Cells
  • MicroRNAs / antagonists & inhibitors*
  • MicroRNAs / genetics
  • Oligonucleotides / administration & dosage
  • Oligonucleotides / chemistry*
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Selenium / chemistry*

Substances

  • MIRN21 microRNA, human
  • MicroRNAs
  • Oligonucleotides
  • RNA, Messenger
  • locked nucleic acid
  • Luciferases
  • Selenium