A short hairpin DNA analogous to miR-125b inhibits C-Raf expression, proliferation, and survival of breast cancer cells

Mol Cancer Res. 2009 Oct;7(10):1635-44. doi: 10.1158/1541-7786.MCR-09-0043. Epub 2009 Oct 13.

Abstract

The noncoding RNA miR-125b has been described to reduce ErbB2 protein expression as well as proliferation and migration of cancer cell lines. As additional target of miR-125b, we identified the c-raf-1 mRNA by sequence analysis. We designed a short hairpin-looped oligodeoxynucleotide (ODN) targeted to the same 3' untranslated region of c-raf-1 mRNA as miR-125b. The fully complementary ODN antisense strand is linked to a second strand constituting a partially double-stranded structure of the ODN. Transfection of the c-raf-1-specific ODN (ODN-Raf) in a breast cancer cell line reduced the protein levels of C-Raf, ErbB2, and their downstream effector cyclin D1 similar to miR-125b. MiR-125b as well as ODN-Raf showed no effect on the c-raf-1 mRNA level in contrast to small interfering RNA. Unlike miR-125b, ODN-Raf induced a cytopathic effect. This may be explained by the structural properties of ODN-Raf, which can form G-tetrads. Thus, the short hairpin-looped ODN-Raf, targeting the same region of c-raf-1 as miR-125b, is a multifunctional molecule reducing the expression of oncoproteins and stimulating cell death. Both features may be useful to interfere with tumor growth.

MeSH terms

  • Breast Neoplasms / genetics*
  • Breast Neoplasms / physiopathology
  • Breast Neoplasms / therapy
  • Carcinoma / genetics*
  • Carcinoma / physiopathology
  • Carcinoma / therapy
  • Cell Death / genetics
  • Cell Line, Tumor
  • Cell Proliferation
  • Cell Survival / genetics
  • Down-Regulation / genetics
  • Female
  • Gene Expression Regulation, Neoplastic / genetics
  • Genetic Therapy / methods
  • Humans
  • Inverted Repeat Sequences / genetics
  • MicroRNAs / genetics*
  • Oligodeoxyribonucleotides, Antisense / chemical synthesis
  • Oligodeoxyribonucleotides, Antisense / genetics*
  • Proto-Oncogene Proteins c-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-raf / genetics
  • Proto-Oncogene Proteins c-raf / metabolism
  • RNA, Messenger / metabolism
  • Receptor, ErbB-2 / genetics
  • Transfection / methods*

Substances

  • MIRN125 microRNA, human
  • MicroRNAs
  • Oligodeoxyribonucleotides, Antisense
  • RNA, Messenger
  • ERBB2 protein, human
  • Receptor, ErbB-2
  • Proto-Oncogene Proteins c-raf