Silencing of skeletal metastasis-associated genes impairs migration of breast cancer cells and reduces osteolytic bone lesions

Christina Reufsteck, Rinat Lifshitz-Shovali, Michael Zepp, Tobias Bäuerle, Dieter Kübler, Gershon Golomb, Martin R. Berger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Bone sialoprotein (BSP) and osteopontin (OPN) are important factors in the metastasis of breast cancer, which were examined as targets for antineoplastic therapy by siRNA. In addition, the effect of gene silencing on their transcription factor Runx2 and their interaction partners integrin b3 and matrix metalloproteinase 2 was studied. The effect of siRNAs directed against these genes was assessed by monitoring expression levels followed by functional assays in cell culture as well as skeletal metastases caused by human MDA-MB-231luc breast cancer cells in nude rats. Upon silencing of the targets, cell migration was profoundly impaired (p\0.001 for BSP-siRNA), but the impact on proliferation was low. Systemic administration by osmotic mini-pumps of BSP-siRNA but not OPN-siRNA decreased osteolytic lesions (p = 0.067). Extraosseous tumour growth was not affected. As an alternative approach, non-viral, polymeric based formulations of siRNAs in nanoparticles (NP) were developed. Locoregional administration of the two siRNAs targeting OPN and BSP encapsulated in these biodegradable NP reduced skeletal lesions even more efficiently (p = 0.03). Compared to systemic administration, this treatment caused not only a more pronounced antiosteolytic effect at a 25-fold lower total siRNA dose, but also had a slight reducing effect on tumour incidence (p = 0.095). In conclusion, the siRNA treatment had a small effect on cellular proliferation but a significant efficacy against migration of and osteolysis induced by MDAMB-231 cells. Our data underline that siRNA mediated knockdown is a powerful tool for identifying targets for pharmacological intervention. In addition, encapsulation of siRNA into biodegradable NP is a strategy, which promises well for using siRNA.

Original languageEnglish
Pages (from-to)441-456
Number of pages16
JournalClinical and Experimental Metastasis
Volume29
Issue number5
DOIs
StatePublished - Jun 2012

Keywords

  • Bone sialoprotein
  • Breast cancer bone metastasis
  • Nanoparticles
  • Osteolysis
  • Osteopontin
  • SiRNA

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