Nanoplex delivery of siRNA and prodrug enzyme for multimodality image-guided molecular pathway targeted cancer therapy

Cong Li, Marie France Penet, Flonné Wildes, Tomoyo Takagi, Zhihang Chen, Paul T. Winnard, Dmitri Artemov, Zaver M. Bhujwalla

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The ability to destroy cancer cells while sparing normal tissue is highly sought after in cancer therapy. Small interfering RNA (siRNA)-mediated silencing of cancer-cell-specific targets and the use of a prodrug enzyme delivered to the tumor to convert a nontoxic prodrug to an active drug are two promising approaches in achieving this goal. Combining both approaches into a single treatment strategy can amplify selective targeting of cancer cells while sparing normal tissue. Noninvasive imaging can assist in optimizing such a strategy by determining effective tumor delivery of the siRNA and prodrug enzyme to time prodrug administration and detecting target down-regulation by siRNA and prodrug conversion by the enzyme. In proof-of-principle studies, we synthesized a nanoplex carrying magnetic resonance imaging (MRI) reporters for in vivo detection and optical reporters for microscopy to image the delivery of siRNA and a functional prodrug enzyme in breast tumors and achieve image-guided molecular targeted cancer therapy. siRNA targeting of choline kinase-α (Chk-α), an enzyme significantly up-regulated in aggressive breast cancer cells, was combined with the prodrug enzyme bacterial cytosine deaminase (bCD) that converts the nontoxic prodrug 5-fluorocytosine (5-FC) to cytotoxic 5-fluorouracil (5-FU). In vivo MRI and optical imaging showed efficient intratumoral nanoplex delivery. siRNA-mediated down-regulation of Chk-α and the conversion of 5-FC to 5-FU by bCD were detected noninvasively with 1H MR spectroscopic imaging and 19F MR spectroscopy. Combined siRNA and prodrug enzyme activated treatment achieved higher growth delay than either treatment alone. The strategy can be expanded to target multiple pathways with siRNA.

Original languageEnglish (US)
Pages (from-to)6707-6716
Number of pages10
JournalACS Nano
Issue number11
StatePublished - Nov 23 2010


  • Cancer
  • Image-guided siRNA delivery
  • Molecular imaging
  • Prodrug enzyme therapy

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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