Targeting KRAS and MYC has been a tremendous challenge in cancer drug development. Genetic studies in mouse models have validated the efficacy of silencing expression of both KRAS and MYC in mutant KRAS driven tumors. We investigated the therapeutic potential of a new oligonucleotide-mediated gene silencing technology (U1 Adaptor) targeting KRAS and MYC in pancreatic cancer. Nanoparticles in complex with anti-KRAS U1 Adaptors (U1-KRAS) showed remarkable inhibition of KRAS in different human pancreatic cancer cell lines in vitro and in vivo. As a nanoparticle-free approach is far easier to develop into a drug, we refined the formulation of U1 Adaptors by conjugating them to tumor targeting peptides (iRGD and cRGD). Peptides coupled to fluorescently tagged U1 Adaptors showed selective tumor localization in vivo. Efficacy experiments in pancreatic cancer xenograft models showed highly potent (>90%) anti-tumor activity of both iRGD and (cRGD)2-KRAS Adaptors. U1 Adaptors targeting MYC inhibited pancreatic cancer cell proliferation caused apoptosis in vitro (40-70%) and tumor regressions in vivo. Comparison of iRGD conjugated U1 KRAS and U1 MYC Adaptors in vivo revealed a significantly greater degree of cleaved caspase-3 staining and decreased Ki67 staining as compared with controls. There was no significant difference in efficacy between the U1 KRAS and U1 MYC Adaptor groups. Our results validate the value in targeting both KRAS and MYC in pancreatic cancer therapeutics and provide evidence that the U1 Adaptor technology can be successfully translated using a nanoparticle free delivery system to target two undruggable genes in cancer.
- Received December 15, 2016.
- Revision received March 27, 2017.
- Accepted March 27, 2017.
- Copyright ©2017, American Association for Cancer Research.