Delivery of CD44 shRNA/nanoparticles within cancer cells: perturbation of hyaluronan/CD44v6 interactions and reduction in adenoma growth in Apc Min/+ MICE.

Our studies have shown that constitutive interactions between hyaluronan and CD44 on tumor cells induces various anti-apoptotic cell survival pathways through the formation of a multimeric signaling complex that contains activated receptor tyrosine kinases. Inhibition of the hyaluronan-CD44 interactions on tumor cells by hyaluronan-CD44 interaction antagonists suppresses these activities by disassembling the complex. Although the anti-tumor activity of hyaluronan-oligosaccharides, a hyaluronan-CD44 interaction antagonist, is effective in sensitizing tumor cells to chemotherapeutic agents and reducing tumor growth in xenografts, hyaluronan-oligosaccharide alone was not effective in reducing tumor progression in Apc Min/+ mice. We now show in vitro and in vivo that targeted inhibition of the expression of CD44v6 depletes the ability of the colon tumor cells to signal through hyaluronan-CD44v6 interactions. First, we cloned oligonucleotides coding CD44v6 shRNA into a conditionally silenced pSico vector. Second, using pSico-CD44v6 shRNA and a colon-specific Fabpl promoter-driven Cre recombinase expression vector packaged into transferrin-coated nanoparticles, we successfully delivered the CD44v6 shRNA within pre-neoplastic and neoplastic colon malignant cells. Third, using the Apc Min/+ mice model, we demonstrated that inhibition of the CD44v6 expression reduces the signaling through a hyaluronan/CD44v6-pErbB2-Cox-2 interaction pathway and reduced adenoma number and growth. Together, these data provide insight into the novel therapeutic strategies of short hairpin RNA/nanoparticle technology and its potential for silencing genes associated with colon tumor cells.