Engineered fusion protein-loaded gold nanocarriers for targeted co-delivery of doxorubicin and erbB2-siRNA in human epidermal growth factor receptor-2+ ovarian cancerElectronic supplementary information (ESI) available. See DOI: 10.1039/c7tb01587a

Designed recombinant proteins comprising functional domains offer selective targeting of cancer cells for the efficient delivery of therapeutic agents. The efficacy of these carriers can be further enhanced by conjugating engineered proteins to nanoparticle surfaces. However, recombinant protein-loaded nanoparticle-based drug delivery systems are not well addressed for ovarian cancer therapy. In the present study, using a combinatorial approach, we designed and fabricated a drug delivery system by combining gold nanoparticles (AuNPs) with an engineered bi-functional recombinant fusion protein TRAF(C) (TR), loaded with an anticancer drug, namely doxorubicin (DX), and erbB2-siRNA (si), to mediate target specific delivery into SK-OV-3, a model human ovarian cancer cell line over expressing HER2 receptors ( i.e. human epidermal growth factor receptor-2). The nanoparticle-based targeted drug delivery system, designated as TDDS (Au-TR-DX-si), was found to be stable and homogenous as revealed by physicochemical and biochemical studies in vitro . In addition, TDDS was functional upon evaluation in vivo . Intraperitoneal administration of TDDS at 2.5 mg kg −1 of DX and 0.25 mg kg −1 of erbB2 siRNA into SK-OV-3 xenograft nude mice, revealed target specific uptake and consequent gene silencing resulting in significant tumor suppression. We attribute these results to specific co-delivery of erbB2 siRNA and DX mediated by TDDS into SK-OV-3 cells via HER2 receptors. Additionally, the biodistribution of TDDS, as quantitated by ICP-OES, confirmed tumor-specific accumulation of AuNPs primarily in tumor tissues, which firmly establishes the efficacy of the nanomedicine-based combinatorial approach for the treatment of ovarian cancer in a non-toxic manner. Based on these findings, we strongly believe that the nanomedicine-based combinatorial approach can be developed as a universal strategy for treatment of HER2+ ovarian cancers. Gold nanoparticle based targeted drug delivery system (TDDS) for transporting DX and siRNA in HER2+ ovarian cancer.