EpCAM aptamer mediated cancer cell specific delivery of EpCAM siRNA using polymeric nanocomplex

Abstract

BackgroundEpithelial cell adhesion molecule (EpCAM) is overexpressed in solid tumors and regarded as a putative cancer stem cell marker. Here, we report that employing EpCAM aptamer (EpApt) and EpCAM siRNA (SiEp) dual approach, for the targeted delivery of siRNA to EpCAM positive cancer cells, efficiently inhibits cancer cell proliferation.ResultsTargeted delivery of siRNA using polyethyleneimine is one of the efficient methods for gene delivery, and thus, we developed a novel aptamer-PEI-siRNA nanocomplex for EpCAM targeting. PEI nanocomplex synthesized with EpCAM aptamer (EpApt) and EpCAM siRNA (SiEp) showed 198 nm diameter sized particles by dynamic light scattering, spherical shaped particles, of 151 ± 11 nm size by TEM. The surface charge of the nanoparticles was −30.0 mV using zeta potential measurements. Gel retardation assay confirmed the PEI-EpApt-SiEp nanoparticles formation. The difference in size observed by DLS and TEM could be due to coating of aptamer and siRNA on PEI nanocore. Flow cytometry analysis revealed that PEI-EpApt-SiEp has superior binding to cancer cells compared to EpApt or scramble aptamer (ScrApt) or PEI-ScrApt-SiEp. PEI-EpApt-SiEp downregulated EpCAM and inhibited selectively the cell proliferation of MCF-7 and WERI-Rb1 cells.ConclusionsThe PEI nanocomplex fabricated with EpApt and siEp was able to target EpCAM tumor cells, deliver the siRNA and silence the target gene. This nanocomplex exhibited decreased cell proliferation than the scrambled aptamer loaded nanocomplex in the EpCAM expressing cancer cells and may have potential for EpCAM targeting in vivo.Electronic supplementary materialThe online version of this article (doi:10.1186/s12929-014-0108-9) contains supplementary material, which is available to authorized users.

Nanoparticles for siRNA-Based Gene Silencing in Tumor Therapy

“…Subramanian et al . reported that, by conjugating epithelial cell adhesion molecule (EpCAM) aptamer to PEI-siEp (siRNA) complex, specific silencing of EpCAM was achieved and cancer cell proliferation was selectively inhibited [71]. Another study also reported VEGF-targeted siRNA delivery by synthesizing bioreducible PEI (SS-PEI) polymer for treating liver cancer in vivo .…”

Cell-targeting aptamers act as intracellular delivery vehicles

“…In this regard, several shortened aptamers have been proposed with different analytes (Gopinath et al 2006a), as smaller aptamers perform better as chimeras because longer aptamers may undergo degradation. In recent years, there has been an increasing interest in the applications of aptamer chimeras in the field of therapeutics Rohde et al 2015;Subramanian et al 2015;Wang et al 2015;Diao et al 2016). Rohde et al (2015) demonstrated a transferrin receptor and microRNA aptamer chimera (mir-126) that promoted sprouting of endothelial cells and suppressed recruitment of breast cancer cells.…”

“…Rohde et al (2015) demonstrated a transferrin receptor and microRNA aptamer chimera (mir-126) that promoted sprouting of endothelial cells and suppressed recruitment of breast cancer cells. An aptamersiRNA polymeric nanocomplex was designed for targeting epithelial cell adhesion molecules, which are overexpressed in solid tumors (Subramanian et al 2015), and Wang et al (2015) used the aptamer-siRNA chimera to silence survivin in cancer cells and enhance the effect of doxorubicin, even when used in small amounts. Very recently, using an antiprostate specific membrane antigen aptamer-siRNA chimera, Diao et al (2016) specifically controlled the growth of a prostate tumor.…”

Aptamer-Mediated Targeted Delivery of Therapeutics: An Update

“…Cellular uptake of the complex was evaluated in vitro by flow cytometry and fluorescent microscopy. Inhibition of cancer cell proliferation was evaluated by an MTT assay [110]. …”