Folate receptor-targeted nanoparticle delivery of HuR-RNAi suppresses lung cancer cell proliferation and migration

Abstract

BackgroundHuman antigen R (HuR) is an RNA binding protein that is overexpressed in many human cancers, including lung cancer, and has been shown to regulate the expression of several oncoproteins. Further, HuR overexpression in cancer cells has been associated with poor-prognosis and therapy resistance. Therefore, we hypothesized that targeted inhibition of HuR in cancer cells should suppress several HuR-regulated oncoproteins resulting in an effective anticancer efficacy. To test our hypothesis, in the present study we investigated the efficacy of folate receptor-α (FRA)-targeted DOTAP:Cholesterol lipid nanoparticles carrying HuR siRNA (HuR-FNP) against human lung cancer cells.ResultsThe therapeutic efficacy of HuR-FNP was tested in FRA overexpressing human H1299 lung cancer cell line and compared to normal lung fibroblast (CCD16) cells that had low to no FRA expression. Physico-chemical characterization studies showed HuR-FNP particle size was 303.3 nm in diameter and had a positive surface charge (+4.3 mV). Gel retardation and serum stability assays showed that the FNPs were efficiently protected siRNA from rapid degradation. FNP uptake was significantly higher in H1299 cells compared to CCD16 cells indicating a receptor-dose effect. The results of competitive inhibition studies in H1299 cells demonstrated that HuR-FNPs were efficiently internalized via FRA-mediated endocytosis. Biologic studies demonstrated HuR-FNP but not C-FNP (control siRNA) induced G1 phase cell-cycle arrest and apoptosis in H1299 cells resulting in significant growth inhibition. Further, HuR-FNP exhibited significantly higher cytotoxicity against H1299 cells than it did against CCD16 cells. The reduction in H1299 cell viability was correlated with a marked decrease in HuR mRNA and protein expression. Further, reduced expression of HuR-regulated oncoproteins (cyclin D1, cyclin E, and Bcl-2) and increased p27 tumor suppressor protein were observed in HuR-FNP-treated H1299 cells but not in C-FNP-treated cells. Finally, cell migration was significantly inhibited in HuR-FNP-treated H1299 cells compared to C-FNP.ConclusionsOur results demonstrate that HuR is a molecular target for lung cancer therapy and its suppression using HuR-FNP produced significant therapeutic efficacy in vitro.

Spermidine-mediated poly(lactic-<em>co</em>-glycolic acid)&nbsp;nanoparticles containing fluorofenidone for the treatment of idiopathic pulmonary fibrosis

“…Biocompatible and biodegradable polymers, such as PLGA and PEG, are frequently used to encapsulate a variety of therapeutic compounds, drugs, siRNA, DNA, and molecular/dye probes inside the matrix shield. 24,45,72 PLGA and PEG have many unique functional features, not only encapsulating hydrophilic and hydrophobic drugs but also allowing therapeutic targeting. We have previously described in detail the application of PLGA microspheres for controlled and sustained drug delivery of AKF to control PQ-induced inflammation in Sprague Dawley rat lungs, though these microspheres failed to address active targeting of type II pneumocytes and relied on particle size for lung targeting.…”

“…At present, lung-targeted drug-delivery systems include microparticles 23,24 (microspheres and microcapsules) and liposomes, 25,26 and intravenous injection and pulmonary inhalation are the main administration routes. 27 Encapsulating antifibrotic drugs within biodegradable polymers to form microspherical particles has been reported in a lung-targeting drug-delivery system.…”

“…25 Enhancement of drug accumulation in lung tissue by active targeting could improve local therapeutic efficacy and reduce systemic adverse reactions. 24,[33][34][35] Among the various kinds of polymer-based NPs, poly(lactic-co-glycolic acid) (PLGA)-based formulations are considered ideal and safe vehicles for different drugs. 36,37 In this regard, NPs based on amphiphilic copolymers of polyethylene glycol (PEG; as a hydrophilic) and PLGA have already been approved by the US Food and Drug Administration (FDA), and PEG-PLGA copolymers are safe and nontoxic after hydrolysis in vivo.…”

Nanoparticles for siRNA-Based Gene Silencing in Tumor Therapy

“…It has been demonstrated that targeting enhances the circulation time and cellular uptake, decreases systemic toxicity, and delivers the nucleic acid therapeutics effectively [56]. The targeting moieties include receptor substrates, cell-penetrating peptides, and monoclonal antibodies.…”

“…Previous studies from our laboratory showed that DOTAP:chol can efficiently deliver DNA and siRNA both in vitro and in vivo . DOTAP:chol liposomes were modified with folic acid molecules (FNP) for targeted siRNA delivery in folate receptor-overexpressing lung cancer cells [56]. FNP was used to encapsulate siRNA molecules specific for RNA binding protein HuR (HuR-FNP) in cancer cells.…”