Nanoparticles for targeted delivery of therapeutics and small interfering RNAs in hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) is the 5(th) most common malignancy which is responsible for more than half million annual mortalities; also, it is the third leading cause of cancer related death. Unfavorable systemic side-effects of chemotherapeutic agents and susceptibility to the degradation of small interfering RNAs (siRNAs), which can knock down a specific gene involved in the disease, have hampered their clinical application. So, it could be beneficial to develop an efficient carrier for the stabilization and specific delivery of drugs and siRNA to cells. Targeted nanoparticles have gained considerable attention as an efficient drug and gene delivery system, which is due to their capability in achieving the highest accumulation of cytotoxic agents in tumor tissue, modifiable drug pharmacokinetic- and bio-distribution, improved effectiveness of treatment, and limited side-effects. Recent studies have shed more light on the advantages of novel drug loaded carrier systems vs free drugs. Most of the animal studies have reported improvement in treatment efficacy and survival rate using novel carrier systems. Targeted delivery may be achieved passively or actively. In passive targeting, no ligand as homing device is used, while targeting is achieved by incorporating the therapeutic agent into a macromolecule or nanoparticle that passively reaches the target organ. However, in active targeting, the therapeutic agent or carrier system is conjugated to a tissue or cell-specific receptor which is over-expressed in a special malignancy using a ligand called a homing device. This review covers a broad spectrum of targeted nanoparticles as therapeutic and non-viral siRNA delivery systems, which are developed for enhanced cellular uptake and targeted gene silencing in vitro and in vivo and their characteristics and opportunities for the clinical applications of drugs and therapeutic siRNA are discussed in this article. Asialoglycoprotein receptors, low-density lipoprotein, ganglioside GM1 cell surface ligand, epidermal growth factor receptor receptors, monoclonal antibodies, retinoic acid receptors, integrin receptors targeted by Arg-Gly-Asp peptide, folate, and transferrin receptors are the most widely studied cell surface receptors which are used for the site specific delivery of drugs and siRNA-based therapeutics in HCC and discussed in detail in this article.

Keywords: Chemotherapeutic agents; Hepatocellular carcinoma; Nanoparticle; Small interfering RNA; Targeted delivery.

Figure 1

Schematic representation of various treatment strategies for hepatocellular carcinoma at different stages according to the Barcelona Clinic Liver Cancer algorithm. RFA: Radiofrequency ablation, PEI: Percutaneous ethanol injection; TACE: Trans catheter arterial chemoembolization.

Figure 2

Different methods of targeted delivery of nanoparticles by passive or active mechanism. EPR: Enhanced permeation and retention.

Figure 3

Schematic representation of the biotinylated cyclic Arg-Gly-Asp nanoparticles loaded with doxorubicin. PEG: Polyethylene glycol; RGD: Arg-Gly-Asp.