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HER2 Targeted Breast Cancer Therapy with Switchable “Off/On” Multifunctional “Smart” Magnetic Polymer Core−Shell Nanocomposites Raju Vivek,*,†,∇,# Ramar Thangam,†,§,# Selvaraj Rajesh Kumar,‡ Chandrababu Rejeeth,†,∇ Srinivasan Sivasubramanian,§ Savariar Vincent,⊥ Dhanaraj Gopi,⊗ and Soundarapandian Kannan*,∥ †
Proteomics & Molecular Cell Physiology Laboratory, Department of Zoology, Bharathiar University, Coimbatore 641 046, Tamil Nadu, India § King Institute of Preventive Medicine & Research, Guindy, Chennai 600 032, Tamil Nadu, India ‡ Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046, Tamil Nadu, India ⊥ Loyola Institute of Frontier Energy (LIFE), Loyola College, Chennai 600 034 Tamil Nadu, India ∥ Department of Zoology, ⊗Department of Chemistry, Periyar University, Salem 636 011, Tamil Nadu, India S Supporting Information *
ABSTRACT: Multifunctional magnetic polymer nanocombinations are gaining importance in cancer nanotheranostics due to their safety and their potential in delivering targeted functions. Herein, we report a novel multifunctional core−shell magnetic polymer therapeutic nanocomposites (NCs) exhibiting pH dependent “Off−On” release of drug against breast cancer cells. The NCs are intact in blood circulation (“Off” state), i.e., at physiological pH, whereas activated (“On” state) at intracellular acidic pH environment of the targeted breast cancer cells. The NCs are prepared by coating the cannonball (iron nanocore) with hydrophobic nanopockets of pH-responsive poly(D,L-lactic-co-glycolic acid) (PLGA) polymer nanoshell that allows efficient loading of therapeutics. Further, the nanocore−polymer shell is stabilized by poly(vinylpyrrolidone) (PVP) and functionalized with a targeting HER2 ligand. The prepared Her−Fe3O4@PLGA−PVP nanocomposites facilitate packing of anticancer drug (Tamoxifen) without premature release in the bloodstream, recognizing the target cells through binding of Herceptin antibody to HER2, a cell surface receptor expressed by breast cancer cells to promote HER2 receptor mediated endocytosis and finally releasing the drug at the intracellular site of tumor cells (“On” state) to induce apoptosis. The therapeutic efficiency of hemo/cytocompatible NCs drug delivery system (DDS) in terms of targeted delivery and sustained release of therapeutic agent against breast cancer cells was substantiated by in vitro and in vivo studies. The multifunctional properties of Her−Tam−Fe3O4@PLGA−PVP NCs may open up new avenues in cancer therapy through overcoming the limitations of conventional cancer therapy. KEYWORDS: HER2 receptor, breast cancer, iron oxide, poly(D,L-lactic-co-glycolic acid), magnetic PLGA, pH-responsiveness, targeted cancer therapy
1. INTRODUCTION Nanotechnology has spanned the potential to provide solutions for longstanding conundrums such as biomarkers discovery, molecular diagnosis and targeted drug delivery through the design of “smart” nanostructures that integrate multiple functions. Recently, magnetic nanoparticles (MNPs) have been extensively studied for their potential applications in the development of biosensors,1 data-storage devices,2 magnetically targeted DDS,3,4 contrast agents,5,6 and magnetic inks for jet printing.7 The magnetic core of the MNPs is composed of biocompatible magnetite (Fe3O4) or maghemite (γ-Fe3O4) that facilitates substantial accumulation of MNPs at the diseased site through stimuli.5,6,8−10 Despite their promise, MNPs have © XXXX American Chemical Society
limitations such as their reactivity with blood, aggregation at physiological blood pH and the degradation of MNPs into free ions in a physiological environment leading to generation of free radicals in cells thereby causing apoptosis.11 To circumvent the problems of MNPs in clinical applications, new biocompatible nanomaterials are designed by combining metal or inorganic and organic (polymer) components that provide improved blood circulation lifetimes due to colloidal stability of these materials.8 Responsive polymers are frequently Received: November 17, 2015 Accepted: January 5, 2016
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DOI: 10.1021/acsami.5b11103 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
Research Article
ACS Applied Materials & Interfaces
Scheme 1. Schematic Description of the Developed Strategy of Programmable Transition From “Off” State to “On” State Core− Shell NCs Triggered in Response to the Low pH in Tumorsa
The NCs remain in “Off” (nonfluorescent) state during their circulation in blood (pH 7.4). After reaching the target tumor cells, binding of Herceptin of NCs with HER2 membrane receptors of tumor cells, internalization of NCs by endocytosis, and incorporation into the accumulated cytoplasmic early endosomes progressing to late endo/lysosome (pH 5.0), where the acidic pH activates the NCs to “On” state, making highly fluorescent. In the “On” state, the rapid degradation of NCs resulted in complete release of drugs as well as reduction of the expression of HER2 surface proteins to stop the proliferation signals. The released Tam generates ROS by causing mitochondrial membrane potential loss (ΔΨm), leading to release of cytochrome c into the cytosol for activation of effector caspases to induce cancer cell apoptosis. a
hyperthermia effect in the presence of an alternating magnetic field.5,6,10−12 Polymer coated MNPs can be easily tailored by the incorporation of targeting moieties, fluorescence dyes, or therapeutic agents.8,12−15 Lin et al.16 have reported the fabrication of a polymeric shell around the MNPs core that enabled intracellular mRNA detection and imaging of photothermal therapy. Despite the recent progress in the fabrication of multifunctional MNPs against cancer cells, challenges on maintaining the structural integrity of these nanodrug carriers without any risk of degradation or premature drug release in blood circulation, inefficient targetability and difficulty in the control over of the drug release after reaching the target site of action still exist.20,21 This can be accomplished by keeping the nanostructures intact at physiological pH (“Off” state in circulation) and the release of drugs from NCs in the cancer cells at acidic pH (“On” state at the site of action). This pH based “Off” and “On” states of nanostructures not only show unique ability to control drug release at the specified site of action but also minimize the drug dose unlike conventional monotherapy. Breast cancer represents a significant global health problem with increasing incidence and mortality rates. Various chemotherapeutic agents are used to treat the disease with the aforementioned limitations. Besides, antibodies such as Herceptin have also been used either alone or in combination with anticancer drug to treat cancer through targeting human epidermal growth factor receptor-2 (HER2) because the breast
used in combinations with Fe3O4 magnetic cannonballs due to their desirable biocompatible and biodegradable properties.3,4,12 Among the popular responsive polymers, biodegradable aliphatic poly(D,L-lactic-co-glycolic acid) (PLGA) polyester offers attractive properties such as nonantigenicity, nontoxicity and biocompatibility useful in the development of functional nanodevices for controlled delivery of drugs, proteins, DNA, RNA, peptides, and scaffolds for tissue engineering applications.8,13 Until recently, chemotherapy is the predominant treatment strategy recommended against several cancers with demerits such as multidrug resistance (MDR), the requirement of high drug dose and nonspecific toxicity to healthy cells as well as tissues.13 Several multifunctional nanostrategies including MNPs are developed not only to overcome the limitations of chemotherapy but also to improve the functions such as selective targeting of cancer cells and internalization, drug release and subsequent induction of apoptosis.8,12,16−20,53 Nanotheranostic probes that codeliver the functions of realtime monitoring and therapeutic action in addition to the above desirable functions are reported.19,53 Multifunctional MNPs loaded with anticancer drugs are used as theranostic agents against cancer cells due to their potential in exhibiting the superparamagnetic property, a feature used to diagnose the cancer cells as well as real-time monitoring of therapeutics by magnetic resonance imaging (MRI) upon delivery of these materials into the cells. They also contribute to the localized B
DOI: 10.1021/acsami.5b11103 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
Research Article
ACS Applied Materials & Interfaces
for further PLGA nanoshell coating; however, APTS could limit the particle growth size to
