Intracellular gold nanoparticles enhance non-invasive radiofrequency thermal destruction of human gastrointestinal cancer cells

Christopher J Gannon,Resham Bhattacharya,Priyabrata Mukherjee,Chitta Ranjan Patra,Steven A Curley

doi:10.1186/1477-3155-6-2

Abstract

BackgroundNovel approaches to treat human cancer that are effective with minimal toxicity profiles are needed. We evaluated gold nanoparticles (GNPs) in human hepatocellular and pancreatic cancer cells to determine: 1) absence of intrinsic cytotoxicity of the GNPs and 2) external radiofrequency (RF) field-induced heating of intracellular GNPs to produce thermal destruction of malignant cells. GNPs (5 nm diameter) were added to 2 human cancer cell lines (Panc-1, Hep3B). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and propidium iodide-fluorescence associated cell sorting (PI-FACS) assessed cell proliferation and GNP-related cytotoxicity. Other GNP-treated cells were exposed to a 13.56 MHz RF field for 1, 2, or 5 minutes, and then incubated for 24 hours. PI-FACS measured RF-induced cytotoxicity.ResultsGNPs had no impact on cellular proliferation by MTT assay. PI-FACS confirmed that GNPs alone produced no cytotoxicity. A GNP dose-dependent RF-induced cytotoxicity was observed. For Hep3B cells treated with a 67 μM/L dose of GNPs, cytotoxicity at 1, 2 and 5 minutes of RF was 99.0%, 98.5%, and 99.8%. For Panc-1 cells treated at the 67 μM/L dose, cytotoxicity at 1, 2, and 5 minutes of RF was 98.5%, 98.7%, and 96.5%. Lower doses of GNPs were associated with significantly lower rates of RF-induced thermal cytotoxicity for each cell line (P < 0.01). Cells not treated with GNPs but treated with RF for identical time-points had less cytotoxicity (Hep3B: 17.6%, 21%, and 75%; Panc-1: 15.3%, 26.4%, and 39.8%, all P < 0.01).ConclusionWe demonstrate that GNPs 1) have no intrinsic cytotoxicity or anti-proliferative effects in two human cancer cell lines in vitro and 2) GNPs release heat in a focused external RF field. This RF-induced heat release is lethal to cancer cells bearing intracellular GNPs in vitro.

Highlights

Novel approaches to treat human cancer that are effective with minimal toxicity profiles are needed
gold nanoparticles (GNPs) heating Heating of GNPs with the external RF device occurred in a nonlinear fashion (Fig. 1)
Increasing GNP concentration and increasing RF generator power both contributed to increased total heating and rate of heating of water to a boiling point

Summary

Introduction

Novel approaches to treat human cancer that are effective with minimal toxicity profiles are needed. Non-invasive RF treatment of malignant tumors at any site in the body should be possible, but such a treatment would require the presence of intracellular or intratumoral agents that release heat under the influence of the RF field. For such a novel RF treatment approach to be effective, it will require identification of agents that have little or no intrinsic cellular or tissue toxicity that can be targeted or directed to malignant cells while sparing normal cells. A non-invasive approach with the potential to treat many types of cancers effectively with minimal or no toxic effects to normal cells would be highly beneficial

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