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Research Article

Herceptin-directed nanoparticles activated by an alternating magnetic field selectively kill HER-2 positive human breast cells in vitro via hyperthermia

, , , , , & show all
Pages 682-697 | Received 23 Mar 2011, Accepted 28 Jul 2011, Published online: 12 Oct 2011
 

Abstract

Purpose: HER-2 is in the EGF tyrosine kinase receptor family, overexpressed by many human cancers and minimally expressed by normal adult tissues. HER-2 expression in human cancers is correlated with reduced survival, increased metastasis, reduced apoptosis and increased proliferation. Herceptin is a humanised mouse antibody that targets and inactivates HER-2. In the present study, Herceptin was used to deliver ferric oxide-enriched nanoparticles to HER-2+ cancer cells. If exposed to alternating magnetic field (AMF), the nanoparticles heat. We tested the ability of AMF-activated Herceptin-directed nanoparticles to selectively kill HER-2+ human cancer cells.

Methods: Herceptin-conjugated nanoparticles were incubated with normal human mammary epithelial cells (HMEC)(HER-2-) or malignant human mammary epithelial cells (SK-BR-3)(HER-2+). Cells were stained to detect Herceptin or iron and the kinetics of binding quantified. Once conditions were optimised for binding, cells were exposed to either antibody-directed or non-antibody-conjugated nanoparticles, washed and sham-treated or exposed to AMF and cell death quantified.

Results: SK-BR-3 cells bound Herceptin-directed nanoparticles in increasing amounts over 3 h but did not retain non-antibody conjugated nanoparticles. HMECs did not retain either nanoparticles. SK-BR-3 cells with bound Herceptin-directed-nanoparticles, exposed to AMF, died by apoptosis, quantifiable by Live/Dead and nuclear morphology assays and released LDH. Sham-treated SK-BR-3 cells with Herceptin-directed nanoparticles, HMECs with either nanoparticles, with or without AMF treatment, exhibited no increase in toxicity above baseline cell death using these three assays.

Conclusions: These studies demonstrate Herceptin-directed nanoparticles can selectively kill HER-2+ cancer cells via hyperthermia after AMF activation.

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