Gold nanocages (AuNCs) have been shown to be a useful tool both for imaging and hyperthermia therapy of cancer, thanks to their outstanding optical properties, low toxicity and facile functionalization with targeting molecules, including peptides and antibodies. Here, we use AuNCs for selective targeting of prostate cancer cells via specific interaction between neuropeptide Y (NPY) receptor and peptides conjugated to the AuNCs surface. Three different peptides derived from NPY have been synthesized ad hoc and covalently conjugated to AuNCs, giving stable nanoconjugates. UV-vis band of the nanoconjugates was set around 800 nm for subsequent hyperthermia experiments, which is particularly promising for next preclinical investigations. Long-term stability of nanoconjugates in different media has been confirmed both by UV-vis and DLS studies. Active NPY receptor targeting was observed by confocal microscopy showing large time-dependent AuNCs cellular uptake. Activation of ERK1/2 pathway has been evaluated by Western blot analysis to confirm specific interaction. Moreover, cellular uptake kinetics were compared as a function of peptide structure. Cytotoxicity of nanoconjugates has been evaluated by MTS and Annexin V assays, confirming their safety within the concentration range explored. Hyperthermia studies were carried out irradiating the cells, previously incubated with AuNCs, with a pulsed laser at 808 nm wavelength. Different laser power densities and irradiation times were used and the cellular viability was compared using both MTS assay and confocal microscopy. In particular, calcein AM/propidium iodide assay showed the presence of dead cells after 10 min irradiation at relatively low power density of 2.6 W/cm2. Caspase-3 and Annexin V assays has been used in order to understand the cell death mechanism by apoptosis or necrosis. Moreover, ATP levels as indicator of cell viability was measured by ATP-bioluminescence assay. In summary, our peptide-NC conjugates proved to be an efficient theranostic nanosystem for targeted detection and activatable killing of prostate cancer cells.

Gold nanocages for imaging and therapy of prostate cancer by active targeting of neuropeptide Y-receptor

251st National Meeting (2016)

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