Nano-based hyperthermia for melanoma and breast cancer treatment

Over the past few decades, hyperthermia therapy (HT) has evolved as one of the most promising cancer-treatment approaches. To overcome drawbacks such as non-selectivity and invasiveness, and to improve therapeutic efficacy, HT has been combined with nanotechnology. Gold nanoparticles (AuNPs) and superparamagnetic iron oxide (Fe3O4 MNP) are typically utilized as plasmonic or magnetic hyperthermia agents, since they are able to be rapidly heated upon exposure to bright light source with a precise wavelength or to an alternating current magnetic field (AMF). The raising of the temperature causes apoptosis of tumor cells that are more sensitive to thermal damage than healthy cells. Moreover, is well known that hyperthermia reduces radioresistance and improves the efficacy of anticancer drugs. Herein, we investigate the therapeutic applications of nano-based hyperthermia for melanoma and breast cancer treatment. In particular in the first part of the current work we propose the use of tumor tropic cells, called Endothelial Colony Forming Cells (ECFCs) as cellular carrier of chitosan-coated AuNPs. With this Trojan horse strategy, we evaluated the cooperative effect of radiotherapy and plasmonic photothermal therapy on melanoma and breast cancer cell lines. In the second part of this thesis, we reported two studies in collaboration with CNR of Sesto Fiorentino regarding the antitumoral effects of 1) a multifunctional platform consisting in supermagnetic Fe3O4 MNP encapsulated in a dual pH- and temperature responsive poly (N-vinylcaprolactam-co-acrylic acid) copolymer to achieve highly controlled release of doxorubicin for a multimodal cancer treatment combining hyperthermia and chemotherapy and 2) a Au@Fe3O4 core@shell system with a highly uniform unprecedented star-like shell morphology combining plasmonic and magnetic properties. AuNPs uptake was evaluated in melanoma (A375 and A375-M6), breast cancer cell lines (MCF7 and MDA-MB 231) and ECFCs by conventional optical microscope, transmission electronic microscope (TEM), Inductively Coupled Plasma – Atomic Emission Spectrometry (ICP-AES) and Photoacoustic imaging (PA). The PA signal provided from ECFC loaded with AuNPs exhibited a stronger signal enhancement compared to melanoma and breast cancer cells due to the massive amount of gold nanoparticles that ECFCs are able to incorporate. We evaluated the long-term cytostatic/cytoxic effects of combined radiotherapy and nano-mediated hyperthermia on breast cancer and melanoma cell lines using clonogenic assays while the short-term effects were determined evaluating DNA damage by western blot analysis of cleaved PARP and γH2AX and comet assay. Our data show the cooperative effects of the Xray dose (2Gy) with nano-based hyperthermia with significant reduction of colony number compared to the single treatments. In vivo we proved the tumor homing capacity of AuNP-ECFCs in tumor hypoxic areas. Regarding the Fe3O4 MNP loaded with doxorubicin we demonstrated the efficacy of this multi-stimuli-sensitive nanoplatform for the treatment of the melanoma and breast cancer, while the Au@Fe3O4 magnetic-photermal heterostructure loaded breast cancer cell culture suspension at 658 nm confirmed their optical response and their suitability for photothermal therapy. Findings from this research will be of translational relevance with potential health system impact related to improved control of metastatic disease in melanoma and breast cancer. The possibility of obtaining molecular imaging of primary tumors and metastases (diagnosis) and of inhibiting tumor growth and development of metastases (therapy) through different therapeutic strategies will pave the way for new and promising approaches to combat tumor progression.