Combined Ferritin Nanocarriers with ICG for Effective Phototherapy Against Breast Cancer

Abstract

Leopoldo Sitia,1,* Paola Saccomandi,2,* Leonardo Bianchi,2 Marta Sevieri,1 Cristina Sottani,3 Raffaele Allevi,1 Elena Grignani,3 Serena Mazzucchelli,1 Fabio Corsi1,4 1Department of Biomedical and Clinical Sciences, Università degli studi di Milano, Milan, Italy; 2Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy; 3Environmental Research Center, Istituti Clinici Scientifici Maugeri IRCCS, Pavia, Italy; 4Istituti Clinici Scientifici Maugeri IRCCS, Pavia, Italy*These authors contributed equally to this workCorrespondence: Serena Mazzucchelli, Department of Biomedical and Clinical Sciences, Università degli studi di Milano, via G.B. Grassi 74, Milan, 20157, Italy, Email [email protected] Fabio Corsi, Istituti Clinici Scientifici Maugeri IRCCS, via S. Maugeri 10, Pavia, 27100, Italy, Email [email protected]: Photodynamic Therapy (PDT) is a promising, minimally invasive treatment for cancer with high immunostimulatory potential, no reported drug resistance, and reduced side effects. Indocyanine Green (ICG) has been used as a photosensitizer (PS) for PDT, although its poor stability and low tumor-target specificity strongly limit its efficacy. To overcome these limitations, ICG can be formulated as a tumor-targeting nanoparticle (NP).Methods: We nanoformulated ICG into recombinant heavy-ferritin nanocages (HFn-ICG). HFn has a specific interaction with transferrin receptor 1 (TfR1), which is overexpressed in most tumors, thus increasing HFn tumor tropism. First, we tested the properties of HFn-ICG as a PS upon irradiation with a continuous-wave diode laser. Then, we evaluated PDT efficacy in two breast cancer (BC) cell lines with different TfR1 expression levels. Finally, we measured the levels of intracellular endogenous heavy ferritin (H-Fn) after PDT treatment. In fact, it is known that cells undergoing ROS-induced autophagy, as in PDT, tend to increase their ferritin levels as a defence mechanism. By measuring intracellular H-Fn, we verified whether this interplay between internalized HFn and endogenous H-Fn could be used to maximize HFn uptake and PDT efficacy.Results: We previously demonstrated that HFn-ICG stabilized ICG molecules and increased their delivery to the target site in vitro and in vivo for fluorescence guided surgery. Here, with the aim of using HFn-ICG for PDT, we showed that HFn-ICG improved treatment efficacy in BC cells, depending on their TfR1 expression. Our data revealed that endogenous H-Fn levels were increased after PDT treatment, suggesting that this defence reaction against oxidative stress could be used to enhance HFn-ICG uptake in cells, increasing treatment efficacy.Conclusion: The strong PDT efficacy and peculiar Trojan horse-like mechanism, that we revealed for the first time in literature, confirmed the promising application of HFn-ICG in PDT. Keywords: heavy-ferritin nanocages, indocyanine green, photodynamic therapy, breast cancer, tumor-targeted nanoparticles

Keywords

• heavy ferritin nanocages
• indocyanine green
• photodynamic therapy
• breast cancer
• tumor targeted nanoparticles.