Combined Ferritin Nanocarriers with ICG for Effective Phototherapy Against Breast Cancer

Abstract

Introduction

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.

Graphical Abstract

Keywords:

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

Abbreviations

PDT, photodynamic therapy; PTT, photothermal therapy; ICG, indocyanine green; PS, photosensitizer; HFn, recombinant heavy ferritin; H-Fn, endogenous heavy ferritin; Fn, human protein ferritin; TfR1, transferrin receptor 1; BC, breast cancer; FDA, Food and Drug Administration; NIR, near-infrared; ROS, reactive oxygen species; DNA, Deoxyribonucleic acid; ICD, immunogenic cell death; NPs, nanoparticles; EPR, enhanced permeability and retention; ATCC, American Type Culture Collection; LGC, Laboratory of the Government Chemist; DMEM, Dulbecco’s Modified Eagle Medium; HG, High Glucose; FBS, fetal bovine serum; EDTA, Ethylenediaminetetraacetic Acid; MW, multiwell; min, minutes; h, hours; fps, frames per second; ROI, region of interest; MTS, MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium); PFA, paraformaldehyde; RT, room temperature; BSA, Bovine Serum Albumin; GS, Goat Serum; O/N, Overnight; PBS, Phosphate-Buffered Saline; IPTG, isopropyl β-d-1-tiogalactopiranoside; LB, Luria Bertani; DEAE, Diethylaminoethyl cellulose; LPS, endotoxins/lipopolysaccharides; TEM, transmission electron microscopy; LAL, Limulus amebocyte lysate; EU, endotoxin units; MWCO, molecular weight cutoff; LC, loading capacity; 7-AAD, 7-aminoactinomycin D; M.F.I., mean fluorescence intensity; UHPLC-MS/MS, Ultra High Performance tandem Mass Spectrometry; ESI-MS/MS, electrospray ion source tandem mass spectrometry; CID, collisional-induced dissociation; Rt, retention time.

Data Sharing Statement

Availability of data and materials: Raw data are available in a publicly accessible repository after publication (https://doi.org/10.13130/RD_UNIMI/WYJ0FB).

Acknowledgments

The research leading to these results received funding from AIRC under IG 2017—ID20172 P.I. Corsi and IG2022-ID27107 P.I. Mazzucchelli, and from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant agreement No. 759159-P.I. Saccomandi). We acknowledge the University of Milan for M. S. PhD fellowship and AIRC IG2022-ID27107 P.I. Mazzucchelli for L.S. post-doctoral position. We acknowledge the University of Milan for support in open access publication. Finally, we thank Prof. Nica Borgese for her precious contribution in improving the English language and writing flow of the manuscript thoroughly.

The graphical abstract was created with Biorender.com.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.