Redox-sensitive iodinated polymersomes carrying histone deacetylase inhibitor as a dual-functional nano-radiosensitizer for enhanced radiotherapy of breast cancer

Ferroptosis: Frenemy of Radiotherapy

Recently, it was established that ferroptosis, a type of iron-dependent regulated cell death, plays a prominent role in radiotherapy-triggered cell death. Accordingly, ferroptosis inducers attracted a lot of interest as potential radio-synergizing drugs, ultimately enhancing radioresponses and patient outcomes. Nevertheless, the tumor microenvironment seems to have a major impact on ferroptosis induction. The influence of hypoxic conditions is an area of interest, as it remains the principal hurdle in the field of radiotherapy. In this review, we focus on the implications of hypoxic conditions on ferroptosis, contemplating the plausibility of using ferroptosis inducers as clinical radiosensitizers. Furthermore, we dive into the prospects of drug repurposing in the domain of ferroptosis inducers and radiosensitizers. Lastly, the potential adverse effects of ferroptosis inducers on normal tissue were discussed in detail. This review will provide an important framework for subsequent ferroptosis research, ascertaining the feasibility of ferroptosis inducers as clinical radiosensitizers.

Heterocyclic Molecular Targeted Drugs and Nanomedicines for Cancer: Recent Advances and Challenges

Cancer is a top global public health concern. At present, molecular targeted therapy has emerged as one of the main therapies for cancer, with high efficacy and safety. The medical world continues to struggle with the development of efficient, extremely selective, and low-toxicity anticancer medications. Heterocyclic scaffolds based on the molecular structure of tumor therapeutic targets are widely used in anticancer drug design. In addition, a revolution in medicine has been brought on by the quick advancement of nanotechnology. Many nanomedicines have taken targeted cancer therapy to a new level. In this review, we highlight heterocyclic molecular-targeted drugs as well as heterocyclic-associated nanomedicines in cancer.

Nanoparticle-Mediated Radiotherapy Remodels the Tumor Microenvironment to Enhance Antitumor Efficacy

Radiotherapy (RT) uses ionizing radiation to eradicate localized tumors and, in rare cases, control tumors outside of the irradiated fields via stimulating an antitumor immune response (abscopal effect). However, the therapeutic effect of RT is often limited by inherent physiological barriers of the tumor microenvironment (TME), such as hypoxia, abnormal vasculature, dense extracellular matrix (ECM), and an immunosuppressive TME. Thus, it is critical to develop new RT strategies that can remodel the TME to overcome radio-resistance and immune suppression. In the past decade, high-Z-element nanoparticles have been developed to increase radiotherapeutic indices of localized tumors by reducing X-ray doses and side effects to normal tissues and enhance abscopal effects by activating the TME to elicit systemic antitumor immunity. In this review, the principles of RT and radiosensitization, the mechanisms of radio-resistance and immune suppression, and the use of various nanoparticles to sensitize RT and remodel TMEs for enhanced antitumor efficacy are discussed. The challenges in clinical translation of multifunctional TME-remodeling nanoradiosensitizers are also highlighted.

Folate Decorated Multifunctional Biodegradable Nanoparticles for Gastric Carcinoma Active Targeting Theranostics

Introduction

Gastric cancer remains a major clinical issue and little progress has been made in the treatment of gastric cancer patients during recent decades. Nanoparticles provide a versatile platform for the diagnosis and treatment of gastric cancer.

Methods

We prepared 7-ethyl-10-hydroxycamptothecin (SN-38) ¹²⁵I-radiolabelled biodegradable nanoparticles with folate surface modification (¹²⁵I-SN-38-FA-NPs) as a novel nanoplatform for targeted gastric carcinoma theranostics. We characterized this system in terms of particle size, morphology, radiostability, and release properties and examined the in vitro cytotoxicity and cellular uptake properties of ¹²⁵I-SN-38-FA-NPs in MNK 7 and NCI-N7 cells. The pharmacokinetics and biodistribution of ¹²⁵I-SN-38-FA-NPs were imaged by single photon emission computer tomography (SPECT). An MNK7 tumor-bearing model were established and the in vivo antitumor activity of ¹²⁵I-SN-38-FA-NPs was evaluated.

Results

SN-38 was readily radiolabeled with ¹²⁵I and exhibited high radiostability. Poly-lactic-co-glycolic acid (PLGA) nanoparticles (NPs) were formed by solvent exchange, and displayed spherical morphology of 100 nm in diameter as characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). A 2.5-fold greater uptake of ¹²⁵I-radiolabelled SN-38-loaded folate-decorated PLGA nanoparticles (¹²⁵I-SN-38-FA-NPs) than ¹²⁵I-radiolabelled SN-38-loaded PLGA nanoparticles (¹²⁵I-SN-38-NPs) were record in MKN7 tumor cells. NPs and folate-decorated PLGA nanoparticles (FA-NPs) also had good biocompatibility in methyl thiazolyl tetrazolium (MTT) assays. Pharmacokinetic, biodistribution and SPECT imaging studies showed that ¹²⁵I-SN-38-FA-NPs had prolonged circulation, were distributed in the reticuloendothelial system, and had high uptake in tumors with a higher tumor accumulation of ¹²⁵I-SN-38-FA-NPs than ¹²⁵I-SN-38-NPs recorded at 24 h postinjection. In vivo SN-38-FA-NPs significantly inhibited tumor growth without causing obvious side effects.

Conclusion

Folate receptor alpha (FOLR1) targeted drug-loaded nanoparticles enable SPECT imaging and chemotherapy, and provide a novel nanoplatform for gastric carcinoma active targeting theranostics.

Nanomaterials Based on Functional Polymers for Sensitizing Cancer Radiotherapy

Despite being the mainstay treatment for many types of cancer in clinic, radiotherapy is undertaking great challenges in overcoming a series of limitations. Radiosensitizers are promising agents capable of depositing irradiation energy and generating free radicals to enhance the radiosensitivity of tumor cells. Combining radiosensitizers with functional polymer-based nanomaterials holds great potential to improve biodistribution, circulation time, and stability in vivo. The derived polymeric nano-radiosensitizers can significantly improve the efficiency of tumor targeting and radiotherapy, and reduce the side effect to healthy tissues. In this review, we provide an overview of functional polymer-based nanomaterials for radiosensitization in recent years. Particular emphases are given to the action mechanisms, drug loading methods, targeting efficiencies, the impact on therapeutic effects and biocompatibility of various radiosensitizing polymers, which are classified as polymeric micelles, dendrimers, polymeric nanospheres, nanoscale coordination polymers, polymersomes, and nanogels. The challenges and outlooks of polymeric nano-radiosensitizers are also discussed. This article is protected by copyright. All rights reserved.