Recent Progresses in Cancer Nanotherapeutics Design Using Artemisinins as Free Radical Precursors

Tween 80 Micelles Loaded with Fe3O4 Nanoparticles and Artemisinin for Combined Oxygen-Independent Ferroptosis Therapy of Cancer

Artemisinin has an endoperoxide bridge structure, which can be cleaved by ferrous ions to generate various carbonyl radicals in an oxygen-independent manner, highlighting its potential for treating hypoxic tumors. In our study, we fabricated Tween 80 micelles loaded with Fe3O4 nanoparticles and artemisinin for cancer therapy. The synthesized Fe3O4 nanoparticles and drug-loaded micelles have particle sizes of about 5 nm and 80 nm, respectively, both exhibiting excellent dispersibility and stability. After uptake by MCF-7 cells, drug-loaded micelles release Fe2+ and ART into the cytoplasm, effectively inducing the generation of reactive oxygen species (ROS) in hypoxic conditions, thereby enhancing toxicity against cancer cells. In vitro and in vivo studies have demonstrated that ART and Fe3O4 nanoparticles are encapsulated in Tween 80 to form micelles, which effectively prevent premature release during circulation in the body. Although free ART and Fe3O4 nanoparticles can inhibit tumor growth, TW80-Fe3O4-ART micelles demonstrate a more pronounced inhibitory effect, with a tumor suppression rate of up to 85%. A novel strategy based on artemisinin and ferroptosis is thus offered, holding a favorable prospect for hypoxic cancer therapy.

GPX4 inhibition synergistically boosts mitochondria targeting nanoartemisinin-induced apoptosis/ferroptosis combination cancer therapy

Artemisinin, originally used for its antimalarial activity, has received much attention in recent years for cancer therapy. The anticancer mechanisms of artemisinin are complicated and debatable. Challenges in the delivery of artemisinin also persist because the anticancer effect of artemisinin alone is often not satisfactory when used with traditional nanocarriers. We herein report the mitochondrial delivery of artemisinin with extremely high anticancer capacity. The action mode of artemisinin in the mitochondria of cancer cells includes heme-participating and oxygen-independent conversion of artemisinin into a carbon-centered radical, which is partly converted into ROS in the presence of molecular oxygen. We reveal that artemisinin alone in the mitochondria can induce strong cancer cell apoptosis. In addition, due to the weak inhibition of GPX4 activity by artemisinin, weak ferroptosis is also observed. We further discover that GPX4 activity in MCF-7 cells is greatly inhibited by RSL3 to synergistically enhance the anticancer capacity of artemisinin via enhancing ferroptosis. The synergistic anticancer activity of artemisinin and RSL3 in the mitochondria not only improves cancer cell-killing ability, but also inhibits the re-proliferation of residual cancer cells. This study provides a new insight into developing highly efficient and practical artemisinin nanomedicines for cancer therapy.

Artemisinin-Type Drugs in Tumor Cell Death: Mechanisms, Combination Treatment with Biologics and Nanoparticle Delivery

Artemisinin, the most famous anti-malaria drug initially extracted from Artemisia annua L., also exhibits anti-tumor properties in vivo and in vitro. To improve its solubility and bioavailability, multiple derivatives have been synthesized. However, to reveal the anti-tumor mechanism and improve the efficacy of these artemisinin-type drugs, studies have been conducted in recent years. In this review, we first provide an overview of the effect of artemisinin-type drugs on the regulated cell death pathways, which may uncover novel therapeutic approaches. Then, to overcome the shortcomings of artemisinin-type drugs, we summarize the recent advances in two different therapeutic approaches, namely the combination therapy with biologics influencing regulated cell death, and the use of nanocarriers as drug delivery systems. For the former approach, we discuss the superiority of combination treatments compared to monotherapy in tumor cells based on their effects on regulated cell death. For the latter approach, we give a systematic overview of nanocarrier design principles used to deliver artemisinin-type drugs, including inorganic-based nanoparticles, liposomes, micelles, polymer-based nanoparticles, carbon-based nanoparticles, nanostructured lipid carriers and niosomes. Both approaches have yielded promising findings in vitro and in vivo, providing a strong scientific basis for further study and upcoming clinical trials.

Artemisinin displays bactericidal activity via copper-mediated DNA damage

Artemisinin (ARS) and its semi-synthetic derivatives are effective drugs to treat malaria and possess multiple therapeutic activities based on their endoperoxide bridge. Here, we showed that ARS displayed antibacterial efficacy in Drosophila systemic infections caused by bacterial pathogens but killed only Vibrio cholerae (VC) in vitro, involving reactive oxygen species (ROS) generation and/or DNA damage. This selective antibacterial activity of ARS was attributed to the higher intracellular copper levels in VC, in that the antibacterial activity was observed in vitro upon addition of cuprous ions even against other bacteria and was compromised by the copper-specific chelators neocuproine (NC) and triethylenetetramine (TETA) in vitro and in vivo. We suggest that copper can enhance or reinforce the therapeutic activities of ARS to be repurposed as an antibacterial drug for the treatment of bacterial infections.

Effects of nanocapsules of poly-ε-caprolactone containing artemisinin on zebrafish early-life stages and adults

Artemisinin extracted from Artemisia annua L. plants has a range of properties that qualifies it to treat several diseases, such as malaria and cancer. However, it has short half-life, which requires making continuous use of it, which has motivated the association of artemisinin (ART) with polymeric nanoparticles to increase its therapeutic efficiency. However, the ecotoxicological safety of this association has been questioned, given the scarcity of studies in this area. Thus, in this work the toxicity of Poly (ε-Caprolactone) nanocapsules added with ART (ART-NANO) in zebrafish (Danio rerio), embryos and adults was studied. Different endpoints were analyzed in organisms exposed to ART-NANO, including those predictive of embryotoxicity and histopatoxicity. Embryotoxicity was analyzed based on Organization for Economic Co-operation and Development (OECD) test guideline (236) for fish embryo acute toxicity applied to zebrafish (Danio rerio) at 96 hpf under five nominal logarithmic concentrations (0.125 to 2.0 mg/ L). Our results demonstrate, mainly, that fertilized eggs presented increased coagulation, lack of heart rate, vitelline sac displacement and lack of somite formation. On the other hand, adult individuals (exposed to the same concentrations and evaluated after 24 and 96 h of exposure) have shown increased pericarditis. Therefore, the treatment based on ART, poly (ε-caprolactone) nanocapsules and on their combination at different concentrations have shown toxic effects on zebrafish embryos and adult individuals.

tLyP-1 Peptide Functionalized Human H Chain Ferritin for Targeted Delivery of Paclitaxel

PURPOSE

The aims of this study were to test the feasibility, targeting specificity and anticancer therapeutic efficacy of CendR motif tLyP-1 functionalized at the N-terminal of ferritin for paclitaxel (PTX) delivery.

METHODS

A tumor homing and penetrating peptide tLyP-1 was fused to the N-terminal of human H chain ferritin (HFtn) to generate a dual-targeting nanoparticle delivery system. PTX molecules were encapsulated into the HFtn nanocage using the disassembly/assembly method by adjusting pHs. Cellular uptake was examined by confocal laser scanning microscopy (CLSM) and flow cytometry. The MTT assay was used to test the cytotoxicity of various PTX-loaded NPs against MDA-MB-231 and SMMC-7721 tumor cells. The wound healing and cell migration assays were conducted to assess the inhibitory effect on cell motility and metastasis. The inhibition effect on the SMMC-7721 tumor spheroids was studied and penetration ability was evaluated by CLSM. The antitumor efficacy of PTX-loaded NPs was assessed in MDA-MB-231 breast cancer xenografted in female BALB/c nude mice.

RESULTS

Compared with HFtn-PTX, in vitro studies demonstrated that the tLyP-1-HFtn-PTX displayed enhanced intracellular delivery and better cytotoxicity and anti-invasion ability against both SMMC-7721 and MDA-MB-231 cells. The better penetrability and growth inhibitory effect on SMMC-7721 tumor spheroids were also testified. In vivo distribution and imaging demonstrated that the tLyP-1-HFtn-PTX NPs were selectively accumulated and penetrated at the tumor regions. Verified by the breast cancer cells model in BABL/c nude mice, tLyP-1-HFtn-PTX displayed higher in vivo therapeutic efficacy with lower systemic toxicity.

CONCLUSION

Ferritin decorated with tumor-homing penetration peptide tLyP-1 at the N terminal could deliver PTX specifically inside the cell via receptor-mediated endocytosis with better efficacy. The peptide tLyP-1 which is supposed to work only at the C terminus showed enhanced tumor tissue penetration and antitumor efficacy, demonstrating that it also worked at the N-terminal of HFtn.