GSH-responsive SN38 dimer-loaded shape-transformable nanoparticles with iRGD for enhancing chemo-photodynamic therapy

Sulfasalazine Sensitizes Polyhematoporphyrin-Mediated Photodynamic Therapy in Cholangiocarcinoma by Targeting xCT

Cholangiocarcinoma (CCA), which is highly malignant, shows a relatively poor prognosis, due to the insensitivity of the tumour to chemotherapy and radiotherapy. Photodynamic therapy (PDT) has become a promising palliative therapeutic option for patients with unresectable cholangiocarcinoma (CCA), while the functional amount of ROS is limited by intracellular redox systemen. Sulfasalazine (SASP), a well-known anti-inflammatory agent, which also acts as an inhibitor of the amino acid transport system xc (xCT), decreases the intracellular glutathione (GSH) level, thus weakening the antioxidant defence of the cell by inhibition of the antiporter. However, the combination of SASP and PDT remains unexplored. We have reported that polyhematoporphyrin (PHP)-mediated PDT inhibits the cell viability of CCA cells and organoids. Furthermore, in PHP-enriched HCCC-9810 and TFK-1CCA cells, SASP enhances the sensitivity to PHP-mediated PDT through a GSH-dependent mechanism. We found that PHP-PDT can up-regulate xCT expression to promote cells against overloaded ROS, while SASP reduces GSH levels. After the combination of SASP and PHP-PDT, cell viability and GSH levels were significantly inhibited. xCT was also observed to be inhibited by SASP in human organoid samples. Our findings suggest that, in combination with PDT, SASP has potential as a promising approach against CCA.

Nanoengineering of a newly designed chlorin e6 derivative for amplified photodynamic therapy via regulating lactate metabolism

Chlorin e6 (Ce6) is a widely utilized photosensitizer in photodynamic therapy (PDT) against tumor growth, but its hydrophobic feature and the hypoxia in the tumor microenvironment greatly compromise its therapeutic efficacy. To address the issues, here we designed a new Ce6 derivative (TCe6) by coupling Ce6 with amphiphilic d-α-tocopherol polyethylene glycol 1000 succinate (TPGS), endowing Ce6 with an excellent amphiphilic feature. In particular, the overall reactive oxygen species (ROS) generation by TCe6 was significantly enhanced because TPGS could interact with mitochondrial complex II to induce extra ROS production, amplifying the total ROS production under PDT. Inspired by the unique property of α-cyano-4-hydroxycinnamate (CHC) in regulating lactate metabolism to spare more intracellular oxygen for PDT, TCe6 was further co-assembled with CHC to construct TCe6/CHC nanoparticles (NPs) for addressing the insufficient oxygen issue in PDT. The as-prepared TCe6/CHC NPs not only increased the efficiency of cell internalization but also improved the solubility and stability of Ce6 and CHC. Thanks to the extra ROS production by the TPGS unit, the amphiphilic feature of TCe6 and the CHC-mediated hypoxia microenvironment, the TCe6/CHC NPs demonstrated excellent PDT against tumor growth. This work provided a versatile strategy to solve the current bottleneck in photosensitizer-based PDT, holding great promise for the design of advanced photodynamic nanoplatforms.

Doxorubicin-Bound Hydroxyethyl Starch Conjugate Nanoparticles with pH/Redox Responsive Linkage for Enhancing Antitumor Therapy

BACKGROUND

Chemotherapeutic drugs used for tumor treatments often show limited efficiency due to their short lifetime, nonspecific delivery, and slow or insufficient intracellular drug release, and also, they can cause severe system or organ toxicity. The development of chemotherapeutic nanomedicines with high efficacy and satisfactory safety still remains a challenge for current tumor chemotherapy.

METHODS

A novel type of conjugate was synthesized using hydroxyethyl starch (HES) as a carrier while binding doxorubicin (DOX) onto HES backbone through a pH/redox responsive linker containing both disulfide and hydrazone bonds in series. The built conjugates were self-assembled into nanoparticles (NPs) (HES-SS-hyd-DOX NPs) for achieving enhanced antitumor therapy and adequate safety.

RESULTS

HES-SS-hyd-DOX NPs had a certain ability for the tumor-orientated drug accumulation and were capable of releasing DOX itself rather than DOX derivatives. It was found that the pH/redox responsive linkage enabled the NPs to achieve fast and sufficient intracellular drug release. Based on the tumor-bearing mouse model, antitumor results demonstrated that these NPs were able to inhibit the growth of the advanced tumors with significantly enhanced efficacy when compared to free DOX, and to those conjugate NPs containing only a single responsive or unresponsive bond. Besides, HES-SS-hyd-DOX NPs also showed adequate safety to the normal organs of the treated mice.

CONCLUSION

The pH/redox responsive linkage in HES-SS-hyd-DOX was found to play a critical role in mediating the drug accumulation and the fast and sufficient intracellular drug release. The HES-exposed surface of HES-SS-hyd-DOX NPs endowed the NPs with long circulation capability and remarkably reduced the DOX-induced side effects.

Nanovaccine-Based Strategies to Overcome Challenges in the Whole Vaccination Cascade for Tumor Immunotherapy

Nanovaccine-based immunotherapy (NBI) has received greater attention recently for its potential to prime tumor-specific immunity and establish a long-term immune memory that prevents tumor recurrence. Despite encouraging results in the recent studies, there are still numerous challenges to be tackled for eliciting potent antitumor immunity using NBI strategies. Based on the principles that govern immune response, here it is proposed that these challenges need to be addressed at the five critical cascading events: Loading tumor-specific antigens by nanoscale drug delivery systems (L); Draining tumor antigens to lymph nodes (D); Internalization by dendritic cells (DCs) (I); Maturation of DCs by costimulatory signaling (M); and Presenting tumor-peptide-major histocompatibility complexes to T cells (P) (LDIMP cascade in short). This review provides a detailed and objective overview of emerging NBI strategies to improve the efficacy of nanovaccines in each step of the LDIMP cascade. It is concluded that the balance between each step must be optimized by delicate designing and modification of nanovaccines and by combining with complementary approaches to provide a synergistic immunity in the fight against cancer.

Furin-instructed aggregated gold nanoparticles for re-educating tumor associated macrophages and overcoming breast cancer chemoresistance

Insufficient drug accumulation and chemoresistance remain two major challenges in cancer chemotherapy. Herein, we designed a furin-responsive aggregated nanoplatform loaded with doxorubicin (DOX) and hydroxychloroquine (HCQ) (AuNPs-D&H-R&C) to combine chemotherapy, autophagy inhibition and macrophage polarization. AuNPs-D&H-R&C could passively target breast tumor via enhanced permeability and retention (EPR) effect after systemic administration and further aggregate together triggered by furin overexpressed in breast cancer. The in situ aggregations hindered the back-flow of NPs to the bloodstream and exocytosis of tumor cells, leading to enhanced drug accumulation within tumors. Moreover, upon exposure to acidic pH in the endosomes/lysosomes, HCQ was efficiently released and it inhibited autophagy and thus restored the sensitivity of tumor cell to DOX. Meanwhile, autophagy inhibition could reprogram tumor-promoting M2-like TAMs to anti-tumor M1 phenotype, exerting a synergistic effect in overcoming chemoresistance. In vitro studies demonstrated the superiority of furin-triggered aggregated AuNPs delivery system in enhancing drug accumulation in breast tumor, compared with PEGlyated AuNPs. The co-delivery of DOX and HCQ showed much improved chemotherapeutic efficiency to chemoresistant MCF-7/ADR breast tumor, in large part due to macrophage polarization. In conclusion, we developed a stimulus-responsive delivery system and proposed a potential combination strategy to overcome chemoresistance in cancer chemotherapy.

An Amphiphilic PEGylated Peptide Dendron-Gemcitabine Prodrug-Based Nanoagent for Cancer Therapy

An amphiphilic peptide dendrimer conjugated with gemcitabine (GEM), PEGylated dendron-Gly-Phe-Leu-Gly-GEM (PEGylated dendron-GFLG-GEM), is developed as a nano-prodrug for breast cancer therapy. The self-assembled behavior is observed under a transmission electron microscopy and dynamic light scattering. The negatively charged surface and hydrodynamic size of the amphiphilic nanosized prodrug supported that the prodrug can maintain the stability of GEM during circulation and accumulate in the tumor tissue. Drug release assays are conducted to monitor the release of GEM from this nanodrug delivery system in response to the tumor microenvironment, and these assays confirm that GEM released from the nanocarrier is identical to free GEM. The GEM prodrug can prevent proliferation of tumor cells. The therapeutic effect against breast cancer is systematically investigated using an in vivo animal model. Immunohistochemical results are aligned with the significantly enhanced anticancer efficacy of GEM released from the prodrug. This self-assembled amphiphilic drug delivery nanocarrier may broaden the application for GEM and other anticancer agents for breast cancer chemotherapy.