Biodegradable nanoplatform upregulates tumor microenvironment acidity for enhanced cancer therapy via synergistic induction of apoptosis, ferroptosis, and anti-angiogenesis

Biosynthetic MnSe nanobomb with low Mn content activates the cGAS-STING pathway and induces immunogenic cell death to enhance antitumour immunity

Triple-negative breast cancer (TNBC) is a relatively "cold" tumour with low immunogenicity compared to other tumour types. Especially, the immune checkpoint inhibitors to treat metastatic TNBC only shows the modest immune response rates. Here, we used Chlorella vulgaris as a bioreactor to synthesize an efficient nanobomb (Bio-MnSe) aimed at eliciting systemic anti-tumour immune response. Despite possessing extremely low Mn content, Bio-MnSe effectively produced more ROS and activated stronger cGAS-STING signal pathway compared to pure Se nanoparticles and free Mn2+ ions, promoting the infiltration of natural killer (NK) cells, cytotoxic T lymphocytes (CTLs) in tumour, effectively turning "cold" tumour into "hot" tumour, and achieving strong antitumour immunotherapy. Additionally, the use of αPD-L1 as an immune checkpoint antagonist further increased the anti-tumour immune response of Bio-MnSe, resulting in enhanced anti-tumour effects. Doxorubicin (Dox), an immunogenic cell death (ICD) inducer, was combined with Bio-MnSe to form Bio-MnSe@Dox. This Bio-MnSe@Dox not only directly damaged tumour cells and induced tumour ICD but also promoted dendritic cell maturation, cytotoxic T lymphocyte infiltration, and NK cell recruitment, synergistically intensifying anti-tumour immune responses and suppressing tumour relapse and lung metastasis. Collectively, our findings propose an effective strategy for transforming 'cold' tumours to 'hot' ones, thereby advancing the development of anti-tumour immune drugs. STATEMENT OF SIGNIFICANCE: A biogenic MnSe (Bio-MnSe) nanocomposite was synthesized using Chlorella vulgaris as a bioreactor for enhanced immunotherapy of TNBC. Bio-MnSe demonstrated a stronger ability to activate the cGAS-STING signalling pathway and generate more ROS compared to pure Se nanoparticles and free Mn2+ ions. Apoptotic cells induced by Bio-MnSe released a significant amount of interferon, leading to the activation of T and natural killer (NK) cells, ultimately transforming immunologically 'cold' breast tumours to 'hot' tumours and enhancing the tumour's response to immune checkpoint inhibitors. The combination of Bio-MnSe with Dox or αPD-L1 further enhanced the anti-tumour immune response, fostering dendritic cell maturation, infiltration of cytotoxic T lymphocytes, and recruitment of NK cells, thereby enhancing the anti-tumour immunotherapy of TNBC.

Emerging mechanisms of ferroptosis and its implications in lung cancer

ABSTRACT

Lung cancer is one of the most common malignancies and has the highest number of deaths among all cancers. Despite continuous advances in medical strategies, the overall survival of lung cancer patients is still low, probably due to disease progression or drug resistance. Ferroptosis is an iron-dependent form of regulated cell death triggered by the lethal accumulation of lipid peroxides, and its dysregulation is implicated in cancer development. Preclinical evidence has shown that targeting the ferroptosis pathway could be a potential strategy for improving lung cancer treatment outcomes. In this review, we summarize the underlying mechanisms and regulatory networks of ferroptosis in lung cancer and highlight ferroptosis-targeting preclinical attempts to provide new insights for lung cancer treatment.

Engineering Iron-Based Nanomaterials for Breast Cancer Therapy Associated with Ferroptosis

Ferroptosis has received increasing attention as a novel nonapoptotic programmed death. Recently, iron-based nanomaterials have been extensively exploited for efficient tumor ferroptosis therapy, as they directly release high concentrations of iron and increase intracellular reactive oxygen species levels. Breast cancer is one of the commonest malignant tumors in women; inhibiting breast cancer cell proliferation through activating the ferroptosis pathway could be a potential new target for patient treatment. Here, we briefly introduce the background of ferroptosis and systematically review the current cancer therapeutic strategies based on iron-based ferroptosis inducers. Finally, we summarize the advantages of these various ferroptosis inducers and shed light on future perspectives. This review aims to provide better guidance for the development of iron-based nanomaterial ferroptosis inducers.

High-Contrast Photoacoustic Imaging of Localized Cysteine in Orthotopic Breast Cancer Enabled by A Totally-Caged Methylene Blue Probe

High-contrast photoacoustic sensing imaging (PASI) was greatly determined by optical absorption changes of the absorbers usually enabled by activatable probes via controllably converting the absorbed electromagnetic energy to ultrasound waves. However, most of current photoacoustic probes still suffer from limited imaging contrast towards specific species because of their small absorption spectral changes in the near infrared (NIR) region. Herein, we developed a methylene blue-based photoacoustic probe with its NIR optical absorption totally caged, which could afford dramatical "OFF-to-ON" absorption transition for high-contrast photoacoustic imaging towards the localized cysteine. The rationally designed methylene blue-based probe for cysteine (MB-Cys) would keep in off state with almost no absorption in NIR region, while upon activated by cysteine through cyclization reaction with acrylates, it would reconstruct the π-conjugation system to release the free methylene blue with strong absorption centered at 665 nm (>130-fold enhancement). The unique responsive behavior could enable the PASI for photoacoustic mapping the cysteine in orthotopic breast cancer in a high-contrast manner. Therefore, this work established an up-to-date strategy to originally eliminate the background photoacoustic signal for PASI to accurately monitor cysteine in vivo.

Tumor Microenvironment ROS/pH Cascade-Responsive Supramolecular Nanoplatform with ROS Regeneration Property for Enhanced Hepatocellular Carcinoma Therapy

The low targeted drug delivery efficiency, including poor tumor accumulation and penetration and uncontrolled drug release, leads to the failure of cancer therapy. Herein, a multifunctional supramolecular nanoplatform loading triptolide (TPL/PBAETK@GA NPs) was fabricated via the host-guest interaction between glycyrrhetinic-acid-modified poly(ethylene glycol)-adamantanecarboxylic acid moiety and reactive oxygen species (ROS)/pH cascade-responsive copolymer poly(β-amino esters)-thioketal (TK)-β-cyclodextrin. TPL/PBAETK@GA NPs could accumulate in hepatocellular carcinoma (HCC) tissue effectively, mediated by nanoscale advantage and GA' recognition to specific receptors. The elevated concentration of ROS in tumor microenvironment (TME) quickly breaks the TK linkages, causing the detachment of shell (cyclodextrin) CD layer. Then, the accompanying negative-to-positive charge-reversal of NPs was realized via the PBAE moiety protonation under the slightly acidic TME, significantly enhancing the NPs' cellular internalization. Remarkably, the pH-responsive endo/lysosome escape of PBAE core triggered intracellular TPL burst release, promoting the cancer cell apoptosis, autophagy, and intracellular ROS generation, leading to the self-amplification of ROS in TME. Afterward, the ROS positive-feedback loop was generated to further promote size-shrinkage and charge-reversal of NPs. Both in vitro and in vivo tests verified that TPL/PBAETK@GA NPs produced a satisfactory anti-HCC therapy outcome. Collectively, this study offers a potential appealing paradigm to enhance TPL-based HCC therapy outcomes via multifunctionalized supramolecular nanodrugs.

Environmental Determinants of Ferroptosis in Cancer

Given the enormous suffering and death associated with human cancers, there is an urgent need for novel therapeutic approaches to target tumor growth and metastasis. While initial efforts have focused on the dysregulated oncogenic program of cancer cells, recent focus has been on the modulation and targeting of many "cancer-friendly," non-genetic tumor microenvironmental factors, which support and enable tumor progression and metastasis. Two prominent examples are anti-angiogenesis and immunotherapy that target tumor-supporting vascularization and the immune-suppressive tumor microenvironment (TME), respectively. Lately, there has been significant interest in the therapeutic potential of ferroptosis, a natural tumor suppression mechanism that normally occurs as a result of oxidative stress, iron imbalance, and accumulation of lipid peroxides. While numerous studies have identified various cell intrinsic mechanisms to protect or promote ferroptosis, the role of various TME stress factors are also recently recognized to modulate the tumor cells' susceptibility to ferroptosis. This review aims to compile and highlight evidence of these factors, how various TME stresses affect ferroptosis, and their implications in various stages of tumor development and expected response to ferroptosis-triggering therapeutics under development. Consequently, understanding ways to enhance ferroptosis sensitivity both intracellularly and in the TME may optimize therapeutic sensitivity to minimize or prevent tumor growth and metastasis.

Anti-Her2 affibody-decorated arsenene nanosheets induce ferroptosis through depleting intracellular GSH to overcome cisplatin resistance

Ferroptosis, a form of regulated cell death induced by excessive accumulation of reactive oxygen species and lipid peroxidation, has recently attracted extensive attention due to its ability to effectively suppress tumors and overcome drug resistance. Unlike previously reported metal nanomaterials that induce ferroptosis via the Fenton reaction, arsenene nanosheets can effectively deplete intracellular glutathione and then induce ferroptosis by inhibiting glutathione peroxidase 4. In this study, we designed target-modified arsenene nanosheets loaded with cisplatin (Her2-ANs@CDDP), which are capable of selective uptake by tumor cells. Her2-ANs@CDDP promotes both apoptosis and ferroptosis through a reciprocal cascade reaction between cisplatin and the carrier, respectively, and we demonstrate that it can significantly inhibit the activity of drug-resistant cells. Arsenene nanosheets kill drug-resistant tumor cells by inducing ferroptosis and restoring the sensitivity of drug-resistant cells to cisplatin. Cisplatin-loaded arsenene nanosheets can be prepared simply, and exert synergistic effects that overcome drug resistance. They show great potential for applications in the clinical treatment of chemotherapy-insensitive osteosarcoma, expanding the uses of arsenic in the treatment of solid tumors.