Dual GSH-exhausting sorafenib loaded manganese-silica nanodrugs for inducing the ferroptosis of hepatocellular carcinoma cells

RRM2 protects against ferroptosis and is a tumor biomarker for liver cancer

Background

Ferroptosis is the process of cell death triggered by lipid peroxides, and inhibition of glutathione (GSH) synthesis leads to ferroptosis. Liver cancer progression is closely linked to ferroptosis suppression. However, the mechanism by which inhibition of GSH synthesis suppresses potential ferroptosis of liver cancer cells and whether ferroptosis-related liver cancer biomarkers have a promising diagnostic value remain unknown.

Methods

Ribonucleotide reductase regulatory subunit M2 (RRM2) levels were measured using an enzyme linked immunosorbent assay (ELISA), quantitative RT-PCR (qPCR), immunoblotting (IB) and immunochemistry (IHC). Cell viability and cell death were measured by a CellTiter-Glo luminescent cell viability assay and staining with SYTOX Green followed by flow cytometry, respectively. Metabolites were measured using the indicated kits. The Interaction between glutathione synthetase (GSS) and RRM2 was measured using immunofluorescence (IF), co-immunoprecipitation (co-IP) and the proximal ligation assay (PLA). The diagnostic value was analyzed using the area under the receiver operating characteristic curve (AUC-ROC). Bioinformatics analysis was performed using the indicated database.

Results

RRM2 showed specifically elevated levels in liver cancer and inhibited ferroptosis by stimulating GSH synthesis via GSS. Mechanistically, phosphorylation of RRM2 at the Threonine 33 residue (T33) was maintained at normal levels to block the RRM2–GSS interaction and therefore protected RRM2 and GSS from further proteasome degradation. However, under ferroptotic stress, RRM2 was dephosphorylated at T33, thus the RRM2–GSS interaction was promoted. This resulted in the translocation of RRM2 and GSS to the proteasome for simultaneous degradation. Clinically, serum RRM2 was significantly associated with serum alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma glutamyl transpeptidase (γ-GT), albumin (ALB) and total bilirubin. The AUC-ROC for the combination of RRM2 with AFP was 0.947, with a sensitivity of 88.7% and a specificity of 97.0%, which indicates better diagnostic performance compared to either RRM2 or AFP alone.

Conclusion

RRM2 exerts an anti-ferroptotic role in liver cancer cells by sustaining GSH synthesis. Serum RRM2 will be useful as a biomarker to evaluate the degree to which ferroptosis is suppressed and improve diagnostic efficiency for liver cancer.

Antineoplastic behavior of polydopamine nanoparticles prepared in different water/alcohol media

Polydopamine nanoparticles (PD NPs) have been synthesized in the present work through the oxidative polymerization of dopamine in aqueous media containing five different types of alcohol in a constant solvent volume ratio. We have shown that the type of alcohol, along with the ammonium hydroxide concentration used in the synthesis process, conditions particle size. Additionally, it has been found that the type of alcohol employed influences the well-known capacity of polydopamine nanoparticles to adsorb iron. As a consequence, since a ferroptosis-like mechanism may account for the cytotoxicity of these nanoparticles, the type of alcohol could also have a determining role in their antineoplastic activity. Here, the existence of a correlation between the ability of polydopamine nanoparticles to load Fe³⁺ and their toxic effect on breast cancer cells has been proven. For instance, nanoparticles synthesized using 2-propanol adsorbed more Fe³⁺ and had the greatest capacity to reduce breast tumor cell viability. Moreover, none of the nanoparticle synthesized with the different alcohols significantly decreased normal cell survival. Cancer cells present greater iron-dependence than healthy cells and this fact may explain why polydopamine nanoparticles toxicity, in which Fenton chemistry could be implicated, seems tumor-specific.

Ferroptosis as a novel form of regulated cell death: Implications in the pathogenesis, oncometabolism and treatment of human cancer

The treatment of cancer mainly involves surgical excision supplemented by radiotherapy and chemotherapy. Chemotherapy drugs act by interfering with tumor growth and inducing the death of cancer cells. Anti-tumor drugs were developed to induce apoptosis, but some patient’s show apoptosis escape and chemotherapy resistance. Therefore, other forms of cell death that can overcome the resistance of tumor cells are important in the context of cancer treatment. Ferroptosis is a newly discovered iron-dependent, non-apoptotic type of cell death that is highly negatively correlated with cancer development. Ferroptosis is mainly caused by the abnormal increase in iron-dependent lipid reactive oxygen species and the imbalance of redox homeostasis. This review summarizes the progression and regulatory mechanism of ferroptosis in cancer and discusses its possible clinical applications in cancer diagnosis and treatment.

Emerging Strategies in Anticancer Combination Therapy Employing Silica-Based Nanosystems

Combination therapy has emerged as one of the most promising approaches for cancer treatment. However, beyond remotely-triggered therapies that require advanced infrastructures and optimization, new combination therapies based on internally triggered cell-killing effects have also demonstrated promising therapeutic profiles. In this revision, the focus is on self-triggered strategies able to improve the therapeutic effect of drug delivery nanosystems. As reviewed, ferroptosis, hypoxia, and immunotherapy show potency enough to treat satisfactorily tumors in vivo. However, the interest of combining those with chemotherapeutics, especially with carriers based on mesoporous silica, has provided a new generation of therapeutic nanomedicines with potential enough to achieve complete tumor remission in murine models.

Recent advances of sorafenib nanoformulations for cancer therapy: Smart nanosystem and combination therapy

Sorafenib, a molecular targeted multi-kinase inhibitor, has received considerable interests in recent years due to its significant profiles of efficacy in cancer therapy. However, poor pharmacokinetic properties such as limited water solubility, rapid elimination and metabolism lead to low bioavailability, restricting its further clinical application. Over the past decade, with substantial progress achieved in the development of nanotechnology, various types of smart sorafenib nanoformulations have been developed to improve the targetability as well as the bioavailability of sorafenib. In this review, we summarize various aspects from the preparation and characterization to the evaluation of antitumor efficacy of numerous stimuli-responsive sorafenib nanodelivery systems, particularly with emphasis on their mechanism of drug release and tumor microenvironment response. In addition, this review makes great effort to summarize the nanosystem-based combination therapy of sorafenib with other antitumor agents, which can provide detailed information for further synergistic cancer therapy. In the final section of this review, we also provide a detailed discussion of future challenges and prospects of designing and developing ideal sorafenib nanoformulations for clinical cancer therapy.

Targeted GSH-exhausting and hydroxyl radical self-producing manganese-silica nanomissiles for MRI guided ferroptotic cancer therapy

Ferroptosis, a cell death path induced by the generation of reactive oxygen species (ROS), will cause the accumulation of lipid peroxides (PL-PUFA-OOH) and achieve potent tumor-regression. However, glutathione (GSH)-dependent glutathione peroxidase 4 (GPx4) can reduce PL-PUFA-OOH and antagonize the ferroptosis inducing effect of ROS. Herein, folate-PEG modified dihydroartemisinin (DHA) loaded manganese doped mesoporous silica nanoparticles (described as nanomissiles) were constructed for integrating the effect of GSH exhaustion and ROS generation. After endocytosis by tumor cells, intracellular GSH triggered the degradation of nanomissiles, which allowed the simultaneous release of DHA and Fenton catalytic Mn2+ due to the redox reaction between the manganese-oxygen bonds and GSH. The degradation would lead to GSH exhaustion, activation of Mn2+-based magnetic resonance imaging (MRI), and DHA-driven ˙OH generation. The GSH-free environment inhibited the activity of GPx4 and enhanced the accumulation of PL-PUFA-OOH oxidized by ˙OH. Furthermore, the cooperative effects suppressed tumor metastasis by destroying the structure of polyunsaturated fatty acids in the cell membranes and showed potent antitumor activity. This innovative ferroptotic therapy integrating the GSH exhaustion and ROS generation will be a promising strategy for cancer therapy.

Targeted Manganese doped silica nano GSH-cleaner for treatment of Liver Cancer by destroying the intracellular redox homeostasis

Background: Glutathione (GSH), the primary antioxidant in cells, could fight against oxidative stress. Tumor cells display a higher GSH level than normal cells for coping with the hyperoxidative state, which meets the requirements of enhanced metabolism and vicious proliferation. Therefore, the consumption of GSH will lead to cell redox imbalance and impede life activities. Herein, targeted sorafenib (SFB) loaded manganese doped silica nanoparticle (FaPEG-MnMSN@SFB) was constructed, which could destroy the intracellular redox homeostasis by consuming GSH. Methods: In this study, MnMSN was prepared by an optimized one-pot Stober's method for loading SFB, and FaPEG chain was modified on the surface of MnMSN to achieve long circulation and targeted delivery. The anticancer efficacy and mechanism of the designed FaPEG-MnMSN@SFB were assessed both in vitro and in vivo.Results: FaPEG-MnMSN@SFB exhibited efficient antitumor activity by dual depleting intracellular GSH (the degradation of MnMSN would consume intracellular GSH and the SFB would inhibit the effect of Xc- transport system to inhibit GSH synthesis). Moreover, disruption of redox balance would lead to apoptosis and reactive oxygen species (ROS)-dependent ferroptosis of tumor cells. Conclusion: Such a GSH-starvation therapeutic strategy would cause multi-path programmed cell death and could be a promising strategy for cancer therapy.

Crosstalk between noncoding RNAs and ferroptosis: new dawn for overcoming cancer progression

Cancer progression including proliferation, metastasis, and chemoresistance has become a serious hindrance to cancer therapy. This phenomenon mainly derives from the innate insensitive or acquired resistance of cancer cells to apoptosis. Ferroptosis is a newly discovered mechanism of programmed cell death characterized by peroxidation of the lipid membrane induced by reactive oxygen species. Ferroptosis has been confirmed to eliminate cancer cells in an apoptosis-independent manner, however, the specific regulatory mechanism of ferroptosis is still unknown. The use of ferroptosis for overcoming cancer progression is limited. Noncoding RNAs have been found to play an important roles in cancer. They regulate gene expression to affect biological processes of cancer cells such as proliferation, cell cycle, and cell death. Thus far, the functions of ncRNAs in ferroptosis of cancer cells have been examined, and the specific mechanisms by which noncoding RNAs regulate ferroptosis have been partially discovered. However, there is no summary of ferroptosis associated noncoding RNAs and their functions in different cancer types. In this review, we discuss the roles of ferroptosis-associated noncoding RNAs in detail. Moreover, future work regarding the interaction between noncoding RNAs and ferroptosis is proposed, the possible obstacles are predicted and associated solutions are put forward. This review will deepen our understanding of the relationship between noncoding RNAs and ferroptosis, and provide new insights in targeting noncoding RNAs in ferroptosis associated therapeutic strategies.

Resibufogenin inhibited colorectal cancer cell growth and tumorigenesis through triggering ferroptosis and ROS production mediated by GPX4 inactivation

Resibufogenin (RB) has been used for cancer treatment, but the underlying mechanisms are still unclear. This study aimed to investigate the effects of RB treatment on colorectal cancer (CRC) cells, and to determine the underlying mechanisms. The cell counting kit-8 assay was used to determine cell viability. Cell morphology was observed under light microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay was employed to detect cell apoptosis. Intracellular ferrous iron (Fe²⁺ ), malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species levels were detected by using commercial iron assay kit, MDA assay kit, GSH assay kit, and 2,7-dichlorodihydrofluorescein diacetate probes, respectively. The protein expressions were determined by Western blot and immunohistochemistry. RB inhibited cell viability in the CRC cell lines (HT29 and SW480) in a dose- and time-dependent manner, and caused cytotoxicity to the normal colonic epithelial cell line (NCM460) at high dose. Similarly, RB induced morphological changes in CRC cells from normal to round shape, and promoted cell death. Of note, RB triggered oxidative stress and ferroptotic cell death in CRC cells, and only ferroptosis inhibitors (deferoxamine and ferrostatin-1), instead of inhibitors for other types of cell death (apoptosis, autophagy, and necroptosis), reversed the inhibitory effects of RB on CRC cell proliferation. Furthermore, glutathione peroxidase 4 (GPX4) was inactivated by RB treatment, and overexpression of GPX4 alleviated RB-induced oxidative cell death in CRC cells. Consistently, the in vivo experiments validated that RB also triggered oxidative stress, and inhibited CRC cells growth and tumorigenicity in mice models. RB can inhibit CRC cells growth and tumorigenesis by triggering ferroptotic cell death in a GPX4 inactivation-dependent manner.