Ferroptosis: An emerging approach for targeting cancer stem cells and drug resistance

Ferroptosis in cancer: Mechanisms, therapeutic strategies, and clinical implications

The resistance of cancer cells to existing treatments has become a major challenge for researchers despite advancements in cancer treatment. Studies have shown that this resistance is due to cancer cells evading apoptosis. Moreover, the most common form of cell death induced by chemotherapy and radiotherapy is apoptosis. One of the most essential mechanisms cancer cells escape apoptosis is the excessive expression of tumors' apoptosis inhibitors. Therefore, finding a non-apoptotic pathway that bypasses apoptosis could be a hopeful strategy for cancer treatment. Ferroptosis has been identified as a non-apoptotic and regulated cell death process characterized by the accumulation of lipid peroxides and iron-dependent reactive oxygen species (ROS). Although studies have shown that ferroptosis plays a role in the development of many diseases, including cancer, it also has the potential to decrease resistance to current treatments, such as chemotherapy. Additionally, research has shown that ferroptosis successfully kills cancer cells, such as breast, stem, and lung cancer cells. Therefore, ferroptosis can be identified as a beneficial therapeutic mechanism for cancer treatment. Although ferroptosis has been introduced as an effective treatment path for cancer, its role, along with its therapeutic inducers, in increasing the therapeutic effect has not been investigated. In this review, we aim to introduce ferroptosis, compare it with other cell deaths known so far, and explain its role in cancer treatment. We believe that ferroptosis can be widely used to overcome cancer cells.

Unraveling the triad of hypoxia, cancer cell stemness, and drug resistance

In the domain of addressing cancer resistance, challenges such as limited effectiveness and treatment resistance remain persistent. Hypoxia is a key feature of solid tumors and is strongly associated with poor prognosis in cancer patients. Another significant portion of the development of acquired drug resistance is attributed to tumor stemness. Cancer stem cells (CSCs), a small tumor cell subset with self-renewal and proliferative abilities, are crucial for tumor initiation, metastasis, and intra-tumoral heterogeneity. Studies have shown a significant association between hypoxia and CSCs in the context of tumor resistance. Recent studies reveal a strong link between hypoxia and tumor stemness, which together promote tumor survival and progression during treatment. This review elucidates the interplay between hypoxia and CSCs, as well as their correlation with resistance to therapeutic drugs. Targeting pivotal genes associated with hypoxia and stemness holds promise for the development of novel therapeutics to combat tumor resistance.

Cancer stem cells and tumor-associated macrophages as mates in tumor progression: mechanisms of crosstalk and advanced bioinformatic tools to dissect their phenotypes and interaction

Cancer stem cells (CSCs) are a small subset within the tumor mass significantly contributing to cancer progression through dysregulation of various oncogenic pathways, driving tumor growth, chemoresistance and metastasis formation. The aggressive behavior of CSCs is guided by several intracellular signaling pathways such as WNT, NF-kappa-B, NOTCH, Hedgehog, JAK-STAT, PI3K/AKT1/MTOR, TGF/SMAD, PPAR and MAPK kinases, as well as extracellular vesicles such as exosomes, and extracellular signaling molecules such as cytokines, chemokines, pro-angiogenetic and growth factors, which finely regulate CSC phenotype. In this scenario, tumor microenvironment (TME) is a key player in the establishment of a permissive tumor niche, where CSCs engage in intricate communications with diverse immune cells. The "oncogenic" immune cells are mainly represented by B and T lymphocytes, NK cells, and dendritic cells. Among immune cells, macrophages exhibit a more plastic and adaptable phenotype due to their different subpopulations, which are characterized by both immunosuppressive and inflammatory phenotypes. Specifically, tumor-associated macrophages (TAMs) create an immunosuppressive milieu through the production of a plethora of paracrine factors (IL-6, IL-12, TNF-alpha, TGF-beta, CCL1, CCL18) promoting the acquisition by CSCs of a stem-like, invasive and metastatic phenotype. TAMs have demonstrated the ability to communicate with CSCs via direct ligand/receptor (such as CD90/CD11b, LSECtin/BTN3A3, EPHA4/Ephrin) interaction. On the other hand, CSCs exhibited their capacity to influence immune cells, creating a favorable microenvironment for cancer progression. Interestingly, the bidirectional influence of CSCs and TME leads to an epigenetic reprogramming which sustains malignant transformation. Nowadays, the integration of biological and computational data obtained by cutting-edge technologies (single-cell RNA sequencing, spatial transcriptomics, trajectory analysis) has significantly improved the comprehension of the biunivocal multicellular dialogue, providing a comprehensive view of the heterogeneity and dynamics of CSCs, and uncovering alternative mechanisms of immune evasion and therapeutic resistance. Moreover, the combination of biology and computational data will lead to the development of innovative target therapies dampening CSC-TME interaction. Here, we aim to elucidate the most recent insights on CSCs biology and their complex interactions with TME immune cells, specifically TAMs, tracing an exhaustive scenario from the primary tumor to metastasis formation.

Cytoglobin attenuates melanoma malignancy but protects melanoma cells from ferroptosis

Cutaneous malignant melanoma is the most aggressive and the deadliest form of skin cancer. There are two types of limitations which universally exist in current melanoma therapy: Adverse effects and reduced efficiency. Cytoglobin (CYGB), an iron hexacoordinated globin, is highly enriched in melanocytes and frequently epigenetically silenced during melanoma genesis. The present study aimed to explore its potential role as a biomarker for ferroptosis treatment. It was observed that B16F10 and A375 melanoma cells with loss of CYGB expression were highly sensitive to ferroptosis inducers RSL3 and erastin, whereas G361 melanoma cells with highly enriched CYGB were resistant to RSL3 or erastin. Ectopically overexpressed CYGB rendered B16F10 and A375 cells resistant to RSL3 or erastin, accompanied by decreased proliferation and epithelial‑mesenchymal transition (EMT). By contrast, knockdown of CYGB expression made G361 cells sensitive to ferroptosis induction but induced proliferation and EMT progression of G361 cells. Mechanistically, CYGB‑induced resistance of melanoma cells to ferroptosis may have been associated, in part, with i) Suppression of EMT; ii) upregulation of glutathione peroxidase 4 expression; iii) decrease of labile iron pool. In vivo study also demonstrated that CYGB overexpression rendered xenograft melanoma much more resist to RSL3 treatment. Based on these findings, CYGB is a potential therapeutic biomarker to screen the melanoma patients who are most likely benefit from ferroptosis treatment.

Integrated analysis of ferroptosis and stemness based on single-cell and bulk RNA-sequencing data provide insights into the prognosis and treatment of esophageal carcinoma

BACKGROUND

Cancer stem cells (CSCs) play a significant role in the recurrence and drug resistance of esophageal carcinoma (ESCA). Ferroptosis is a promising anticancer therapeutic strategy that effectively targets CSCs exhibiting high tumorigenicity and treatment resistance. However, there is a lack of research on the combined role of ferroptosis-related genes (FRGs) and stemness signature in the prognosis of ESCA.

METHODS

The cellular compositions were characterized using single-cell RNA sequencing (scRNA-seq) data from 18 untreated ESCA samples. 50 ferroptosis-related stemness genes (FRSGs) were identified by integrating FRGs with stemness-related genes (SRGs), and then the cells were grouped by AUCell analysis. Next, functional enrichment, intercellular communication, and trajectory analyses were performed to characterize the different groups of cells. Subsequently, the stem-ferr-index was calculated using machine learning algorithms based on the expression profiles of the identified risk genes. Additionally, therapeutic drugs were predicted by analyzing the GDSC2 database. Finally, the expression and functional roles of the identified marker genes were validated through in vitro experiments.

RESULTS

The analysis of scRNA-seq data demonstrates the diversity and cellular heterogeneity of ESCA. Then, we identified 50 FRSGs and classified cells into high or low ferroptosis score stemness cells accordingly. Functional enrichment analysis conducted on the differentially up-regulated genes between these groups revealed predominant enrichment in pathways associated with intercellular communication and cell differentiation. Subsequently, we identified 9 risk genes and developed a prognostic signature, termed stem_ferr_index, based on these identified risk genes. We found that the stem-ferr-index was correlated with the clinical characteristics of patients, and patients with high stem-ferr-index had poor prognosis. Furthermore, we identified four drugs (Navitoclax, Foretinib, Axitinib, and Talazoparib) with potential efficacy targeting patients with a high stem_ferr_index. Additionally, we delineated two marker genes (STMN1 and SLC2A1). Particularly noteworthy, SLC2A1 exhibited elevated expression levels in ESCA tissues and cells. We provided evidence suggesting that SLC2A1 could influence the migration, invasion, and stemness of ESCA cells, and it was associated with sensitivity to Foretinib.

CONCLUSION

This study constructed a novel ferroptosis-related stemness signature, identified two marker genes for ESCA, and provided valuable insights for developing more effective therapeutic targets targeting ESCA CSCs in the future.

Decoding secret role of mesenchymal stem cells in regulating cancer stem cells and drug resistance

Drug resistance caused by the efflux of chemotherapeutic drugs is one of the most challenging obstacles to successful cancer therapy. Several efflux transporters have been identified since the discovery of the P-gp/ABCB1 transporter in 1976. Over the last four decades, researchers have focused on developing efflux transporter inhibitors to overcome drug resistance. However, even with the third-generation inhibitors available, we are still far from effectively inhibiting the efflux transporters. Additionally, Cancer stem cells (CSCs) pose another significant challenge, contributing to cancer recurrence even after successful treatment. The ability of CSCs to enter dormancy and evade detection makes them almost invulnerable to chemotherapeutic drug treatment. In this review, we discuss how Mesenchymal stem cells (MSCs), one of the key components of the Tumor Microenvironment (TME), regulate both the CSCs and efflux transporters. We propose a new approach focusing on MSCs, which can be crucial to successfully address CSCs and efflux transporters.

Regulating ferroptosis by non-coding RNAs in hepatocellular carcinoma

Ferroptosis, a unique type of regulated cell death plays a vital role in inhibiting tumour malignancy and has presented new opportunities for treatment of therapy in hepatocellular carcinoma. Accumulating studies indicate that epigenetic modifications by non-coding RNAs, including microRNAs, long noncoding RNAs, and circular RNAs, can determine cancer cell vulnerability to ferroptosis in HCC. The present review first summarize the updated core molecular mechanisms of ferroptosis. We then provide a concised overview of epigenetic modification of ferroptosis in HCC. Finally, we review the recent progress in understanding of the ncRNA-mediated regulated mechanisms on ferroptosis in HCC. The review will promote our understanding of the ncRNA-mediated epigenetic regulatory mechanisms modulating ferroptosis in malignancy of HCC, highlighting a novel strategies for treatment of HCC through targeting ncRNA-ferroptosis axis.

Hypoxia-induced BAP1 enhances erastin-induced ferroptosis in nasopharyngeal carcinoma by stabilizing H2A

BACKGROUND

Hypoxia plays an important role in the chemotherapy resistance of nasopharyngeal carcinoma (NPC). Ferroptosis is a newly discovered form of programmed cell death and ferroptosis inducers showed promising therapeutic effects in some cancers. However, the sensibility of NPC cells to ferroptosis under the hypoxic microenvironment is still unclear, and this study was designed to clarify it.

METHODS

NPC cells, treated with erastin, were placed in a normoxia or hypoxic environment (5% CO2, 94% N2 and 1% O2) at 37℃for 24 h. After exposed to hypoxia, ferroptosis-associated phenotypes were detected by CCK8, MDA, GSH, lipid ROS and Fe. The gene expression profiles of head and neck squamous cell carcinoma (HNSCC) tissues were downloaded from the TCGA database to screen construction molecule. BAP1 was screened out and its functions on erastin-induced ferroptosis in NPC cells were detected by knockdown of BAP1. Luciferase reporter assay and co-IP experiment were performed to explore the molecular mechanism. Finally, the tumour xenograft model was applied to further verify these results in vivo.

RESULTS

CCK8 assay showed that IC50 of NPC cells treated with erastin under hypoxia was significantly lower than that under normoxia. Hypoxia significantly increased the levels of lipid ROS and MDA, and decreased GSH content induced by erastin. A prognostic risk model for HNSCC with six ferroptosis-related genes was constructed and validated based on TCGA database. BAP1 was significantly up-regulated under hypoxia, and luciferase reporter assay showed that HIF-1α was an upstream transcription regulator of BAP1. Knockdown of BAP1 in NPC cells significantly increased the IC50 value of erastin under hypoxia and significantly ameliorated erastin-induced ferroptosis under hypoxia in aspect of lipid ROS, MDA content and GSH. Co-IP results showed that BAP1 mediated deubiquitination of H2A and decreased SLC7A11 expression. Finally, knockdown of BAP1 reduced sensitivity to erastin-induced ferroptosis in a tumour xenograft model. And the level of H2A was significantly decreased in xenograft tumors of BAP1 knockdown cells.

CONCLUSION

Hypoxia-induced BAP1 enhances erastin-induced ferroptosis in NPC by stabilizing H2A. Ferroptosis inducers targeting BAP1 may be an effective way to improve chemotherapy resistance in NPC, especially in the hypoxic microenvironment.

The Dual Role of NRF2 in Colorectal Cancer: Targeting NRF2 as a Potential Therapeutic Approach

Colorectal cancer (CRC), as the third most common bisexual cancer worldwide, requires urgent research on its underlying mechanisms and intervention methods. NRF2 is an important transcription factor involved in the regulation of redox homeostasis, protein degradation, DNA repair, and other cancer processes, playing an important role in cancer. In recent years, the complex role of NRF2 in CRC has been continuously revealed: on the one hand, it exhibits a chemopreventive effect on cancer by protecting normal cells from oxidative stress, and on the other hand, it also exhibits a protective effect on malignant cells. Therefore, this article explores the dual role of NRF2 and its related signaling pathways in CRC, including their chemical protective properties and promoting effects in the occurrence, development, metastasis, and chemotherapy resistance of CRC. In addition, this article focuses on exploring the regulation of NRF2 in CRC ferroptosis, as well as NRF2 drug modulators (activators and inhibitors) targeting CRC, including natural products, compounds, and traditional Chinese medicine formulations.

Epigenetic modification of ferroptosis by non-coding RNAs in cancer drug resistance

The development of drug resistance remains a major challenge in cancer treatment. Ferroptosis, a unique type of regulated cell death, plays a pivotal role in inhibiting tumour growth, presenting new opportunities in treating chemotherapeutic resistance. Accumulating studies indicate that epigenetic modifications by non-coding RNAs (ncRNA) can determine cancer cell vulnerability to ferroptosis. In this review, we first summarize the role of chemotherapeutic resistance in cancer growth/development. Then, we summarize the core molecular mechanisms of ferroptosis, its upstream epigenetic regulation, and its downstream effects on chemotherapeutic resistance. Finally, we review recent advances in understanding how ncRNAs regulate ferroptosis and from such modulate chemotherapeutic resistance. This review aims to enhance general understanding of the ncRNA-mediated epigenetic regulatory mechanisms which modulate ferroptosis, highlighting the ncRNA-ferroptosis axis as a key druggable target in overcoming chemotherapeutic resistance.

FXN targeting induces cell death in ovarian cancer stem-like cells through PRDX3-Mediated oxidative stress

Ovarian cancer stem cells (OCSCs) significantly impact the prognosis, chemoresistance, and treatment outcomes in OC. While ferroptosis has been proven effective against OCSCs, the intricate relationship between ferroptosis and OCSCs remains incompletely understood. Here, we enriched ovarian cancer stem-like cells (OCSLCs) through mammosphere culture, as an OCSC model. OCSLCs displayed heightened ferroptosis susceptibility, correlating with elevated FXN levels compared to non-stem OC cells. FXN has recently emerged as a potential regulator in ferroptosis. FXN knockdown diminished stemness marker nanog, sphere-forming ability, increased reactive oxygen species (ROS) generation, and attenuated OCSLCs viability. FXN overexpression exacerbated ferroptosis resistance and reduced RSL3-induced cell death. FXN knockdown impeded OCSLC xenograft tumor growth and exacerbated the degeneration of peroxiredoxin 3 (PRDX3), a mitochondrial antioxidant protein participates in oxidative stress. Thus, elevated FXN in OCSLCs suppresses ROS accumulation, fostering ferroptosis resistance, and regulates the antioxidant protein PRDX3. FXN emerges as a potential therapeutic target for OC.

Ferroptosis in the adjuvant treatment of lung cancer-the potential of selected botanical drugs and isolated metabolites

Ferroptosis represents a distinct form of cell death that is not associated with necrosis, autophagy, apoptosis, or pyroptosis. It is characterised by intracellular iron-dependent lipid peroxidation. The current literature indicates that a number of botanical drugs and isolated metabolites can modulate ferroptosis, thereby exerting inhibitory effects on lung cancer cells or animal models. The aim of this review is to elucidate the mechanisms through which botanical drugs and isolated metabolites regulate ferroptosis in the context of lung cancer, thereby providing potential insights into lung cancer treatment. It is crucial to highlight that these preclinical findings should not be interpreted as evidence that these treatments can be immediately translated into clinical applications. In the future, we will continue to study the pharmacology, pharmacokinetics and toxicology of these drugs, as well as evaluating their efficacy and safety in clinical trials, with the aim of providing new approaches to the development of new agents for the treatment of lung cancer.

Polyunsaturated Fatty Acids in Quinoa Induce Ferroptosis of Colon Cancer by Suppressing Stemness

Polyunsaturated fatty acids (PUFAs) are essential nutrients for the human body, playing crucial roles in reducing blood lipids, anti-inflammatory responses, and anticancer effect. Quinoa is a nutritionally sound food source, rich in PUFAs. This study investigates the role of quinoa polyunsaturated fatty acids (QPAs) on quelling drug resistance in colorectal cancer. The results reveal that QPA downregulates the expression of drug-resistant proteins P-gp, MRP1, and BCRP, thereby enhancing the sensitivity of colorectal cancer drug-resistant cells to the chemotherapy drug. QPA also inhibits the stemness of drug-resistant colorectal cancer cells by reducing the expression of the stemness marker CD44. Consequently, it suppresses the downstream protein SLC7A11 and leads to ferroptosis. Additionally, QPA makes the expression of ferritin lower and increases the concentration of free iron ions within cells, leading to ferroptosis. Overall, QPA has the dual-function reversing drug resistance in colorectal cancer by simultaneously inhibiting stemness and inducing ferroptosis. This study provides a new option for chemotherapy sensitizers and establishes a theoretical foundation for the development and utilization of quinoa.

SBFI26 induces triple-negative breast cancer cells ferroptosis via lipid peroxidation

SBFI26, an inhibitor of FABP5, has been shown to suppress the proliferation and metastasis of tumour cells. However, the underlying mechanism by which SBFI26 induces ferroptosis in breast cancer cells remains largely unknown. Three breast cancer cell lines were treated with SBFI26 and CCK-8 assessed cytotoxicity. Transcriptome was performed on the Illumina platform and verified by qPCR. Western blot evaluated protein levels. Malondialdehyde (MDA), total superoxide dismutase (T-SOD), Fe, glutathione (GSH) and oxidized glutathione (GSSG) were measured. SBFI26 induced cell death time- and dose-dependent, with a more significant inhibitory effect on MDA-MB-231 cells. Fer-1, GSH and Vitamin C attenuated the effects but not erastin. RNA-Seq analysis revealed that SBFI26 treatment significantly enriched differentially expressed genes related to ferroptosis. Furthermore, SBFI26 increased intracellular MDA, iron ion, and GSSG levels while decreasing T-SOD, total glutathione (T-GSH), and GSH levels.SBFI26 dose-dependently up-regulates the expression of HMOX1 and ALOX12 at both gene and protein levels, promoting ferroptosis. Similarly, it significantly increases the expression of SAT1, ALOX5, ALOX15, ALOXE3 and CHAC1 that, promoting ferroptosis while downregulating the NFE2L2 gene and protein that inhibit ferroptosis. SBFI26 leads to cellular accumulation of fatty acids, which triggers excess ferrous ions and subsequent lipid peroxidation for inducing ferroptosis.

The opposite role of lactate dehydrogenase a (LDHA) in cervical cancer under energy stress conditions

Due to insufficient and defective vascularization, the tumor microenvironment is often nutrient-depleted. LDHA has been demonstrated to play a tumor-promoting role by facilitating the glycolytic process. However, whether and how LDHA regulates cell survival in the nutrient-deficient tumor microenvironment is still unclear. Here, we sought to investigate the role and mechanism of LDHA in regulating cell survival and proliferation under energy stress conditions. Our results showed that the aerobic glycolysis levels, cell survival and proliferation of cervical cancer cells decreased significantly after inhibition of LDHA under normal culture condition while LDHA deficiency greatly inhibited glucose starvation-induced ferroptosis and promoted cell proliferation and tumor formation under energy stress conditions. Mechanistic studies suggested that glucose metabolism shifted from aerobic glycolysis to mitochondrial OXPHOS under energy stress conditions and LDHA knockdown increased accumulation of pyruvate in the cytosol, which entered the mitochondria and upregulated the level of oxaloacetate by phosphoenolpyruvate carboxylase (PC). Importantly, the increase in oxaloacetate production after absence of LDHA remarkably activated AMP-activated protein kinase (AMPK), which increased mitochondrial biogenesis and mitophagy, promoted mitochondrial homeostasis, thereby decreasing ROS level. Moreover, repression of lipogenesis by activation of AMPK led to elevated levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which effectively resisted ROS-induced cell ferroptosis and enhanced cell survival under energy stress conditions. These results suggested that LDHA played an opposing role in survival and proliferation of cervical cancer cells under energy stress conditions, and inhibition of LDHA may not be a suitable treatment strategy for cervical cancer.

Identification of clinical prognostic factors and analysis of ferroptosis-related gene signatures in the bladder cancer immune microenvironment

BACKGROUND

Bladder cancer (BLCA) is a prevalent malignancy affecting the urinary system and poses a significant burden in terms of both incidence and mortality rates on a global scale. Among all BLCA cases, non-muscle invasive bladder cancer constitutes approximately 75% of the total. In recent years, the concept of ferroptosis, an iron-dependent form of regulated cell death marked by the accumulation of lipid peroxides, has captured the attention of researchers worldwide. Nevertheless, the precise involvement of ferroptosis-related genes (FRGs) in the anti-BLCA response remains inadequately elucidated.

METHODS

The integration of BLCA samples from the TCGA and GEO datasets facilitated the quantitative evaluation of FRGs, offering potential insights into their predictive capabilities. Leveraging the wealth of information encompassing mRNAsi, gene mutations, CNV, TMB, and clinical features within these datasets further enriched the analysis, augmenting its robustness and reliability. Through the utilization of Lasso regression, a prediction model was developed, enabling accurate prognostic assessments within the context of BLCA. Additionally, co-expression analysis shed light on the complex relationship between gene expression patterns and FRGs, unraveling their functional relevance and potential implications in BLCA.

RESULTS

FRGs exhibited increased expression levels in the high-risk cohort of BLCA patients, even in the absence of other clinical indicators, suggesting their potential as prognostic markers. GSEA revealed enrichment of immunological and tumor-related pathways specifically in the high-risk group. Furthermore, notable differences were observed in immune function and m6a gene expression between the low- and high-risk groups. Several genes, including MYBPH, SOST, SPRR2A, and CRNN, were found to potentially participate in the oncogenic processes underlying BLCA. Additionally, CYP4F8, PDZD3, CRTAC1, and LRTM1 were identified as potential tumor suppressor genes. Significant discrepancies in immunological function and m6a gene expression were observed between the two risk groups, further highlighting the distinct molecular characteristics associated with different prognostic outcomes. Notably, strong correlations were observed among the prognostic model, CNVs, SNPs, and drug sensitivity profiles.

CONCLUSIONS

FRGs are associated with the onset and progression of BLCA. A FRGs signature offers a viable alternative to predict BLCA, and these FRGs show a prospective research area for BLCA targeted treatment in the future.

Timosaponin AIII induces lipid peroxidation and ferroptosis by enhancing Rab7-mediated lipophagy in colorectal cancer cells

BACKGROUND

Colorectal cancer (CRC) is a common digestive system malignancy, and despite significant therapeutic advancements, more effective treatments are needed. Timosaponin AIII (TA-III), a major steroidal saponin derived from Anemarrhena asphodeloides Bge, is a potential anticancer agent. Ferroptosis plays an important role in cancer treatment.

PURPOSE

To investigate the molecular mechanism of TA-III as a novel ferroptosis inducer in suppressing CRC through lipophagy. Ferroptosis, an autophagy-dependent mode of cell death, has been implicated in CRC.

METHODS

CRC cells were treated with TA-III, and lipophagy levels were evaluated via BODIPY493/503 staining and western blotting. Autophagy turnover was tracked using GFP-RFP-LC3B. Lipid peroxidation was quantified using an malondialdehyde kit and C11-BODIPY flow assay. Mitochondrial morphology was observed using transmission electron microscopy. GC-MS/MS was used to detect lipid metabolism changes. The role of ras related protein Rab 7a (Rab7) was assessed by western blotting and glutathione S-transferase pull-down assays. In vivo, the anticancer efficacy of TA-III was tested using a xenograft model.

RESULTS

RNA-seq analysis unveiled the potential of TA-III as an anticancer agent through ferroptosis. In vivo experiments revealed how TA-III treatment triggered degradation of lipid droplets in CRC cells, resulting in an accumulation of FFAs, heightened unsaturated free fatty acids, and increased lipid peroxidation. These events ultimately lead to mitochondrial shrinkage and downregulation of ferroptosis markers (FSP1 and GPX4). Intriguingly, the Rab7 protein emerged as a crucial bridge between lipophagy and ferroptosis, underlining its significance in the anticancer mechanism of TA-III. Moreover, TA-III treatment in a xenograft tumour model substantially reduced tumour volume via ferroptosis, underscoring its therapeutic efficacy.

CONLUSION

Our study is the first to establish that TA-III triggers lipophagy in CRC cells via the Rab7 gene, subsequently promoting ferroptosis. This suggests its potential use as an antitumour agent.

Artesunate Inhibits the Growth of Insulinoma Cells via SLC7A11/ GPX4-mediated Ferroptosis

BACKGROUND

Artesunate (ART) has been recognized to induce ferroptosis in various tumor phenotypes, including neuroendocrine tumors. We aimed to investigate the effects of ART on insulinoma and the underlying mechanisms by focusing on the process of ferroptosis.

METHODS

The CCK8 and colony formation assays were conducted to assess the effectiveness of ART. Lipid peroxidation, glutathione, and intracellular iron content were determined to validate the process of ferroptosis, while ferrostatin-1 (Fer-1) was employed as the inhibitor of ferroptosis. Subcutaneous tumor models were established and treated with ART. The ferroptosis-associated proteins were determined by western blot and immunohistochemistry assays. Pathological structures of the liver were examined by hematoxylin-eosin staining.

RESULTS

ART suppressed the growth of insulinoma both in vitro and in vivo. Insulinoma cells treated by ART revealed signs of ferroptosis, including increased lipid peroxidation, diminished glutathione levels, and ascending intracellular iron. Notably, ART-treated insulinoma cells exhibited a decline in the expressions of catalytic component solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4). These alterations were negated by Fer-1. Moreover, no hepatotoxicity was observed upon the therapeutic dose of ART.

CONCLUSION

Artesunate might regulate ferroptosis of insulinoma cells through the SLC7A11/GPX4 pathway.

Engineering Versatile Nanomedicines for Ultrasonic Tumor Immunotherapy

Due to the specific advantages of ultrasound (US) in therapeutic disease treatments, the unique therapeutic US technology has emerged. In addition to featuring a low-invasive targeted cancer-cell killing effect, the therapeutic US technology has been demonstrated to modulate the tumor immune landscape, amplify the therapeutic effect of other antitumor therapies, and induce immunosensitization of tumors to immunotherapy, shedding new light on the cancer treatment. Tremendous advances in nanotechnology are also expected to bring unprecedented benefits to enhancing the antitumor efficiency and immunological effects of therapeutic US, as well as therapeutic US-derived bimodal and multimodal synergistic therapies. This comprehensive review summarizes the immunological effects induced by different therapeutic US technologies, including ultrasound-mediated micro-/nanobubble destruction (UTMD/UTND), sonodynamic therapy (SDT), and focused ultrasound (FUS), as well as the main underlying mechanisms involved. It is also discussed that the recent research progress of engineering intelligent nanoplatform in improving the antitumor efficiency of therapeutic US technologies. Finally, focusing on clinical translation, the key issues and challenges currently faced are summarized, and the prospects for promoting the clinical translation of these emerging nanomaterials and ultrasonic immunotherapy in the future are proposed.

Moving beyond cisplatin resistance: mechanisms, challenges, and prospects for overcoming recurrence in clinical cancer therapy

Cisplatin, a classical platinum-based chemotherapy agent, has been a frontline treatment for various cancers for decades. However, its effectiveness has been hindered by the development of resistance, leading to cancer relapse. Addressing this challenge is crucial for both clinical practice and research. Hence, the imperative to unravel the intricate mechanisms underpinning cisplatin resistance and to uncover novel strategies to overcome this barrier holds immense significance. Within this review, we summarized the classification of platinum agents, highlighting their roles in therapeutic landscapes. We discussed the diverse mechanisms behind cisplatin resistance, including diminished intracellular cisplatin accumulation, intracellular detoxification, DNA repair, autophagy responses, heat shock proteins, tumor microenvironment, cancer stem cells, epigenetic regulation, ferroptosis resistance, and metabolic reprogramming. Drawing from this comprehensive understanding, we offered a series of prospective solutions to surmount cisplatin resistance and consequently mitigate the specter of disease recurrence within the realm of clinical cancer therapy.

Mechanisms and applications of ferroptosis-associated regulators in cancer therapy and drug resistance

Iron is an essential element for almost all living things. Both iron excess and iron deficiency can damage the body's health, but the body has developed complex mechanisms to regulate iron balance. The imbalance of iron homeostasis and lipid peroxidation are important features of ferroptosis. In this review, we summarize the latest regulatory mechanisms of ferroptosis, the roles of relevant regulators that target ferroptosis for cancer therapy, and their relationship to drug resistance. In conclusion, targeting ferroptosis is an important strategy for cancer therapy.

Targeting GDP-Dissociation Inhibitor Beta (GDI2) with a Benzo[a]quinolizidine Library to Induce Paraptosis for Cancer Therapy

Inducing paraptosis, a nonapoptotic form of cell death, has great therapeutic potential in cancer therapy, especially for drug-resistant tumors. However, the specific molecular target(s) that trigger paraptosis have not yet been deciphered yet. Herein, by using activity-based protein profiling, we identified the GDP-dissociation inhibitor beta (GDI2) as a manipulable target for inducing paraptosis and uncovered benzo[a]quinolizidine BQZ-485 as a potent inhibitor of GDI2 through the interaction with Tyr245. Comprehensive target validation revealed that BQZ-485 disrupts the intrinsic GDI2-Rab1A interaction, thereby abolishing vesicular transport from the endoplasmic reticulum (ER) to the Golgi apparatus and initiating subsequent paraptosis events including ER dilation and fusion, ER stress, the unfolded protein response, and cytoplasmic vacuolization. Based on the structure of BQZ-485, we created a small benzo[a]quinolizidine library by click chemistry and discovered more potent GDI2 inhibitors using a NanoLuc-based screening platform. Leveraging the engagement of BQZ-485 with GDI2, we developed a selective GDI2 degrader. The optimized inhibitor (+)-37 and degrader 21 described in this study exhibited excellent in vivo antitumor activity in two GDI2-overexpressing pancreatic xenograft models, including an AsPc-1 solid tumor model and a transplanted human PDAC tumor model. Altogether, our findings provide a promising strategy for targeting GDI2 for paraptosis in the treatment of pancreatic cancers, and these lead compounds could be further optimized to be effective chemotherapeutics.

AKT1 participates in ferroptosis vulnerability by driving autophagic degradation of FTH1 in cisplatin-resistant ovarian cancer

Resistance to cisplatin (DDP)-based chemotherapy is an important reason for the failure of ovarian cancer treatment. However, tumor cells resistant to chemotherapy may expose vulnerability to other cell death pathways. Here, we found that DDP-resistant ovarian cancer cells are more susceptible to erastin-induced ferroptosis. It should be noted that this vulnerability does not depend on the weakening of classical ferroptosis defense proteins, but is caused by the reduction of ferritin heavy chain (FTH1). DDP-resistant ovarian cancer cells maintain a high level of autophagy to escape the pressure of chemotherapy, which ultimately leads to increased autophagic degradation of FTH1. We further revealed that the loss of AKT1 was the reason for the increased autophagy level of DDP-resistant ovarian cancer cells. Our study provides new insights into reversing DDP resistance in ovarian cancer by targeting ferroptosis pathway, and AKT1 may be a molecular marker of susceptibility to ferroptosis.

Isoorientin reverses lung cancer drug resistance by promoting ferroptosis via the SIRT6/Nrf2/GPX4 signaling pathway

Cisplatin, or DDP, is a highly successful and well-known chemotherapy drug used to treat cancer. Acquired resistance to chemotherapy is a major clinical concern, yet the mechanisms of this resistance are still unknown. Ferroptosis is a type of cell death distinct from other forms, fueled by a buildup of iron-associated lipid reactive oxygen species (ROS). Gaining insight into the process of ferroptosis could lead to novel treatments for overcoming cancer resistance. In this study, the combination of isoorientin (IO) and DDP treatment resulted in a significant decrease in the viability of drug-resistant cells, a substantial increase in intracellular iron, malondialdehyde (MDA) and ROS concentrations, a notable decrease in glutathione concentration, and the occurrence of ferroptosis in cells, as revealed by in vitro and in vivo experiments. Additionally, there was a decrease in the expression of nuclear factor-erythroid factor 2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), and sirtuin 6 (SIRT6) proteins, and an increase in cellular ferroptosis. Isoorientin acts as a mediator to regulate cellular ferroptosis and reverse drug resistance in lung cancer cells by controlling the SIRT6/Nrf2/GPX4 signaling pathway. The findings of this study suggest that IO can promote ferroptosis and reverse drug resistance in lung cancer through the SIRT6/Nrf2/GPX4 signaling pathway, thus offering a theoretical basis for its potential clinical application.

Regulation of iron metabolism and ferroptosis in cancer stem cells

The ability of cancer stem cells (CSCs) to self-renew, differentiate, and generate new tumors is a significant contributor to drug resistance, relapse, and metastasis. Therefore, the targeting of CSCs for treatment is particularly important. Recent studies have demonstrated that CSCs are more susceptible to ferroptosis than non-CSCs, indicating that this could be an effective strategy for treating tumors. Ferroptosis is a type of programmed cell death that results from the accumulation of lipid peroxides caused by intracellular iron-mediated processes. CSCs exhibit different molecular characteristics related to iron and lipid metabolism. This study reviews the alterations in iron metabolism, lipid peroxidation, and lipid peroxide scavenging in CSCs, their impact on ferroptosis, and the regulatory mechanisms underlying iron metabolism and ferroptosis. Potential treatment strategies and novel compounds targeting CSC by inducing ferroptosis are also discussed.

Targeting the tumor microenvironment: Potential strategy for cancer therapeutics

Cellular and stromal components including tumor cells, immune cells, mesenchymal cells, cancer-linked fibroblasts, and extracellular matrix, constituent tumor microenvironment (TME). TME plays a crucial role in reprogramming tumor initiation, uncontrolled proliferation, invasion and metastasis as well as response to therapeutic modalities. In recent years targeting the TME has developed as a potential strategy for treatment of cancer because of its life-threatening functions in restricting tumor development and modulating responses to standard-of-care medicines. Cold atmospheric plasma, oncolytic viral therapy, bacterial therapy, nano-vaccine, and repurposed pharmaceuticals with combination therapy, antiangiogenic drugs, and immunotherapies are among the most effective therapies directed by TME that have either been clinically authorized or are currently being studied. This article discusses above-mentioned therapies in light of targeting TME. We also cover problems related to the TME-targeted therapies, as well as future insights and practical uses in this rapidly growing field.

Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

Vitamin D Promotes Ferroptosis in Colorectal Cancer Stem Cells via SLC7A11 Downregulation

Colorectal cancer stem cells (CCSCs) play important roles in the prognosis, chemoresistance, and treatment failure of colorectal cancer (CRC). Ferroptosis is an effective treatment for CCSCs. Vitamin D (VD) reportedly inhibits colon cancer cell proliferation. However, information on the relationship between VD and ferroptosis in CCSCs is not well documented. In this study, we aimed to understand the effect of VD on ferroptosis in CCSCs. To this end, we treated CCSCs with different concentrations of VD and performed spheroid formation assay and transmission electron microscopy and determined cysteine (Cys), glutathione (GSH), and reactive oxygen species (ROS) levels. Furthermore, functional experiments, western blotting, and qRT-PCR were performed to explore the downstream molecular mechanisms of VD in vitro and in vivo. Results showed that VD treatment significantly inhibited the proliferation of CCSCs and reduced the number of tumour spheroids in vitro. Further evaluations showed that the VD-treated CCSCs exhibited significantly higher ROS levels and lower levels of Cys and GSH as well as thickened mitochondrial membranes. Furthermore, the mitochondria in CCSCs were narrowed and ruptured after VD treatment. These results indicated that VD treatment significantly induced ferroptosis in CCSCs. Further exploration showed that SLC7A11 overexpression significantly attenuated VD-induced ferroptosis in vitro and in vivo. Hence, we concluded that VD induces ferroptosis in CCSCs by downregulating SLC7A11 in vitro and in vivo. These results provide new evidence for the therapeutic use of VD in treating CRC and new insights into VD-induced ferroptosis in CCSCs.

Impact of Ferroptosis Inducers on Chronic Radiation-exposed Survivor Glioblastoma Cells

INTRODUCTION

The median survival of patients diagnosed with glioblastoma is very poor, despite efforts to improve the therapeutic effects of surgery, followed by treatment with temozolomide (TMZ) and ionizing radiation (IR). The utilization of TMZ or IR survivor cell models has enhanced the understanding of glioblastoma biology and the development of novel therapeutic strategies. In this present study, naïve U373 and clinically relevant U373 IRsurvivor (Surv) cells were used, as the IR-Surv cell model mimics the chronic long-term exposure to standardized radiotherapy for patients with glioblastoma in the clinic. As the role of ferroptosis in the IR survivor cell model has not previously been reported, we aimed to clarify its involvement in the clinically relevant IR-Surv glioblastoma model.

METHODS

Transcriptomic alterations of ferroptosis-related genes were studied on naïve U373 and IR-Surv cell populations. To determine the effects of glutathione peroxidase inhibitors, ferroptosis-inducing agent 56 (FIN56) and Ras synthetic lethal 3 (RSL3), on the cells, several properties were assessed, including colony formation, cell viability and lipid peroxidation.

RESULTS

Results from the transcriptomic analysis identified ferroptosis as a critical mechanism after radiation exposure in glioblastoma. Our findings also identified the role of ferroptosis inducers (FINs) in IR-survivor cells and suggested using FINs to treat glioblastoma.

CONCLUSION

FINs serve an important role in radioresistant cells; thus, the results of the present study may contribute to improving survival in patients with glioblastoma.

FAK downregulation suppresses stem-like properties and migration of human colorectal cancer cells

Focal adhesion kinase (FAK) is a cytoplasmic protein tyrosine kinase, which is overexpressed in colorectal cancer cells. FAK could be activated by phosphorylation to participate in the transduction of multiple signaling pathways and self-renewal of cancer stem cells. Whether the downregulation of FAK inhibits the metastasis in colorectal cancer through the weakening of stem cell-like properties and its mechanisms has yet to be established. CD44, CD133, c-Myc, Nanog, and OCT4 were known to mark colorectal cancer stem cell properties. In this study, AKT inhibitor (MK-2206 2HCl) or FAK inhibitor (PF-562271) decreased the expression of stem cell markers (Nanog, OCT4, CD133, CD44, c-Myc) and spheroid formation in colorectal cancer. Moreover, FAK and AKT protein was shown to interact verified by co-immunoprecipitation. Furthermore, downregulation of FAK, transfected Lenti-FAK-EGFP-miR to colorectal cancer cells, reduced p-AKT but not AKT and decreased the expression of stem cell markers and spheroid formation in colorectal cancer. In conclusion, we demonstrated that downregulation of FAK inhibited stem cell-like properties and migration of colorectal cancer cells partly due to altered modulation of AKT phosphorylation by FAK.

Relationships of ferroptosis-related genes with the pathogenesis in polycystic ovary syndrome

Background

Numerous studies have suggested that ferroptosis plays a significant role in the development of polycystic ovary syndrome (PCOS), but the mechanism remains unclear.

Methods

In this study, we explored the role of ferroptosis-related genes in the pathogenesis of PCOS using a comprehensive bioinformatics method. First, we downloaded several Gene Expression Omnibus (GEO) datasets and combined them into a meta-GEO dataset. Differential expression analysis was performed to screen for significant ferroptosis-related genes between the normal and PCOS samples. The least absolute shrinkage selection operator regression and support vector machine-recursive feature elimination were used to select the best signs to construct a PCOS diagnostic model. Receiver operating characteristic curve analysis and decision curve analysis were applied to test the performance of the model. Finally, a ceRNA network-related ferroptosis gene was constructed.

Results

Five genes, namely, NOX1, ACVR1B, PHF21A, FTL, and GALNT14, were identified from 10 differentially expressed ferroptosis-related genes to construct a PCOS diagnostic model. Finally, a ceRNA network including 117 lncRNAs, 67 miRNAs, and five ferroptosis-related genes was constructed.

Conclusion

Our study identified five ferroptosis-related genes that may be involved in the pathogenesis of PCOS, which may provide a novel perspective for the clinical diagnosis and treatment of PCOS.

Study of Cytotoxicity and Internalization of Redox-Responsive Iron Oxide Nanoparticles on PC-3 and 4T1 Cancer Cell Lines

Redox-responsive and magnetic nanomaterials are widely used in tumor treatment separately, and while the application of their combined functionalities is perspective, exactly how such synergistic effects can be implemented is still unclear. This report investigates the internalization dynamics of magnetic redox-responsive nanoparticles (MNP-SS) and their cytotoxicity toward PC-3 and 4T1 cell lines. It is shown that MNP-SS synthesized by covalent grafting of polyethylene glycol (PEG) on the magnetic nanoparticle (MNP) surface via SS-bonds lose their colloidal stability and aggregate fully in a solution containing DTT, and partially in conditioned media, whereas the PEGylated MNP (MNP-PEG) without S-S linker control remains stable under the same conditions. Internalized MNP-SS lose the PEG shell more quickly, causing enhanced magnetic core dissolution and thus increased toxicity. This was confirmed by fluorescence microscopy using MNP-SS dual-labeled by Cy3 via labile disulfide, and Cy5 via a rigid linker. The dyes demonstrated a significant difference in fluorescence dynamics and intensity. Additionally, MNP-SS demonstrate quicker cellular uptake compared to MNP-PEG, as confirmed by TEM analysis. The combination of disulfide bonds, leading to faster dissolution of the iron oxide core, and the high-oxidative potential Fe³⁺ ions can synergically enhance oxidative stress in comparison with more stable coating without SS-bonds in the case of MNP-PEG. It decreases the cancer cell viability, especially for the 4T1, which is known for being sensitive to ferroptosis-triggering factors. In this work, we have shown the effect of redox-responsive grafting of the MNP surface as a key factor affecting MNP-internalization rate and dissolution with the release of iron ions inside cancer cells. This kind of synergistic effect is described for the first time and can be used not only in combination with drug delivery, but also in treatment of tumors responsive to ferroptosis.

Insights on Ferroptosis and Colorectal Cancer: Progress and Updates

Patients with advanced-stage or treatment-resistant colorectal cancer (CRC) benefit less from traditional therapies; hence, new therapeutic strategies may help improve the treatment response and prognosis of these patients. Ferroptosis is an iron-dependent type of regulated cell death characterized by the accumulation of lipid reactive oxygen species (ROS), distinct from other types of regulated cell death. CRC cells, especially those with drug-resistant properties, are characterized by high iron levels and ROS. This indicates that the induction of ferroptosis in these cells may become a new therapeutic approach for CRC, particularly for eradicating CRC resistant to traditional therapies. Recent studies have demonstrated the mechanisms and pathways that trigger or inhibit ferroptosis in CRC, and many regulatory molecules and pathways have been identified. Here, we review the current research progress on the mechanism of ferroptosis, new molecules that mediate ferroptosis, including coding and non-coding RNA; novel inducers and inhibitors of ferroptosis, which are mainly small-molecule compounds; and newly designed nanoparticles that increase the sensitivity of cells to ferroptosis. Finally, the gene signatures and clusters that have predictive value on CRC are summarized.

Inhibition of ABCC9 by zinc oxide nanoparticles induces ferroptosis and inhibits progression, attenuates doxorubicin resistance in breast cancer

Background

Zinc oxide nanoparticles (ZONs) are a type of nanomaterial that has presented anti-cancer properties in breast cancer (BC). However, the function of ABCC9 in BC and its correlation with ZONs are still elusive.

Methods

Here, we identified the crucial role of ABCC9 in modulating ferroptosis and doxorubicin (Dox) resistance in BC and the targeted function of ZONs to ABCC9.

Results

The silencing of ABCC9 significantly repressed the viability of BC cells. The knockdown of ABCC9 decreased the numbers of Edu-positive BC cells. Conversely, BC cell apoptosis was increased by the inhibition of ABCC9. Besides, the silencing of ABCC9 reduced the capability of migration and invasion of BC cells. Significantly, tumorigenicity analysis demonstrated that the tumor growth of BC cells was suppressed by the depletion of ABCC9 in the xenograft model of nude mice. Moreover, the treatment of ferroptosis activator erastin repressed cell viability of BC cells and ABCC9 overexpression rescued the repression. Similarly, the numbers of Edu-positive BC cells were inhibited by erastin and the overexpression of ABCC9 reversed the inhibitory effect of erastin. The levels of GSH were decreased and MDA, lipid ROS, and iron levels were increased by the treatment of erastin, while the ABCC9 overexpression could reverse these results in BC cells. Consistently, erastin suppressed the expression of ferroptosis inhibitory factors, including GPX4 and SLC7A11, in BC cells and the overexpression of ABCC9 rescued the expression. The IC50 value of Dox was reduced by the knockdown of ABCC9 in Dox-resistant BC cells (BC/Dox). The numbers of Edu-positive BC/Dox cells were attenuated by the depletion of ABCC9. Meanwhile, the apoptosis of BC/Dox cells was stimulated by the silencing of ABCC9. Furthermore, the treatment of ZONs attenuated Dox resistance of BC cells. ZONs remarkably repressed the expression of ABCC9 in BC/Dox cells. ZONs inhibited the cell viability of BC/Dox cells and the overexpression of ABCC9 reversed the repression. Moreover, the treatment of ZONs reduced GSH levels and enhanced MDA, lipid ROS, and iron levels in erastin-stimulated BC/Dox cells.

Conclusions

In conclusion, we discovered that the inhibition of ABCC9 by zinc oxide nanoparticles induces ferroptosis and attenuates Dox resistance in BC.

Emerging Potential Mechanism and Therapeutic Target of Ferroptosis in PDAC: A Promising Future

Pancreatic cancer (PC) is a devastating malignant tumor of gastrointestinal (GI) tumors characterized by late diagnosis, low treatment success and poor prognosis. The most common pathological type of PC is pancreatic ductal adenocarcinoma (PDAC), which accounts for approximately 95% of PC. PDAC is primarily driven by the Kirsten rat sarcoma virus (KRAS) oncogene. Ferroptosis was originally described as ras-dependent cell death but is now defined as a regulated cell death caused by iron accumulation and lipid peroxidation. Recent studies have revealed that ferroptosis plays an important role in the development and therapeutic response of tumors, especially PDAC. As the non-apoptotic cell death, ferroptosis may minimize the emergence of drug resistance for clinical trials of PDAC. This article reviews what has been learned in recent years about the mechanisms of ferroptosis in PDAC, introduces the association between ferroptosis and the KRAS target, and summarizes several potential strategies that are capable of triggering ferroptosis to suppress PDAC progression.

Therapy-resistant nature of cancer stem cells in view of iron metabolism

Due to increased resistance to standard chemo/radiotherapies and relapse, highly tumorigenic cancer stem cells (CSCs) have been proposed as a promising target for the development of effective cancer treatments. In order to develop innovative cancer therapies that target CSCs, much attention has focused on the iron metabolism of CSCs, which has been considered to contribute to self-renewal of CSCs. Here, we review recent advances in iron metabolism and conventional iron metabolism-targeted cancer therapies, as well as therapy resistance of CSCs and potential treatment options to overcome them, which provide important insights into therapeutic strategies against intractable cancers. Potential treatment options targeting iron homeostasis, including small-molecule inhibitors, nanotechnology platforms, ferroptosis, and 5-ALA-PDT, might be a focus of future research for the development of innovative cancer therapies that tackle CSCs.

Effective prediction of potential ferroptosis critical genes in clinical colorectal cancer

Background

Colon cancer is common worldwide, with high morbidity and poor prognosis. Ferroptosis is a novel form of cell death driven by the accumulation of iron-dependent lipid peroxides, which differs from other programmed cell death mechanisms. Programmed cell death is a cancer hallmark, and ferroptosis is known to participate in various cancers, including colon cancer. Novel ferroptosis markers and targeted colon cancer therapies are urgently needed. To this end, we performed a preliminary exploration of ferroptosis-related genes in colon cancer to enable new treatment strategies.

Methods

Ferroptosis-related genes in colon cancer were obtained by data mining and screening for differentially expressed genes (DEGs) using bioinformatics analysis tools. We normalized the data across four independent datasets and a ferroptosis-specific database. Identified genes were validated by immunohistochemical analysis of pathological and healthy clinical samples.

Results

We identified DEGs in colon cancer that are involved in ferroptosis. Among these, five core genes were found: ELAVL1, GPX2, EPAS1, SLC7A5, and HMGB1. Bioinformatics analyses revealed that the expression of all five genes, except for EPAS1, was higher in tumor tissues than in healthy tissues.

Conclusions

The preliminary exploration of the five core genes revealed that they are differentially expressed in colon cancer, playing an essential role in ferroptosis. This study provides a foundation for subsequent research on ferroptosis in colon cancer.

Identification and Validation of a Novel Ferroptotic Prognostic Genes-Based Signature of Clear Cell Renal Cell Carcinoma

Renal cell carcinoma (RCC), as one of the primary urological malignant neoplasms, shows poor survival, and the leading pathological type of RCC is clear cell RCC (ccRCC). Differing from other cell deaths (such as apoptosis, necroptosis, pyroptosis, and autophagy), ferroptosis is characterized by iron-dependence, polyunsaturated fatty acid oxidization, and lipid peroxide accumulation. We analyzed the ferroptosis database (FerrDb V2), Gene Expression Omnibus database, The Cancer Genome Atlas database, and the ArrayExpress database. Nine genes that were differentially expressed and related to prognosis were involved in the ferroptotic prognostic model via the least absolute shrinkage and selection operator Cox regression analysis, which was established in ccRCC patients from the kidney renal clear cell carcinoma (KIRC) cohort in TCGA database, and validated in ccRCC patients from the E-MTAB-1980 cohort in the ArrayExpress database. The signature could be an independent prognostic factor for ccRCC, and high-risk patients showed worse overall survival. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were utilized to investigate the potential mechanisms. The nine genes in ccRCC cells with erastin or RSL3 treatment were validated to find the crucial gene. The glutaminase 2 (GLS2) gene was upregulated during ferroptosis in ccRCC cells, and cells with GLS2 shRNA displayed lower survival, a lower glutathione level, and a high lipid peroxide level, which illustrated that GLS2 might be a ferroptotic suppressor in ccRCC.

Lessons to cancer from studies of leukemia and hematopoiesis

The starting point to describing the origin and nature of any cancer must be knowledge about how the normal counterpart tissue develops. New principles to the nature of hematopoietic stem cells have arisen in recent years. In particular, hematopoietic stem cells can “choose” a cell lineage directly from a spectrum of the end-cell options, and are, therefore, a heterogeneous population of lineage affiliated/biased cells. These cells remain versatile because the developmental trajectories of hematopoietic stem and progenitor cells are broad. From studies of human acute myeloid leukemia, leukemia is also a hierarchy of maturing or partially maturing cells that are sustained by leukemia stem cells at the apex. This cellular hierarchy model has been extended to a wide variety of human solid tumors, by the identification of cancer stem cells, and is termed the cancer stem cell model. At least, two genomic insults are needed for cancer, as seen from studies of human childhood acute lymphoblastic leukemia. There are signature mutations for some leukemia’s and some relate to a transcription factor that guides the cell lineage of developing hematopoietic stem/progenitor cells. Similarly, some oncogenes restrict the fate of leukemia stem cells and their offspring to a single maturation pathway. In this case, a loss of intrinsic stem cell versatility seems to be a property of leukemia stem cells. To provide more effective cures for leukemia, there is the need to find ways to eliminate leukemia stem cells.

Nanotechnology-integrated ferroptosis inducers: a sharp sword against tumor drug resistance

Presently, the biggest hurdle to cancer therapy is the inevitable emergence of drug resistance. Since conventional therapeutic schedules fall short of the expectations in curbing drug resistance, the development of novel drug resistance management strategies is critical. Extensive research over the last decade has revealed that the process of ferroptosis is correlated with cancer resistance; moreover, it has been demonstrated that ferroptosis inducers reverse drug resistance. To elucidate the development and promote the clinical transformation of ferroptosis strategies in cancer therapy, we first analyzed the roles of key ferroptosis-regulating molecules in the progression of drug resistance in-depth and then reviewed the design of ferroptosis-inducing strategies based on nanotechnology for overcoming drug resistance, including glutathione depletion, reactive oxygen species generation, iron donation, lipid peroxidation aggregation, and multiple-drug resistance-associated tumor cell destruction. Finally, the prospects and challenges of regulating ferroptosis as a therapeutic strategy for reversing cancer therapy resistance were evaluated. This review aimed to provide a comprehensive understanding for researchers to develop ferroptosis-inducing nanoplatforms that can overcome drug resistance.

Nanomedicines for Overcoming Cancer Drug Resistance

Clinically, cancer drug resistance to chemotherapy, targeted therapy or immunotherapy remains the main impediment towards curative cancer therapy, which leads directly to treatment failure along with extended hospital stays, increased medical costs and high mortality. Therefore, increasing attention has been paid to nanotechnology-based delivery systems for overcoming drug resistance in cancer. In this respect, novel tumor-targeting nanomedicines offer fairly effective therapeutic strategies for surmounting the various limitations of chemotherapy, targeted therapy and immunotherapy, enabling more precise cancer treatment, more convenient monitoring of treatment agents, as well as surmounting cancer drug resistance, including multidrug resistance (MDR). Nanotechnology-based delivery systems, including liposomes, polymer micelles, nanoparticles (NPs), and DNA nanostructures, enable a large number of properly designed therapeutic nanomedicines. In this paper, we review the different mechanisms of cancer drug resistance to chemotherapy, targeted therapy and immunotherapy, and discuss the latest developments in nanomedicines for overcoming cancer drug resistance.

O-GlcNAcylation of ZEB1 facilitated mesenchymal pancreatic cancer cell ferroptosis

Background: Mesenchymal cancer cells, resistant to the traditional regulated cell death, are exquisitely vulnerable to ferroptosis. However, the underlying mechanism has been rarely studied. While glycolipid metabolism rewiring is a critical determination of both cancer cell mesenchymal phenotype and cell death resistance, we are interested in the underlying cross talk between glycolipid metabolism and mesenchymal cancer cell ferroptosis sensitivity. Methods: CCK-8, western blot and clone forming assay were used to access the effect of glucose on mesenchymal cancer cell ferroptosis susceptibility and O-GlcNAcylation level. GEPIA database, shRNA knockdown and various pharmacological inhibitors were used to analyze the relationship between O-GlcNAcylation and mesenchymal cancer cell ferroptosis in vitro and in vivo. A series of experiments were conducted to investigate the underlying mechanisms of glucose induced ZEB1 O-GlcNAcylation on mesenchymal cancer cell ferroptosis susceptibility. Results: Mesenchymal pancreatic cancer cells O-GlcNAcylation level and ferroptosis cell death was significantly increased under high glucose condition in vitro and in vivo. O-GlcNAcylation of ZEB1, rather than other transcription factors, was involved in this process. Mechanistically, glucose triggered ZEB1 O-GlcNAcylation at Ser555 site enhanced its stabilization and nuclear translocation, induced lipogenesis associated genes, FASN and FADS2, transcription activity, which ultimately resulted in lipid peroxidation dependent mesenchymal pancreatic cancer cell ferroptosis. Conclusions: These results identify a novel role of glycolipid metabolism and O-GlcNAcylation in mesenchymal cancer cells ferroptosis susceptibility, which broaden the molecular mechanism of ferroptosis and suggested a potential clinical therapeutic strategy for refractory tumors.

High levels of NRF2 sensitize temozolomide-resistant glioblastoma cells to ferroptosis via ABCC1/MRP1 upregulation

Glioblastoma patients have a poor prognosis mainly due to temozolomide (TMZ) resistance. NRF2 is an important transcript factor involved in chemotherapy resistance due to its protective role in the transcription of genes involved in cellular detoxification and prevention of cell death processes, such as ferroptosis. However, the relation between NRF2 and iron-dependent cell death in glioma is still poorly understood. Therefore, in this study, we analyzed the role of NRF2 in ferroptosis modulation in glioblastoma cells. Two human glioblastoma cell lines (U251MG and T98G) were examined after treatment with TMZ, ferroptosis inducers (Erastin, RSL3), and ferroptosis inhibitor (Ferrostatin-1). Our results demonstrated that T98G was more resistant to chemotherapy compared to U251MG and showed elevated levels of NRF2 expression. Interestingly, T98G revealed higher sensitivity to ferroptosis, and significant GSH depletion upon system xc^- blockage. NRF2 silencing in T98G cells (T98G-shNRF2) significantly reduced the viability upon TMZ treatment. On the other hand, T98G-shNRF2 was resistant to ferroptosis and reverted intracellular GSH levels, indicating that NRF2 plays a key role in ferroptosis induction through GSH modulation. Moreover, silencing of ABCC1, a well-known NRF2 target that diminishes GSH levels, has demonstrated a similar collateral sensitivity. T98G-siABCC1 cells were more sensitive to TMZ and resistant to Erastin. Furthermore, we found that NRF2 positively correlates with ABCC1 expression in tumor tissues of glioma patients, which can be associated with tumor aggressiveness, drug resistance, and poor overall survival. Altogether, our data indicate that high levels of NRF2 result in collateral sensitivity on glioblastoma via the expression of its pro-ferroptotic target ABCC1, which contributes to GSH depletion when the system xc^- is blocked by Erastin. Thus, ferroptosis induction could be an important therapeutic strategy to reverse drug resistance in gliomas with high NRF2 and ABCC1 expression.

Metabolic Intervention Nanoparticles for Triple-Negative Breast Cancer Therapy via Overcoming FSP1-Mediated Ferroptosis Resistance

Triple-negative breast cancer (TNBC) patients have a predisposition to poor prognosis due to the strong malignancy. Ferroptosis, a new form of cell death, is a candidate treatment for TNBC owing to its effectiveness in killing cancer cells. However, some TNBC cells exhibit an abnormal tumor metabolism, especially the ferroptosis suppressor protein 1 (FSP1)-mediated ubiquinone redox metabolism, which can promote ferroptosis resistance. Here, rosuvastatin (RSV) is encapsulated in silk fibroin (SF) nanoparticle (designated as Cu-SF(RSV) NPs) for TNBC inhibition by overcoming FSP1-mediated ferroptosis resistance. RSV intervenes in metabolic mevalonate pathway to disturb the redox homeostasis regulated by CoQ/FSP1 axis, thereby overcoming ferroptosis resistance. Besides, Cu-SF(RSV) NPs can generate reactive oxygen species and deplete glutathione to facilitate redox stress, thereby amplifying ferroptosis effect. Thus, it is anticipated that the metabolic intervention nanoparticles, Cu-SF(RSV) NPs, can be exploited as a promising therapeutic platform for clinical TNBC treatment.

Ferroptosis Modulation: Potential Therapeutic Target for Glioblastoma Treatment

Glioblastoma multiforme is a lethal disease and represents the most common and severe type of glioma. Drug resistance and the evasion of cell death are the main characteristics of its malignancy, leading to a high percentage of disease recurrence and the patients’ low survival rate. Exploiting the modulation of cell death mechanisms could be an important strategy to prevent tumor development and reverse the high mortality and morbidity rates in glioblastoma patients. Ferroptosis is a recently described type of cell death, which is characterized by iron accumulation, high levels of polyunsaturated fatty acid (PUFA)-containing phospholipids, and deficiency in lipid peroxidation repair. Several studies have demonstrated that ferroptosis has a potential role in cancer treatment and could be a promising approach for glioblastoma patients. Thus, here, we present an overview of the mechanisms of the iron-dependent cell death and summarize the current findings of ferroptosis modulation on glioblastoma including its non-canonical pathway. Moreover, we focused on new ferroptosis-inducing compounds for glioma treatment, and we highlight the key ferroptosis-related genes to glioma prognosis, which could be further explored. Thereby, understanding how to trigger ferroptosis in glioblastoma may provide promising pharmacological targets and indicate new therapeutic approaches to increase the survival of glioblastoma patients.

Co-loaded lapatinib/PAB by ferritin nanoparticles eliminated ECM-detached cluster cells via modulating EGFR in triple-negative breast cancer

Cancer stem cell (CSC) cluster of triple-negative breast cancer (TNBC) is suggested to be responsible for therapy resistance, metastatic process and cancer recurrence, yet the sensitivity of CSC clusters of TNBC to ferroptosis remains elusive in a great measure. Current research revealed that epidermal growth factor receptor (EGFR) reinforced CD44-mediated TNBC cell clustering, whether blockade of EGFR has synergistic effects on erastin-induced tumor inhibition of CSC clusters is still poorly understood. Here, we found that fraction of CD24^lowCD44^high cells and size of tumor spheres clearly decreased following EGFR inhibition in TNBC cells. Inhibition of EGFR promoted expression of LC3B-II via YAP/mTOR signaling pathway, indicating that EGFR-mediated autophagy which contributed to ferroptosis. In order to further verify the protective effects of EGFR on ferroptosis induced by small molecules in TNBC cells, pseudolaric acid B (PAB) which led to ferroptosis of malignant cells was selected. In our experiment, lapatinib and PAB cotreatment inhibited TNBC cells viability and restrained formation of tumor spheres, accompanied with a high level of intracellular ROS. To target delivery lapatinib and PAB to TNBC cells, lapatinib/PAB@Ferritin (L/P@Ferritin) nanoparticles were prepared; results of in vitro and in vivo showed a higher tumor suppression efficiency of L/P@Ferritin, highlighting that it might provide a new perspective for treatment of CSC clusters of TNBC.

Molecular mechanisms of ferroptosis and its role in prostate cancer therapy

Prostate cancer (PCa) is a highly prevalent disease that affects men's health worldwide and is the second most common malignancy in males. Ferroptosis is a novel form of programmed cell death characterized by iron overload and the accumulation of lipid peroxidation, which differs from the regulated cell death modes of necrosis, apoptosis, and autophagy. Substantial progress has been achieved in researching the occurrence and regulatory mechanisms of ferroptosis, which is closely associated with cancer initiation, progression, and suppression and is expected to become a new breakthrough point in the PCa treatment. This review will summarize the mechanisms involved in PCa, and we detail the molecular mechanisms of ferroptosis and its role in PCa treatment.

Ferroptosis-Driven Nanotherapeutics to Reverse Drug Resistance in Tumor Microenvironment

Ferroptosis, characterized by iron-dependent lipid reactive oxygen species (ROS) accumulation, is non-apoptotic programmed cell death highly relevant to tumor development. It was found to manipulate oncogenes and resistant mutations of cancer cells via lipid metabolism pathways converging on phospholipid glutathione peroxidase (GPX4) that squanders lipid peroxides (L-OOH) to block the iron-mediated reactions of peroxides, thus rendering resistant cancer cells vulnerable to ferroptotic cell death. By accumulating ROS and lipid peroxidation (LPO) products to lethal levels in tumor microenvironment (TME), ferroptosis-driven nanotherapeutics show a superior ability of eradicating aggressive malignancies than traditional therapeutic modalities, especially for the drug-resistant tumors with high metastasis tendency. Moreover, Fenton reaction, inhibition of GPX-4, and exogenous regulation of LPO are three major therapeutic strategies to induce ferroptosis in cancer cells, which were generally applied in ferroptosis-driven nanotherapeutics. In this review, we elaborate current trends of ferroptosis-driven nanotherapeutics to reverse drug resistance of tumors in anticancer fields at the intersection of cancer biology, materials science, and chemistry. Finally, their challenges and perspectives toward feasible translational studies are spotlighted, which would ignite the hope of anti-resistant cancer treatment.

Role of Intracellular Iron in Switching Apoptosis to Ferroptosis to Target Therapy-Resistant Cancer Stem Cells

Iron is a crucial element required for the proper functioning of the body. For instance, hemoglobin is the vital component in the blood that delivers oxygen to various parts of the body. The heme protein present in hemoglobin comprises iron in the form of a ferrous state which regulates oxygen delivery. Excess iron in the body is stored as ferritin and would be utilized under iron-deficient conditions. Surprisingly, cancer cells as well as cancer stem cells have elevated ferritin levels suggesting that iron plays a vital role in protecting these cells. However, apart from the cytoprotective role iron also has the potential to induce cell death via ferroptosis which is a non-apoptotic cell death dependent on iron reserves. Apoptosis a caspase-dependent cell death mechanism is effective on cancer cells however little is known about its impact on cancer stem cell death. This paper focuses on the molecular characteristics of apoptosis and ferroptosis and the importance of switching to ferroptosis to target cancer stem cells death thereby preventing cancer relapse. To the best of our knowledge, this is the first review to demonstrate the importance of intracellular iron in regulating the switching of tumor cells and therapy resistant CSCs from apoptosis to ferroptosis.

Drug resistance in cancer therapy: the Pandora's Box of cancer stem cells

Drug resistance is the main culprit of failure in cancer therapy that may lead to cancer relapse. This resistance mostly originates from rare, but impactful presence of cancer stem cells (CSCs). Ability to self-renewal and differentiation into heterogeneous cancer cells, and harboring morphologically and phenotypically distinct cells are prominent features of CSCs. Also, CSCs substantially contribute to metastatic dissemination. They possess several mechanisms that help them to survive even after exposure to chemotherapy drugs. Although chemotherapy is able to destroy the bulk of tumor cells, CSCs are left almost intact, and make tumor entity resistant to treatment. Eradication of a tumor mass needs complete removal of tumor cells as well as CSCs. Therefore, it is important to elucidate key features underlying drug resistance raised by CSCs in order to apply effective treatment strategies. However, the challenging point that threatens safety and specificity of chemotherapy is the common characteristics between CSCs and normal peers such as signaling pathways and markers. In the present study, we tried to present a comprehensive appraisal on CSCs, mechanisms of their drug resistance, and recent therapeutic methods targeting this type of noxious cells.