Targeting ferroptosis for cancer therapy: exploring novel strategies from its mechanisms and role in cancers

Identification and validation of an autophagy-related gene signature for predicting prognosis in patients with esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is the main subtype of esophageal cancer. Since autophagy-related genes (ARGs) play a key role in the pathogenesis of many tumors, including ESCC, the purpose of this study is to establish an autophagy-related prognostic risk signature based on ARGs expression profile, and to provide a new method for improving prediction of clinical outcomes. We obtained the expression profiles of ESCC from public data (GSE53625) and extracted the portion of ARGs. Differential expression analysis and enrichment analysis were performed to confirm abnormal autophagy-related biological functions. Univariate and multivariate Cox regression analyses were performed on RNA microarray data (GSE53625) to construct a prognostic risk signature associated with autophagy. The performance of the model was evaluated by receiver operating characteristic (ROC) analysis, survival analysis and Brier score. The model was subjected to bootstrap internal validation. The potential molecular mechanism of gene signature was explored by gene set enrichment analysis (GSEA). Spearman correlation coefficient examined the correlation between risk score and immune status and ferroptosis. The expression levels of genes and proteins were validated by qRT-PCR and immunohistochemistry in ESCC cell lines and ESCC tissues. We constructed and validated an autophagy-related prognostic risk signature in 179 patients with ESCC. The long-term survival of patients in high-risk group was lower than that in low-risk group (log-rank, P value < 0.001). ROC analysis and Brier score confirmed the reliability of the signature. GSEA results showed significant enrichment of cancer- and autophagy-related signaling pathways in the high-risk ESCC patients and immunoregulatory signaling pathways in the low-risk ESCC patients. Correlation analysis showed that the risk signature can effectively predict the effect of immunotherapy. About 33.97% (71/209) ferroptosis-related genes were significantly correlated with risk scores. Finally, the results of qRT-PCR and immunohistochemistry experiments were consistent with bioinformatics analysis. In brief, we constructed a novel autophagy-related gene signature (VIM, UFM1, TSC2, SRC, MEFV, CTTN, CFTR and CDKN1A), which could improve the prediction of clinical outcomes in patients with ESCC.

Ferroptosis triggered by dihydroartemisinin facilitates chlorin e6 induced photodynamic therapy by inhibiting GPX4 and enhancing ROS

Photodynamic therapy (PDT) is noninvasive, low toxicity, and photo-selective, but may be resisted by malignant cells. A previous study found chlorin e6 (Ce6) mediated PDT showed drug resistance in lung cancer cells (LLC), which may be associated with PDT-induced DNA damage response (DDR). DDR may up-regulate glutathione peroxidase 4 (GPX4), which in turn degrade ROS induced by PDT. However, dihydroartemisinin (DHA) was found to down-regulate GPX4. Accordingly, the DHA was hypothesized to improve the resistance to PDT. The present work explores the mechanism of Ce6 mediated drug resistance and reveals whether DHA can enhance the efficacy of PDT by suppressing GPX4. The in vitro experiments found Ce6 treatment did not inhibit the viability of LLC within 6 hr without inducing significant apoptosis, suggesting LLC were resistant to PDT. Further investigation demonstrated PDT could damage DNA and up-regulate GPX4, thus degrading the generated ROS. DHA effectively inhibited the viability of LLC and induced apoptosis. Importantly, DHA displayed a prominent inhibitory effect on the GPX4 expression and thereby triggered ferroptosis. Combining DHA with Ce6 for treatment of LLC resulted in the suppressed GPX4 and elevated ROS. Finally, the findings showed DHA combined with Ce6 exhibited superb anti-lung cancer efficacy. In summary, Ce6 PDT damages DNA, up-regulates GPX4 to degrade ROS, thereby inducing drug resistance. Down-regulation of GPX4 by DHA-triggered ferroptosis significantly enhances the efficacy of PDT. This study provides an outstanding theoretical basis for the regulation of the intratumoral redox system and improving PDT efficacy against lung cancer by herbal monomer DHA.

Induction and application of ferroptosis in cancer therapy

At present, more than one cell death pathways have been found, one of which is ferroptosis. Ferroptosis was discovered in 2012 and described as an iron-dependent and lipid peroxidation-driven regulated cell death pathway. In the past few years, ferroptosis has been shown to induce tumor cell death, providing new ideas for tumor treatment. In this article, we summarize the latest advances in ferroptosis-induced tumor therapy at the intersection of tumor biology, molecular biology, redox biology, and materials chemistry. First, we state the characteristics of ferroptosis in cells, then introduce the key molecular mechanism of ferroptosis, and describes the relationship between ferroptosis and oxidative stress signaling pathways. Finally, we focused on several types of ferroptosis inducers discovered by scholars, and the application of ferroptosis in systemic chemotherapy, radiotherapy, immunotherapy and nanomedicine, in the hope that ferroptosis can exert its potential in the treatment of tumors.

Ferroptosis in Intracerebral Hemorrhage: A Panoramic Perspective of the Metabolism, Mechanism and Theranostics

Iron is one of the most crucial elements in the human body. In recent years, a kind of programmed, non-apoptotic cell death closely related to iron metabolism-called ferroptosis- has aroused much interest among many scientists. Ferroptosis also interacts with other pathways involved in cell death including iron abnormality, the cystine/glutamate antiporter and lipid peroxidation. Together these pathological pathways exert great impacts on intracerebral hemorrhage (ICH), a lethal cerebrovascular disease with a high incidence rate and mortality rate. Furthermore, the ferroptosis also affects different brain cells (neurons and neuroglial cells) and different organelles (mitochondria and endoplasmic reticulum). Clinical treatments for ferroptosis in ICH have been closely investigated recently. This perspective provides a comprehensive summary of ferroptosis mechanisms after ICH and its interaction with other cell death patterns. Understanding the role of ferroptosis in ICH will open new windows for the future treatments and preventions for ICH and other intracerebral diseases.

Drug Repositioning and Subgroup Discovery for Precision Medicine Implementation in Triple Negative Breast Cancer

Simple Summary

The heterogeneity of complicated diseases like cancer negatively affects patients’ responses to treatment. Finding homogeneous subgroups of patients within the cancer population and finding the appropriate treatment for each subgroup will improve patients’ survival. In this study, we focus on triple-negative breast cancer (TNBC), where approximately 80% of patients do not entirely respond to chemotherapy. Our aim is to find subgroups of TNBC patients and identify drugs that have the potential to tailor treatments for each group through drug repositioning. After applying our method to TNBC, we found that different targeted mechanisms were suggested for different groups of patients. Our findings could help the research community to gain a better understanding of different subgroups within the TNBC population and can help the drugs to be repurposed with explainable results regarding the targeted mechanism.

Abstract

Breast cancer (BC) is the leading cause of death among female patients with cancer. Patients with triple-negative breast cancer (TNBC) have the lowest survival rate. TNBC has substantial heterogeneity within the BC population. This study utilized our novel patient stratification and drug repositioning method to find subgroups of BC patients that share common genetic profiles and that may respond similarly to the recommended drugs. After further examination of the discovered patient subgroups, we identified five homogeneous druggable TNBC subgroups. A drug repositioning algorithm was then applied to find the drugs with a high potential for each subgroup. Most of the top drugs for these subgroups were chemotherapy used for various types of cancer, including BC. After analyzing the biological mechanisms targeted by these drugs, ferroptosis was the common cell death mechanism induced by the top drugs in the subgroups with neoplasm subdivision and race as clinical variables. In contrast, the antioxidative effect on cancer cells was the common targeted mechanism in the subgroup of patients with an age less than 50. Literature reviews were used to validate our findings, which could provide invaluable insights to streamline the drug repositioning process and could be further studied in a wet lab setting and in clinical trials.

Ferroptosis-associated gene SLC7A11 is upregulated in NSCLC and correlated with patient’s poor prognosis: An integrated bioinformatics analysis

Objective

Ferroptosis is a type of programmed cell death dependent on iron and characterized by the accumulation of lipid peroxides, which was involved in the progression of malignant tumors including non-small cell lung cancer (NSCLC).

Material/methods

Ferroptosis inhibiting gene solute carrier family 7 member 11 (SLC7A11) mRNA expression was investigated in the database of TCGA and Oncomine and compared between the cancer tissue and the normal corresponding tissue of NSCLC patients. SLC7A11 gene mutation of NSCLC was investigated in the TCGA database by the online data analysis tool of Catalog of Somatic Mutations in Cancer (COSMIC) and cBioPortal. The protein–protein interaction (PPI) network of SLC7A11 and associated genes were constructed with the STRING database. Gene ontology (GO) and the KEGG pathway of genes involved in the PPI network were explored and demonstrated by a bubble plot. Progression-free survival (PFS), overall survival (OS) and postprogression survival (PPS) between SLC7A11high and SLC7A11low expression groups were compared and demonstrated by the survival curve.

Results

SLC7A11 mRNA was upregulated in cancer tissues compared to paired normal tissues in colorectal adenocarcinoma, esophageal squamous cell carcinoma, lung squamous cell carcinoma rectum adenocarcinoma and uterine corpus endometrial carcinoma. Missense and synonymous substitutions were 66.67% and 16.67% for lung squamous cell carcinoma. For lung adenocarcinoma, the missense and synonymous substitutions were 66.67% and 33.33% respectively. In the case of single nucleotide mutation, A>T, C>G, G>A, G>T for lung squamous cell carcinoma and G>T, C>A, G>A, T> for lung adenocarcinoma were the most common mutations in the SLC7A11 coding strand. Fifty-one genes were included in the PPI network with an edge number of 287, average node degree of 11.3 and local clustering coefficient of 0.694, which demonstrated that the PPI network was enriched significantly (p = 1.0 × 10−16). In terms of the KEGG pathway, the SLC7A11 and PPI-involved genes were mainly enriched in ferroptosis, NSCLC, pathways in cancer, tp53 signaling pathway, etc. The overall survival (OS) in the SLC7A11high group was significantly lower than those of SLC7A11low groups in NSCLC (HR = 1.15, 95% CI: 1.02–1.31, p = 0.027). However, the progression-free survival (PFS) (HR = 1.17, 95% CI: 0.97–1.42, p = 0.098) and postprogression survival (PPS) (HR = 1.00, 95% CI: 0.78–1.29, p = 0.97) between SLC7A11high and SLC7A11low expression groups were not statistically different.

Conclusion

SLC7A11 was upregulated in NSCLC and correlated with the patient’s poor overall survival. SLC7A11 may be a potential target for NSCLC treatment through the ferroptosis pathway.

Targeting the Tumor Microenvironment: A Literature Review of the Novel Anti-Tumor Mechanism of Statins

Statins is widely used in clinical practice as lipid-lowering drugs and has been proven to be effective in the treatment of cardiovascular, endocrine, metabolic syndrome and other diseases. The latest preclinical evidence shows that statins have anti-proliferation, pro-apoptotic, anti-invasion and radiotherapy sensitization effects on tumor cells, suggesting that statins may become a new type of anti-tumor drugs. For a long time, mevalonate pathway has been proved to play a supporting role in the development of tumor cells. As an effective inhibitor of mevalonate pathway, statins have been proved to have a direct auxiliary anti-tumor effect in a large number of studies. In addition, anti-tumor effects of statins through ferroptosis, pyroptosis, autophagy and tumor microenvironment (TME) have also been gradually discovered. However, the specific mechanism of the antitumor effect of statins in the tumor microenvironment has not been clearly elucidated. Herein, we reviewed the antitumor effects of statins in tumor microenvironment, focusing on hypoxia microenvironment, immune microenvironment, metabolic microenvironment, acid microenvironment and mechanical microenvironment.

A Novel Ferroptosis-Related Gene Signature to Predict Prognosis in Patients with Head and Neck Squamous Cell Carcinoma

The clinical TNM staging system is currently used to evaluate the prognosis of head and neck squamous cell carcinoma (HNSCC). The 5-year survival rate for patients with HNSCC is less than 50%, which is attributed to the lack of reliable prognostic biomarkers. Ferroptosis-related genes (FRGs) regulate cancer initiation and progression. Therefore, we analyzed the correlation between FRGs and the clinical outcomes of patients with HNSCC. A typical prognostic model of FRGs for HNSCC was constructed using bioinformatics tools and data from public databases, including The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and GeneCards. The model was generated based on the following six FRGs: ATG5, PRDX6, OTUB1, FTH1, SOCS1, and MAP3K5. The accuracy of model prediction was analyzed systematically. The overall survival (OS) of the high-risk group was significantly lower than that of the low-risk group. The AUC for 1-year, 3-year, and 5-year survival were 0.645, 0.721, and 0.737, respectively, in the training set (TCGA cohort) and 0.726, 0.620, and 0.584, respectively, in the validation set (GSE65858). The multivariate Cox regression analysis revealed that the risk score was an independent prognostic factor for HNSCC. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that six FRGs were enriched in the ferroptosis pathway. A novel FRG prognostic signature model was established for HNSCC. The findings of this study reveal that FRGs are potential biomarkers for HNSCC.

SLC7A11/ xCT is a target of miR-5096 and its restoration partially rescues miR-5096-mediated ferroptosis and anti-tumor effects in human breast cancer cells

Breast cancer cells evade cell death by overexpressing SLC7A11, which functions by transporting cystine into cells in exchange for intracellular glutamate facilitating glutathione synthesis and reducing reactive oxygen species (ROS)-mediated stress. Using an in silico approach, we predicted an miRNA (miR-5096) that can target and downregulate SLC7A11. We demonstrated SLC7A11 as a target of miR-5096 by 3'UTR luciferase assay and further validated it by identifying reduced mRNA and protein levels of SLC7A11 upon miR-5096 overexpression. miR-5096-induced ferroptotic cell death in human breast cancer cells was confirmed by concurrently increased ROS, OH^-, lipid ROS, and iron accumulation levels and decreased GSH and mitochondrial membrane potential (MitoTracker™ Orange) with mitochondrial shrinkage and partial cristae loss (observed by TEM). miR-5096 inhibited colony formation, transwell migration, and breast cancer cell invasion, whereas antimiR-5096 promoted these tumorigenic properties. Ectopic expression of SLC7A11 partly reversed miR-5096-mediated effects on cell survival, ROS, lipid peroxides, iron accumulation, GSH, hydroxyl radicals, mitochondrial membrane potential, and colony formation. miR-5096 modulated the expression of epithelial-mesenchymal transition markers in vitro and inhibited the metastatic potential of MDA-MB-231 cells in a tumor xenograft model of zebrafish larvae. Our results demonstrate that miR-5096 is a tumor-suppressive miRNA in breast cancer cells, and this paper discusses its therapeutic implications.

A Novel Autophagy-Related Long Non-Coding RNA Signature to Predict Prognosis and Therapeutic Response in Esophageal Squamous Cell Carcinoma

Background

Considering the significance of autophagy and long non-coding RNAs (lncRNAs) in the biology of esophageal squamous cell carcinoma (ESCC), the present study aimed to identify a new autophagy-related lncRNA signature to forecast the clinical outcomes of ESCC patients and to guide individualized treatment.

Methods

The expression profiles were obtained from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) database. We extracted autophagy-related genes from the Human Autophagy Database and identified autophagy-related lncRNAs through Spearman correlation analysis. Univariate, least absolute shrinkage and selection operator and multivariate Cox regression analyses were performed on GSE53625 to construct an autophagy-related lncRNAs prognostic signature. The model was subjected to bootstrap internal validation, and the expression levels of lncRNAs were verified by TCGA database. The potential molecular mechanism of the model was explored by gene set enrichment analysis (GSEA). Spearman correlation coefficient examined the correlation between risk score and ferroptosis-associated genes as well as the response to immunotherapy and chemotherapy.

Results

We identified and validated an autophagy-related lncRNAs prognostic signature in 179 patients with ESCC. The prognosis of patients in the low-risk group was significantly better than that in the high-risk group (p-value <0.001). The reliability of the model was verified by Brier score and ROC. GSEA results showed significant enrichment of cancer- and autophagy-related signaling pathways in the high-risk group and metabolism-related pathways in the low-risk group. Correlation analysis indicated that the model can effectively forecast the effect of immunotherapy and chemotherapy. About 35.41% (74/209) ferroptosis-related genes were significantly correlated with risk scores.

Conclusion

In brief, we constructed a novel autophagy-related lncRNAs signature (LINC02024, LINC01711, LINC01419, LCAL1, FENDRR, ADAMTS9-AS1, AC025244.1, AC015908.6 and AC011997.1), which could improve the prediction of clinical outcomes and guide individualized treatment of ESCC patients.

Biological protein mediated ferroptotic tumor nanotherapeutics

Ferroptosis, a cell death pathway involving iron-related generation of lipid hydroperoxides for achieving incredible tumor suppression, has reignited the hope of chemotherapy in tumor treatment in the past decade. With extensive research studies, various bioactive proteins and cellular pathways have been demonstrated to regulate the occurrence and development of ferroptosis. The gradually established ferroptotic regulatory network is conducive to find effective proteins from a holistic perspective and guides better designs for future ferroptotic tumor therapies. The first section of this review summarizes the recent advances in ferroptotic regulatory mechanisms of proteins and attempts to clarify their latent function in the ferroptotic regulatory network. Second, the existing protein-mediated ferroptotic tumor nanotherapeutic strategies were reviewed, including the protein-mediated iron supplement, cell membrane transporter inhibition, glutathione peroxidase 4 interference, glutathione depletion, bioenzyme-mediated reactive oxygen species generation, heat shock protein inhibition, and tumor-overexpressed protein-triggered drug release for ferroptotic therapy. Finally, the future expectations and challenges of ferroptotic tumor nanotherapeutics for clinical cancer therapy are highlighted.

Research progress on the occurrence and therapeutic mechanism of ferroptosis in NSCLC

Ferroptosis refers to a novel way of cell death, inconsistent with the conventional concept of apoptosis and necrosis. It shows a close association with iron metabolism and oxidative damage, as marked by the significant increase of reactive oxygen species, the decreases of mitochondrial volume, and the thickening of membrane density. Recent studies confirmed that ferroptosis is closely associated with the occurrence, development, and therapy of the tumors. As impacted by the high levels of reactive oxygen species and lipid peroxides in lung cancer tissues, it is suggested that ferroptosis is more likely to occur in lung cancer tissues, which may act as a novel approach for non-small cell lung cancer (NSCLC) therapy. In the present study, the research achievements in recent years on the regulating mechanism of ferroptosis and its effect on the occurrence and the therapy of lung cancer are reviewed.

Role of Ferroptosis-Related Genes in Stanford Type A Aortic Dissection and Identification of Key Genes: New Insights from Bioinformatic Analysis

Stanford type A aortic dissection (TAAD) is one of the most dangerous vascular diseases worldwide, and the mechanisms of its development remain unclear. Further molecular pathology studies may contribute to a comprehensive understanding of TAAD and provide new insights into diagnostic markers and potential therapeutic targets. Recent studies have identified that ferroptosis, a form of cell death, may play a previously unrecognized role in influencing the development of TAAD. In this study, we explored the pathological role of ferroptosis in TAAD by performing bioinformatics analyses. Gene set enrichment analysis (GSEA) showed that the ferroptosis-related gene (FRG) set was significantly different between normal and TAAD aortic samples at an overall level (p < 0.001). Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses explored the potential functions and pathways of FRG in TAAD. We further identified six key genes (CA9, HMOX1, IL6, CDKN1A, HIF1A, MYC) from differentially expressed FRGs in TAAD by constructing a protein–protein interaction (PPI) network, all key genes were upregulated in TAAD. Four of the key genes (CA9, IL6, CDKN1A, and HIF1A) were demonstrated to be correlated with cigarette smoke extract-induced ferroptosis in aortic vascular smooth muscle cells. These results suggest that ferroptosis is one of the essential pathological processes in the development of TAAD, and some FRGs affect TAAD development by mediating cellular ferroptosis, which provides deepening insights into the molecular mechanisms and potential therapeutic targets of TAAD.

Targeting Ferroptosis for Lung Diseases: Exploring Novel Strategies in Ferroptosis-Associated Mechanisms

Ferroptosis is an iron-dependent regulated necrosis characterized by the peroxidation damage of lipid molecular containing unsaturated fatty acid long chain on the cell membrane or organelle membrane after cellular deactivation restitution system, resulting in the cell membrane rupture. Ferroptosis is biochemically and morphologically distinct and disparate from other forms of regulated cell death. Recently, mounting studies have investigated the mechanism of ferroptosis, and numerous proteins play vital roles in regulating ferroptosis. With detailed studies, emerging evidence indicates that ferroptosis is found in multiple lung diseases, demonstrating that ferroptosis appears to be particularly important for lung diseases. The mounting interest in ferroptosis drugs specifically targeting the ferroptosis mechanism holds substantial therapeutic promise in lung diseases. The present review emphatically summarizes the functions and integrated molecular mechanisms of ferroptosis in various lung diseases, proposing that multiangle regulation of ferroptosis might be a promising strategy for the clinical treatment of lung diseases.

Molecular subtypes based on ferroptosis-related genes and tumor microenvironment infiltration characterization in lung adenocarcinoma

Recently, several molecular subtypes with different prognosis have been found in lung adenocarcinoma (LUAD). However, the characteristics of the ferroptosis molecular subtypes and the associated tumor microenvironment (TME) cell infiltration have not been fully studied in LUAD. Using 1160 lung adenocarcinoma samples, we explored the molecular subtypes mediated by ferroptosis-related genes, along with the associated TME cell infiltration. The ferroptosis score was constructed using the least absolute shrinkage and selection operator regression (LASSO) method to quantify the ferroptosis characteristics of a single tumor. Three different molecular subtypes related to ferroptosis, with different prognoses, were identified in LUAD. Analysis of TME cell infiltration revealed immune heterogeneity among the three subtypes. Cluster A was characterized by immunosuppression and was associated with stromal activation. Cluster C was characterized by a large number of immune cells infiltrating the TME, promoting tumor immune response, and it was significantly enriched in immune activation-related signaling pathways. Relatively less infiltration of immune cells was a feature of cluster B. The ferroptosis score can predict tumor subtype, immunity and prognosis. A low ferroptosis score was characterized by immune activation and good prognosis, as seen in the cluster C subtype. Relative immunosuppression and poor prognosis were the characteristics of a high ferroptosis score, as seen in cluster A and B subtypes. At the same time, the anti-PD-1/L1 immunotherapy cohort demonstrated that a low ferroptosis score was associated with higher efficacy of immunotherapy. The ferroptosis score is a promising biomarker that could be of great significance to determine the prognosis, molecular subtypes, TME cell infiltration characteristics and immunotherapy effects in patients with LUAD.

A Ferroptosis-Related Gene Model Predicts Prognosis and Immune Microenvironment for Cutaneous Melanoma

Background

Cutaneous melanoma is a common but aggressive tumor. Ferroptosis is a recently discovered cell death with important roles in tumor biology. Nevertheless, the prognostic power of ferroptosis-linked genes remained unclear in cutaneous melanoma.

Methods

Cutaneous melanoma patients of TCGA (The Cancer Genome Atlas) were taken as the training cohort while GSE65904 and GSE22153 as the validation cohorts. Multifactor Cox regression model was used to build a prognostic model, and the performance of the model was assessed. Functional enrichment and immune infiltration analysis were used to clarify the mechanisms.

Results

A five ferroptosis-linked gene predictive model was developed. ALOX5 and GCH1 were illustrated as independent predictive factors. Functional assessment showed enriched immune-linked cascades. Immune infiltrating analysis exhibited the distinct immune microenvironment.

Conclusion

Herein, a novel ferroptosis-related gene prognostic model was built in cutaneous melanoma. This model could be used for prognostic prediction, and maybe helpful for the targeted and immunotherapies.

Dual Role of Reactive Oxygen Species and their Application in Cancer Therapy

Reactive oxygen species (ROS) play a dual role in the initiation, development, suppression, and treatment of cancer. Excess ROS can induce nuclear DNA, leading to cancer initiation. Not only that, but ROS also inhibit T cells and natural killer cells and promote the recruitment and M2 polarization of macrophages; consequently, cancer cells escape immune surveillance and immune defense. Furthermore, ROS promote tumor invasion and metastasis by triggering epithelial-mesenchymal transition in tumor cells. Interestingly, massive accumulation of ROS inhibits tumor growth in two ways: (1) by blocking cancer cell proliferation by suppressing the proliferation signaling pathway, cell cycle, and the biosynthesis of nucleotides and ATP and (2) by inducing cancer cell death via activating endoplasmic reticulum stress-, mitochondrial-, and P53- apoptotic pathways and the ferroptosis pathway. Unfortunately, cancer cells can adapt to ROS via a self-adaption system. This review highlighted the bidirectional regulation of ROS in cancer. The study further discussed the application of massively accumulated ROS in cancer treatment. Of note, the dual role of ROS in cancer and the self-adaptive ability of cancer cells should be taken into consideration for cancer prevention.

Development and Validation of a Ferroptosis-Related Gene Signature for Overall Survival Prediction in Lung Adenocarcinoma

Background: Ferroptosis is an iron-dependent programmed cell death process. Recent studies have found that ferroptosis inducers hold promising potential in the treatment of lung adenocarcinoma (LUAD). However, the comprehensive analysis about the prognostic value of ferroptosis-related genes in LUAD remains to be elucidated. Methods: The RNA sequencing data and corresponding clinical information were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. A total of 259 ferroptosis-related genes were extracted from FerrDb website. The ferroptosis-related prognostic signature was developed by least absolute shrinkage and selection operator (LASSO) Cox regression analysis in TCGA LUAD cohort, and then validated by 5 independent GEO cohorts. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) were performed to identify the difference in biological processes and functions between different risk groups. The expression levels of core prognostic genes were then verified in LUAD samples by immunohistochemistry (IHC) and erastin-treated LUAD cell lines by real-time polymerase chain reaction (PCR). The potential roles of GPX2 and DDIT4 as ferroptosis drivers in LUAD cell line were further confirmed by in vitro experiments. Results: A total of 20 intersecting genes between 70 ferroptosis-related DEGs and 45 potential prognostic genes were obtained for LASSO Cox regression analysis. The ferroptosis-related prognostic signature was developed by 7 core prognostic DEGs, and stratified LUAD patients into two risk groups. Kaplan-Meier analysis showed that the overall survival (OS) of LUAD patients in the high-risk group was significantly worse than that of the low-risk group. External validation of 5 independent GEO cohorts further confirmed that the ferroptosis-related prognostic signature was an ideal biomarker for predicting the survival of LUAD patients. Significant enrichment of fatty acid metabolism and cell cycle-related pathways were found in different risk groups. The expression patterns of 7 core prognostic genes in LUAD and adjacent normal lung tissues were validated by IHC, which was almost consistent with the results from public database. Furthermore, the changes related to cell cycle and ferroptosis after erastin treatment were also validated in LUAD cell lines. In addition, silencing GPX2 or DDIT4 could partially reverse the erastin-induced ferroptosis. Conclusion: In summary, the ferroptosis-related prognostic signature based on 7 core prognostic DEGs indicated superior predictive performance of LUAD patients. Targeting ferroptosis holds potential to be a therapeutic alternative for LUAD.

Molecular Mechanisms of Antiproliferative Effects of Natural Chalcones

Simple Summary

Despite the important progress in cancer treatment in the past decades, the mortality rates in some types of cancer have not significantly decreased. Therefore, the search for novel anticancer drugs has become a topic of great interest. Chalcones, precursors of flavonoid synthesis in plants, have been documented as natural compounds with pleiotropic biological effects including antiproliferative/anticancer activity. This article focuses on the knowledge on molecular mechanisms of antiproliferative action of chalcones and draws attention to this group of natural compounds that may be of importance in the treatment of cancer disease.

Abstract

Although great progress has been made in the treatment of cancer, the search for new promising molecules with antitumor activity is still one of the greatest challenges in the fight against cancer due to the increasing number of new cases each year. Chalcones (1,3-diphenyl-2-propen-1-one), the precursors of flavonoid synthesis in higher plants, possess a wide spectrum of biological activities including antimicrobial, anti-inflammatory, antioxidant, and anticancer. A plethora of molecular mechanisms of action have been documented, including induction of apoptosis, autophagy, or other types of cell death, cell cycle changes, and modulation of several signaling pathways associated with cell survival or death. In addition, blockade of several steps of angiogenesis and proteasome inhibition has also been documented. This review summarizes the basic molecular mechanisms related to the antiproliferative effects of chalcones, focusing on research articles from the years January 2015–February 2021.

Artemisinin Derivatives Inhibit Non-small Cell Lung Cancer Cells Through Induction of ROS-dependent Apoptosis/Ferroptosis

Non-small cell lung cancer (NSCLC) is one of the major cancer-related causes of morbidity and mortality worldwide. Despite the progress in lung cancer treatment, there is still an urgent need to discover novel therapeutic agents for NSCLC. Natural products represent a rich source of bioactive compounds. Through a natural compound library screening assay, we found that a group of anti-insect drugs had significant inhibitory effect on the proliferation of NSCLC cells. Among the anti-insect drugs, two derivatives of artemisinin, i.e., artesunate (ART) and dihydroartemisinin (DHA), a group of well-known anti-malarial drugs, have been shown to possess selective anti-cancer properties. Mechanistically, we found that ART and DHA induced apoptosis of A549 cells as evidenced by decreased protein level of VDAC and increased caspase 3 cleavage. Furthermore, cystine/glutamate transporter (xCT), a core negative regulator of ferroptosis, was downregulated by ART and DHA. The mRNA level of transferrin receptor (TFRC), a positive regulator of ferroptosis, was upregulated by ART and DHA. ART/DHA-induced apoptosis and ferroptosis in NSCLC cells were partly reversed by N-Acetyl-L-cysteine (NAC), a ROS scavenger, and ferrostatin-1, a ferroptosis inhibitor, respectively. These results suggest that artemisinin derivatives have anti-NSCLC activity through induction of ROS-dependent apoptosis/ferroptosis. Our findings provide the experimental basis for the potential application of artemisinin derivatives as a class of novel therapeutic drugs for NSCLC.

A Novel Ferroptosis-Associated Gene Signature to Predict Prognosis in Patients with Uveal Melanoma

Background: Uveal melanoma (UM) is the most common intraocular tumor in adults. Ferroptosis is a newly recognized process of cell death, which is different from other forms of cell death in terms of morphology, biochemistry and genetics, and has played a vital role in cancer biology. The present research aimed to construct a gene signature from ferroptosis-related genes that have the prognostic capacity of UM. Methods: UM patients from The Cancer Genome Atlas (TCGA) were taken as the training cohort, and GSE22138 from Gene Expression Omnibus (GEO) was treated as the validation cohort. A total of 103 ferroptosis-related genes were retrieved from the GeneCards. We performed Kaplan–Meier and univariate Cox analysis for preliminary screening of ferroptosis-related genes with potential prognostic capacity in the training cohort. These genes were then applied into an overall survival-based LASSO Cox regression model, constructing a gene signature. The discovered gene signature was then evaluated via Kaplan–Meier (KM), Cox, and ROC analyses in both cohorts. The Pearson correlation coefficient examined the correlations between risk score and UM common mutations and autophagy. The analyses of GSEA and immune infiltrating were performed to better study the functional annotation of the gene signature and the character of each kind of immune cell in the tumor microenvironment. Results: A seven-gene signature was found from the training cohort and validated in all cohorts by Kaplan–Meier and Cox regression analyses, revealing its independent prognosis value in UM. Moreover, ROC analysis was conducted, confirming the strong predictive ability that this signature had for UM prognosis. A total of 52.24% (256/490) autophagy-related genes were significantly correlated with risk scores. Analyses of GSEA and immune infiltrating detailed exhibited specific pathways associated with the seven-gene signature, also confirming the crucial role that Mast cells resting played in the prognosis of the seven-gene signature. Conclusions: In this study, a novel ferroptosis-related seven-gene signature (ALOX12, CD44, MAP1LC3C, STEAP3, HMOX1, ITGA6, and AIFM2/FSP1) was built. It could accurately predict UM prognosis and was related to Mast cells resting, which provides the potential for personalized outcome prediction and the development of new therapies in the UM population.

Regulated Necrotic Cell Death in Alternative Tumor Therapeutic Strategies

The treatment of tumors requires the induction of cell death. Radiotherapy, chemotherapy, and immunotherapy are administered to kill cancer cells; however, some cancer cells are resistant to these therapies. Therefore, effective treatments require various strategies for the induction of cell death. Regulated cell death (RCD) is systematically controlled by intracellular signaling proteins. Apoptosis and autophagy are types of RCD that are morphologically different from necrosis, while necroptosis, pyroptosis, and ferroptosis are morphologically similar to necrosis. Unlike necrosis, regulated necrotic cell death (RNCD) is caused by disruption of the plasma membrane under the control of specific proteins and induces tissue inflammation. Various types of RNCD, such as necroptosis, pyroptosis, and ferroptosis, have been used as therapeutic strategies against various tumor types. In this review, the mechanisms of necroptosis, pyroptosis, and ferroptosis are described in detail, and a potential effective treatment strategy to increase the anticancer effects on apoptosis- or autophagy-resistant tumor types through the induction of RNCD is suggested.