Role of ferroptosis in gastrointestinal tumors: From mechanisms to therapies

Red ginseng polysaccharide promotes ferroptosis in gastric cancer cells by inhibiting PI3K/Akt pathway through down-regulation of AQP3

OBJECTIVE

This study aims to investigate the effect of red ginseng polysaccharide (RGP) on gastric cancer (GC) development and explore its mechanism.

METHODS

GC cell lines AGS were treated with varying concentrations of RGP (50, 100, and 200 μg/mL). AGS cells treated with 200 μg/mL RGP were transfected with aquaporin 3 (AQP3) overexpression vector. Cell proliferation, viability, and apoptosis were evaluated by MTT, colony formation assay, and flow cytometry, respectively. Real-time quantitative reverse transcription PCR (qRT-PCR) was used to detect the expression of AQP3. The levels of Fe2+, malondialdehyde, and lactate dehydrogenase were measured using their respective detection kits, and the reactive oxygen species levels was determined by probe 2',7'-dichlorodihydrofluorescein diacetate. The expression of ferroptosis-related protein and PI3K/Akt pathway-related protein were assessed by western blot. In vivo experiments in nude mice were performed and the mice were divided into four groups (n = 5/group) which gavage administrated with 150 mg/kg normal saline, and 75, 150, 300 mg/kg RGP, respectively. Their tumor weight and volume were recorded.

RESULTS

RGP treatment effectively inhibited the proliferation and viability of AGS cells in a dosage-dependent manner and induced apoptosis. It induced ferroptosis in AGS cells, as well as inhibiting the expression of PI3K/Akt-related proteins. AQP3 overexpression could reversed the effect of RGP treatment on ferroptosis. Confirmatory in vivo experiments showed that RGP could reduce the growth of implanted tumor, with increased RGP concentration resulting in greater tumor inhibitory effects.

CONCLUSION

RGP might have therapeutic potential against GC, effectively inhibiting the proliferation and viability of AGS cells.

Baicalein, a component of banxia xiexin decoction, alleviates CPT-11-induced gastrointestinal dysfunction by inhibiting ALOX15-mediated ferroptosis

Baicalein, one of the active ingredients of banxia xiexin decoction, has good therapeutic efficacy in treating diarrhea and improving gastrointestinal dysfunction. The role and mechanism of Baicalein on irinotecan (CPT-11)-induced gastrointestinal dysfunction are the focus of this study. Concretely, CPT-11 induced delayed diarrhea rat model and intestinal epithelial cell (IEC)-6 cell injury model with Baicalein treatment as needed. Colonic pathological changes were analyzed by hematoxylin-eosin staining, and inflammatory factor expressions in serum were determined by enzyme-linked immunosorbent assay. Immunohistochemistry and western blot were performed to quantify ferroptosis-related protein expressions. Thiobarbituric acid reactive substances (TBARS) kits and colorimetric assay kit were applied to detect lipid peroxidation levels and Fe2+ content, respectively. In vitro experiments also included quantitative real-time polymerase chain reaction, cell counting kit-8, and C11 BODIPY staining. CPT-11 induced aggravation of intestinal tissue damage, inflammatory factor release, Fe2+ accumulation, upregulation of lipid peroxidation and 15-Lipoxygenase (ALOX15) expression, and downregulation of glutathione peroxidase 4 (Gpx4) and SLC7A11 in vivo in rats; however, Baicalein dose-dependently reversed the effects of CPT-11. Baicalein elevated cell viability, reduced lipid peroxidation and Fe2+ accumulation, and elevated Gpx4 and SLC7A11 levels, whereas ALOX15 overexpression reversed the effects of Baicalein on a CPT-11-induced IEC-6 cell injury model. In conclusion, Baicalein plays a mitigating role in CPT-11-induced delayed diarrhea via ALOX15-mediated ferroptosis.

A new ferroptosis-related signature model including messenger RNAs and long non-coding RNAs predicts the prognosis of gastric cancer patients

Background and Objectives

Gastric cancer (GC) is among the most malignant tumor types, which causes heavy healthy and economic burden to the people and societies all around the world. Establishment of an effective set of prognostic marker will benefit a lot to the treatment of GC patients clinically. Ferroptosis is a newly identified regulated cell death modality, with tight relevance with GC development. However, its application in the prognosis of GC has not been studied in detail. Deregulated messenger RNA (mRNA) and long non-coding RNA (lncRNA) expression profile in tumor can serve as novel prognostic marker for predicting the survival and cancer relapse in patients.

Methods

We downloaded ferroptosis-related gene expression microarray data, clinicopathologic information and a list of 259 ferroptosis-related genes from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and Ferroptosis database, respectively. Then, correlation analysis, univariate and multivariate Cox regression analysis were used to construct a novel prognostic model for GC. Then, we validated the model in the GEO datasets. Finally, we evaluated the differences in immune microenvironment between high- and low-risk groups.

Results

We utilized the ferroptosis-related mRNA and lncRNA profile to successfully construct a prognostic model (incorporating 2 mRNAs and 15 lncRNAs) in GC. Our model, integrating diverse clinical traits and critical factors of GC, showed desirable efficacy in the prognosis of GC patients. This model also manifested effectively in validation by using external patients' data.

Conclusions

Our study developed a novel ferroptosis-related signature to predict the prognosis of gastric cancer patients. The ferroptosis-related signature had a favorable predictive ability. This model may greatly boost the treatment of GC patients in clinical practice.

Role of ferroptosis and its non-coding RNA regulation in hepatocellular carcinoma

Ferroptosis is a newly discovered form of programmed cell death that involves the accumulation of iron-dependent lipid peroxides and plays a vital role in the tumorigenesis, development, and drug resistance of various tumors such as hepatocellular carcinoma (HCC). As a hotspot in molecular biology, non-coding RNAs (ncRNAs) participate in the initiation and progression of HCC, either act as oncogenes or tumor suppressors. Recent studies have shown that ncRNAs can regulate ferroptosis in HCC cells, which would affect the tumor progression and drug resistance. Therefore, clarifying the underlying role of ferroptosis and the regulatory role of ncRNA on ferroptosis in HCC could develop new treatment interventions for this disease. This review briefly summarizes the role of ferroptosis and ferroptosis-related ncRNAs in HCC tumorigenesis, progression, treatment, drug resistance and prognosis, for the development of potential therapeutic strategies and prognostic markers in HCC patients.

New Iron Metabolic Pathways and Chelation Targeting Strategies Affecting the Treatment of All Types and Stages of Cancer

There is new and increasing evidence from in vitro, in vivo and clinical studies implicating the pivotal role of iron and associated metabolic pathways in the initiation, progression and development of cancer and in cancer metastasis. New metabolic and toxicity mechanisms and pathways, as well as genomic, transcription and other factors, have been linked to cancer and many are related to iron. Accordingly, a number of new targets for iron chelators have been identified and characterized in new anticancer strategies, in addition to the classical restriction of/reduction in iron supply, the inhibition of transferrin iron delivery, the inhibition of ribonucleotide reductase in DNA synthesis and high antioxidant potential. The new targets include the removal of excess iron from iron-laden macrophages, which affects anticancer activity; the modulation of ferroptosis; ferritin iron removal and the control of hyperferritinemia; the inhibition of hypoxia related to the role of hypoxia-inducible factor (HIF); modulation of the function of new molecular species such as STEAP4 metalloreductase and the metastasis suppressor N-MYC downstream-regulated gene-1 (NDRG1); modulation of the metabolic pathways of oxidative stress damage affecting mitochondrial function, etc. Many of these new, but also previously known associated iron metabolic pathways appear to affect all stages of cancer, as well as metastasis and drug resistance. Iron-chelating drugs and especially deferiprone (L1), has been shown in many recent studies to fulfill the role of multi-target anticancer drug linked to the above and also other iron targets, and has been proposed for phase II trials in cancer patients. In contrast, lipophilic chelators and their iron complexes are proposed for the induction of ferroptosis in some refractory or recurring tumors in drug resistance and metastasis where effective treatments are absent. There is a need to readdress cancer therapy and include therapeutic strategies targeting multifactorial processes, including the application of multi-targeting drugs involving iron chelators and iron-chelator complexes. New therapeutic protocols including drug combinations with L1 and other chelating drugs could increase anticancer activity, decrease drug resistance and metastasis, improve treatments, reduce toxicity and increase overall survival in cancer patients.

Arenobufagin causes ferroptosis in human gastric cancer cells by increasing rev-erbα expression

Background and aims

Gastric cancer is the fifth most diagnosed malignant tumor worldwide with limited effective chemotherapy. Ferroptosis is a new type of programmed cell death, which is becoming as a novel therapeutic target for tumors. Arenobufagin (ArBu) is a bufadienolide isolated from toad skin and venom, which exhibits broad-spectrum anti-tumor activity. It is unclear whether ArBu causes ferroptosis, thereby exhibiting anti-tumor activity in gastric cancer. We aimed to determine whether ArBu causes ferroptosis in cultured human gastric cancer cells.

Experimental procedure

Different human gastric cancer cells were treated with ArBu (5-20 μM, 48 h). Indicators of apoptosis and ferroptosis were measured. CRISPR/Cas-9 system was employed to delete Nr1d1 gene.

Results

ArBu incubation reduced cell viability in a concentration-dependent manner. ArBu caused ferroptosis but not apoptosis at a lower concentration (10 μM), despite it caused both of them at a higher concentration (20 μM). Cotreatment with a selective ferroptosis inhibitor ferrostatin-1 protected against ArBu (10 μM)-induced reduction in cell viability. ArBu-mediated ferroptosis was associated with abnormal expression of genes involved in iron uptake, lipid peroxidation, and antioxidants. Particularly, Nr1d1 gene expression was most significantly increased after ArBu treatment. Furthermore, activating Rev-erbα encoded by Nr1d1 by a selective agonist GSK4112 (1 and 2 μM, 48 h) caused ferroptosis. In contrast, Rev-erbα knockout using the CRISPR/Cas-9 system diminished ArBu-induced ferroptosis in cultured human gastric cancer cells.

Conclusion

ArBu causes ferroptosis by increasing Rev-erbα expression in human gastric cancer cells. This has implications of ArBu as a promising therapy for gastric cancer.

Section

1. Natural Products.

Taxonomy classification by EVISE

Traditional medicine, pharmacology, gastric cancer, signal pathway.

Extracellular vesicles, a novel model linking bacteria to ferroptosis in the future?

Ferroptosis is a recently discovered modulated cell death mechanism caused by the accumulation of iron-dependent lipid peroxides to toxic levels and plays an important role in tumor immunology and neurology. Recent studies have shown that ferroptosis may play a crucial role in bacterial infection pathogenesis, which may be useful in anti-infection therapies. However, how bacteria enter cells to induce ferroptosis after invading the host immune system remains largely unknown. In addition, the current studies only focus on the relationship between a single bacterial species or genus and host cell ferroptosis, and there is no systematic summary of its regulatory mechanism. Therefore, our review firstly sums up the role of ferroptosis in bacterial infection and its regulatory mechanism, and innovatively speculates on the function and potential mechanism of extracellular vesicles (EVs) in bacterial-induced ferroptosis, in order to provide possible novel directions and ideas for future anti-infection research. KEY POINTS: • Ferroptosis presents a novel mechanism for bacterial host interaction • EVs provide the potential mechanism for bacterial-induced ferroptosis • The relationship of EVs with ferroptosis provides possible directions for future treatment of bacterial infection.