SIRT3-mediated autophagy contributes to ferroptosis-induced anticancer by inducing the formation of BECN1-SLC7A11 complex

Artemether relieves liver fibrosis by triggering ferroptosis in hepatic stellate cells via DHHC12-mediated S-palmitoylation of the BECN1 protein

Liver fibrosis, a pivotal stage in chronic liver disease progression, is driven by hepatic stellate cell (HSC) activation. Ferroptosis is a novel form of programmed cell death, which offers therapeutic potential for liver fibrosis. Although artemether (ART) exhibits antifibrotic properties, its mechanisms in liver fibrosis remain unclear. This study aimed to determine the therapeutic effects of ART on liver fibrosis and explore the role of S-palmitoylation in HSC ferroptosis.

METHODS

A mouse model of liver fibrosis was constructed by carbon tetrachloride (CCl4) injection. Transforming growth factor-β (TGF-β) was used for stimulating HSC activation in vitro. Histopathological and serological assays were performed to analyze the therapy effects of ART. Liquid Chromatography/Mass Spectrometry (LC/MS) and acyl-biotinyl exchange (ABE) were used to determine the role of S-palmitoylation in ART-induced HSC ferroptosis. Western blot and Co-Immunoprecipitation (Co-IP) were performed to examine the effects of autophagy in ART-induced HSC ferroptosis through regulating BECN1 S-palmitoylation.

RESULTS

ART ameliorated liver fibrosis by inducing HSC ferroptosis, and the ferroptosis inhibitor ferrostatin-1 (Fer-1) impaired the inhibitory effect of ART. Interestingly, the levels of S-palmitoylation were elevated by upregulating the palmitoyltransferase DHHC12 during ART-induced HSC ferroptosis. DHHC12 knockdown reduced S-palmitoylation levels and impaired ART-mediated HSC ferroptosis. RNA-seq analysis indicated that autophagy activation was essential for ART to induce HSC ferroptosis. 3-methyladenine (3-MA) suppressed autophagy and ART-induced HSC ferroptosis. Importantly, BECN1 S-palmitoylation by DHHC12 drove ART to activate autophagy. DHHC12 bound to the cysteine 21 residue of BECN1, thereby stabilizing the BECN1 protein and facilitating autophagy activation. Mutation of the cysteine 21 residue decreased BECN1 protein stability, autophagy activation and ferroptosis in ART-treated HSCs. In a mouse model of hepatic fibrosis, HSC-specific inhibition of BECN1 S-palmitoylation reversed ART-induced HSC ferroptosis and the improvement of fibrotic liver.

CONCLUSIONS

ART alleviates liver fibrosis by inducing HSC ferroptosis via DHHC12-mediated BECN1 protein S-palmitoylation.

Puerarin triggers sensitivity to ferroptosis in glioblastoma cells by activating SIRT3/NCOA4-dependent autophagy

SIRT3 has been found to involve in the tumorigenesis and progression of glioblastoma, and it is reported that puerarin can inhibit the growth of glioblastoma cells. Therefore, we aimed to investigate the biological function of SIRT3 in autophagy and ferroptosis in glioblastoma cells and study the effects of puerarin on ferroptosis and SIRT3/NCOA4-dependent autophagy in cancer cells. The results showed that overexpression of SIRT3 significantly promoted ferroptosis sensitization by reducing cell viability and GSH/GSSH ratio and increasing ROS levels, whereas knockout of SIRT3 significantly triggered cell viability and GSH/GSSH ratio and decreasing ROS levels in U87MG cells (P < 0.05). Moreover, overexpression of SIRT3 significantly also promoted the ratio of LC3-Ⅱ/Ⅰ and upregulated NCOA4 and Fe2+ levels, but downregulated the expression of p62 and FTH (P < 0.05); while knockout of SIRT3 has the opposite effects. Besides, autophagy inhibitor antagonized the effects of SIRT3 overexpression on the expression of autophagy-associated proteins and Fe2+ levels. Additionally, knockout of NCOA4 significantly increased cell viability and GSH/GSSH ratio and reduced ROS levels in RSL3-treated cells overexpressing SIRT3. Puerarin treatment significantly upregulated the levels of ROS, Fe2+, SIRT3, NCOA4, and the ratio of LC3-Ⅱ/Ⅰ, but downregulated the levels of cell viability, GSH/GSSH ratio, p62, and FTH in U87MG cells (all P < 0.05). Autophagy inhibitor, SIRT3 or NCOA4 deletion significantly reduced the effects of puerarin on the autophagy-dependent ferroptosis in U87MG cells (all P < 0.05). SIRT3 drives sensitivity to ferroptosis by activating NCOA4-mediated autophagy, and we proposed puerarin, a promising therapeutic drug for glioblastoma.

The RNA Demethyltransferase FTO Regulates Ferroptosis in Major Depressive Disorder

Major depressive disorder (MDD) is a widespread and severe mental health condition characterized by persistent low mood and loss of interest. Emerging evidence suggests that ferroptosis, an iron-dependent form of cell death, and epigenetic dysregulation contribute to the pathogenesis of MDD. This study investigates the role of RNA demethylase FTO and autophagy regulator BECN1 in ferroptosis and their regulation by the active compound ginsenoside Rb1 (GRb1) as a potential antidepressant strategy. Hippocampal tissues from postmortem MDD patient brains and mice with chronic restraint stress (CRS)-induced depression were analyzed. Ferroptosis was evaluated by analyzing the levels of markers such as glutathione (GSH) and malondialdehyde (MDA). GRb1 was administered to CRS model mice by gavage to explore its effects on ferroptosis-related pathways. The results showed that FTO and BECN1 expression was reduced in the hippocampal tissues of MDD patients and CRS model mice, promoting ferroptosis via disruption of the antioxidant system. Moreover, GRb1 treatment increased FTO and BECN1 expression, modulated m6A methylation, restored the antioxidant balance, and inhibited ferroptosis in CRS model mice. These findings reveal a novel epigenetic mechanism of ferroptosis in MDD and highlight GRb1 as a promising agent for treating depression through the targeting of ferroptosis pathways.

Endoplasmic reticulum stress induced autophagy in cancer and its potential interactions with apoptosis and ferroptosis

The endoplasmic reticulum (ER) is a dynamic organelle that is a site of the synthesis of proteins and lipids, contributing to the regulation of proteostasis, lipid metabolism, redox balance, and calcium storage/-dependent signaling events. The disruption of ER homeostasis due to the accumulation of misfolded proteins in the ER causes ER stress which activates the unfolded protein response (UPR) system through the activation of IRE1, PERK, and ATF6. Activation of UPR is observed in various cancers and therefore, its association with process of carcinogenesis has been of importance. Tumor cells effectively utilize the UPR system to overcome ER stress. Moreover, ER stress and autophagy are the stress response mechanisms operating together to maintain cellular homeostasis. In human cancers, ER stress-driven autophagy can function as either pro-survival or pro-death in a context-dependent manner. ER stress-mediated autophagy can have crosstalk with other types of cell death pathways including apoptosis and ferroptosis. In this connection, the present review has evaluated the role of ER stress in the regulation of autophagy-mediated tumorigenesis and its interactions with other cell death mechanisms such as apoptosis and ferroptosis. We have also comprehensively discussed the effect of ER stress-mediated autophagy on cancer progression and chemotherapeutic resistance.

FXR deficiency induced ferroptosis via modulation of the CBP-dependent p53 acetylation to suppress breast cancer growth and metastasis

Farnesoid X receptor (NR1H4/FXR) functions as a scavenger of lipid peroxide products and drives the proliferation and metastasis of various cancers. However, the underlying molecular mechanisms remain poorly understood. In our study, we found that the expression levels of FXR, vimentin and SLC7A11 were significantly higher in breast cancer tissues, particularly in metastatic cancer tissues compared to non-metastatic ones. Furthermore, the increased FXR expression was positively correlated with vimentin and SLC7A11 in clinical tumor specimens. In addition, a high level of FXR correlated with poor prognosis in patients with breast cancer. Both Z-Guggulsterone (Z-GS), as a pharmacological inhibitor of FXR, and silencing FXR curbed proliferation and migration of breast cancer cells by promoting ferroptosis. Notably, our results showed that FXR competitively bound to CREB-binding protein (CBP) to suppress the interaction between p53 and CBP in the nucleus, and thus prevented p53 acetylation at lys382, which was essential for upregulating the expression of SLC7A11. Conversely, FXR knockdown increased the interaction between p53 and CBP and promoted p53 acetylation, which ultimately led to facilitating ferroptosis in breast cancer cells. More importantly, we also found that Z-GS inhibited TGF-β1-induced tumor growth and metastasis of breast cancer primarily through ferroptosis via regulating CBP-dependent p53 acetylation in nude mice. In conclusion, the FXR was first reported as a tumor promoter that enhanced the proliferation and metastasis of breast cancer cells through regulating CBP-dependent p53 K382 acetylation. It proposes that FXR may serve as a potential therapeutic target for the treatment of breast cancer.

The disruption of NEAT1-miR-125b-5p-SLC1A5 cascade defines the oncogenicity and differential immune profile in head and neck squamous cell carcinoma

Metabolic reprogramming sustains malignant head and neck squamous cell carcinoma (HNSCC) to overcome stressful microenvironments, and increased glutamine uptake is a common metabolic hallmark in cancers. Since metabolic reprogramming has been recognized as a new therapeutic target for tumor cells, understanding the regulatory axis of glutamine uptake in HNSCC and its potential downstream effects in its pathogenesis of HNSCC would be incredibly beneficial. Bioinformatic analysis of the Cancer Genome Atlas (TCGA)-HNSCC dataset and RNAseq analysis performed on HNSCC indicated that SLC1A5 was the most dysregulated transporter among the seven homologous glutamate or neutral amino acid transporters in the SLC1A family. To further clarify the role of SLC1A5 in HNSCC, we knocked down SLC1A5 expression. This knockdown decelerated cell growth, induced G0/G1 arrest, diminished tumorigenicity, and increased cleavage caspase3, LC3B, and intracellular Fe2+. Inhibitors against apoptosis, autophagy, or ferroptosis rescued the cell viability repressed by SLC1A5 knockdown. SLC1A5 knockdown also suppressed glutamine uptake, enhanced oxidative stress, and increased sensitivity to cisplatin. CRISPR/dCas9-mediated SLC1A5 induction conferred cisplatin resistance and reduced apoptosis, autophagy, and ferroptosis. Reporter assays and western blot data demonstrated that miR-125b-5p targets and attenuates SLC1A5, while the si-NEAT1 increases miR-125b-5p expression. Analysis of the TCGA-HNSCC databases showed concordant upregulation of NEAT1 and downregulation of miR-125b-5p, along with SLC1A5 upregulation in tumors. Analysis of transcriptomic data revealed that tumors harboring higher SLC1A5 expression had significantly lower immune scores in CD8+, monocytes, and dendritic cells, and higher scores in M0 and M1 macrophages. Disruptions in immune modulation, metabolism, and oxidative stress components were associated with SLC1A5 aberrations in HNSCC. This study concludes that the NEAT1/miR-125b-5p/SLC1A5 cascade modulates diverse activities in oncogenicity, treatment efficacy, and immune cell profiles in head and neck/oral carcinoma.

International consensus guidelines for the definition, detection, and interpretation of autophagy-dependent ferroptosis

Macroautophagy/autophagy is a complex degradation process with a dual role in cell death that is influenced by the cell types that are involved and the stressors they are exposed to. Ferroptosis is an iron-dependent oxidative form of cell death characterized by unrestricted lipid peroxidation in the context of heterogeneous and plastic mechanisms. Recent studies have shed light on the involvement of specific types of autophagy (e.g. ferritinophagy, lipophagy, and clockophagy) in initiating or executing ferroptotic cell death through the selective degradation of anti-injury proteins or organelles. Conversely, other forms of selective autophagy (e.g. reticulophagy and lysophagy) enhance the cellular defense against ferroptotic damage. Dysregulated autophagy-dependent ferroptosis has implications for a diverse range of pathological conditions. This review aims to present an updated definition of autophagy-dependent ferroptosis, discuss influential substrates and receptors, outline experimental methods, and propose guidelines for interpreting the results.Abbreviation: 3-MA:3-methyladenine; 4HNE: 4-hydroxynonenal; ACD: accidentalcell death; ADF: autophagy-dependentferroptosis; ARE: antioxidant response element; BH2:dihydrobiopterin; BH4: tetrahydrobiopterin; BMDMs: bonemarrow-derived macrophages; CMA: chaperone-mediated autophagy; CQ:chloroquine; DAMPs: danger/damage-associated molecular patterns; EMT,epithelial-mesenchymal transition; EPR: electronparamagnetic resonance; ER, endoplasmic reticulum; FRET: Försterresonance energy transfer; GFP: green fluorescent protein;GSH: glutathione;IF: immunofluorescence; IHC: immunohistochemistry; IOP, intraocularpressure; IRI: ischemia-reperfusion injury; LAA: linoleamide alkyne;MDA: malondialdehyde; PGSK: Phen Green™ SK;RCD: regulatedcell death; PUFAs: polyunsaturated fatty acids; RFP: red fluorescentprotein;ROS: reactive oxygen species; TBA: thiobarbituricacid; TBARS: thiobarbituric acid reactive substances; TEM:transmission electron microscopy.

Context-dependent role of SIRT3 in cancer

Sirtuin 3 (SIRT3), an NAD+-dependent deacetylase, plays a key role in the modulation of metabolic reprogramming and regulation of cell death, as well as in shaping tumor phenotypes. Owing to its critical role in determining tumor-type specificity or the direction of tumor evolution, the development of small-molecule modulators of SIRT3, including inhibitors and activators, is of significant interest. In this review, we discuss recent studies on the oncogenic or tumor-suppressive functions of SIRT3, evaluate advances in SIRT3-targeted drug discovery, and present potential avenues for the design of small-molecule modulators of SIRT3 for cancer therapy.

Sulforaphane triggers Sirtuin 3-mediated ferroptosis in colorectal cancer cells via activating the adenosine 5'-monophosphate (AMP)-activated protein kinase/ mechanistic target of rapamycin signaling pathway

OBJECTIVE

This study aimed to explore the expression and biological functions of SIRT3 in colorectal cancer cells (HCT-116), the impacts of sulforaphane on the ferroptosis of HCT-116 cells and the involvement of the SIRT3/AMPK/mTOR axis in those effects.

METHODS

SIRT3-overexpressing (OE) and SIRT3-knockout (KO) cell lines were treated with different concentrations of sulforaphane, RSL-3, and IKE. Cell viability, intracellular ROS, MDA, iron levels, as well as mRNA and protein expressions of target genes were measured.

RESULTS

SIRT3 expression in HCT-116 cells was increased by ferroptosis inducers and decreased by ferroptosis inhibitors. SIRT3 overexpression reduced cell viability and increased intracellular levels of ROS, MDA, and iron, whereas SIRT3 knockdown achieved the opposite effects. SIRT3 overexpression suppressed SLC7A11 expression and promoted the activation of AMPK/mTOR pathway. Restoration of SLC7A11 expression blocked the effects of SIRT3 on ferroptosis induction and cell viability inhibition. SIRT3 effects on cell viability and ferroptosis were antagonized by inhibitors of AMPK or mTOR. Moreover, sulforaphane triggered the ferroptosis of HCT-116 cells by activating the SIRT3/AMPK/mTOR axis.

CONCLUSIONS

SIRT3 triggered SLC7A11-mediated ferroptosis in HCT-116 cells, reducing cell viability by activating the AMPK/mTOR pathway, and sulforaphane targets it to inhibit colorectal cancer.

Compounds targeting ferroptosis in breast cancer: progress and their therapeutic potential

In recent years, there has been a significant increase in the incidence of Breast cancer (BC), making it the most common cancer among women and a major threat to women's health. Consequently, there is an urgent need to discover new and effective strategies for treating BC. Ferroptosis, a novel form of cell death characterized by the accumulation of iron-dependent lipid reactive oxygen species, has emerged as a distinct regulatory pathway separate from necrosis, apoptosis, and autophagy. It is widely recognized as a crucial factor in the development and progression of cancer, offering a promising avenue for BC treatment. While significant progress has been made in understanding the mechanisms of ferroptosis in BC, drug development is still in its early stages. Numerous compounds, including phytochemicals derived from dietary sources and medicinal plants, as well as synthetic drugs (both clinically approved medications and laboratory reagents), have shown the ability to induce ferroptosis in BC cells, effectively inhibiting tumor growth. This comprehensive review aims to examine in detail the compounds that target ferroptosis in BC and elucidate their potential mechanisms of action. Additionally, the challenges associated with the clinical application of ferroptosis-inducing drugs are discussed, offering valuable insights for the development of novel treatment strategies for BC.

Autophagy and cancer drug resistance in dialogue: Pre-clinical and clinical evidence

The emergence of drug resistance is a major challenge for oncologists. Resistance can be categorized as acquired or intrinsic; the alteration of several biological mechanisms contributes to both intrinsic and acquired resistance. Macroautophagy/autophagy is the primary process in eukaryotes for the degradation of macromolecules and organelles. This process is critical in maintaining cellular homeostasis. Given its function as either a pro-survival or a pro-death phenomenon, autophagy has a complex physio-pathological role. In some circumstances, autophagy can confer chemoresistance and promote cell survival, whereas in others it can promote chemosensitivity and contribute to cell death. The role of autophagy in the modulation of cancer drug resistance reflects its impact on apoptosis and metastasis. The regulation of autophagy in cancer is mediated by various factors including AMP-activated protein kinase (AMPK), MAPK, phosphoinositide 3-kinase (PI3K)-AKT, BECN1 and ATG proteins. Non-coding RNAs are among the main regulators of autophagy, e.g., via the modulation of chemoresistance pathways. Due to the significant contribution of autophagy in cancer drug resistance, small molecule modulators and natural compounds targeting autophagy have been introduced to alter the response of cancer cells to chemotherapy. Furthermore, nanotherapeutic approaches based on autophagy regulation have been introduced in pre-clinical cancer therapy. In this review we consider the potential for using autophagy regulators for the clinical treatment of malignancies.