All-trans retinoic acid inhibits the malignant behaviors of hepatocarcinoma cells by regulating ferroptosis

Silica nanoparticles triggered epithelial ferroptosis via miR-21-5p/GCLM signaling to contribute to fibrogenesis in the lungs

The toxicity of silica nanoparticles (SiNPs) to lung is known. We previously demonstrated that exposure to SiNPs promoted pulmonary impairments, but the precise pathogenesis remains elucidated. Ferroptosis has now been identified as a unique form of oxidative cell death, but whether it participated in SiNPs-induced lung injury remains unclear. In this work, we established a rat model with sub-chronic inhalation exposure of SiNPs via intratracheal instillation, and conducted histopathological examination, iron detection, and ferroptosis-related lipid peroxidation and protein assays. Moreover, we evaluated the effect of SiNPs on epithelial ferroptosis, possible mechanisms using in vitro-cultured human bronchial epithelial cells (16HBE), and also assessed the ensuing impact on fibroblast activation for fibrogenesis. Consequently, fibrotic lesions occurred in the rat lungs, concomitantly by enhanced lipid peroxidation, iron overload, and ferroptosis. Consistently, the in vitro data showed SiNPs triggered oxidative stress and caused the accumulation of lipid peroxides, resulting in ferroptosis. Importantly, the mechanistic investigation revealed miR-21-5p as a key player in the epithelial ferroptotic process induced by SiNPs via targeting GCLM for GSH depletion. Of note, ferrostatin-1 could greatly suppress ferroptosis and alleviate epithelial injury and ensuing fibroblast activation by SiNPs. In conclusion, our findings first revealed SiNPs triggered epithelial ferroptosis through miR-21-5p/GCLM signaling and thereby promoted fibroblast activation for fibrotic lesions, and highlighted the therapeutic potential of inhibiting ferroptosis against lung impairments upon SiNPs exposure.

Targeting the regulation of iron homeostasis as a potential therapeutic strategy for nonalcoholic fatty liver disease

With aging and the increasing incidence of obesity, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. NAFLD mainly includes simple hepatic steatosis, nonalcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma (HCC). An imbalance in hepatic iron homeostasis is usually associated with the progression of NAFLD and induces iron overload, reactive oxygen species (ROS) production, and lipid peroxide accumulation, which leads to ferroptosis. Ferroptosis is a unique type of programmed cell death (PCD) that is characterized by iron dependence, ROS production and lipid peroxidation. The ferroptosis inhibition systems involved in NAFLD include the solute carrier family 7 member 11 (SLC7A11)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1)/coenzyme Q10 (CoQ10)/nicotinamide adenine dinucleotide phosphate (NADPH) regulatory axes. The main promotion system involved is the acyl-CoA synthetase long-chain family (ACSL4)/arachidonic lipoxygenase 15 (ALOX15) axis. In recent years, an increasing number of studies have focused on the multiple roles of iron homeostasis imbalance and ferroptosis in the progression of NAFLD. This review highlights the latest studies about iron homeostasis imbalance- and ferroptosis-associated NAFLD, mainly including the physiology and pathophysiology of hepatic iron metabolism, hepatic iron homeostasis imbalance during the development of NAFLD, and key regulatory molecules and roles of hepatic ferroptosis in NAFLD. This review aims to provide innovative therapeutic strategies for NAFLD.

Targeting AFP-RARβ complex formation: a potential strategy for treating AFP-positive hepatocellular carcinoma

Alpha-fetoprotein (AFP) is a glycoprotein primarily expressed during embryogenesis, with declining levels postnatally. Elevated AFP levels correlate with pathological conditions such as liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Recent investigations underscore AFP's intracellular role in HCC progression, wherein it forms complexes with proteins like Phosphatase and tensin homolog (PTEN), Caspase 3 (CASP3), and Retinoic acid receptors and Retinoid X receptors (RAR/RXR). RAR and RXR regulate gene expression linked to cell death and tumorigenesis in normal physiology. AFP impedes RAR/RXR dimerization, nuclear translocation, and function, promoting gene expression favoring cancer progression in HCC that provoked us to target AFP as a drug candidate. Despite extensive studies, inhibitors targeting AFP to disrupt complex formation and activities remain scarce. In this study, employing protein-protein docking, amino acid residues involved in AFP-RARβ interaction were identified, guiding the definition of AFP's active site for potential inhibitor screening. Currently, kinase inhibitors play a significant role in cancer treatment and, the present study explores the potential of repurposing FDA-approved protein kinase inhibitors to target AFP. Molecular docking with kinase inhibitors revealed Lapatinib as a candidate drug of the AFP-RARβ complex. Molecular dynamics simulations and binding energy calculations, employing Mechanic/Poisson-Boltzmann Surface Area (MM-PBSA), confirmed Lapatinib's stability with AFP. The study suggests Lapatinib's potential in disrupting the AFP-RARβ complex, providing a promising avenue for treating molecularly stratified AFP-positive HCC or its early stages.

Current Progress of Ferroptosis Study in Hepatocellular Carcinoma

Ferroptosis, an emerging type of programmed cell death, is initiated by iron-dependent and excessive ROS-mediated lipid peroxidation, which eventually leads to plasma membrane rupture and cell death. Many canonical signalling pathways and biological processes are involved in ferroptosis. Furthermore, cancer cells are more susceptible to ferroptosis due to the high load of ROS and unique metabolic characteristics, including iron requirements. Recent investigations have revealed that ferroptosis plays a crucial role in the progression of tumours, especially HCC. Specifically, the induction of ferroptosis can not only inhibit the growth of hepatoma cells, thereby reversing tumorigenesis, but also improves the efficacy of immunotherapy and enhances the antitumour immune response. Therefore, triggering ferroptosis has become a new therapeutic strategy for cancer therapy. In this review, we summarize the characteristics of ferroptosis based on its underlying mechanism and role in HCC and provide possible therapeutic applications.

Inhibitory effect of all-trans retinoic acid on ferroptosis in BeWo cells mediated by the upregulation of heme Oxygenase-1

INTRODUCTION

This study aimed to explore the association between ferroptosis, a newly identified type of cell death, and the role of retinoic acid in developing pregnancy complications. Therefore, the effects of all-trans retinoic acid (ATRA) on ferroptosis susceptibility in BeWo cells were assessed to understand abnormal placental development.

METHODS

BeWo cells were used as surrogates for cytotrophoblasts. The effect of ATRA on ferroptosis sensitivity was assessed on BeWo cells pretreated with ATRA or dimethyl sulfoxide (DMSO; control), following which the LDH-releasing assay was performed. The effects of ATRA pretreatment on the antioxidant defense system (including glutathione [GSH], mitochondrial membrane potential, and heme oxygenase-1 [HMOX1]) in BeWo cells were assessed using assay kits, RT-qPCR, and HMOX1 immunostaining. To evaluate the effect of ATRA on BeWo cells, HMOX1 was silenced in BeWo cells using shRNA.

RESULTS

ATRA pretreatment increased ferroptosis resistance in BeWo cells. Although with pretreatment, qPCR indicated upregulation of HMOX1, no significant change was observed in the GSH levels or mitochondrial membrane potential. This was corroborated by intensified immunostaining for heme oxygenase-1 protein (HO-1). Notably, the protective effect of ATRA against ferroptosis was negated when HO-1 was inhibited. Although HMOX1-silenced BeWo cells exhibited heightened ferroptosis sensitivity compared with controls, ATRA pretreatment counteracted ferroptosis in these cells.

DISCUSSION

ATRA pretreatment promotes BeWo cell viability by suppressing ferroptosis and upregulating HMOX1 and this can be used as a potential therapeutic strategy for addressing placental complications associated with ferroptosis.

Induction of Hepatoma Cell Pyroptosis by Endogenous Lipid Geranylgeranoic Acid-A Comparison with Palmitic Acid and Retinoic Acid

Research on retinoid-based cancer prevention, spurred by the effects of vitamin A deficiency on gastric cancer and subsequent clinical studies on digestive tract cancer, unveils novel avenues for chemoprevention. Acyclic retinoids like 4,5-didehydrogeranylgeranoic acid (4,5-didehydroGGA) have emerged as potent agents against hepatocellular carcinoma (HCC), distinct from natural retinoids such as all-trans retinoic acid (ATRA). Mechanistic studies reveal GGA's unique induction of pyroptosis, a rapid cell death pathway, in HCC cells. GGA triggers mitochondrial superoxide hyperproduction and ER stress responses through Toll-like receptor 4 (TLR4) signaling and modulates autophagy, ultimately activating pyroptotic cell death in HCC cells. Unlike ATRA-induced apoptosis, GGA and palmitic acid (PA) induce pyroptosis, underscoring their distinct mechanisms. While all three fatty acids evoke mitochondrial dysfunction and ER stress responses, GGA and PA inhibit autophagy, leading to incomplete autophagic responses and pyroptosis, whereas ATRA promotes autophagic flux. In vivo experiments demonstrate GGA's potential as an anti-oncometabolite, inducing cell death selectively in tumor cells and thus suppressing liver cancer development. This review provides a comprehensive overview of the molecular mechanisms underlying GGA's anti-HCC effects and underscores its promising role in cancer prevention, highlighting its importance in HCC prevention.

Understanding the Novel Approach of Nanoferroptosis for Cancer Therapy

As a new form of regulated cell death, ferroptosis has unraveled the unsolicited theory of intrinsic apoptosis resistance by cancer cells. The molecular mechanism of ferroptosis depends on the induction of oxidative stress through excessive reactive oxygen species accumulation and glutathione depletion to damage the structural integrity of cells. Due to their high loading and structural tunability, nanocarriers can escort the delivery of ferro-therapeutics to the desired site through enhanced permeation or retention effect or by active targeting. This review shed light on the necessity of iron in cancer cell growth and the fascinating features of ferroptosis in regulating the cell cycle and metastasis. Additionally, we discussed the effect of ferroptosis-mediated therapy using nanoplatforms and their chemical basis in overcoming the barriers to cancer therapy.

New molecular insights into ferroptosis in lung adenocarcinoma progression and pharmacological compounds for targeted therapy

BACKGROUND

The involvement of ferroptosis has been found in many pathological conditions of the lung. The genetic engineering of ferroptosis-related genes may provide a potential target for the treatment of lung adenocarcinoma (LUAD).

METHODS

Nine ferroptosis regulators and markers were collected from FerrDb and their somatic mutations and expressions were analyzed based on The Cancer Genome Atlas (TCGA)-LUAD cohort data. Least absolute shrinkage and selection operator (LASSO) and Cox regression analysis were performed to screen genes significantly associated with ferroptosis. The ferroptosis-related gene signature was constructed using TCGA-LUAD cohort data and was verified using the GSE cohort with pooled data for GSE30219, GSE31210, GSE37745 and GSE50081. Immune microenvironment component and mutation analysis were performed for genes in the ferroptosis-related gene signature.

RESULTS

All nine ferroptosis regulators and markers were differentially expressed between normal LUAD tumor tissues and adjacent normal tissues and were related to copy number variation. The expression of 1329 genes were significantly associated with nine ferroptosis regulators and markers in the TCGA-LUAD dataset, five (ALDOA, PLK1, CD47, CENPC and TMOD3) of which were integrated into a ferroptosis-related gene signature to calculate the risk score of LUAD samples, showing a significant correlation with the abundance of immune cell infiltration and the immune score. Molecular docking showed the binding activity of natural active compound quercetin to target proteins ALDOA and CD47, as well as the binding activity of aristolochic acid to PLK1 protein and TMOD3 protein.

CONCLUSIONS

In the present study, a ferroptosis-related gene signature with predictive value for LUAD prognosis was constructed, in which the gene was a potential therapeutic target for LUAD. Quercetin and aristolochic acid were potential candidates for inhibiting these targets by directly binding to them and showing high affinity and strong stability.

Quantitative visualization of myocardial ischemia-reperfusion-induced cardiac lesions via ferroptosis magnetic particle imaging

Myocardial ischemia-reperfusion (MI/R) injury is a complication in vascular reperfusion therapy for MI, occurring in approximately 60% of patients. Ferroptosis is an important process in the development of MI/R cardiac lesions. Transferrin receptor 1 (TfR1), a marker of ferroptosis, corresponds to the changes in MI/R cardiac lesions and is expected to be a biomarker for detecting MI/R-induced ferroptosis. However, the noninvasive in vivo visualization of ferroptosis in MI/R is a big challenge. Thus, this study aimed to develop a novel multimodal imaging platform to identify markers of MI/R cardiac lesions in vivo through targeting TfR1. Methods: Magnetic particle imaging (MPI) modality for ferroptosis based on superparamagnetic cubic-iron oxide nanoparticles (SCIO NPs), named feMPI, has been developed. FeMPI used TfR1 as a typical biomarker. The feMPI probe (SCIO-ICG-CRT-CPPs NPs, CCI NPs) consists of SCIO NPs, TfR1-targeting peptides (CRT), cell-penetrating peptides (CPPs), and indocyanine green (ICG). The specificity and sensitivity of CCI NPs in the MI/R mouse model were evaluated by MPI, magnetic resonance imaging (MRI), and near-infrared (NIR) fluorescent imaging. Results: The intensity of the MPI signal correlates linearly with the percentage of infarct area in MI/R stained by TTC, enabling a quantitative assessment of the extent of cardiac lesions. Notably, these findings are consistent with the standard clinical biochemical indicators in MI/R within the first 24 h. FeMPI detects cardiac injury approximately 48 h prior to the current clinical imaging detection methods of MI/R. Conclusion: The feMPI strategy can be a powerful tool for studying the process of MI/R-induced ferroptosis in vivo, providing clues for molecular imaging and drug development of ferroptosis-related treatments.

Hypoxia improves self-renew and migration of urine-derived stem cells by upregulating autophagy and mitochondrial function through ERK signal pathway

Urine-derived stem cells (USCs) are autologous stem cells with self-renewal ability and multi-lineage differentiation potential. Our previous studies have shown that hypoxia preconditioning can improve self-renewal and migration abilities of USCs by up-regulating autophagy. The purpose of this study was to investigate the specific mechanism by which hypoxia treatment promotes the biological function of USCs. We found that hypoxia treatment upregulated the expression of phosphralated ERK protein without affecting the expression of total ERK protein. Inhibiting ERK signaling with the PD98059 inhibitor decreased cell proliferation, migration and colony formation during hypoxia treatment. Hypoxia increased ATP production, mitochondrial membrane potential and mt-DNA copy number, which were reversed by inhibiting the ERK signal. Additionally, the number of autophagosomes and autophagic lysosomes was significantly lower in PD98059 group than in the hypoxia group. PD98059 treatment inhibited the up-regulation of autophagy related proteins induced by hypoxia. Therefore, this study suggests that hypoxia improves the self-renewal and migration abilities of USCs by upregulating autophagy and mitochondrial function through ERK signaling pathway. This finding may provide a new therapeutic mechanism for hypoxia pretreated USCs as a source of stem cell transplantation.

Canagliflozin reduces chemoresistance in hepatocellular carcinoma through PKM2-c-Myc complex-mediated glutamine starvation

Cisplatin (CPT) is one of the standard treatments for hepatocellular carcinoma (HCC). However, its use is limits as a monotherapy due to drug resistance, and the underlying mechanism remains unclear. To solve this problem, we tried using canagliflozin (CANA), a clinical drug for diabetes, to reduce chemoresistance to CPT, and the result showed that CANA could vigorously inhibit cell proliferation and migration independent of the original target SGLT2. Mechanistically, CANA reduced aerobic glycolysis in HCC by targeting PKM2. The downregulated PKM2 directly bound to the transcription factor c-Myc in the cytoplasm to form a complex, which upregulated the level of phosphorylated c-Myc Thr58 and promoted the ubiquitination and degradation of c-Myc. Decreased c-Myc reduced the expression of GLS1, a key enzyme in glutamine metabolism, leading to impaired glutamine utilization. Finally, intracellular glutamine starvation induced ferroptosis and sensitized HCC to CPT. In conclusion, our study showed that CANA re-sensitized HCC to CPT by inducing ferroptosis through dual effects on glycolysis and glutamine metabolism. This is a novel mechanism to increase chemosensitivity, which may provide compatible chemotherapy drugs for HCC.

Prolyl 4-hydroxylase subunit beta (P4HB) could serve as a prognostic and radiosensitivity biomarker for prostate cancer patients

BACKGROUND

Prolyl 4-hydroxylase subunit beta (P4HB) has been reported as a suppressor in ferroptosis. However, no known empirical research has focused on exploring relationships between P4HB and prostate cancer (PCa). In this research, we initially examine the function of P4HB in PCa by thorough analysis of numerous databases and proliferation experiment.

METHODS

We analyzed the correlations of P4HB expression with prognosis, clinical features, mutation genes, tumor heterogeneity, stemness, tumor immune microenvironment and PCa cells using multiple databases and in vitro experiment with R 3.6.3 software and its suitable packages.

RESULTS

P4HB was significantly upregulated in tumor tissues compared to normal tissues and was closely related to biochemical recurrence-free survival. In terms of clinical correlations, we found that higher P4HB expression was significantly related to older age, higher Gleason score, advanced T stage and residual tumor. Surprisingly, P4HB had highly diagnostic accuracy of radiotherapy resistance (AUC 0.938). TGF beta signaling pathway and dorso ventral axis formation were upregulated in the group of low-expression P4HB. For tumor stemness, P4HB expression was positively related to EREG.EXPss and RNAss, but was negatively associated with ENHss and DNAss with statistical significance. For tumor heterogeneity, P4HB expression was positively related to MATH, but was negatively associated with tumor ploidy and microsatellite instability. For the overall assessment of TME, we observed that P4HB expression was negatively associated with all parameters, including B cells, CD4+ T cells, CD8+ T cells, neutrophils, macrophages, dendritic cells, stromal score, immune score and ESTIMATE score. Spearman analysis showed that P4HB expression was negatively related to TIDE score with statistical significance. In vitro experiment, RT-qPCR and western blot showed that three siRNAs of P4HB were effective on the knockdown of P4HB expression. Furthermore, we observed that the downregulation of P4HB had significant influence on the cell proliferation of six PCa cell lines, including LNCap, C4-2, C4-2B, PC3, DU145 and 22RV1 cells.

CONCLUSIONS

In this study, we found that P4HB might serve as a prognostic biomarker and predict radiotherapy resistance for PCa patients. Downregulation of P4HB expression could inhibit the cell proliferation of PCa cells.

Shikonin and cisplatin synergistically overcome cisplatin resistance of ovarian cancer by inducing ferroptosis via upregulation of HMOX1 to promote Fe2+ accumulation

BACKGROUND

Cisplatin-based chemotherapy often results in ovarian cancer (OC) chemical resistance and treatment failure. The combination of natural compounds with platinum-based agents is a new strategy for overcoming cisplatin resistance. At present, the synergistic effects and mechanism of combination of shikonin and cisplatin to overcome cisplatin resistance in OC are still unknown.

PURPOSE

This study was to evaluate the synergistic effects of shikonin and cisplatin on cisplatin-resistant OC cells and to assess the underlying molecular basis for these effects.

METHODS

Cell counting kit-8 assay, colony-formation assay, proteomic analysis, reactive oxygen species (ROS) detection, lipid peroxidation (LPO) detection, Fe²⁺ detection, western blot, and quantitative real-time reverse transcription PCR (qRT-PCR) were performed to evaluate the effects of shikonin and cisplatin on cisplatin-resistant OC cells. Underlying mechanisms of action were investigated in vitro using small molecule inhibitors and siRNA. In vivo, the effect of shikonin and cisplatin combination on tumor growth in BALB/c nude mice was evaluated, with tumor immunohistochemical (IHC) staining performed to detect ferroptosis-related proteins.

RESULTS

In vitro, shikonin and cisplatin were shown to synergistically reduce the viability of cisplatin-resistant OC cells. Proteomic results demonstrated that the combination of the two drugs induced a ferroptotic process, as evidenced by increased levels of ROS, LPO, and Fe²⁺, with downregulation of glutathione peroxidase 4 (GPX4). Heme oxygenase 1 (HMOX1) inhibition and siRNA interference attenuated the combined effect of the two drugs on cell viability. Accumulation of Fe²⁺ was attenuated by siRNA interference of HMOX1. In vivo, combination treatment significantly inhibited the growth of subcutaneous tumors in BALB/c nude mice and increased the expression of ferroptosis-related proteins in tumor tissue.

CONCLUSION

We report for the first time that the co-treatment of shikonin and cisplatin overcomes cisplatin resistance in OC through ferroptosis. Mechanistic analysis reveals the co-treatment induces ferroptosis through upregulation of HMOX1 that promotes Fe²⁺ accumulation.