The biological functions of N6-methyladenosine (m 6 A) RNA methylation are mainly dependent on the reader; however, its role in lung tumorigenesis remains unclear. Here, we have demonstrated that the m 6 A reader YT521-B homology domain containing 2 (YTHDC2) is frequently suppressed in lung adenocarcinoma (LUAD). Downregulation of YTHDC2 was associated with poor clinical outcome of LUAD. YTHDC2 decreased tumorigenesis in a spontaneous LUAD mouse model. Moreover, YTHDC2 exhibited antitumor activity in human LUAD cells. Mechanistically, YTHDC2, via its m 6 A-recognizing YTH domain, suppressed cystine uptake and blocked the downstream antioxidant program. Administration of cystine downstream antioxidants to pulmonary YTHDC2-overexpressing mice rescued lung tumorigenesis. Furthermore, solute carrier 7A11 (SLC7A11), the catalytic subunit of system X C − , was identified to be the direct target of YTHDC2. YTHDC2 destabilized SLC7A1 1 mRNA in an m 6 A-dependent manner because YTHDC2 preferentially bound to m 6 A-modified SLC7A1 1 mRNA and thereafter promoted its decay. Clinically, a large proportion of acinar LUAD subtype cases exhibited simultaneous YTHDC2 downregulation and SLC7A11 elevation. Patient-derived xenograft (PDX) mouse models generated from acinar LUAD showed sensitivity to system X C − inhibitors. Collectively, the promotion of cystine uptake via the suppression of YTHDC2 is critical for LUAD tumorigenesis, and blocking this process may benefit future treatment.

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Rationale: Ferroptosis, a newly identified form of regulated cell death, can be induced following the inhibition of cystine-glutamate antiporter system X C - because of the impaired uptake of cystine. However, the outcome following the accumulation of endogenous glutamate in lung adenocarcinoma (LUAD) has not yet been determined. Yes-associated protein (YAP) is sustained by the hexosamine biosynthesis pathway (HBP)-dependent O-linked beta-N-acetylglucosaminylation (O-GlcNAcylation), and glutamine-fructose-6-phosphate transaminase (GFPT1), the rate-limiting enzyme of the HBP, can be phosphorylated and inhibited by adenylyl cyclase (ADCY)-mediated activation of protein kinase A (PKA). However, whether accumulated endogenous glutamate determines ferroptosis sensitivity by influencing the ADCY/PKA/HBP/YAP axis in LUAD cells is not understood. Methods: Cell viability, cell death and the generation of lipid reactive oxygen species (ROS) and malondialdehyde (MDA) were measured to evaluate the responses to the induction of ferroptosis following the inhibition of system X C - . Tandem mass tags (TMTs) were employed to explore potential factors critical for the ferroptosis sensitivity of LUAD cells. Immunoblotting (IB) and quantitative RT-PCR (qPCR) were used to analyze protein and mRNA expression. Co-immunoprecipitation (co-IP) assays were performed to identify protein-protein interactions and posttranslational modifications. Metabolite levels were measured using the appropriate kits. Transcriptional regulation was evaluated using a luciferase reporter assay, chromatin immunoprecipitation (ChIP), and electrophoretic mobility shift assay (EMSA). Drug administration and limiting dilution cell transplantation were performed with cell-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models. The associations among clinical outcome, drug efficacy and ADCY10 expression were determined based on data from patients who underwent curative surgery and evaluated with patient-derived primary LUAD cells and tissues. Results: The accumulation of endogenous glutamate following system X C - inhibition has been shown to determine ferroptosis sensitivity by suppressing YAP in LUAD cells. YAP O-GlcNAcylation and expression cannot be sustained in LUAD cells upon impairment of GFPT1. Thus, Hippo pathway-like phosphorylation and ubiquitination of YAP are enhanced. ADCY10 acts as a key downstream target and diversifies the effects of glutamate on the PKA-dependent suppression of GFPT1. We also discovered that the protumorigenic and proferroptotic effects of ADCY10 are mediated separately. Advanced-stage LUADs with high ADCY10 expression are sensitive to ferroptosis. Moreover, LUAD cells with acquired therapy resistance are also prone to higher ADCY10 expression and are more likely to respond to ferroptosis. Finally, a varying degree of secondary labile iron ...

Ferroptosis is a new form of regulated cell death and closely related to cancer. However, the mechanism underlying the regulation of ferroptosis in lung adenocarcinoma (LUAD) remains unclear. IB, IHC and ELISA were performed to analyze protein expression. RT-qPCR was used to analyze mRNA expression. Cell viability, 3D cell growth, MDA, the generation of lipid ROS and the Fe 2+ concentration were measured to evaluate the responses to the induction of ferroptosis. Measurement of luciferase activity and ChIP were used to analyze the promoter activity regulated by the transcriptional regulator. Co-IP assays were performed to identify protein-protein interactions. In the present study, it was revealed that cAMP response element-binding protein (CREB) was highly expressed in LUAD, and knockdown of CREB inhibited cell viability and growth by promoting apoptosis-and ferroptosis-like cell death, concurrently. It was observed that CREB suppressed lipid peroxidation by binding the promoter region of glutathione peroxidase 4 (GPX4), and this binding could be enhanced by E1A binding protein P300 (EP300). The bZIP domain in CREB and the CBP/p300-HAT domain in EP300 were essential for CREB-EP300 binding in LUAD cells. Finally, it was revealed that CREB, GPX4, EP300 and 4-HNE were closely related to tumor size and stage, and tumors with a higher degree of malignancy were more likely to have a low degree of lipid peroxidation. Therefore, targeting this CREB/EP300/GPX4 axis may provide new strategies for treating LUAD.

Background Resistance to ferroptosis, a regulated cell death caused by iron‐dependent excessive accumulation of lipid peroxides, has recently been linked to lung adenocarcinoma (LUAD). Intracellular antioxidant systems are required for protection against ferroptosis. The purpose of the present study was to investigate whether and how extracellular system desensitizes LUAD cells to ferroptosis. Methods Established human lung fibroblasts MRC‐5, WI38, and human LUAD H1650, PC9, H1975, H358, A549, and H1299 cell lines, tumor and matched normal adjacent tissues of LUAD, and plasma from healthy individuals and LUAD patients were used in this study. Immunohistochemistry and immunoblotting were used to analyze protein expression, and quantitative reverse transcription‐PCR was used to analyze mRNA expression. Cell viability, cell death, and the lipid reactive oxygen species generation were measured to evaluate the responses to ferroptosis. Exosomes were observed using transmission electron microscope. The localization of arachidonic acid (AA) was detected using click chemistry labeling followed by confocal microscopy. Interactions between RNAs and proteins were detected using RNA pull‐down, RNA immunoprecipitation and photoactivatable ribonucleoside‐enhanced crosslinking and immunoprecipitation methods. Proteomic analysis was used to investigate RNA‐regulated proteins, and metabolomic analysis was performed to analyze metabolites. Cell‐derived xenograft, patient‐derived xenograft, cell‐implanted intrapulmonary LUAD mouse models and plasma/tissue specimens from LUAD patients were used to validate the molecular mechanism. Results Plasma exosome from LUAD patients specifically reduced lipid peroxidation and desensitized LUAD cells to ferroptosis. A potential explanation is that exosomal circRNA_101093 (cir93) maintained an elevation in intracellular cir93 in LUAD to modulate AA, a poly‐unsaturated fatty acid critical for ferroptosis‐associated increased peroxidation in the plasma membrane. Mechanistically, cir93 interacted with and increased fatty acid‐binding protein 3 (FABP3), which transported AA and facilitated its reaction with taurine. Thus, global AA was reduced, whereas N‐arachidonoyl taurine (NAT, the product of AA and taurine) was induced. Notably, the role of NAT in suppressing AA incorporation into the plasma membrane was also revealed. In pre‐clinical in vivo models, reducing exosome improved ferroptosis‐based treatment. Conclusion Exosome and cir93 are essential for desensitizing LUAD cells to ferroptosis, and blocking exosome may be helpful for future LUAD treatment.

Anaplastic thyroid cancer (ATC) is a highly lethal undifferentiated malignancy without reliable therapies. Retinoic acid (RA) has been employed to promote redifferentiation of thyroid cancers by increasing their I131 uptake and radio-sensitivity, but its effect(s) on ATCs has not yet been ascertained. Likewise, resveratrol induces cancer redifferentiation but, also in this case, its effects on ATCs remain unknown. These issues have been addresses in the current study using three human ATC cell lines (THJ-11T, THJ-16T, and THJ-21T) through multiple experimental approaches. The results reveal that RA exerts a small inhibitory effect on these cell lines. In comparison with normally cultured cells, the total cell number in resveratrol-treated THJ-16T and THJ-21T cultures significantly decreased (p < 0.05), and this effect was accompanied by reduced Cyclin D1 immuno-labeling, increased apoptotic fractions, and distinct caspase-3 activation. Resveratrol failed to inhibit growth but enhanced RA sensitivity of THJ-11T cells, suppressed peroxisome proliferator-activated receptor-β/δ (PPAR-β/δ), and upregulated cellular retinoic acid-binding protein 2 (CRABP2) and retinoic acid receptor beta (RAR-β) expression. Increased thyroglobulin (Tg) and E-cadherin levels and appearance of membranous E-cadherin were evidenced in resveratrol-treated THJ-11T cells. Our results demonstrate for the first time: (1) the therapeutic value of resveratrol by itself or in combination with RA in the management of ATCs, (2) the capacity of resveratrol to overcome RA resistance in ATC cells by reprogramming CRABP2/RAR- and fatty acid-binding protein 5 (FABP5)/PPAR-β/δ-mediated RA signaling, and (3) the redifferentiating potential of resveratrol in ATC cells.

Anaplastic thyroid carcinoma (ATC) is the most lethal thyroid malignancy without a reliable therapeutic agent. Resveratrol possesses cancer-suppressive effects, while its effect(s) on ATC cells remains unknown. Because oxidative damage caused by increased reactive oxygen species (ROS) is one of the therapeutic effects of anticancer drugs and oxidative stress-caused mitochondria swelling is observed in resveratrol-treated cancer cells, the oxidative statuses and their relevance with resveratrol sensitivities are elucidated using THJ-16T and THJ-11T ATC cells established from two human anaplastic thyroid carcinoma cases. The results revealed that resveratrol-treated THJ-16T rather than THJ-11T cells showed remarkable growth arrest and extensive apoptosis accompanied with the elevated ROS generation and the attenuated superoxide dismutase 2 (SOD2) and catalase (CAT) levels. Mitochondrial impairment and the enhanced caspase-9/caspase-3 activation are found only in resveratrol-sensitive THJ-16T cells. Treatment with the antioxidant N-acetylcysteine (NAC) partly attenuated resveratrol-induced ROS generation and apoptosis of THJ-16T cells. The levels of resveratrol metabolic enzymes (SULT1A1 and SULT1C2) in THJ-16T cells were lower than those in THJ-11T cells and therefore reversely related with resveratrol sensitivities of ATC cells. Our findings demonstrate the ability of resveratrol to increase ROS generation and oxidative-related cellular lesions in resveratrol-sensitive THJ-16T cells presumably through activating the ROS-mitochondrial signal pathway. The levels of SULTs and ROS may reflect the response manners of ATC cells to resveratrol.

Metabolite profiling plays a crucial role in drug discovery and development, and HPLC-Q-TOF has evolved into a powerful and effective high-resolution analytical tool for metabolite detection. However, traditional empirical identification is laborious and incomplete. This paper presents a systematic and comprehensive strategy for elucidating metabolite structures using software-assisted HPLC-Q-TOF that takes full advantage of data acquisition, data processing, and data mining technologies, especially for high-throughput metabolite screening. This strategy has been successfully applied in the study of magnoflorine metabolism based on our previous report of its poor bioavailability and drug-drug interactions. In this report, 23 metabolites of magnoflorine were tentatively identified with detailed fragmentation pathways in rat biological samples (urine, feces, plasma, and various organs) after i.p. or i.g. administration, and for most of these metabolites, the metabolic sites were determined. The phase I biotransformations of magnoflorine (M1-M7, M10-M14) consist of demethylation, dehydrogenation, hydroxylation, methylene to ketone transformation, N-ring opening, and dehydroxylation. The phase II biotransformations (M8, M9, and M15-M23) consist of methylation, acetylation, glucuronidation, and N-acetylcysteine conjugation. The results indicate that the extensive metabolism and wide tissue distribution of magnoflorine and its metabolites may partly contribute to its poor bioavailability and drug-drug interaction, and i.p. administration should thus be a suitable approach for isolating magnoflorine metabolites. In summary, this strategy could provide an efficient, rapid, and reliable method for the structural characterization of drug metabolites and may be applicable for general Q-TOF users.