TRIM21 and PHLDA3 negatively regulate the crosstalk between the PI3K/AKT pathway and PPP metabolism

Amylin inhibits gastric cancer progression by targeting CCN1 and affecting the PI3K/AKT signalling pathway

METHODS

This study used a combination of in vitro and in vivo experiments to investigate the role of amylin in the progression of GC. The expression of amylin in GC and its clinical correlation were evaluated using 38 pairs of GC and healthy human clinical samples. In vitro studies, human GC cell lines were treated with amylin to evaluate the effects of amylin on the proliferation, apoptosis and migration of GC cells. In in vivo studies, xenograft mouse models were established by subcutaneous injection of GC cells into nude mice, followed by treatment with amylin to assess tumor growth. Finally, Next-Generation Sequencing Technology (RNA-seq) was used to explore the potential mechanism of amylin on GC.

RESULTS

We found that amylin expression was reduced in GC compared to adjacent normal gastric tissues and that elevated amylin expression was negatively correlated with adverse pathological factors (p < 0.05). Additionally, we demonstrated that amylin impeded the growth, invasion, migration, and colony formation of GC cells and suppressed the epithelial-to-mesenchymal transformation of these cells (p < 0.05). Tumour xenograft model experiments confirmed the tumour-suppressive effect of amylin in subcutaneous tumours in nude mice (p < 0.05). Transcriptome sequencing (RNA-seq) revealed that amylin significantly down-regulated CCN1 gene expression in GC cells (p < 0.001). Further intervention targeting CCN1 verified its significance as a target of amylin's anti-carcinogenic function in GC. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that amylin exerted its oncogenic effects by inhibiting the PI3K/Akt signalling pathway (p < 0.05).

CONCLUSIONS

Our findings demonstrate that amylin plays a crucial role in suppressing gastric cancer progression by targeting CCN1 and inhibiting the PI3K/Akt signalling pathway. These results suggest that amylin could serve as a potential therapeutic agent for GC treatment.

Estrogen mitigates ischemia-reperfusion injury by inhibiting cardiomyocyte ferroptosis through the downregulation of PHLDA3 expression

Ferroptosis represents a significant target for mitigating myocardial ischemia-reperfusion (I/R) injury. Existing literature indicates that estrogen (17β-estradiol, E2) can alleviate such injuries through various pathways. However, the specific mechanisms by which E2 may confer protection against myocardial I/R injury through the inhibition of ferroptosis remain to be fully elucidated. This study employed a mouse model of left anterior descending coronary artery ligation to investigate the protective effects of E2 on myocardial I/R injury, with a particular focus on its inhibitory effects on ferroptosis and PHLDA3 in both hypoxia-reoxygenation (H/R) and I/R models. A bioinformatics analysis was conducted to evaluate the impact of estrogen receptor GPER knockout on PHLDA3 expression and ferroptosis. Loss-of-function approaches were employed to elucidate the role of PHLDA3 in ferroptosis during myocardial I/R injury. Our findings demonstrate that E2 can ameliorate myocardial I/R injury, primarily by inhibiting ferroptosis. Notably, PHLDA3 expression levels were significantly elevated during ischemia-reperfusion events; however, E2 was observed to suppress this expression. Bioinformatics analysis indicated that PHLDA3 levels increased following GPER knockdown, and the inhibitory effect of E2 on PHLDA3 expression could be partially reversed by GPER inhibitors (G15) in animal models. Furthermore, the suppression of PHLDA3 reduced ferroptosis and mitigated the severity of myocardial I/R injury. Utilizing mass spectrometry and co-immunoprecipitation methodologies, we have elucidated a potential mechanism in which PHLDA3 directly binds to and interacts with proteins involved in the process of ferroptosis. Our findings demonstrate that E2 effectively suppresses ferroptosis and mitigates myocardial I/R injury by downregulating PHLDA3 expression through the activation of the GPER receptor.

RETRACTED: MiR-375 impairs breast cancer cell stemness by targeting the KLF5/G6PD signaling axis

Recurrence of breast cancer may be due to the presence of breast cancer stem cells (BCSC). Abnormal tumor cell growth is closely associated with increased reactive oxygen species (ROS) and disruption of redox homeostasis, and BCSCs exhibit low levels of ROS. The detailed mechanism between the low levels of ROS in BCSCs and their maintenance of stemness characteristics has not been reported. A growing number of studies have shown that tumor development is often accompanied by metabolic reprogramming, which is an important hallmark of tumor cells. As the first rate-limiting enzyme of pentose phosphate pathway (PPP), the expression of G6PD is precisely regulated in tumor cells, and there is a certain correlation between PPP and BCSCs. MiR-375 has been shown to inhibit stem cell-like properties in breast cancer, but the exact mechanism is not clear. Here, KLF5, as a transcription factor, was identified to bind to the promoter of G6PD to promote its expression, whereas miR-375 inhibited the expression of KLF5 by binding to the 3'UTR region of KLF5 mRNA and thus reduced the expression of G6PD expression, inhibits PPP to reduce NADPH, and increases ROS levels in breast cancer cells, thereby weakening breast cancer cell stemness. Our study reveals the specific mechanism by which miR-375 targets the KLF5/G6PD signaling axis to diminish the stemness of breast cancer cells, providing a therapeutic strategy against BCSCs.

Friend or foe of tripartite motif-containing protein 21 in cardiovascular disease: A review

As an E3 ubiquitin ligase and an Fc receptor, tripartite motif-containing protein 21 (TRIM21) plays a crucial role in immune defense, signal transduction, and cellular regulation. TRIM21 is widely expressed in various tissues, but it is particularly abundant in cardiovascular tissues and is involved in the pathogenesis of various cardiovascular diseases (CVDs). However, although TRIM21 is involved in the regulation of several key molecular pathways in the immune system, its specific role in CVD remains unclear. In this review, we comprehensively summarize the regulatory role of TRIM21 in signaling pathways and discuss the function of TRIM21 in CVD, to provide a systematic understanding of this important protein in CVD and offer insights for further research into the pathogenesis of CVD and its potential applications.

Exploring the molecular mechanisms underlying intervertebral disc degeneration by analysing multiple datasets

The purpose of this study was to explore the genetic characteristics and immune cell infiltration related to intervertebral disc degeneration through multidataset analysis, predict potential therapeutic drugs, and provide a theoretical basis for clinical treatment. The gene expression profile data of the GSE70362, GSE186542, and GSE245147 datasets were downloaded from the Gene Expression Omnibus (GEO) database, and the hub genes were identified through differentially expressed gene analysis, Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) functional annotation and Mendelian randomization analysis were performed. Hub genes and immune cells were identified. Infiltration status was determined through GSEA and GSVA to clarify the specific signalling pathways associated with key genes and explore the potential molecular mechanisms by which key genes affect disease progression. The key genes were reversely predicted using miRNA grid construction and transcription factor regulation, and genes related to disease regulation were obtained from the GeneCards database. Finally, the differentially expressed genes were used for drug prediction through the Connectivity Map database to identify potential drugs for the treatment of intervertebral disc degeneration. The feasibility of the predicted drugs was tested by molecular docking technology. Real-time quantitative PCR was used to confirm the expression of key genes in the tissue samples.A total of 126 differentially expressed genes were identified in the GEO database, and 4 differentially expressed hub genes (COL6A2, DCXR, GLRX, and PDGFRB) were identified through bioinformatics methods. Immune infiltration analysis revealed that NK cells, macrophages, and eosinophils were activated during IVDD, whereas mast cells and T cells were suppressed. GO and KEGG analyses revealed that key genes are involved in the development of this disease through signalling pathways such as the glycolysis pathway, the oxidative phosphorylation pathway, the cholesterol regulatory pathway, and the haem metabolism pathway. Analysis of the constructed miRNA grid revealed that key genes are jointly regulated by multiple transcription factors, among which the most important motif is cisbp_M5578. Disease regulation-related genes were obtained through the GeneCards database, analysis of the correlation with key genes was performed, and the expression levels of the two mRNA and miRNA were significantly correlated. Finally, drug prediction performed through the Connectivity Map database revealed that drugs such as Abt-751, LY-2183240, podophyllotoxin, and vindesine can alleviate or even reverse the disease state. Finally, we collected 10 IVDD and 10 healthy disc tissue samples, and the RT‒qPCR results were consistent with the bioinformatics results. We identified COL6A2, DCXR, GLRX, and PDGFRB as key genes involved in IVDD. In addition, drugs such as Abt-751 are expected to control and reverse the progression of the disease. In the future, these key genes and predicted drugs may provide new directions for further mechanistic studies as well as new therapies for IVDD patients.

ENC1 Promotes the Malignant Progression and Metastasis by Suppressing TRIM21 Mediated Vimentin Degradation in Wilms Tumor

Ectodermal neural cortex 1 (ENC1) is significantly upregulated in various cancers and shows a positive correlation with poor prognosis and advanced clinical stages, such as colorectal cancer, endometrial cancer and breast cancer. However, the role of ENC1 in Wilms tumor (WT) has not been previously reported. In this study, we conducted several in vitro functional experiments and established xenograft models to confirm the oncogenic potential of ENC1. The binding proteins of ENC1 were identified through co-immunoprecipitation and mass spectrometry to screen the mechanism of malignant progression. Further analysis elucidated the mechanism by which ENC1 promotes tumorigenesis. The results demonstrated that ENC1 was significantly overexpressed in tumor and recurrence samples, with elevated ENC1 expression showing a significant negative correlation with both overall survival and recurrence-free survival of patients. Functionally, the role of ENC1 in tumor oncogenicity was elucidated through the assessment of tumor cell proliferation, migration, and invasion capabilities. Mechanistically, through immunoprecipitation and mass spectrometry, we identified Vimentin as an interacting protein of ENC1. ENC1 competed with the E3 ubiquitin ligase TRIM21 for Vimentin binding, thereby reducing the ubiquitination level of Vimentin and enhancing its protein stability. In conclusion, this study demonstrates that ENC1 functions as a novel oncogenic target for Wilms tumor by disrupting TRIM21-mediated ubiquitination of Vimentin, which presents novel insights for the treatment of Wilms tumor and the development of prognostic markers.

TRIM21-mediated METTL3 degradation promotes PDAC ferroptosis and enhances the efficacy of Anti-PD-1 immunotherapy

Pancreatic cancer remains the most lethal human malignancy with limited clinical benefits from currently available anticancer treatments. Ferroptosis has recently attracted great attention as a potential antineoplastic strategy. However, the study of ferroptosis in PDAC remains insufficient. This study revealed that Methyltransferase like 3 (METTL3), as a key oncogenic factor, is frequently upregulated and inhibits ferroptosis by stabilizing SLC7A11 mRNA in PDAC. In addition, we identified a novel post-translational modification of METTL3 and characterized specific regulatory mechanisms of METTL3 protein degradation. The E3 ligase TRIM21 mediated K48-linked polyubiquitination of METTL3 at the K459 site, leading to the proteasomal degradation of METTL3, which prevented tumor progression by promoting ferroptosis. Interestingly, the TRIM21-METTL3 axics mediated ferroptosis effectively increased the expression of immune checkpoint PD-L1 and strengthened antitumor immunity in pancreatic cancer. Together, our findings first elucidated the detailed molecular mechanism of METTL3 degradation and revealed the pivotal role of the TRIM21-METTL3 axis in regulating ferroptosis and antitumor immunity, which may serve as a potential target for pancreatic cancer treatment.

The mechanism of egg production improvement in laying hens before and after molting revealed by transcriptome and metabolome integration

The objective of this research was to examine the effects and underlying mechanisms of forced molting on the laying rate of hens. A total of ninety 500-day-old laying hens were randomly assigned to three groups: a control group (CK), a starvation group (SG), and a recovery group (RG). The study evaluated follicular development in hens and measured the expression levels of antioxidant, lipid, and inflammatory factors in their serum. Additionally, transcriptomic and metabolomic analyses were performed to assess the effects of forced molting on gene expression and metabolic profiles in hens. The findings indicated that forced molting led to an increase of laying rates, a reduction in follicular closure, and a significant rise in the levels of antioxidant enzymes such as GSH, CAT, and SOD, alongside a decrease in MDA levels. Furthermore, there were significant reductions in the blood lipid levels of LDL, HDL, TC, and TG. Additionally, there were notable differences in the inflammatory markers TNF-α, IL-1, and IL-6. The transcriptomic and metabolomic data revealed that forced molting influenced the activation of the PI3K-AKT and mTOR signaling pathways, affecting fatty acid metabolism in laying hens and modulating the expression of associated genes. In conclusion, this study demonstrates that forced molting is an effective strategy for enhancing the laying rate of hens. Furthermore, it provides a valuable theoretical framework for advancing breeding practices aimed at improving egg production.

Neuritin improves cognitive impairments in APP/PS1 Alzheimer's disease mice model by mitigating neuronal ferroptosis via PI3K/Akt activation

The neurotrophic factor Neuritin is known to enhance cognitive capacity and to mitigate synaptic impairments in the APP/PS1 Alzheimer's disease (AD) mouse model, suggesting therapeutic potential for clinical treatment. However, the core molecular mechanisms remain elusive. Ferroptosis, a form of programmed cell death linked to iron dysregulation and oxidative stress, contributes to neurodegeneration in AD in part by accelerating amyloid-β deposition and neurofibrillary tangle formation. Here we examined if Neuritin can mitigate cognitive decline and neural degeneration in AD model mice by suppressing ferroptosis. Age-dependent cognitive decline was associated with Neuritin downregulation and increased ferroptosis in the hippocampus. Intracerebroventricular injection of exogenous Neuritin mitigated spatial and fear learning deficits as well as neural oxidative stress, apoptosis, and ferroptosis in the hippocampus without causing deleterious side effects. Neuritin injection also upregulated the activity of NAD+ kinase (NADK), the enzyme responsible for converting NAD to anti-ferroptotic NADPH, in the hippocampus of AD mice as well as in cultured hippocampal neurons. Reduced Neuritin expression in the hippocampus AD mice was associated with reduced phosphorylation (activation) of Akt (p-Akt), and Neuritin administration enhanced p-Akt expression in both HT22 cells and AD model mice. Conversely, blocking the PI3K/Akt pathway in HT22 cells reversed the Neuritin-induced increase in NADK activity and reduction in ferroptosis, indicating that Neuritin protects neurons from AD-induced damage by enhancing NADK activity through the PI3K/Akt pathway. Collectively, our results support Neuritin upregulation as a potential therapeutic strategy for early-phase AD.

Current and future therapies for small cell lung carcinoma

Small cell lung cancer (SCLC) is an aggressive malignancy characterized by rapid proliferation and high metastatic potential. It is characterized by universal inactivation of and RB1, overexpression of the MYC family and dysregulation of multiple oncogenic signaling pathways. Among different patients, SCLCs are similar at the genetic level but exhibit significant heterogeneity at the molecular level. The classification of SCLC has evolved from a simple neuroendocrine (NE)/non-neuroendocrine (non-NE) classification system to a transcription factor-based molecular subtype system; lineage plasticity adds further complexity and poses challenges for therapeutic development. While SCLC is initially sensitive to platinum-based chemotherapy, resistance develops rapidly, leading to a dismal prognosis. Various antibodies, including PD-1/PD-L1 inhibitors and antibody‒drug conjugates, have been introduced into clinical practice or are being evaluated in clinical trials. However, their therapeutic benefits for SCLC patients remain limited. This review summarizes SCLC carcinogenic mechanisms, tumor heterogeneity, and the immune microenvironment of SCLC, with a focus on recent advances in metastasis and resistance mechanisms. Additionally, the corresponding clinical progress in tackling these challenges is discussed.

Chaetocin, a Natural Inhibitor of Transketolase, Suppresses the Non-Oxidative Pentose Phosphate Pathway and Inhibits the Growth of Drug-Resistant Non-Small Cell Lung Cancer

Worldwide, lung cancer is the most common cause of cancer-related death, which is made worse by the development of drug resistance during treatment. It is urgent to develop new therapeutic methods and small molecule drugs for tumor resistance. Chaetocin, extracted from Chaetomium minutum, is a natural compound with good antitumor activity. However, there are few studies on its tumor resistance. In this paper, firstly, chaetotocin significantly inhibited the viability and migration of cisplatin-resistant non-small cell lung cancer (NSCLC) cells and inhibited the xenograft growth of nude mice. Chaetocin at 4 mg/kg significantly inhibited A549/DDP xenograft growth with an inhibition rate of 70.43%. Subsequently, the underlying mechanism behind the actions of chaetocin was explored. It was discovered that chaetocin can inhibit transketolase (TKT), thereby inhibiting the growth of NSCLC cells and inducing cell death. Compared with cisplatin-sensitive cells, a lower concentration of chaetocin can inhibit cisplatin-resistance cell viability and migration. Mechanistically, TKT was identified as a potential target for chaetocin. The KD value of the interaction between chaetocin and TKT was 63.2 μM. An amount of 0.2 μM chaetocin may suppress the enzyme activity and expression level of TKT. We found the TKT expression is higher in cisplatin-resistant cells, which further explains why these cells were more vulnerable to chaetocin in terms of cell phenotype. Additionally, the muti-omics analysis and RNA interference suggested that chaetocin can inhibit the PI3K/Akt signaling pathway through TKT. In conclusion, chaetocin could directly bind to TKT, inhibiting its enzyme activity and expression, which interfered with intracellular metabolism and oxidation-reduction balance, and then regulated the PI3K/Akt signaling pathway to inhibit the growth of NSCLC and induce apoptosis.

METTL3 confers oxaliplatin resistance through the activation of G6PD-enhanced pentose phosphate pathway in hepatocellular carcinoma

Oxaliplatin-based therapeutics is a widely used treatment approach for hepatocellular carcinoma (HCC) patients; however, drug resistance poses a significant clinical challenge. Epigenetic modifications have been implicated in the development of drug resistance. In our study, employing siRNA library screening, we identified that silencing the m6A writer METTL3 significantly enhanced the sensitivity to oxaliplatin in both in vivo and in vitro HCC models. Further investigations through combined RNA-seq and non-targeted metabolomics analysis revealed that silencing METTL3 impeded the pentose phosphate pathway (PPP), leading to a reduction in NADPH and nucleotide precursors. This disruption induced DNA damage, decreased DNA synthesis, and ultimately resulted in cell cycle arrest. Mechanistically, METTL3 was found to modify E3 ligase TRIM21 near the 3'UTR with N6-methyladenosine, leading to reduced RNA stability upon recognition by YTHDF2. TRIM21, in turn, facilitated the degradation of the rate-limiting enzyme of PPP, G6PD, through the ubiquitination-proteasome pathway. Importantly, high expression of METTL3 was significantly associated with adverse prognosis and oxaliplatin resistance in HCC patients. Notably, treatment with the specific METTL3 inhibitor, STM2457, significantly improved the efficacy of oxaliplatin. These findings underscore the critical role of the METTL3/TRIM21/G6PD axis in driving oxaliplatin resistance and present a promising strategy to overcome chemoresistance in HCC.

IRGM Inhibits the AKT/mTOR Signaling Pathway by Interacting with TRIM21 to Alleviate Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) is a severe complication of sepsis, and its underlying pathological mechanisms remain poorly understood. This study aims to investigate the role and mechanisms by which IRGM mediates autophagy through the regulation of the AKT/mTOR signaling pathway in sepsis-induced ALI. Initially, a sepsis-induced ALI mouse model was established using cecal ligation and puncture (CLP). Our results demonstrated that Irgm1 expression was significantly upregulated in the ALI model. Subsequently, Irgm1 was knocked down in vivo using AAV vectors, and changes in ALI symptoms were assessed. In vitro, a sepsis-induced ALI cell model was generated by stimulating A549 cells with lipopolysaccharide (LPS). The effects of IRGM overexpression on autophagy and apoptosis were evaluated, and its impact on the AKT/mTOR signaling pathway was analyzed. Furthermore, mass spectrometry and co-immunoprecipitation (COIP) experiments were conducted to explore the interaction between IRGM and TRIM21. In vivo results showed that Irgm1 knockout exacerbated CLP-induced ALI, as evidenced by a significant reduction in autophagic activity, increased apoptosis, and aberrant activation of the AKT/mTOR pathway. Further cellular experiments suggested that IRGM may enhance autophagy by inhibiting the AKT/mTOR signaling pathway, thereby attenuating LPS-induced cell damage. Additionally, COIP experiments revealed that IRGM interacts with TRIM21 to inhibit AKT/mTOR pathway activation, thereby promoting autophagy and mitigating sepsis-induced ALI. In conclusion, IRGM regulates autophagy through the AKT/mTOR signaling pathway and exerts protective effects in sepsis-induced ALI, suggesting that it may serve as a potential therapeutic target for sepsis-related ALI.

The Mechanism of TRIM21 Inhibiting the Invasion and Migration of ccRCC by Stabilizing ASS1

Clear cell renal cell carcinoma (ccRCC) is characterized by its aggressive invasion and metastasis, presenting significant clinical challenges. Gaining insights into the molecular mechanisms underlying its progression is crucial for the development of effective therapeutic strategies. Addressing a critical knowledge gap in understanding ccRCC tumorigenesis, this study aims to elucidate the expression patterns of TRIM21 in ccRCC, unravel its impact on ccRCC patient prognosis, and investigate the regulatory role of TRIM21 in ASS1 expression and urea cycle dysregulation within the context of ccRCC. The results demonstrate that TRIM21 is downregulated in ccRCC, and low expression of TRIM21 predicts an unfavorable prognosis for ccRCC patients. Furthermore, the upregulation of TRIM21 can inhibit the migration and invasion of ccRCC cells by regulating the ubiquitination modification of ASS1. This not only expands the functional role of TRIM21 in ccRCC tumorigenesis but also demonstrates its ability to reverse urea cycle dysregulation through stabilizing ASS1 expression. Specifically, abnormal downregulation of TRIM21 in ccRCC reduces K63 ubiquitination modification of ASS1, leading to decreased stability of the ASS1 protein, aggravated urea cycle dysregulation, and facilitated migration and invasion of ccRCC cells. Additionally, reduction in ASS1 reverses the depressed migration and invasion caused by overexpression of TRIM21 in ccRCC cells. In summary, our findings contribute to a deeper understanding of the functional role played by TRIM21 in ccRCC progression, pinpoint a unique and novel regulatory mechanism involving ectopic downregulation-mediated ASS1 ubiquitination modification and urea cycle dysfunction during ccRCC progression, and provide fresh insights for further investigation into the pathogenesis and metabolic reprogramming associated with ccRCC.

FBXW7 metabolic reprogramming inhibits the development of colon cancer by down-regulating the activity of arginine/mToR pathways

FBXW7 is a tumor suppressor gene that regulates metabolism and is associated with the onset and progression of colorectal cancer (CRC)), however, the precise mechanism whereby FBXW7 participates in the metabolic reprogramming of CRC remains unclear. Here, the research aims to reveal the association between the expression of FBXW7 and clinical variables and to investigate the molecular mechanism by which FBXW7 plays a critical role in the development of CRC. The clinical importance of FBXW7 in CRC was determined by immunohistochemistry. Non-targeted metabolomics was utilized to explore the role of FBXW7 in the metabolic regulation of CRC. Low expression of FBXW7 was associated with poor prognosis in individuals with CRC, both at the mRNA and protein levels. FBXW7 over-expression inhibited CRC cell growth, colony formation, migration, and invasion. Non-targeted metabolomics unveiled that FBXW7 over-expression directly caused the deprivation of arginine which led to downmodulation of mTOR signaling pathway; meanwhile, FBXW7-related metabolites were primarily concentrated in the mTOR signaling pathway. In summary, the research identified a novel mechanism of action of FBXW7 in CRC. The research findings provide a theoretical foundation for the prognostic prediction and therapeutic planning of CRC based on metabolic reprogramming.

Ubiquitination Enzymes in Cancer, Cancer Immune Evasion, and Potential Therapeutic Opportunities

Ubiquitination is cells' second most abundant posttranslational protein modification after phosphorylation. The ubiquitin-proteasome system (UPS) is critical in maintaining essential life processes such as cell cycle control, DNA damage repair, and apoptosis. Mutations in ubiquitination pathway genes are strongly linked to the development and spread of multiple cancers since several of the UPS family members possess oncogenic or tumor suppressor activities. This comprehensive review delves into understanding the ubiquitin code, shedding light on its role in cancer cell biology and immune evasion. Furthermore, we highlighted recent advances in the field for targeting the UPS pathway members for effective therapeutic intervention against human cancers. We also discussed the recent update on small-molecule inhibitors and PROTACs and their progress in preclinical and clinical trials.

Reprogramming of Glucose Metabolism for Revisiting Hepatocellular Carcinoma Resistance to Transcatheter Hepatic Arterial Chemoembolization

Hepatocellular carcinoma (HCC) is recognized globally as one of the most lethal tumors, presenting a significant menace to patients' lives owing to its exceptional aggressiveness and tendency to recur. Transcatheter hepatic arterial chemoembolization (TACE) therapy, as a first-line treatment option for patients with advanced HCC, has been proven effective. However, it is disheartening that nearly 40 % of patients exhibit resistance to this therapy. Consequently, this review delves into the metabolic aspects of glucose metabolism to explore the underlying mechanisms behind TACE treatment resistance and to propose potentially fruitful therapeutic strategies. The ultimate objective is to present novel insights for the development of personalized treatment methods targeting HCC.

The hepatic clock synergizes with HIF-1α to regulate nucleotide availability during liver damage repair

Nucleotide availability is crucial for DNA replication and repair; however, the coordinating mechanisms in vivo remain unclear. Here, we show that the circadian clock in the liver controls the activity of the pentose phosphate pathway (PPP) to support de novo nucleotide biosynthesis for DNA synthesis demands. We demonstrate that disrupting the hepatic clock by genetic manipulation or mistimed feeding impairs PPP activity in male mice, leading to nucleotide imbalance. Such defects not only elicit DNA replication stress to limit liver regeneration after resection but also allow genotoxin-induced hepatocyte senescence and STING signalling-dependent inflammation. Mechanistically, the molecular clock activator BMAL1 synergizes with hypoxia-inducible factor-1α (HIF-1α) to regulate the transcription of the PPP rate-limiting enzyme glucose-6-phosphate dehydrogenase (G6PD), which is enhanced during liver regeneration. Overexpressing G6PD restores the compromised regenerative capacity of the BMAL1- or HIF-1α-deficient liver. Moreover, boosting G6PD expression genetically or through preoperative intermittent fasting potently facilitates liver repair in normal mice. Hence, our findings highlight the physiological importance of the hepatic clock and suggest a promising pro-regenerative strategy.

CITED2 Mediates Metabolic Reprogramming in Renal Tubular Epithelial Cells via the AKT Signaling Pathway to Induce Sepsis-Associated Acute Kidney Injury

Background

Sepsis-associated acute kidney injury (S-AKI) is a prevalent and severe clinical complication in intensive care units (ICUs) and is associated with high mortality and poor prognosis. The dysfunction of renal tubular epithelial cells (TECs), particularly through their metabolic reprogramming, plays a critical role in the onset and progression of S-AKI. CITED2 is shown to regulate a variety of cellular processes, but its specific impact on TECs metabolism and S-AKI pathogenesis remains unclear. The aim of this study was to investigate the role of CITED2 in the metabolic reprogramming of TECs and its effects on inflammation and kidney injury in S-AKI.

Material and Methods

The C57BL/6 mouse model of S-AKI was established using cecal ligation and puncture (CLP). We assessed the inflammatory responses, glucose metabolism and CITED2 expression in the kidneys of septic mice. Additionally, the effect of CITED2 on TECs metabolism and inflammation was evaluated using in vivo and in vitro models. CITED2 silencing and overexpression were employed to elucidate its regulatory role, focusing on the AKT signaling pathway.

Results

S-AKI causes structural and functional kidney damage, aggravated inflammatory responses, and dysregulated glucose metabolism, accompanied by increased expression of CITED2. CITED2 silencing attenuated TECs metabolic dysfunction and reduced inflammation, thereby protecting the kidney from injury. Conversely, CITED2 overexpression exacerbated TECs metabolic dysfunction, promoted inflammatory responses, and worsened kidney injury. Mechanistically, CITED2 regulates TEC metabolism through the AKT signaling pathway, promoting S-AKI-related inflammation and contributing to kidney injury.

Conclusion

CITED2 drives the metabolic reprogramming of TECs through the AKT signaling pathway, thereby aggravating the inflammatory response and leading to kidney injury, highlighting its critical role in S-AKI. Targeting CITED2 inhibition may represent a novel therapeutic approach for managing S-AKI.

Regulation of PI3K signaling in cancer metabolism and PI3K-targeting therapy

The phosphatidylinositol-3-kinase (PI3K) signaling plays a key role in various cellular functions and is frequently activated in cancer, making it an attractive therapeutic target. The PI3K signaling pathway influencing glucose metabolism, lipid synthesis, nucleotide production, and protein synthesis, all of which contribute to cancer cell proliferation and survival. It enhances glucose uptake through the activation of glucose transporters and glycolysis, while also promoting lipid synthesis via downstream factors like mTORC1. This pathway boosts nucleotide synthesis by regulating transcription factors like MYC, activating key enzymes for purine and pyrimidine production. Additionally, due to its essential role in cancer cell growth, the PI3K pathway is a key target for anticancer therapies. However, treatment using PI3K inhibitors alone has limitations, including drug resistance and significant side effects such as hyperglycemia, fatigue, and liver dysfunction. Clinical trials have led to the development of isoform-specific PI3K inhibitors to reduce toxicity. Combining PI3K inhibitors with other treatments, such as hormone therapy or surgery, may improve efficacy and minimize side effects. Further research is needed to fully understand the mechanisms of PI3K inhibitors and improve individualized treatment approaches. In this review, we introduce the characteristic of three classes of PI3Ks, discuss the regulation of cancer metabolism including the control of glucose uptake, glycolysis, de novo lipid synthesis, nucleotide synthesis and protein synthesis, and review the current statuses of different PI3K inhibitors therapy.

6-Phosphogluconate dehydrogenase promotes glycolysis and fatty acid synthesis by inhibiting the AMPK pathway in lung adenocarcinoma cells

Abnormal metabolism has emerged as a prominent hallmark of cancer and plays a pivotal role in carcinogenesis and progression of lung adenocarcinoma (LUAD). In this study, single-cell sequencing revealed that the metabolic enzyme 6-phosphogluconate dehydrogenase (PGD), which is a critical regulator of the pentose phosphate pathway (PPP), is significantly upregulated in the malignant epithelial cell subpopulation during malignant progression. However, the precise functional significance of PGD in LUAD and its underlying mechanisms remain elusive. Through the integration of TCGA database analysis and LUAD tissue microarray data, it was found that PGD expression was significantly upregulated in LUAD and closely correlated with a poor prognosis in LUAD patients. Moreover, in vitro and in vivo analyses demonstrated that PGD knockout and inhibition of its activity mitigated the proliferation, migration, and invasion of LUAD cells. Mechanistically, immunoprecipitation-mass spectrometry (IP-MS) revealed for the first time that IQGAP1 is a robust novel interacting protein of PGD. PGD decreased p-AMPK levels by competitively interacting with the IQ domain of the known AMPKα binding partner IQGAP1, which promoted glycolysis and fatty acid synthesis in LUAD cells. Furthermore, we demonstrated that the combination of Physcion (a PGD-specific inhibitor) and metformin (an AMPK agonist) could inhibit tumor growth more effectively both in vivo and in vitro. Collectively, these findings suggest that PGD is a potential prognostic biomarker and therapeutic target for LUAD.

The NRF2-CARM1 axis links glucose sensing to transcriptional and epigenetic regulation of the pentose phosphate pathway in gastric cancer

Cancer cells autonomously alter metabolic pathways in response to dynamic nutrient conditions in the microenvironment to maintain cell survival and proliferation. A better understanding of these adaptive alterations may reveal the vulnerabilities of cancer cells. Here, we demonstrate that coactivator-associated arginine methyltransferase 1 (CARM1) is frequently overexpressed in gastric cancer and predicts poor prognosis of patients with this cancer. Gastric cancer cells sense a reduced extracellular glucose content, leading to activation of nuclear factor erythroid 2-related factor 2 (NRF2). Subsequently, NRF2 mediates the classic antioxidant pathway to eliminate the accumulation of reactive oxygen species induced by low glucose. We found that NRF2 binds to the CARM1 promoter, upregulating its expression and triggering CARM1-mediated hypermethylation of histone H3 methylated at R arginine 17 (H3R17me2) in the glucose-6-phosphate dehydrogenase gene body. The upregulation of this dehydrogenase, driven by the H3R17me2 modification, redirects glucose carbon flux toward the pentose phosphate pathway. This redirection contributes to nucleotide synthesis (yielding nucleotide precursors, such as ribose-5-phosphate) and redox homeostasis and ultimately facilitates cancer cell survival and growth. NRF2 or CARM1 knockdown results in decreased H3R17me2a accompanied by the reduction of glucose-6-phosphate dehydrogenase under low glucose conditions. Collectively, this study reveals a significant role of CARM1 in regulating the tumor metabolic switch and identifies CARM1 as a potential therapeutic target for gastric cancer treatment.

NCAPH, ubiquitinated by TRIM21, promotes cell proliferation by inhibiting autophagy of cervical cancer through AKT/mTOR dependent signaling

Autophagy is closely related to the occurrence and development of human malignancies; however, the detailed mechanisms underlying autophagy in cervical cancer require further investigation. Previously, we found that the ectopic expression of NCAPH, a regulatory subunit of condensed protein complexes, significantly enhanced the proliferation of tumor cells; however, the underlying mechanisms were unclear. Here, we revealed that NCAPH is a novel autophagy-associated protein in cervical cancer that promotes cell proliferation by inhibiting autophagosome formation and reducing autophagy, with no effect on the cell cycle, apoptosis, or aging. Tripartite motif-containing protein 21 (TRIM21) is well known to be involved in inflammation, autoimmunity and cancer, mainly via its E3 ubiquitin ligase activity. Mass spectrometry and immunoprecipitation assays showed that TRIM21 interacted with NCAPH and decreased the protein stability of NCAPH via ubiquitination at the K11 lysine residue. Structural domain mutation analysis revealed that TRIM21 combined with NCAPH through its PRY/SPRY and CC domains and accelerated the degradation of NCAPH through the RING domain. Furthermore, TRIM21 promoted autophagosome formation and reduced cell proliferation by inhibiting NCAPH expression and the downstream AKT/mTOR pathway in cervical cancer cells. Immunohistochemical staining revealed that the protein expression of TRIM21 was negatively correlated with that of NCAPH and positively correlated with that of beclin-1 in cervical cancer tissues. Therefore, we provide evidence for the role of the TRIM21-NCAPH axis in cervical cancer autophagy and proliferation and the involvement of the AKT/mTOR signaling pathway in this process. These results deepen our understanding of the carcinogenesis of cervical cancer, broaden the understanding of the molecular mechanisms of TRIM21 and NCAPH, and provide guidance for individualized treatment of cervical cancer in the future.

AKT1 Promotes Tumorigenesis and Metastasis by Directly Phosphorylating Hexokinases

The importance of protein kinase B (AKT) in tumorigenesis and development is well established, but its potential regulation of metabolic reprogramming via phosphorylation of the hexokinase (HK) isozymes remains unclear. There are two HK family members (HK1/2) and three AKT family members (AKT1/2/3), with varied distribution of AKTs exhibiting distinct functions in different tissues and cell types. Although AKT is known to phosphorylate HK2 at threonine 473, AKT-mediated phosphorylation of HK1 has not been reported. We examined direct binding and phosphorylation of HK1/2 by AKT1 and identified the phosphorylation modification sites using coimmunoprecipitation, glutathione pull-down, western blotting, and in vitro kinase assays. Regulation of HK activity through phosphorylation by AKT1 was also examined. Uptake of 2-[1,2-3H]-deoxyglucose and production of lactate were investigated to determine whether AKT1 regulates glucose metabolism by phosphorylating HK1/2. Functional assays, immunohistochemistry, and tumor experiments in mice were performed to investigate whether AKT1-mediated regulation of tumor development is dependent on its kinase activity and/or the involvement of HK1/2. AKT interacted with and phosphorylated HK1 and HK2. Serine phosphorylation significantly increased AKT kinase activity, thereby enhancing glycolysis. Mechanistically, the phosphorylation of HK1 at serine 178 (S178) by AKT significantly decreased the Km and enhanced the Vmax by interfering with the formation of HK1 dimers. Mutations in the AKT phosphorylation sites of HK1 or HK2 significantly abrogated the stimulatory characteristics of AKT on glycolysis, tumorigenesis, and cell migration, invasion, proliferation, and metastasis. HK1-S178 phosphorylation levels were significantly correlated with the occurrence and metastasis of different types of clinical tumors. We conclude that AKT not only regulates tumor glucose metabolism by directly phosphorylating HK1 and HK2, but also plays important roles in tumor progression, proliferation, and migration.

Delineation of the role of G6PD in Alzheimer's disease and potential enhancement through microfluidic and nanoparticle approaches

Alzheimer's disease (AD) is a neurodegenerative pathologic entity characterized by the abnormal presence of tau and macromolecular Aβ deposition that leads to the degeneration or death of neurons. In addition to that, glucose-6-phosphate dehydrogenase (G6PD) has a multifaceted role in the process of AD development, where it can be used as both a marker and a target. G6PD activity is dysregulated due to its contribution to oxidative stress, neuroinflammation, and neuronal death. In this context, the current review presents a vivid depiction of recent findings on the relationship between AD progression and changes in the expression or activity of G6PD. The efficacy of the proposed G6PD-based therapeutics has been demonstrated in multiple studies using AD mouse models as representative animal model systems for cognitive decline and neurodegeneration associated with this disease. Innovative therapeutic insights are made for the boosting of G6PD activity via novel innovative nanotechnology and microfluidics tools in drug administration technology. Such approaches provide innovative methods of surpassing the blood-brain barrier, targeting step-by-step specific neural pathways, and overcoming biochemical disturbances that accompany AD. Using different nanoparticles loaded with G6DP to target specific organs, e.g., G6DP-loaded liposomes, enhances BBB penetration and brain distribution of G6DP. Many nanoparticles, which are used for different purposes, are briefly discussed in the paper. Such methods to mimic BBB on organs on-chip offer precise disease modeling and drug testing using microfluidic chips, requiring lower sample amounts and producing faster findings compared to conventional techniques. There are other contributions to microfluid in AD that are discussed briefly. However, there are some limitations accompanying microfluidics that need to be worked on to be used for AD. This study aims to bridge the gap in understanding AD with the synergistic use of promising technologies; microfluid and nanotechnology for future advancements.

Epigenetic modification of PHLDA2 is associated with tumor microenvironment and unfavorable outcome of immune checkpoint inhibitor-based therapies in clear cell renal cell carcinoma

BACKGROUND

A substantial proportion of patients with metastatic clear cell renal cell carcinoma (ccRCC) cannot derive benefit from immune checkpoint inhibitor (ICI) plus anti-angiogenic agent combination therapy, making identification of predictive biomarkers an urgent need. The members of pleckstrin homology-like domain family A (PHLDA) play critical roles in multiple cancers, whereas their roles in ccRCC remain unknown.

METHODS

Transcriptomic, clinical, genetic alteration and DNA methylation data were obtained for integrated analyses from TCGA database. RNA sequencing was performed on 117 primary tumors and 79 normal kidney tissues from our center. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis, gene set enrichment analysis were performed to explore transcriptomic features. Data from three randomized controlled trials (RCT), including CheckMate025, IMmotion151, JAVELIN101, were obtained for validation.

RESULTS

Members of PHLDA family were dysregulated in pan-cancer. Elevated PHLDA2 expression was associated with adverse clinicopathologic parameters and worse prognosis in ccRCC. Aberrant DNA hypomethylation contributed to up-regulation of PHLDA2. An immunosuppressive microenvironment featured by high infiltrates of Tregs and cancer-associated fibroblasts, was observed in ccRCC with higher PHLDA2 expression. Utilizing data from three RCTs, the association of elevated PHLDA2 expression with poor therapeutic efficacy of ICI plus anti-angiogenic combination therapy was confirmed.

CONCLUSIONS

Our study revealed that elevated PHLDA2 expression regulated by DNA hypomethylation was correlated with poor prognosis and immunosuppressive microenvironment, and highlighted the role of PHLDA2 as a robust biomarker for predicting therapeutic efficacy of ICI plus anti-angiogenic agent combination therapy in ccRCC, which expand the dimension of precision medicine.

TNKS1BP1 facilitates ubiquitination of CNOT4 by TRIM21 to promote hepatocellular carcinoma progression and immune evasion

Immune checkpoint inhibitors, particularly PD-1/PD-L1 blockades, have been approved for unresectable hepatocellular carcinoma (HCC). However, high resistance rates still limit their efficacy, highlighting the urgent need to understand the underlying mechanisms and develop strategies for overcoming the resistance. In this study, tankyrasel binding protein 1 (TNKS1BP1) was found to interact with tripartite motif containing 21 (TRIM21) and mediated the ubiquitination of CCR4-NOT transcription complex subunit 4 (CNOT4) at the K239 residue via K48 and K6 linkage, which was essential for its tumorigenesis function. Autophagy and lipid reprogramming were identified as two possible mechanisms underlying the pro-tumor effect of TNKS1BP1. Upregulated TNKS1BP1 inhibited autophagy while induced lipid accumulation by inhibiting the JAK2/STAT3 pathway upon the degradation of CNOT4 in HCC. Importantly, knocking down TNKS1BP1 synergized with anti-PD-L1 treatment by upregulating PD-L1 expression on tumor cells via the JAK2/STAT3 pathway, and remodeling the tumor microenvironment by increasing infiltration of tumor-infiltrating lymphocytes as well as augmenting the effect of cytotoxic T lymphocytes. In conclusion, this study identified TNKS1BP1 as a predictive biomarker for patient prognosis and a promising therapeutic target to overcome anti-PD-L1 resistance in HCC.

METTL3-m6A methylation inhibits the proliferation and viability of type II alveolar epithelial cells in acute lung injury by enhancing the stability and translation efficiency of Pten mRNA

BACKGROUND

The pathogenesis of acute lung injury (ALI) involves a severe inflammatory response, leading to significant morbidity and mortality. N6-methylation of adenosine (m6A), an abundant mRNA nucleotide modification, plays a crucial role in regulating mRNA metabolism and function. However, the precise impact of m6A modifications on the progression of ALI remains elusive.

METHODS

ALI models were induced by either intraperitoneal injection of lipopolysaccharide (LPS) into C57BL/6 mice or the LPS-treated alveolar type II epithelial cells (AECII) in vitro. The viability and proliferation of AECII were assessed using CCK-8 and EdU assays. The whole-body plethysmography was used to record the general respiratory functions. M6A RNA methylation level of AECII after LPS insults was detected, and then the "writer" of m6A modifications was screened. Afterwards, we successfully identified the targets that underwent m6A methylation mediated by METTL3, a methyltransferase-like enzyme. Last, we evaluated the regulatory role of METTL3-medited m6A methylation at phosphatase and tensin homolog (Pten) in ALI, by assessing the proliferation, viability and inflammation of AECII.

RESULTS

LPS induced marked damages in respiratory functions and cellular injuries of AECII. The m6A modification level in mRNA and the expression of METTL3, an m6A methyltransferase, exhibited a notable rise in both lung tissues of ALI mice and cultured AECII cells subjected to LPS treatment. METTL3 knockdown or inhibition improved the viability and proliferation of LPS-treated AECII, and also reduced the m6A modification level. In addition, the stability and translation of Pten mRNA were enhanced by METTL3-mediated m6A modification, and over-expression of PTEN reversed the protective effect of METTL3 knockdown in the LPS-treated AECII.

CONCLUSIONS

The progression of ALI can be attributed to the elevated levels of METTL3 in AECII, as it promotes the stability and translation of Pten mRNA through m6A modification. This suggests that targeting METTL3 could offer a novel approach for treating ALI.

TRIM21 is critical in regulating hepatocellular carcinoma growth and response to therapy by altering the MST1/YAP pathway

Liver cancer is the sixth most common cancer and the third leading cause of cancer-related death globally. Despite efforts being made in last two decades in cancer diagnosis and treatment, the 5-year survival rate of liver cancer remains extremely low. TRIM21 participates in cancer metabolism, glycolysis, immunity, chemosensitivity and metastasis by targeting various substrates for ubiquitination. TRIM21 serves as a prognosis marker for human hepatocellular carcinoma (HCC), but the mechanism by which TRIM21 regulates HCC tumorigenesis and progression remains elusive. In this study, we demonstrated that TRIM21 protein levels were elevated in human HCC. Elevated TRIM21 expression was associated with HCC progression and poor survival. Knockdown of TRIM21 in HCC cell lines significantly impaired cell growth and metastasis and enhanced sorafenib-induced toxicity. Mechanistically, we found that knockdown of TRIM21 resulted in cytosolic translocation and inactivation of YAP. At the molecular level, we further identified that TRIM21 interacted and induced ubiquitination of MST1, which resulted in MST1 degradation and YAP activation. Knockdown of MST1 or overexpression of YAP reversed TRIM21 knockdown-induced impairment of HCC growth and chemosensitivity. Taken together, the current study demonstrates a novel mechanism that regulates the Hippo pathway and reveals TRM21 as a critical factor that promotes growth and chemoresistance in human HCC.

Metabolic Roles of HIF1, c-Myc, and p53 in Glioma Cells

The metabolic reprogramming that promotes tumorigenesis in glioblastoma is induced by dynamic alterations in the hypoxic tumor microenvironment, as well as in transcriptional and signaling networks, which result in changes in global genetic expression. The signaling pathways PI3K/AKT/mTOR and RAS/RAF/MEK/ERK stimulate cell metabolism, either directly or indirectly, by modulating the transcriptional factors p53, HIF1, and c-Myc. The overexpression of HIF1 and c-Myc, master regulators of cellular metabolism, is a key contributor to the synthesis of bioenergetic molecules that mediate glioma cell transformation, proliferation, survival, migration, and invasion by modifying the transcription levels of key gene groups involved in metabolism. Meanwhile, the tumor-suppressing protein p53, which negatively regulates HIF1 and c-Myc, is often lost in glioblastoma. Alterations in this triad of transcriptional factors induce a metabolic shift in glioma cells that allows them to adapt and survive changes such as mutations, hypoxia, acidosis, the presence of reactive oxygen species, and nutrient deprivation, by modulating the activity and expression of signaling molecules, enzymes, metabolites, transporters, and regulators involved in glycolysis and glutamine metabolism, the pentose phosphate cycle, the tricarboxylic acid cycle, and oxidative phosphorylation, as well as the synthesis and degradation of fatty acids and nucleic acids. This review summarizes our current knowledge on the role of HIF1, c-Myc, and p53 in the genic regulatory network for metabolism in glioma cells, as well as potential therapeutic inhibitors of these factors.

Proteomic studies of VEGFR2 in human placentas reveal protein associations with preeclampsia, diabetes, gravidity, and labor

VEGFR2 (Vascular endothelial growth factor receptor 2) is a central regulator of placental angiogenesis. The study of the VEGFR2 proteome of chorionic villi at term revealed its partners MDMX (Double minute 4 protein) and PICALM (Phosphatidylinositol-binding clathrin assembly protein). Subsequently, the oxytocin receptor (OT-R) and vasopressin V1aR receptor were detected in MDMX and PICALM immunoprecipitations. Immunogold electron microscopy showed VEGFR2 on endothelial cell (EC) nuclei, mitochondria, and Hofbauer cells (HC), tissue-resident macrophages of the placenta. MDMX, PICALM, and V1aR were located on EC plasma membranes, nuclei, and HC nuclei. Unexpectedly, PICALM and OT-R were detected on EC projections into the fetal lumen and OT-R on 20-150 nm clusters therein, prompting the hypothesis that placental exosomes transport OT-R to the fetus and across the blood-brain barrier. Insights on gestational complications were gained by univariable and multivariable regression analyses associating preeclampsia with lower MDMX protein levels in membrane extracts of chorionic villi, and lower MDMX, PICALM, OT-R, and V1aR with spontaneous vaginal deliveries compared to cesarean deliveries before the onset of labor. We found select associations between higher MDMX, PICALM, OT-R protein levels and either gravidity, diabetes, BMI, maternal age, or neonatal weight, and correlations only between PICALM-OT-R (p < 2.7 × 10-8), PICALM-V1aR (p < 0.006), and OT-R-V1aR (p < 0.001). These results offer for exploration new partnerships in metabolic networks, tissue-resident immunity, and labor, notably for HC that predominantly express MDMX.

Systems genetics of influenza A virus-infected mice identifies TRIM21 as a critical regulator of pulmonary innate immune response

Tripartite motif 21 (TRIM21) is a cytosolic Fc receptor that targets antibody-bound, internalized pathogens for destruction. Apart from this intrinsic defense role, TRIM21 is implicated in autoimmune diseases, inflammation, and autophagy. Whether TRIM21 participates in host interactions with influenza A virus (IAV), however, is unknown. By computational modeling of body weight and lung transcriptome data from the BXD parents (C57BL/6 J (B6) and DBA/2 J (D2)) and 41 BXD mouse strains challenged by IAV, we reveal that a Trim21-associated gene network modulates the early host responses to IAV infection. Trim21 transcripts were significantly upregulated in infected mice of both B6 and D2 backgrounds. Its expression was significantly higher in infected D2 than in infected B6 early after infection and significantly correlated with body weight loss. We identified significant trans-eQTL on chromosome 14 that regulates Trim21 expression. Nr1d2 and Il3ra were among the strongest candidate genes. Pathway analysis found Trim21 to be involved in inflammation and immunity related pathways, such as inflammation signaling pathways (TNF, IL-17, and NF-κB), viral detection signaling pathways (NOD-like and RIG-I-like), influenza, and other respiratory viral infections. Knockdown of TRIM21 in human lung epithelial A549 cells significantly augmented IAV-induced expression of IFNB1, IFNL1, CCL5, CXCL10, and IFN-stimulated genes including DDX58 and IFIH1, among others. Our data suggest that a TRIM21-associated gene network is involved in several aspects of inflammation and viral detection mechanisms during IAV infection. We identify and validate TRIM21 as a critical regulator of innate immune responses to IAV in human lung epithelial cells.

Trim21 Regulates the Postnatal Development and Thermogenesis of Brown Adipose Tissue

Brown adipose tissue undergoes rapid postnatal development to mature and plays a crucial role in thermoregulation and energy expenditure, which protects against cold and obesity. Herein, it is shown that the expression of Trim21 mRNA level of interscapular brown adipose tissue elevates after birth, and peaks at P14 (postnatal day 14). Trim21 depletion severely impairs the maturation of interscapular brown adipose tissue, decreases the expression of a series of thermogenic genes, and reduces energy expenditure. Consistently, the loss of Trim21 also leads to a suppression of white adipose tissue "browning", in response to cold exposure and a β-adrenergic agonist, CL316,243. In addition, Trim21-/- mice are more prone to high-fat diet-induced obesity compared with the control littermates. Taken together, the study for the first time reveals a critical role of Trim21 in regulating iBAT postnatal development and thermogenesis.

HuaChanSu suppresses the growth of hepatocellular carcinoma cells by interfering with pentose phosphate pathway through down-regulation of G6PD enzyme activity and expression

HuaChanSu is active water extracts from the skin of Bufo bufo gargarizans Cantor. It has been already used to treat clinical cancers including HCC (Hepatocellular carcinoma, HCC), however, the molecular mechanisms under HuaChanSu's anti-cancer effects remain unclear. PPP (Pentose phosphate pathway, PPP), the major source of ribose and NADPH (Nicotinamide adenine dinucleotide phosphate, NADPH), is always over-activated and particularly critical for tumor cells growth. In this study, firstly, we illustrate that HuaChanSu restrains the growth of human hepatoma cells. More importantly, we demonstrate that the expression of G6PD (Glucose-6-phosphate dehydrogenase, G6PD), the first rate-limiting enzyme of the PPP, is restrained in human hepatoma cells after treatment with HuaChanSu. Additionally, our results show that G6PD enzyme activity and dimer formation are inhibited by HuaChanSu. Furthermore, we find that HuaChanSu could inhibit NADPH production and nucleotide level. In addition, we identify that expression of PLK1 (Polo-like kinase 1, PLK1) is also reduced in response to HuaChanSu, and knockdown of PLK1 restrains enzyme activity and dimer formation of G6PD, but has no effect on G6PD protein level. Subsequently, we demonstrate that inhibition of G6PD could restrain the proliferation of tumor cells and enhance the inhibitory effect of HuaChanSu on cell proliferation of human hepatoma cells. In conclusion, for the first time, our study reveals that HuaChanSu interferes with PPP via suppression of G6PD expression and enzyme activity to restrain growth of tumor cells, and these results provide a novel insight for the anti-hepatoma mechanisms of HuaChanSu and promote the innovation of the research model of TCM. Moreover, the development of drugs targeting abnormal tumor metabolism is currently a hot topic, our works provide theoretical support for further drug development from HuaChanSu, meanwhile, the revelation of the new molecular mechanism also provides a new perspective for the study of the pathogenesis of liver cancer.

Short abstract

HuaChanSu suppresses expression of G6PD, the first rate-limiting enzyme of the PPP, restrains G6PD enzyme activity and dimer formation via inhibition of PLK1, knockdown of G6PD could impair the growth of human hepatoma cells and increase the blocking effect of HuaChanSu on cell proliferation of cancer cells. In addition, HuaChanSu restrains NADPH production and nucleotide level, implying the suppression of PPP flux. Our study suggests that HuaChanSu interferes with PPP via G6PD inhibition to exert anti-hepatoma effects.

FGF19 promotes nasopharyngeal carcinoma progression by inducing angiogenesis via inhibiting TRIM21-mediated ANXA2 ubiquitination

PURPOSE

Nasopharyngeal carcinoma (NPC) has characteristics of high invasion and early metastasis. Most NPC patients present with locoregionally advanced illness when first diagnosed. Therefore, it is urgent to discover NPC biomarkers. Fibroblast growth Factor 19 (FGF19) plays a role in various physiological or pathological processes, including cancer. In this research, we discovered the importance of FGF19 in NPC, and clarified its role in tumour angiogenesis.

METHODS

Western blotting, immunohistochemistry and ELISA were used to investigate FGF19 expression in NPC. Then we took CCK8, colony formation, Transwell and wound healing assays to identify the influence of FGF19 on NPC malignant behaviours. The proliferative and metastatic capacity of FGF19 were evaluated in nude mice and zebrafish. The role of FGF19 in angiogenesis was investigated by tube formation and Matrigel plug angiogenesis assays. We then evaluated the variation in Annexin A2(ANXA2) levels with the treatment of FGF19. Lastly, co-immunoprecipitation and ubiquitination assays were performed to identify the mechanisms involved.

RESULTS

FGF19 levels were elevated in tissues and serum of NPC patients and were associated with poor clinical stages. High expression of FGF19 promoted NPC malignant behaviours. In particular, FGF19 expression was correlated with microvessel density in tissues and NPC-derived FGF19 could accelerate angiogenesis in vitro and in vivo. Mechanistically, FGF19 influenced ANXA2 expression to promote angiogenesis. Moreover, tripartite motif-containing 21(TRIM21) interacted with ANXA2 and was responsible for ANXA2 ubiquitination.

CONCLUSION

FGF19 promoted NPC angiogenesis by inhibiting TRIM21-mediated ANXA2 ubiquitination. It may serve as a noninvasive biomarker for NPC and provides new insights for therapy.

G6PD and machine learning algorithms as prognostic and diagnostic indicators of liver hepatocellular carcinoma

BACKGROUND

Liver Hepatocellular carcinoma (LIHC) exhibits a high incidence of liver cancer with escalating mortality rates over time. Despite this, the underlying pathogenic mechanism of LIHC remains poorly understood.

MATERIALS & METHODS

To address this gap, we conducted a comprehensive investigation into the role of G6PD in LIHC using a combination of bioinformatics analysis with database data and rigorous cell experiments. LIHC samples were obtained from TCGA, ICGC and GEO databases, and the differences in G6PD expression in different tissues were investigated by differential expression analysis, followed by the establishment of Nomogram to determine the percentage of G6PD in causing LIHC by examining the relationship between G6PD and clinical features, and the subsequent validation of the effect of G6PD on the activity, migration, and invasive ability of hepatocellular carcinoma cells by using the low expression of LI-7 and SNU-449. Additionally, we employed machine learning to validate and compare the predictive capacity of four algorithms for LIHC patient prognosis.

RESULTS

Our findings revealed significantly elevated G6PD expression levels in liver cancer tissues as compared to normal tissues. Meanwhile, Nomogram and Adaboost, Catboost, and Gbdt Regression analyses showed that G6PD accounted for 46%, 31%, and 49% of the multiple factors leading to LIHC. Furthermore, we observed that G6PD knockdown in hepatocellular carcinoma cells led to reduced proliferation, migration, and invasion abilities. Remarkably, the Decision Tree C5.0 decision tree algorithm demonstrated superior discriminatory performance among the machine learning methods assessed.

CONCLUSION

The potential diagnostic utility of G6PD and Decision Tree C5.0 for LIHC opens up a novel avenue for early detection and improved treatment strategies for hepatocellular carcinoma.

The mTORC2 signaling network: targets and cross-talks

The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.

Diallyl disulfide induces DNA damage and growth inhibition in colorectal cancer cells by promoting POU2F1 ubiquitination

Previous studies have demonstrated that diallyl disulfide (DADS) exhibits potent anti-tumor activity. However, the pharmacological actions of DADS in inhibiting the growth of colorectal cancer (CRC) cells have not been clarified. Herein, we show that DADS treatment impairs the activation of the pentose phosphate pathway (PPP) to decrease PRPP (5-phosphate ribose-1-pyrophosphate) production, enhancing DNA damage and cell apoptosis, and inhibiting the growth of CRC cells. Mechanistically, DADS treatment promoted POU2F1 K48-linked ubiquitination and degradation by attenuating the PI3K/AKT signaling to up-regulate TRIM21 expression in CRC cells. Evidently, TRIM21 interacted with POU2F1, and induced the K272 ubiquitination of POU2F1. The effects of DADS on the enhanced K272 ubiquitination of POU2F1, the PPP flux, PRPP production, DNA damage and cell apoptosis as well as the growth of CRC tumors in vivo were significantly mitigated by TRIM21 silencing or activating the PI3K signaling in CRC cells. Conversely, the effects of DADS were enhanced by TRIM21 over-expression or inhibiting the PI3K/AKT signaling in CRC cells. Collectively, our findings reveal a novel mechanism by which DADS suppresses the growth of CRC by promoting POU2F1 ubiquitination, and may aid in design of novel therapeutic intervention of CRC.

Curcuminoids as Cell Signaling Pathway Modulators: A Potential Strategy for Cancer Prevention

Despite substantial advancements in curative modern medicine in the last few decades, cancer risk and casualty rates have continued to mount globally. The exact reason for cancer's onset and progression is still unknown. However, skeletal and functional abnormalities in the genetic code are assumed to be the primary cause of cancer. Many lines of evidence reported that some medicinal plants can be utilized to curb cancer cell proliferation with a safe, fruitful, and cost-efficient perspective. Curcuminoid, isolated from Curcuma longa, have gotten a lot of focus due to their anticancer potential as they reduce tumor progression, invasion, and dissemination. Further, they modulated signal transduction routes like MAPK, PI3K/Akt/mTOR, JAK/STAT, and Wnt/β-catenin, etc., and triggered apoptosis as well as actuated autophagy in malignant cells without altering the normal cells, thus preventing cancer progression. Besides, Curcuminoid also regulate the function and expression of anti-tumor and carcinogenic miRNAs. Clinical studies also reported the therapeutic effect of Curcuminoid against various cancer through decreasing specific biomarkers like TNF-α, Bcl-2, COX-2, PGE2, VEGF, IκKβ, and various cytokines like IL-12p70, IL-10, IL-2, IFN-γ levels and increasing in p53 and Bax levels. Thus, in the present review, we abridged the modulation of several signal transduction routes by Curcuminoids in various malignancies, and its modulatory role in the initiation of tumor-suppressive miRNAs and suppression of the oncogenic miRNAs are explored. Additionally, various pharmacokinetic approaches have been projected to address the Curcuminoids bioavailability like the use of piperine as an adjuvant; nanotechnology- based Curcuminoids preparations utilizing Curcuminoids analogues are also discussed.

A feedback loop of PPP and PI3K/AKT signal pathway drives regorafenib-resistance in HCC

BACKGROUND

Hepatocellular carcinoma (HCC) is a principal type of liver cancer with high incidence and mortality rates. Regorafenib is a novel oral multikinase inhibitor for second-line therapy for advanced HCC. However, resistance to regorafenib is gradually becoming a dilemma for HCC and the mechanism remains unclear. In this study, we aimed to reveal the metabolic profiles of regorafenib-resistant cells and the key role and mechanism of the most relevant metabolic pathway in regorafenib resistance.

METHODS

Metabolomics was performed to detect the metabolic alteration between drug-sensitive and regorafenib-resistant cells. Colony formation assay, CCK-8 assay and flow cytometry were applied to observe cell colony formation, cell proliferation and apoptosis, respectively. The protein and mRNA levels were detected by western blot and RT-qPCR. Cell lines of Glucose-6-phosphate dehydrogenase(G6PD) knockdown in regorafenib-resistant cells or G6PD overexpression in HCC cell lines were stably established by lentivirus infection technique. G6PD activity, NADPH level, NADPH/NADP+ ratio, the ratio of ROS positive cells, GSH level, and GSH/GSSG ratio were detected to evaluate the anti-oxidative stress ability of cells. Phosphorylation levels of NADK were evaluated by immunoprecipitation.

RESULTS

Metabonomics analysis revealed that pentose phosphate pathway (PPP) was the most relevant metabolic pathway in regorafenib resistance in HCC. Compared with drug-sensitive cells, G6PD enzyme activity, NADPH level and NADPH/NADP+ ratio were increased in regorafenib-resistant cells, but the ratio of ROS positive cells and the apoptosis rate under the conditions of oxidative stress were decreased. Furthermore, G6PD suppression using shRNA or an inhibitor, sensitized regorafenib-resistant cells to regorafenib. In contrast, G6PD overexpression blunted the effects of regorafenib to drug-sensitive cells. Mechanistically, G6PD, the rate-limiting enzyme of PPP, regulated the PI3K/AKT activation. Furthermore, PI3K/AKT inhibition decreased G6PD protein expression, G6PD enzymatic activity and the capacity of PPP to anti-oxidative stress possibly by inhibited the expression and phosphorylation of NADK.

CONCLUSION

Taken together, a feedback loop of PPP and PI3K/AKT signal pathway drives regorafenib-resistance in HCC and targeting the feedback loop could be a promising approach to overcome drug resistance.

The TRIM21-FOXD1-BCL-2 axis underlies hyperglycaemic cell death and diabetic tissue damage

Chronic hyperglycaemia is a devastating factor that causes diabetes-induced damage to the retina and kidney. However, the precise mechanism by which hyperglycaemia drives apoptotic cell death is incompletely known. Herein, we found that FOXD1, a FOX family transcription factor specifically expressed in the retina and kidney, regulated the transcription of BCL-2, a master regulator of cell survival. Intriguingly, the protein level of FOXD1, which responded negatively to hyperglycaemic conditions, was controlled by the TRIM21-mediated K48-linked polyubiquitination and subsequent proteasomal degradation. The TRIM21-FOXD1-BCL-2 signalling axis was notably active during diabetes-induced damage to murine retinal and renal tissues. Furthermore, we found that tartary buckwheat flavonoids effectively reversed the downregulation of FOXD1 protein expression and thus restored BCL-2 expression and facilitated the survival of retinal and renal tissues. In summary, we identified a transcription factor responsible for BCL-2 expression, a signalling axis (TRM21-FOXD1-BCL-2) underlying hyperglycaemia-triggered apoptosis, and a potential treatment for deleterious diabetic complications.

The Emerging Roles of the Metabolic Regulator G6PD in Human Cancers

Metabolic reprogramming, especially reprogrammed glucose metabolism, is a well-known cancer hallmark related to various characteristics of tumor cells, including proliferation, survival, metastasis, and drug resistance. Glucose-6-phosphate dehydrogenase (G6PD) is the first and rate-limiting enzyme of the pentose phosphate pathway (PPP), a branch of glycolysis, that converts glucose-6-phosphate (G6P) into 6-phosphogluconolactone (6PGL). Furthermore, PPP produces ribose-5-phosphate (R5P), which provides sugar-phosphate backbones for nucleotide synthesis as well as nicotinamide adenine dinucleotide phosphate (NADPH), an important cellular reductant. Several studies have shown enhanced G6PD expression and PPP flux in various tumor cells, as well as their correlation with tumor progression through cancer hallmark regulation, especially reprogramming cellular metabolism, sustaining proliferative signaling, resisting cell death, and activating invasion and metastasis. Inhibiting G6PD could suppress tumor cell proliferation, promote cell death, reverse chemoresistance, and inhibit metastasis, suggesting the potential of G6PD as a target for anti-tumor therapeutic strategies. Indeed, while challenges-including side effects-still remain, small-molecule G6PD inhibitors showing potential anti-tumor effect either when used alone or in combination with other anti-tumor drugs have been developed. This review provides an overview of the structural significance of G6PD, its role in and regulation of tumor development and progression, and the strategies explored in relation to G6PD-targeted therapy.

Placenta-derived exosomal miR-135a-5p promotes gestational diabetes mellitus pathogenesis by activating PI3K/AKT signalling pathway via SIRT1

Most people are aware of gestational diabetes mellitus (GDM), a dangerous pregnancy complication in which pregnant women who have never been diagnosed with diabetes develop chronic hyperglycaemia. Exosomal microRNA (miRNA) dysregulation has been shown to be a key player in the pathophysiology of GDM. In this study, we looked into how placental exosomes and their miRNAs may contribute to GDM. When compared to exosomes from healthy pregnant women, it was discovered that miR-135a-5p was elevated in placenta-derived exosomes that were isolated from the maternal peripheral plasma of GDM women. Additionally, we discovered that miR-135a-5p encouraged HTR-8/SVneo cell growth, invasion and migration. Further research revealed that miR-135a-5p activates HTR-8/SVneo cells' proliferation, invasion and migration by promoting PI3K/AKT pathway activity via Sirtuin 1 (SIRT1). The transfer of exosomal miR-135a-5p generated from the placenta could be viewed as a promising agent for targeting genes and pertinent pathways involved in GDM, according to our findings.

Pan-PI3K inhibition with copanlisib overcomes Treg- and M2-TAM-mediated immune suppression and promotes anti-tumor immune responses

The PI3K pathway is one of the most frequently altered signaling pathways in human cancer. In addition to its function in cancer cells, PI3K plays a complex role in modulating anti-tumor immune responses upon immune checkpoint inhibition (ICI). Here, we evaluated the effects of the pan-Class I PI3K inhibitor copanlisib on different immune cell types in vitro and on tumor growth and immune cell infiltration in syngeneic murine cancer models. Intermittent treatment with copanlisib resulted in a strong in vivo anti-tumor efficacy, increased tumor infiltration of activated T cells and macrophages, and increased CD8+ T cell/regulatory T cell and M1/M2 macrophage ratios. The strong in vivo efficacy was at least partially due to immunomodulatory activity of copanlisib, as in vitro these murine cancer cells were resistant to PI3K inhibition. Furthermore, the combination of copanlisib with the ICI antibody anti-PD-1 demonstrated enhanced anti-tumor efficacy in both ICI-sensitive and insensitive syngeneic mouse tumor models. Importantly, in an ICI-sensitive model, combination therapy resulted in complete remission and prevention of tumor recurrence. Thus, the combination of ICIs with PI3K inhibition by intermittently dosed copanlisib represents a promising new strategy to increase sensitivity to ICI therapies and to treat human solid cancers.

The interconnected roles of TRIM21/Ro52 in systemic lupus erythematosus, primary Sjögren's syndrome, cancers, and cancer metabolism

Protein tripartite motif-containing 21 (TRIM21/Ro52), an E3 ubiquitin ligase, is an essential regulator of innate immunity, and its dysregulation is closely associated with the development of autoimmune diseases, predominantly systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). TRIM21 /Ro52 also features anti-cancer and carcinogenic functions according to different malignancies. The interconnected role of TRIM21/Ro52 in regulating autoimmunity and cell metabolism in autoimmune diseases and malignancies is implicated. In this review, we summarize current findings on how TRIM21/Ro52 affects inflammation and tumorigenesis, and investigate the relationship between TRIM21/Ro52 expression and the formation of lymphoma and breast cancer in SLE and pSS populations.

Inflammation-induced TRIM21 represses hepatic steatosis by promoting the ubiquitination of lipogenic regulators

Nonalcoholic steatohepatitis (NASH) is a leading cause for chronic liver diseases. Current therapeutic options are limited due to an incomplete mechanistic understanding of how steatosis transitions to NASH. Here we show that the TRIM21 E3 ubiquitin ligase is induced by the synergistic actions of proinflammatory TNF-α and fatty acids in livers of humans and mice with NASH. TRIM21 ubiquitinates and degrades ChREBP, SREBP1, ACC1, and FASN, key regulators of de novo lipogenesis, and A1CF, an alternative splicing regulator of the high-activity ketohexokinase-C (KHK-C) isoform and rate-limiting enzyme of fructose metabolism. TRIM21-mediated degradation of these lipogenic activators improved steatosis and hyperglycemia as well as fructose and glucose tolerance. Our study identifies TRIM21 as a negative regulator of liver steatosis in NASH and provides mechanistic insights into an immunometabolic crosstalk that limits fatty acid synthesis and fructose metabolism during metabolic stress. Thus, enhancing this natural counteracting force of steatosis through inhibition of key lipogenic activators via TRIM21-mediated ubiquitination may provide a therapeutic opportunity to treat NASH.

Metabolomics reveals that PS-NPs promote lung injury by regulating prostaglandin B1 through the cGAS-STING pathway

Nanoplastics have been widely studied as environmental pollutants, which can accumulate in the human body through the food chain or direct contact. Research has shown that nanoplastics can affect the immune system and mitochondrial function, but the underlying mechanisms are unclear. Lungs and macrophages have important immune and metabolic functions. This study explored the effects of 100 nm PS-NPs on innate immunity, mitochondrial function, and cellular metabolism-related pathways in lung (BEAS-2B) cells and macrophages (RAW264.7). The results had shown that PS-NPs exposure caused a decrease in mitochondrial membrane potential, intracellular ROS accumulation, and Ca2+ overload, and activated the cGAS-STING signaling pathway related to innate immunity. These changes had been observed at concentrations of PS-NPs as low as 60 μg/mL, which might have been comparable to environmental levels. Non-target metabolomics and Western Blotting results confirmed that PS-NPs regulated prostaglandin B1 and other metabolites to cause cell damage through the cGAS-STING pathway. Supplementation of prostaglandin B1 alleviated the immune activation and metabolic disturbance caused by PS-NPs exposure. This study identified PS-NPs-induced innate immune activation, mitochondrial dysfunction, and metabolic toxicity pathways, providing new insights into the potential for adverse outcomes of NPs in human life.

Molecular Mechanisms Underpinning Immunometabolic Reprogramming: How the Wind Changes during Cancer Progression

Metabolism and the immunological state are intimately intertwined, as defense responses are bioenergetically expensive. Metabolic homeostasis is a key requirement for the proper function of immune cell subsets, and the perturbation of the immune-metabolic balance is a recurrent event in many human diseases, including cancer, due to nutrient fluctuation, hypoxia and additional metabolic changes occurring in the tumor microenvironment (TME). Although much remains to be understood in the field of immunometabolism, here, we report the current knowledge on both physiological and cancer-associated metabolic profiles of immune cells, and the main molecular circuits involved in their regulation, highlighting similarities and differences, and emphasizing immune metabolic liabilities that could be exploited in cancer therapy to overcome immune resistance.

PI3K/mTOR inhibitors promote G6PD autophagic degradation and exacerbate oxidative stress damage to radiosensitize small cell lung cancer

Our previous study revealed that PI3K/AKT/mTOR signaling was associated with SCLC radioresistance. SBC2 cells were used as primary radioresistance models, while H446 cells were continuously exposed to ionizing radiation (IR) to develop acquired radioresistance. Cell viability and apoptosis assays were used to investigate synergistic effects of BEZ235/GSK2126458 and IR in vitro, while immunoblotting, metabolite quantitative analysis and bioinformatic analyses were utilized to explore the underlying mechanism. Both genetically engineered mouse models (GEMM) and subcutaneous tumor models were used to confirm the synergistic effect in vivo. Key molecules of PI3K/AKT/mTOR signaling were upregulated after IR, which was correlated with primary radioresistance, and they were more expressed in acquired radioresistant cells. BEZ235/GSK2126458 effectively enhanced the cytotoxic effects of IR. BEZ235/GSK2126458 plus IR elevated γ-H2AX and p-Nrf2 expression, suggesting DNA and oxidative stress damage were intensified. Mechanistically, BEZ235/GSK2126458 plus IR significantly reduced the expression of G6PD protein, the rate-limiting enzyme of the pentose phosphate pathway (PPP). In detail, PI3K/mTOR inhibitors reinforced interaction between G6PD and HSPA8/HSC70, and G6PD was degraded by chaperone-mediated autophagy processes. Their metabolites (NADPH and R-5P) were decreased, and ROS levels were indirectly elevated, both of which exacerbated cell death. PI3K/AKT/mTOR signaling activator, insulin, enhanced SCLC radioresistance, while the synergistic effect of BEZ235/GSK2126458 and IR can be attenuated by N-acetylcysteine, and enhanced by 6-amino niacinamide. GEMM and allograft transplantation assays further confirmed their synergistic effect in vivo. This study provided insights into the connection between PI3K/AKT/mTOR signaling and the PPP underlying radioresistance and provided evidence of mechanisms supporting PI3K/mTOR inhibitors as possible therapeutic strategies to abrogate SCLC radioresistance.

TRIM21-Promoted FSP1 Plasma Membrane Translocation Confers Ferroptosis Resistance in Human Cancers

Ferroptosis, an iron-dependent form of regulated cell death driven by excessive accumulation of lipid peroxides, has become a promising strategy in cancer treatment. Cancer cells exploit antioxidant proteins, including Ferroptosis Suppressor Protein 1 (FSP1), to prevent ferroptosis. In this study, it is found that the E3 ubiquitin ligase TRIM21 bound to FSP1 and mediated its ubiquitination on K322 and K366 residues via K63 linkage, which is essential for its membrane translocation and ferroptosis suppression ability. It is further verified the protective role of the TRIM21-FSP1 axis in RSL3-induced ferroptosis in cancer cells and a subcutaneous tumor model. Moreover, TRIM21 is highly expressed in multiple gastrointestinal (GI) tumors, and its expression is further stimulated upon ferroptosis induction in cancer cells and the KPC mouse model. In summary, This study identifies TRIM21 as a negative regulator of ferroptosis through K63 ubiquitination of FSP1, which can serve as a therapeutic target to enhance the chemosensitivity of tumors based on ferroptosis induction.