PGK1 represses autophagy-mediated cell death to promote the proliferation of liver cancer cells by phosphorylating PRAS40

Leonurine improves atherosclerosis by activating foam cell autophagy and metabolic remodeling via METTL3-mediated AKT1S1 mRNA stability modulation

BACKGROUND

Atherosclerosis (AS) is the most prevalent cardiovascular disease and remains the major contributor to death and mortality globally. Leonurine (LEO) is a unique alkaloid compound with protective effects on the cardiovascular system. However, the exact mechanisms underlying its cardiovascular-protecting action are still not fully elucidated. The methyltransferase 3 (METTL3), the catalytic core of the N6-methyladenosine modification (m6A) methyltransferase complex, has been shown to inhibit autophagy and exacerbate the process of AS via regulation of m6A modification of mRNA.

PURPOSE

We aimed to determine whether the inhibited effect of LEO on AS is related to METTL3-mediated AKT1S1 stability.

METHODS

The apolipoprotein E (ApoE) knockout mice was subjected to a high-fat diet (HFD), and THP-1 derived macrophages was exposed to oxidized low-density lipoprotein (ox-LDL), to establish the animal and cellular models of AS, respectively.

RESULTS

We found that LEO effectively improved AS and reduced the plaque area and inflammation via diminishing macrophage lipid accumulation and remodeling the lipid metabolism profile. LEO activated ox-LDL-induced macrophage autophagy, enhancing lipid metabolism decrease, according to the lipidomic and molecular biology analyses. Additionally, LEO caused a marked increase in autophagy marker levels in mouse models with advanced AS. Furthermore, we found that LEO reactivated autophagy and reversed lipid accumulation by suppressing METTL3 expression. The m6A-seq from ox-LDL-induced macrophages showed that a total of five autophagy-related mRNA transcripts (AKT1S1, AKT1, RB1CC1, CFLAR, and MTMR4) were altered, and AKT1S1 was significantly upregulated by LEO. Mechanistically, LEO-mediated regulation of METTL3 decreased AKT1S1 expression by attenuating its mRNA stability. Silencing AKT1S1 inhibited LEO-METTL3 axis-mediated autophagy and enhanced lipid accumulation in ox-LDL-induced macrophages.

CONCLUSION

The study first revealed that LEO exerts anti-atherosclerotic effect by activating METTL3-mediated macrophage autophagy in vivo and in vitro. The mechanism of LEO was further found to be the enhancement of METTL3-mediated AKT1S1 stability to activate autophagy thereby reducing lipid accumulation. This study provides a new perspective of natural medicines on the treatment of AS via an epigenetic manner.

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.

Novel energy optimizer, meldonium, rapidly restores acute hypobaric hypoxia-induced brain injury by targeting phosphoglycerate kinase 1

BACKGROUND

Acute hypobaric hypoxia-induced brain injury has been a challenge in the health management of mountaineers; therefore, new neuroprotective agents are urgently required. Meldonium, a well-known cardioprotective drug, has been reported to have neuroprotective effects. However, the relevant mechanisms have not been elucidated. We hypothesized that meldonium may play a potentially novel role in hypobaric hypoxia cerebral injury.

METHODS

We initially evaluated the neuroprotection efficacy of meldonium against acute hypoxia in mice and primary hippocampal neurons. The potential molecular targets of meldonium were screened using drug-target binding Huprot™ microarray chip and mass spectrometry analyses after which they were validated with surface plasmon resonance (SPR), molecular docking, and pull-down assay. The functional effects of such binding were explored through gene knockdown and overexpression.

RESULTS

The study clearly shows that pretreatment with meldonium rapidly attenuates neuronal pathological damage, cerebral blood flow changes, and mitochondrial damage and its cascade response to oxidative stress injury, thereby improving survival rates in mice brain and primary hippocampal neurons, revealing the remarkable pharmacological efficacy of meldonium in acute high-altitude brain injury. On the one hand, we confirmed that meldonium directly interacts with phosphoglycerate kinase 1 (PGK1) to promote its activity, which improved glycolysis and pyruvate metabolism to promote ATP production. On the other hand, meldonium also ameliorates mitochondrial damage by PGK1 translocating to mitochondria under acute hypoxia to regulate the activity of TNF receptor-associated protein 1 (TRAP1) molecular chaperones.

CONCLUSION

These results further explain the mechanism of meldonium as an energy optimizer and provide a strategy for preventing acute hypobaric hypoxia brain injury at high altitudes.

Analysis of the Anticancer Mechanism of OR3 Pigment from Streptomyces coelicolor JUACT03 Against the Human Hepatoma Cell Line Using a Proteomic Approach

This study assessed OR3 pigment, derived from Streptomyces coelicolor JUACT03, for its anticancer potential on HepG2 liver cancer cells and its safety on HEK293 normal cells. OR3 induced apoptosis and inhibited HepG2 cell proliferation, confirmed by caspase activation, Sub-G1 phase cell cycle arrest, and reduced colony formation. Proteomic analysis revealed altered expression of proteins associated with ribosomal function, mRNA processing, nuclear transport, proteasome activity, carbohydrate metabolism, chaperone function, histone regulation, and vesicle-mediated transport. Downregulation of proteins in MAPKAP kinase1, EIF2, mTOR, and EIF4 pathways contributed to apoptosis and cell cycle arrest. Changes in c-MYC, FUBP1 target proteins and upregulation of Prohibitin-1 (PHB1) were also noted. Western blot analysis supported alterations in eIF2, mTOR, and RAN pathways, including downregulation of RAB 5, c-MYC, p38, MAPK1, and MAPK3. OR3 exhibited significant anti-angiogenic activity in the in ovo CAM assay. In summary, OR3 demonstrated strong anticancer effects, inducing apoptosis, hindering proliferation, and displaying antiangiogenic properties. These findings highlight OR3's potential as an anticancer drug candidate, warranting further in vivo exploration.

Hypoxia-associated autophagy flux dysregulation in human cancers

A general feature of cancer is hypoxia, determined as low oxygen levels. Low oxygen levels may cause cells to alter in ways that contribute to tumor growth and resistance to treatment. Hypoxia leads to variations in cancer cell metabolism, angiogenesis and metastasis. Furthermore, a hypoxic tumor microenvironment might induce immunosuppression. Moreover, hypoxia has the potential to impact cellular processes, such as autophagy. Autophagy refers to the catabolic process by which damaged organelles and toxic macromolecules are broken down. The abnormal activation of autophagy has been extensively recorded in human tumors and it serves as a regulator of cell growth, spread to other parts of the body, and resistance to treatment. There is a correlation between hypoxia and autophagy in human malignancies. Hypoxia can regulate the activity of AMPK, mTOR, Beclin-1, and ATGs to govern autophagy in human malignancies. Furthermore, HIF-1α, serving as an indicator of low oxygen levels, controls the process of autophagy. Hypoxia-induced autophagy has a crucial role in regulating the growth, spread, and resistance to treatment in human malignancies. Hypoxia-induced regulation of autophagy can impact other mechanisms of cell death, such as apoptosis. Chemoresistance and radioresistance have become significant challenges in recent years. Hypoxia-mediated autophagy plays a crucial role in determining the response to these therapeutic treatments.

PGK1 is a potential biomarker for early diagnosis and prognosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a common type of liver cancer, is increasing in incidence worldwide. An early diagnosis of hepatocellular carcinoma (HCC) is still challenging: Currently, few biomarkers are available to diagnose the early stage of HCC, therefore, additional prognostic biomarkers are required to identify potential risk factors. The present study analyzed gene expression levels of HCC tissue samples and the protein expression levels obtained from the GSE46408 HCC dataset using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. The metabolically associated differentially expressed genes (DEGs), including DEGs involved in the glucose metabolism pathway, were selected for further analysis. Phosphoglycerate kinase 1 (PGK1), a glycolytic enzyme, was determined as a potential prognostic biomarker through Kaplan-Meier curve and clinical association variable analyses. This was also verified based on the expression levels of PGK1 in tumor tissue and protein expression levels in several liver cancer cell lines. PGK1 mRNA demonstrated a high level of expression in HCC tissue and was significantly associated with a poor prognosis, showing a negative association with survival time. In addition, as an independent risk factor, PGK1 may potentially be a valuable prognostic biomarker for patients with HCC. Furthermore, expression of PGK1 was associated with the early stages (stage I and T1) of HCC. Moreover, PGK1 mRNA expression levels demonstrated a positive association with progression of liver cancer. The results suggested that PGK1 mRNA may be involved in the degree of HCC malignancy and may be a future potential prognostic biomarker for HCC progression.

The oncogenic role and regulatory mechanism of PGK1 in human non-small cell lung cancer

BACKGROUND

Phosphoglycerate kinase 1 (PGK1) is a metabolic enzyme that participates in various biological and pathological processes. Dysregulated PGK1 has been observed in numerous malignancies. However, whether and how PGK1 affects non-small cell lung cancer (NSCLC) is not yet fully elucidated.

METHODS

Herein, the non-metabolic function of PGK1 in NSCLC was explored by integrating bioinformatics analyses, cellular experiments, and nude mouse xenograft models. The upstream regulators and downstream targets of PGK1 were examined using multiple techniques such as RNA sequencing, a dual-luciferase reporter assay, Co-immunoprecipitation, and Western blotting.

RESULTS

We confirmed that PGK1 was upregulated in NSCLC and this upregulation was associated with poor prognosis. Further in vitro and in vivo experiments demonstrated the promoting effects of PGK1 on NSCLC cell growth and metastasis. Additionally, we discovered that PGK1 interacted with and could be O-GlcNAcylated by OGT. The inhibition of PGK1 O-GlcNAcylation through OGT silencing or mutation at the T255 O-GlcNAcylation site could weaken PGK1-mediated NSCLC cell proliferation, colony formation, migration, and invasion. We also found that a low miR-24-3p level led to an increase in OGT expression. Additionally, PGK1 exerted its oncogenic properties by augmenting ERK phosphorylation and MCM4 expression.

CONCLUSIONS

PGK1 acted as a crucial mediator in controlling NSCLC progression. The miR-24-3p/OGT axis was responsible for PGK1 O-GlcNAcylation, and ERK/MCM4 were the downstream effectors of PGK1. It appears that PGK1 might be an attractive therapeutic target for the treatment of NSCLC.

NeuroD1-GPX4 signaling leads to ferroptosis resistance in hepatocellular carcinoma

Cell death resistance is a hallmark of tumor cells that drives tumorigenesis and drug resistance. Targeting cell death resistance-related genes to sensitize tumor cells and decrease their cell death threshold has attracted attention as a potential antitumor therapeutic strategy. However, the underlying mechanism is not fully understood. Recent studies have reported that NeuroD1, first discovered as a neurodifferentiation factor, is upregulated in various tumor cells and plays a crucial role in tumorigenesis. However, its involvement in tumor cell death resistance remains unknown. Here, we found that NeuroD1 was highly expressed in hepatocellular carcinoma (HCC) cells and was associated with tumor cell death resistance. We revealed that NeuroD1 enhanced HCC cell resistance to ferroptosis, a type of cell death caused by aberrant redox homeostasis that induces lipid peroxide accumulation, leading to increased HCC cell viability. NeuroD1 binds to the promoter of glutathione peroxidase 4 (GPX4), a key reductant that suppresses ferroptosis by reducing lipid peroxide, and activates its transcriptional activity, resulting in decreased lipid peroxide and ferroptosis. Subsequently, we showed that NeuroD1/GPX4-mediated ferroptosis resistance was crucial for HCC cell tumorigenic potential. These findings not only identify NeuroD1 as a regulator of tumor cell ferroptosis resistance but also reveal a novel molecular mechanism underlying the oncogenic function of NeuroD1. Furthermore, our findings suggest the potential of targeting NeuroD1 in antitumor therapy.

Regulation of phosphoglycerate kinase 1 and its critical role in cancer

Cells that undergo normal differentiation mainly rely on mitochondrial oxidative phosphorylation to provide energy, but most tumour cells rely on aerobic glycolysis. This phenomenon is called the "Warburg effect". Phosphoglycerate kinase 1 (PGK1) is a key enzyme in aerobic glycolysis. PGK1 is involved in glucose metabolism as well as a variety of biological activities, including angiogenesis, EMT, mediated autophagy initiation, mitochondrial metabolism, DNA replication and repair, and other processes related to tumorigenesis and development. Recently, an increasing number of studies have proven that PGK1 plays an important role in cancer. In this manuscript, we discussed the effects of the structure, function, molecular mechanisms underlying PGK1 regulation on the initiation and progression of cancer. Additionally, PGK1 is associated with chemotherapy resistance and prognosis in tumour patients. This review presents an overview of the different roles played by PGK1 during tumorigenesis, which will help in the design of experimental studies involving PGK1 and enhance the potential for the use of PGK1 as a therapeutic target in cancer. Video Abstract.

Regulation of Autophagy via Carbohydrate and Lipid Metabolism in Cancer

Metabolic changes are an important component of tumor cell progression. Tumor cells adapt to environmental stresses via changes to carbohydrate and lipid metabolism. Autophagy, a physiological process in mammalian cells that digests damaged organelles and misfolded proteins via lysosomal degradation, is closely associated with metabolism in mammalian cells, acting as a meter of cellular ATP levels. In this review, we discuss the changes in glycolytic and lipid biosynthetic pathways in mammalian cells and their impact on carcinogenesis via the autophagy pathway. In addition, we discuss the impact of these metabolic pathways on autophagy in lung cancer.

PGK1 modulates balance between pro- and anti-inflammatory cytokines by interacting with ITI-H4

Inter-α-trypsin inhibitor heavy chain 4 (ITI-H4) is one of the acute phase proteins and is mainly related with inflammatory diseases such as bacterial bloodstream infection and recurrent pregnancy loss (RPL). In a previous study, ITI-H4 was reported to be cleaved by kallikrein B1 (KLKB1) and its cleaved form induces the imbalance between pro- and anti-inflammatory cytokines. Therefore, in this study, putative substrates of ITI-H4 were isolated by immunoprecipitation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) analysis. Of those, phosphoglycerate kinase 1 (PGK1) was found to be a binding protein of ITI-H4. PGK1 increases the level of ITI-H4 expression and blocks the cleavage of ITI-H4 mediated by KLKB1. It also inhibits pro-inflammatory response by inhibiting the JAK2/STAT3 signaling pathway. Therefore, PGK1, a novel binding partner of ITI-H4, is expected to have cellular functions in the pathogenesis of ITI-H4-related inflammatory diseases.

Exploring the role of sphingolipid-related genes in clinical outcomes of breast cancer

Background

Despite tremendous advances in cancer research, breast cancer (BC) remains a major health concern and is the most common cancer affecting women worldwide. Breast cancer is a highly heterogeneous cancer with potentially aggressive and complex biology, and precision treatment for specific subtypes may improve survival in breast cancer patients. Sphingolipids are important components of lipids that play a key role in the growth and death of tumor cells and are increasingly the subject of new anti-cancer therapies. Key enzymes and intermediates of sphingolipid metabolism (SM) play an important role in regulating tumor cells and further influencing clinical prognosis.

Methods

We downloaded BC data from the TCGA database and GEO database, on which we performed in depth single-cell sequencing analysis (scRNA-seq), weighted co-expression network analysis, and transcriptome differential expression analysis. Then seven sphingolipid-related genes (SRGs) were identified using Cox regression, least absolute shrinkage, and selection operator (Lasso) regression analysis to construct a prognostic model for BC patients. Finally, the expression and function of the key gene PGK1 in the model were verified by in vitro experiments.

Results

This prognostic model allows for the classification of BC patients into high-risk and low-risk groups, with a statistically significant difference in survival time between the two groups. The model is also able to show high prediction accuracy in both internal and external validation sets. After further analysis of the immune microenvironment and immunotherapy, it was found that this risk grouping could be used as a guide for the immunotherapy of BC. The proliferation, migration, and invasive ability of MDA-MB-231 and MCF-7 cell lines were dramatically reduced after knocking down the key gene PGK1 in the model through cellular experiments.

Conclusion

This study suggests that prognostic features based on genes related to SM are associated with clinical outcomes, tumor progression, and immune alterations in BC patients. Our findings may provide insights for the development of new strategies for early intervention and prognostic prediction in BC.