Thymidine kinase 1 drives hepatocellular carcinoma in enzyme-dependent and -independent manners

Identification of pyrimidine metabolism-based molecular subtypes and prognostic signature to predict immune landscape and guide clinical treatment in prostate cancer

BACKGROUND

We previously described the enrichment of plasma exosome metabolites in CRPC, PCa, and TFC cohorts, and found significant differences in pyrimidine metabolites. The PMGs is associated with the clinical prognosis of several cancers, but its biological role in PCa is still unclear.

METHODS

This study extracted 98 reliable PMGs, and analyzed their somatic mutations, expression levels, and prognostic significance. Unsupervised clustering was applied to classify patients with PCa into clusters based on six PMGs that were related to the prognosis of PCa. The TME, gene mutations, and immune escape ability were compared among the clusters. A scoring algorithm based on prognostic PMGs, referred to as the PMGscore, was developed. TK1 was identified and the biological functions of TK1 were determined using loss-of-function experiments. RNA sequencing was subsequently performed to determine the molecules associated with the underlying mechanisms of TK1 function.

RESULTS

In total, six out of 98 PMGs simultaneously exhibited differential expression in PCa and were correlated with BCR. Patients were clustered into two clusters according to the expression levels of these six PMGs, which reflected distinct clinical outcomes and immune cell infiltration characteristics. Clinical features, tumor prognosis, and functional annotation were analyzed. Subsequently, we constructed a prognostic signature using these six PMGs. In combination with other clinical traits, we found that the six PMGs' prognostic signature was an independent prognostic factor for patients with PCa. Finally, we found that the expression of TK1 was higher in CRPC tissues than in PCa tissues in three GEO datasets. The results indicated that TK1 promotes the growth and metastasis of PCa cells.

CONCLUSIONS

We provide evidence for a PMG signature for PCa patients to accurately predict clinical prognosis. TK1 plays crucial roles in the progression of PCa cells and can be used as a potential therapeutic target for CRPC.

ERK-USP9X-coupled regulation of thymidine kinase 1 promotes both its enzyme activity-dependent and its enzyme activity-independent functions for tumor growth

Thymidine kinase 1 (TK1), a crucial enzyme in DNA synthesis, is highly expressed in various cancers. However, the mechanisms underlying its elevated expression and the implications for tumor metabolism remain unclear. Here we demonstrate that activation of growth factor receptors enhances TK1 expression. Treatment with epidermal growth factor or insulin-like growth factor 1 induces the binding of ERK1/2 to TK1 and subsequent TK1 S13/231 phosphorylation by ERK1/2. This modification recruits ubiquitin carboxyl-terminal hydrolase 9X to deubiquitylate TK1, preventing its proteasomal degradation. Stabilized TK1 not only enhances its enzyme activity-dependent deoxythymidine monophosphate production for DNA synthesis but also promotes glycolysis independently of its enzymatic activity by upregulating phosphofructokinase/fructose bisphosphatase type 3 expression. This dual role of TK1 drives the proliferation of human hepatocellular carcinoma cells and liver tumor growth in mice. Our findings reveal a crucial mechanism by which growth factors promote tumor development through TK1-mediated DNA synthesis and glycolysis and highlight TK1 as a potential molecular target for cancer treatment.

PRPS2 enhances RNA m6A methylation by stimulating SAM synthesis through enzyme-dependent and independent mechanisms

Cancer cells exploit altered metabolic pathways to dynamically regulate epigenetic methylation and thus promote tumorigenesis and metastasis. In various human cancers, such as lung adenocarcinoma, the level of a key cellular metabolite, S-adenosylmethionine (SAM), is prominently upregulated for RNA hypermethylation as the methyl donor. However, the specific mechanisms by which cancer cells produce SAM to sustain RNA methylation remain elusive. Here, we demonstrate that PRPS2, a phosphoribosyl pyrophosphate synthetase isoform involved in the first and rate-limiting step of the purine biosynthesis pathway, exhibits distinct oncogenic functionality in regulating RNA methylation, unlike its homolog PRPS1. PRPS2 utilizes four non-conserved key residues to bypass the typical ADP/GDP allosteric feedback inhibition, enabling sustained excess production of newly synthesized ATP. Moreover, PRPS2 stabilizes methionine adenosyltransferase 2 A (MAT2A) through direct interactions to positively stimulate ATP utilization and SAM synthesis for RNA m6A specific methylation via the WTAP/METTL3/METTL14 methyltransferase complex, thereby promoting lung tumorigenesis. Our study links nucleotide biosynthesis with RNA epigenetics in cancer progression through the PRPS2-MAT2A-WTAP/METTL3/METTL14 axis, and elucidates both enzyme-dependent and independent functions of PRPS2. These findings have significant implications for developing targeted therapies for cancers associated with PRPS2 abnormalities.

TRIM38 Suppresses the Progression of Colorectal Cancer via Enhancing CCT6A Ubiquitination to Inhibit the MYC Pathway

Emerging evidence reveals the pivotal function of tripartite motif protein (TRIM) in colorectal cancer (CRC). However, the precise function of TRIM38 and its underlying mechanism in CRC remains to be elucidated, especially regarding its putative ubiquitination function. Here, it is identified that TRIM38 is downregulated in CRC tissues by DNA hypermethylation of its promoter. Further analysis demonstrates that decreased TRIM38 is correlated with unfavorable clinical features and poor prognosis. Moreover, TRIM38 functions as a tumor suppressor by inhibiting cell proliferation, metastasis, and AOM/DSS-induced tumorigenesis in CRC cells. Mechanistically, TRIM38 binds to the substrate protein CCT6A, leading to the degradation and K48-linked ubiquitination of CCT6A at the K127/K138 residues. The elevation of CCT6A protein level caused by TRIM38 downregulation diminishes the degradation of c-Myc protein, thereby activating the MYC pathway. The study elucidates a novel mechanism of TRIM38/CCT6A/c-Myc axis regulating CRC, potentially offering a new therapeutic target for its treatment.

eIF3f promotes tumour malignancy by remodelling fatty acid biosynthesis in hepatocellular carcinoma

BACKGROUND & AIMS

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC). Elucidating the molecules that influence fatty acid metabolism in HCC is important for developing precision therapies. However, uncovering the precise molecular mechanisms underlying changes in fatty acid metabolism in tumour cells is challenging. In this study, we aimed to determine the characteristics of fatty acid metabolism in HCC.

METHODS

We employed organoid models, single-cell RNA sequencing, and spatial transcriptomics to identify key genes involved in tumour fatty acid metabolism. Metabolomics, proteomics, metabolic flux analysis, and transmission electron microscopy were utilized to evaluate this metabolic process. Tumour malignancy was characterized using multi-species models. Changes in the immune microenvironment were analysed by time-of-flight mass cytometry and multiplexed immunohistochemistry. Gene knockdown targeting the liver was achieved using lipid nanoparticles.

RESULTS

Eukaryotic translation initiation factor 3 subunit f (eIF3f) is upregulated in HCC tissues and is associated with poor prognosis. eIF3f directly interacted with and stabilised long chain acyl CoA synthetase 4 (ACSL4) through K48-linked deubiquitination, promoting fatty acid biosynthesis and malignancy. The increased fatty acid levels in the tumour microenvironment indirectly reduced CD8+ T-cell infiltration. In addition, phosphorylated eIF3f enhanced the interaction between eIF3f and ACSL4.

CONCLUSIONS

Targeting the eIF3f-ACSL4-fatty acid biosynthesis axis could decelerate the progression of HCC and enhance anti-programmed cell death-1 efficacy, implicating eIF3f as a potential target for precision therapy in HCC.

IMPACT AND IMPLICATIONS

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC), yet the underlying mechanisms involved remain unclear. Here, we found that eIF3f is upregulated in HCC and is associated with poor prognosis. eIF3f interacts with and stabilizes ACSL4, thereby promoting fatty acid biosynthesis. Additionally, increased fatty acid levels reduce CD8+ T-cell infiltration and activation. These findings are of significant importance for clinicians and researchers in the field of HCC treatment, as eIF3f inhibition combined with anti-PD-1 therapy significantly improved anti-tumour efficacy in a mouse model and could offer therapeutic benefits for patients. These findings have practical implications, as eIF3f could serve as a novel therapeutic target in HCC. However, further clinical studies are needed to confirm the efficacy of eIF3f targeting in human patients.

Hypomethylation induced overexpression of PLOD3 facilitates colorectal cancer progression through TM9SF4-mediated autophagy

Colorectal cancer (CRC) ranks among the primary causes of human mortality globally. Numerous studies have highlighted the significant role of PLOD3 in the progression of various cancers. However, the exact function and underlying mechanisms of PLOD3 in CRC remains incompletely understood. To investigate the expression of PLOD3, qRT‒PCR, immunohistochemistry and western blotting were utilized to analyze the expression of PLOD3 in CRC tissues and adjacent normal tissues. Functional assays were conducted to assess the roles of PLOD3 both in vitro and in vivo. To elucidate the potential mechanism of PLOD3 in CRC, a range of techniques, including coimmunoprecipitation, immunofluorescence, CHX pulse-chase, and ubiquitination assays were used. As the results indicated, hypomethylation of the PLOD3 promoter leads to its over- expression in CRC, and elevated PLOD3 levels are associated with a poor prognosis. Both in vitro and in vivo models demonstrated that PLOD3 enhances CRC cell proliferation, invasion, and migration. Furthermore, through mechanistic studies, TM9SF4 was identified as a protein that interacts with PLOD3 and contributes to CRC progression by promoting autophagy. Additionally, PLOD3 could be secreted by CRC cells and secreted PLOD3 could promote CRC cells migration and invasion. These results demonstrated that PLOD3 promotes CRC progression through the PLOD3/TM9SF4 axis and could be a potential biomarker and treatment target for CRC.

PRDX6 Prevents NNMT Ubiquitination and Degradation as a Nonenzymatic Mechanism to Promote Ovarian Cancer Progression

Cancer cells cope with oxidative stress for their proliferation and metastasis by equipping antioxidant systems, among which the antioxidant enzymes peroxiredoxins (PRDXs) play crucial roles. However, whether PRDXs exhibit nonenzymatic functions remains unclear. Here, it is shown that the 1-cysteine PRDX (PRDX6) upregulates nicotinamide N-methyltransferase (NNMT) to promote the growth and metastasis of ovarian cancer cells, independently of PRDX6's enzymatic activities. Mechanistically, PRDX6 interacts with NNMT to prevent its binding to the E3 ubiquitin ligase tripartite-motif protein 56 (TRIM56), leading to the inhibition of NNMT ubiquitination at lysine 23 and 210 and suppression of subsequent proteasomal degradation. In addition, PRDX6-mediated NNMT upregulation activates mitogen-activated protein kinase (MAPK) signaling, thereby promoting the growth and metastasis of ovarian cancer cells. Notably, PRDX6 overexpression is associated with higher NNMT protein levels in human ovarian cancer tissues and is predictive of poor prognosis of ovarian cancer patients. Overall, the findings illustrate a critical oncogenic mechanism of the antioxidant enzyme PRDX6 in promoting ovarian cancer progression beyond its enzymatic mechanisms.

A stable thymidine kinase 1 tetramer for improved quality control of serum level quantification

DNA synthesis is a critical process for cell growth and division. In cancer patients, an enzyme called thymidine kinase 1 (TK1) is often elevated in the blood, making it a valuable biomarker for cancer diagnosis and treatment. However, previous studies have shown that recombinant TK1 can exist in unstable mixtures of tetramers and dimers, leading to inconsistent results and potentially affecting accuracy. To address this issue, we hypothesized that incorporating tetrameric coiled-coil peptides could enhance TK1 self-assembly into stable tetramers without requiring additional adenosine triphosphate. In this study, we successfully expressed a recombinant TK1 tetramer protein in the Escherichia coli system. We optimized the induction conditions, significantly increasing protein expression levels, functionality, and solubility. Size exclusion chromatography confirmed the formation of a tetrameric structure in the expressed TK1 protein, with a molecular weight of 127.2 KDa, consistent with our expectations. We also found that the TK1 tetramer exhibited higher affinity with anti-TK1 IgY than wild-type TK1, as shown by enzyme-linked immunosorbent assay experiments. Moreover, the TK1 tetramer demonstrated good stability against heating, freeze-thawing and lyophilization with almost no immunoactivity lost. These findings suggest that recombinant TK1 tetramers have the potential to serve as calibrators in diagnostic assay kits, becoming promising candidates for quality control of clinical laboratory and in vitro diagnostic reagents.

Proteomic Characterization of Liver Cancer Cells Treated with Clinical Targeted Drugs for Hepatocellular Carcinoma

Background/Objectives: Hepatocellular carcinoma (HCC) remains a significant global health concern, primarily due to the limited efficacy of targeted therapies, which are often compromised by drug resistance and adverse side effects. Methods: In this study, we utilized a Tandem Mass Tag (TMT)-based quantitative proteomic approach to analyze global protein expression and serine/threonine/tyrosine (S/T/Y) phosphorylation modifications in HepG2 cells following treatment with three clinically relevant hepatocellular carcinoma-targeted agents: apatinib, regorafenib, and lenvatinib. Results: Utilizing KEGG pathway enrichment analysis, biological process enrichment analysis, and protein interaction network analysis, we elucidated the common and specific metabolic pathways, biological processes, and protein interaction regulatory networks influenced by three liver cancer therapeutics. The study additionally proposed potential combinational treatment strategies, highlighting a possible synergistic interaction between HCC-targeted drugs and the DNA methyltransferase inhibitor. Furthermore, through the integration of clinical phosphorylation site data, we identified several phosphorylation sites that exhibited higher abundance in tumor tissues compared to adjacent non-tumor tissues. These sites were associated with poor prognosis and elevated functional scores. Conclusions: In summary, this study conducted an in-depth analysis of the molecular alterations in proteins and phosphorylation modifications induced by clinical HCC-targeted drugs, predicting drug combination strategies and therapeutic targets.

CancerSCEM 2.0: an updated data resource of single-cell expression map across various human cancers

The field of single-cell RNA sequencing (scRNA-seq) has advanced rapidly in the past decade, generating significant amounts of valuable data for researchers to study complex tumor profiles. This data is crucial for gaining innovative insights into cancer biology. CancerSCEM (https://ngdc.cncb.ac.cn/cancerscem) is a public resource that integrates, analyzes and visualizes scRNA-seq data related to cancer, and it provides invaluable support to numerous cancer-related studies. With CancerSCEM 2.0, scRNA-seq data have increased from 208 to 1466 datasets, covering tumor, matching-normal and peripheral blood samples across 127 research projects and 74 cancer types. The new version of this resource enhances transcriptome analysis by adding copy number variation evaluation, transcription factor enrichment, pseudotime trajectory construction, and diverse biological feature scoring. It also introduces a new cancer metabolic map at the single-cell level, providing an intuitive understanding of metabolic regulation across different cancer types. CancerSCEM 2.0 has a more interactive analysis platform, including four modules and 14 analytical functions, allowing researchers to perform cancer scRNA-seq data analyses in various dimensions. These enhancements are expected to expand the usability of CancerSCEM 2.0 to a broader range of cancer research and clinical applications, potentially revolutionizing our understanding of cancer mechanisms and treatments.

Loss of Carbamoyl Phosphate Synthetase 1 Potentiates Hepatocellular Carcinoma Metastasis by Reducing Aspartate Level

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide. Numerous studies have shown that metabolic reprogramming is crucial for the development of HCC. Carbamoyl phosphate synthase 1 (CPS1), a rate-limiting enzyme in urea cycle, is an abundant protein in normal hepatocytes, however, lacking systemic research in HCC. It is found that CPS1 is low-expressed in HCC tissues and circulating tumor cells, negatively correlated with HCC stage and prognosis. Further study reveals that CPS1 is a double-edged sword. On the one hand, it inhibits the activity of phosphatidylcholine-specific phospholipase C to block the biosynthesis of diacylglycerol (DAG), leading to the downregulation of the DAG/protein kinase C pathway to inhibit invasion and metastasis of cancer cells. On the other hand, CPS1 promotes cell proliferation by increasing intracellular S-adenosylmethionin to enhance the m6A modification of solute carrier family 1 member 3 mRNA, a key transporter for aspartate intake. Finally, CPS1 overexpressing adeno-associated virus can dampen HCC progression. Collectively, this results uncovered that CPS1 is a switch between HCC proliferation and metastasis by increasing intracellular aspartate level.

Oncogenic cholesterol rewires lipid metabolism in hepatocellular carcinoma via the CSNK2A1-IGF2R Ser2484 axis

INTRODUCTION

Alcohol consumption and hepatitis B virus (HBV) infection are common risk factors for hepatocellular carcinoma (HCC). However, few studies have focused on elucidating the mechanisms of HCC with combined alcohol and HBV etiology.

OBJECTIVES

We aimed to investigate the molecular features of alcohol and HBV on HCC and to seek out potential therapeutic strategies.

METHODS

Two independent cohorts of HCC patients (n = 539 and n = 140) were included to investigate HCC with synergetic alcohol and HBV (AB-HCC) background. Patient-derived cell lines, organoids, and xenografts were used to validate the metabolic fragile. High-throughput drug screening (1181 FDA-approved anticancer drugs) was leveraged to explore the potential therapeutic agents.

RESULTS

Here, we delineated AB-HCC as a distinctive metabolic subtype, hallmarked by oncogenic cholesterol, through the integration of clinical cohorts, proteomics, phosphoproteomics, and spatial transcriptome. Mechanistically, our findings revealed that cholesterol directly binds to CSNK2A1 (Casein Kinase 2 Alpha 1), augmenting its kinase activity and leading to phosphorylation of IGF2R (Insulin-Like Growth Factor 2 Receptor) at Ser2484. This cascade rewires lipid-driven mitochondrial oxidative phosphorylation, spawns reactive oxygen species measured by malondialdehyde assay, and perpetuates a positive feedback loop for cholesterol biosynthesis, ultimately culminating in tumorigenesis. Initial transcriptional activation of CSNK2A1 is driven by upregulation of RAD21 in AB-HCC. Our cholesterol profiling exposes AB-HCC's compensatory mechanism of AB-HCC, which capitalizes on both uptake and biosynthesis of cholesterol to confer survival edge. Moreover, high-throughput drug screening coupled with in vivo validation has uncovered the susceptibilities of AB-HCC, which can be effectively addressed by a combination of dietary cholesterol restriction and oral administration of Fostamatinib. The CSNK2A1-mediated cholesterol biosynthesis pathway has been implicated in various cancers characterized by cholesterol metabolism.

CONCLUSION

These findings not only pinpoint the oncogenic metabolite cholesterol as a hidden culprit in AB-HCC subtype, but also enlighten a novel combination strategy to rejuvenate tumor metabolism.

Hepatocyte-derived Igκ promotes HCC progression by stabilizing electron transfer flavoprotein subunit α to facilitate fatty acid β-oxidation

BACKGROUND

Lipid metabolism dysregulation is a key characteristic of hepatocellular carcinoma (HCC) onset and progression. Elevated expression of immunoglobulin (Ig), especially the Igκ free light chain with a unique Vκ4-1/Jκ3 rearrangement in cancer cells, is linked to increased malignancy and has been implicated in colon cancer tumorigenesis. However, the role of Igκ in HCC carcinogenesis remains unclear. The aim of this study was to elucidate the pivotal roles of hepatocyte-derived Igκ in HCC development.

METHODS

The rearrangement sequence and expression level of hepatocyte-derived Igκ in HCC cells were determined via RT-PCR, Sanger sequencing, immunohistochemistry, and western blot analysis. The function of Igκ in HCC tumorigenesis was assessed by silencing Igκ using siRNA or gRNA in various HCC cell lines. To assess the role of Igκ in HCC pathogenesis in vivo, a mouse model with hepatocyte-specific Igκ knockout and diethylnitrosamine (DEN) and carbon tetrachloride (CCL4)-induced HCC was utilized. The molecular mechanism by which Igκ affects HCC tumorigenesis was investigated through multiomics analyses, quantitative real-time PCR, immunoprecipitation, mass spectrometry, immunofluorescence, and metabolite detection.

RESULTS

We confirmed that Igκ, especially Vκ4-1/Jκ3-Igκ, is highly expressed in human HCC cells. Igκ depletion inhibited HCC cell proliferation and migration in vitro, and hepatocyte-specific Igκ deficiency ameliorated HCC progression in mice with DEN and CCL4-induced HCC in vivo. Mechanistically, Vκ4-1/Jκ3-Igκ interacts with electron transfer flavoprotein subunit α (ETFA), delaying its protein degradation. Loss of Igκ led to a decrease in the expression of mitochondrial respiratory chain complexes III and IV, resulting in aberrant fatty acid β-oxidation (FAO) and lipid accumulation, which in turn inhibited HCC cell proliferation and migration.

CONCLUSION

Our findings indicate that the Igκ/ETFA axis deregulates fatty acid β-oxidation, contributing to HCC progression, which suggests that targeting fatty acid metabolism may be an effective HCC treatment strategy. The results of this study suggest that hepatocyte-derived Vκ4-1/Jκ3-Igκ may serve as a promising therapeutic target for HCC.

Pan-cancer analysis reveals that TK1 promotes tumor progression by mediating cell proliferation and Th2 cell polarization

BACKGROUND

TK1 (Thymidine kinase 1) is a member of the thymidine kinase family and has been observed to be significantly upregulated in a variety of cancer types. However, the exact roles of TK1 in tumor progression and the tumor immune microenvironment are not fully understood. This study aims to investigate the comprehensive involvement of TK1 in pan-cancer through the utilization of bioinformatics analysis, validation of pathological tissue samples, and in vitro experimental investigations.

METHODS

The expression profiles together with diagnostic and prognostic role of TK1 in pan-cancer were investigated though TCGA, TARGET, GTEx, and CPTAC databases. The single-sample gene set enrichment analysis (ssGSEA) and single-cell sequencing datasets were used to examine the relationship between TK1 and immune infiltration. The expression of TK1 were verified in hepatocellular carcinoma (HCC) through qPCR, western blotting and immunohistochemical assays. The proliferative capacity of HCC cell lines was assessed through CCK-8 and colony formation assays, while cytokine levels were measured via ELISA. Furthermore, flow cytometry was utilized to analyze cell cycle distribution and the proportions of Th2 cells.

RESULTS

TK1 was overexpressed in most cancers and demonstrated significant diagnostic and prognostic value. Among the various immune cells in pan-cancer, Th2 cells exhibited the closest association with TK1. Furthermore, the single-cell atlas provided insights into the distribution and proportion of TK1 in immune cells of HCC. In vitro experiments revealed an elevated expression of TK1 in HCC tissue and cell lines, and its role in influencing HCC cell proliferation by regulating G0/G1 phase arrest. Additionally, TK1 in cancer cells was found to potentially modulate Th2 cell polarization through the chemokine CCL5.

CONCLUSION

TK1 holds immense potential as a biomarker for pan-cancer diagnosis and prognosis. Additionally, targeting the expression of TK1 represents a promising therapeutic approach that can enhance the efficacy of current anti-tumor immunotherapy by modulating Th2 cell polarization and multiple mechanisms.

Deficiency of betaine-homocysteine methyltransferase activates glucose-6-phosphate dehydrogenase (G6PD) by decreasing arginine methylation of G6PD in hepatocellular carcinogenesis

Betaine-homocysteine methyltransferase (BHMT) regulates protein methylation and is correlated with tumorigenesis; however, the effects and regulation of BHMT in hepatocarcinogenesis remain largely unexplored. Here, we determined the clinical significance of BHMT in the occurrence and progression of hepatocellular carcinoma (HCC) using tissue samples from 198 patients. BHMT was to be frequently found (86.6%) expressed at relatively low levels in HCC tissues and was positively correlated with the overall survival of patients with HCC. Bhmt overexpression effectively suppressed several malignant phenotypes in hepatoma cells in vitro and in vivo, whereas complete knockout of Bhmt (Bhmt-/-) produced the opposite effect. We combined proteomics, metabolomics, and molecular biological strategies and detected that Bhmt-/- promoted hepatocarcinogenesis and tumor progression by enhancing the activity of glucose-6-phosphate dehydrogenase (G6PD) and PPP metabolism in DEN-induced HCC mouse and subcutaneous tumor-bearing models. In contrast, restoration of Bhmt with an AAV8-Bhmt injection or pharmacological inhibition of G6PD attenuated hepatocarcinogenesis. Additionally, coimmunoprecipitation identified monomethylated modifications of the G6PD, and BHMT regulated the methylation of G6PD. Protein sequence analysis, generation and application of specific antibodies, and site-directed mutagenesis indicated G6PD methylation at the arginine residue 246. Furthermore, we established bidirectionally regulated BHMT cellular models combined with methylation-deficient G6PD mutants to demonstrate that BHMT potentiated arginine methylation of G6PD, thereby inhibiting G6PD activity, which in turn suppressed hepatocarcinogenesis. Taken together, this study reveals a new methylation-regulatory mechanism in hepatocarcinogenesis owing to BHMT deficiency, suggesting a potential therapeutic strategy for HCC treatment.

The role and mechanism of SUMO modification in liver disease

Liver disease affects millions of people in the world, and China has the highest prevalence of liver disease in the world. Small ubiquitin-related modifier (SUMO) modification is a highly conserved post-translational modification of proteins. They are widely expressed in a variety of tissues, including the heart, liver, kidney and lung. SUMOylation of protein plays a key role in the occurrence and development of liver disease. Therefore, this study reviewed the effects of SUMO protein on non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), viral hepatitis, hepatic fibrosis (HF), hepatocellular carcinoma (HCC), and other liver diseases to provide novel strategies for targeted treatment of liver disease.

Metabolic reprogramming in hepatocellular carcinoma: a bibliometric and visualized study from 2011 to 2023

Background and aims

Metabolic reprogramming has been found to be a typical feature of tumors. Hepatocellular carcinoma (HCC), a cancer with high morbidity and mortality, has been extensively studied for its metabolic reprogramming-related mechanisms. Our study aims to identify the hotspots and frontiers of metabolic reprogramming research in HCC and to provide guidance for future scientific research and decision-making in HCC metabolism.

Methods

Relevant studies on the metabolic reprogramming of HCC were derived from the Web of Science Core Collection (WoSCC) database up until November 2023. The bibliometrix tools in R were used for scientometric analysis and visualization.

Results

From 2011 to 2023, a total of 575 publications were obtained from WoSCC that met the established criteria. These publications involved 3,904 researchers and 948 organizations in 37 countries, with an average annual growth rate of 39.11% in research. These studies were published in 233 journals, with Cancers (n = 29) ranking first, followed by Frontiers in Oncology (n = 20) and International Journal of Molecular Sciences (n = 19). The top ten journals accounted for 26% of the 575 studies. The most prolific authors were Wang J (n = 14), Li Y (n = 12), and Liu J (n = 12). The country with the most publications is China, followed by the United States, Italy, and France. Fudan University had the largest percentage of research results with 15.48% (n = 89). Ally A's paper in Cell has the most citations. A total of 1,204 keywords were analyzed, with the trend themes such as "glycolysis," "tumor microenvironment," "Warburg effect," "mitochondria," "hypoxia ," etc. Co-occurrence network and cluster analysis revealed the relationships between keywords, authors, publications, and journals. Moreover, the close collaboration between countries in this field was elucidated.

Conclusion

This bibliometric and visual analysis delves into studies related to metabolic reprogramming in HCC between 2012 and 2023, elucidating the characteristics of research in this field, which has gradually moved away from single glycolipid metabolism studies to the integration of overall metabolism in the body, pointing out the trend of research topics, and the dynamics of the interaction between the tumor microenvironment and metabolic reprogramming will be the future direction of research, which provides blueprints and inspirations for HCC prevention and treatment programs to the researchers in this field.

Systematic Review Registration: [https://www.bibliometrix.org].

Sanguinarine Induces Necroptosis of HCC by Targeting PKM2 Mediated Energy Metabolism

BACKGROUNDS

Abnormal metabolism is the hallmark of hepatocellular carcinoma. Targeting energy metabolism has become the major focus of cancer therapy. The natural product, sanguinarine, displays remarkable anti-tumor properties by disturbing energy homeostasis; however, the underlying mechanism has not yet been elucidated.

METHODS

The anticancer activity of sanguinarine was determined using CCK-8 and colony formation assay. Morphological changes of induced cell death were observed under electron microscopy. Necroptosis and apoptosis related markers were detected using western blotting. PKM2 was identified as the target by transcriptome sequencing. Molecular docking assay was used to evaluate the binding affinity of sanguinarine to the PKM2 molecule. Furthermore, Alb-CreERT2; PKM2loxp/loxp; Rosa26RFP mice was used to construct the model of HCC-through the intervention of sanguinarine in vitro and in vivo-to accurately explore the regulation effect of sanguinarine on cancer energy metabolism.

RESULTS

Sanguinarine inhibited tumor proliferation, metastasis and induced two modes of cell death. Molecular docking of sanguinarine with PKM2 showed appreciable binding affinity. PKM2 kinase activity and aerobic glycolysis rate declined, and mitochondrial oxidative phosphorylation was inhibited by sanguinarine application; these changes result in energy deficits and lead to necroptosis. Additionally, sanguinarine treatment prevents the translocation of PKM2 into the nucleus and suppresses the interaction of PKM2 with β-catenin; the transcriptional activity of PKM2/β-catenin signaling and its downstream genes were decreased.

CONCLUSIONS

Sanguinarine showed remarkable anti-HCC activity via regulating energy metabolism by PKM2/β-catenin signaling. On the basis of these investigations, we propose that sanguinarine might be considered as a promising compound for discovery of anti-HCC drugs.

Intricate effects of post-translational modifications in liver cancer: mechanisms to clinical applications

Liver cancer is a significant global health challenge, with hepatocellular carcinoma (HCC) being the most prevalent form, characterized by high incidence and mortality rates. Despite advances in targeted therapies and immunotherapies, the prognosis for advanced liver cancer remains poor. This underscores the urgent need for a deeper understanding of the molecular mechanisms underlying HCC to enable early detection and the development of novel therapeutic strategies. Post-translational modifications (PTMs) are crucial regulatory mechanisms in cellular biology, affecting protein functionality, interactions, and localization. These modifications, including phosphorylation, acetylation, methylation, ubiquitination, and glycosylation, occur after protein synthesis and play vital roles in various cellular processes. Recent advances in proteomics and molecular biology have highlighted the complex networks of PTMs, emphasizing their critical role in maintaining cellular homeostasis and disease pathogenesis. Dysregulation of PTMs has been associated with several malignant cellular processes in HCC, such as altered cell proliferation, migration, immune evasion, and metabolic reprogramming, contributing to tumor growth and metastasis. This review aims to provide a comprehensive understanding of the pathological mechanisms and clinical implications of various PTMs in liver cancer. By exploring the multifaceted interactions of PTMs and their impact on liver cancer progression, we highlight the potential of PTMs as biomarkers and therapeutic targets. The significance of this review lies in its potential to inform the development of novel therapeutic approaches and improve prognostic tools for early intervention in the fight against liver cancer.

CRISPR/Cas9 screen reveals that targeting TRIM34 enhances ferroptosis sensitivity and augments immunotherapy efficacy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent malignancy characterized by complex heterogeneity and drug resistance. Resistance to ferroptosis is closely related to the progression of HCC. While HCC tumors vary in their sensitivity to ferroptosis, the precise factors underlying this heterogeneity remain unclear. In this study, we sought to elucidate the mechanisms that contribute to ferroptosis resistance in HCC. Whole-genome CRISPR/Cas9 screen using a subtoxic concentration (IC20) of ferroptosis inducer erastin in the HCC cell line Huh7 revealed TRIM34 as a critical driver of ferroptosis resistance in HCC. Further investigation revealed that TRIM34 suppresses ferroptosis in HCC cells, promoting their proliferation, migration, and invasion both in vitro and in vivo. Furthermore, TRIM34 expression is elevated in HCC tumor tissues, correlating with a poor prognosis. Mechanistically, TRIM34 directly interacts with Up-frameshift 1 (UPF1), a core component of the nonsense-mediated mRNA decay (NMD) pathway, to promote its ubiquitination and degradation. This interaction suppresses GPX4 transcript degradation, thus promoting the protein levels of this critical ferroptosis suppressor in HCC. In light of the close crosstalk between ferroptosis and the adaptive immune response in cancer, HCC cells with targeting knockdown of TRIM34 exhibited an improved response to anti-PD-1 treatment. Taken together, the TRIM34/UPF1/GPX4 axis mediates ferroptosis resistance in HCC, thereby promoting malignant phenotypes. Targeting TRIM34 may thus represent a promising new strategy for HCC treatment.

Hypomethylation-enhanced CRTC2 expression drives malignant phenotypes and primary resistance to immunotherapy in hepatocellular carcinoma

The cyclic AMP-responsive element-binding protein (CREB)-regulated transcription coactivator 2 (CRTC2) is a crucial regulator of hepatic lipid metabolism and gluconeogenesis and correlates with tumorigenesis. However, the mechanism through which CRTC2 regulates hepatocellular carcinoma (HCC) progression is largely unknown. Here, we found that increased CRTC2 expression predicted advanced tumor grade and stage, as well as worse prognosis in patients with HCC. DNA promoter hypomethylation led to higher CRTC2 expression in HCC. Functionally, CRTC2 contributed to HCC malignant phenotypes through the activated Wnt/β-catenin pathway, which could be abrogated by the small-molecular inhibitor XAV-939. Moreover, Crtc2 facilitated tumor growth while concurrently downregulating the PD-L1/PD-1 axis, resulting in primary resistance to immunotherapy. In immunocompetent mice models of HCC, targeting Crtc2 in combination with anti-PD-1 therapy prominently suppressed tumor growth by synergistically enhancing responsiveness to immunotherapy. Collectively, targeting CRTC2 might be a promising therapeutic strategy to sensitize immunotherapy in HCC.

The Interplay of Acetylation and Ubiquitination Controls PRMT1 Homeostasis

PRMT1 plays many important roles in both normal and disease biology, thus understanding it's regulation is crucial. Herein, we report the role of p300-mediated acetylation at K228 in triggering PRMT1 degradation through FBXL17-mediated ubiquitination. Utilizing mass-spectrometry, cellular biochemistry, and genetic code-expansion technologies, we elucidate a crucial mechanism independent of PRMT1 transcript levels. These results underscore the significance of acetylation in governing protein stability and expand our understanding of PRMT1 homeostasis. By detailing the molecular interplay between acetylation and ubiquitination involved in PRMT1 degradation, this work contributes to broader efforts in deciphering post-translational mechanisms that influence protein homeostasis.

FBXO7 ubiquitinates PRMT1 to suppress serine synthesis and tumor growth in hepatocellular carcinoma

Cancer cells are often addicted to serine synthesis to support growth. How serine synthesis is regulated in cancer is not well understood. We recently demonstrated protein arginine methyltransferase 1 (PRMT1) is upregulated in hepatocellular carcinoma (HCC) to methylate and activate phosphoglycerate dehydrogenase (PHGDH), thereby promoting serine synthesis. However, the mechanisms underlying PRMT1 upregulation and regulation of PRMT1-PHGDH axis remain unclear. Here, we show the E3 ubiquitin ligase F-box-only protein 7 (FBXO7) inhibits serine synthesis in HCC by binding PRMT1, inducing lysine 37 ubiquitination, and promoting proteosomal degradation of PRMT1. FBXO7-mediated PRMT1 downregulation cripples PHGDH arginine methylation and activation, resulting in impaired serine synthesis, accumulation of reactive oxygen species (ROS), and inhibition of HCC cell growth. Notably, FBXO7 is significantly downregulated in human HCC tissues, and inversely associated with PRMT1 protein and PHGDH methylation level. Overall, our study provides mechanistic insights into the regulation of cancer serine synthesis by FBXO7-PRMT1-PHGDH axis, and will facilitate the development of serine-targeting strategies for cancer therapy.

A comprehensive analysis and experimental validation of TK1 in uterine corpus endometrial carcinoma

Uterine corpus endometrial carcinoma (UCEC) is becoming a main malignant cancer that threaten to women's health. Thymidine kinase 1 (TK1) is considering to be associated with tumorigenesis and development. Nevertheless, the function of TK1 in UCEC is still unclear. Herein, we analyzed the TK1 expression level in pan-cancer and found that TK1 was upregulated in a variety of cancers including UCEC. Patients of UCEC with high expression of TK1 were related to poor outcome. TK1 was also related to clinical stage, histologic grade and lymph node metastasis. Abnormal expression of TK1 in UCEC was related to promoter methylation while gene mutation was not frequent. TK1 and its associated genes appeared to be prominent in cell cycle and DNA replication, according to GO and KEGG analysis. Analysis of immune infiltration revealed a negative correlation between TK1 and CD8 + T cells, macrophages, and dendritic cells. In vitro experiments, TK1 knockdown resulted in the inhibition of proliferation, migration, invasion and EMT in UCEC cell lines.

PRMT1-mediated PGK1 arginine methylation promotes colorectal cancer glycolysis and tumorigenesis

Many types of cancer cells, including colorectal cancer cells (CRC), can simultaneously enhance glycolysis and repress the mitochondrial tricarboxylic acid (TCA) cycle, which is called the Warburg effect. However, the detailed mechanisms of abnormal activation of the glycolysis pathway in colorectal cancer are largely unknown. In this study, we reveal that the protein arginine methyltransferase 1 (PRMT1) promotes glycolysis, proliferation, and tumorigenesis in CRC cells. Mechanistically, PRMT1-mediated arginine asymmetric dimethylation modification of phosphoglycerate kinase 1 (PGK1, the first ATP-producing enzyme in glycolysis) at R206 (meR206-PGK1) enhances the phosphorylation level of PGK1 at S203 (pS203-PGK1), which inhibits mitochondrial function and promotes glycolysis. We found that PRMT1 and meR206-PGK1 expression were positively correlated with pS203-PGK1 expression in tissues from colorectal cancer patients. Furthermore, we also confirmed that meR206-PGK1 expression is positively correlated with the poor survival of patients with colorectal cancer. Our findings show that PRMT1 and meR206-PGK1 may become promising predictive biomarkers for the prognosis of patients with CRC and that arginine methyltransferase inhibitors have great potential in colorectal cancer treatment.

Deciphering roles of TRIMs as promising targets in hepatocellular carcinoma: current advances and future directions

Tripartite motif (TRIM) family is assigned to RING-finger-containing ligases harboring the largest number of proteins in E3 ubiquitin ligating enzymes. E3 ubiquitin ligases target the specific substrate for proteasomal degradation via the ubiquitin-proteasome system (UPS), which seems to be a more effective and direct strategy for tumor therapy. Recent advances have demonstrated that TRIM genes associate with the occurrence and progression of hepatocellular carcinoma (HCC). TRIMs trigger or inhibit multiple biological activities like proliferation, apoptosis, metastasis, ferroptosis and autophagy in HCC dependent on its highly conserved yet diverse structures. Remarkably, autophagy is another proteolytic pathway for intracellular protein degradation and TRIM proteins may help to delineate the interaction between the two proteolytic systems. In depth research on the precise molecular mechanisms of TRIM family will allow for targeting TRIM in HCC treatment. We also highlight several potential directions warranted further development associated with TRIM family to provide bright insight into its translational values in hepatocellular carcinoma.