Non-canonical phosphoglycerate dehydrogenase activity promotes liver cancer growth via mitochondrial translation and respiratory metabolism.

Phosphoglycerate dehydrogenase (PHGDH) is a key serine biosynthesis enzyme whose aberrant expression promotes various types of tumors. Recently, PHGDH has been found to have some non-canonical functions beyond serine biosynthesis, but its specific mechanisms in tumorigenesis remain unclear. Here, we show that PHGDH localizes to the inner mitochondrial membrane and promotes the translation of mitochondrial DNA (mtDNA)-encoded proteins in liver cancer cells. Mechanistically, we demonstrate that mitochondrial PHGDH directly interacts with adenine nucleotide translocase 2 (ANT2) and then recruits mitochondrial elongation factor G2 (mtEFG2) to promote mitochondrial ribosome recycling efficiency, thereby promoting mtDNA-encoded protein expression and subsequent mitochondrial respiration. Moreover, we show that treatment with a mitochondrial translation inhibitor or depletion of mtEFG2 diminishes PHGDH-mediated tumor growth. Collectively, our findings uncover a previously unappreciated function of PHGDH in tumorigenesis acting via promotion of mitochondrial translation and bioenergetics.

A TGF-ß-dominant chemoresistant phenotype of hepatoblastoma associated with aflatoxin exposure in children.

BACKGROUND AND AIMS: Hepatoblastoma (HB) is the most common liver cancer in children, posing a serious threat to children's health. Chemoresistance is the leading cause of mortality in patients with HB. A more explicit definition of the features of chemotherapy resistance in HB represents a fundamental urgent need. APPROACH AND RESULTS: We performed an integrative analysis including single-cell RNA sequencing, whole-exome sequencing, and bulk RNA sequencing in 180 HB samples, to reveal genomic features, transcriptomic profiles, and the immune microenvironment of HB. Multicolor immunohistochemistry staining and in vitro experiments were performed for validation. Here, we reported four HB transcriptional subtypes primarily defined by differential expression of transcription factors. Among them, the S2A subtype, characterized by strong expression of progenitor ( MYCN , MIXL1 ) and mesenchymal transcription factors ( TWIST1 , TBX5 ), was defined as a new chemoresistant subtype. The S2A subtype showed increased TGF-ß cancer-associated fibroblast and an immunosuppressive microenvironment induced by the upregulated TGF-ß of HB. Interestingly, the S2A subtype enriched SBS24 signature and significantly higher serum aflatoxin B1-albumin (AFB1-ALB) level in comparison with other subtypes. Functional assays indicated that aflatoxin promotes HB to upregulate TGF-ß. Furthermore, clinical prognostic analysis showed that serum AFB1-ALB is a potential indicator of HB chemoresistance and prognosis. CONCLUSIONS: Our studies offer new insights into the relationship between aflatoxin and HB chemoresistance and provide important implications for its diagnosis and treatment.

PGAM5 deacetylation mediated by SIRT2 facilitates lipid metabolism and liver cancer proliferation.

Tumor metabolic reprogramming and epigenetic modification work together to promote tumorigenesis and development. Protein lysine acetylation, which affects a variety of biological functions of proteins, plays an important role under physiological and pathological conditions. Here, through immunoprecipitation and mass spectrum data, we show that phosphoglycerate mutase 5 (PGAM5) deacetylation enhances malic enzyme 1 (ME1) metabolic enzyme activity to promote lipid synthesis and proliferation of liver cancer cells. Mechanistically, we demonstrate that the deacetylase SIRT2 mediates PGAM5 deacetylation to activate ME1 activity, leading to ME1 dephosphorylation, subsequent lipid accumulation and the proliferation of liver cancer cells. Taken together, our study establishes an important role for the SIRT2-PGAM5-ME1 axis in the proliferation of liver cancer cells, suggesting a potential innovative cancer therapy.

Structural insights into the specific recognition of mitochondrial ribosome-binding factor hsRBFA and 12 S rRNA by methyltransferase METTL15.

Mitochondrial rRNA modifications are essential for mitoribosome assembly and its proper function. The m4C methyltransferase METTL15 maintains mitochondrial homeostasis by catalyzing m4C839 located in 12 S rRNA helix 44 (h44). This modification is essential to fine-tuning the ribosomal decoding center and increasing decoding fidelity according to studies of a conserved site in Escherichia coli. Here, we reported a series of crystal structures of human METTL15-hsRBFA-h44-SAM analog, METTL15-hsRBFA-SAM, METTL15-SAM and apo METTL15. The structures presented specific interactions of METTL15 with different substrates and revealed that hsRBFA recruits METTL15 to mitochondrial small subunit for further modification instead of 12 S rRNA. Finally, we found that METTL15 deficiency caused increased reactive oxygen species, decreased membrane potential and altered cellular metabolic state. Knocking down METTL15 caused an elevated lactate secretion and increased levels of histone H4K12-lactylation and H3K9-lactylation. METTL15 might be a suitable model to study the regulation between mitochondrial metabolism and histone lactylation.

Th17 Cells Secrete TWEAK to Trigger Epithelial-Mesenchymal Transition and Promote Colorectal Cancer Liver Metastasis.

Liver metastasis is the leading cause of mortality in patients with colorectal cancer. Given the significance of both epithelial-mesenchymal transition (EMT) of tumor cells and the immune microenvironment in colorectal cancer liver metastasis (CRLM), the interplay between them could hold the key for developing improved treatment options. We employed multiomics analysis of 130 samples from 18 patients with synchronous CRLM integrated with external datasets to comprehensively evaluate the interaction between immune cells and EMT of tumor cells in liver metastasis. Single-cell RNA sequencing analysis revealed distinct distributions of nonmalignant cells between primary tumors from patients with metastatic colorectal cancer (mCRC) and non-metastatic colorectal cancer, showing that Th17 cells were predominantly enriched in the primary lesion of mCRC. TWEAK, a cytokine secreted by Th17 cells, promoted EMT by binding to receptor Fn14 on tumor cells, and the TWEAK-Fn14 interaction enhanced tumor migration and invasion. In mouse models, targeting Fn14 using CRISPR-induced knockout or lipid nanoparticle-encapsulated siRNA alleviated metastasis and prolonged survival. Mice lacking Il17a or Tnfsf12 (encoding TWEAK) exhibited fewer metastases compared with wild-type mice, while cotransfer of Th17 with tumor cells promoted liver metastasis. Higher TWEAK expression was associated with a worse prognosis in patients with colorectal cancer. In addition, CD163L1+ macrophages interacted with Th17 cells, recruiting Th17 via the CCL4-CCR5 axis. Collectively, this study unveils the role of immune cells in the EMT process and identifies TWEAK secreted by Th17 as a driver of CRLM. SIGNIFICANCE: TWEAK secreted by Th17 cells promotes EMT by binding to Fn14 on colorectal cancer cells, suggesting that blocking the TWEAK-Fn14 interaction may be a promising therapeutic approach to inhibit liver metastasis.

Biodegradable CuMoO4 Nanodots with Multienzyme Activities for Multimodal Treatment of Tumor.

Due to their complexity and variability, tumors need to be treated with multimodal combined therapy, which requires the development of therapeutic agents that can provide multimodal therapeutic effects. Herein, CuMoO4 nanodots smaller than 10 nm that can be prepared by simple hydrothermal method are reported. These nanodots can be well dispersed in water and have good biosafety and biodegradability. Further studies show that these nanodots also present multienzyme activities, such as catalase, peroxidase and glutathione peroxidase. In addition, CuMoO4 nanodots exhibit high photothermal conversion efficiency (41%) under 1064 nm near-infrared laser irradiation. In vitro and in vivo experimental results indicate that CuMoO4 nanodots can effectively inhibit the instinctive regulation of tumor cells to oxidative stress, provide sustained treatment to achieve photothermal synergistic ferroptosis, and trigger immune responses to immunogenic cell death. It is worth mentioning that the CuMoO4 nanodots also cause cuproptosis of tumor cells. This study provides a promising nanoplatform for multimodal combined therapy of cancer.

Synergistic therapeutic effect of nanomotors triggered by Near-infrared light and acidic conditions of tumor.

Due to the complexity of tumors, multimodal therapy for them has always been of concern to researchers. How to design a multifunctional drug nanoplatform with cascade effect and capable of responding to specific stimuli in the tumor microenvironment is the key to achieve efficient multimodal synergistic therapy of cancer. Here, we prepare a kind of GNRs@SiO2@PDA-CuO2-l-Arg (GSPRs-CL) nanomotors for systematic treatment of tumor. First, under near-infrared (NIR) irradiation, GSPRs-CL can generate heat and exhibit excellent photothermal therapy effect. Then under acidic conditions, CuO2 can be decomposed to release Cu2+ and generate H2O2, which not only complemented the limited endogenous H2O2 in cells, but also further triggered Fenton-like reaction, converting H2O2 into •OH to kill cancer cells, thereby achieving chemodynamic therapy. Furthermore, both endogenous and exogenous H2O2 can release nitric oxide (NO) in response to the occurrence of l-Arg of nanomotors to enhance gas therapy. In addition, as a dual-mode drive, NIR laser and NO can promote the penetration ability of nanomotors at tumor sites. The experimental results in vivo show that the drug nanoplatform had good biosafety and significant tumor killing effect triggered by NIR light and acidic conditions of tumor. It provide a promising strategy for the development of advanced drug nanoplatform for cancer therapy.

Polydopamine nanomotors loaded indocyanine green and ferric ion for photothermal and photodynamic synergistic therapy of tumor.

The limited penetration depth of nanodrugs in the tumor and the severe hypoxia inside the tumor significantly reduce the efficacy of photothermal-photodynamic synergistic therapy (PTT-PDT). Here, we synthesized a methoxypolyethylene glycol amine (mPEG-NH2)-modified walnut-shaped polydopamine nanomotor (PDA-PEG) driven by near-infrared light (NIR). At the same time, it also loaded the photosensitizer indocyanine green (ICG) via electrostatic/hydrophobicinteractions and chelated with ferric ion (Fe3+). Under the irradiation of NIR, the asymmetry of PDA-PEG morphology led to the asymmetry of local photothermal effects and the formation of thermal gradient, which can make the nanomotor move autonomously. This ability of autonomous movement was proved to be used to improve the permeability of the nanomotor in three-dimensional (3D) tumor sphere. Fe3+ can catalyze endogenous hydrogen peroxide to produce oxygen, so as to overcome the hypoxia of tumor microenvironment and thereby generate more singlet oxygen to kill tumor cells. Animal experiments in vivo confirmed that the nanomotors had a good PTT-PDT synergistic treatment effect. The introduction of nanomotor technology has brought new ideas for cancer optical therapy.

Highly Penetrable Drug-Loaded Nanomotors for Photothermal-Enhanced Ferroptosis Treatment of Tumor.

A kind of drug-loaded nanomotors with deep penetration was developed to improve the therapeutic effect of ferroptosis on tumor. The nanomotors were constructed by co-loading hemin and ferrocene (Fc) on the surface of bowl-shaped polydopamine (PDA) nanoparticles. The near-infrared response of PDA makes the nanomotor have high tumor penetration capability. In vitro experiments show that the nanomotors can exhibit good biocompatibility, high light to heat conversion efficiency, and deep tumor permeability. It is worth noting that under the catalysis of H2O2 overexpressed in the tumor microenvironment, the Fenton-like reagents hemin and Fc loaded on the nanomotors can increase the concentration of toxic •OH. Furthermore, hemin can consume glutathione in tumor cells and trigger the up-regulation of heme oxygenase-1, which can efficiently decompose hemin to Fe2+, thus producing the Fenton reaction and causing a ferroptosis effect. Notably, thanks to the photothermal effect of PDA, it can enhance the generation of reactive oxygen species and thus intervene in the Fenton reaction process, thereby enhancing the ferroptosis effect photothermally. In vivo antitumor results show that the drug-loaded nanomotors with high penetrability showed an effective antitumor therapeutic effect.

Construction of a matchstick-shaped Au@ZnO@SiO2-ICG Janus nanomotor for light-triggered synergistic antibacterial therapy.

The drug-resistance of bacteria poses a serious threat to public health, so the exploration of new antibacterial materials has attracted extensive attention. Here, we report Au@ZnO@SiO2-ICG nanomotors as an antibacterial candidate. Firstly, we prepared the Janus structure Au@ZnO loaded with indocyanine green (ICG) and constructed a synergistic antibacterial platform with photothermal and photodynamic properties triggered by dual light sources. Specifically, the metal/semiconductor heterostructure of Au@ZnO has a synergistic effect under ultraviolet (UV) irradiation, which can adjust the transfer of interface electrons, so as to greatly improve the generation of cytotoxic ROS for photodynamic sterilization. The loaded ICG is an effective photosensitizer, and can induce a stronger photothermal effect in collaboration with Au under near-infrared light (NIR). In addition, the asymmetric structures of nanomotors have autonomous movement with the help of generated temperature gradient when exposed to NIR light, conducive to breaking through the bacterial membrane and improving the membrane insertion ability of antibacterial therapeutic agents. The results indicate that the prepared Au@ZnO@SiO2-ICG nanomotors show excellent light responses and synergistic sterilization ability to Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). This study will provide a new idea for the application of metal-semiconductor nanocomposites in the treatment of bacterial infection.

Identification of DNA methylation signatures for hepatocellular carcinoma detection and microvascular invasion prediction.

BACKGROUND AND AIM: Preoperative evaluation of microvascular invasion (MVI) in patients with hepatocellular carcinoma (HCC) is important for surgical strategy determination. We aimed to develop and establish a preoperative predictive model for MVI status based on DNA methylation markers. METHODS: A total of 35 HCC tissues and the matched peritumoral normal liver tissues as well as 35 corresponding HCC patients' plasma samples and 24 healthy plasma samples were used for genome-wide methylation sequencing and subsequent methylation haplotype block (MHB) analysis. Predictive models were constructed based on selected MHB markers and 3-cross validation was used. RESULTS: We grouped 35 HCC patients into 2 categories, including the MVI- group with 17 tissue and plasma samples, and MVI + group with 18 tissue and plasma samples. We identified a tissue DNA methylation signature with an AUC of 98.0% and a circulating free DNA (cfDNA) methylation signature with an AUC of 96.0% for HCC detection. Furthermore, we established a tissue DNA methylation signature for MVI status prediction, and achieved an AUC of 85.9%. Based on the MVI status predicted by the DNA methylation signature, the recurrence-free survival (RFS) and overall survival (OS) were significantly better in the predicted MVI- group than that in the predicted MVI + group. CONCLUSIONS: In this study, we identified a cfDNA methylation signature for HCC detection and a tissue DNA methylation signature for MVI status prediction with high accuracy.

ENO1 suppresses cancer cell ferroptosis by degrading the mRNA of iron regulatory protein 1.

α-Enolase 1 (ENO1) is a critical glycolytic enzyme whose aberrant expression drives the pathogenesis of various cancers. ENO1 has been indicated as having additional roles beyond its conventional metabolic activity, but the underlying mechanisms and biological consequences remain elusive. Here, we show that ENO1 suppresses iron regulatory protein 1 (IRP1) expression to regulate iron homeostasis and survival of hepatocellular carcinoma (HCC) cells. Mechanistically, we demonstrate that ENO1, as an RNA-binding protein, recruits CNOT6 to accelerate the messenger RNA decay of IRP1 in cancer cells, leading to inhibition of mitoferrin-1 (Mfrn1) expression and subsequent repression of mitochondrial iron-induced ferroptosis. Moreover, through in vitro and in vivo experiments and clinical sample analysis, we identified IRP1 and Mfrn1 as tumor suppressors by inducing ferroptosis in HCC cells. Taken together, this study establishes an important role for the ENO1-IRP1-Mfrn1 pathway in the pathogenesis of HCC and reveals a previously unknown connection between this pathway and ferroptosis, suggesting a potential innovative cancer therapy.

Hypoxia-Induced Suppression of Alternative Splicing of MBD2 Promotes Breast Cancer Metastasis via Activation of FZD1.

Metastasis is responsible for the majority of breast cancer-related deaths, however, the mechanisms underlying metastasis in this disease remain largely elusive. Here we report that under hypoxic conditions, alternative splicing of MBD2 is suppressed, favoring the production of MBD2a, which facilitates breast cancer metastasis. Specifically, MBD2a promoted, whereas its lesser known short form MBD2c suppressed metastasis. Activation of HIF1 under hypoxia facilitated MBD2a production via repression of SRSF2-mediated alternative splicing. As a result, elevated MBD2a outcompeted MBD2c for binding to promoter CpG islands to activate expression of FZD1, thereby promoting epithelial-to-mesenchymal transition and metastasis. Strikingly, clinical data reveal significantly correlated expression of MBD2a and MBD2c with the invasiveness of malignancy, indicating opposing roles for MBD2 splicing variants in regulating human breast cancer metastasis. Collectively, our findings establish a novel link between MBD2 switching and tumor metastasis and provide a promising therapeutic strategy and predictive biomarkers for hypoxia-driven breast cancer metastasis. SIGNIFICANCE: This study defines the opposing roles and clinical relevance of MBD2a and MBD2c, two MBD2 alternative splicing products, in hypoxia-driven breast cancer metastasis. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/5/1265/F1.large.jpg.

Prognostic value of glucose transporter 3 expression in hepatocellular carcinoma.

Determining an effective biomarker for predicting the prognosis of patients with hepatocellular carcinoma (HCC) may improve patient survival rates. The present study aimed to investigate the expression of glucose transporter 3 (GLUT-3) in HCC and to determine its predictive value for the survival of patients with HCC. Immunohistochemistry was used to detect GLUT-3 expression in HCC tissues of 275 and 140 patients with HCC from training and validation cohorts, respectively. The association between GLUT-3 expression and the clinicopathological characteristics of patients with HCC, and between GLUT-3 expression and patient survival rates were analyzed. The predictive value of GLUT-3 expression was confirmed using the validation cohort. The results demonstrated that the high GLUT-3 expression in HCC tissues was significantly associated with elevated α-fetoprotein level, large tumor size, poor histological differentiation and Tumor-Node-Metastasis stages III and IV (P<0.05). In addition, GLUT-3 high expression was also significantly associated with reduced overall survival of patients with HCC in the training and validation cohorts. In conclusion, the results from the present study suggested that GLUT-3 may be considered as a potential independent prognostic factor for predicting the survival of patients with HCC.

Myc-mediated SDHA acetylation triggers epigenetic regulation of gene expression and tumorigenesis.

The transcriptional role of cMyc (or Myc) in tumorigenesis is well appreciated; however, it remains to be fully established how extensively Myc is involved in the epigenetic regulation of gene expression. Here, we show that by deactivating succinate dehydrogenase complex subunit A (SDHA) via acetylation, Myc triggers a regulatory cascade in cancer cells that leads to H3K4me3 activation and gene expression. We find that Myc facilitates the acetylation-dependent deactivation of SDHA by activating the SKP2-mediated degradation of SIRT3 deacetylase. We further demonstrate that Myc inhibition of SDH-complex activity leads to cellular succinate accumulation, which triggers H3K4me3 activation and tumour-specific gene expression. We demonstrate that acetylated SDHA at Lys 335 contributes to tumour growth in vitro and in vivo, and we confirm increased tumorigenesis in clinical samples. This study illustrates a link between acetylation-dependent SDHA deactivation and Myc-driven epigenetic regulation of gene expression, which is critical for cancer progression.