Elucidating the genotoxicity of Fusobacterium nucleatum-secreted mutagens in colorectal cancer carcinogenesis.

BACKGROUND: Fusobacterium nucleatum (F. nucleatum) is one of the key tumorigenic bacteria in colorectal cancer (CRC), yet how F. nucleatum is involved in colorectal cancer carcinogenesis remains unknown. RESULTS: In the present study, we carried out PathSeq analysis on RNA sequencing data from the 430 primary colon adenocarcinomas in TCGA database to assess the relationship between patients' survival and F. nucleatum abundance. Among patients with cecum and ascending colon tumors, we found that F. nucleatum transcriptome abundance is positively correlated with mutation load. We further demonstrated that patients with both high tumoral abundance of F. nucleatum and high mutation load exhibited poorer survival and DNA damage. We furthermore determined that F. nucleatum-conditioned medium (Fn. CM) induces DNA damage in both in vitro and in vivo studies. In addition, two F. nucleatum-secreted mutagens, namely DL-homocystine and allantoic acid, were identified to lead to DNA damage. CONCLUSIONS: Our finding delineates the genotoxicity of F.nucleatum-secreted mutagens, which provides a basis for further work to investigate the role of F. nucleatum in the pathogenicity of CRC.

Increased Expression of PDGFA Is Associated With Poor Prognosis and Immune Infiltration in Head and Neck Squamous Cell Carcinoma.

BACKGROUND: Platelet-derived growth factor A (PDGFA) has been shown to be upregulated in several tumors, contributing to their malignant phenotypes. However, its expression and function in head and neck squamous cell carcinoma (HNSC) are not clearly understood. Thus, we aimed to evaluate this issue using bioinformatic analyses and primary experimental validation. METHODS: The expression of PDGFA was analyzed using popular bio-databases and further validated by RT-PCR and immunohistochemical staining. Survival analyses were then performed. The association between PDGFA expression levels and immune cell infiltration in the immune microenvironment was assessed. RESULTS: PDGFA has been found to be significantly upregulated in a variety of cancers, including HNSC, and increased PDGFA expression may be an independent prognostic factor associated with immune cell infiltration in HNSC. CONCLUSION: Overexpression of PDGFA in HNSC is significantly associated with poor prognosis and immune cell infiltration in the tumor microenvironment (TME). PDGFA has potential as a molecular indicator for diagnosis, prognosis, and immune processes in HNSC.

Evaluating the Effect of Telomere Length on Oral and Oropharyngeal Cancer Risk Using Mendelian Randomization.

INTRODUCTION: The aim of this study was to explore the causal relationship between telomere length and Oral and oropharyngeal cancers by using Mendelian randomization (MR) analysis. METHODS: We carried out a 2-sample MR to examine the causal association between telomere length and Oral and oropharyngeal cancers. Two large genome-wide association studies (GWAS) were employed to identify single nucleotide polymorphisms (SNPs) as instrumental variables through statistical and biological approaches. The data on SNP-oral and oropharyngeal cancer risk factor associations were sourced from various consortia/UK Biobank. The inverse variance weighted (IVW) method was employed as the primary approach for overall causal estimation in MR, with sensitivity analyses conducted to assess potential confounding by pleiotropy, heterogeneity, and the leave-one-out analysis. RESULTS: The statistically driven approach indicates limited evidence of a genetically causal effect of telomere length on the risk of oral cavity cancer (OR = 0.999, 95% CI 0.998-1.000, P = .100), oropharyngeal cancer (OR = 0.999, 95% CI 0.998-1.001, P = .650), combined oral and oropharyngeal cancer (OR = 0.999, 95% CI 0.998-1.000, P = .119) in Europeans. The biologically driven approach demonstrated consistent causal effects across all MR methods, thereby further strengthening the reliability of the results. Moreover, the MR-Egger (Q [df] 170.816 [130], P = .009) and inverse variance weighted methods (Q [df] 171.656 [131], P = .010) identified considerable heterogeneity among instrumental variable estimates in Oral cavity cancer, and no evidence of horizontal pleiotropy was detected. CONCLUSIONS: No significant causal associations between telomere length and Oral and oropharyngeal cancers were found in this study.

[Corrigendum] Cancer­associated fibroblasts from invasive breast cancer have an attenuated capacity to secrete collagens.

Subsequently to the publication of the above article, an interested reader drew to the authors' attention that the GAPDH bands shown for the western blots portrayed in Fig. 2 (associated with the α­SMA proteins) on p. 1482 were strikingly similar to the GAPDH bands associated with the CAF64 and NF64 experiments in Fig. 4 on p. 1485. After re­examining their original data, the authors have realized that the GAPDH protein bands correctly shown in Fig. 4 had inadvertently been included in Fig. 2. The revised version of Fig. 2, showing the GAPDH bands that were correctly associated with the α­SMA proteins, is shown opposite. The authors are grateful to the Editor of International Journal of Oncology for allowing them this opportunity to publish a Corrigendum, and all the authors agree to its publication. Note that this error did not grossly affect either the results or the conclusions reported in this study; furthermore, the authors apologize to the readership for any inconvenience caused. [International Journal of Oncology 45: 1479­1488, 2014; DOI: 10.3892/ijo.2014.2562].

Biomechanical analysis of the tandem spinal external fixation in a multiple-level noncontiguous lumbar fractures model: a finite element analysis.

Objective: This study aimed to investigate the biomechanical characteristics of the tandem spinal external fixation (TSEF) for treating multilevel noncontiguous spinal fracture (MNSF) using finite element analysis and provide a theoretical basis for clinical application. Methods: We constructed two models of L2 and L4 vertebral fractures that were fixed with the TSEF and the long-segment spinal inner fixation (LSIF). The range of motion (ROM), maximum stresses at L2 and L4 vertebrae, the screws and rods, and the intervertebral discs of the two models were recorded under load control. Subsequently, the required torque, the maximum stress at L2 and L4 vertebrae, the screws and rods, and the intervertebral discs were analyzed under displacement control. Results: Under load control, the TSEF model reserved more ROM than the LSIF model. The maximum stresses of screws in the TSEF model were increased, while the maximum stresses of rods were reduced compared to the LSIF model. Moreover, the maximum stresses of L2 and L4 vertebrae and discs in the TSEF model were increased compared to the LSIF model. Under displacement control, the TSEF model required fewer moments (N·mm) than the LSIF model. Compared to the LSIF model, the maximum stresses of screws and rods in the TSEF model have decreased; the maximum stresses at L2 and L4 in the TSEF model were increased. In the flexion condition, the maximum stresses of discs in the TSEF model were less than the LSIF model, while the maximum stresses of discs in the TSEF model were higher in the extension condition. Conclusion: Compared to LSIF, the TSEF has a better stress distribution with higher overall mobility. Theoretically, it reduces the stress concentration of the connecting rods and the stress shielding of the fractured vertebral bodies.

Construction and assessment of an angiogenesis-related gene signature for prognosis of head and neck squamous cell carcinoma.

OBJECTIVE: Angiogenesis-associated genes (AAGs) play a critical role in cancer patient survival. However, there are insufficient reports on the prognostic value of AAGs in head and neck squamous cell carcinoma (HNSC). Therefore, this study aimed to investigate the correlation between AAG expression levels and survival in HNSC patients, explore the predictive value of signature genes and lay the groundwork for future in-depth research. METHODS: Relevant data for HNSC were obtained from the databases. AAGs-associated signature genes linked to prognosis were screened to construct a predictive model. Further analysis was conducted to determine the functional correlation of the signature genes. RESULTS: The signature genes (STC1, SERPINA5, APP, OLR1, and PDGFA) were used to construct prognostic models. Patients were divided into high-risk and low-risk groups based on the calculated risk scores. Survival analysis showed that patients in the high-risk group had a significantly lower overall survival than those in the low-risk group (P < 0.05). Therefore, this prognostic model was an independent prognostic factor for predicting HNSC. In addition, patients in the low-risk group were more sensitive to multiple anti-cancer drugs. Functional correlation analysis showed a good correlation between the characteristic genes and HNSC metastasis, invasion, and angiogenesis. CONCLUSION: This study established a new prognostic model for AAGs and may guide the selection of therapeutic agents for HNSC. These genes have important functions in the tumor microenvironment; it also provides a valuable resource for the future clinical trials investigating the relationship between HNSC and AAGs.

FOXP4 is a Direct YAP1 Target that Promotes Gastric Cancer Stemness and Drives Metastasis.

The Hippo-YAP1 pathway is an evolutionally conserved signaling cascade that controls organ size and tissue regeneration. Dysregulation of Hippo-YAP1 signaling promotes initiation and progression of several types of cancer, including gastric cancer (GC). As the Hippo-YAP1 pathway regulates expression of thousands of genes, it is important to establish which target genes contribute to the oncogenic program driven by YAP1 to identify strategies to circumvent it. Here, we identified a vital role of FOXP4 in YAP1-driven gastric carcinogenesis by maintaining stemness and promoting peritoneal metastasis. Loss of FOXP4 impaired GC spheroid formation and reduced stemness marker expression, while FOXP4 upregulation potentiated cancer cell stemness. RNA-seq analysis revealed SOX12 as downstream target of FOXP4, and functional studies established that SOX12 supports stemness in YAP1-induced carcinogenesis. A small molecule screen identified 42-(2-Tetrazolyl)rapamycin as a FOXP4 inhibitor, and targeting FOXP4 suppressed GC tumor growth and enhanced the efficacy of 5-FU chemotherapy in vivo. Collectively, these findings revealed that FOXP4 upregulation by YAP1 in GC regulates stemness and tumorigenesis by upregulating SOX12. Targeting the YAP1-FOXP4-SOX12 axis represents a potential therapeutic strategy for GC.

RUVBL1/2 Blockade Targets YTHDF1 Activity to Suppress m6A-Dependent Oncogenic Translation and Colorectal Tumorigenesis.

The N6-methyladenosine (m6A) RNA-binding protein YTHDF1 is frequently overexpressed in colorectal cancer and drives chemotherapeutic resistance. To systematically identify druggable targets in colorectal cancer with high expression of YTHDF1, this study used a CRISPR/Cas9 screening strategy that revealed RUVBL1 and RUVBL2 as putative targets. RUVBL1/2 were overexpressed in primary colorectal cancer samples and represented independent predictors of poor patient prognosis. Functionally, loss of RUVBL1/2 preferentially impaired the growth of YTHDF1-high colorectal cancer cells, patient-derived primary colorectal cancer organoids, and subcutaneous xenografts. Mechanistically, YTHFD1 and RUVBL1/2 formed a positive feedforward circuit to accelerate oncogenic translation. YTHDF1 bound to m6A-modified RUVBL1/2 mRNA to promote translation initiation and protein expression. Coimmunoprecipitation and mass spectrometry identified that RUVBL1/2 reciprocally interacted with YTHDF1 at 40S translation initiation complexes. Consequently, RUVBL1/2 depletion stalled YTHDF1-driven oncogenic translation and nascent protein biosynthesis, leading to proliferative arrest and apoptosis. Ribosome sequencing revealed that RUVBL1/2 loss impaired the activation of MAPK, RAS, and PI3K-AKT signaling induced by YTHDF1. Finally, the blockade of RUVBL1/2 by the pharmacological inhibitor CB6644 or vesicle-like nanoparticle-encapsulated siRNAs preferentially arrested the growth of YTHDF1-expressing colorectal cancer in vitro and in vivo. Our findings show that RUVBL1/2 are potential prognostic markers and druggable targets that regulate protein translation in YTHDF1-high colorectal cancer. Significance: RUVBL1/2 inhibition is a therapeutic strategy to abrogate YTHDF1-driven oncogenic translation and overcome m6A dysregulation in colorectal cancer.

Immunohistochemical Expression and Clinical Significance of WWP1 Protein in Nasopharyngeal Cancer.

Nasopharyngeal carcinoma (NPC) is a common malignant tumor of the head and neck. Its pathogenesis is complicated and needs further investigation. The aim of this study was to investigate the expression and clinical significance of WWP1 in NPC. Bioinformatics approaches were used to evaluate the expression and functions of WWP1 in NPC. WWP1 protein expression was then detected by immunohistochemistry on a tissue microarray in an NPC cohort and its association with clinical features and prognosis was determined. In addition, WWP1 expression was knocked down in NPC cells using RNA interference, and their colony formation and invasion abilities were assessed. A total of 25 genes closely related to WWP1, which may be enriched in different pathways, were filtered out. WWP1 expression was significantly higher in NPC cells than in normal controls. High WWP1 expression was correlated with lymph node metastasis, tumor recurrence, clinical stage and poor prognosis. Knockdown of WWP1 resulted in attenuated proliferation and invasion of NPC cells. The results suggest that WWP1 may serve as a novel biomarker and prognostic factor for NPC and a potential therapeutic target worthy of further investigation.

Blood microbial signatures associated with mortality in patients with sepsis: A pilot study.

Sepsis is a life-threatening illness caused by the dysregulated host response to infection. Nevertheless, our current knowledge of the microbial landscape in the blood of septic patients is still limited. Next-generation sequencing (NGS) is a sensitive method to quantitatively characterize microbiomes at various sites of the human body. In this study, we analyzed the blood microbial DNA of 22 adult patients with sepsis and 3 healthy subjects. The presence of non-human DNA was identified in both healthy and septic subjects. Septic patients had a markedly altered microbial DNA profile compared to healthy subjects over α- and ß-diversity. Unexpectedly, the patients could be further divided into two subgroups (C1 and C2) based on ß-diversity analysis. C1 patients showed much higher bacteria, viruses, fungi, and archaea abundance, and a higher level of α-diversity (Chao1, Observed and Shannon index) than both C2 patients and healthy subjects. The most striking difference was seen in the case of Streptomyces violaceusniger, Phenylobacterium sp. HYN0004, Caulobacter flavus, Streptomyces sp. 11-1-2, and Phenylobacterium zucineum, the abundance of which was the highest in the C1 group. Notably, C1 patients had a significantly poorer outcome than C2 patients. Moreover, by analyzing the patterns of microbe-microbe interactions in healthy and septic subjects, we revealed that C1 and C2 patients exhibited distinct co-occurrence and co-exclusion relationships. Together, our study uncovered two distinct microbial signatures in the blood of septic patients. Compositional and ecological analysis of blood microbial DNA may thus be useful in predicting mortality of septic patients.

A winged relative of ice-crawlers in amber bridges the cryptic extant Xenonomia and a rich fossil record.

Until the advent of phylogenomics, the atypical morphology of extant representatives of the insect orders Grylloblattodea (ice-crawlers) and Mantophasmatodea (gladiators) had confounding effects on efforts to resolve their placement within Polyneoptera. This recent research has unequivocally shown that these species-poor groups are closely related and form the clade Xenonomia. Nonetheless, divergence dates of these groups remain poorly constrained, and their evolutionary history debated, as the few well-identified fossils, characterized by a suite of morphological features similar to that of extant forms, are comparatively young. Notably, the extant forms of both groups are wingless, whereas most of the pre-Cretaceous insect fossil record is composed of winged insects, which represents a major shortcoming of the taxonomy. Here, we present new specimens embedded in mid-Cretaceous amber from Myanmar and belonging to the recently described species Aristovia daniili. The abundant material and pristine preservation allowed a detailed documentation of the morphology of the species, including critical head features. Combined with a morphological data set encompassing all Polyneoptera, these new data unequivocally demonstrate that A. daniili is a winged stem Grylloblattodea. This discovery demonstrates that winglessness was acquired independently in Grylloblattodea and Mantophasmatodea. Concurrently, wing apomorphic traits shared by the new fossil and earlier fossils demonstrate that a large subset of the former "Protorthoptera" assemblage, representing a third of all known insect species in some Permian localities, are genuine representatives of Xenonomia. Data from the fossil record depict a distinctive evolutionary trajectory, with the group being both highly diverse and abundant during the Permian but experiencing a severe decline from the Triassic onwards.

LOX-1 acts as an N6-methyladenosine-regulated receptor for Helicobacter pylori by binding to the bacterial catalase.

The role of N6-methyladenosine (m6A) modification of host mRNA during bacterial infection is unclear. Here, we show that Helicobacter pylori infection upregulates host m6A methylases and increases m6A levels in gastric epithelial cells. Reducing m6A methylase activity via hemizygotic deletion of methylase-encoding gene Mettl3 in mice, or via small interfering RNAs targeting m6A methylases, enhances H. pylori colonization. We identify LOX-1 mRNA as a key m6A-regulated target during H. pylori infection. m6A modification destabilizes LOX-1 mRNA and reduces LOX-1 protein levels. LOX-1 acts as a membrane receptor for H. pylori catalase and contributes to bacterial adhesion. Pharmacological inhibition of LOX-1, or genetic ablation of Lox-1, reduces H. pylori colonization. Moreover, deletion of the bacterial catalase gene decreases adhesion of H. pylori to human gastric sections. Our results indicate that m6A modification of host LOX-1 mRNA contributes to protection against H. pylori infection by downregulating LOX-1 and thus reducing H. pylori adhesion.

High Soluble Fiber Promotes Colorectal Tumorigenesis Through Modulating Gut Microbiota and Metabolites in Mice.

BACKGROUND & AIMS: Dietary fibers are mainly fermented by the gut microbiota, but their roles in colorectal cancer (CRC) are largely unclear. Here, we investigated the associations of different fibers with colorectal tumorigenesis in mice. METHODS: Apcmin/+ mice and C57BL/6 mice with azoxymethane (AOM) injection were used as CRC mouse models. Mice were fed with mixed high-fiber diet (20% soluble fiber and 20% insoluble fiber), high-inulin diet, high-guar gum diet, high-cellulose diet, or diets with different inulin dose. Germ-free mice were used for validation. Fecal microbiota and metabolites were profiled by shotgun metagenomic sequencing and liquid chromatography-mass spectrometry, respectively. RESULTS: Mixed high-fiber diet promoted colorectal tumorigenesis with increased tumor number and tumor load in AOM-treated and Apcmin/+ mice. Antibiotics use abolished the pro-tumorigenic effect of mixed high-fiber diet, while transplanting stools from mice fed with mixed high-fiber diet accelerated tumor growth in AOM-treated germ-free mice. We therefore characterized the contribution of soluble and insoluble fiber in CRC separately. Our results revealed that soluble fiber inulin or guar gum, but not insoluble fiber cellulose, promoted colorectal tumorigenesis in AOM-treated and Apcmin/+ mice. Soluble fiber induced gut dysbiosis with Bacteroides uniformis enrichment and Bifidobacterium pseudolongum depletion, accompanied by increased fecal butyrate and serum bile acids and decreased inosine. We also identified a positive correlation between inulin dosage and colorectal tumorigenesis. Moreover, transplanting stools from mice fed with high-inulin diet increased colonic cell proliferation and oncogene expressions in germ-free mice. CONCLUSION: High-dose soluble but not insoluble fiber potentiates colorectal tumorigenesis in a dose-dependent manner by dysregulating gut microbiota and metabolites in mice.

Spatial proteomics of immune microenvironment in nonalcoholic steatohepatitis-associated hepatocellular carcinoma.

BACKGROUND AND AIMS: NASH-HCC is inherently resistant to immune checkpoint blockade, but its tumor immune microenvironment is largely unknown. APPROACH AND RESULTS: We applied the imaging mass cytometry to construct a spatially resolved single-cell atlas from the formalin-fixed and paraffin-embedded tissue sections from patients with NASH-HCC, virus-HCC (HBV-HCC and HCV-HCC), and healthy donors. Based on 35 biomarkers, over 750,000 individual cells were categorized into 13 distinct cell types, together with the expression of key immune functional markers. Higher infiltration of T cells, myeloid-derived suppressor cell (MDSCs), and tumor-associated macrophages (TAMs) in HCC compared to controls. The distribution of immune cells in NASH-HCC is spatially heterogeneous, enriched at adjacent normal tissues and declined toward tumors. Cell-cell connections analysis revealed the interplay of MDSCs and TAMs with CD8 + T cells in NASH-HCC. In particular, exhausted programmed cell death 1 (PD-1 + )CD8 + T cells connected with programmed cell death-ligand 1 (PD-L1 + )/inducible T cell costimulator (ICOS + ) MDSCs and TAMs in NASH-HCC, but not in viral HCC. In contrast, CD4 + /CD8 + T cells with granzyme B positivity were reduced in NASH-HCC. Tumor cells expressed low PD-L1 and showed few connections with immune cells. CONCLUSIONS: Our work provides the first detailed spatial map of single-cell phenotypes and multicellular connections in NASH-HCC. We demonstrate that interactions between MDSCs and TAMs with effector T cells underlie immunosuppression in NASH-HCC and are an actionable target.

TRIP6 disrupts tight junctions to promote metastasis and drug resistance and is a therapeutic target in colorectal cancer.

Metastasis is the primary cause of death in colorectal cancer (CRC). Thyroid hormone receptor interacting protein 6 (TRIP6) is an adaptor protein that regulates cell motility. Here, we aim to elucidate the role of TRIP6 in driving CRC tumorigenesis and metastasis and evaluate its potential as a therapeutic target. TRIP6 mRNA is up-regulated in CRC compared to adjacent normal tissues in three independent cohorts (all P < 0.0001), especially in liver metastases (P < 0.001). High TRIP6 expression predicts poor prognosis of CRC patients in our cohort (P = 0.01) and TCGA cohort (P = 0.02). Colon-specific TRIP6 overexpression (Trip6KIVillin-Cre) in mice accelerated azoxymethane (AOM)-induced CRC (P < 0.05) and submucosal invasion (P < 0.0001). In contrast, TRIP6 knockout (Trip6+/- mice) slowed tumorigenesis (P < 0.05). Consistently, TRIP6 overexpression in CRC cells promoted epithelial-mesenchymal transition (EMT), cell migration/invasion in vitro, and metastases in vivo (all P < 0.05), whereas knockdown of TRIP6 exerted opposite phenotypes. Mechanistically, TRIP6 interacted PDZ domain-containing proteins such as PARD3 to impair tight junctions, evidenced by decreased tight junction markers and gut permeability dysfunction, inhibit PTEN, and activate oncogenic Akt signaling. TRIP6-induced pro-metastatic phenotypes and Akt activation depends on PARD3. Targeting TRIP6 by VNP-encapsulated TRIP6-siRNA synergized with Oxaliplatin and 5-Fluorouracil to suppress CRC liver metastases. In conclusion, TRIP6 promotes CRC metastasis by directly interacting with PARD3 to disrupt tight junctions and activating Akt signaling. Targeting of TRIP6 in combination with chemotherapy is a promising strategy for the treatment of metastatic CRC.

Traditional Medicine Pien Tze Huang Suppresses Colorectal Tumorigenesis Through Restoring Gut Microbiota and Metabolites.

BACKGROUND & AIMS: Pien Tze Huang (PZH) is a well-established traditional medicine with beneficial effects against inflammation and cancer. We aimed to explore the chemopreventive effect of PZH in colorectal cancer (CRC) through modulating gut microbiota. METHODS: CRC mouse models were established by azoxymethane plus dextran sulfate sodium treatment or in Apcmin/+ mice treated with or without PZH (270 mg/kg and 540 mg/kg). Gut barrier function was determined by means of intestinal permeability assays and transmission electron microscopy. Fecal microbiota and metabolites were analyzed by means of metagenomic sequencing and liquid chromatography mass spectrometry, respectively. Germ-free mice or antibiotic-treated mice were used as models of microbiota depletion. RESULTS: PZH inhibited colorectal tumorigenesis in azoxymethane plus dextran sulfate sodium-treated mice and in Apcmin/+ mice in a dose-dependent manner. PZH treatment altered the gut microbiota profile, with an increased abundance of probiotics Pseudobutyrivibrio xylanivorans and Eubacterium limosum, while pathogenic bacteria Aeromonas veronii, Campylobacter jejuni, Collinsella aerofaciens, and Peptoniphilus harei were depleted. In addition, PZH increased beneficial metabolites taurine and hypotaurine, bile acids, and unsaturated fatty acids, and significantly restored gut barrier function. Transcriptomic profiling revealed that PZH inhibited PI3K-Akt, interleukin-17, tumor necrosis factor, and cytokine-chemokine signaling. Notably, the chemopreventive effect of PZH involved both microbiota-dependent and -independent mechanisms. Fecal microbiota transplantation from PZH-treated mice to germ-free mice partly recapitulated the chemopreventive effects of PZH. PZH components ginsenoside-F2 and ginsenoside-Re demonstrated inhibitory effects on CRC cells and primary organoids, and PZH also inhibited tumorigenesis in azoxymethane plus dextran sulfate sodium-treated germ-free mice. CONCLUSIONS: PZH manipulated gut microbiota and metabolites toward a more favorable profile, improved gut barrier function, and suppressed oncogenic and pro-inflammatory pathways, thereby suppressing colorectal carcinogenesis.

Targeting of SLC25A22 boosts the immunotherapeutic response in KRAS-mutant colorectal cancer.

KRAS is an important tumor intrinsic factor driving immune suppression in colorectal cancer (CRC). In this study, we demonstrate that SLC25A22 underlies mutant KRAS-induced immune suppression in CRC. In immunocompetent male mice and humanized male mice models, SLC25A22 knockout inhibits KRAS-mutant CRC tumor growth with reduced myeloid derived suppressor cells (MDSC) but increased CD8+ T-cells, implying the reversion of mutant KRAS-driven immunosuppression. Mechanistically, we find that SLC25A22 plays a central role in promoting asparagine, which binds and activates SRC phosphorylation. Asparagine-mediated SRC promotes ERK/ETS2 signaling, which drives CXCL1 transcription. Secreted CXCL1 functions as a chemoattractant for MDSC via CXCR2, leading to an immunosuppressive microenvironment. Targeting SLC25A22 or asparagine impairs KRAS-induced MDSC infiltration in CRC. Finally, we demonstrate that the targeting of SLC25A22 in combination with anti-PD1 therapy synergizes to inhibit MDSC and activate CD8+ T cells to suppress KRAS-mutant CRC growth in vivo. We thus identify a metabolic pathway that drives immunosuppression in KRAS-mutant CRC.

METTL3 drives NAFLD-related hepatocellular carcinoma and is a therapeutic target for boosting immunotherapy.

Non-alcoholic fatty liver disease (NAFLD) is an emerging risk factor of hepatocellular carcinoma (HCC). However, the mechanism and target therapy of NAFLD-HCC are still unclear. Here, we identify that the N6-methyladenosine (m6A) methyltransferase METTL3 promotes NAFLD-HCC. Hepatocyte-specific Mettl3 knockin exacerbated NAFLD-HCC formation, while Mettl3 knockout exerted the opposite effect in mice. Single-cell RNA sequencing revealed that METTL3 suppressed antitumor immune response by reducing granzyme B (GZMB+) and interferon gamma-positive (IFN-γ+) CD8+ T cell infiltration, thereby facilitating immune escape. Mechanistically, METTL3 mediates sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP) mRNA m6A to promote its translation, leading to the activation of cholesterol biosynthesis. This enhanced secretion of cholesterol and cholesteryl esters that impair CD8+ T cell function in the tumor microenvironment. Targeting METTL3 by single-guide RNA, nanoparticle small interfering RNA (siRNA), or pharmacological inhibitor (STM2457) in combination with anti-programmed cell death protein 1 (PD-1) synergized to reinvigorate cytotoxic CD8+ T cells and mediate tumor regression. Together, METTL3 is a therapeutic target in NAFLD-HCC, especially in conjunction with immune checkpoint blockade (ICB) therapy.

Carnobacterium maltaromaticum boosts intestinal vitamin D production to suppress colorectal cancer in female mice.

Carnobacterium maltaromaticum was found to be specifically depleted in female patients with colorectal cancer (CRC). Administration of C. maltaromaticum reduces intestinal tumor formation in two murine CRC models in a female-specific manner. Estrogen increases the attachment and colonization of C. maltaromaticum via increasing the colonic expression of SLC3A2 that binds to DD-CPase of this bacterium. Metabolomic and transcriptomic profiling unveils the increased gut abundance of vitamin D-related metabolites and the mucosal activation of vitamin D receptor (VDR) signaling in C. maltaromaticum-gavaged mice in a gut microbiome- and VDR-dependent manner. In vitro fermentation system confirms the metabolic cross-feeding of C. maltaromaticum with Faecalibacterium prausnitzii to convert C. maltaromaticum-produced 7-dehydrocholesterol into vitamin D for activating the host VDR signaling. Overall, C. maltaromaticum colonizes the gut in an estrogen-dependent manner and acts along with other microbes to augment the intestinal vitamin D production to activate the host VDR for suppressing CRC.

Crosstalk between gut microbiota and RNA N6-methyladenosine modification in cancer.

The gut microbiota plays a crucial role in regulating various host metabolic, immune, and neuroendocrine functions, and has a significant impact on human health. Several lines of evidence suggest that gut dysbiosis is associated with a variety of diseases, including cancer. The gut microbiota can impact the development and progression of cancer through a range of mechanisms, such as regulating cell proliferation and death, modulating the host immune response, and altering the host metabolic state. Gene regulatory programs are considered critical mediators between the gut microbiota and host phenotype, of which RNA N6-methyladenosine (m6A) modifications have attracted much attention recently. Aberrant m6A modifications have been shown to play a crucial role in cancer development. This review aims to provide an overview of the diverse roles of gut microbiota and RNA m6A modifications in cancer and highlight their potential interactions in cancer development.