m6A Reader HNRNPA2B1 Promotes Esophageal Cancer Progression via Up-Regulation of ACLY and ACC1

N6-methyladenosine (m6A) modification is the most abundant modification on eukaryotic RNA. In recent years, lots of studies have reported that m6A modification and m6A RNA methylation regulators were involved in cancer progression. However, the m6A level and its regulators in esophageal cancer (ESCA) remain poorly understood. In this study, we analyzed the expression of m6A regulators using The Cancer Genome Atlas data and found 14 of 19 m6A regulators are significantly increased in ESCA samples. Then we performed a univariate Cox regression analysis and LASSO (least absolute shrinkage and selection operator) Cox regression model to investigate the prognostic role of m6A regulators in ESCA, and the results indicated that a two-gene prognostic signature including ALKBH5 and HNRNPA2B1 could predict overall survival of ESCA patients. Moreover, HNRNPA2B1 is higher expressed in high-risk scores subtype of ESCA, indicating that HNRNPA2B1 may be involved in ESCA development. Subsequently, we confirmed that the level of m6A and HNRNPA2B1 was significantly increased in ESCA. We also found that HNRNPA2B1 expression positively correlated with tumor diameter and lymphatic metastasis of ESCA. Moreover, functional study showed that knockdown of HNRNPA2B1 inhibited the proliferation, migration, and invasion of ESCA. Mechanistically, we found that knockdown of HNRNPA2B1 inhibited the expression of de novo fatty acid synthetic enzymes, ACLY and ACC1, and subsequently suppressed cellular lipid accumulation. In conclusion, our study provides critical clues to understand the role of m6A and its regulators in ESCA. Moreover, HNRNPA2B1 functions as an oncogenic factor in promoting ESCA progression via up-regulation of fatty acid synthesis enzymes ACLY and ACC1, and it may be a promising prognostic biomarker and therapeutic target for human ESCA.

Emerging role of RNA methyltransferase METTL3 in gastrointestinal cancer

Gastrointestinal cancer, the most common solid tumor, has a poor prognosis. With the development of high-throughput sequencing and detection technology, recent studies have suggested that many chemical modifications of human RNA are involved in the development of human diseases, including cancer. m6A, the most abundant modification, was revealed to participate in a series of aspects of cancer progression. Recent evidence has shown that methyltransferase-like 3 (METTL3), the first identified and a critical methyltransferase, catalyzes m6A methylation on mRNA or non-coding RNA in mammals, affecting RNA metabolism. Abnormal m6A levels caused by METTL3 have been reported to be involved in different aspects of cancer development, including proliferation, apoptosis, and metastasis. In this review, we will shed light on recent findings regarding the biological function of METTL3 in gastrointestinal cancer and discuss future research directions and potential clinical applications of METTL3 for gastrointestinal cancer.

Stabilization of IGF2BP1 by USP10 promotes breast cancer metastasis via CPT1A in an m6A-dependent manner

Metastasis leads to the vast majority of breast cancer mortality. Increasing evidence has shown that N6-methyladenosine (m6A) modification and its associated regulators play a pivotal role in breast cancer metastasis. Here, we showed that overexpression of the m6A reader IGF2BP1 was clinically correlated with metastasis in breast cancer patients. Moreover, IGF2BP1 promoted distant metastasis in vitro and in vivo. Mechanistically, we first identified USP10 as the IGF2BP1 deubiquitinase. USP10 can bind to, deubiquitinate, and stabilize IGF2BP1, resulting in its higher expression level in breast cancer. Furthermore, by MeRIP-seq and experimental verification, we found that IGF2BP1 directly recognized and bound to the m6A sites on CPT1A mRNA and enhanced its stability, which ultimately mediated IGF2BP1-induced breast cancer metastasis. In clinical samples, USP10 levels correlated with IGF2BP1 and CPT1A levels, and breast cancer patients with high levels of USP10, IGF2BP1, and CPT1A had the worst outcome. Therefore, these findings suggest that the USP10/IGF2BP1/CPT1A axis facilitates breast cancer metastasis, and this axis may be a promising prognostic biomarker and therapeutic target for breast cancer.

The emerging roles of SUMOylation in the tumor microenvironment and therapeutic implications

Tumor initiation, progression, and response to therapies depend to a great extent on interactions between malignant cells and the tumor microenvironment (TME), which denotes the cancerous/non-cancerous cells, cytokines, chemokines, and various other factors around tumors. Cancer cells as well as stroma cells can not only obtain adaption to the TME but also sculpt their microenvironment through a series of signaling pathways. The post-translational modification (PTM) of eukaryotic cells by small ubiquitin-related modifier (SUMO) proteins is now recognized as a key flexible pathway. Proteins involved in tumorigenesis guiding several biological processes including chromatin organization, DNA repair, transcription, protein trafficking, and signal conduction rely on SUMOylation. The purpose of this review is to explore the role that SUMOylation plays in the TME formation and reprogramming, emphasize the importance of targeting SUMOylation to intervene in the TME and discuss the potential of SUMOylation inhibitors (SUMOi) in ameliorating tumor prognosis.

The cancer-testis lncRNA LINC01977 promotes HCC progression by interacting with RBM39 to prevent Notch2 ubiquitination

Cancer-testis genes are involved in the occurrence and development of cancer, but the role of cancer-testis-associated lncRNAs (CT-lncRNAs) in hepatocellular carcinoma (HCC) remains to be explored. Here, we discovered a novel CT-lncRNA, LINC01977, based on the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases. LINC01977 was exclusively expressed in testes and highly expressed in HCC. High LINC01977 levels correlated with poorer overall survival (OS) in individuals with HCC. Functional assays showed that LINC01977 promoted HCC growth and metastasis in vitro and in vivo. Mechanistically, LINC01977 directly bound to RBM39 to promote the further entry of Notch2 into the nucleus, thereby preventing the ubiquitination and degradation of Notch2. Furthermore, the RNA binding protein IGF2BP2, one of the m6A modification readers, enhanced the stability of LINC01977, resulting in its high level in HCC. Therefore, the data suggest that LINC01977 interacts with RBM39 and promotes the progression of HCC by inhibiting Notch2 ubiquitination and degradation, indicating that LINC01977 may be a potential biomarker and therapeutic target for HCC patients.

Prognostic and predictive role of a metabolic rate-limiting enzyme signature in hepatocellular carcinoma

OBJECTIVES

Abnormal expression of metabolic rate-limiting enzymes drives the occurrence and progression of hepatocellular carcinoma (HCC). This study aimed to elucidate the comprehensive model of metabolic rate-limiting enzymes associated with the prognosis of HCC.

MATERIALS AND METHODS

HCC animal model and TCGA project were used to screen out differentially expressed metabolic rate-limiting enzyme. Cox regression, least absolute shrinkage and selection operation (LASSO) and experimentally verification were performed to identify metabolic rate-limiting enzyme signature. The area under the receiver operating characteristic curve (AUC) and prognostic nomogram were used to assess the efficacy of the signature in the three HCC cohorts (TCGA training cohort, internal cohort and an independent validation cohort).

RESULTS

A classifier based on three rate-limiting enzymes (RRM1, UCK2 and G6PD) was conducted and serves as independent prognostic factor. This effect was further confirmed in an independent cohort, which indicated that the AUC at year 5 was 0.715 (95% CI: 0.653-0.777) for clinical risk score, whereas it was significantly increased to 0.852 (95% CI: 0.798-0.906) when combination of the clinical with signature risk score. Moreover, a comprehensive nomogram including the signature and clinicopathological aspects resulted in significantly predict the individual outcomes.

CONCLUSIONS

Our results highlighted the prognostic value of rate-limiting enzymes in HCC, which may be useful for accurate risk assessment in guiding clinical management and treatment decisions.

RP11-296E3.2 acts as an important molecular chaperone for YBX1 and promotes colorectal cancer proliferation and metastasis by activating STAT3

BACKGROUND

RP11-296E3.2 is a novel long noncoding RNA (lncRNA) associated with colorectal cancer (CRC) metastasis, that was reported in our previous clinical studies. However, the mechanisms of RP11-296E3.2 in colorectal tumorigenesis remain elusive.

METHODS

RNA sequencing (RNA-seq), Fluorescence in situ hybridization (FISH), Transwell assays and others, were performed to evaluate the function of RP11-296E3.2 for proliferation and metastasis in vitro. In situ and metastatic tumor models were performed to evaluate the function of RP11-296E3.2 for proliferation and metastasis in vivo. RNA-pulldown, RNA-interacting protein immunoprecipitation (RIP), tissue microarray (TMA) assay, a luciferase reporter assay, chromatin immunoprecipitation (ChIP) and others were performed to explore the mechanisms by which RP11-296E3.2 regulates CRC tumorigenesis.

RESULTS

RP11-296E3.2 was confirmed to be associated with CRC cell proliferation and metastasis in vitro and in vivo. Mechanistically, RP11-296E3.2 directly bound to recombinant Y-Box Binding Protein 1 (YBX1) and enhanced signal transducer and activator of transcription 3 (STAT3) transcription and phosphorylation. YBX1 promoted the CRC cell proliferation and migration, while knockdown of RP11-296E3.2 attenuated the effects of YBX1 on CRC cell proliferation, and metastasis and the expression of several related downstream genes. We are the first to discover and confirm the existence of the YBX1/STAT3 pathway, a pathway dependent on RP11-296E3.2.

CONCLUSION

Together, these novel findings show that the RP11-296E3.2/YBX1 pathway promotes colorectal tumorigenesis and progression by activating STAT3 transcription and phosphorylation, and suggest that RP11-296E3.2 is a potential diagnostic biomarker and therapeutic target in CRC.

Glucose homeostasis controls N-acetyltransferase 10-mediated ac4C modification of HK2 to drive gastric tumorigenesis

Rationale: Abnormal metabolic states contribute to a variety of diseases, including cancer. RNA modifications have diverse biological functions and are implicated in cancer development, including gastric cancer (GC). However, the direct relationship between glucose homeostasis and 4-acetylcytosine (ac4C) modification in GC remains unclear. Methods: The prognostic value of RNA acetyltransferase NAT10 expression was evaluated in a human GC cohort. Additionally, preoperative PET/CT data from GC patients and Micro-PET/CT imaging of mice were employed to assess the relationship between NAT10 and glucose metabolism. The biological role of NAT10 in GC was investigated through various experiments, including GC xenografts, organoids, and a conditional knockout (cKO) mouse model. The underlying mechanisms were examined using dot blotting, immunofluorescence staining, co-immunoprecipitation, and high-throughput sequencing, among other techniques. Results: Glucose deprivation activates the autophagy-lysosome pathway, leading to the degradation of NAT10 by enhancing its interaction with the sequestosome 1 (SQSTM1)/microtubule-associated protein 1 light chain 3 alpha (LC3) complex, ultimately resulting in a reduction of ac4C modification. Furthermore, the levels of ac4C and NAT10 are elevated in GC tissues and correlate with poor prognosis. A strong correlation exists between NAT10 levels and 18F-FDG uptake in GC patients. Furthermore, NAT10 drives glycolytic metabolism and gastric carcinogenesis in vitro and in vivo. Mechanistically, NAT10 stimulates ac4C modification at the intersection of the coding sequence (CDS) and 3' untranslated region (3'UTR) of hexokinase 2 (HK2) mRNA, enhancing its stability and activating the glycolytic pathway, thereby driving gastric tumorigenesis. Conclusion: Our findings highlight the critical crosstalk between glucose homeostasis and the ac4C epitranscriptome in gastric carcinogenesis. This finding offers a potential strategy of targeting NAT10/HK2 axis for the treatment of GC patients, especially those with highly active glucose metabolism.

ABCF1-K430-Lactylation promotes HCC malignant progression via transcriptional activation of HIF1 signaling pathway

Lysine lactylation plays critical roles in various diseases, including cancer. Our previous study showed that lactylation of non-histone ABCF1 may be involved in hepatocellular carcinoma (HCC) progression. In this study, we evaluated the prognostic value of ABCF1-K430la in HCC using immunohistochemical staining and performed amino acid point mutations, multi-omics crossover, and biochemical experiments to investigate its biological role and underlying mechanism. Additionally, we performed molecular docking on lactylation sites. ABCF1-K430la was highly expressed in HCC tissues and correlated with poor patient prognosis. Functionally, ABCF1-K430la promoted HCC growth and lung metastasis. Mechanistically, upon lactylation, E2 ubiquitin ligase activity of ABCF1 remained unaffected, and ABCF1 entered the nucleus, bound to the KDM3A promoter to upregulate its expression, and activated the KDM3A-H3K9me2-HIF1A axis, challenging the notion that ABCF1 functions exclusively in cytoplasmic protein translation. Notably, we discovered the existence of a lactate-ABCF1(430Kla)-HIF1A-lactate in HCC. A small-molecule drug screen targeting ABCF1-K430la revealed that tubuloside A inhibits ABCF1-K430la and suppresses HCC development. These findings demonstrate that elevated ABCF1-K430la expression promotes HCC development, suggesting it as a potential prognostic biomarker and therapeutic target for HCC.

NSUN5 Facilitates Hepatocellular Carcinoma Progression by Increasing SMAD3 Expression

Hepatocellular carcinoma (HCC) is characterized by frequent intrahepatic and distant metastases, resulting in a poor prognosis for patients. Epithelial-mesenchymal transition (EMT) plays a pivotal role in this process. However, the expression of NOP2/Sun RNA methyltransferase 5 (NSUN5) in HCC and its role in mediating EMT remain poorly understood. In this study, clinicopathological analyses are conducted across multiple independent HCC cohorts and induced tumor formation in Nsun5-knockout mice. The findings reveal an upregulation of NSUN5 expression in tumor tissues; conversely, the absence of Nsun5 hinders the malignant progression of HCC, indicating that NSUN5 may serve as a significant oncogene in HCC. Furthermore, elevated levels of NSUN5 enhance EMT processes within HCC cells. NSUN5-knockout cells exhibit reduced invasion and migration capabilities under both in vivo and in vitro conditions, while overexpression of NSUN5 yields opposing effects. Mechanistically, high levels of NSUN5 promote the enrichment of trimethylated histone H3 at lysine 4 (H3K4me3) at the promoter region of SMAD3 through recruitment of the WDR5, thereby facilitating HCC metastasis via SMAD3-mediated EMT pathways. Collectively, this study identifies NSUN5 as a novel driver of metastasis in HCC and provides a theoretical foundation for potential therapeutic strategies against this malignancy.

NAT10 Promotes Gastric Cancer Liver Metastasis by Modulation of M2 Macrophage Polarization and Metastatic Tumor Cell Hepatic Adhesion

The relationship between patterns of RNA modifications and gastric cancer (GC) liver metastasis (GCLM) remains unclear. Here, by single-cell sequencing, clinical sample analysis, and mouse model studies, an abnormal increase in the expression of the RNA acetyltransferase N-acetyltransferase 10 (NAT10) in liver metastatic GC cells is identified. NAT10-mediated N4-acetylcytidine modification of CXCL2 and KLF5 mRNA increases their stability. Then, secreted CXCL2 is found to promote the infiltration and polarization of M2-like macrophages to produce oncostatin M, which transcriptionally activates NAT10 expression via STAT3 signaling. In addition, organoid models confirm that NAT10 promotes the adhesion of GC cells to hepatocytes. Mechanistically, KLF5 transcriptionally activates ITGαV, facilitating GC cell attachment to hepatocytes. Intriguingly, high expression of NAT10/KLF5 axis is associated with poor prognosis of GC patients and targeting this axis significantly reduces GCLM in preclinical murine models. Collectively, these findings suggest the clinical significance of NAT10 in developing targeted therapies for GC patients with liver metastasis.