m6A-Modified circTET2 Interacting with HNRNPC Regulates Fatty Acid Oxidation to Promote the Proliferation of Chronic Lymphocytic Leukemia

HNRNPC stabilizes m6A-modified AC145207.5 to accelerate tumorigenesis in colorectal cancer by impeding the Nrf2/GPX4 axis-mediated ferroptosis

Ferroptosis is an apoptosis-independent cell death pathway characterized by heightened lipid peroxidation, which shows promise for tumor suppression. Despite extensive research on long non-coding RNAs (LncRNAs) in ferroptosis, their role in colorectal cancer (CRC) remains underexplored. We investigated the upregulation of AC145207.5 and HNRNPC expression in CRC tissues through public dataset analysis and in-house validation, identifying them as having significant diagnostic potential. In vitro experiments including MTS assay, transwell, and colony formation, alongside in vivo studies using xenograft models, elucidated the synergistic carcinogenic role of the HNRNPC/AC145207.5 axis in promoting the malignant characteristics of CRC. Mechanistically, the m6A reader HNRNPC stabilized m6A-modified AC145207.5, contributing to its stabilization and upregulation. Consequently, AC145207.5 activated the Nrf2/GPX4 axis, resulting in increased GPX4 expression, inhibition of GPX4-mediated ferroptosis, and facilitation of CRC progression. Our findings underscore the clinical relevance of the HNRNPC/AC145207.5 axis in CRC and illuminate its regulatory role in ferroptosis, suggesting implications for targeted precision medicine in CRC.

Emerging roles for fatty acid oxidation in cancer

Fatty acid oxidation (FAO) denotes the mitochondrial aerobic process responsible for breaking down fatty acids (FAs) into acetyl-CoA units. This process holds a central position in the cancer metabolic landscape, with certain tumor cells relying primarily on FAO for energy production. Over the past decade, mounting evidence has underscored the critical role of FAO in various cellular processes such as cell growth, epigenetic modifications, tissue-immune homeostasis, cell signal transduction, and more. FAO is tightly regulated by multiple evolutionarily conserved mechanisms, and any dysregulation can predispose to cancer development. In this view, we summarize recent findings to provide an updated understanding of the multifaceted roles of FAO in tumor development, metastasis, and the response to cancer therapy. Additionally, we explore the regulatory mechanisms of FAO, laying the groundwork for potential therapeutic interventions targeting FAO in cancers within the metabolic landscape.

ADAR1-HNRNPL-Mediated CircCANX Decline Promotes Autophagy in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a characteristic chronic airway inflammatory disease that worsens over time, however, there are currently limited clinical therapeutics to suspend its progression. Circular RNAs (circRNAs), which have emerged as functional regulators in various diseases, including COPD, may server as new pharmacological targets in COPD. Here, it is identified a nuclear circRNA, circCANX, that is preferentially decreased in COPD. The linear splicing of CANX pre-mRNA, enhanced by the ADAR1-HNRNPL interaction, is responsible for the circCANX decline. Clinically, the higher circCANX expression is associated with a worse lung function index of FEV1/FVC among patients with COPD. CircCANX suppresses autophagy and stress granule (SG) formation to strengthen inflammation of COPD in vivo and in vitro. Mechanistically, circCANX recruits the tumor suppressor protein P53 (P53) mRNA and RNA helicase upstream frameshift 1 (UPF1) to form a ternary complex, which mediates P53 mRNA degradation through nonsense-mediated mRNA decay (NMD) process. Together, this study reveals an important circCANX-mediated regulatory mechanism in COPD, and provides new insights into the potential of circRNA-based drug and biomarker development for COPD.

Fatty acid metabolism shapes immune responses in chronic lymphocytic leukemia

BACKGROUND

Fatty acids serve as a crucial energy source for tumor cells during the progression of chronic lymphocytic leukemia (CLL). The present study aims to elucidate the characteristics of fatty acid metabolism (FAM) in CLL, construct a related prognostic score, and investigate the regulatory role and mechanisms of FAM in CLL development.

METHODS

Bulk RNA sequencing data from CLL patients and healthy controls were analyzed to identify differentially expressed fatty acid metabolic genes. FAM-score was constructed using Cox-LASSO regression and validated. Single-cell RNA sequencing was used to analyze the expression of key FAM genes in CLL immune cell subsets and investigate cellular communication. Functional assays, including cell viability, drug sensitivity, and oxygen consumption assays, were performed to assess the impact of fatty acid oxidation (FAO) inhibition on CLL cells.

RESULTS

Three FAM-related genes (LPL, SOCS3, CNR1) were identified with independent prognostic significance to construct the risk score. The FAM-score demonstrated superior prognostic performance compared to the Binet stage and was associated with established clinical prognostic markers. Single-cell analysis revealed distinct expression patterns of LPL, SOCS3, and CNR1 across CLL immune cell subsets. Cellular communication analysis highlighted the regulatory role of distinct B cell and Treg subsets in the CLL microenvironment. CLL patients with high FAM-score displayed distinct immune infiltration patterns, with increased FAO pathway activity. Inhibition of FAO reduced CLL cell viability, synergistically enhanced the efficacy of the PI3K inhibitor idelalisib.

CONCLUSION

The present study constructed a prognostic risk score based on FAM gene expression, revealing related immune phenotypic differences and exploring the regulatory role of FAO in CLL development. Targeting fatty acid metabolism potentially modulates the CLL immune microenvironment and synergistically enhances the efficacy of PI3K inhibitors.

Exploring the Roles of m6A-Modified circRNAs in Myasthenia Gravis Based on Multi-Omics Analysis

Myasthenia gravis (MG) is an autoimmune disease mediated by autoantibodies. The important roles of circRNAs modified by m6A methylation have been reported in the pathogenesis of other autoimmune diseases, but remain unclear in MG. To address this point, we collected peripheral blood mononuclear cells from six MG patients and six healthy controls and performed m6A‑circRNA epitranscriptomic microarray and RNA sequencing. Differentially m6A-modified circRNAs and differentially expressed genes (DEGs) were analyzed. A network was constructed containing 17 circRNAs, 30 miRNAs, and 34 DEGs. The GSE85452 dataset was downloaded. DEGs that were differentially expressed in the GSE85452 dataset were selected as seed genes. Finally, four candidate m6A-modified circRNAs (hsa_circ_0084735, hsa_circ_0018652, hsa_circ_0025731, and hsa_circ_0030997) were identified through a random walk with restart. We found that they had different degree correlations with different immune cells. The results of MeRIP-qPCR showed that the m6A methylated levels of hsa_circ_0084735 and hsa_circ_0025731 were downregulated in MG patients, while the other two circRNAs were not significantly different between MG and control group. For the first time, we explored the pathogenesis of MG at the epigenetic transcriptome level. Our results will open new perspectives for MG research and identify potential biomarkers and therapeutic targets for MG.

Mechanisms and therapeutic implications of gene expression regulation by circRNA-protein interactions in cancer

Circular RNAs (circRNAs) have garnered substantial attention due to their distinctive circular structure and gene regulatory functions, establishing them as a significant class of functional non-coding RNAs in eukaryotes. Studies have demonstrated that circRNAs can interact with RNA-binding proteins (RBPs), which play crucial roles in tumorigenesis, metastasis, and drug response in cancer by influencing gene expression and altering the processes of tumor initiation and progression. This review aims to summarize the recent advances in research on circRNA-protein interactions (CPIs) and discuss the functions and mode of action of CPIs at various stages of gene expression, including transcription, splicing, translation, and post-translational modifications in the context of cancer. Additionally, we explore the role of CPIs in tumor drug resistance to gain a deeper understanding of their potential applications in the development of new anti-cancer therapeutic approaches.

Fatty acid metabolism: A new target for nasopharyngeal carcinoma therapy

Lipid metabolic reprogramming is considered one of the most prominent metabolic abnormalities in cancer, and fatty acid metabolism is a key aspect of lipid metabolism. Recent studies have shown that fatty acid metabolism and its related lipid metabolic pathways play important roles in the malignant progression of nasopharyngeal carcinoma (NPC). NPC cells adapt to harsh environments by enhancing biological processes such as fatty acid metabolism, uptake, production, and oxidation, thereby accelerating their growth. In addition, the reprogramming of fatty acid metabolism plays a central role in the tumor microenvironment (TME) of NPC, and the phenotypic transformation of immune cells is closely related to fatty acid metabolism. Moreover, the reprogramming of fatty acid metabolism in NPC contributes to immune escape, which significantly affects disease treatment, progression, recurrence, and metastasis. This review explores recent advances in fatty acid metabolism in NPC and focuses on the interconnections among metabolic reprogramming, tumor immunity, and corresponding therapies. In conclusion, fatty acid metabolism represents a potential target for NPC treatment, and further exploration is needed to develop strategies that target the interaction between fatty acid metabolic reprogramming and immunotherapy.

N6-methyladenosine RNA methylation, a new hallmark of metabolic reprogramming in the immune microenvironment

N6-methyladenosine is one of the most common and reversible post-transcriptional modifications in eukaryotes, and it is involved in alternative splicing and RNA transcription, degradation, and translation. It is well known that cancer cells acquire energy through metabolic reprogramming to exhibit various biological behaviors. Moreover, numerous studies have demonstrated that m6A induces cancer metabolic reprogramming by regulating the expression of core metabolic genes or by activating metabolic signaling pathways. Meanwhile, m6A modifications and related regulators are key targets in the regulation of immune effects. We further summarize how m6A modifications contribute to tumor metabolism, and how these events affect the tumor immune microenvironment, with a specific focus on different cell types. Finally, we focus on the specific applications of this field to tumor immunotherapy. We review the potential role of m6A in metabolic reprogramming of tumor immune microenvironment and its regulatory mechanism, with the aim of providing new targets for tumor metabolic regulation and immunotherapy.

The crosstalk between alternative splicing and circular RNA in cancer: pathogenic insights and therapeutic implications

RNA splicing is a fundamental step of gene expression. While constitutive splicing removes introns and joins exons unbiasedly, alternative splicing (AS) selectively determines the assembly of exons and introns to generate RNA variants corresponding to the same transcript. The biogenesis of circular RNAs (circRNAs) is inextricably associated with AS. Back-splicing, the biogenic process of circRNA, is a special form of AS. In cancer, both AS and circRNA deviate from the original track. In the present review, we delve into the intricate interplay between AS and circRNAs in the context of cancer. The relationship between AS and circRNAs is intricate, where AS modulates the biogenesis of circRNAs and circRNAs in return regulate AS events. Beyond that, epigenetic and posttranscriptional modifications concurrently regulate AS and circRNAs. On the basis of this modality, we summarize current knowledge on how splicing factors and other RNA binding proteins regulate circRNA biogenesis, and how circRNAs interact with splicing factors to influence AS events. Specifically, the feedback loop regulation between circRNAs and AS events contributes greatly to oncogenesis and cancer progression. In summary, resolving the crosstalk between AS and circRNA will not only provide better insight into cancer biology but also provoke novel strategies to combat cancer.

Recent Progress of CircRNAs in Hematological Malignancies

Circular RNAs (circRNAs) are now recognized as key regulators in the epigenetic control of genetic expression, being involved in a wide range of cellular activities such as proliferation, differentiation, and apoptosis. Their unique closed-loop structure endows them with stability and resistance to exonuclease degradation, making them not only key regulatory molecules within the cell but also promising biomarkers for disease diagnosis and prognosis, particularly in hematological malignancies. This review comprehensively explores the role of circRNAs in the pathogenesis, progression, and therapeutic resistance of common hematological malignancies. Furthermore, the review delves into the prognostic significance of circRNAs, underscoring their potential in predicting disease outcomes and treatment response. Given their extensive involvement in cancer biology, circRNAs present a frontier for novel therapeutic strategies.

Identification of RNA-binding protein hnRNP C targeting the 3'UTR of the TAP-associated glycoprotein tapasin in melanoma

Deregulation or loss of the human leukocyte antigen class I (HLA-I) molecules on tumor cells leading to inhibition of CD8+ T cell recognition is an important tumor immune escape strategy, which could be caused by a posttranscriptional control of molecules in the HLA-I pathway mediated by RNA-binding proteins (RBPs). So far, there exists only limited information about the interaction of RBPs with HLA-I-associated molecules, but own work demonstrated a binding of the heterogeneous ribonucleoprotein C (hnRNP C) to the 3' untranslated region (UTR) of the TAP-associated glycoprotein tapasin (tpn). In this study, in silico analysis of pan-cancer TCGA datasets revealed that hnRNP C is higher expressed in tumor specimens compared to corresponding normal tissues, which is negatively correlated to tpn expression, T cell infiltration and the overall survival of tumor patients. Functional analysis demonstrated an upregulation of tpn expression upon siRNA-mediated downregulation of hnRNP C, which is accompanied by an increased HLA-I surface expression. Thus, hnRNP C has been identified to target tpn and its inhibition could improve the HLA-I surface expression on melanoma cells suggesting its use as a possible biomarker for T-cell-based tumor immunotherapies.

m6A Reader HNRNPC Facilitates Adipogenesis by Regulating Cytoskeletal Remodeling through Enhanced Lcp1 mRNA Stability

Reduced adipogenesis is a prominent characteristic of aging adipose tissue and is closely tied to the development of metabolic disorders associated with aging. Epigenetic modification plays a crucial role in the aging process, yet the role of N6-methyladenosine (m6A), the most prevalent RNA modification, in regulating adipose tissue aging remains uncertain. Our study found that levels of m6A and its recognition protein, heterogeneous nuclear ribonucleoprotein C (HNRNPC), decrease in adipose tissue as individuals age. Lower levels of HNRNPC were also linked to reduced adipogenesis during aging. Through loss and gain of function experiments with HNRNPC, we established a positive correlation between HNRNPC and adipogenesis in vitro. Hnrnpc-APKO mice displayed decreased adipogenesis, increased insulin resistance, elevated expression of aging-related and inflammation-related genes, decreased lipogenesis-related genes, and other metabolic disorders compared to their littermates. Additionally, we discovered that HNRNPC facilitated the stability of lymphocyte cytosolic protein 1 (Lcp1) mRNA by binding to the m6A motif of LCP1. Overexpression of LCP1 mitigated the inhibition of adipogenesis caused by decreased HNRNPC through modulation of cytoskeletal remodeling. Finally, our findings demonstrate that anti-aging treatments could enhance HNRNPC levels. In conclusion, HNRNPC is positively associated with reduced adipogenesis during aging, and increacing HNRNPC levels through anti-aging treatments highlights its potential as a therapeutic target for addressing metabolic imbalances in adipose tissue related to aging.

Unveiling the Impact of ApoF Deficiency on Liver and Lipid Metabolism: Insights from Transcriptome-Wide m6A Methylome Analysis in Mice

Lipid metabolism participates in various physiological processes and has been shown to be connected to the development and progression of multiple diseases, especially metabolic hepatopathy. Apolipoproteins (Apos) act as vectors that combine with lipids, such as cholesterol and triglycerides (TGs). Despite being involved in lipid transportation and metabolism, the critical role of Apos in the maintenance of lipid metabolism has still not been fully revealed. This study sought to clarify variations related to m6A methylome in ApoF gene knockout mice with disordered lipid metabolism based on the bioinformatics method of transcriptome-wide m6A methylome epitranscriptomics. High-throughput methylated RNA immunoprecipitation sequencing (MeRIP-seq) was conducted in both wild-type (WT) and ApoF knockout (KO) mice. As a result, the liver histopathology presented vacuolization and steatosis, and the serum biochemical assays reported abnormal lipid content in KO mice. The m6A-modified mRNAs were conformed consensus sequenced in eukaryotes, and the distribution was enriched within the coding sequences and 3' non-coding regions. In KO mice, the functional annotation terms of the differentially expressed genes (DEGs) included cholesterol, steroid and lipid metabolism, and lipid storage. In the differentially m6A-methylated mRNAs, the functional annotation terms included cholesterol, TG, and long-chain fatty acid metabolic processes; lipid transport; and liver development. The overlapping DEGs and differential m6A-modified mRNAs were also enriched in terms of lipid metabolism disorder. In conclusion, transcriptome-wide MeRIP sequencing in ApoF KO mice demonstrated the role of this crucial apolipoprotein in liver health and lipid metabolism.

Circular RNA as Diagnostic and Prognostic Biomarkers in Hematological Malignancies:Systematic Review

Objectives: While various serum and tissue biomarkers have been explored for tumor diagnosis, the sensitivity and specificity have not yield optimal results. Circular RNAs (circRNAs) are more stable, conserved, and tissue-specific than linear RNA. Recent reports indicate that circRNAs could serve as potential biomarkers in the diagnosis or/and prognosis of tumors. In this study, we systematically examined the relationship between circRNA expression and diagnostic and prognostic outcomes in patients with hematological tumors. Methods: We searched several databases, including Google Scholar, MEDLINE, Scopus, PubMed, Embase, ScienceDirect, Ovid-Medline, Chinese National Knowledge Infrastructure, WanFang and SinoMed, with a cutoff date of June 12, 2024. The study protocol was PROSPERO (CRD42020188627). Result: A total of 73 studies were included in our review, comprising 39 diagnostic studies and 65 prognostic studies. Clinical parameters were assessed based on pooled adds ratios and 95% confidence intervals (CIs). Overall survival (OS) was evaluated using hazard ratios (HRs) and 95% CIs. The pooled area under the curve was 0.86, indicating the potential to identify hematological tumor patients, with sensitivity and specificity of 79% each. The diagnostic score for circRNAs related to hematological malignancies was 2.12. Notably, different hematological malignancies subgroups displayed varying prognoses. Specifically, lymphoid leukemia circRNA showed a negative impacct on prognosis (HR = 1.25, 95% CI: 1.10-1.43, P < 0.001). Conclusion: Our findings provide compelling evidence that circRNA may be serve as a promising alternative for the diagnosis and prognosis of hematological tumors.