N6-methyladenosine demethylase FTO enhances chemo-resistance in colorectal cancer through SIVA1-mediated apoptosis

Interplay of m6A RNA methylation and gut microbiota in modulating gut injury

The gut microbiota undergoes continuous variations among individuals and across their lifespan, shaped by diverse factors encompassing diet, age, lifestyle choices, medication intake, and disease states. These microbial inhabitants play a pivotal role in orchestrating physiological metabolic pathways through the production of metabolites like bile acids, choline, short-chain fatty acids, and neurotransmitters, thereby establishing a dynamic "gut-organ axis" with the host. The intricate interplay between the gut microbiota and the host is indispensable for gut health, and RNA N6-methyladenosine modification, a pivotal epigenetic mark on RNA, emerges as a key player in this process. M6A modification, the most prevalent internal modification of eukaryotic RNA, has garnered significant attention in the realm of RNA epigenetics. Recent findings underscore its potential to influence gut microbiota diversity and intestinal barrier function by modulating host gene expression patterns. Conversely, the gut microbiota, through its impact on the epigenetic landscape of host cells, may indirectly regulate the recruitment and activity of RNA m6A-modifying enzymes. This review endeavors to delve into the biological functions of m6A modification and its consequences on intestinal injury and disease pathogenesis, elucidating the partial possible mechanisms by which the gut microbiota and its metabolites maintain host intestinal health and homeostasis. Furthermore, it also explores the intricate crosstalk between them in intestinal injury, offering a novel perspective that deepens our understanding of the mechanisms underlying intestinal diseases.

A novel FTO-targeting nanodrug induces disulfidptosis and ameliorates the suppressive tumor immune environment to treat uveal melanoma

Uveal melanoma (UM) is the most prevalent primary ocular malignancy in adults, with high lethality and limited effective treatment options. Despite identified driver mutations in GNAQ, GNA11, and BAP1, therapeutic advancements have been minimal. This study highlights the pivotal role of N6-methyladenosine (m6A) modifications in UM pathogenesis and progression, focusing on the demethylase FTO as a therapeutic target. Elevated FTO expression in UM tissues correlates with decreased m6A levels, increased aggressiveness, and poor prognosis. The FTO inhibitor meclofenamic acid (MA) restored m6A levels, upregulated SLC7A11, and induced disulfidptosis, a unique form of cell death triggered by GSH depletion and NADPH consumption. To address MA's limitations in bioavailability and tumor targeting, we developed an MA-loaded nucleic acid nanodrug (SNAMA). SNAMA demonstrated effective tumor growth inhibition in orthotopic and metastatic UM models through GSH-responsive release and m6A-mediated disulfidptosis activation. Incorporating a PD-L1 aptamer into SNAMA further improved tumor targeting and immune modulation, enhancing therapeutic efficacy. This study identifies FTO as a critical target for UM therapy and introduces SNAMA-apt as a promising nanodrug. The findings offer a foundation for m6A-targeted approaches in UM and other malignancies, addressing bioavailability, targeting, and immune evasion challenges.

FTO triggers NLRP3/GSDMD-dependent pyroptosis to enhance cisplatin-sensitivity in ovarian cancer

Chemotherapy resistance is still the major impediment to poor prognosis of ovarian cancer (OC). The fat mass and obesity associated protein (FTO), as the first recognized RNA N6-methyladenosine (m6A) demethylase, was dysregulated in various tumors, but its effect on chemoresistance of OC remains unexplored. In this study, FTO expression in tissues and cells was measured by qPCR, IHC, and Western blot. Functional assays were performed, including CCK-8, colony formation, flow cytometry, Transwell assays, and LDH release. Pyroptosis-related proteins were detected by Western blot. MeRIP-qPCR was conducted to measure the m6A level. Finally, the effect of FTO on tumor growth and cisplatin (DDP) sensitivity of OC was checked in a mouse model. We found that FTO was significantly downregulated in OC tissues compared to adjacent normal tissues. In addition, the protein level of FTO was much lower in cisplatin (DDP)-resistant cells than in DDP-sensitive cells. Then, FTO overexpression in DDP-resistant cells decreased IC50 of DDP, increased cell apoptosis, and inhibited cell proliferation, migration, and invasion, whereas FTO silencing cells showed the opposite phenotypes. Moreover, FTO promoted the protein expressions of pyroptosis-related proteins, including NLRP3, cleaved-caspase-1, and GSDMD-NT, to enhance DDP sensitivity, as indicated by lower IC50. Furthermore, FTO activated NLRP3/Caspase-1/GSDMD-mediated pyroptosis in DDP-resistant cells. Mechanically, FTO successfully reduced the total m6A level and NLRP3 mRNA m6A modification to further increase DDP sensitivity in resistant cells. Finally, FTO overexpression promoted DDP-sensitivity and NLRP3 expression to inhibit tumorigenesis in a nude mice xenograft model. Together, our study inferred that FTO triggered NLRP3/Caspase-1/GSDMD-dependent pyroptosis by mediating NLRP3 m6A demethylation to enhance DDP-sensitivity and inhibit the progression of OC. This project indicates that FTO overexpression may be a potential strategy to overcome DDP resistance in OC.

FTO facilitates colorectal cancer chemoresistance via regulation of NUPR1-dependent iron homeostasis

Drug resistance in colorectal cancer (CRC) poses a major challenge for cancer therapy and stands as the primary cause of cancer-related mortality. The N6-methyladenosine (m6A) modification has emerged as a pivotal regulator in cancer biology, yet the precise m6A regulators that propel CRC progression and chemoresistance remain elusive. Our study established a significant correlation between m6A regulatory gene expression profiles and CRC severity. Notably, based on the knockout cellular and mouse model created by CRISPR/Cas9-mediated genome engineering, we identified m6A demethylase FTO emerged as a pivotal orchestrator of CRC chemoresistance through the regulation of NUPR1, a critical transcription factor involved in iron homeostasis via LCN2 and FTH1. Mechanistic study revealed that FTO stabilized NUPR1 mRNA by specifically targeting the +451 m6A site, thereby preventing YTHDF2-mediated degradation of NUPR1 mRNA. Moreover, the simultaneous targeting of FTO and NUPR1 dramatically enhanced the efficacy of chemotherapy in CRC cells. Our findings underscore the potential of modulating the m6A methylome to overcome chemoresistance and highlight the FTO-NUPR1 axis as a critical determinant in CRC pathobiology.

FTO Promotes Hepatocellular Carcinoma Progression by Mediating m6A Modification of BUB1 and Targeting TGF-βR1 to Activate the TGF-β Signaling Pathway

Background and Aims

Fat mass and obesity-associated protein (FTO) has been linked to various cancers, though its role in hepatocellular carcinoma (HCC) remains unclear. This study aimed to investigate FTO expression, its clinical relevance, functional role in HCC progression, and the underlying molecular mechanisms.

Methods

Quantitative reverse-transcription polymerase chain reaction and immunohistochemical analysis were used to assess FTO expression in HCC. Functional assays, including proliferation, invasion, and epithelial-mesenchymal transition studies, were conducted using HCC cell lines with FTO knockdown. N6-methyladenosine (m6A) RNA immunoprecipitation and RNA stability assays further elucidated the role of FTO in BUB1 mRNA methylation and stability. Co-immunoprecipitation studies were employed to confirm the interaction between BUB1 and TGF-βR1. In vivo studies in nude mice were conducted to evaluate tumor growth following FTO knockdown.

Results

FTO was significantly upregulated in HCC tissues compared to normal liver tissues, with higher expression observed in advanced tumor-node-metastasis stages and metastatic HCC. Elevated FTO correlated with poor overall survival in patients. Silencing FTO decreased HCC cell proliferation, colony formation, invasion, epithelial-mesenchymal transition, and tumor growth in nude mice. Mechanistically, FTO downregulation led to increased m6A modification of BUB1 mRNA, thereby promoting its degradation via the YTH domain family 2-dependent pathway and reducing BUB1 protein levels. Additionally, BUB1 physically interacted with TGF-βR1, activating downstream TGF-β signaling.

Conclusions

FTO is overexpressed in HCC and is associated with poor clinical outcomes. Mechanistically, FTO promotes HCC progression by stabilizing BUB1 mRNA through an m6A-YTH domain family 2-dependent pathway, which activates TGF-β signaling. Targeting the FTO-BUB1-TGF-βR1 regulatory network may offer a promising therapeutic strategy for HCC.

m6A methylation modification of RNA plays a significant role in the occurrence and development of colorectal cancer

Colorectal cancer is the third most common malignant tumor worldwide and ranks second in terms of mortality. N6-methyladenosine (m6A) modification is the most prevalent internal covalent modification in eukaryotic mRNA and is involved in various stages of RNA processing, including splicing, degradation, and export, playing a crucial role in the onset and progression of many diseases. The m6A modification is co-regulated by methyltransferases, demethylases, and methyl-binding proteins, and it has become a hot topic in cancer research. Based on a systematic review of existing studies on the role of m6A modification in colorectal cancer, this article further expands the research horizon in this field and effectively overcomes the limitations of existing reviews that only focus on discussing a single or a class of methylation regulators.

Exploring the dual role of SIVA1 in cancer biology

The intricate molecular mechanisms associated with cancer development continue to engage researchers due to the significant impact of the disease on global mortality. This review delves into the role of the apoptosis regulatory protein SIVA1, which has emerged as a significant player in cellular homeostasis. SIVA1, initially characterized as a pro-apoptotic protein interacting with the TNF receptor CD27, has since been implicated in various cellular contexts, revealing its complex functional dynamics. The SIVA1 gene, located on chromosome 14, encodes a protein containing distinctive structural features, including an amphipathic helix and a death domain homology region. Localization studies show that SIVA1 is present in both the cytoplasm and nucleus, with its expression linked to tumor differentiation. Investigations into SIVA1's interactions have uncovered its pro-apoptotic mechanisms, such as binding to anti-apoptotic proteins from the BCL2 family, thus promoting apoptosis under stress conditions. Interestingly, SIVA1 also exhibits tumor-promoting properties in specific cancer types, suggesting a dual role in apoptosis induction and tumor progression. As research progresses, understanding the regulatory mechanisms governing SIVA1's multifaceted functions could pave the way for novel therapeutic strategies aimed at manipulating its activity for improved cancer treatment outcomes. Future studies are warranted to clarify SIVA1's contextual roles and explore its potential clinical implications.

NRXN3 regulates pyroptosis in intrahepatic cholangiocarcinoma via mediating the phospho-dependent ubiquitination and degradation of caspase-3

INTRODUCTION

Intrahepatic cholangiocarcinoma (ICC) remains one of the most lethal malignancies with an increasing incidence worldwide. Gemcitabine has been considered the standard first-line chemotherapeutic agent for ICC but the therapeutic response is unsatisfactory due to the development of chemoresistance. Caspase-3-mediated pyroptosis has been reported to play significant roles in chemotherapeutic response but the relevant therapeutic strategy remains unstated due to the unclear molecular mechanisms under pyroptosis in ICC.

OBJECTIVES

This study was designed to comprehensively explore the crucial role and underlying mechanisms of NRXN3 in pyroptosis and chemosensitivity of ICC.

METHODS

We performed genome-scale CRISPR-Cas9 screen integrated with transcriptomic analysis to identify key regulators of pyroptosis and gemcitabine sensitivity in ICC. In vitro and in vivo experiments were employed to investigate the effects of NRXN3 on gemcitabine-induced pyroptosis. RNA-seq and IP-MS were conducted to explore the mechanisms of NRXN3-regulated pyroptosis and chemosensitivity.

RESULTS

NRXN3 was identified to be a critical contributor to pyroptosis and chemosensitivity in ICC. Low NRXN3 expression correlates with poor prognosis and worse therapeutic response. Mechanistically, NRXN3 competitively blocks caspase-3 binding to the RSK1 serine/threonine-protein kinase, thereby inhibiting RSK1-dependent phosphorylation of caspase-3 at T152. Inhibition of caspase-3 phosphorylation impairs its interaction with the ubiquitin ligase component FBXO1 and enhances its stability, thus facilitating caspase-3/GSDME-dependent pyroptotic cell death and chemosensitivity. Furthermore, administration of an RSK1 inhibitor or caspase-3 activator boosts the efficacy of gemcitabine in murine models of ICC.

CONCLUSION

NRXN3 plays a crucial role in maintaining chemotherapy-induced pyroptosis in ICC. Targeting the NRXN3/RSK1/FBXO1/caspase-3 axis emerges as a promising strategy for ICC treatment, with the potential to improve chemosensitivity and survival.

Integration of multi-omics data to unveil the molecular landscape and role of piRNAs in early-onset colorectal cancer

BACKGROUND

The incidence of early-onset colorectal cancer (EOCRC) (< 50 years) has been steadily rising, with a parallel increase in metastatic and invasive cases. To elucidate the molecular mechanisms underlying this aggressive phenotype, we performed comprehensive multi-omics profiling to delineate the distinct features of EOCRC, with a focus on key drivers of metastatic and invasive potential.

METHODS

We initially characterized the genome, epigenome, and transcriptome of tumors from 515 (69 EOCRC and 446 late-onset CRC [LOCRC]) cases in The Cancer Genome Atlas. Key candidate molecules were further validated using RNA-seq and scRNA-seq data. Multi-omics profiling revealed PIWIL1/piRNA as a hallmark of EOCRC, with further validation through in vitro functional assays, transcriptomic profiling, and Kaplan-Meier survival analysis.

RESULTS

EOCRC demonstrated a mutational landscape similar to that of LOCRC, with comparable oncogenic driver mutations and somatic copy-number alterations. However, EOCRC exhibited a higher frequency of deletion in chromosomes 6, 15, and 19 regions, along with metabolic reprogramming favoring aerobic glycolysis and lipid metabolism. Integrative transcriptomic and DNA methylation analyses identified six EOCRC-specific molecules, including PIWIL1. Notably, PIWIL1 was mainly expressed in epithelial cells, with lower expression in EOCRC versus LOCRC. Its downstream piRNAs (FR019019, FR019089, and FR132045) were also downregulated in EOCRC. Functional experiments demonstrated that FR019089/FR019019 overexpression suppressed migration and invasion. Clinically, low FR019089 levels correlated with significantly shorter progression-free and overall survival in EOCRC patients. Additionally, downstream pathways of FR019089 and FR019019 overexpression were enriched in anti-cancer-related signaling pathways.

CONCLUSIONS

Our multi-omics approach yields novel insights into the molecular underpinnings of EOCRC and we characterize the role of PIWIL1-associated piRNAs in modulating EOCRC metastasis and invasion. FR019089 shows promise as a prognostic biomarker with potential clinical utility in the risk stratification and management of EOCRC patients.

Analysis of Genotype and Expression of FTO and ALKBH5 in a MENA-Region Renal Cell Carcinoma Cohort

Background/Objectives: RNA-modifying proteins play a crucial role in the progression of cancer. The fat mass and obesity-associated protein (FTO) and alkB homolog 5 RNA demethylase (ALKBH5) are RNA-demethylating proteins that have contrasting effects in renal cell carcinoma (RCC) among different populations. This research investigates the genotype and expression levels of FTO and ALKBH5 in RCC patients from the Middle East and Northern Africa (MENA) region. Methods: Formalin-fixed paraffin-embedded samples from the kidney biopsies of RCC patients and controls were examined using targeted DNA sequencing, whole transcriptome profiling, and immunohistochemistry. Results: Our findings show that the rs11075995T variant in FTO is associated with a heightened risk of clear-cell RCC (ccRCC). ALKBH5 and FTO protein expression were significantly lower in ccRCC and chromophobe RCC (chRCC) patients but not in papillary RCC (pRCC) patients. In ccRCC, transcriptomic data revealed a significant downregulation of FTO (log2FC = -5.2, q < 0.001) and ALKBH5 (log2FC = -4.7, q < 0.001) compared to controls. A significant negative correlation was found in ccRCC between FTO expression and T allele frequency in rs11075995, suggesting that FTO expression is affected. Conclusions: This is the first demonstration of the association of the dysregulated expression of FTO and ALKBH5 in ccRCC and chRCC patients from the MENA region. FTO variant rs11075995T increased the risk of ccRCC and was negatively associated with FTO protein expression.

Role and mechanisms of m6A demethylases in digestive system tumors

Digestive system tumors are common malignancies in humans, often accompanied by high mortality and poor prognosis. Therefore, intensive research on the pathogenesis of digestive system tumors is imperative. N6-methyladenosine (m6A) is the most common RNA modification in eukaryotes and exerts regulatory effects on RNA expression and metabolism, including splicing, translation, stability, decay, and transport. m6A demethylases belong to the AlkB family of dioxygenases that can catalyze m6A demethylation. Accumulating evidence in recent years has shown that abnormal m6A levels caused by m6A demethylases play crucial roles in different aspects of human cancer development. In this review, we comprehensively summarize the recent findings on the functions and underlying molecular mechanisms of m6A demethylases in cell proliferation, apoptosis, migration, invasion, metastasis, angiogenesis, resistance to chemo- and radiotherapy, and the tumor immune microenvironment (TIME) of digestive system tumors. Furthermore, we discuss the therapeutic potential of targeting these m6A demethylases for treatment.

RNA N6-methyladenosine demethylase FTO promotes diabetic wound healing through TRIB3-mediated autophagy in an m6A-YTHDF2-dependent manner

N6-methyladenosine (m6A) RNA modification impaired autophagy results in delayed diabetic wound healing. In this study, it was found that fat mass and obesity-associated protein (FTO) was significantly downregulated in the epidermis of diabetic patients, STZ-induced mice and db/db mice (type I and II diabetic mice) with prolonged hyperglycemia, as well as in different types of keratinocyte cell lines treated with short-term high glucose medium. The knockout of FTO affected the biological functions of keratinocytes, including enhanced apoptosis, inhibited autophagy, and delayed wound healing, producing consistent results with high-glucose medium treatment. High-throughput analysis revealed that tribbles pseudokinase 3 (TRIB3) served as the downstream target gene of FTO. In addition, both in vitro and in vivo experiments, TRIB3 overexpression partially rescued biological functions caused by FTO-depletion, promoting keratinocyte migration and proliferation via autophagy. Epigenetically, FTO modulated m6A modification in the 3'UTR of TRIB3 mRNA and enhanced TRIB3 stability in a YTHDF2-dependent manner. Collectively, this study identifies FTO as an accelerator of diabetic wound healing and modulates autophagy via regulating TRIB3 in keratinocytes, thereby benefiting the development of a m6A-targeted therapy for refractory diabetic wounds.

Targeting CDK4/6 suppresses colorectal cancer by destabilizing YAP1

Colorectal cancer (CRC) is among the most prevalent and deadly cancers worldwide. The Yes-associated protein 1 (YAP1) is frequently dysregulated in cancers, contributing to cancer stemness, chemoresistance, and cancer-related death. However, strategies directly targeting YAP1 have not yet been successful because of the lack of active binding pockets and unregulated toxicity. In this study, our Food and Drug Administration (FDA)-approved drug screening reveals that abemaciclib, a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, dramatically promotes the proteasome-dependent degradation of YAP1, thereby inhibiting tumor progression in CRC cells and patient-derived xenograft models. We further identify deubiquitinating enzyme 3 (DUB3) as the bona fide deubiquitinase of YAP1 in CRC. Mechanistically, CDK4/6 directly phosphorylates DUB3 at Ser41, activating DUB3 to deubiquitinate and stabilize YAP1. Conversely, loss of Ser41 phosphorylation by CDK4/6 inhibition or Ser41A mutation, promotes YAP1 degradation and suppresses YAP1-driven tumor progression. Histological analysis shows a positive correlation between DUB3 and YAP1 expression in CRC specimens. Collectively, our study uncovers a novel oncogenic role of the CDK4/6-DUB3 pathway, which promotes YAP1 stabilization and tumor-promoting function, highlighting that targeting CDK4/6 offers a potential therapeutic strategy for CRC with aberrantly upregulated DUB3 and YAP1.

Copper-coordinated nanomedicine for the concurrent treatment of lung cancer through the induction of cuproptosis and apoptosis

The resistance of tumor cells to apoptosis often leads to chemoresistance and treatment failure in clinic. In this study, we have developed a Cu2+-coordinated lignosulfonate (CLS) /doxorubicin (DOX) biological complex (referred to as LCD) with the aim of overcoming cellular resistance to apoptosis for combined lung cancer therapy. The copper complexes modified by CLS exhibit significant water solubility and excellent in vivo biocompatibility. The proportion of copper in the composite is simultaneously increased. Due to the coordination and π-π stacking effects, the self-assembled LCD exhibits nanometer-scale particle size, a narrow and homogeneous grain distribution, as well as excellent dispersion stability. Furthermore, LCD has the potential to disassemble in the presence of high levels of glutathione (GSH) and low pH, leading to effective drug release. Cu2+-mediated cuproptosis can lead to the down-regulation of FDX1 and DLAT protein expression by reducing mitochondrial membrane potential, resulting in non-apoptotic programmed cell death (PCD) regardless of cellular resistance to apoptosis. Moreover, the released DOX not only exhibits a preference for localizing in the cell nucleus to induce apoptosis for combined chemotherapy, but also generates a substantial amount of H2O2. This H2O2 further produces ROS to induce apoptosis through Fenton reaction with Cu2+. LCD demonstrates significant superiority over monotherapy in inhibiting tumor growth while minimizing systemic toxicity through the combined action of cuproptosis and apoptosis. This study may provide a potential avenue for the advancement of self-delivery nanomedicine to overcome resistance to apoptosis in tumor therapy.

FOXF2 suppressed esophageal squamous cell carcinoma by reducing M2 TAMs via modulating RNF144A-FTO axis

Esophageal squamous cell carcinoma (ESCC) is one of the deadliest cancers because of its high invasiveness and low survival. Tumor-associated macrophages (TAMs) are closely associated with the tumor cell proliferation, metastasis and immunosuppression. As a member of the FOX family, forkhead box F2 (FOXF2) was down-regulated in ESCC. However, its role in ESCC and TAMs, as well as the underlying mechanism, remains unclear. We found that differentially expressed genes (DEGs) in ESCC were enriched in proliferation, migration, macrophage and cancer pathways. Among these DEGs, FOXF2 caught our eyes. FOXF2 was down-regulated in ESCC. Overexpression FOXF2 inhibited the proliferation of ESCC cells and the M2 polarization of TAMs, but silenced FOXF2 reversed these results. Notably, FOXF2 promoted the transcription of ring finger protein 144A (RNF144A), which is an E3 ubiquitin ligase, causing the ubiquitination and degradation of FTO Alpha-Ketoglutarate Dependent Dioxygenase (FTO), an N6-methyladenosine (m6A) demethylase. Furthermore, overexpression of FTO abolished the effects of FOXF2 on TAM polarization. In conclusion, FOXF2 alleviates ESCC via promoting the transcription of RNF144A which results in the ubiquitylation and degradation of FTO. Targeting FOXF2/RNF144A/FOT axis might be a possible strategy for the treatment of ESCC.

WTAP-mediated m6A modification regulates NLRP3/Caspase-1/GSDMD to inhibit pyroptosis and exacerbate colorectal cancer

Aim: Wilms' tumor 1-associating protein (WTAP), plays a part in colorectal cancer (CRC) progression. However, it is not yet known how WTAP affects cancer progression by influencing leukocyte rich repeat containing proteins (NLR) - family members 3 (NLRP3) - related inflammasomes.Materials & methods: We first validated the expression of WTAP in CRC at the tissue and cellular levels. Subsequently, by transfecting si-NC and si-WTAP into cells, we verified functions of WTAP in proliferation, invasion, migration and apoptosis of CRC cells. Finally, we analyzed the N6-methyladenosine (m6A) modification of NLRP3 by WTAP using methylated RNA immunoprecipitation (MeRIP)-qPCR technology, confirming that WTAP mediated the repression of NLRP3 inflammasome and the malignant progression of tumor cells.Results: WTAP was substantially upregulated in CRC tissues and cells. WTAP reinforced the migration, proliferation and invasion ability of CRC cells, and repressed apoptosis. Mechanistically, WTAP mediated the m6A modification of NLRP3, which suppressed the expression of NLRP3 and dampened the NLRP3/Caspase-1/GSDMD axis activation as well as pyroptosis, thereby facilitating the malignant progression of CRC.Conclusion: WTAP mediates m6A modification to modulate the repression of the NLRP3/Caspase-1/GSDMD axis in pyroptosis, reinforcing the malignant progression of CRC.

Decoding the epitranscriptome: a new frontier for cancer therapy and drug resistance

As the role of RNA modification in gene expression regulation and human diseases, the "epitranscriptome" has been shown to be an important player in regulating many physiological and pathological processes. Meanwhile, the phenomenon of cancer drug resistance is becoming more and more frequent, especially in the case of cancer chemotherapy resistance. In recent years, research on relationship between post-transcriptional modification and cancer including drug resistance has become a hot topic, especially the methylation of the sixth nitrogen site of RNA adenosine-m6A (N6-methyladenosine). m6A modification is the most common post-transcriptional modification of eukaryotic mRNA, accounting for 80% of RNA methylation modifications. At the same time, several other modifications of RNA, such as N1-methyladenosine (m1A), 5-methylcytosine (m5C), 3-methylcytosine (m3C), pseudouridine (Ψ) and N7-methylguanosine (m7G) have also been demonstrated to be involved in cancer and drug resistance. This review mainly discusses the research progress of RNA modifications in the field of cancer and drug resistance and targeting of m6A regulators by small molecule modulators, providing reference for future study and development of combination therapy to reverse cancer drug resistance.

Modulation of host N6-methyladenosine modification by gut microbiota in colorectal cancer

As a research hotspot in the field of molecular biology, N6-methyladenosine (m6A) modification has made progress in the treatment of colorectal cancer (CRC), leukemia and other cancers. Numerous studies have demonstrated that the tumour microenvironment (TME) regulates the level of m6A modification in the host and activates a series of complex epigenetic signalling pathways through interactions with CRC cells, thus affecting the progression and prognosis of CRC. However, with the diversity in the composition of TME factors, this action is reciprocal and complex. Encouragingly, some studies have experimentally revealed that the intestinal flora can alter CRC cell proliferation by directly acting on m6A and thereby altering CRC cell proliferation. This review summarizes the data, supporting the idea that the intestinal flora can influence host m6A levels through pathways such as methyl donor metabolism and thus affect the progression of CRC. We also review the role of m6A modification in the diagnosis, treatment, and prognostic assessment of CRC and discuss the current status, limitations, and potential clinical value of m6A modification in this field. We propose that additional in-depth research on m6A alterations in CRC patients and their TME-related targeted therapeutic issues will lead to better therapeutic outcomes for CRC patients.

FTO diversely influences sensitivity of neuroblastoma cells to various chemotherapeutic drugs

Chemotherapy resistance is a significant factor in treatment failure in patients with neuroblastoma (NB), and it directly affects patient prognosis. Therefore, identifying novel therapeutic targets to enhance chemosensitivity is essential to improve the cure rate and prognosis of patients with NB. In this study, we investigated the role of FTO in chemosensitivity of NB cells to various chemotherapeutic drugs. Our results showed that high FTO expression was positively correlated with increased survival probability and favorable prognostic factors in patients with NB. FTO overexpression inhibited cell proliferation, whereas FTO knockdown promoted cell proliferation in NB cells. FTO expression alteration had contrasting effects on NB cells' sensitivity to etoposide but had no significant impact on sensitivity to cisplatin. Downregulation of FTO reduced the sensitivity of NB cells to paclitaxel, whereas upregulation of FTO enhanced its sensitivity. Additionally, the sensitivities between patients with lower and higher FTO expression to various chemotherapeutic drugs or small-molecule inhibitors were different. Thus, FTO affects the sensitivities of NB cells differently depending on the different chemotherapeutic drugs and small-molecule inhibitors. This finding may guide physicians and patients choose the appropriate chemotherapeutic drugs or small-molecule inhibitors for treatment.

Role of the lncRNA/Wnt signaling pathway in digestive system cancer: a literature review

The long noncoding RNA (lncRNA)/Wingless (Wnt) axis is often dysregulated in digestive system tumors impacting critical cellular processes. Abnormal expression of specific Wnt-related lncRNAs such as LINC01606 (promotes motility), SLCO4A1-AS1 (promotes motility), and SH3BP5-AS1 (induces chemoresistance), plays a crucial role in these malignancies. These lncRNAs are promising targets for cancer diagnosis and therapy, offering new treatment perspectives. The lncRNAs, NEF and GASL1, differentially expressed in plasma show diagnostic potential for esophageal squamous cell carcinoma and gastric cancer, respectively. Additionally, Wnt pathway inhibitors like XAV-939 have demonstrated preclinical efficacy, underscoring their therapeutic potential. This review comprehensively analyzes the lncRNA/Wnt axis, highlighting its impact on cell proliferation, motility, and chemoresistance. By elucidating the complex molecular mechanisms of the lncRNA/Wnt axis, we aim to identify potential therapeutic targets for digestive system tumors to pave the way for the development of targeted treatment strategies.

Writers, readers, and erasers RNA modifications and drug resistance in cancer

Drug resistance in cancer cells significantly diminishes treatment efficacy, leading to recurrence and metastasis. A critical factor contributing to this resistance is the epigenetic alteration of gene expression via RNA modifications, such as N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), 7-methylguanosine (m7G), pseudouridine (Ψ), and adenosine-to-inosine (A-to-I) editing. These modifications are pivotal in regulating RNA splicing, translation, transport, degradation, and stability. Governed by "writers," "readers," and "erasers," RNA modifications impact numerous biological processes and cancer progression, including cell proliferation, stemness, autophagy, invasion, and apoptosis. Aberrant RNA modifications can lead to drug resistance and adverse outcomes in various cancers. Thus, targeting RNA modification regulators offers a promising strategy for overcoming drug resistance and enhancing treatment efficacy. This review consolidates recent research on the role of prevalent RNA modifications in cancer drug resistance, with a focus on m6A, m1A, m5C, m7G, Ψ, and A-to-I editing. Additionally, it examines the regulatory mechanisms of RNA modifications linked to drug resistance in cancer and underscores the existing limitations in this field.

Medicinal chemistry aspects of fat mass and obesity associated protein: structure, function and inhibitors

Adiposity and obesity-related proteins (FTO), the earliest identified mRNA N6-methyladenosine (m6A) demethylases, are known to play crucial roles in several biological processes. Therefore, FTO is a promising target for anticancer treatment. Understanding the biological functions and regulatory mechanisms of FTO targets can serve as guidelines for drug development. Despite significant efforts to develop FTO inhibitors, no specific small-molecule inhibitors have entered clinical trials so far. In this manuscript, we review the relationship between FTO and various cancers, the small-molecule inhibitors developed against FTO targets from the perspective of medicinal chemistry and other fields, and describe their structural optimization process and structure-activity relationship, providing clues for their future development direction.

Drug tolerant persister cell plasticity in cancer: A revolutionary strategy for more effective anticancer therapies

Non-genetic mechanisms have recently emerged as important drivers of anticancer drug resistance. Among these, the drug tolerant persister (DTP) cell phenotype is attracting more and more attention and giving a predominant non-genetic role in cancer therapy resistance. The DTP phenotype is characterized by a quiescent or slow-cell-cycle reversible state of the cancer cell subpopulation and inert specialization to stimuli, which tolerates anticancer drug exposure to some extent through the interaction of multiple underlying mechanisms and recovering growth and proliferation after drug withdrawal, ultimately leading to treatment resistance and cancer recurrence. Therefore, targeting DTP cells is anticipated to provide new treatment opportunities for cancer patients, although our current knowledge of these DTP cells in treatment resistance remains limited. In this review, we provide a comprehensive overview of the formation characteristics and underlying drug tolerant mechanisms of DTP cells, investigate the potential drugs for DTP (including preclinical drugs, novel use for old drugs, and natural products) based on different medicine models, and discuss the necessity and feasibility of anti-DTP therapy, related application forms, and future issues that will need to be addressed to advance this emerging field towards clinical applications. Nonetheless, understanding the novel functions of DTP cells may enable us to develop new more effective anticancer therapy and improve clinical outcomes for cancer patients.

Fat mass and obesity-associated protein (FTO)-induced upregulation of flotillin-2 (FLOT2) contributes to cancer aggressiveness in diffuse large B-cell lymphoma (DLBCL) via activating the PI3K/Akt/mTOR signal pathway

The role of fat mass and obesity-associated protein (FTO)-mediated N6-methyladenosine (m6A)-demethylation has been investigated in various types of cancers, but it is still unclear whether FTO participates in the progression of diffuse large B-cell lymphoma (DLBCL). Here, by conducting Real-Time qPCR and Western Blot analysis, we verified that FTO was especially enriched in the DLBCL cells (RCK-8, LY-3, DHL-6 and U2932) compared to normal WIL2S cells. Then, the overexpression and silencing vectors for FTO were delivered into the LY-3 and U2932 cells, and our functional experiments confirmed that silencing of FTO suppressed cell viability and division, and induced apoptotic cell death in the DLBCL cells, whereas FTO-overexpression exerted opposite effects. Further mechanical experiments showed that FTO demethylated m6A modifications in flotillin-2 (FLOT2) mRNA to sustain its stability for FLOT2 upregulation, and elevated FLOT2 subsequently increased the expression levels of phosphorylated PI3K (p-PI3K), p-Akt and p-mTOR to activate the tumor-initiating PI3K/Akt/mTOR signal pathway. Of note, FLOT2 also serve as an oncogene to enhance cancer malignancy in DLBCL, and the rescuing experiments showed that FTO-ablation induced suppressing effects on the malignant phenotypes in DLBCL were all abrogated by overexpressing FLOT2. Taken together, those data hinted that FTO-mediated m6A-demethylation upregulated FLOT2 to activate the downstream PI3K/Akt/mTOR signal pathway, leading to the aggressiveness of DLBCL, which potentially provided diagnostic, therapeutic and prognostic biomarkers for DLBCL.

Rhein exerts anti-multidrug resistance in acute myeloid leukemia via targeting FTO to inhibit AKT/mTOR

Chemotherapy failure and resistance are the leading causes of mortality in patients with acute myeloid leukemia (AML). However, the role of m6A demethylase FTO and its inhibitor rhein in AML and AML drug resistance is unclear. Therefore, this study aimed to investigate the antileukemic effect of rhein on AML and explore its potential mechanisms underlying drug resistance. Bone marrow fluid was collected to assess FTO expression in AML. The Cell Counting Kit 8 reagent was used to assess cell viability. Migration assays were conducted to assess the cell migration capacity. Flow cytometry was used to determine the apoptotic effects of rhein and western blot analysis was used to detect protein expression. Online SynergyFinder software was used to calculate the drug synergy scores. The in-vivo antileukemic effect of rhein was assessed in an AML xenograft mouse model. We analyzed different types of AML bone marrow specimens to confirm that FTO is overexpressed in AML, particularly in cases of multidrug resistance. Subsequently, we conducted in-vivo and in-vitro investigations to explore the pharmacological activity and mechanism of rhein in AML and AML with multidrug resistance. The findings demonstrated that rhein effectively suppressed the proliferation and migration of AML cells in a time- and dose-dependent manner and induced apoptosis. Rhein targets FTO, inhibits the AKT/mTOR pathway, and exhibits synergistic antitumor effects when combined with azacitidine. This study elucidates the significant role of FTO and its inhibitor rhein in AML and AML with multidrug resistance, providing new insights for overcoming multidrug resistance in AML.

WTAP and m6A-modified circRNAs modulation during stress response in acute myeloid leukemia progenitor cells

N6-methyladenosine (m6A) is one of the most prevalent and conserved RNA modifications. It controls several biological processes, including the biogenesis and function of circular RNAs (circRNAs), which are a class of covalently closed-single stranded RNAs. Several studies have revealed that proteotoxic stress response induction could be a relevant anticancer therapy in Acute Myeloid Leukemia (AML). Furthermore, a strong molecular interaction between the m6A mRNA modification factors and the suppression of the proteotoxic stress response has emerged. Since the proteasome inhibition leading to the imbalance in protein homeostasis is strictly linked to the stress response induction, we investigated the role of Bortezomib (Btz) on m6A regulation and in particular its impact on the modulation of m6A-modified circRNAs expression. Here, we show that treating AML cells with Btz downregulated the expression of the m6A regulator WTAP at translational level, mainly because of increased oxidative stress. Indeed, Btz treatment promoted oxidative stress, with ROS generation and HMOX-1 activation and administration of the reducing agent N-acetylcysteine restored WTAP expression. Additionally, we identified m6A-modified circRNAs modulated by Btz treatment, including circHIPK3, which is implicated in protein folding and oxidative stress regulation. These results highlight the intricate molecular networks involved in oxidative and ER stress induction in AML cells following proteotoxic stress response, laying the groundwork for future therapeutic strategies targeting these pathways.

YTHDF2 favors protumoral macrophage polarization and implies poor survival outcomes in triple negative breast cancer

Patients with triple-negative breast cancer (TNBC) frequently experience resistance to chemotherapy, leading to recurrence. The approach of optimizing anti-tumoral immunological effect is promising in overcoming such resistance, given the heterogeneity and lack of biomarkers in TNBC. In this study, we focused on YTHDF2, an N6-methyladenosine (m6A) RNA-reader protein, in macrophages, one of the most abundant intra-tumoral immune cells. Using single-cell sequencing and ex vivo experiments, we discovered that YTHDF2 significantly promotes pro-tumoral phenotype polarization of macrophages and is closely associated with down-regulated antigen-presentation signaling to other immune cells in TNBC. The in vitro deprivation of YTHDF2 favors anti-tumoral effect. Expressions of multiple transcription factors, especially SPI1, were consistently observed in YTHDF2-high macrophages, providing potential therapeutic targets for new strategies. In conclusion, YTHDF2 in macrophages appears to promote pro-tumoral effects while suppressing immune activity, indicating the treatment targeting YTHDF2 or its transcription factors could be a promising strategy for chemoresistant TNBC.

N6-methyladenosine-dependent signaling in colorectal cancer: Functions and clinical potential

Colorectal cancer (CRC) ranks as the third most prevalent malignancy worldwide. Despite the gradual expansion of therapeutic options for CRC, its clinical management remains a formidable challenge. And, because of the current dearth of technical means for early CRC screening, most patients are diagnosed at an advanced stage. Therefore, it is imperative to develop novel diagnostic and therapeutic tools for this disease. N6-methyladenosine (m6A), the predominant RNA modification in eukaryotes, can be recognized by m6A-specific methylated reading proteins to modulate gene expression. Studies have revealed that CRC disrupts m6A homeostasis through various mechanisms, thereby sustaining aberrant signal transduction and promoting its own progression. Consequently, m6A-based diagnostic and therapeutic strategies have garnered widespread attention. Although utilizing m6A as a biomarker and drug target has demonstrated promising feasibility, existing observations primarily stem from preclinical models; henceforth necessitating further investigation and resolution of numerous outstanding issues.

Demethylases in tumors and the tumor microenvironment: Key modifiers of N6-methyladenosine methylation

RNA methylation modifications are widespread in eukaryotes and prokaryotes, with N6-methyladenosine (m6A) the most common among them. Demethylases, including Fat mass and obesity associated gene (FTO) and AlkB homolog 5 (ALKBH5), are important in maintaining the balance between RNA methylation and demethylation. Recent studies have clearly shown that demethylases affect the biological functions of tumors by regulating their m6A levels. However, their effects are complicated, and even opposite results have appeared in different articles. Here, we summarize the complex regulatory networks of demethylases, including the most important and common pathways, to clarify the role of demethylases in tumors. In addition, we describe the relationships between demethylases and the tumor microenvironment, and introduce their regulatory mechanisms. Finally, we discuss evaluation of demethylases for tumor diagnosis and prognosis, as well as the clinical application of demethylase inhibitors, providing a strong basis for their large-scale clinical application in the future.

Nicotine-derived NNK promotes CRC progression through activating TMUB1/AKT pathway in METTL14/YTHDF2-mediated m6A manner

Cigarette smoking substantially promotes tumorigenesis and progression of colorectal cancer; however, the underlying molecular mechanism remains unclear. Among 662 colorectal cancer patients, our investigation revealed a significant correlation between cigarette smoking and factors, such as large tumor size, poor differentiation, and high degree of invasion. Among the nicotine-derived nitrosamines, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) emerged as the most critical carcinogen, which significantly promoted the malignant progression of colorectal cancer both in vivo and in vitro. The results of methylated RNA immunoprecipitation and transcriptome sequencing indicated that NNK upregulated transmembrane and ubiquitin-like domain-containing protein 1 (TMUB1) via N6-adenosine methylation, which was regulated by methyltransferase-like 14 (METTL14) and YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Elevated TMUB1 levels were associated with a higher risk of cancer invasion and metastasis, leading to a high mortality risk in patients with colorectal cancer. Additionally, TMUB1 promoted lysine63-linked ubiquitination of AKT by interacting with AMFR, which led to the induction of malignant proliferation and metastasis in colorectal cancer cells exposed to NNK. In summary, this study provides a new insight, indicating that targeting TMUB1 expression via METTL14/YTHDF2 mediated N6-adenosine methylation may be a potential therapeutic and prognostic target for patients with colorectal cancer who smoke.

FTO-mediated ZNF687 accelerates tumor growth, metastasis, and angiogenesis in colorectal cancer through the Wnt/β-catenin pathway

Colorectal cancer (CRC) is a common and lethal cancer. ZNF687 has been disclosed to take part in diversified cancers' progression by serving as a facilitator. However, the detailed regulatory functions of ZNF687 in the CRC have not been investigated. This work is planned to probe the impacts of ZNF687 on CRC progression. The IHC, RT-qPCR, and western blot assays were used to examine mRNA and protein gene expressions. The cell proliferation measurement was accompanied by a CCK-8 assay. The Transwell assay was performed to evaluate cell invasion and migration. The angiogenesis ability was evaluated by a tube formation experiment. The m6A level was evaluated through MeRIP and m6A dot blot assays. The binding ability between ZNF687 and FTO (fat mass and obesity associated protein) was tested through an RIP assay. The β-catenin nuclear translocation was assessed through an immunofluorescence assay. The tumor growth was evaluated through an in vivo assay. ZNF687 exhibited higher expression in CRC cells and resulted in a poor prognosis. Additionally, ZNF687 inhibition suppressed CRC cell proliferation, invasion, migration, and angiogenesis. Furthermore, the suppression of ZNF687 retarded the Wnt pathway. Through rescue assays, the reduced cell migration, proliferation, invasion, and angiogenesis mediated by ZNF687 knockdown could be reversed after BML-284 (the activator of the Wnt pathway) treatment. Finally, it was explained that ZNF687 knockdown inhibited in vivo tumor growth. This study manifested that FTO-mediated ZNF687 aggravated tumor growth, metastasis, and angiogenesis of CRC through Wnt/β-catenin pathway. This finding may provide a hopeful molecular target for CRC treatment.

N6-methyladenosine demethyltransferase FTO mediated m6A modification of estrogen receptor alpha in non-small cell lung cancer tumorigenesis

Fat mass and obesity-associated protein (FTO), which is closely linked with obesity and dietary intake, plays an important role in diet-related metabolic diseases. However, the underlying mechanism of the N6-methyladenosine (m6A) demethyltransferase FTO in tumor development and progression remains largely unexplored. Here, we demonstrated that FTO expression was largely lower in non-small cell lung cancer (NSCLC) samples than in adjacent healthy tissues, and its expression negatively correlated with poor prognosis. Gain- and loss-of-function assays revealed that FTO inhibited NSCLC tumor cell growth and metastasis in vitro and in vivo. Mechanistically, estrogen receptor alpha (ESR1) is a target of FTO, and increased FTO expression significantly impaired the m6A levels of ESR1 mRNA. There were two clear m6A modification sites (5247A and 5409A) in the 3' untranslated region (3'UTR) of ESR1, and FTO could decrease their methylation. Moreover, the m6A readers YTHDF1 and IGF2BP3 recognized and bound the m6A sites in ESR1 mRNA, thereby enhancing its stability and facilitating tumor growth. We also showed that ESR1 has good diagnostic value for NSCLC. In conclusion, we uncovered an important mechanism of epitranscriptomic regulation by the FTO-YTHDF1-IGF2BP3-ESR1 axis and identified the potential of m6A-dependent therapeutic strategies for NSCLC.

Transcriptome-wide profiling identifies colon cancer-associated m6A transcripts and potential RNA methyl modifiers

BACKGROUND

N6-methyladenosine (m6A) is a prevalent and crucial RNA methylation modification that plays a significant role in various biological and pathological processes. The dysregulation of m6A has been linked to the initiation, progression, and metastasis of several cancer types, including colon cancer. The transcriptome of colon cancer indeed provides insight into dysregulated coding and non-coding RNAs, but it does not reveal the mechanisms, such as m6A modifications, that determine post-transcriptional and pre-translational regulations. This study using MeRIP sequencing aims to explain the distribution of m6A modification across altered gene expression and its association with colon cancer.

METHODS AND RESULTS

The levels of m6A in different colon cancer cell lines were quantified and correlated with the expression of m6A modifiers such as writers, readers, and erasers. Our results showed that global m6A levels in colon cancer were associated with METTL14, YTHDF2, and YTHDC1. We performed Epi-transcriptome profiling of m6A in colon cancer cell lines using Methylated RNA Immunoprecipitation (MeRIP) sequencing. The differential methylation analysis revealed 7312 m6A regions among the colon cancer cell lines. Our findings indicated that the m6A RNA methylation modifications were mainly distributed in the last exonic and 3' untranslated regions. We also discovered that non-coding RNAs such as miRNA, lncRNA, and circRNA carry m6A marks. Gene set enrichment and motif analysis suggested a strong association of m6A with post-transcriptional events, particularly splicing control. Overall, our study sheds light on the potential role of m6A in colon cancer and highlights the importance of further investigation in this area.

CONCLUSION

This study reports m6A enrichment in the last exonic regions and 3' UTRs of mRNA transcripts in colon cancer. METTL14, YTHDF2, and YTHDC1 were the most significant modifiers in colon cancer cells. The functions of m6A-modified genes were found to be RNA methylation and RNA capping. Overall, the study illustrates the transcriptome-wide distribution of m6A and its eminent role in mRNA splicing and translation control of colon cancer.

Targeting key RNA methylation enzymes to improve the outcome of colorectal cancer chemotherapy (Review)

RNA methylation modifications are closely linked to tumor development, migration, invasion and responses to various therapies. Recent studies have shown notable advancements regarding the roles of RNA methylation in tumor immunotherapy, the tumor microenvironment and metabolic reprogramming. However, research on the association between tumor chemoresistance and N6‑methyladenosine (m6A) methyltransferases in specific cancer types is still scarce. Colorectal cancer (CRC) is among the most common gastrointestinal cancers worldwide. Conventional chemotherapy remains the predominant treatment modality for CRC and chemotherapy resistance is the primary cause of treatment failure. The expression levels of m6A methyltransferases, including methyltransferase‑like 3 (METTL3), METTL14 and METTL16, in CRC tissue samples are associated with patients' clinical outcomes and chemotherapy efficacy. Natural pharmaceutical ingredients, such as quercetin, have the potential to act as METTL3 inhibitors to combat chemotherapy resistance in patients with CRC. The present review discussed the various roles of different types of key RNA methylation enzymes in the development of CRC, focusing on the mechanisms associated with chemotherapy resistance. The progress in the development of certain inhibitors is also listed. The potential of using natural remedies to develop antitumor medications that target m6A methylation is also outlined.

The roles of m6A methylation in cervical cancer: functions, molecular mechanisms, and clinical applications

Cervical cancer (CC) is a gynecological neoplasm with the highest incidence rate, primarily attributed to the persistent infection of high-risk Human papillomavirus (HPV). Despite extensive research, the pathogenesis of CC remains unclear. N6-methyladenosine (m6A) methylation, the most prevalent form of epigenetic modification in RNA, is intricately linked to cell proliferation, metastasis, metabolism, and therapeutic resistance within the tumor microenvironment (TME) of CC. The involvement of the writer, reader, and eraser in m6A modification impacts the advancement of tumors through the regulation of RNA stability, nuclear export, translation efficiency, and RNA degradation. Here, we discuss the biogenesis of m6A, the atypical expressions of m6A regulators, the mechanisms of molecular interactions, and their functions in CC. Furthermore, we elucidate m6A modification of non-coding RNA. In the context of precision medicine, and with the advancements of genomics, proteomics, and high-throughput sequencing technologies, we summarize the application of m6A in the clinical diagnosis and treatment of CC. Additionally, new perspectives on detection methods, immune regulation, and nano-drug development are presented, which lay the foundation for further research of m6A and provide new ideas for the clinical treatment of CC.

Dermatan Sulfate/Chitosan Nanoparticles Loaded with an Anti-Inflammatory Peptide Increase the Response of Human Colorectal Cancer Cells to 5-Fluorouracil

The gold standard drug for colorectal cancer (CRC) treatment, 5-Fluorouracil (5-FU), induces pharmacological tolerance in long-term management. The transcriptional factor nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) plays a key role in 5-FU resistance. The aim of this work is to study the capability of polyelectrolytes complex nanoparticles of dermatan sulfate (DS) and chitosan (CS), loaded with the anti-inflammatory tripeptide IRW, to sensitize colorectal cancer cells to 5-FU. Fluorescence and flow cytometry studies confirmed the recognition by the nanoformulation, of the cluster of differentiation 44 (CD44) receptor, involved in the initiation and progression of colorectal tumors. Dynamic light scattering (DLS) and flow cytometry reinforced the importance of DS and CD44 receptor in the interaction, as the addition of DS or anti-CD44 antibody blocked the binding. Moreover, the nanoformulation also interacts with 3D colon cancer cultures, namely colonospheres, enriched in cancer stem cells (CSC), subpopulation responsible for drug resistance and metastasis. To evaluate the consequences of this interaction, the subcellular distribution of the transcriptional factor NFκB, is determined by immunofluorescence analysis. Internalization and the intracellular release of IRW inhibited nuclear translocation of NFκB and increased cellular sensitivity to 5-FU. Altogether, the nanoformulation could provide a selective delivery platform for IRW distribution to colorectal tumors, being an innovative strategy toward overcoming 5-FU resistance in CRC therapy.

m6A eraser FTO impairs gemcitabine resistance in pancreatic cancer through influencing NEDD4 mRNA stability by regulating the PTEN/PI3K/AKT pathway

BACKGROUND

Gemcitabine resistance has brought great challenges to the treatment of pancreatic cancer. The N6-methyladenosine (m6A) mutation has been shown to have a significant regulatory role in chemosensitivity; however, it is not apparent whether gemcitabine resistance can be regulated by fat mass and obesity-associated protein (FTO).

METHODS

Cells with established gemcitabine resistance and tissues from pancreatic cancer patients were used to evaluate FTO expression. The biological mechanisms of the effects of FTO on gemcitabine resistant cells were investigated using CCK-8, colony formation assay, flow cytometry, and inhibitory concentration 50. Immunoprecipitation/mass spectrometry, MeRIP-seq, RNA sequencing and RIP assays, RNA stability, luciferase reporter, and RNA pull down assays were employed to examine the mechanism of FTO affecting gemcitabine resistant pancreatic cancer cells.

RESULTS

The results revealed that FTO was substantially expressed in cells and tissues that were resistant to gemcitabine. Functionally, the gemcitabine resistance of pancreatic cancer could be enhanced by FTO, while its depletion inhibited the growth of gemcitabine resistant tumor cells in vivo. Immunoprecipitation/mass spectrometry showed that the FTO protein can be bound to USP7 and deubiquitinated by USP7, leading to the upregulation of FTO. At the same time, FTO knockdown significantly decreased the expression level of NEDD4 in an m6A-dependent manner. RNA pull down and RNA immunoprecipitation verified YTHDF2 as the reader of NEDD4, which promoted the chemoresistance of gemcitabine resistant cells. FTO knockdown markedly increased the PTEN expression level in an NEDD4-dependent manner and influenced the chemosensitivity to gemcitabine through the PI3K/AKT pathway in pancreatic cancer cells.

CONCLUSION

In conclusion, we found that gemcitabine resistance in pancreatic cancer can be influenced by FTO that demethylates NEDD4 RNA in a m6A-dependent manner, which then influences the PTEN expression level and thereby affects the PI3K/AKT pathway. We also identified that the FTO level can be upregulated by USP7.

The role of m6A demethylase FTO in chemotherapy resistance mediating acute myeloid leukemia relapse

Acute myeloid leukemia (AML) is the most common hematopoietic malignancies, and chemotherapy resistance is one of the main causes of relapse. Because of lower survival rate for patients with relapse, it is pivotal to identify etiological factors responsible for chemo-resistance. In this work, direct MeRIP-seq analysis of sequential samples at stage of complete remission (CR) and relapse identifies that dysregulated N6-methyladenosine (m⁶A) methylation is involved in this progression, and hypomethylated RNAs are related to cell differentiation. m⁶A demethylase FTO is overexpressed in relapse samples, which enhances the drug resistance of AML cells in vivo and in vitro. In addition, FTO knockdown cells exhibit stronger capacity of differentiation towards granules and myeloid lineages after cytosine arabinoside (Ara-C) treatment. Mechanistically, FOXO3 is identified as a downstream target of FTO, the hypomethylation of FOXO3 mRNA affects its RNA degradation and further reduces its own expression, which ultimately result in attenuated cell differentiation. Collectively, these results demonstrate that FTO-m⁶A-FOXO3 is the main regulatory axis to affect the chemotherapy resistance of AML cells and FTO is a potential therapeutic target of chemotherapy resistance in AML.

Targeting the p53 signaling pathway in cancers: Molecular mechanisms and clinical studies

Tumor suppressor p53 can transcriptionally activate downstream genes in response to stress, and then regulate the cell cycle, DNA repair, metabolism, angiogenesis, apoptosis, and other biological responses. p53 has seven functional domains and 12 splice isoforms, and different domains and subtypes play different roles. The activation and inactivation of p53 are finely regulated and are associated with phosphorylation/acetylation modification and ubiquitination modification, respectively. Abnormal activation of p53 is closely related to the occurrence and development of cancer. While targeted therapy of the p53 signaling pathway is still in its early stages and only a few drugs or treatments have entered clinical trials, the development of new drugs and ongoing clinical trials are expected to lead to the widespread use of p53 signaling-targeted therapy in cancer treatment in the future. TRIAP1 is a novel p53 downstream inhibitor of apoptosis. TRIAP1 is the homolog of yeast mitochondrial intermembrane protein MDM35, which can play a tumor-promoting role by blocking the mitochondria-dependent apoptosis pathway. This work provides a systematic overview of recent basic research and clinical progress in the p53 signaling pathway and proposes that TRIAP1 is an important therapeutic target downstream of p53 signaling.

METTL14 Facilitates the Metastasis of Pancreatic Carcinoma by Stabilizing LINC00941 in an m6A-IGF2BP2-Dependent Manner

Pancreatic adenocarcinoma (PC), one of the most fatal diseases, usually generates a poor prognosis in advanced stages. N6-methyladenosine modification has emerged as a crucial participant in tumor development and recurrence. Methyltransferase-like 14 (METTL14), as a core member of methyltransferases, is involved in tumor progression and metastasis. However, the potential mechanism by which METTL14 regulates long noncoding RNAs (lncRNAs) in PC remains unclear. RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation quantitative PCR (MeRIP-qPCR), and fluorescence in situ hybridization (FISH) were used to explore the underlying mechanisms. In our study, we found that METTL14 expression was upregulated in PC patients, and was associated with poor prognosis. In vitro and in vivo experiments, knocking down METTL14 suppressed tumor metastasis. RNA-seq and bioinformatics analyses were used to identify LINC00941 as the downstream target of METTL14. Mechanistically, LINC00941 was upregulated by METTL14 in an m6A-dependent way. LINC00941 was recruited and recognized by IGF2BP2. METTL14 enhanced the affinity of IGF2BP2 for LINC00941, while IGF2BP2 promoted the stabilization of LINC00941, which contributed to the migration and invasion of PC cells. Overall, our research revealed that METTL14 promoted the metastasis of PC through m6A modification of LINC00941. Targeting the METTL14-LINC00941-IGF2BP2 axis may provide promising therapeutic approaches for PC.

Roles of RNA Methylations in Cancer Progression, Autophagy, and Anticancer Drug Resistance

RNA methylations play critical roles in RNA processes, including RNA splicing, nuclear export, nonsense-mediated RNA decay, and translation. Regulators of RNA methylations have been shown to be differentially expressed between tumor tissues/cancer cells and adjacent tissues/normal cells. N6-methyladenosine (m6A) is the most prevalent internal modification of RNAs in eukaryotes. m6A regulators include m6A writers, m6A demethylases, and m6A binding proteins. Since m6A regulators play important roles in regulating the expression of oncogenes and tumor suppressor genes, targeting m6A regulators can be a strategy for developing anticancer drugs. Anticancer drugs targeting m6A regulators are in clinical trials. m6A regulator-targeting drugs could enhance the anticancer effects of current chemotherapy drugs. This review summarizes the roles of m6A regulators in cancer initiation and progression, autophagy, and anticancer drug resistance. The review also discusses the relationship between autophagy and anticancer drug resistance, the effect of high levels of m6A on autophagy and the potential values of m6A regulators as diagnostic markers and anticancer therapeutic targets.

m6A modification: a new avenue for anti-cancer therapy

To date, over 170 different kinds of chemical modifications on RNAs have been identified, some of which are involved in multiple aspects of RNA fate, ranging from RNA processing, nuclear export, translation, and RNA decay. m6A, also known as N 6-methyladenosine, is a prominent internal RNA modification that is catalyzed primarily by the METTL3-METTL14-WTAP methyltransferase complex in higher eukaryotic mRNA and long noncoding RNA (lncRNA). In recent years, abnormal m6A modification has been linked to the occurrence, development, progression, and prognosis of the majority of cancers. In this review, we provide an update on the most recent m6A modification discoveries as well as the critical roles of m6A modification in cancer development and progression. We summarize the mechanisms of m6A involvement in cancer and list potential cancer therapy inhibitors that target m6A regulators such as "writer" METTL3 and "eraser" FTO.

Targeting fat mass and obesity-associated protein mitigates human colorectal cancer growth in vitro and in a murine model

Introduction

Colorectal cancer (CRC) remains a significant cause of cancer related mortality. Fat mass and obesity-associated protein (FTO) is a m6A mRNA demethylase that plays an oncogenic role in various malignancies. In this study we evaluated the role of FTO in CRC tumorigenesis.

Methods

Cell proliferation assays were conducted in 6 CRC cell lines with the FTO inhibitor CS1 (50-3200 nM) (± 5-FU 5-80 mM) and after lentivirus mediated FTO knockdown. Cell cycle and apoptosis assays were conducted in HCT116 cells (24 h and 48 h, 290 nM CS1). Western blot and m6A dot plot assays were performed to assess CS1 inhibition of cell cycle proteins and FTO demethylase activity. Migration and invasion assays of shFTO cells and CS1 treated cells were performed. An in vivo heterotopic model of HCT116 cells treated with CS1 or with FTO knockdown cells was performed. RNA-seq was performed on shFTO cells to assess which molecular and metabolic pathways were impacted. RT-PCR was conducted on select genes down-regulated by FTO knockdown.

Results

We found that the FTO inhibitor, CS1 suppressed CRC cell proliferation in 6 colorectal cancer cell lines and in the 5-Fluorouracil resistant cell line (HCT116-5FUR). CS1 induced cell cycle arrest in the G2/M phase by down regulation of CDC25C and promoted apoptosis of HCT116 cells. CS1 suppressed in vivo tumor growth in the HCT116 heterotopic model (p< 0.05). Lentivirus knockdown of FTO in HCT116 cells (shFTO) mitigated in vivo tumor proliferation and in vitro demethylase activity, cell growth, migration and invasion compared to shScr controls (p< 0.01). RNA-seq of shFTO cells compared to shScr demonstrated down-regulation of pathways related to oxidative phosphorylation, MYC and Akt/ mTOR signaling pathways.

Discussion

Further work exploring the targeted pathways will elucidate precise downstream mechanisms that can potentially translate these findings to clinical trials.

m6A modification on the fate of colorectal cancer: functions and mechanisms of cell proliferation and tumorigenesis

N6-methyladenosine (m6A) is the most pervasive RNA modification in eukaryotic cells. The dynamic and reversible m6A modification of RNA plays a critical role in the occurrence and progression of tumors by regulating RNA metabolism, including translocation, mRNA stability or decay, pre-mRNA splicing, and lncRNA processing. Numerous studies have shown that m6A modification is involved in the development of various cancers. This review aims to summarize the significant role of m6A modification in the proliferation and tumorigenesis of CRC, as well as the potential of modulating m6A modification for tumor treatment. These findings may offer new therapeutic strategies for clinical implementation of m6A modification in CRC in the near future.