YTHDF2 inhibition potentiates radiotherapy antitumor efficacy

Pushing the boundaries of radiotherapy-immunotherapy combinations: highlights from the 7th immunorad conference

Over the last decade, the annual Immunorad Conference, held under the joint auspicies of Gustave Roussy (Villejuif, France) and the Weill Cornell Medical College (New-York, USA) has aimed at exploring the latest advancements in the fields of tumor immunology and radiotherapy-immunotherapy combinations for the treatment of cancer. Gathering medical oncologists, radiation oncologists, physicians and researchers with esteemed expertise in these fields, the Immunorad Conference bridges the gap between preclinical outcomes and clinical opportunities. Thus, it paves a promising way toward optimizing radiotherapy-immunotherapy combinations and, from a broader perspective, improving therapeutic strategies for patients with cancer. Herein, we report on the topics developed by key-opinion leaders during the 7th Immunorad Conference held in Paris-Les Cordeliers (France) from September 27th to 29th 2023, and set the stage for the 8th edition of Immunorad which will be held at Weill Cornell Medical College (New-York, USA) in October 2024.

Emerging importance of m6A modification in liver cancer and its potential therapeutic role

Liver cancer refers to malignant tumors that form in the liver and is usually divided into several types, the most common of which is hepatocellular carcinoma (HCC), which originates in liver cells. Other rare types of liver cancer include intrahepatic cholangiocarcinoma (iCCA). m6A modification is a chemical modification of RNA that usually manifests as the addition of a methyl group to adenine in the RNA molecule to form N6-methyladenosine. This modification exerts a critical role in various biological processes by regulating the metabolism of RNA, affecting gene expression. Recent studies have shown that m6A modification is closely related to the occurrence and development of liver cancer, and m6A regulators can further participate in the pathogenesis of liver cancer by regulating the expression of key genes and the function of specific cells. In this review, we provided an overview of the latest advances in m6A modification in liver cancer research and explored in detail the specific functions of different m6A regulators. Meanwhile, we deeply analyzed the mechanisms and roles of m6A modification in liver cancer, aiming to provide novel insights and references for the search for potential therapeutic targets. Finally, we discussed the prospects and challenges of targeting m6A regulators in liver cancer therapy.

Interactions between radiotherapy resistance mechanisms and the tumor microenvironment

BACKGROUND

Resistance to radiotherapy (RT) presents a significant clinical challenge in management of cancer. Recent evidence points to specific mechanisms of resistance within the tumor microenvironment (TME), which we aim to discuss, with the aim of overcoming the clinical challenge.

METHODS

We performed the narrative review using PubMed and Web of Science databases to identify studies that reported the regulative network and treatments of RT resistance from TME perspectives.

RESULTS

RT significantly changes the immune TME of cancers, which is closely appearing to play a key role in RT resistance (RTR) by modulating immune cell infiltration and function. Various phenotypes are involved in the development of RTR, such as autophagy, senescence, oxidative stress, cell polarization, ceramide metabolism, and angiogenesis in the TME. Key genes and pathways are also implicated in RTR, including immune and inflammatory cytokines, TGF-β, P53, the NF-κB pathway, the cGAS/STING pathway, the ERK and AKT pathway, and the STAT pathway. Based on the mechanism of RTR in the TME, many proposed routes to overcome RTR, several specifically target the TME including targeting fibroblast activation protein, exosomes management, nanomedicine, and immunotherapy. Many challenges in RT resistance still need to be further explored with emerging investigative methods, such as artificial intelligence, genetic technologies, and bioengineering.

CONCLUSIONS

The complex interactions between RT and TME significantly affect the efficiency of RT. Novel approaches to overcome this clinical difficulty are promising, which needs future work to further explore and identify better treatment strategies.

H3K18 lactylation-mediated Ythdf2 activation restrains mouse female germline stem cell proliferation via promoting Ets1 mRNA degradation

BACKGROUND

Germline stem cells are critical for sustaining fertility by balancing self-renewal and differentiation, and are regulated by genetic and epigenetic programs. Although extensively investigated, the rare female germline stem cells (FGSCs) in mammalian ovaries hinder their application in regenerative medicine. The N6-methyladenosine (m6A) reader YTHDF2 is required for female germ cell competence. However, the mechanistic underpinnings of how YTHDF2 regulates FGSC proliferation remain elusive.

RESULTS

Here, we show that knockout of Ythdf2 enhances FGSC proliferation in vitro. YTHDF2 binds m6A-modified Ets1 mRNA and facilitates its degradation in an m6A-dependent manner. ETS1 functions as a key downstream effector of YTHDF2, as suppression of ETS1 expression partially reverses the Ythdf2-KO-induced phenotype. Additionally, we demonstrate that YTHDF2/ETS1 axis participates in regulating FGSC proliferation by modulation of proliferation-related gene expression. Moreover, histone lactylation modification H3K18la activates the expression of YTHDF2 in FGSCs.

CONCLUSIONS

Overall, our study reveals that YTHDF2 intrinsically restrains mouse FGSC proliferation and provides a potential strategy to increase FGSC abundance for its potential clinical application.

Radiotherapy-induced TACC3 confers resistance of HCC to radiotherapy and enhances IL4-dependent immunosuppression to exacerbate hepatocarcinogenesis

Radiotherapy plays an increasingly crucial role in the treatment of hepatocellular carcinoma (HCC). However, resistance to radiotherapy remains a significant obstacle to achieving optimal treatment outcomes. Our objective is to elucidate the mechanisms underlying radiotherapy resistance. Through proteomic sequencing of radiotherapy-resistant cell lines and patient-derived xenograft tissues from HCC patients, we identified that Transforming Acidic Coiled-Coil Containing Protein 3 (TACC3) is upregulated in both radiotherapy-resistant cell lines and tissues. After radiotherapy treatment, DNAPK phosphorylates TACC3 at 315 threonine, leading to enhanced protein stability of TACC3. TACC3 facilitated the proliferative capacity and radiotherapy resistance of HCC cells by promoting the interaction between XRCC5 and XRCC6 through specific residues within its coiled-coil domain, namely ILE736, ASN742 and GLU773. This interaction facilitates DNA damage repair via the non-homologous end joining pathway in response to radiation, thereby contributing to the radiotherapy resistance in HCC cells. Furthermore, TACC3 increases the production of IL-4 and IL-10 within HCC cells, inducing the differentiation of M0 macrophages to M2 macrophages within the immune microenvironment, leading to the suppression of CD8+T cell cytotoxic functions and creating an immunosuppressive microenvironment in HCC. Targeting TACC3 with inhibitor KHS101 significantly inhibit the proliferation of HCC and improve the immune microenvironment of HCC.

YTHDF2: a key RNA reader and antitumor target

N6-methyladenosine (m6A) is a key mRNA modification influencing mRNA stability and translation. YTHDF2, a major m6A 'reader', was initially recognized for promoting mRNA decay but is now also known to enhance translation by binding to methylated mRNAs. YTHDF2 maintains the function of immune suppressive cells, including tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs), while also supporting cytotoxic immune cells, including natural killer (NK) and CD8+ T cells. Additionally, YTHDF2 acts as a tumor-intrinsic regulator orchestrating tumor immune evasion. Its multifaceted roles in tumor immunity make YTHDF2 a promising yet challenging therapeutic target. This review explores the complex roles and mechanisms of YTHDF2 in cancers, immune regulation, and tumor immune evasion and highlights emerging therapeutic strategies that target YTHDF2.

Impact of radiation therapy on the immunological tumor microenvironment

External beam radiation therapy (RT) is a cornerstone of modern cancer management, being utilized in both curative and palliative settings due to its safety, efficacy, and widespread availability. A primary biological effect of RT is DNA damage, which leads to significant cytostatic and cytotoxic effects. Importantly, malignant cells possess a limited capacity for DNA repair compared to normal cells, and when combined with irradiation techniques that minimize damage to healthy tissues, this creates an advantageous therapeutic window. However, the clinical effectiveness of RT also appears to involve both direct and indirect interactions between RT and non-transformed components of the tumoral ecosystem, particularly immune cells. In this review, we describe the molecular and cellular mechanisms by which irradiated cancer cells modify the immunological tumor microenvironment and how such changes ultimately impact tumor growth.

Radiation-induced amphiregulin drives tumour metastasis

The anti-tumour effect of radiotherapy beyond the treatment field-the abscopal effect-has garnered much interest1. However, the potentially deleterious effect of radiation in promoting metastasis is less well studied. Here we show that radiotherapy induces the expression of the EGFR ligand amphiregulin in tumour cells, which reprogrammes EGFR-expressing myeloid cells toward an immunosuppressive phenotype and reduces phagocytosis. This stimulates distant metastasis growth in human patients and in pre-clinical mouse tumour models. The inhibition of these tumour-promoting factors induced by radiotherapy may represent a novel therapeutic strategy to improve patient outcomes.

Attenuated Salmonella carrying IL-21 overexpression plasmid enhances radiotherapy efficacy in a preclinical model of melanoma

Melanoma, known for its aggressive behavior and tendency to metastasize to the brain and lungs, is a formidable challenge in oncology. Radiotherapy is a potent treatment for localized solid tumors, effective against both intracranial and extracranial metastases. Yet, some melanoma patients exhibit substantial resistance to radiotherapy, with the underlying mechanisms of this resistance remaining elusive. While radiotherapy can stimulate the infiltration of immune cells, thereby triggering a range of immunostimulatory effects, it can also suppress the tumor microenvironment (TME), limiting its effectiveness. In physiological conditions, cytokines inhibit the activity of immunosuppressive cells through paracrine and autocrine signaling, while also activating immune cells to boost antitumor responses. Here, we found that Interleukin (IL)-21 expression was higher in the mice with good radiotherapy response to melanoma than in the mice with poor radiotherapy response. Interestingly, we also observed the higher infiltration of M2 TAMs and lower CD8+ T cells in the group with poor radiotherapy response. To tackle this issue, we explored the therapeutic potential of a plasmid encoding IL-21, delivered via attenuated Salmonella, in mice bearing melanomas. Our findings revealed that IL-21 administration significantly reduced M2 TAMs infiltration and enhanced CD8+ T cells infiltration and granzyme B (GZMB) expression within melanoma tumors. Most importantly, the combination of IL-21 with radiotherapy led to markedly tumor reduction compared to either treatment alone. This research highlights the potential of IL-21 as a valuable adjunct to radiotherapy in the treatment of melanoma, presenting a promising strategy for enhancing antitumor immune responses and optimizing patient outcomes.

FOXA1-dependent NSUN2 facilitates the advancement of prostate cancer by preserving TRIM28 mRNA stability in a m5C-dependent manner

RNA epigenetics is gaining increased attention for its role in the initiation, metastasis, and drug resistance of tumors. These studies have primarily focused on m6A modification. However, despite being the second most abundant modification found in RNA, the role of m5C modification in prostate cancer remains largely unexplored. Here, we predict an RNA m5C methyltransferase, NSUN2, as a potential therapeutic target for prostate cancer using various bioinformatics approaches, and verify the potential of NSUN2 as a target through multiple preclinical models. Mechanistically, NSUN2 enhances the stability of TRIM28 mRNA by adding m5C modification, promoting the expression of TRIM28. Concurrently, FOXA1, a prostate cancer lineage-specific transcription factor, transcriptionally activates the expression of NSUN2. Our study confirms the clinical potential of targeting RNA epigenetics for the treatment of prostate cancer and elucidates, mechanistically, how RNA epigenetics participates in the complex biological activities within tumors via the FOXA1-NSUN2-TRIM28 axis.

Helicobacter pylori CagA elevates FTO to induce gastric cancer progression via a "hit-and-run" paradigm

BACKGROUND

Helicobacter pylori (H. pylori) infection contributes significantly to gastric cancer (GC) progression. The intrinsic mechanisms of H. pylori-host interactions and their role in promoting GC progression need further investigation. In this study, we explored the potential role of fat mass and obesity-associated protein (FTO) in mediating Cytotoxin-associated gene A (CagA)-induced GC progression.

METHODS

The effects of H. pylori infection on N6-methyladenosine (m6A) modification were evaluated in both human samples and GC cell lines. The function of FTO in the progression of GC was elucidated through in vitro and in vivo studies. A series of techniques, including methylated RNA immunoprecipitation sequencing, RNA sequencing, RNA binding protein immunoprecipitation, and chromatin immunoprecipitation assays, were utilized to investigate the mechanism by which FTO mediates the capacity of cagA-positive H. pylori to promote GC progression. Furthermore, the therapeutic potential of the FTO inhibitor meclofenamic acid (MA) in impeding GC progression was evaluated across GC cells, animal models, and human GC organoids.

RESULTS

Infection with cagA-positive H. pylori upregulated the expression of FTO, which was essential for CagA-mediated GC metastasis and significantly associated with a poor prognosis in GC patients. Mechanistically, CagA delivered by H. pylori enhanced FTO transcription via Jun proto-oncogene. Elevated FTO induced demethylation of m6A and inhibited the degradation of heparin-binding EGF-like growth factor (HBEGF), thereby facilitating the epithelial-mesenchymal transition (EMT) process in GC cells. Interestingly, eradication of H. pylori did not fully reverse the increases in FTO and HBEGF levels induced by cagA-positive H. pylori. However, treatment with a combination of antibiotics and MA substantially inhibited cagA-positive H. pylori-induced EMT and prevented GC metastasis.

CONCLUSION

Our study revealed that FTO mediates the "hit-and-run" mechanism of CagA-induced GC progression, which suggests that the therapeutic targeting of FTO could offer a promising approach to the prevention of CagA-induced cancer progression.

Identification of m6 A-regulated ferroptosis biomarkers for prognosis in laryngeal cancer

Laryngeal cancer (LC) is a malignant tumor that occurs in the larynx. N6-methyladenosine (m6A) RNA methylation, a pivotal and prevalent epigenetic modification in eukaryotic mRNA, intricately intertwines with ferroptosis, and together, they play a crucial role in the development of LC. Accordingly, further research on related molecular mechanisms and pathology of LC is necessary. Weighted gene co-expression network analysis and correlation analysis were used to identify differentially expressed m6A-related ferroptosis genes in LC. The TCGA-HNSC and GSE65858 datasets were obtained from public databases. The TCGA-HNSC dataset consisted of 110 primary tumor oropharynx samples and 12 control oropharynx samples, while the GSE65858 dataset contained forty-eight primary tumor oropharynx samples. Univariate Cox and least absolute shrinkage and selection operator (LASSO) regression were utilized for feature selection and risk model construction in the TCGA-HNSC dataset. The risk model was validated in the GSE65858 dataset. Then, a nomogram was built based on the independent prognostic factor identified using univariate and multivariate Cox regression in the TCGA-HNSC dataset. Mutation analysis, immune-related analysis, and drug sensitivity prediction were applied to analyze the utility of the risk model in the TCGA-HNSC dataset. Additionally, qRT-PCR and western blot were performed to detect the TFRC, RGS4, and FTH1 expression. Three biomarkers were identified to build a risk model using the univariate Cox and LASSO regression algorithms. Receiver operating characteristic (ROC) analysis verified the accuracy of the risk model. Tumor Immune Dysfunction and Exclusion (TIDE) and Estimation of STromal and Immune cells in MAlignant Tumors using the Expression data (ESTIMATE) algorithm showed a positive relationship between risk score and TIDE or ESTIMATE score. Furthermore, drug sensitivity prediction found that 19 chemotherapy drugs were strongly correlated with a risk score. TFRC, RGS4, and FTH1 exhibited high expression levels in 30 laryngeal carcinoma tissues and cell lines. Notably, TFRC and FTH1 expression levels were significantly associated with patient prognosis. In Conclusion, TFRC, RGS4, and FTH1, were identified as m6A-regulated ferroptosis biomarkers in LC, providing insights into LC treatment and prognosis.

Summary of the mechanism of ferroptosis regulated by m6A modification in cancer progression

The most common form of internal RNA modification in eukaryotes is called n6-methyladenosine (m6A) methylation. It has become more and more well-known as a research issue in recent years since it alters RNA metabolism and is involved in numerous biological processes. Currently, m6A alteration offers new opportunities in clinical applications and is intimately linked to carcinogenesis. Ferroptosis-a form of iron-dependent, lipid peroxidation-induced regulated cell death-was discovered. In the development of cancer, it has become an important factor. According to newly available data, ferroptosis regulates tumor growth, and cancer exhibits aberrant m6A levels in crucial ferroptosis regulatory components. On the other hand, m6A has multiple roles in the development of tumors, and the relationship between m6A-modified ferroptosis and malignancies is quite intricate. In this review, we first give a thorough review of the regulatory and functional roles of m6A methylation, focusing on the molecular processes of m6A through the regulation of ferroptosis in human cancer progression and metastasis, which are strongly associated to cancer initiation, progression, and drug resistance. Therefore, it is crucial to clarify the relationship between m6A-mediated regulation of ferroptosis in cancer progression, providing a new strategy for cancer treatment with substantial clinical implications.

Regulation and application of m6A modification in tumor immunity

The m6A modification is an RNA modification that impacts various processes of RNA molecules, including transcription, splicing, stability, and translation. Recently, researchers have discovered that the presence of m6A modification can influence the interaction between tumor cells and immune cells and also play a role in regulating the expression of immune response-related genes. Additionally, m6A modification is intricately involved in the regulation of tumor immune evasion and drug resistance. Specifically, certain tumor cells can manipulate the gene expression through m6A modification to evade immune system attacks. Therefore, it might be possible to enhance tumor immune surveillance and improve the effectiveness of immune-based therapies by manipulating m6A modification. This review systematically discusses the role of m6A modification in tumor immunity, specifically highlighting its regulation of immune cells and immune-related genes in tumor cells. Furthermore, we explore the potential of m6A modification inhibitors as anti-cancer therapies and the significance of m6A regulatory factors in predicting the efficacy of tumor immune therapy.

Targeting GOLPH3L improves glioblastoma radiotherapy by regulating STING-NLRP3-mediated tumor immune microenvironment reprogramming

Radiotherapy (RT) has been the standard-of-care treatment for patients with glioblastoma (GBM); however, the clinical effectiveness is hindered by therapeutic resistance. Here, we demonstrated that the tumor immune microenvironment (TIME) exhibited immunosuppressive properties and high expression of Golgi phosphoprotein 3 like (GOLPH3L) in RT-resistant GBM. Our study showed that GOLPH3L interacted with stimulator of interferon genes (STING) at the aspartic acid residue 184 in Golgi after RT, leading to coat protein complex II-mediated retrograde transport of STING from Golgi to endoplasmic reticulum. This suppressed the STING-NOD-like receptor thermal protein domain associated protein 3 (NLRP3)-mediated pyroptosis, resulting in suppressive TIME, driving GBM resistance to RT. Genetic GOLPH3L ablation in RT-resistant GBM cells augmented antitumor immunity and overcame tumor resistance to RT. Moreover, we have identified a small molecular inhibitor of GOLPH3L, vitamin B5 calcium (VB5), which improved the therapeutic efficacy of RT and immune checkpoint blockade by inducing a robust antitumor immune response in mouse models. Clinically, patients with GBM treated with VB5 exhibited improved responses to RT. Thus, reprogramming the TIME by targeting GOLPH3L may offer a potential opportunity to improve RT in GBM.

YTHDF2-mediated m6A modification of ONECUT2 promotes stemness and oxaliplatin resistance in gastric cancer through transcriptionally activating TFPI

AIMS

Chemoresistance results in poor outcomes of patients with gastric cancer (GC). This study aims to identify oxaliplatin resistance-related cell subpopulations in the tumor microenvironment (TME) and decipher the involved molecular mechanisms.

METHODS

Through single-cell RNA sequencing, a unique ONECUT2+TFPI+ GC cell subset was identified in the oxaliplatin-resistant TME. The functional roles and molecular mechanisms of ONECUT2 in oxaliplatin resistance were investigated in cellular and mouse models. Therapeutic efficacy of small molecule inhibitor of ONECUT2 was also evaluated.

RESULTS

The abundance of ONECUT2+TFPI+ GC cell subset was elevated in oxaliplatin-resistant GC tumors. ONECUT2 was up-regulated and associated with undesirable prognostic outcomes of patients with GC. ONECUT2 facilitated GC cell migration, stemness properties and oxaliplatin resistance. YTHDF2, an m6A "reader", was down-regulated in GC, and its overexpression facilitated ONECUT2 mRNA degradation through m6A modification. Furthermore, ONECUT2 transcriptionally activated TFPI through binding to its promoter. Small molecule inhibitor CSRM617 targeting ONECUT2 was well tolerated in GC mouse models, and could effectively improve therapeutic efficacy of oxaliplatin against GC.

CONCLUSIONS

Our study demonstrates that YTHDF2-mediated m6A modification of ONECUT2 results in stemness and oxaliplatin resistance in GC through transcriptionally activating TFPI, which provides a novel therapeutic target against oxaliplatin-resistant GC.

Proceedings of the National Cancer Institute Workshop on combining immunotherapy with radiotherapy: challenges and opportunities for clinical translation

Radiotherapy both promotes and antagonises tumour immune recognition. Some clinical studies show improved patient outcomes when immunotherapies are integrated with radiotherapy. Safe, greater than additive, clinical response to the combination is limited to a subset of patients, however, and how radiotherapy can best be combined with immunotherapies remains unclear. The National Cancer Institute-Immuno-Oncology Translational Network-Society for Immunotherapy of Cancer-American Association of Immunology Workshop on Combining Immunotherapy with Radiotherapy was convened to identify and prioritise opportunities and challenges for radiotherapy and immunotherapy combinations. Sessions examined the immune effects of radiation, barriers to anti-tumour immune response, previous clinical trial data, immunological and computational assessment of response, and next-generation radiotherapy-immunotherapy combinations. Panel recommendations included: developing and implementing patient selection and biomarker-guided approaches; applying mechanistic understanding to optimise delivery of radiotherapy and selection of immunotherapies; using rigorous preclinical models including companion animal studies; embracing data sharing and standardisation, advanced modelling, and multidisciplinary cross-institution collaboration; interrogating clinical data, including negative trials; and incorporating novel clinical endpoints and trial designs.

Targeting YTHDF2 impacts the epitranscriptome and overcomes tumor therapy resistance

Dysregulation of RNA modifiers is common across cancer types and has essential roles in tumor therapy resistance. Chen and colleagues reported that YTHDF2 played dual roles in B cell malignancies by enhancing cell proliferation and promoting immune evasion. Targeting YTHDF2 with inhibitors offers an approach to tumor treatment by regulating the epitranscriptome.

The role of YTHDF2 in anti-tumor immunity

RNA N 6-methyladenosine (m6A) modification has been identified as the most abundant RNA modification and plays crucial roles in both physiological and pathological processes. YTHDF2 was the first identified reader protein that can recognize m6A modification and recent studies also revealed its ability to bind 5-methylcytidine (m5C) modification. YTHDF2 shows a dual binding capacity to both m6A and m5C, which leads to opposite mRNA outcomes. Multiple studies have highlighted the critical roles of YTHDF2 in tumor development and tumor microenvironment. Emerging findings showed that YTHDF2 plays critical roles in immune regulation, impacting T cell, B cell, NK cell, macrophage, innate/adaptive anti-tumor immune responses, and T-cell based immunotherapy. Inhibitors have been developed to target YTHDF2, which showed potential efficacy in tumor treatment. Herein, we reviewed the molecular mechanism of YTHDF2 and its roles in tumors, immune cells, and tumor microenvironment.

m6A RNA methylation: a pivotal regulator of tumor immunity and a promising target for cancer immunotherapy

M6A modification is one of the most common regulatory mechanisms of gene expression in eukaryotic cells, influencing processes such as RNA splicing, degradation, stability, and protein translation. Studies have shown that m6A methylation is closely associated with tumorigenesis and progression, and it plays a key regulatory role in tumor immune responses. m6A modification participates in regulating the differentiation and maturation of immune cells, as well as related anti-tumor immune responses. In the tumor microenvironment, m6A modification can also affect immune cell recruitment, activation, and polarization, thereby promoting or inhibiting tumor cell proliferation and metastasis, and reshaping the tumor immune microenvironment. In recent years, immunotherapies for tumors, such as immune checkpoint inhibitors and adoptive cell immunotherapy, have been increasingly applied in clinical settings, achieving favorable outcomes. Targeting m6A modifications to modulate the immune system, such as using small-molecule inhibitors to target dysregulated m6A regulatory factors or inducing immune cell reprogramming, can enhance anti-tumor immune responses and strengthen immune cell recognition and cytotoxicity against tumor cells. m6A modification represents a new direction in tumor immunotherapy with promising clinical potential. This review discusses the regulatory role of m6A methylation on immune cells and tumor immune responses and explores new strategies for immunotherapy.

Exploring the landscape of current in vitro and in vivo models and their relevance for targeted radionuclide theranostics

Cancer remains a leading cause of mortality globally, driving ongoing research into innovative treatment strategies. Preclinical research forms the base for developing these novel treatments, using both in vitro and in vivo model systems that are, ideally, as clinically representative as possible. Emerging as a promising approach for cancer management, targeted radionuclide theranostics (TRT) uses radiotracers to deliver (cytotoxic) radionuclides specifically to cancer cells. Since the field is relatively new, more advanced preclinical models are not yet regularly applied in TRT research. This narrative review examines the currently applied in vitro, ex vivo and in vivo models for oncological research, discusses if and how these models are now applied for TRT studies, and whether not yet applied models can be of benefit for the field. A selection of different models is discussed, ranging from in vitro two-dimensional (2D) and three-dimensional (3D) cell models, including spheroids, organoids and tissue slice cultures, to in vivo mouse cancer models, such as cellline-derived models, patient-derived xenograft models and humanized models. Each of the models has advantages and limitations for studying human cancer biology, radiopharmaceutical assessment and treatment efficacy. Overall, there is a need to apply more advanced models in TRT research that better address specific TRT phenomena, such as crossfire and abscopal effects, to enhance the clinical relevance and effectiveness of preclinical TRT evaluations.

Phenylpyrazoles as Inhibitors of the m6A RNA-Binding Protein YTHDF2

The N6-methyladenosine (m6A) modification, which is the most common RNA modification in eukaryotes, is regulated by the "writer" methyltransferases, the "reader" m6A binding proteins, and the "eraser" demethylases. m6A plays a multifunctional role in physiological and pathological processes, regulating all aspects of RNA metabolism and function, including RNA splicing, translation, transportation, and degradation. Accumulating evidence suggests that the YT521-B homology domain family 2 (YTHDF2), one of the m6A "readers," is associated with various biological processes in cancers and noncancerous disorders, impacting migration, invasion, metastasis, proliferation, apoptosis, and cell cycle. Here, we describe our work in the identification of a series of functionalized pyrazoles, such as CK-75, as new YTHDF2 inhibitors, which potentially bind to a small hydrophobic pocket on the YTH domain. Cellular evaluations revealed that the small-molecule YTHDF2 inhibitors induced cell cycle arrest, induced apoptosis, and significantly inhibited the cell viability of cancer cells. Furthermore, we evaluated the transcriptome-wide change in the global RNA-binding protein and RNA-binding patterns of CK-75 via an enhanced cross-linking and immunoprecipitation assay. Our work demonstrated the feasibility of targeting the YTH domain of YTHDF2 with small molecules. The phenylpyrazoles studied in this work provided a lead structure for the further development of small molecules targeting YTHDF2 for both biological and therapeutic applications.

The m6A revolution: transforming tumor immunity and enhancing immunotherapy outcomes

N6-methyladenosine (m6A), the most prevalent RNA modification in eukaryotes, plays a critical role in the development and progression of various diseases, including cancer, through its regulation of RNA degradation, stabilization, splicing, and cap-independent translation. Emerging evidence underscores the significant role of m6A modifications in both pro-tumorigenic and anti-tumorigenic immune responses. In this review, we provide a comprehensive overview of m6A modifications and examine the relationship between m6A regulators and cancer immune responses. Additionally, we summarize recent advances in understanding how m6A modifications influence tumor immune responses by directly modulating immune cells (e.g., dendritic cells, tumor-associated macrophages, and T cells) and indirectly affecting cancer cells via mechanisms such as cytokine and chemokine regulation, modulation of cell surface molecules, and metabolic reprogramming. Furthermore, we explore the potential synergistic effects of targeting m6A regulators in combination with immune checkpoint inhibitor (ICI) therapies. Together, this review consolidates current knowledge on the role of m6A-mediated regulation in tumor immunity, offering insights into how a deeper understanding of these modifications may identify patients who are most likely to benefit from immunotherapies.

N 6-methyladenosine reader YTHDF2 in cell state transition and antitumor immunity

Recent studies have revealed that the YTHDF family proteins bind preferentially to the N 6-methyladenosine (m6A)-modified mRNA and regulate the functions of these RNAs in different cell types. YTHDF2, the first identified m6A reader in mammals, has garnered significant attention because of its profound effect to regulate the m6A epitranscriptome in multiple biological processes. Here, we review current knowledge on the mechanisms by which YTHDF2 exerts its functions and discuss recent advances that underscore the multifaceted role of YTHDF2 in development, stem cell expansion, and immune evasion. We also highlight potential therapeutic interventions targeting the m6A/YTHDF2 axis to improve the response to current antitumor therapies.

Molecular mechanisms of m6A modifications regulating tumor radioresistance

Radiotherapy is one of the most effective treatments for malignant tumors. Radioresistance is a major factor that contributes to radiotherapy failure and poor prognosis. Recent studies have elucidated the pivotal role of aberrant N6-methyladenosine (m6A) modification, the predominant internal mRNA modification in eukaryotic cells, influences cancer progression by disrupting gene expression and other critical cellular processes. Furthermore, aberrant m6A methylation provides a substrate for tumor therapy; however, whether it regulates tumor radioresistance remains unclear. Methylated transferase (writer), demethylated transferase (eraser), and methylated recognition protein (reader) are the three essential proteins that regulate m6A modification via different mechanisms in different tumors. This review summarizes the latest research advances in m6A methylation and aims to provide novel perspectives on the advancement of regimens to overcome radioresistance and tumor invasion.

RBM15 recruits myeloid-derived suppressor cells via the m6A-IGF2BP3/CBR3-AS1/miR-409-3p/CXCL1 axis, facilitating radioresistance in non-small-cell lung cancer

BACKGROUND

Radiotherapy is commonly used for locoregionally advanced NSCLC, but radioresistance is a clinical challenge. The long non-coding RNA CBR3-AS1 mediates radioresistance in NSCLC, yet the underlying molecular mechanism is unclear. This study aims to explore whether and how N6-methyladenosine (m6A) modification regulates CBR3-AS1 expression and promotes NSCLC radioresistance.

METHODS

Integrative bioinformatics analyses were used to investigate the m6A methyltransferases that were associated with CBR3-AS1 expression and radioresistance of patients using data from The Cancer Genome Atlas of lung adenocarcinoma and squamous cell carcinoma. Clinical samples of 133 patients with NSCLC was collected to validate the correlation of the methyltransferase with radioresistance. The functional role and molecular mechanism of the methyltransferase in radioresistance was investigated through a series of in vitro experiments including m6A MeRIP-PCR, lentivirus transfection, RNA immunoprecipitation, Luciferase reporter, Colony formation, Transwell invasion, Flow cytometry, ELISA and TUNEL assay and in vivo experiments.

RESULTS

The methyltransferase RNA binding motif protein 15 (RBM15) was identified as it was significantly positively correlated with CBR3-AS1 expression and overall survival of NSCLC patients receiving radiotherapy. The clinical samples demonstrated that the high protein expression of RBM15 was significantly enriched in patients with radioresistance as well as associated with poor prognosis of patients receiving radiotherapy. In vitro, RBM15 silencing enhanced the effects of radiation on the growth and invasion inhibition, and apoptosis induction of NSCLC cells; RBM15 overexpression had the opposite effects. Mechanistically, RBM15 induced CBR3-AS1 upregulation via an m6A-IGF2BP3-dependent mechanism, inducing CXCL1 expression by sponging miR-409-3p to recruit myeloid-derived suppressor cells (MDSCs) and inhibit T cell activity. In vivo, RBM15 silencing suppressed MDSC invasiveness and enhanced CD8 + and CD4 + T cell infiltration, causing NSCLC cells to overcome radioresistance.

CONCLUSION

Our study identifies methyltransferase RBM15 as a potential therapeutic target for NSCLC radioresistance whose inhibition reverses resistance through limiting MDSC recruitment via the m6A-IGF2BP3-CBR3-AS1/miR-409-3p/CXCL1 axis.

The role and mechanism of m6A methylation in diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus, characterized by progressive deterioration of renal structure and function, which may eventually lead to end-stage kidney disease (ESKD). The N6-methyladenosine (m6A) methylation, an important modality of RNA modification, involves three classes of key regulators, writers (e.g., METTL3), erasers (e.g., FTO, ALKBH5) and readers (e.g., YTHDF2), which play important roles in DN. Writers are responsible for introducing m6A modifications on RNAs, erasers remove m6A modifications and readers recognize and bind m6A-modified RNAs to regulate RNAs functions, such as mRNA stability, translation and localization. In DN, abnormal m6A modification may promote kidney injury and proteinuria by regulating key pathways involved in multiple processes, including lipid metabolism and inflammatory response, in kidney cells such as podocytes. Therefore, an in-depth study of the role and mechanism of m6A methylation that are regulated by "writers", "erasers" and "readers" in DN is expected to provide new targets and strategies for the prevention and treatment of DN.

4-1BB agonist targeted to fibroblast activation protein α synergizes with radiotherapy to treat murine breast tumor models

BACKGROUND

Ionizing radiation (IR) is a double-edged sword for immunotherapy as it may have both immunosuppressive and immunostimulatory effects. The biological effects of IR on the tumor microenvironment (TME) are a key factor for this balance. Fibroblast activation protein (FAP) is expressed on the surface of cancer-associated fibroblasts (CAF) in many cancer types and its abundance is associated with the poor immune response to immune-checkpoint-blockade in patients. We hypothesized that IR increases FAP expression in CAFs, therefore the combination of IR with targeted immunomodulators such as an agonistic anti-FAP-4-1BBL fusion protein could enhance the immune-mediated antitumoral effects of these treatments.

METHODS

The murine transplantable TS/A tumor-cell-line co-engrafted with CAFs was used to investigate increases in FAP expression in tumors following irradiation using immunohistochemistry, real-time polymerase chain reaction (RT-PCR) and multiplex tissue immunofluorescence. One lesion of bilateral tumor-bearing mice was only locally irradiated or combined with weekly injections of the bispecific muFAP-4-1BBL fusion protein (a mouse surrogate for RG7826). Tumor sizes were followed over time and TME was assessed by flow cytometry. Selective monoclonal antibody (mAb)-mediated depletions of immune cell populations, neutralizing interferon alpha/beta receptor 1 (IFNAR-I) IFNAR and interferon (IFN)-γ mAbs and gene-modified mice (4-1BB-/-) were used to delineate the immune cell subsets and mechanisms required for efficacy. 67Ga labeled muFAP-4-1BBL tracked by SPECT-CT was used to study biodistribution. In human colorectal carcinoma samples, the inducibility of FAP expression following radiotherapy was explored by multiplex immunofluorescence.

RESULTS

Irradiation of TS/A+CAF tumors in mice showed an increase in FAP levels after local irradiation. A suboptimal radiotherapy regimen in combination with muFAP-4-1BBL attained primary tumor control and measurable abscopal effects. Immune TME landscape analyses showed post-treatment increased infiltration of activated immune cells associated with the combined radioimmunotherapy treatment. Efficacy depended on CD8+ T cells, type I IFN, IFN-γ and ability to express 4-1BB. Biodistribution studies of muFAP-4-1BBL indicated enriched tumor targeting to irradiated tumors. Human colorectal cancer samples pre and post irradiation showed enhanced FAP expression after radiotherapy.

CONCLUSION

Increased FAP expression in the TME as a result of radiotherapy can be exploited to target agonist 4-1BB immunotherapy to malignant tumor lesions using an FAP-4-1BBL antibody fusion protein.

YTHDF2 mediates the protective effects of MG53 on myocardial infarction injury via recognizing the m6A modification of MG53

INTRODUCTION

High levels of MG53 may attenuate the damage from myocardial infarction (MI). Furthermore, N6-methyl-adenosine (m6A) methylation is a mode of RNA modification that influences mRNA functions. Whether m6A modification on MG53 exerts a protective role on myocardial injury remains largely unknown.

MATERIALS AND METHODS

We established hypoxia/reoxygenation (H/R) H9c2 cell and myocardial ischemia reperfusion (I/R) rat models. MG53 expression was detected using RT-qPCR, and its m6A levels were measured using Me-RIP. The relationship between MG53 and YTHDF2 was evaluated using RNA immunoprecipitation, FISH and immunofluorescence assay, and luciferase reporter assay. MI area of rats was determined using TTC staining. Cell apoptosis was assessed by flow cytometry and TUNEL assay.

RESULTS

The m6A levels of MG53 were increased in H/R-induced H9c2 cells and the myocardium of I/R rats. Moreover, knockdown of YTHDF2 recognized the m6A modification of MG53 and enhanced MG53 stability. Overexpression of MG53 inhibited apoptosis of H/R-treated H9c2 cells, which was reversed by YTHDF2, while downregulation of MG53 m6A methylation caused by METTL3 knockdown further abrogated the effect induced by YTHDF2. Additionally, MG53 attenuated MI and apoptosis in I/R rats, which were rescued by YTHDF2.

CONCLUSION

YTHDF2 hinders the protective effect of MG53 on MI by recognizing the m6A modification of MG53.

Epitranscriptomics in the Glioma Context: A Brief Overview

Epitranscriptomics, the study of chemical modifications in RNA, has emerged as a crucial field in cellular regulation, adding another layer to the established landscape of DNA- and histone-based epigenetics. A wide range of RNA modifications, including N6-methyladenosine, pseudouridine, and inosine, have been identified across nearly all RNA species, influencing essential processes such as transcription, splicing, RNA stability, and translation. In the context of brain tumors, particularly gliomas, specific epitranscriptomic signatures have been reported to play a role in tumorigenesis. Despite growing evidence, the biological implications of various RNA modifications remain poorly understood. This review offers an examination of the main RNA modifications, the interplay between modified and unmodified molecules, how they could contribute to glioma-like phenotypes, and the therapeutic impact of targeting these mechanisms.

The N6-methyladenosine writer METTL3 promotes breast cancer progression through YTHDF2-dependent posttranscriptional silencing of GSDMD

Cell pyroptosis is a form of programmed cell death, with Gasdermin-D (GSDMD) acting as its key executor. While activating pyroptosis represents a promising therapeutic strategy for cancer, the regulatory mechanisms governing GSDMD expression during cell death remain poorly understood. In this study, we identified METTL3 as a negative regulator of GSDMD-mediated pyroptosis, with high expression in breast cancer (BC) cells. YTHDF2 was found to recognize the m6A modification of GSDMD, thereby decreasing its stability. Finally, in vivo experiments further demonstrated the inhibitory effect of the METTL3 inhibitor STM2457 on tumors. Overall, these findings suggest that inhibition of METTL3 can enhance GSDMD-mediated pyroptosis and reveal a novel regulatory mechanism governing GSDMD expression, presenting a novel strategy for cancer treatment.

Preclinical advance in nanoliposome-mediated photothermal therapy in liver cancer

Liver cancer is a highly lethal malignant tumor with a high incidence worldwide. Therefore, its treatment has long been a focus of medical research. Although traditional treatment methods such as surgery, radiotherapy, and chemotherapy have increased the survival rate of patients, their efficacy remains unsatisfactory owing to the nonspecific distribution of drugs, high toxicity, and drug resistance of tumor tissues. In recent years, the application of nanotechnology in the medical field has opened a new avenue for the treatment of liver cancer. Among these treatment methods, photothermal therapy (PTT) based on nanoliposomes has attracted wide attention owing to its unique targeting and high efficiency. This article reviews the latest preclinical research progress of nanoliposome-based PTT for liver cancer and its metastasis, discusses the preclinical challenges in this field, and proposes directions for improvement, with the aim of improving the effectiveness of liver cancer treatment.

YTHDF2 promotes ATP synthesis and immune evasion in B cell malignancies

Long-term durable remission in patients with B cell malignancies following chimeric antigen receptor (CAR)-T cell immunotherapy remains unsatisfactory, often due to antigen escape. Malignant B cell transformation and oncogenic growth relies on efficient ATP synthesis, although the underlying mechanisms remain unclear. Here, we report that YTHDF2 facilitates energy supply and antigen escape in B cell malignancies, and its overexpression alone is sufficient to cause B cell transformation and tumorigenesis. Mechanistically, YTHDF2 functions as a dual reader where it stabilizes mRNAs as a 5-methylcytosine (m5C) reader via recruiting PABPC1, thereby enhancing their expression and ATP synthesis. Concomitantly, YTHDF2 also promotes immune evasion by destabilizing other mRNAs as an N6-methyladenosine (m6A) reader. Small-molecule-mediated targeting of YTHDF2 suppresses aggressive B cell malignancies and sensitizes them to CAR-T cell therapy.

New insights into N6-methyladenosine in hepatocellular carcinoma immunotherapy

N6-methylation is a modification in which a methyl group is added to the adenine base of a nucleotide. This modification is crucial for controlling important functions that are vital for gene expression, including mRNA splicing, stability, and translation. Due to its intricate participation in both normal cellular processes and the course of disease, as well as its critical role in determining cell fate, N6-methyladenosine (m6A) alteration has recently attracted a lot of interest. The formation and progression of many diseases, especially cancer, can be attributed to dysregulated m6A alteration, which can cause disturbances in a variety of cellular functions, such as immunological responses, cell proliferation, and differentiation. In this study, we examine how m6A dysregulation affects hepatocellular carcinoma (HCC), with a particular emphasis on how it contributes to immunological evasion and carcinogenesis. We also investigate its potential as a novel therapeutic target, providing new perspectives on potential therapeutic approaches meant to enhance clinical results for patients with HCC.

The interplay between RNA m6A modification and radiation biology of cancerous and non-cancerous tissues: a narrative review

The diverse radiation types in medical treatments and the natural environment elicit complex biological effects on both cancerous and non-cancerous tissues. Radiation therapy (RT) induces oncological responses, from molecular to phenotypic alterations, while simultaneously exerting toxic effects on healthy tissue. N6-methyladenosine (m6A), a prevalent modification on coding and non-coding RNAs, is a key epigenetic mark established by a set of evolutionarily conserved enzymes. The interplay between m6A modification and radiobiology of cancerous and non-cancerous tissues merits in-depth investigation. This review summarizes the roles of m6A in the biological effects induced by ionizing radiation and ultraviolet (UV) radiation. It begins with an overview of m6A modification and its detection methods, followed by a detailed examination of how m6A dynamically regulates the sensitivity of cancerous tissues to RT, the injury response in non-cancerous tissues, and the toxicological effects of UV exposure. Notably, this review underscores the importance of novel regulatory mechanisms of m6A and their potential clinical applications in identifying epigenetically modulated radiation-associated biomarkers for cancer therapy and estimation of radiation dosages. In conclusion, enzyme-mediated m6A-modification triggers alterations in target gene expression by affecting the metabolism of the modified RNAs, thus modulating progression and radiosensitivity in cancerous tissues, as well as radiation effects on normal tissues. Several promising avenues for future research are further discussed. This review highlights the importance of m6A modification in the context of radiation biology. Targeting epi-transcriptomic molecules might potentially provide a novel strategy for enhancing the radiosensitivity of cancerous tissues and mitigating radiation-induced injury to normal tissues.

YTHDF2 contributes to psoriasis by promoting proliferation and inflammatory response through regulation of the Wnt signaling pathway

YT521-B homology domain family 2 (YTHDF2), a pivotal m6A-binding protein, is now understood to significantly influence a diverse array of biological functions, including cell migration, proliferation, differentiation, and inflammatory responses. Additionally, YTHDF2 participates in mRNA decay and pre-rRNA processing. This study explored the specific role of YTHDF2 in the pathogenesis of psoriasis and its underlying mechanisms. Our preliminary findings revealed upregulation of YTHDF2 expression in psoriasis. Subsequent silencing of YTHDF2 in a psoriatic cell model resulted in a marked decrease in mRNA expression of IL-17A, S100A8, and S100A9, accompanied by a reduction in cell proliferation. Conversely, overexpression of YTHDF2 led to the opposite effects. Treatment with DC-Y27-13, a YTHDF2 inhibitor, demonstrated a therapeutic effect in psoriasis mice. Next, mRNA sequencing analysis identified significant enrichment of differentially expressed genes within the Wnt signaling pathway. Further investigation revealed that deletion of YTHDF2 increased the half-life and expression of Dickkopf homolog 3 (DKK3), a potent inhibitor of the Wnt signaling pathway. Consequently, the inhibition of Wnt signaling attenuated the inflammatory response and inhibited cell proliferation.

"Add More Arrows to Your Quiver": The Role of Adding Another Chemotherapy Drug to Fluoropyrimidine and Long Term Radiotherapy in Locally Advanced Rectal Cancer: A Systematic Review and Meta-Analysis

Objectives: Despite optimal local control obtained with neoadjuvant chemoradiotherapy (CRT), data on overall survival (OS) and disease-free survival (DFS) of local advanced rectal cancer patients are still equivocal. This meta-analysis aimed to estimate the pathological complete response (pCR), regression rate, DFS, and OS probabilities of rectal cancer patients treated with a second chemotherapy drug added to fluoropyrimidine and long-term radiotherapy. Methods: Computerized bibliographic searches of MEDLINE, PUBMED, Web of Science and the Cochrane Central Register of Controlled Trials databases (1970-2023) were supplemented with hand searches of reference lists. Studies were included if they were randomised controlled trials (RCTs) comparing intensified chemotherapy with CRT to preoperative CRT and if they had patients with resectable, histologically proven rectal adenocarcinoma without metastases. Results: Eighteen RCTs (7695 patients) were analysed. Data on population, intervention, and outcomes were extracted from each RCT, following the intention-to-treat method, by three independent observers and combined using the DerSimonian and Laird methods. A chemotherapy with two drug and long-term radiotherapy CRT, compared to preoperative CRT (fluoropyrimidine and long-term radiotherapy), significantly increases the rate of pathological complete response (OR 1.37 (95% CI, 1.16-1.63) p = 0.0003) and the regression rate (OR 1.57 (95% CI, 1.16-2.14) p < 0.00001). Furthermore, it increases DFS (HR 0.87 (95% CI, 0.79 to 0.95) p = 0.002 and OS HR 0.84 (95% CI, 0.74 to 0.95) p = 0.007). The risk of severe adverse events (≥G3) is increased OR 1.96 (95% CI 1.35-2.85), p = 0.0005. Conclusions: In patients with resectable rectal cancer, intensified chemotherapy can reduce by 13% the risk of disease progression and by 16% the risk of death.

Inhibition of METTL14 overcomes CDK4/6 inhibitor resistance driven by METTL14-m6A-E2F1-axis in ERα-positive breast cancer

CDK4/6i, the first-line drug for treating ERα-positive breast cancer, significantly improves clinical outcomes. However, CDK4/6i resistance often develops and remains a major hurdle, and the underlying mechanisms remain challenging to fully investigate. Here, we used Genome-wide CRISPR/Cas9 library screening combined with single-cell sequencing to screen for molecules mediating CDK4/6i resistance and identified METTL14 as a determinant of CDK4/6i sensitivity. Clinical samples and datasets were analyzed and in vitro and in vivo experiments were performed to confirm the critical function of METTL14 in CDK4/6i resistance. Mechanistically, METTL14 can induce an increase in E2F1 expression in breast cancer cells via an m6A IGF2BP2-dependent mechanism and thus promote CDK4/6i resistance. Furthermore, through a small molecule screen, a novel METTL14 inhibitor named WKYMVM, which can restore sensitivity to CDK4/6i in CDK4/6i-resistant breast cancer cells, was identified. Treatment with folate-conjugated liposomes targeting breast cancer cells that contained both a CDK4/6i and WKYMVM revealed the synergistic effect of METTL14 inhibition with CDK4/6i therapy in a CDK4/6i-resistant PDX model. Together, our findings reveal the mechanism of CDK4/6i resistance and provide a strategy for overcoming CDK4/6i resistance via METTL14 inhibition.

RNA modifications in cancer

RNA modifications are emerging as critical cancer regulators that influence tumorigenesis and progression. Key modifications, such as N6-methyladenosine (m6A) and 5-methylcytosine (m5C), are implicated in various cellular processes. These modifications are regulated by proteins that write, erase, and read RNA and modulate RNA stability, splicing, translation, and degradation. Recent studies have highlighted their roles in metabolic reprogramming, signaling pathways, and cell cycle control, which are essential for tumor proliferation and survival. Despite these scientific advances, the precise mechanisms by which RNA modifications affect cancer remain inadequately understood. This review comprehensively examines the role RNA modifications play in cancer proliferation, metastasis, and programmed cell death, including apoptosis, autophagy, and ferroptosis. It explores their effects on epithelial-mesenchymal transition (EMT) and the immune microenvironment, particularly in cancer metastasis. Furthermore, RNA modifications' potential in cancer therapies, including conventional treatments, immunotherapy, and targeted therapies, is discussed. By addressing these aspects, this review aims to bridge current research gaps and underscore the therapeutic potential of targeting RNA modifications to improve cancer treatment strategies and patient outcomes.

N6-methyladenosine modification of RIMS binding protein 2 promotes head and neck squamous cell carcinoma proliferation and radiotherapy tolerance through endoplasmic reticulum stress

Insulin-like growth factor binding protein 2 (IGF2BP2) fulfills a key role in the development of head and neck squamous cell carcinoma (HNSCC). Radiotherapy is an effective method to treat HNSCC; however, radiation resistance is the main reason for treatment failure. At present, the carcinogenic role of IGF2BP2 in terms of the proliferation of HNSCC and the radioresistance of its therapy remain poorly understood. In the present study, patients with HNSCC with higher IGF2BP2 expression levels were associated with shorter survival times. IGF2BP2 is significantly upregulated in HNSCC cells compared with irradiated cell. Based on functional studies, IGF2BP2 was found to promote HNSCC cell proliferation and tolerance to radiotherapy both in vitro and in vivo. In terms of the underlying mechanism, RIMS binding protein 2 (RIMBP2) was found to be highly expressed in HNSCC and to promote the proliferation of HNSCC and radiotherapy resistance. RIMBP2 was shown to be a direct target of IGF2BP2, activating endoplasmic reticulum stress in HNSCC. In addition, it has been demonstrated that IGF2BP2, as m6A reader, is able to promote RIMBP2 stability via binding to m6A sites in the RIMBP2-coding sequence region. Therefore, the present study has unveiled a potential mechanism via which IGF2BP2 promotes HNSCC development and radiotherapy resistance; moreover, from a therapeutic perspective, IGF2BP2 may serve as a potential therapeutic target and a valuable prognostic biomarker for patients with HNSCC who have developed tolerance towards radiotherapy.

LAT4 drives temozolomide induced radiotherapy resistance in glioblastoma by enhancing mTOR pathway activation

BACKGROUND

Glioblastoma multiforme (GBM) represents the most prevalent form of primary malignant tumor within the central nervous system. The emergence of resistance to radiotherapy and chemotherapy represents a significant impediment to advancements in glioma treatment.

METHODS

We established temozolomide (TMZ)-resistant GBM cell lines by chronically exposing U87MG cell lines to TMZ, and dimethyl sulfoxide (DMSO) was used as placebo control. In vivo and in vitro experiments verified the resistance of resistant cells to chemotherapy and radiotherapy. LAT4 was identified by transcriptomics to be associated with GBM treatment resistance and relapse. The relationship between LAT4 and mTOR pathway activity was also analyzed. Finally, the effect of BCH (LAT inhibitor) combined with radiotherapy on GBM prognosis was verified in vivo.

RESULTS

We have first confirmed that TMZ not only induces resistance to chemotherapy in GBM cells but also enhances their resistance to radiotherapy, which is a significant finding in the process of building TMZ-resistant U87MG GBM cell lines. We then performed comprehensive transcriptomic analysis and identified amino acid metabolism as a potential key factor in radiotherapy resistance. Specifically, we confirmed that the upregulation of LAT4 following chemotherapy enhances leucine metabolism within tumors in vitro and in vivo, thereby modulating the mechanistic target of mTOR pathway and leading to radiotherapy resistance. Of note, the application of inhibitors targeting leucine metabolism was shown to restore the sensitivity of these cells to radiotherapy, highlighting a potential therapeutic strategy for overcoming resistance in GBM.

CONCLUSIONS

Our study links tumor sensitivity to chemotherapy and radiotherapy and highlights the critical role of LAT4 in activating the mTOR pathway and GBM radiotherapy resistance. It suggests ways to improve radiotherapy sensitivity to GBM.

m6A-Methylated NUTM2B-AS1 Promotes Hepatocellular Carcinoma Stemness Feature via Epigenetically Activating BMPR1A Transcription

Purpose

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies in the world. Oncofetal proteins are the optimal diagnostic biomarkers and therapeutic targets for HCC. As the most abundant modification in RNA, N6-methyladenosine (m6A) has been reported to be involved in HCC initiation and progression. However, whether m6A has oncofetal characteristics remains unknown.

Methods

Gene expression in HCC tissues and cells was detected using qPCR. The level of m6A methylation was determined using methylated RNA immunoprecipitation assay. The biological roles of NUTM2B-AS1 in HCC were detected using Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine incorporation, and spheroid formation assays. The mechanisms underlying the roles of NUTM2B-AS1 were explored using RNA immunoprecipitation (RIP), chromatin isolation by RNA purification (ChIRP), chromatin immunoprecipitation (ChIP), and assay for transposase-accessible chromatin (ATAC).

Results

NUTM2B-AS1 was identified as a novel oncofetal long noncoding RNA that was upregulated in the fetal liver and HCC and silenced in adult liver tissues. METTL3 and METTL16 induce m6A hypermethylation of NUTM2B-AS1. The m6A methylation levels of NUTM2B-AS1 exhibit oncofetal characteristics. m6A methylation upregulates NUTM2B-AS1 expression by increasing NUTM2B-AS1 transcript stability. m6A-methylated NUTM2B-AS1 promotes HCC cell proliferation and stemness via epigenetically activating BMPR1A expression. NUTM2B-AS1 specifically binds to BMPR1A promoter. m6A-methylated NUTM2B-AS1 is recognized by the m6A reader YTHDC2, which further binds to the H3K4 methyltransferase MLL1. m6A-methylated NUTM2B-AS1 recruits YTHDC2 and MLL1 to BMPR1A promoter, leading to increased H3K4me3 and chromatin accessibility at BMPR1A promoter. Functional rescue assays suggest that BMPR1A is a critical mediator of the oncogenic role of m6A-methylated NUTM2B-AS1 in HCC.

Conclusion

METTL3- and METTL16-mediated m6A methylation of NUTM2B-AS1 is a novel oncofetal molecular event in HCC that promotes HCC stemness via epigenetically activating BMPR1A transcription.

The three YTHDF paralogs and VIRMA are strong cross-histotype tumor driver candidates among m6A core genes

N6-Methyladenosine (m6A) is the most abundant internal modification in mRNAs. Despite accumulating evidence for the profound impact of m6A on cancer biology, there are conflicting reports that alterations in genes encoding the m6A machinery proteins can either promote or suppress cancer, even in the same tumor type. Using data from The Cancer Genome Atlas, we performed a pan-cancer investigation of 15 m6A core factors in nearly 10000 samples from 31 tumor types to reveal underlying cross-tumor patterns. Altered expression, largely driven by copy number variations at the chromosome arm level, results in the most common mode of dysregulation of these factors. YTHDF1, YTHDF2, YTHDF3 and VIRMA are the most frequently altered factors and the only ones to be uniquely altered when tumors are grouped according to the expression pattern of the m6A factors. These genes are also the only ones with coherent, pan-cancer predictive power for progression-free survival. On the contrary, METTL3, the most intensively studied m6A factor as a cancer target, shows much lower levels of alteration and no predictive power for patient survival. Therefore, we propose the non-enzymatic YTHDF and VIRMA genes as preferred subjects to dissect the role of m6A in cancer and as priority cancer targets.

The m6A modification of ACSL4 mRNA sensitized esophageal squamous cell carcinoma to irradiation via accelerating ferroptosis

Radioresistance is a major obstacle for the therapy of esophageal squamous cell carcinoma (ESCC) and lead to a poor prognosis. Ferroptosis is supposed to be responsible for radioresistance. However, the ferroptosis-induced radioresistance in ESCC and its related regulatory mechanisms are not yet fully understood. In this study, human ESCC cell line and the corresponding radioresistance cells were irradiated with 6 megavolts (MV) X-ray. It was showed that irradiation led to less ferroptosis in radioresistant ESCC cells as compared to the parental cells, as depicted by transmission electron microscopy, intracellular Fe2+ iron contents, lipid peroxidation, and expression of COX2. The increase of ASCL4 expression levels in radioresistant cells after radiotherapy was smaller than that in the parental cells. ACSL4 overexpression significantly enhanced ferroptosis. The fold increase in ACSL4 m6A modification in the radioresistant cells was significantly smaller than that in the parental cells as detected by methylated RNA immunoprecipitation with qRT-PCR. METTL14 overexpression accelerated ferroptosis induced by irradiation via upregulating m6A modification of ACSL4 mRNA. In conclusions, ferroptosis ablation was responsible for the radioresistant of ESCC. The METTL14-mediated m6A modification of ACSL4 mRNA sensitized ESCC to irradiation via accelerating ferroptosis. This study sheds new light on our understanding of radioresistant in ESCC, and provides potential strategies for ESCC radiotherapy.

Exploring m6A methylation in skin Cancer: Insights into molecular mechanisms and treatment

N6-methyladenosine (m6A) is the most common and prevalent internal mRNA modification in eukaryotes. m6A modification is a dynamic and reversible process regulated by methyltransferases, demethylases, and m6A binding proteins. Skin cancers, including melanoma and nonmelanoma skin cancers (NMSCs), are among the most commonly diagnosed cancers worldwide. m6A methylation is involved in the regulation of RNA splicing, translation, degradation, stability, translocation, export, and folding. Aberrant m6A modification participates in the pathophysiological processes of skin cancers and is associated with tumor cell proliferation, invasion, migration, and metastasis during cancer progression. In this review, we provide a comprehensive summary of the biological functions of m6A and the most up-to-date evidence related to m6A RNA modification in skin cancer. We also emphasize the potential clinical applications in the diagnosis and treatment of skin cancers.

YTHDF2 promotes anaplastic thyroid cancer progression by activating the DDIT4/AKT/mTOR signaling pathway

BACKGROUND

RNA methylation, an important reversible post-transcriptional modification in eukaryotes, has emerged as a prevalent epigenetic alteration. However, the role of the m6A reader YTH domain family 2 (YTHDF2) has not been reported in anaplastic thyroid cancer (ATC) and its biological mechanism is unclear.

METHODS

The relationship between YTHDF2 expression and ATC was determined using data sets and tissue samples. A range of analytical techniques were employed to investigate the regulatory mechanism of YTHDF2 in ATC, including bioinformatics analysis, m6A dot-blot analysis, methylated RNA immunoprecipitation sequencing (MeRIP-seq), RNA immunoprecipitation (RIP) assays, RNA sequencing, RNA stability assays and dual luciferase reporter gene assays. In vitro and in vivo assays were also conducted to determine the contribution of YTHDF2 to ATC development.

RESULTS

YTHDF2 expression was significantly increased in ATC. The comprehensive in vitro and in vivo experiments demonstrated that YTHDF2 knockdown significantly attenuated ATC proliferation, invasion, migration, and apoptosis promotion, whereas YTHDF2 overexpression yielded the opposite trend. Mechanistically, RNA-seq, MeRIP-seq and RIP-seq analysis, and molecular biology experiments demonstrated that YTHDF2 accelerated the degradation of DNA damage-inducible transcript 4 or regulated in DNA damage and development 1 (DDIT4, or REDD1) mRNA in an m6A-dependent manner, which in turn activated the AKT/mTOR signaling pathway and induced activation of epithelial-mesenchymal transition (EMT), thereby promoting ATC tumor progression.

CONCLUSIONS

This study is the first to demonstrate that elevated YTHDF2 expression levels suppress DDIT4 expression in an m6A-dependent manner and activate the AKT/mTOR signaling pathway, thereby promoting ATC progression. YTHDF2 plays a pivotal role in ATC progression, and it may serve as a promising therapeutic target in the future.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

YTHDF2 upregulation and subcellular localization dictate CD8 T cell polyfunctionality in anti-tumor immunity

RNA methylation is an important regulatory process to determine immune cell function but how it affects the anti-tumor activity of CD8 T cells is not fully understood. Here we show that the N6-methyladenosine (m6A) RNA reader YTHDF2 is highly expressed in early effector or effector-like CD8 T cells. We find that YTHDF2 facilitates nascent RNA synthesis, and m6A recognition is fundamental for this distinctively nuclear function of the protein, which also reinforces its autoregulation at the RNA level. Loss of YTHDF2 in T cells exacerbates tumor progression and confers unresponsiveness to PD-1 blockade in mice and in humans. In addition to initiating RNA decay that is necessary for mitochondrial fitness, YTHDF2 orchestrates chromatin changes that promote T cell polyfunctionality. YTHDF2 interacts with IKZF1/3, which is important for sustained transcription of their target genes. Accordingly, immunotherapy-induced efficacy could be largely restored in YTHDF2-deficient T cells through combinational use of IKZF1/3 inhibitor lenalidomide in a mouse model. Thus, YTHDF2 coordinates epi-transcriptional and transcriptional networks to potentiate T cell immunity, which could inform therapeutic intervention.

Targeted modulation of myeloid-derived suppressor cells in the tumor microenvironment: Implications for cancer therapy

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells originating from the bone marrow, known for their potent immunosuppressive functions that contribute to tumor immune evasion and progression. This paper provides a comprehensive analysis of the multifaceted interactions between MDSCs and tumors, exploring their distinct phenotypes and immunosuppressive mechanisms. Key roles of MDSCs in tumor biology are discussed, including their involvement in the formation of the pre-metastatic niche, facilitation of angiogenesis, enhancement of vascular permeability, suppression of tumor cell apoptosis, and promotion of resistance to cancer therapies. Additionally, the review highlights recent advances in the development of MDSC-targeting therapies, with a focus on their potential to enhance anti-tumor immunity. The therapeutic potential of Traditional Chinese Medicine (TCM) in modulating MDSC quantity and function is also explored, suggesting a novel approach to cancer treatment by integrating traditional and modern therapeutic strategies.