PRMT5 regulates RNA m6A demethylation for doxorubicin sensitivity in breast cancer

Dexmedetomidine inhibits ferroptosis through the Akt/GSK3β/Nrf2 axis and alleviates adriamycin-induced cardiotoxicity

The cardiotoxicity of Adriamycin(ADR) limits its clinical application, and its molecular mechanism is not very clear. At present, Dexrazoxane (DXZ) is the only approved drug to prevent ADR-induced cardiotoxicity (DIC), but it also has serious adverse reactions. Therefore, it is a key scientific challenge to find a drug with strong myocardial protection, few adverse reactions and no effect on the anti-tumor effect of ADR. In this study, we established the DIC model in rats. Cardiomyocyte hypertrophy and myocardial fibrosis increased significantly, and MDA and LDH increased significantly in serum. Dexmedetomidine (DEX) is a carbohydrate with multiple biological activities that can significantly improve the above DIC process. Echocardiography confirmed that DEX could reverse the changes of ESV, EDV, EF and FS induced by ADR. In vitro, experiments confirmed that DEX reversed the upregulation of ANP, BNP, MHC and Collagen III protein levels induced by ADR. DEX improves DIC by inhibiting ferroptosis. Erastin, a ferroptosis agonist, confirmed that DEX improved DIC by inhibiting ferroptosis. Mechanically, DEX increases the expression of Nrf2 in the nucleus through the Akt/Gsk3β signalling axis, thereby regulating ferroptosis in cardiomyocytes. In addition, DEX can improve DIC while not affecting the anti-tumor effect of ADR.

METTL3-dependent m6A modification of SNAP29 induces "autophagy-mitochondrial crisis" in the ischemic microenvironment after soft tissue transplantation

Necrosis at the ischemic distal end of flap transplants increases patients' pain and economic burden. Reactive oxygen species (ROS) and mitochondrial damage are crucial in regulating parthanatos, but the mechanisms linking disrupted macroautophagic/autophagic flux to parthanatos in ischemic flaps remain unclear. The results of western blotting, immunofluorescence staining, and a proteomic analysis revealed that the autophagic protein SNAP29 was deficient in ischemic flaps, resulting in disrupted autophagic flux, increased ROS-induced parthanatos, and aggravated ischemic flap necrosis. The use of AAV vector to restore SNAP29 in vivo mitigated the disruption of autophagic flux and parthanatos. Additionally, quantification of the total m6A level and RIP-qPCR, MeRIP-qPCR, and RNA stability assessments were performed to determine differential Snap29 mRNA m6A methylation levels and mRNA stability in ischemic flaps. Various in vitro and in vivo tests were conducted to verify the ability of METTL3-mediated m6A methylation to promote SNAP29 depletion and disrupt autophagic flux. Finally, we concluded that restoring SNAP29 by inhibiting METTL3 and YTHDF2 reversed the "autophagy-mitochondrial crisis", defined for the first time as disrupted autophagic flux, mitochondrial damage, mitochondrial protein leakage, and the occurrence of parthanatos. The reversal of this crisis ultimately promoted the survival of ischemic flaps.Abbreviations: AAV = adeno-associated virus; ACTA2/α-SMA = actin alpha 2, smooth muscle, aorta; AIFM/AIF = apoptosis-inducing factor, mitochondrion-associated; ALKBH5 = alkB homolog, RNA demythelase; Baf A1 = bafilomycin A1; CQ = chloroquine; DHE = dihydroethidium; ECs = endothelial cells; F-CHP = 5-FAM-conjugated collagen-hybridizing peptide; GO = gene ontology; HUVECs = human umbilical vein endothelial cells; KEGG = Kyoto Encyclopedia of Genes and Genomes; LC-MS/MS = liquid chromatography-tandem mass spectrometry; LDBF = laser doppler blood flow; m6A = N6-methyladenosine; MAP1LC3/LC3 = microtubule-associated protein 1 light chain 3; MeRIP = methylated RNA immunoprecipitation; METTL3 = methyltransferase 3, N6-adenosine-methyltransferase complex catalytic subunit; NAC = N-acetylcysteine; OGD = oxygen glucose deprivation; PAR = poly (ADP-ribose); PARP1 = poly (ADP-ribose) polymerase family, member 1; PECAM1/CD31 = platelet/endothelial cell adhesion molecule 1; ROS = reactive oxygen species; RT-qPCR = reverse transcription quantitative polymerase chain reaction; RIP = RNA immunoprecipitation; SNAP29 = synaptosomal-associated protein 29; SNARE = soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SQSTM1 = sequestosome 1; SRAMP = sequence-based RNA adenosine methylation site predicting; STX17 = syntaxin 17; TMT = tandem mass tag; TUNEL = terminal deoxynucleotidyl transferase dUTP nick end labeling; VAMP8 = vesicle-associated membrane protein 8; WTAP = WT1 associating protein; YTHDF2 = YTH N6-methyladenosine RNA binding protein 2; 3' UTR = 3'-untranslated region.

The expression of PRMT5 is associated with postoperative chemotherapeutic outcome in colon cancer

BACKGROUND

Postoperative chemotherapy is an essential treatment in locally advanced colon cancer, however, effective biomarkers for predicting patients who will benefit from this therapy are lacking. This study aims to explore the clinical value of protein arginine methyltransferase 5 (PRMT5) in guiding adjuvant chemotherapy in patients with colon cancer.

METHODS

PRMT5 expression was determined via immunohistochemistry (IHC) in tumor and paratumor samples from 199 colon cancer patients who underwent radical surgery. The correlation between PRMT5 expression and clinicopathological parameters, as well as clinical outcomes, was subsequently investigated.

RESULTS

The protein expression levels of PRMT5 were significantly elevated in colon cancer tissues compared to paratumor tissues (P < 0.01). However, the expression of PRMT5 in colon cancer did not show a significant association with various clinicopathological parameters, including sex, age, tumor location, histological differentiation, TNM stage, vascular invasion, or microsatellite status. Notably, a strong correlation was observed between PRMT5 expression and adjuvant therapeutic outcomes: patients with high PRMT5 expression exhibited a lower 5-year disease-free survival (DFS) rate compared to those with low PRMT5 expression within the chemotherapy group (50% vs. 67.2%, P = 0.039). In contrast, PRMT5 expression did not correlate with clinical outcomes in the non-chemotherapy group. Furthermore, multivariate analysis indicated that PRMT5 expression, along with N stage and microsatellite status, served as independent risk factors for 5-year DFS in patients undergoing adjuvant chemotherapy.

CONCLUSION

This study highlights PRMT5 as a prognostic marker for adjuvant chemotherapy in patients with colon cancer. The findings suggest that PRMT5 expression may serve as an important predictor of therapeutic outcomes, providing valuable insights for clinical decision-making and personalized treatment strategies.

ALKBH5 modulates m6A modification to enhance acute myeloid leukemia resistance to adriamycin

Acute myeloid leukemia (AML) is a fatal malignancy with rising incidence and low cure rates. This study aims to investigate the effect of alkB homolog 5 (ALKBH5)-mediated N6-methyladenosine (m6A) modification on adriamycin (ADR) resistance in AML. First, the levels of ALKBH5, taurine upregulated 1 (TUG1), YTH N6-methyladenosine RNA binding protein F2 (YTHDF2), euchromatic histone lysine methyltransferase 2 (EHMT2), and SH3 domain-binding glutamate-rich protein-like (SH3BGRL) were measured. IC50 values, cell proliferation, and apoptosis were determined. m6A levels were analyzed, and the binding interactions between TUG1 and YTHDF2, as well as TUG1 and EHMT2, were assessed. The stability of TUG1 and the enrichment of EHMT2 and H3K9me2 on the SH3BGRL promoter were confirmed. In vivo experiments were conducted to further validate the results. The findings revealed that ALKBH5 was overexpressed in both AML- and ADR-resistant cells, and silencing ALKBH5 reduced the ADR resistance of AML cells. ALKBH5 removed m6A modifications from TUG1, disrupting the interaction between YTHDF2 and TUG1, thereby stabilizing TUG1 expression. TUG1 bound to EHMT2, promoting H3K9me2 modification on the SH3BGRL promoter and suppressing SH3BGRL expression. Overexpression of TUG1 or knockdown of SH3BGRL reversed the suppressive effect of ALKBH5 knockdown on ADR resistance. In vivo, ALKBH5 knockdown inhibited ADR resistance in AML cells. In conclusion, ALKBH5 removed m6A modification to stabilize TUG1 expression in a YTHDF2-dependent manner, enhancing H3K9me2 levels on the SH3BGRL promoter and suppressing SH3BGRL expression, thus promoting ADR resistance in AML cells.

A m6A writer RBM15 enhances the cell malignancy of osteosarcoma by mediating m6A modification of lncRNA THAP9-AS1

BACKGROUND

Osteosarcoma (OS) remains a potentially fatal disease in children. Increasing evidence highlights the implication of lncRNAs and N6-methyladenosine (m6A) modification in OS malignancies. Here, we aimed to decipher the pathological significance of RBM15-mediated m6A modification of lncRNA THAP9-AS1 in OS progression.

METHODS

The expression levels of THAP9-AS1 and RBM15 in OS tissues and cell lines was determined by qRT-PCR. Based on the abnormal regulation of THAP9-AS1 and RBM15, the CCK8, colony-formation, and transwell invasion assays were used to evaluate the viability, clone formation capacity, and invasive ability of OS cells. A mouse model of tumor transplantation was utilized to ascertain the role of THAP9-AS1 silencing in vivo. The relationship between THAP9-AS1 and RBM15 was determined by RIP and MeRIP assays.

RESULTS

THAP9-AS1 and RBM15 were significantly elevated in OS. Silencing of THAP9-AS1 or RBM15 decreased the proliferative and invasive ability of OS cells in vitro, and inhibition of THAP9-AS1 delayed the tumorous growth in vivo. Interestingly, THAP9-AS1 binds to RBM15, and was stimulated by RBM15 to promote m6A level and translation. Furthermore, THAP9-AS1 upregulation promoted OS cell invasion and survival, and this promotion of OS cell malignancy was abrogated by RBM15 silencing.

CONCLUSION

THAP9-AS1 serves as a tumor promoter by accelerating the malignant progression of OS by undergoing m6A modification, which is mediated by RBM15. This suggests that RBM15-m6A-THAP9-AS1 may be a potential target for OS treatment.

PRMT5 Inhibition Enhances Therapeutic Efficacy of Cisplatin via Mediating miR-29b-3p-Mcl-1 Expression in Lung Adenocarcinoma

Cisplatin is one of the front-line therapeutic agents used to treat cancers, while drug resistance is a great obstacle to anti-tumor efficiency. Protein arginine methyltransferase 5 (PRMT5) has been identified as a promoter of tumorigenesis, motility, and invasion. Inhibiting PRMT5 reduced hypoxia-induced carboplatin resistance in lung adenocarcinoma (LUAD). However, the specific relationship between PRMT5 and cisplatin (CDDP) warrants further investigation. Our research revealed that PRMT5 inhibitor C9 enhanced CDDP chemosensitivity by suppressing proliferation and promoting apoptosis in LUAD cells. Through examining pro-apoptotic proteins regulated by PRMT5, we identified that Mcl-1 played a significant role in PRMT5-mediated CDDP chemosensitivity. Furthermore, PRMT5 regulated Mcl-1 expression through mediating miR-29b-3p. In vivo, our research presented that C9 increased CDDP chemosensitivity in LUAD xenografts. All in all, our data raised an interesting possibility that epigenetic reprogramming was associated with chemosensitivity. PRMT5 inhibitor C9 improved CDDP effectiveness in LUAD cells by inhibiting Mcl-1 expression via miR-29b-3p, thereby modulating cellular proliferation and apoptosis.

RNA damage and its implications in genome stability

Endogenous and environmental stressors can damage DNA and RNA to compromise genome and transcriptome stability and integrity in cells, leading to genetic instability and diseases. Recent studies have demonstrated that RNA damage can also modulate genome stability via RNA-templated DNA synthesis, suggesting that it is essential to maintain RNA integrity for the sustainment of genome stability. However, little is known about RNA damage and repair and their roles in modulating genome stability. Current efforts have mainly focused on revealing RNA surveillance pathways that detect and degrade damaged RNA, while the critical role of RNA repair is often overlooked. Due to their abundance and susceptibility to nucleobase damaging agents, it is essential for cells to evolve robust RNA repair mechanisms that can remove RNA damage, maintaining RNA integrity during gene transcription. This is supported by the discovery of the alkylated RNA nucleobase repair enzyme human AlkB homolog 3 that can directly remove the methyl group on damaged RNA nucleobases, predominantly in the nucleus of human cells, thereby restoring the integrity of the damaged RNA nucleobases. This is further supported by the fact that several DNA repair enzymes can also process RNA damage. In this review, we discuss RNA damage and its effects on cellular function, DNA repair, genome instability, and potential RNA damage repair mechanisms. Our review underscores the necessity for future research on RNA damage and repair and their essential roles in modulating genome stability.

Research progress on N6-Methyladenosine modification in angiogenesis, vasculogenic mimicry, and therapeutic implications in breast cancer

N6-methyladenosine (m6A) modification is the most common epitranscriptomic modification in eukaryotic RNA and has garnered extensive attention in the context of breast cancer research. The m6A modification significantly impacts tumorigenesis and tumor progression by regulating RNA stability, splicing, translation, and degradation. In this review we summarize recent advances in understanding the roles of m6A modification in the mechanisms underlying angiogenesis and vasculogenic mimicry in breast cancer. We review how m6A modification and associated transcripts influence relevant factors by affecting key factors and signaling pathways, highlighting the interactions among m6A "writers," "erasers," and "readers," and their overall impact on tumor angiogenesis and vasculogenic mimicry, as well as potential new therapeutic targets.

An effective cell-penetrating peptide-based loading method to extracellular vesicles and enhancement in cellular delivery of drugs

Extracellular vesicles (EVs) have been demonstrated to own the advantages in evading phagocytosis, crossing biological barriers, and possessing excellent biocompatibility and intrinsic stability. Based on these characteristics, EVs have been used as effective therapeutic carriers for drug delivery, but the low drug loading capacity greatly limits further applications. Herein, we developed a drug loading method based on cell-penetrating peptide (CPP) to enhance the encapsulation of therapeutic reagents in EVs, and EVs-based drug delivery system achieved higher killing efficacy to tumor cells. Urinary EVs and chemotherapy reagent doxorubicin (DOX) were used as model. It is easy to conjugate CPP with DOX (CPP-DOX) through the linker N-succinimidyl 3-maleimidopropionate (SMP). CPP-DOX was incubated with EVs under a mild condition, promoting the encapsulation of DOX into EV cavities. CPP-DOX-EVs showed strong anticancer ability since EVs delivery facilitated the uptake by cancer cells. EVs loading of CPP-DOX exhibited higher drug loading efficiency at 37.18%, presenting about 2.5 times increase in efficiency over EVs loading of DOX through passive incubation. Easy operation and controllable condition further reinforce the advantages compared with other loading methods. CPP-based drug loading method provides an effective strategy for EVs-based drug delivery system.

Exploring the methyl-verse: Dynamic interplay of epigenome and m6A epitranscriptome

The orchestration of dynamic epigenetic and epitranscriptomic modifications is pivotal for the fine-tuning of gene expression. However, these modifications are traditionally examined independently. Recent compelling studies have disclosed an interesting communication and interplay between m6A RNA methylation (m6A epitranscriptome) and epigenetic modifications, enabling the formation of feedback circuits and cooperative networks. Intriguingly, the interaction between m6A and DNA methylation machinery, coupled with the crosstalk between m6A RNA and histone modifications shape the transcriptional profile and translational efficiency. Moreover, m6A modifications interact also with non-coding RNAs, modulating their stability, abundance, and regulatory functions. In the light of these findings, m6A imprinting acts as a versatile checkpoint, linking epigenetic and epitranscriptomic layers toward a multilayer and time-dependent control of gene expression and cellular homeostasis. The scope of the present review is to decipher the m6A-coordinated circuits with DNA imprinting, chromatin architecture, and non-coding RNAs networks in normal physiology and carcinogenesis. Ultimately, we summarize the development of innovative CRISPR-dCas engineering platforms fused with m6A catalytic components (m6A writers or erasers) to achieve transcript-specific editing of m6A epitranscriptomes that can create new insights in modern RNA therapeutics.

N6-methyladenosine (m6A) RNA methylation of LncRNA LINC01214 accelerates the progression of non-small cell lung cancer (NSCLC) by targeting miR-195-5p/ROCK1 axis

Long non-coding RNA LINC01214 is reported to be up-regulated in non-small cell lung cancer (NSCLC), however, its function in NSCLC has not been elucidated yet. In our study, we verified that LINC01214 was aberrantly higher in the tumor tissues and cell lines than that in the normal controls, and was relevant to the severity and prognosis of NSCLC through using real-time quantitative PCR. Then, 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide assay and flow cytometry illustrated that knocking down LINC01214 restrained cell proliferation and promoted apoptosis in A549 and H1299 cells. Additionally, western blot results confirmed that LINC01214 silence reduced the protein expression of CDK2, CDK6, CyclinD1 and Bcl2, but increased the protein expression of Bax and Caspase-3. Of note, compared to normal cells, NSCLC cells had higher enrichment level of N6-methyladenosine (m6A) modification of LINC01214, while reducing m6A modification of LINC01214 weakened the stability of LINC01214 and diminished its level in A549 and H1299 through down-regulating methyltransferase METTL3 or overexpressing demethylase ALKBH5. Subsequently, molecular experiments proved that LINC01214 acted as a sponge for miR-195-5p to elevate ROCK1 expression in NSCLC. Furthermore, data from functional recovery experiments showed that elevating miR-195-5p also exerted tumor-suppressive effects in NSCLC; meanwhile, the effects were reversed by overexpressing ROCK1 or inhibiting miR-195-5p. In short, m6A modification-mediated up-regulation of LINC01214 advances cell proliferation and tumorigenesis to promote NSCLC progression through inhibiting miR-195-5p to up-regulate ROCK1.

Genetically engineered CD276-anchoring biomimetic nanovesicles target senescent escaped tumor cells to overcome chemoresistant and immunosuppressive breast cancer

Chemotherapy-induced cellular senescence leads to an increased proportion of cancer stem cells (CSCs) in breast cancer (BC), contributing to recurrence and metastasis, while effective means to clear them are currently lacking. Herein, we aim to develop new approaches for selectively killing senescent-escape CSCs. High CD276 (95.60%) expression in multidrug-resistant BC cells, facilitates immune evasion by low-immunogenic senescent escape CSCs. CALD1, upregulated in ADR-resistant BC, promoting senescent-escape of CSCs with an anti-apoptosis state and upregulating CD276, PD-L1 to promote chemoresistance and immune escape. We have developed a controlled-released thermosensitive hydrogel containing pH- responsive anti-CD276 scFV engineered biomimetic nanovesicles to overcome BC in primary, recurrent, metastatic and abscopal humanized mice models. Nanovesicles coated anti-CD276 scFV selectively fuses with cell membrane of senescent-escape CSCs, then sequentially delivers siCALD1 and ADR due to pH-responsive MnP shell. siCALD1 together with ADR effectively induce apoptosis of CSCs, decrease expression of CD276 and PD-L1, and upregulate MHC I combined with Mn2+ to overcome chemoresistance and promote CD8+T cells infiltration. This combined therapeutic approach reveals insights into immune surveillance evasion by senescent-escape CSCs, offering a promising strategy to immunotherapy effectiveness in cancer therapy.

lncRNA POU6F2-AS1 Regulated by KIAA1429 Contributes to Colorectal Cancer Progression in an m6A Modification Manner

Long non-coding RNAs (lncRNAs) are participated in tumourigenesis, including colorectal cancer (CRC). However, the effects and mechanisms of lncRNA POU6F2-AS1 in CRC have not been investigated. KIAA1429 act as a member of N6-methyladenosine (m6A) modification, has been knew as an oncogenic factor in various cancer containing CRC. We focus to investigate the regulation effect of lncRNA POU6F2-AS1, and the mechanism among lncRNA POU6F2-AS1 and KIAA1429 in CRC. The lncRNA POU6F2-AS1 and KIAA1429 levels in CRC tissue samples as well as cells were clarified by qRT-PCR, and their relationship was predicted by bioinformatics, MeRIP and Pearson analysis. Cell survival, migration and invasion were analyzed via EdU, wound healing and Transwell assays after lncRNA POU6F2-AS1 was down-regulated and KIAA1429 was up-regulated. LncRNA POU6F2-AS1 and KIAA1429 were enriched in CRC tissue samples. LncRNA POU6F2-AS1 silencing suppressed CRC cell survival, migration, and invasion, and KIAA1429 overexpression facilitated CRC cell malignancy. KIAA1429 promoted lncRNA POU6F2-AS1 expression via m6A modification. Furthermore, KIAA1429 upregulation reversed the inhibitory effect of lncRNA POU6F2-AS1 interference on the malignant behavior of CRC cells. lncRNA POU6F2-AS1 was modulated by KIAA1429 in the form of m6A modification to regulate the malignant phenotype of CRC, which may provide new insights into the potential application of KIAA1429-m6A-lncRNA POU6F2-AS1-based CRC therapy.

Regulation of hsa_circ_0112136 by m6A demethylase FTO can enhance the malignancy of gastric cancer via the regulation of the PI3K/AKT/mTOR pathway

A growing body of research highlights the role that N6-methyladenosine (m6A) modification and circular RNAs (circRNAs) play in gastric cancer (GC) cases. However, studies elucidating the function and mechanism of the recently discovered circRNA hsa_circ_0112136 in GC are limited. This study aimed to examine the pathophysiology of GC progression due to fat mass and obesity-associated protein (FTO)-mediated N6-methyladenosine (m6A) modification of hsa_circ_0112136. The hsa_circ_0112136 and FTO levels in the GC samples were analyzed using qRT-PCR. The Transwell invasion assay, wound healing assay, and CCK8 assays were employed to assess alterations in GC cell invasiveness, migration, and viability due to the aberrant regulation of hsa_circ_0112136 and FTO. Phosphorylated PI3K, AKT, and mTOR (the key proteins of the PI3K/AKT/mTOR pathway) were detected via western blotting after hsa_circ_0112136 suppression. A tumor transplantation mouse model was constructed to evaluate the suppression of hsa_circ_0112136's function in vivo. The correlation among hsa_circ_0112136 and FTO was identified using the MeRIP assay. Levels of hsa_circ_0112136 and FTO were evidently elevated in GC samples. Suppression of has_circ_0112136 reduced the viability, migration, and invasive ability of GC cells in vitro, as well as delayed tumor growth in vivo via suppression of the activation of the PI3K/AKT/mTOR pathway. FTO decreased hsa_circ_0112136 m6A levels and enhanced hsa_circ_0112136 expression. Furthermore, FTO upregulation enhanced GC cell invasion, migration, and survival, which was reversed by hsa_circ_0112136 suppression. Our study proposes that hsa_circ_0112136 functions as a tumor promoter, facilitating the malignant progression of GC through m6A modification (suppressed by FTO) and activating the PI3K/AKT/mTOR pathway. This suggests that targeting FTO-m6A-hsa_circ_0112136-PI3K/AKT/mTOR may be a novel approach for GC intervention.

RNA methylation and breast cancer: insights into m6A, m7G and m5C

Breast cancer remains the most commonly diagnosed cancer in female worldwide, marked by its molecular diversity and complex subtypes. Despite progress in targeted therapies, tumor heterogeneity and treatment resistance continue to present major challenges. Recent studies emphasize the crucial role of RNA modifications in cancer biology, with nearly 200 distinct modifications identified. Among these, methylation is particularly significant, with methylation-related factors emerging as key regulators of RNA metabolism, influencing cancer progression, metastasis, and treatment resistance. This review focuses on the roles of key RNA methylation in breast cancer, particularly N6-methyladenosine (m6A), N7-methylguanosine (m7G), 5-methylcytosine (m5C), N1-methyladenosine (m1A), and N3-methylcytidine (m3C). We examine the functions of m6A "writers" like METTL3 and METTL14, and "readers" such as the YTH domain family in modulating tumor behavior. Dysregulation of m6A "erasers" like FTO and ALKBH5 are noticed too, highlighting their impact on cancer stem cell phenotypes, chemoresistance, and immune evasion. Additionally, the role of m7G modifications in mRNA stability and translation, facilitated by METTL1/WDR4 and RNMT, is discussed as a potential therapeutic target. The involvement of m5C, m1A, and m3C modifications, particularly those mediated by NSUN2 and NSUN6, in breast cancer tumorigenesis and prognosis is also reviewed. Despite coding RNAs, the interplay between these RNA methylations and non-coding RNAs, such as lncRNAs and miRNAs, is explored, shedding light on their roles in cancer cell proliferation, invasion, and immune response modulation. This review highlights the potential of RNA methylations as novel therapeutic targets in breast cancer, offering insights for precision medicine and improved patient outcomes.

Improved Therapeutic Efficacy of Doxorubicin Chemotherapy With Cannabidiol in 4T1 Mice Breast Cancer Model

BACKGROUND

High dose chemotherapy is one of the therapeutic strategies for breast cancer and doxorubicin (DOX) as a chemotherapy agent is widely used. DOX indication is limited due to its dose-depended cardiotoxicity. Recently, cannabidiol (CBD) shows antitumoral and cardioprotective effects, so we hypothesized that CBD administration with high-dose DOX chemotherapy can improve anticancer activity and reduce cardiotoxic side effects.

METHOD

Mice breast cancer model established by injecting 4T1 cell lines. One group was not injected by 4T1 cells as a not cancerous group and received normal saline (NS, 0.1 mL). In cancerous groups, first group was considered as cancerous control and received NS (0.1 mL); the second group received CBD (5 mg/kg, IP) on Days 1,7, and 14; in the third group DOX (5 mg/kg, IV) as CBD schedule was administrated; the fourth group treated with CBD 1 day before DOX injection as pretreatment, and the last group was treated with CBD and DOX at same time with previous doses and schedules. On Day 21, all mice were sacrificed, heart and lungs tissues were obtained and histological sections were isolated. SOD2, iNOS, MMP2, MMP9 were evaluated through western blot and TUNEL test preformed for breast tumor.

RESULTS

Tumor size and weight significantly decreased in DOX, pretreatment CBD + DOX and CBD + DOX groups. Administration of CBD with DOX could not prevent weight loss. TUNEL test demonstrated the highest tumor cell apoptosis in pretreatment CBD + DOX and CBD + DOX. In lungs belonged to CBD + DOX, there was not any sign of metastasis. Cardiac histopathological examination of pretreatment CBD + DOX and CBD + DOX did not show any sign of congestion or inflammation. In CBD + DOX SOD2 increased, also iNOS, MMP2, and MMP9 decreased compared to DOX.

CONCLUSIONS

This study demonstrated that simultaneous administration of CBD and DOX can increase antitumoral effect and reduce DOX cardiotoxicity. Nevertheless, CBD can induce cardiotoxicity as administrated alone.

METTL3-mediated m6A modification promotes chemoresistance of intrahepatic cholangiocarcinoma by up-regulating NRF2 to inhibit ferroptosis in cisplatin-resistant cells

This study explores the relationship between m6A modification and ferroptosis in intrahepatic cholangiocarcinoma (ICC) and its impact on cisplatin resistance. We established cisplatin-resistant cells. CCK-8 and Transwell assays were conducted to evaluate the effects of METTL3 on drug resistance, migration, and invasion. RT-qPCR and Western blotting were used to measure target gene expression and the effects of overexpression and suppression. RIP, luciferase reporter assay, and other experiments were utilized to investigate the interaction between METTL3 and NRF2. Additionally, rescue experiments were performed to confirm the role of the METTL3/NRF2 axis in tumor drug resistance. METTL3 was found to be highly expressed in cisplatin-resistant cells, enhancing m6A modification levels, stabilizing NRF2 mRNA, and increasing NRF2 protein expression to inhibit ferroptosis. These findings indicate that the METTL3/NRF2 axis inhibits ferroptosis in cisplatin-resistant cells, thereby promoting chemotherapy resistance in ICC. This provides a potential direction for future research and treatment of ICC.

Unraveling the landscape of m6A RNA methylation in wound healing and scars

Wound healing is a complex process involving sequential stages of hemostasis, inflammation, proliferation, and remodeling. Multiple cell types and factors, including underlying conditions like diabetes and bacterial colonization, can influence healing outcomes and scar formation. N6-methyladenosine (m6A), a predominant RNA modification, plays crucial roles in gene expression regulation, impacting various biological processes and diseases. m6A regulates embryonic skin morphogenesis, wound repair, and pathophysiological processes like inflammation and angiogenesis. Recent studies have highlighted the role of m6A in wound healing, scar formation, and tissue remodeling. Additionally, m6A presents a unique expression pattern in pathological wounds and scars, potentially influencing wound healing and scar formation through modulating gene expression and cellular signaling, thereby serving as potential biomarkers or therapeutic targets. Targeting m6A modifications are potential strategies to enhance wound healing and reduce scar formation. This review aims to explore the roles and mechanisms of m6A RNA methylation in wound healing and scars, and discuss current challenges and perspectives. Continued research in this field will provide significant value for optimal wound repair and scar treatment.

Arginine methylation and respiratory disease

Arginine methylation, a vital post-translational modification, plays a pivotal role in numerous cellular functions such as signal transduction, DNA damage response and repair, regulation of gene transcription, mRNA splicing, and protein interactions. Central to this modification is the role of protein arginine methyltransferases (PRMTs), which have been increasingly recognized for their involvement in the pathogenesis of various respiratory diseases. This review begins with an exploration of the biochemical underpinnings of arginine methylation, shedding light on the intricate molecular regulatory mechanisms governed by PRMTs. It then delves into the impact of arginine methylation and the dysregulation of arginine methyltransferases in diverse pulmonary disorders. Concluding with a focus on the therapeutic potential and recent advancements in PRMT inhibitors, this article aims to offer novel perspectives and therapeutic avenues for the management and treatment of respiratory diseases.

N6-methyladenosine modification of linc-OIP5 confers paclitaxel resistance in breast cancer through a DDX5-dependent mechanism

Chemoresistance is a significant obstacle in the treatment of breast cancer (BC). Due to its diverse composition, the causes of chemoresistance in BC are complex and have not been completely understood. In this article, we explored the mechanism of N6-methyladenosine (m6A)-modified long intervening noncoding RNA (linc)-OIP5 in BC chemoresistance. We successfully constructed drug-resistant cell lines MCF-7/P and MDA-MB-231/P by exposing parental MDA-MB-231 and MCF-7 cells to escalating doses of paclitaxel (PTX) and revealed multiple m6A methylation modification sites on linc-OIP5 according to the predictive analysis of the SRAMP database. Linc-OIP5 expression and m6A modification were up-regulated in PTX-resistant BC cells. Inhibition of m6A modification or linc-OIP5 knockdown facilitated PTX-resistant and parental BC cell apoptosis and repressed proliferation and migration. Mechanistically, linc-OIP5 bound to TRIM5 and reduced the ubiquitination of DDX5, thus stabilizing the DDX5 protein. Additionally, DDX5 overexpression partly abrogated the suppressing effects of inhibited m6A modification or si-linc-OIP5 on cell proliferation, migration and PTX resistance. These findings indicate that m6A-modified linc-OIP5 reduced DDX5 ubiquitination and enhanced DDX5 stability by binding to TRIM5, thereby promoting BC cell proliferation, migration and PTX resistance, and inhibiting apoptosis.

KIAA1429 promotes the malignancy of oral squamous cell carcinoma by regulating CA9 m6A methylation

KIAA1429 has been reported as a cancer regulator, but its role and mechanism in the progression of oral squamous cell carcinoma (OSCC) remain elusive. The objective of the present research was to figure out the effect of KIAA1429 regulated CA9 on the progression of OSCC. Using qRT-PCR and bioinformatics analysis, we studied the expression levels of KIAA1429 and CA9 in OSCC tissue samples. The functional roles of KIAA1429 and CA9 were assessed using transwell and CCK-8 assays. The regulation among KIAA1429 and CA9 was investigated using MeRIP and western blotting assays. In addition, the m6A level in OSCC was measured utilizing RNA m6A quantification. In OSCC, KIAA1429 and m6A levels were upregulated. We observed that KIAA1429 inhibition declined proliferation, migration, and invasion of OSCC cells and decreased cell growth in vivo. Furthermore, KIAA1429 serves as a crucial upstream regulator of CA9 in OSCC and upregulates CA9 expression through an m6A-dependent mechanism. We observed that CA9 was upregulated in OSCC samples and that low expression of KIAA1429 partially restored the enhanced malignant phenotype caused by CA9 overexpression. Overall, our findings suggest that KIAA1429 and CA9 act as pro-oncogenic factors in OSCC, with KIAA1429 promoting OSCC malignancy through m6A modification-dependent stabilization of CA9 transcripts, which represents a novel regulatory mechanism in OSCC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00640-3.

YTHDF2 in peritumoral hepatocytes mediates chemotherapy-induced antitumor immune responses through CX3CL1-mediated CD8+ T cell recruitment

Peritumoral hepatocytes are critical components of the liver cancer microenvironment, However, the role of peritumoral hepatocytes in the local tumor immune interface and the underlying molecular mechanisms have not been elucidated. YTHDF2, an RNA N6-methyladenosine (m6A) reader, is critical for liver tumor progression. The function and regulatory roles of YTHDF2 in peritumoral hepatocytes are unknown. This study demonstrated that oxaliplatin (OXA) upregulated m6A modification and YTHDF2 expression in hepatocytes. Studies using tumor-bearing liver-specific Ythdf2 knockout mice revealed that hepatocyte YTHDF2 suppresses liver tumor growth through CD8+ T cell recruitment and activation. Additionally, YTHDF2 mediated the response to immunotherapy. Mechanistically, OXA upregulated YTHDF2 expression by activating the cGAS-STING signaling pathway and consequently enhanced the therapeutic outcomes of immunotherapeutic interventions. Ythdf2 stabilized Cx3cl1 transcripts in an m6A-dependent manner, regulating the interplay between CD8+ T cells and the progression of liver malignancies. Thus, this study elucidated the novel role of hepatocyte YTHDF2, which promotes therapy-induced antitumor immune responses in the liver. The findings of this study provide valuable insights into the mechanism underlying the therapeutic benefits of targeting YTHDF2.

Role of N6-methyladenosine RNA modification in cancer

N6-methyladenosine (m6A) is the most abundant modification of RNA in eukaryotic cells. Previous studies have shown that m6A is pivotal in diverse diseases especially cancer. m6A corelates with the initiation, progression, resistance, invasion, and metastasis of cancer. However, despite these insights, a comprehensive understanding of its specific roles and mechanisms within the complex landscape of cancer is still elusive. This review begins by outlining the key regulatory proteins of m6A modification and their posttranslational modifications (PTMs), as well as the role in chromatin accessibility and transcriptional activity within cancer cells. Additionally, it highlights that m6A modifications impact cancer progression by modulating programmed cell death mechanisms and affecting the tumor microenvironment through various cancer-associated immune cells. Furthermore, the review discusses how microorganisms can induce enduring epigenetic changes and oncogenic effect in microorganism-associated cancers by altering m6A modifications. Last, it delves into the role of m6A modification in cancer immunotherapy, encompassing RNA therapy, immune checkpoint blockade, cytokine therapy, adoptive cell transfer therapy, and direct targeting of m6A regulators. Overall, this review clarifies the multifaceted role of m6A modification in cancer and explores targeted therapies aimed at manipulating m6A modification, aiming to advance cancer research and improve patient outcomes.

Functions and mechanisms of RNA m6A regulators in breast cancer (Review)

Breast cancer (BC) is a major malignant tumor in females and the incidence rate of BC has increased worldwide in recent years. N6‑methyladenosine (m6A) is a methylation modification that occurs extensively in eukaryotic RNA. The abnormal expression of m6A and related regulatory proteins can activate or inhibit certain signal pathways or oncogenes, thus affecting the proliferation, metastasis and prognosis of BC. Numerous studies have shown that m6A regulator disorder exists in BC, and this disorder can be reversed. Therefore, m6A is predicted as a potential therapeutic target for BC. However, the molecular mechanism of m6A RNA methylation regulating the occurrence and development of BC has not been comprehensively elucidated. In this review article, the functions of various m6A regulators and the specific mechanisms of certain regulators of the progress of BC were summarized. Furthermore, the dual role of RNA methylation in tumor progression was discussed, concluding that RNA methylation can not only lead to tumorigenesis but at times give rise to inhibition of tumor formation. In addition, further comprehensive analysis on mechanisms of m6A regulators in BC is conducive to screening effective potential targets and formulating targeted treatment strategies, which will provide new methods for the prevention and treatment of BC.

Role of PRMT1 and PRMT5 in Breast Cancer

Breast cancer is the most common cancer diagnosed in women worldwide. Early-stage breast cancer is curable in ~70-80% of patients, while advanced metastatic breast cancer is considered incurable with current therapies. Breast cancer is a highly heterogeneous disease categorized into three main subtypes based on key markers orientating specific treatment strategies for each subtype. The complexity of breast carcinogenesis is often associated with epigenetic modification regulating different signaling pathways, involved in breast tumor initiation and progression, particularly by the methylation of arginine residues. Protein arginine methyltransferases (PRMT1-9) have emerged, through their ability to methylate histones and non-histone substrates, as essential regulators of cancers. Here, we present an updated overview of the mechanisms by which PRMT1 and PRMT5, two major members of the PRMT family, control important signaling pathways impacting breast tumorigenesis, highlighting them as putative therapeutic targets.

N6-methyladenosine modification of LATS2 promotes hepatoblastoma progression by inhibiting ferroptosis through the YAP1/ATF4/PSAT1 axis

Ferroptosis has attracted extensive interest from cancer researchers due to its substantial potential as a therapeutic target. The role of LATS2, a core component of the Hippo pathway cascade, in ferroptosis initiation in hepatoblastoma (HB) has not yet been investigated. Furthermore, the underlying mechanism of decreased LATS2 expression remains largely unknown. In the present study, we demonstrated decreased LATS2 expression in HB and that LATS2 overexpression inhibits HB cell proliferation by inducing ferroptosis. Increased LATS2 expression reduced glycine and cysteine concentrations via the ATF4/PSAT1 axis. Physical binding between YAP1/ATF4 and the PSAT1 promoter was confirmed through ChIP‒qPCR. Moreover, METTL3 was identified as the writer of the LATS2 mRNA m6A modification at a specific site in the 5' UTR. Subsequently, YTHDF2 recognizes the m6A modification site and recruits the CCR4-NOT complex, leading to its degradation by mRNA deadenylation. In summary, N6-methyladenosine modification of LATS2 facilitates its degradation. Reduced LATS2 expression promotes hepatoblastoma progression by inhibiting ferroptosis through the YAP1/ATF4/PSAT1 axis. Targeting LATS2 is a potential strategy for HB therapy.

Knockdown of NUF2-derived exosomes can inhibit the migration and autophagy of BC cells and improve resistance to doxorubicin

Breast cancer (BC) is the most common type of fatal cancer in women. New therapeutic strategies need to be explored to enhance the efficacy of doxorubicin by overcoming the resistance of BC cells. NUF2 is a component of the Ndc80 centromere complex and is a key substance in mediating mitosis and affects the progression of multiple tumors. However, the role as well as mechanisms of NUF2 resistance in BC remain unclear. This study aims to reveal the role of NUF2 in drug resistance in BC. We here revealed that NUF2 was highly expressed in human BC. NUF2 depletion-derived exosomes blocked the growth of BC cells. Further, NUF2 ablation-derived exosomes inhibited autophagy in BC cells. Also, NUF2 ablation-derived exosomes improved doxorubicin resistance in BC cells. Mechanically, NUF2 ablation-derived exosomes blocked PI3K/AKT/mTOR axis in BC cells. In summary, NUF2 ablation-derived exosomes blocked the autophagy of BC cells and improved doxorubicin resistance via mediating PI3K/AKT/mTOR axis.

Relationship between arginine methylation and vascular calcification

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-‑phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

Synergistic anticancer effects of SMYD2 inhibitor BAY-598 and doxorubicin in non-small cell lung cancer

Background

Non-small cell lung Cancer (NSCLC) persists as a lethal neoplastic manifestation, exhibiting a diminished 5-year survival rate, partially attributable to chemotherapeutic resistance. This investigative endeavor aimed to elucidate the synergistic antineoplastic effects and underlying mechanisms of the SMYD2 inhibitor BAY-598 and the chemotherapeutic agent doxorubicin (DOX) in NSCLC.

Methods

The human non-small cell lung cancer cell lines A549 and H460 were subjected to treatment regimens involving BAY-598 and/or DOX. Cellular viability, apoptotic events, invasive capacity, and migratory potential were evaluated through the implementation of CCK-8 assays, flow cytometric analyses, and Transwell assays, respectively. Protein expression levels were quantified via Western blot analyses. An in vivo xenograft murine model was established to assess therapeutic efficacy.

Results

BAY-598 and DOX synergistically suppressed the viability, invasiveness, and migratory capabilities of NSCLC cells. Co-treatment Promoting cell apoptosis and cell cycle arrest. Additionally, Furthermore, co-administration significantly inhibited cell migration and invasion. Mechanistic studies revealed coordinately inhibited JAK-STAT signaling upon combination treatment. In vivo study further validated the synergistic antitumor efficacy of BAY-598 and DOX against NSCLC xenografts.

Conclusions

Our findings demonstrate that BAY-598 potentiates the anti-cancer effects of DOX in non-small cell lung cancer cells by modulating the JAK/STAT signaling pathway as a synergistic strategy. The combination holds promise as an emerging therapeutic strategy for NSCLC. Further optimization and validation are warranted to promote its translational potential.

Nanoplatform based on carbon nanoparticles loaded with doxorubicin enhances apoptosis by generating reactive oxygen species for effective cancer therapy

At present, due to its wide application and relatively low cost, chemotherapy remains a clinically important cancer treatment option; however, a number of chemotherapeutic drugs have important limitations, such as lack of specificity, high toxicity and side effects, and multi-drug resistance. The emergence of nanocarriers has removed numerous clinical application limitations of certain antitumor chemotherapy drugs and has been widely used in the treatment of tumors with nanodrugs. The present study used carbon nanoparticles (CNPs) as a nanocarrier for doxorubicin (DOX) to form the novel nanomedicine delivery system (CNPs@DOX)was demonstrated by UV-vis and fluorescence spectrophotometry, ζ potential and TEM characterization experiments. The results confirmed the successful preparation of CNPs@DOX nanoparticles with a particle size of 96±17 nm, a wide range of absorption and a negatively charged surface. Furthermore, CNPs@DOX produced more reactive oxygen species and induced apoptosis, and thus exhibited higher cytotoxicity than DOX, which is a small molecule anticancer drug without a nanocarrier delivery system.. The present study provides a strategy for the treatment of tumors with nanomedicine.

Small molecule inhibitors targeting m6A regulators

As the most common form of epigenetic regulation by RNA, N6 methyladenosine (m6A) modification is closely involved in physiological processes, such as growth and development, stem cell renewal and differentiation, and DNA damage response. Meanwhile, its aberrant expression in cancer tissues promotes the development of malignant tumors, as well as plays important roles in proliferation, metastasis, drug resistance, immunity and prognosis. This close association between m6A and cancers has garnered substantial attention in recent years. An increasing number of small molecules have emerged as potential agents to target m6A regulators for cancer treatment. These molecules target the epigenetic level, enabling precise intervention in RNA modifications and efficiently disrupting the survival mechanisms of tumor cells, thus paving the way for novel approaches in cancer treatment. However, there is currently a lack of a comprehensive review on small molecules targeting m6A regulators for anti-tumor. Here, we have comprehensively summarized the classification and functions of m6A regulators, elucidating their interactions with the proliferation, metastasis, drug resistance, and immune responses in common cancers. Furthermore, we have provided a comprehensive overview on the development, mode of action, pharmacology and structure-activity relationships of small molecules targeting m6A regulators. Our aim is to offer insights for subsequent drug design and optimization, while also providing an outlook on future prospects for small molecule development targeting m6A.

METTL3-deficiency m6A-dependently degrades MALAT1 to suppress NLRP3-mediated pyroptotic cell death and inflammation in Mycobacterium tuberculosis (H37Ra strain)-infected mouse macrophages

Mycobacterium tuberculosis (Mtb)-infected macrophages aggravated the development of pulmonary tuberculosis, but its detailed molecular mechanisms are still largely unknown. Here, the mouse primary peritoneal macrophages were infected with the attenuated strain of Mtb H37Ra, and we firstly verified that targeting a novel METTL3/N6-Methyladenosine (m6A)/LncRNA MALAT1/miR-125b/TLR4 axis was effective to suppress pyroptotic cell death in the Mtb-infected macrophages. Specifically, through performing Real-Time qPCR and Western Blot analysis, we validated that METTL3, LncRNA MALAT1 and TLR4 were elevated, whereas miR-125b and the anti-oxidant agents (Nrf2 and HO-1) were downregulated in Mtb-infected mouse macrophages. In addition, functional experiments confirmed that both ROS scavenger NAC and METTL3-ablation downregulated NLRP3, GSDMD-C, cleaved Caspase-1 and ASC to restrain pyroptotic cell death and decreased the expression levels of IL-1β, IL-18, IL-6 and TNF-α to restrain inflammatory cytokines expression in Mtb-infected macrophages. Next, METTL3-ablation induced m6A-demethylation and instability in LncRNA MALAT1, and low-expressed LncRNA MALAT1 caused TLR4 downregulation through sponging miR-125b, resulting in the inactivation of NLRP3 inflammasome. Finally, silencing of METTL3-induced protective effects in Mtb-infected macrophages were all abrogated by overexpressing LncRNA MALAT1 and downregulating miR-125b. Thus, we concluded that targeting METTL3-mediated m6A modifications suppressed Mtb-induced pyroptotic cell death in mouse macrophages, and the downstream LncRNA MALAT1/miR-125b/TLR4 axis played critical role in this process.

HNRNPC promotes estrogen receptor-positive breast cancer cell cycle by stabilizing WDR77 mRNA in an m6A-dependent manner

Breast cancer has become the most commonly diagnosed cancer. Heterogeneous nuclear ribonucleoprotein C (HNRNPC), a reader of N6-methyladenosine (m6A), has been observed to be upregulated in various types of cancer. Nevertheless, the role of HNRNPC in breast cancer and whether it is regulated by m6A modification deserve further investigation. The expression of HNRNPC in breast cancer was examined by quantitative real-time polymerase chain reaction and western blot analysis. RNA immunoprecipitation was performed to validate the binding relationships between HNRNPC and WD repeat domain 77 (WDR77). The effects of HNRNPC and m6A regulators on WDR77 were investigated by actinomycin D assay. The experiments in vivo were conducted in xenograft models. In this research, we found that HNRNPC was highly expressed in breast cancer, and played a crucial role in cell growth, especially in the luminal subtype. HNRNPC could combine and stabilize WDR77 mRNA. WDR77 successively drove the G1/S phase transition in the cell cycle and promoted cell proliferation. Notably, this regulation axis was closely tied to the m6A modification status of WDR77 mRNA. Overall, a critical regulatory mechanism was identified, as well as promising targets for potential treatment strategies for luminal breast cancer.

Epigenetic deregulation in breast cancer microenvironment: Implications for tumor progression and therapeutic strategies

Breast cancer comprises a substantial proportion of cancer diagnoses in women and is a primary cause of cancer-related mortality. While hormone-responsive cases generally have a favorable prognosis, the aggressive nature of triple-negative breast cancer presents challenges, with intrinsic resistance to established treatments being a persistent issue. The complexity intensifies with the emergence of acquired resistance, further complicating the management of breast cancer. Epigenetic changes, encompassing DNA methylation, histone and RNA modifications, and non-coding RNAs, are acknowledged as crucial contributors to the heterogeneity of breast cancer. The unique epigenetic landscape harbored by each cellular component within the tumor microenvironment (TME) adds great diversity to the intricate regulations which influence therapeutic responses. The TME, a sophisticated ecosystem of cellular and non-cellular elements interacting with tumor cells, establishes an immunosuppressive microenvironment and fuels processes such as tumor growth, angiogenesis, and extracellular matrix remodeling. These factors contribute to challenging conditions in cancer treatment by fostering a hypoxic environment, inducing metabolic stress, and creating physical barriers to drug delivery. This article delves into the complex connections between breast cancer treatment response, underlying epigenetic changes, and vital interactions within the TME. To restore sensitivity to treatment, it emphasizes the need for combination therapies considering epigenetic changes specific to individual members of the TME. Recognizing the pivotal role of epigenetics in drug resistance and comprehending the specificities of breast TME is essential for devising more effective therapeutic strategies. The development of reliable biomarkers for patient stratification will facilitate tailored and precise treatment approaches.

TGF-β2-induced alterations of m6A methylation in hTERT RPE-1 cells

N6-methyladenosine (m6A) is a major type of RNA modification implicated in various pathophysiological processes. Transforming growth factor β2 (TGF-β2) induces epithelial-mesenchymal transition (EMT) in retinal pigmental epithelial (RPE) cells and promotes the progression of proliferative vitreoretinopathy (PVR). However, the role of m6A methylation in the EMT of human telomerase reverse transcriptase (hTERT) retinal pigmental epithelium (RPE)-1 cells has not been clarified. Here, we extracted RNA from RPE cells subjected to 0 or 20 ng/mL TGF-β2 for 72 h and identified differentially methylated genes (DMGs) by m6A-Seq and differentially expressed genes (DEGs) by RNA-Seq. We selected the genes related to EMT by conjoint m6A-Seq/RNA-Seq analysis and verified them by qRT-PCR. We then confirmed the function of m6A methylation in the EMT of RPE cells by knocking down the methyltransferase METTL3 and the m6A reading protein YTHDF1. Sequencing yielded 5814 DMGs and 1607 DEGs. Conjoint analysis selected 467 genes altered at the m6A and RNA levels that are closely associated with the EMT-related TGF-β, AGE-RAGE, PI3K-Akt, P53, and Wnt signaling pathways. We also identified ten core EMT genes ACTG2, BMP6, CDH2, LOXL2, SNAIL1, SPARC, BMP4, EMP3, FOXM1, and MYC. Their RNA levels were evaluated by qRT-PCR and were consistent with the sequencing results. We observed that METTL3 knockdown enhanced RPE cell migration and significantly upregulated the EMT markers N-cadherin (encoded by CDH2), fibronectin (FN), Snail family transcription repressor (SLUG), and vimentin. However, YTHDF1 knockdown had the opposite effects and decreased both cell migration and the N-cadherin, FN, and SLUG expression levels. The present study clarified TGF-β2-induced m6A- and RNA-level differences in RPE cells, indicated that m6A methylation might regulate EMT marker expression, and showed that m6A could regulate TGF-β2-induced EMT.

CircZCCHC2 decreases pirarubicin sensitivity and promotes triple-negative breast cancer development via the miR-1200/TPR axis

Triple-negative breast cancer (TNBC) has attracted attention due to its poor prognosis and limited treatment options. The mechanisms underlying the association between circular RNAs (circRNAs) and the occurrence and development of TNBC remain unclear. CircZCCHC2 is observed to be upregulated in TNBC cells, tissues, and plasma exosomes. Knockdown of circZCCHC2 inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition of TNBC cells in vitro and in vivo. Pirarubicin (THP) treatment downregulated circZCCHC2, and circZCCHC2 affected the sensitivity to THP. CircZCCHC2/miR-1200/translocated promoter region, the nuclear basket protein (TPR) pathway was cascaded and verified. It is demonstrated that circZCCHC2 plays a crucial role in the malignant progression of TNBC via the miR-1200/TPR axis, thereby activating the RAS-RAF-MEK-ERK pathway. The present results indicate that circZCCHC2 has the potential to serve as a novel prognostic biomarker for TNBC.

Exosome-shuttled FTO from BM-MSCs contributes to cancer malignancy and chemoresistance in acute myeloid leukemia by inducing m6A-demethylation: A nano-based investigation

Although bone marrow mesenchymal stem cells (BM-MSCs)-derived exosomes have been reported to be closely associated with acute myeloid leukemia (AML) progression and chemo-resistance, but its detailed functions and molecular mechanisms have not been fully delineated. Besides, serum RNA m6A demethylase fat mass and obesity-associated protein (FTO)-containing exosomes are deemed as important indicators for cancer progression, and this study aimed to investigate the role of BM-MSCs-derived FTO-exosomes in regulating the malignant phenotypes of AML cells. Here, we verified that BM-MSCs-derived exosomes delivered FTO to promote cancer aggressiveness, stem cell properties and Cytosine arabinoside (Ara-C)-chemoresistance in AML cells, and the underlying mechanisms were also uncovered. Our data suggested that BM-MSCs-derived FTO-exo demethylated m6A modifications in the m6A-modified LncRNA GLCC1 to facilitate its combination with the RNA-binding protein Hu antigen R (HuR), which further increased the stability and expression levels of LncRNA GLCC1. In addition, LncRNA GLCC1 was verified as an oncogene to facilitate cell proliferation and enhanced Ara-C-chemoresistance in AML cells. Further experiments confirmed that demethylated LncRNA GLCC1 served as scaffold to facilitate the formation of the IGF2 mRNA binding protein 1 (IGF2BP1)-c-Myc complex, which led to the activation of the downstream tumor-promoting c-Myc-associated signal pathways. Moreover, our rescuing experiments validated that the promoting effects of BM-MSCs-derived FTO-exo on cancer aggressiveness and drug resistance in AML cells were abrogated by silencing LncRNA GLCC1 and c-Myc. Thus, the present firstly investigated the functions and underlying mechanisms by which BM-MSCs-derived FTO-exo enhanced cancer aggressiveness and chemo-resistance in AML by modulating the LncRNA GLCC1-IGF2BP1-c-Myc signal pathway, and our work provided novel biomarkers for the diagnosis, treatment and therapy of AML in clinic.

Knowledge mapping and current trends of m6A methylation in the field of cancer

Background

Cancer is a serious threat to people's lives and health, killing millions of people every year. Here, we performed a bibliometric analysis of tumor N6-methyladenosine methylation data between 2001 and 2022 to understand research trends and potential future directions.

Methods

A total of 890 papers published in the Web of Science core collection database between January 1, 2001 and December 31, 2022 were analyzed. Bibliometric analysis was performed using VOSviewer software to explore citations, co-authorship, co-citations, and co-occurrence.

Results

Although few papers were published before 2018, there was a rapid increase in publications after 2018. The People's Republic of China published 810 papers with 16,957 citations, both ranking first in the word. Sun Yat Sen University had the highest number of citations and published articles (67 published papers and 2702 citations), indicative of its active collaborative research status. Wang Xiao was the most co-cited author with 546 co-citations. Huang Yufei and Meng Jia ranked first with a link strength of 22, making them the most active collaborative authors. Frontiers in Oncology and Nature were the most active and co-cited journals, with 57 papers and 1953 co-citations, respectively. Studies of tumor N6-methyladenosine methylation can be divided into three categories: "tumor metabolism", "tumor bioinformatics and immunity", and "tumor progression".

Conclusions

This study systematically summarized the research on tumor N6-methyladenosine methylation during the past 20 years and suggested potential ways to explore its biomarkers and immunotherapy in the future.

KIT mutations and expression: current knowledge and new insights for overcoming IM resistance in GIST

Gastrointestinal stromal tumor (GIST) is the most common sarcoma located in gastrointestinal tract and derived from the interstitial cell of Cajal (ICC) lineage. Both ICC and GIST cells highly rely on KIT signal pathway. Clinically, about 80-90% of treatment-naive GIST patients harbor primary KIT mutations, and special KIT-targeted TKI, imatinib (IM) showing dramatic efficacy but resistance invariably occur, 90% of them was due to the second resistance mutations emerging within the KIT gene. Although there are multiple variants of KIT mutant which did not show complete uniform biologic characteristics, most of them have high KIT expression level. Notably, the high expression level of KIT gene is not correlated to its gene amplification. Recently, accumulating evidences strongly indicated that the gene coding, epigenetic regulation, and pre- or post- protein translation of KIT mutants in GIST were quite different from that of wild type (WT) KIT. In this review, we elucidate the biologic mechanism of KIT variants and update the underlying mechanism of the expression of KIT gene, which are exclusively regulated in GIST, providing a promising yet evidence-based therapeutic landscape and possible target for the conquer of IM resistance. Video Abstract.

ALKBH5-Mediated RNA m6 A Methylation Regulates the Migration, Invasion, and Proliferation of Rheumatoid Fibroblast-Like Synoviocytes

OBJECTIVE

Fibroblast-like synoviocytes (FLSs) are critical for promoting joint damage in rheumatoid arthritis (RA). N6 -methyladenosine (m6 A) modification plays key roles in various diseases, but its role in the pathogenesis of RA is largely unknown. Here, we investigate increased demethylase ALKBH5 promotion of proliferation, migration, and invasion of RA FLSs via regulating JARID2 expression.

METHODS

ALKBH5 expression in FLSs was evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot. 5-ethynyl-2'-deoxyuridine, scratch wound healing, and transwell assays were implemented to determine the role of ALKBH5 on RA FLS proliferation, mobility, and migration. Then, m6 A sequencing combined with RNA sequencing was performed to identify the potential targets of ALKBH5. RNA immunoprecipitation and RNA pulldown were then used to validate the interaction between the protein and messenger RNA (mRNA). Collagen-induced arthritis (CIA) and delayed-type hypersensitivity arthritis (DTHA) models were further established to assess the therapeutic potency of ALKBH5 in vivo.

RESULTS

We demonstrated that ALKBH5 expression was increased in FLSs and synovium from RA. Functionally, ALKBH5 knockdown inhibited the proliferation, migration, and invasion of RA FLSs, whereas overexpression of ALKBH5 displayed the opposite effect. Mechanistically, ALKBH5 mediated m6 A modification in the JARID2 mRNA and enhanced its mRNA stability in cooperation with IGF2BP3. Intriguingly, the severity of arthritis was attenuated in mice with DTHA and ALKBH5 knockout or rats with CIA and intra-articular injection of ALKBH5 short hairpin RNA.

CONCLUSION

Our findings suggest that ALKBH5-mediated m6 A modification is crucial for synovial hyperplasia and invasion in RA. ALKBH5 might be a potential therapeutic target for RA and even for dysregulated fibroblasts in a wide range of diseases.

Small molecules targeting selected histone methyltransferases (HMTs) for cancer treatment: Current progress and novel strategies

Histone methyltransferases (HMTs) play a critical role in gene post-translational regulation and diverse physiological processes, and are implicated in a plethora of human diseases, especially cancer. Increasing evidences demonstrate that HMTs may serve as a potential therapeutic target for cancer treatment. Thus, the development of HMTs inhibitor have been pursued with steadily increasing interest over the past decade. However, the disadvantages such as insufficient clinical efficacy, moderate selectivity, and propensity for acquired resistance have hindered the development of conventional HMT inhibitors. New technologies and methods are imperative to enhance the anticancer activity of HMT inhibitors. In this review, we first review the structure and biological functions of the several essential HMTs, such as EZH2, G9a, PRMT5, and DOT1L. The internal relationship between these HMTs and cancer is also expounded. Next, we mainly focus on the latest progress in the development of HMT modulators encompassing dual-target inhibitors, targeted protein degraders and covalent inhibitors from perspectives such as rational design, pharmacodynamics, pharmacokinetics, and clinical status. Lastly, we also discuss the challenges and future directions for HMT-based drug discovery for cancer therapy.

Betaine alleviates doxorubicin-induced nephrotoxicity by preventing oxidative insults, inflammation, and fibrosis through the modulation of Nrf2/HO-1/NLRP3 and TGF-β expression

Doxorubicin (Dox) is an anthracycline antibiotic used to treat various cancers and shows severe toxicity in multiple organ systems, including kidneys. Evidence shows that betaine's antioxidant and anti-inflammatory properties could prevent the onset of several disorders. Hence, the present study aims to investigate the therapeutic potential of betaine on Dox-induced nephrotoxicity (DIN). Nephrotoxicity was induced in male Sprague Dawley rats using Dox at a dose of 4 mg/kg (cumulative dose: 20 mg/kg) by the intraperitoneal route and cotreated with betaine through oral gavage (200 and 400 mg/kg) for 28 days. At the end of the experiment, biochemical, oxidative stress parameters, histopathology, and qRT-PCR were performed. DIN was indicated by elevated serum creatinine, urea, and decreased albumin levels representing kidney damage; the histopathological lesions (increased capsular space, renal tubule damage, and fibrosis) in renal tissues supported these biochemical findings. Interestingly, betaine treatment improves these alterations in Dox-treated rats. Further, betaine treatment decreases the lipid peroxidation and nitrite concentration and increases the superoxide dismutases and catalase enzyme concentration in Dox-treated rats. Fascinatingly, at the molecular level, DIN in rats shows upregulation of the Nrf2/HO-1 gene, while betaine treatment attenuated its expression along with the downregulation of inflammatory genes (NLRP3, TLR-4, TNF-α, and IL-6) and fibrosis-related genes (TGF-β and Acta2) expression in Dox-treated rats. These results showed that betaine has reno-protective properties by reducing inflammatory and fibrotic mediators and enhancing antioxidant capacity in the renal tissue of rats treated with Dox. We believe betaine can be exploited as a dietary supplement to attenuate DIN.

The Role of m6A-Mediated DNA Damage Repair in Tumor Development and Chemoradiotherapy Resistance

Among the post-transcriptional modifications, m6A RNA methylation has gained significant research interest due to its critical role in regulating transcriptional expression. This modification affects RNA metabolism in several ways, including processing, nuclear export, translation, and decay, making it one of the most abundant transcriptional modifications and a crucial regulator of gene expression. The dysregulation of m6A RNA methylation-related proteins in many tumors has been shown to lead to the upregulation of oncoprotein expression, tumor initiation, proliferation, cancer cell progression, and metastasis.Although the impact of m6A RNA methylation on cancer cell growth and proliferation has been extensively studied, its role in DNA repair processes, which are crucial to the pathogenesis of various diseases, including cancer, remains unclear. However, recent studies have shown accumulating evidence that m6A RNA methylation significantly affects DNA repair processes and may play a role in cancer drug resistance. Therefore, a comprehensive literature review is necessary to explore the potential biological role of m6A-modified DNA repair processes in human cancer and cancer drug resistance.In conclusion, m6A RNA methylation is a crucial regulator of gene expression and a potential player in cancer development and drug resistance. Its dysregulation in many tumors leads to the upregulation of oncoprotein expression and tumor progression. Furthermore, the impact of m6A RNA methylation on DNA repair processes, although unclear, may play a crucial role in cancer drug resistance. Therefore, further studies are warranted to better understand the potential biological role of m6A-modified DNA repair processes in human cancer and cancer drug resistance.

LAMA3 Promotes Tumorigenesis of Oral Squamous Cell Carcinoma by METTL3-Mediated N6-Methyladenosine Modification

Laminin subunit alpha 3 (LAMA3) is a cancer regulator. However, its effects and regulatory pathways in oral squamous cell carcinoma (OSCC) progression remain unknown. This research aimed to determine the influence of LAMA3 regulation via methyltransferase-like 3 (METTL3) on OSCC progression. Using quantitative real-time polymerase chain reaction and bioinformatics analysis, the expression levels of LAMA3 and METTL3 in OSCC tissues were examined. The functional roles of LAMA3 and METTL3 were analyzed using cell functional experiments. Using methylated RNA immunoprecipitation and mRNA stability assays, LAMA3 and METTL3 regulation was investigated. In OSCC tissues, LAMA3 was upregulated. LAMA3 inhibition hampered OSCC cell proliferation, invasion, and migration while its overexpression facilitated OSCC cell progression. METTL3 serves as a crucial upstream regulator of LAMA3 in OSCC and upregulates LAMA3 expression via an m6A-dependent mechanism. The low METTL3 expression partially restored the enhanced malignant phenotype induced by LAMA3 overexpression. Our findings indicate that METTL3 and LAMA3 act as pro-oncogenic factors in OSCC, with METTL3 promoting OSCC malignancy via m6A modification-dependent stabilization of LAMA3 transcripts, representing a novel regulatory mechanism in OSCC.

Betaine alleviates doxorubicin‐induced nephrotoxicity by preventing oxidative insults, inflammation, and fibrosis through the modulation of Nrf2/HO−1/NLRP3 and TGF‐β expression

Doxorubicin (Dox) is an anthracycline antibiotic used to treat various cancers and shows severe toxicity in multiple organ systems, including kidneys. Evidence shows that betaine's antioxidant and anti‐inflammatory properties could prevent the onset of several disorders. Hence, the present study aims to investigate the therapeutic potential of betaine on Dox‐induced nephrotoxicity (DIN). Nephrotoxicity was induced in male Sprague Dawley rats using Dox at a dose of 4 mg/kg (cumulative dose: 20 mg/kg) by the intraperitoneal route and cotreated with betaine through oral gavage (200 and 400 mg/kg) for 28 days. At the end of the experiment, biochemical, oxidative stress parameters, histopathology, and qRT‐PCR were performed. DIN was indicated by elevated serum creatinine, urea, and decreased albumin levels representing kidney damage; the histopathological lesions (increased capsular space, renal tubule damage, and fibrosis) in renal tissues supported these biochemical findings. Interestingly, betaine treatment improves these alterations in Dox‐treated rats. Further, betaine treatment decreases the lipid peroxidation and nitrite concentration and increases the superoxide dismutases and catalase enzyme concentration in Dox‐treated rats. Fascinatingly, at the molecular level, DIN in rats shows upregulation of the Nrf2/HO‐1 gene, while betaine treatment attenuated its expression along with the downregulation of inflammatory genes (NLRP3, TLR‐4, TNF‐α, and IL‐6) and fibrosis‐related genes (TGF‐β and Acta2) expression in Dox‐treated rats. These results showed that betaine has reno‐protective properties by reducing inflammatory and fibrotic mediators and enhancing antioxidant capacity in the renal tissue of rats treated with Dox. We believe betaine can be exploited as a dietary supplement to attenuate DIN.

Chitosan-functionalized bioplatforms and hydrogels in breast cancer: immunotherapy, phototherapy and clinical perspectives

Breast cancer is the most common and malignant tumor among women. Chitosan (CS)-based nanoparticles have been introduced into breast cancer therapy as a way to increase the targeted delivery of drugs and genes to the tumor site. CS nanostructures suppress tumorigenesis by enhancing both the targeted delivery of cargo (drug and gene) and its accumulation in tumor cells. The tumor cells internalize CS-based nanoparticles through endocytosis. Moreover, chitosan nanocarriers can also induce phototherapy-mediated tumor ablation. Smart and multifunctional types of CS nanoparticles, including pH-, light- and redox-responsive nanoparticles, can be used to improve the potential for breast cancer removal. In addition, the acceleration of immunotherapy by CS nanoparticles has also been achieved, and there is potential to develop CS-nanoparticle hydrogels that can be used to suppress tumorigenesis.

The functions and mechanisms of post-translational modification in protein regulators of RNA methylation: Current status and future perspectives

RNA methylation, an epigenetic modification that does not alter gene sequence, may be important to diverse biological processes. Protein regulators of RNA methylation include "writers," "erasers," and "readers," which respectively deposit, remove, and recognize methylated RNA. RNA methylation, particularly N6-methyladenosine (m6A), 5-methylcytosine (m5C), N3-methylcytosine (m3C), N1-methyladenosine (m1A) and N7-methylguanosine (m7G), has been suggested as disease therapeutic targets. Despite advances in the structure and pharmacology of RNA methylation regulators that have improved drug discovery, regulating these proteins by various post-translational modifications (PTMs) has received little attention. PTM modifies protein structure and function, affecting all aspects of normal biology and pathogenesis, including immunology, cell differentiation, DNA damage repair, and tumors. It is becoming evident that RNA methylation regulators are also regulated by diverse PTMs. PTM of RNA methylation regulators induces their covalent linkage to new functional groups, hence modifying their activity and function. Mass spectrometry has identified many PTMs on protein regulators of RNA methylation. In this review, we describe the functions and PTM of protein regulators of RNA methylation and summarize the recent advances in the regulatory mode of human disease and its underlying mechanisms.

CD24 May Serve as an Immunotherapy Target in Triple-Negative Breast Cancer by Regulating the Expression of PD-L1

PURPOSE

CD24 mediates a "don't eat me" signal to escape the immune environment. However, the correlation between CD24 and PD-L1 is unclear. This study aimed to assess if CD24 can serve as a target for immunotherapy of triple-negative breast cancer (TNBC).

METHODS

Data on CD24 expression in breast cancer were acquired using the Oncomine and UALCAN tools. The role of CD24 expression on the prognosis of patients with TNBC was assessed using Kaplan-Meier analyses. Subsequently, STRING and TISIDB databases were used to construct protein-protein interaction networks and to explore immune-related molecules regulated by CD24. Immunofluorescence and immunohistochemistry assays were conducted to validate CD24 and PD-L1 expression and tumor infiltration lymphocyte (TIL) level. Survival analysis was also performed to explore the effect of CD24 and PD-L1 expression and TIL level in patients with TNBC. ShRNA was also used to explore the regulation role of CD24 on PD-L1 expression.

RESULTS

CD24 expression was significantly higher in breast cancer than in normal tissues, with high expression being significantly associated with a worse prognosis. CD24 was found to be significantly regulated by chemokines, immunoinhibitors, immunostimulators and TILs. Furthermore, CD24 expression showed a significant positive correlation with PD-L1 expression and a negative correlation with TIL level. In association with PD-L1, CD24 was found to positively regulate lymphocyte costimulation, T cell costimulation, and leukocyte activation. Furthermore, CD24 and PD-L1 co-expression contributed to worse survival outcomes. In addition, CD24 expression was found to attenuate the positive effects of high-level TILs on the prognosis of patients with TNBC. CD24 can also regulate the expression of PD-L1 in TNBC cells.

CONCLUSION

CD24 may attenuate the positive effects of high TIL levels on survival and may facilitate the immune escape of TNBC by regulating PD-L1 expression. Thus, it is a potential target for immunotherapy in TNBC.

Effects of RNA methylation on Tumor angiogenesis and cancer progression

Tumor angiogenesis plays vital roles in the growth and metastasis of cancer. RNA methylation is one of the most common modifications and is widely observed in eukaryotes and prokaryotes. Accumulating studies have revealed that RNA methylation affects the occurrence and development of various tumors. In recent years, RNA methylation has been shown to play an important role in regulating tumor angiogenesis. In this review, we mainly elucidate the mechanisms and functions of RNA methylation on angiogenesis and progression in several cancers. We then shed light on the role of RNA methylation-associated factors and pathways in tumor angiogenesis. Finally, we describe the role of RNA methylation as potential biomarker and novel therapeutic target.