Downregulation of N6-methyladenosine-modified LINC00641 promotes EMT, but provides a ferroptotic vulnerability in lung cancer

Pingxiao pian attenuate invasiveness and proliferation of lung adenocarcinoma through regulating miR-29b-3p/TGF-β1/Smad/EMT pathway

INTRODUCTION

Lung cancer is a highly prevalent and deadly disease worldwide, causing over 1.2 million deaths each year. Pingxiao Pian (PXP) tablets, a Chinese traditional medicine, have been widely applied in the treatment of lung cancer. However, the mechanism underlying therapeutic effects of PXP tablets remains undisclosed.

METHODS

A549 human LUAD cell line was utilized for in vitro experiments. Transfection of miR-29b mimic was performed using Lipofectamine 3000. PXP was purchased and dissolved into PBS and drinking water after carefully removing the outer coating. Dual-luciferase reporter assay was conducted to assess the regulatory effect of miR-29b on TGF-β1. The protein levels of epithelial-mesenchymal transition (EMT) markers and activation of TGF-β1 pathway were characterized using immunoblotting analysis.

RESULTS

PXP reduced the invasiveness and proliferation of LUAD cells by increasing miR-29b-3p expression in vitro. Overexpression of miR-29b-3p resulted in decreased cell proliferation and invasiveness, while silencing of miR-29b-3p in the A549 cells displayed the opposite effect. Moreover, PXP treatment reversed the increased cell proliferating rate triggered by miR-29b-3p silencing. Additionally, PXP was found to hamper EMT occurrence in A549 cells by regulating miR-29b-3p and reduce expression of N-cad and vimentin. Overexpression of miR-29b-3p blocked the phosphorylation of Smad2/3 and decreased TGF-β1 expression. Luciferase assay results indicated that miR-29b-3p directly regulated TGF-β1 expression. In vivo tumor formation experiments confirmed the tumor-reducing effects of PXP and the role of miR-29b in tumor progression. PXP treatment decreased tumor size and weight via regulating miR-29b-3p.

CONCLUSION

Our study suggests that PXP exerts anti-tumor effects in LUAD through the regulation of miR-29b and the inhibition of EMT via the TGF-β1/Smad2/3 pathway.

Neutrophil extracellular traps promote growth of lung adenocarcinoma by mediating the stability of m6A-mediated SLC2A3 mRNA-induced ferroptosis resistance and CD8(+) T cell inhibition

To investigate the potential mechanisms underlying neutrophil extracellular traps (NETs) confer ferroptosis resistance and CD8(+) T cell inhibition in lung adenocarcinoma (LUAD). By the intravenous injection of LLC cells into the tail vein, a LUAD mouse model was created. Phorbol-12-myristate-13-acetate (PMA) stimulated neutrophils to facilitate NETs formation and combined with NETs inhibitor DNase I to explore NETs mechanism on LLC cell proliferation, migration, ferroptosis resistance, and CD8(+) T cell activity. CitH3, myeloperoxidase (MPO), cell-free DNA, and MPO-DNA levels in LUAD were increased, indicating an increase in NETs formation in LUAD. PMA promoted NETs formation in tumours of mice, increased the number of CD3(+)CD4(+) T cells, decreased perforin, granzyme A, granzyme B, IFNγ, and TNF-α levels, and promoted LUAD growth and the number of lung tumour nodules, indicating that PMA promoted NETs formation, reduced the activity of CD8(+)T cells, and promoted LUAD growth. DNase I partially reversed the effects of PMA. NETs promoted LLC cell proliferation and migration, while DNase I reversed NETs effects. Erastin inhibited LLC cell proliferation and migration and promoted ferroptosis. NETs partially reversed Erastin effects. Further results showed that NETs promoted LLC cell proliferation and migration and inhibited ferroptosis by promoting YTHDF2-mediated SLC2A3 mRNA degradation. Sh-YTHDF2 partially reversed the effect of NETs on LLC cells, whereas si-SLC2A3 partially reversed sh-YTHDF2 effects on LLC cells. In addition, NETs inhibited LLC cell ferroptosis by inhibiting CD8(+) T cell activity. Sh-YTHDF2 and DNase I inhibited NETs formation in tumours, increased the activity of CD8(+) T cells and inhibited LUAD growth. Our results suggested that NETs promoted the growth of LUAD through inhibiting ferroptosis and CD8(+) T cell activity by promoting YTHDF2-mediated SLC2A3 mRNA degradation.

N6-methyladenosine RNA modification regulates the transcription of SLC7A11 through KDM6B and GATA3 to modulate ferroptosis

BACKGROUND

Recent studies indicate that N6-methyladenosine (m6A) RNA modification may regulate ferroptosis in cancer cells, while its molecular mechanisms require further investigation.

METHODS

Liquid Chromatography-Tandem Mass Spectrometry (HPLC/MS/MS) was used to detect changes in m6A levels in cells. Transmission electron microscopy and flow cytometry were used to detect mitochondrial reactive oxygen species (ROS). RNA sequencing (RNA-seq) was employed to analyze the factors regulating ferroptosis. Chromatin immunoprecipitation (ChIP) was used to assess the binding of regulatory factors to the SLC7A11 promoter, and a Dual-Luciferase reporter assay measured promoter activity of SLC7A11. The dm6ACRISPR system was utilized for the demethylation of specific transcripts. The Cancer Genome Atlas Program (TCGA) database and immunohistochemistry validated the role of the METTL3/SLC7A11 axis in cancer progression.

RESULTS

The m6A methyltransferase METTL3 was upregulated during cancer cell ferroptosis and facilitated erastin-induced ferroptosis by enhancing mitochondrial ROS. Mechanistic studies showed that METTL3 negatively regulated the transcription and promoter activity of SLC7A11. Specifically, METTL3 induced H3K27 trimethylation of the SLC7A11 promoter by suppressing the mRNA stability of H3K27 demethylases KDM6B. Furthermore, METTL3 suppressed the expression of GATA3, which regulated SLC7A11 transcription by binding to the putative site at - 597 to - 590 of the SLC7A11 promoter. METTL3 decreased the precursor mRNA stability of GATA3 through m6A/YTHDF2-dependent recruitment of the 3'-5' exoribonuclease Dis3L2. Targeted demethylation of KDM6B and GATA3 m6A using the dm6ACRISPR system significantly increased the expression of SLC7A11. Moreover, the transcription factor YY1 was responsible for erastin-induced upregulation of METTL3 by binding to its promoter-proximal site. In vivo and clinical data supported the positive roles of the METTL3/SLC7A11 axis in tumor growth and progression.

CONCLUSIONS

METTL3 regulated the transcription of SLC7A11 through GATA3 and KDM6B to modulate ferroptosis in an m6A-dependent manner. This study provides a novel potential strategy and experimental support for the future treatment of cancer.

The regulatory mechanisms of N6-methyladenosine modification in ferroptosis and its implications in disease pathogenesis

HEADING AIMS

Based on the current knowledge of the molecular mechanisms by which m6A influences ferroptosis, our objective is to underscore the intricate and interdependent relationships between m6A and the principal regulatory pathways of ferroptosis, as well as other molecules, emphasizing its relevance to diseases associated with this cell death mode.

MATERIALS AND METHODS

We conducted a literature search using the keywords "m6A and ferroptosis" across PubMed, Web of Science, and Medline. The search was limited to English-language publications from 2017 to 2024. Retrieved articles were managed using Endnote software. Two authors independently screened the search results and reviewed the full texts of selected articles.

KEY FINDINGS

Abnormal m6A levels are often identified as critical regulators of ferroptosis. Specifically, "writers", "readers" and "erasers" that dynamically modulate m6A function regulate various pathways in ferroptosis including iron metabolism, lipid metabolism and antioxidant system. Additionally, we provide an overview of the role of m6A-mediated ferroptosis in multiple diseases and summarize the potential applications of m6A-mediated ferroptosis, including its use as a therapeutic target for diseases and as diagnostic as well as prognostic biomarkers.

SIGNIFICANCE

N6-methyladenosine (m6A) modification, a prevalent RNA modification in eukaryotic cells, is crucial in regulating various aspects of RNA metabolism. Notably, accumulating evidence has implicated m6A modification in ferroptosis, a form of iron-dependent cell death characterized by elevated iron levels and lipid peroxide accumulation. Overall, this review sheds light on the potential diagnostic and therapeutic applications of m6A regulators in addressing conditions associated with ferroptosis.

Iron homeostasis and ferroptosis in human diseases: mechanisms and therapeutic prospects

Iron, an essential mineral in the body, is involved in numerous physiological processes, making the maintenance of iron homeostasis crucial for overall health. Both iron overload and deficiency can cause various disorders and human diseases. Ferroptosis, a form of cell death dependent on iron, is characterized by the extensive peroxidation of lipids. Unlike other kinds of classical unprogrammed cell death, ferroptosis is primarily linked to disruptions in iron metabolism, lipid peroxidation, and antioxidant system imbalance. Ferroptosis is regulated through transcription, translation, and post-translational modifications, which affect cellular sensitivity to ferroptosis. Over the past decade or so, numerous diseases have been linked to ferroptosis as part of their etiology, including cancers, metabolic disorders, autoimmune diseases, central nervous system diseases, cardiovascular diseases, and musculoskeletal diseases. Ferroptosis-related proteins have become attractive targets for many major human diseases that are currently incurable, and some ferroptosis regulators have shown therapeutic effects in clinical trials although further validation of their clinical potential is needed. Therefore, in-depth analysis of ferroptosis and its potential molecular mechanisms in human diseases may offer additional strategies for clinical prevention and treatment. In this review, we discuss the physiological significance of iron homeostasis in the body, the potential contribution of ferroptosis to the etiology and development of human diseases, along with the evidence supporting targeting ferroptosis as a therapeutic approach. Importantly, we evaluate recent potential therapeutic targets and promising interventions, providing guidance for future targeted treatment therapies against human diseases.

ATF1 promotes ferroptosis resistance in lung cancer through enhancing mRNA stability of PROM2

BACKGROUND

Ferroptotic proteins are promising therapeutic targets for lung cancer. The PROM2 is upregulated in lung cancer and known to suppress ferroptosis. This study examined the molecular mechanisms for PROM2-induced ferroptosis resistance in lung cancer.

METHODS

Ferroptosis in lung cancer was assessed by iron kit, and transmission electron microscopy was applied to observe the changes in mitochondrial morphology. BODIPY™ was applied to test the lipid ROS, and MeRIP was performed to test the m6A modification of PROM2. RIP assay was employed for confirming the binding between METTL3 and PROM2. In addition, dual luciferase assay was employed for exploring the transcriptional regulation of ATF1 to METTL3, and the binding relation between ATF1 and METTL3 promoter region was explored by ChIP assay.

RESULTS

Expression levels of PROM2 were significantly higher in lung cancer cell lines than a noncancerous control line, and PROM2 knockdown significantly reduced both cancer cell viability and proliferation rate. In addition, PROM2 knockdown reduced xenograft tumor growth and exacerbated erastin-induced ferroptosis. Compared to PROM2 mRNA from control cells, transcripts in lung cancer cells exhibited enhanced m6A levels, and showed greater binding with METTL3. Further, ATF1 upregulated METTL3 transcription, thereby stabilizing PROM2 mRNA and increasing ferroptosis resistance.

CONCLUSION

ATF1 could promote ferroptosis resistance in lung cancer through enhancing mRNA stability of PROM2. Thus, our work might shed novel insights on discovering therapeutic strategy for lung cancer.

Examining the evidence for mutual modulation between m6A modification and circular RNAs: current knowledge and future prospects

The resistance of cancer cells to treatment significantly impedes the success of therapy, leading to the recurrence of various types of cancers. Understanding the specific mechanisms of therapy resistance may offer novel approaches for alleviating drug resistance in cancer. Recent research has shown a reciprocal relationship between circular RNAs (circRNAs) and N6-methyladenosine (m6A) modification, and their interaction can affect the resistance and sensitivity of cancer therapy. This review aims to summarize the latest developments in the m6A modification of circRNAs and their importance in regulating therapy resistance in cancer. Furthermore, we explore their mutual interaction and exact mechanisms and provide insights into potential future approaches for reversing cancer resistance.

Ferroptosis: a critical mechanism of N6-methyladenosine modification involved in carcinogenesis and tumor progression

Ferroptosis is an iron-dependent regulatory cell necrosis induced by iron overload and lipid peroxidation. It occurs when multiple redox-active enzymes are ectopically expressed or show abnormal function. Hence, the precise regulation of ferroptosis-related molecules is mediated across multiple levels, including transcriptional, posttranscriptional, translational, and epigenetic levels. N6-methyladenosine (m6A) is a highly evolutionarily conserved epigenetic modification in mammals. The m6A modification is commonly linked to tumor proliferation, progression, and therapy resistance because it is involved in RNA metabolic processes. Intriguingly, accumulating evidence suggests that dysregulated ferroptosis caused by the m6A modification drives tumor development. In this review, we summarized the roles of m6A regulators in ferroptosis-mediated malignant tumor progression and outlined the m6A regulatory mechanism involved in ferroptosis pathways. We also analyzed the potential value and application strategies of targeting m6A/ferroptosis pathway in the clinical diagnosis and therapy of tumors.

ALKBH5 promotes the development of lung adenocarcinoma by regulating the polarization of M2 macrophages through CDCA4

OBJECTIVE

Lung adenocarcinoma (LUAD) is the most common subtype of lung cancer, with high morbidity and mortality. N6-methyladenosine (m6A) is an important regulator of LUAD progression. Here, we investigated the potential biological functions of ALKBH5 (a m6A demethylated enzyme) and cell division cycle associated protein 4 (CDCA4) in the progression of LUAD.

METHODS

The expressions of CDCA4, METTL3, ALKBH5, FTO, YTHDC2 and YTHDC1 mRNA and proteins in LUAD and adjacent tissues, as well as NCI-H1299 and NCI-H157 cells were detected by RT-qPCR and western blot. Meanwhile, the role of ALKBH5 and CDCA4 in macrophage polarization was explored through tumor formation in Lewis lung carcinoma (LLC) mice and the co-culture system of NCI-H1299 and NCI-H157/THP-1 cells. Cell characterization was further analyzed. The expression of Ki-67 in tumor tissue was tested by immunohistochemistry. The scale of M1 and M2 macrophages was determined by flow cytometry.

RESULTS

CDCA4 was significantly overexpressed in NCI-H1299 and NCI-H157 cell lines compared with BEAS-2B cells. The fold enrichment of CDCA4 m6A level in the overexpression (oe)-METTL3 or short hairpin (sh)-ALKBH5 cells was enhanced. Overexpression of CDCA4 promoted the cell viability, proliferation and migration, and inhibited apoptosis, which was reversed by sh-ALKBH5 intervention. Overexpression of YTHDC2 (not YTHDC1) inhibited the effect of CDCA4 on sh-ALKBH5 cells. sh-CDCA4 inhibited tumor growth and weight of LLC cells in mice, and promoted M1/M2 ratio in LLC mice and NCI-H1299/THP-1 and NCI-H157/THP-1 co-culture systems. Oe-CDCA4 promoted the volume and weight of tumor and inhibited the M1/M2 ratio of tumor tissue in LLC mice, but was reversed by sh-ALKBH5 intervention.

CONCLUSION

m6A demethylase ALKBH5 promotes the development of LUAD through CDCA4 regulation of malignant characterization and M1/M2 macrophage polarization.

METTL3 suppresses invasion of lung cancer via SH3BP5 m6A modification

The metastasis of lung cancer poses a major clinical challenge, and m6A modification has been implicated in regulating the invasive capabilities of tumor cells. However, the mechanisms underlying m6A modification in lung cancer metastasis are not well understood. This study aims to explore the biological functions and molecular mechanisms of methyltransferase-like 3 (METTL3) in lung cancer. In this study, METTL3 were found to be downregulated in lung cancer tissues. Functionally, METTL3 inhibited the migration and invasion abilities of lung cancer cells in vitro. Furthermore, SH3 domain binding protein 5 (SH3BP5) was identified as a downstream target of METTL3. Overexpression of SH3BP5 suppressed the invasive capacity of lung cancer cells, and this regulation was m6A-dependent. Finally, we discovered that YTH N6-methyladenosine RNA binding protein F1 (YTHDF1) mediated stability is responsible for maintaining the m6A modification of SH3BP5 mRNA. Overall, our study provides insights into the critical role of METTL3-mediated m6A modification and m6A-dependent regulatory mechanisms in the progression of human lung cancer. We demonstrated that METTL3 regulates the mRNA stability of SH3BP5 in a YTHDF1-dependent manner, thereby impacting the invasive capacity of lung cancer cells.