METTL5-mediated 18S rRNA m6A modification promotes oncogenic mRNA translation and intrahepatic cholangiocarcinoma progression.

Intrahepatic cholangiocarcinoma (ICC) is a deadly cancer with rapid tumor progression. While hyperactive mRNA translation caused by mis-regulated mRNA or tRNA modifications promotes ICC development, the role of rRNA modifications remains elusive. Here, we found that 18S rRNA m6A modification and its methyltransferase METTL5 were aberrantly upregulated in ICC and associated with poorer survival (log rank test, p < 0.05). We further revealed the critical role of METTL5-mediated 18S rRNA m6A modification in regulation of ICC cell growth and metastasis using loss- and gain-of function assays in vitro and in vivo. The oncogenic function of METTL5 is corroborated using liver-specific knockout and overexpression ICC mouse models. Mechanistically, METTL5 depletion impairs 18S rRNA m6A modification that hampers ribosome synthesis and inhibits translation of G-quadruplex-containing mRNAs that are enriched in the transforming growth factor (TGF)-ß pathway. Our study uncovers the important role of METTL5-mediated 18S rRNA m6A modification in ICC and unravels the mechanism of rRNA m6A modification-mediated oncogenic mRNA translation control.

A GPX4-targeted photosensitizer to reverse hypoxia-induced inhibition of ferroptosis for non-small cell lung cancer therapy.

Ferroptosis therapy is gradually becoming a new strategy for the treatment of non-small cell lung cancer (NSCLC) because of its active iron metabolism. Because the hypoxic microenvironment in NSCLC inhibits ferroptosis heavily, the therapeutic effect of some ferroptosis inducers is severely limited. To address this issue, this work describes a promising photosensitizer ENBS-ML210 and its application against hypoxia of NSCLC treatment based on type I photodynamic therapy and glutathione peroxidase 4 (GPX4)-targeted ferroptosis. ENBS-ML210 can promote lipid peroxidation and reduce GPX4 expression by generating superoxide anion radicals under 660 nm light irradiation, which reverses the hypoxia-induced resistance of ferroptosis and effectively kills H1299 tumor cells. Finally, the excellent synergistic antitumor effects are confirmed both in vitro and in vivo. We firmly believe that this method will provide a new direction for the clinical treatment of NSCLC in the future.

A near-infrared GPX4 fluorescent probe for non-small cell lung cancer imaging.

Glutathione peroxidase 4 (GPX4) is overexpressed in non-small cell lung cancer (H1299) cells. In this work, a near-infrared fluorescent probe ENBO-ML210 was developed. In vitro and in vivo imaging results showed that ENBO-ML210 could target and visualize GPX4 in H1299 cells, exhibiting potential for the diagnosis of non-small lung cancer.

METTL1 promotes hepatocarcinogenesis via m7 G tRNA modification-dependent translation control.

BACKGROUND: N7 -methylguanosine (m7 G) modification is one of the most common transfer RNA (tRNA) modifications in humans. The precise function and molecular mechanism of m7 G tRNA modification in hepatocellular carcinoma (HCC) remain poorly understood. METHODS: The prognostic value and expression level of m7 G tRNA methyltransferase complex components methyltransferase-like protein-1 (METTL1) and WD repeat domain 4 (WDR4) in HCC were evaluated using clinical samples and TCGA data. The biological functions and mechanisms of m7 G tRNA modification in HCC progression were studied in vitro and in vivo using cell culture, xenograft model, knockin and knockout mouse models. The m7 G reduction and cleavage sequencing (TRAC-seq), polysome profiling and polyribosome-associated mRNA sequencing methods were used to study the levels of m7 G tRNA modification, tRNA expression and mRNA translation efficiency. RESULTS: The levels of METTL1 and WDR4 are elevated in HCC and associated with advanced tumour stages and poor patient survival. Functionally, silencing METTL1 or WDR4 inhibits HCC cell proliferation, migration and invasion, while forced expression of wild-type METTL1 but not its catalytic dead mutant promotes HCC progression. Knockdown of METTL1 reduces m7 G tRNA modification and decreases m7 G-modified tRNA expression in HCC cells. Mechanistically, METTL1-mediated tRNA m7 G modification promotes the translation of target mRNAs with higher frequencies of m7 G-related codons. Furthermore, in vivo studies with Mettl1 knockin and conditional knockout mice reveal the essential physiological function of Mettl1 in hepatocarcinogenesis using hydrodynamics transfection HCC model. CONCLUSIONS: Our work reveals new insights into the role of the misregulated tRNA modifications in liver cancer and provides molecular basis for HCC diagnosis and treatment.

N7-Methylguanosine tRNA modification enhances oncogenic mRNA translation and promotes intrahepatic cholangiocarcinoma progression.

Cancer cells selectively promote translation of specific oncogenic transcripts to facilitate cancer survival and progression, but the underlying mechanisms are poorly understood. Here, we find that N7-methylguanosine (m7G) tRNA modification and its methyltransferase complex components, METTL1 and WDR4, are significantly upregulated in intrahepatic cholangiocarcinoma (ICC) and associated with poor prognosis. We further reveal the critical role of METTL1/WDR4 in promoting ICC cell survival and progression using loss- and gain-of-function assays in vitro and in vivo. Mechanistically, m7G tRNA modification selectively regulates the translation of oncogenic transcripts, including cell-cycle and epidermal growth factor receptor (EGFR) pathway genes, in m7G-tRNA-decoded codon-frequency-dependent mechanisms. Moreover, using overexpression and knockout mouse models, we demonstrate the crucial oncogenic function of Mettl1-mediated m7G tRNA modification in promoting ICC tumorigenesis and progression in vivo. Our study uncovers the important physiological function and mechanism of METTL1-mediated m7G tRNA modification in the regulation of oncogenic mRNA translation and cancer progression.

Downregulation of microRNA-21-5p from macrophages-derived exosomes represses ventricular remodeling after myocardial infarction via inhibiting tissue inhibitors of metalloproteinase 3.

OBJECTIVE: Exosomes are known to transfer microRNAs (miRNAs) to affect the progression of human diseases. We aim to explore the role of M1 macrophages-derived exosomes (M1 exosomes) conveying miR-21-5p in ventricular remodeling in mice with myocardial infarction (MI) by regulating tissue inhibitors of metalloproteinase 3 (TIMP3). METHODS: Macrophages were isolated and co-cultured with miR-21-5p antagomir to extract the exosomes. The modeled mice were injected with relative exosomes to investigate their roles in the cardiac function, pathology of myocardial tissue, myocardial fibrosis, cardiomyocyte apoptosis and ventricular remodeling in MI mice. The expression of miR-21-5p and TIMP3 was detected and their targeting relationship was analyzed. RESULTS: MiR-21-5p was upregulated while TIMP3 was downregulated in MI mouse myocardial tissues. M1 exosomes impaired cardiac function, aggravated pathology of myocardial tissue, myocardial fibrosis and ventricular remodeling, and promoted cardiomyocyte apoptosis in MI mice. M1 exosomes containing miR-21-5p antagomir alleviated the above alterations, while the role of exosomes containing miR-21-5p antagomir was reversed by silencing TIMP3. TIMP3 was targeted by miR-21-5p. CONCLUSION: Downregulation of miR-21-5p from macrophages-derived exosomes suppresses ventricular remodeling after MI via inhibiting TIMP3.