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METTL3 Promotes Tumorigenesis and Metastasis through BMI1 m⁶A Methylation in Oral Squamous Cell Carcinoma.

ABSTRACT: RNA modification plays an essential function in regulating gene expression and diverse biological processes. RNA modification enzyme methyltransferase-like 3 (METTL3) affects tumor progression by regulating the N⁶-methyladenosine (m⁶A) modification in the mRNAs of critical oncogenes or tumor suppressors, but its effect in oral squamous cell carcinoma (OSCC) remains unknown. In this study, we revealed that METTL3 was consistently upregulated in two OSCC cohorts, and high METTL3 expression was associated with poor prognosis. Functionally, cell proliferation, self-renewal, migration, and invasion ability in vitro and tumor growth and metastasis in vivo were decreased after METTL3 knockdown in OSCC cells. In contrast, the opposite results were obtained after METTL3 overexpression. In addition, the results obtained with the Mettl3 genetically modified mouse model validated the essential role of Mettl3 in chemical-induced oral carcinogenesis. In mechanism, methylated RNA immunoprecipitation sequencing (MeRIP-seq), MeRIP-quantitative real-time PCR, and luciferase reporter and mutagenesis assays identified that METTL3 mediates the m⁶A modification in the 3' UTR of BMI1 mRNA. METTL3 promotes BMI1 translation in OSCC under the cooperation with m⁶A reader IGF2BP1. Our findings revealed that METTL3 promotes OSCC proliferation and metastasis through BMI1 m⁶A methylation, suggesting that the METTL3-m⁶A-BMI1 axis may serve as a prognostic biomarker or therapeutic target in patients with OSCC.

SUBMITTER: Liu L

PROVIDER: S-EPMC7544972 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Oral squamous cell carcinoma (OSCC) is the most common malignancy of the head and neck worldwide. Dysbiosis of the microbiome has increasingly been linked to the development of different kinds of cancer. Applying 16S rRNA gene sequence analysis and metatranscriptomic analyses, we characterized the longitudinal changes in the profiles and the function of the oral microbiome in a 4-nitroquinoline-1-oxide (4-NQO)-induced model of OSCC in gnotobiotic mice. We characterized the dynamics of the oral microbiome in this model using two different microbiome inocula: one from healthy mice and the other from mice bearing a 4-NQO-induced tumor. Mice colonized with different oral microbiomes and exposed to 4-NQO had increased tumor numbers and sizes compared to controls exposed to 4-NQO but lacking a microbiome. We observed an overall increase in diversity in the tumorigenic samples compared to that in the nontumor group not exposed to 4-NQO. Despite the variability in community dynamics, specific patterns emerged during the progression of the disease. In the two groups that were inoculated with the OSCC-associated microbiome, we observed opposite profiles of abundance in Parabacteroides and Corynebacterium While the percentage of Parabacteroides bacteria decreased in the control group, it increased in the OSCC group, and the opposite was observed for Corynebacterium The metatranscriptomic analysis revealed overexpression of the same metabolic signatures associated with OSCC regardless of the community profile. These included nitrogen transport, response to stress, interspecies interactions, Wnt pathway modulation, and amino acid and lipid biosynthesis. Thus, these results seem to suggest that certain collective physiological activities are critical for microbiome-mediated OSCC progression.IMPORTANCE There is growing evidence that changes in the microbiome are associated with carcinogenesis. To date, no consistent oral microbiome composition associated with OSCC has been identified. Longitudinal and functional studies like the study presented here should yield a better understanding of the role that the oral microbiome plays in OSCC. Our findings, obtained using a germ-free mouse model, indicate that the presence of different oral microbiomes enhances tumorigenesis and increases the final number of tumors in mice. By studying community-wide expression profiles, we found that regardless of the phylogenetic composition of the microbiome, the same metabolic activities were consistently associated with OSCC. Therefore, due to the functional redundancy of the microbiome, the critical element in explaining the contribution of the microbiota in OSCC is the collective physiological activity of the community, thus accounting for the previous inability to identify a consensus community profile or etiologic agents for OSCC.

Project description:As the key enzyme of the N6-methyladenosine (m6A) in eukaryotic messenger RNA, METTL3 plays an important role in tumor progression, but the exact mechanism by which METTL3 controls oral squamous cell carcinoma (OSCC) progression remains unclear. In this study, METTL3 expression in OSCC samples was analyzed by qPCR and immunohistochemistry. The effects of METTL3 suppression on OSCC cell lines were measured by CCK-8, Ki67 flow cytometry analysis, invasion transwell and wound healing assays. MeRIP-seq and RNA-seq analyses were performed to explore target gene of METTL3. RIP-qPCR and RNA stability assays were performed to explore the mechanism by which METTL3 regulated the target genes. Triptolide was used to evaluate its specific treatment effects on METTL3 in OSCC cells. BALB/c nude mice were used to establish orthotopic and subcutaneous xenograft models to verify the in vitro results. The results showed that METTL3 was upregulated in OSCC tissues compared with OSCC adjacent normal tissues, and its expression was associated with T stage, lymphatic metastasis and prognosis. METTL3 suppression impaired OSCC cells proliferation, invasion, and migration. MeRIP-seq and RNA-seq analysis identified that SLC7A11 mRNA was the m6A target of METTL3, which was verified by meRIP-qPCR, qPCR and western blot. METTL3 depletion decreased the stability of SLC7A11 mRNA, and IGF2BP2 as m6A reader was involved in this process. Moreover, METTL3 knockdown attenuated the binding between SLC7A11 mRNA and IGF2BP2, finally leading to accelerate SLC7A11 mRNA degradation. Triptolide inhibited METTL3-mediated SLC7A11 expression, thus suppressing malignancy of OSCC cells. In conclusion, the new finding of the manuscript is that METTL3 enhances the mRNA stability of SLC7A11 via m6A-mediated binding of IGF2BP2, which thus promotes OSCC progression, and triptolide inhibits OSCC by suppressing METTL3-SLC7A11 axis. Triptolide has a potential to be as an effective anti-OSCC drug targeted to METTL3.

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METTL3 Promotes Tumorigenesis and Metastasis through BMI1 m⁶A Methylation in Oral Squamous Cell Carcinoma.

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Dataset Information

METTL3 Promotes Tumorigenesis and Metastasis through BMI1 m6A Methylation in Oral Squamous Cell Carcinoma.

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OmicsDI is part of the ELIXIR infrastructure

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METTL3 Promotes Tumorigenesis and Metastasis through BMI1 m⁶A Methylation in Oral Squamous Cell Carcinoma.