Theranostics 2021; 11(16):7640-7657. doi:10.7150/thno.61178

Research Paper

Silencing of METTL3 effectively hinders invasion and metastasis of prostate cancer cells

Yabing Chen1,2#, Chun Pan1,2#, Xiaotong Wang3, Dihui Xu1,2, Yuhan Ma1,2, Jianhang Hu1,2, Peilin Chen1,2, Zou Xiang4, Qiu Rao3✉, Xiaodong Han1,2✉

1. Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing 210093, China.
2. Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing 210093, China.
3. Department of Pathology, Jinling Hospital, Nanjing University School of Medicine, Nanjing 210002, China.
4. Department of Health Technology and Informatics, Faculty of Health and Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong China.
#These authors contributed equally to this study.

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Citation:
Chen Y, Pan C, Wang X, Xu D, Ma Y, Hu J, Chen P, Xiang Z, Rao Q, Han X. Silencing of METTL3 effectively hinders invasion and metastasis of prostate cancer cells. Theranostics 2021; 11(16):7640-7657. doi:10.7150/thno.61178. Available from https://www.thno.org/v11p7640.htm

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Abstract

Background: Since primary prostate cancer (PCa) can advance to the life-threatening metastatic PCa, exploring the molecular mechanisms underlying PCa metastasis is crucial for developing the novel targeted preventive strategies for decreasing the mortality of PCa. RNA N6-methyladenosine (m6A) is an emerging regulatory mechanism for gene expression and its specific roles in PCa progression remains elusive.

Methods: Western blotting, quantitative real-time PCR and immunohistochemical analyses were used to detect target gene expression in PCa cells in vitro and prostate tissues from patients. RNA immunoprecipitation was conducted to analyze the specific binding of mRNA to the target protein. Migration and invasion assays were used to assess the migratory capacities of cancer cells. The correlation between target gene expression and survival rate of PCa patients was analyzed based the TCGA database.

Results: We found that total RNA N6-methyladenosine (m6A) modification levels were markedly upregulated in human PCa tissues due to increased expression of methyltransferase like 3 (METTL3). Further studies revealed that the migratory and invasive capacities of PCa cells were markedly suppressed upon METTL3 knockdown. Mechanistically, METTL3 mediates m6A modification of USP4 mRNA at A2696, and m6A reader protein YTHDF2 binds to and induces degradation of USP4 mRNA by recruiting RNA-binding protein HNRNPD to the mRNA. Decrease of USP4 fails to remove the ubiquitin group from ELAVL1 protein, resulting in a reduction of ELAVL1 protein. Lastly, downregulation of ELAVL1 in turn increases ARHGDIA expression, promoting migration and invasion of PCa cells.

Conclusions: Our findings highlight the role of METTL3 in modulating invasion and metastasis of PCa cells, providing insight into promising therapeutic strategies for hindering PCa progressing to deadly metastases.

Keywords: METTL3, m6A, prostate cancer, metastasis, therapeutic strategies