MiR-218-5p/EGFR Signaling in Arsenic-Induced Carcinogenesis

SIMPLE SUMMARY: EGFR upregulation plays an important role in lung cancer as a well-established target for lung cancer therapy. However, the role and mechanism of EGFR upregulation due to chronic arsenic exposure remain to be elucidated. Here, we demonstrated that miR-218-5p was dramatically downregulated in arsenic-induced transformed (As-T) cells. It served as a tumor suppressor to suppress cell proliferation, migration, colony formation, and tube formation, and inhibit tumor growth and angiogenesis by directly targeting EGFR. Our results suggest that the 218-5p/EGFR signaling pathway may be a potential therapeutic target for the treatment of lung cancer induced by chronic arsenic exposure. ABSTRACT: Background: Arsenic is a well-known carcinogen inducing lung, skin, bladder, and liver cancer. Abnormal epidermal growth factor receptor (EGFR) expression is common in lung cancer; it is involved in cancer initiation, development, metastasis, and treatment resistance. However, the underlying mechanism for arsenic-inducing EGFR upregulation remains unclear. Methods: RT-PCR and immunoblotting assays were used to detect the levels of miR-218-5p and EGFR expression. The Luciferase assay was used to test the transcriptional activity of EGFR mediated by miR-218-5p. Cell proliferation, colony formation, wound healing, migration assays, tube formation assays, and tumor growth assays were used to study the function of miR-218-5p/EGFR signaling. Results: EGFR and miR-218-5p were dramatically upregulated and downregulated in arsenic-induced transformed (As-T) cells, respectively. MiR-218-5p acted as a tumor suppressor to inhibit cell proliferation, migration, colony formation, tube formation, tumor growth, and angiogenesis. Furthermore, miR-218-5p directly targeted EGFR by binding to its 3′-untranslated region (UTR). Finally, miR-218-5p exerted its antitumor effect by inhibiting its direct target, EGFR. Conclusion: Our study highlights the vital role of the miR-218-5p/EGFR signaling pathway in arsenic-induced carcinogenesis and angiogenesis, which may be helpful for the treatment of lung cancer induced by chronic arsenic exposure in the future.