Human ALKBH3-induced m¹A demethylation increases the CSF-1 mRNA stability in breast and ovarian cancer cells

In ovarian and breast cancers, the actions of the cytokine CSF-1 lead to poor prognosis. CSF-1 expression can be regulated post-transcriptionally. RNA methylation is another layer of posttranscriptional regulation. The methylation of N¹ atom of adenine (m¹A) results in a conformational change of RNA which regulates translational efficiency. Our study indicates that the m¹A is also involved in the CSF-1 mRNA decay. The alteration of ALKBH3 expression, an m¹A demethylase, regulates the CSF-1 mRNA stability. Demethylation of m¹A by ALKBH3 increases the half-life of CSF-1 mRNA without affecting the translation efficiency. The m¹A in CSF-1 mRNA is mapped in the 5′UTR near the translation initiation site. YTHDF2, a known m⁶A reader which interacts with the CCR4-NOT deadenylation complex, is not the reader of m¹A-containing CSF-1 mRNA. Overexpression of ALKBH3 increases CSF-1 expression and the degree of cancer cell invasiveness without affecting cell proliferation or migration. Collectively, we showed that CSF-1 mRNA decay can be regulated at an epigenetic level, and that alteration of the N¹‑methylation status leads to phenotypic changes in cancer cell behavior.