N⁶-Methyladenosine Modification of ANLN Enhances Hepatocellular Carcinoma Bone Metastasis

Bones are categorized as the second most prevalent location of extra-hepatic metastasis in Hepatocellular Carcinoma (HCC), which is linked to an extremely poor prognosis due to limited therapeutic options. N⁶-methyladenosine (m⁶A) is a prominent modification involved in HCC, but the exact mechanisms on how m⁶A modifications induce HCC bone metastases (BM) remain unclear. The key modulators responsible for the abundant m⁶A RNA modification-induced HCC BM was found to be the METTL3 and YTHDF1. The expression of Anillin actin-binding protein (ANLN) was dramatically higher in HCC with BM tissues, and its messenger RNA (mRNA) stability was enhanced via m⁶A epitranscriptomic regulation by METTL3 and YTHDF1. High METTL3 and YTHDF1 expression along with nuclear ANLN protein was clinically correlated with BM in HCC patients. Furthermore, HCC BM was attributed to over-expression of nuclear ANLN forming a transcriptional complex with SP1 which enhanced KIF2C transcriptional activity to activate the mTORC1 pathway, therefore increased the expression of RANKL and disproportionated RANKL-OPG expression in bone microenvironment leading to malignant neoplasms invade bone tissue. In addition, inhibition of ANLN m⁶A modification by DZNeP attenuated HCC BM. This data provides meaningful understanding of the modulation and association of m⁶A epitranscriptomic-regulated BM in HCC, and moreover, defines potentially valuable therapeutic targets.