Abstract:Background and Aims Invasion and metastasis are major causes of poor prognosis in hepatocellular carcinoma (HCC). Although homeobox A11 (HOXA11) has been implicated in various malignancies, its biological role and underlying mechanisms in HCC remain unclear. This study investigated the epigenetic regulation of HOXA11 and its effects on HCC progression and metastasis.Methods Eleven paired HCC and adjacent non-tumor tissues were collected. HOXA11 expression and promoter methylation were examined using Western blotting, immunohistochemistry, and bisulfite sequencing PCR (BSP). Decitabine (DAC) was used for demethylation treatment. Stable HOXA11 knockdown and overexpression cell lines were established. Cell proliferation, migration, and invasion were assessed by CCK-8 and Transwell assays. Expression of the TGF-β/Smad pathway- and epithelial-mesenchymal transition (EMT)-related proteins was analyzed by Western blotting. TGF-β1 rescue experiments were performed to verify the underlying mechanism. A nude mouse lung metastasis model was established to evaluate the effect of HOXA11 on metastatic potential in vivo.Results HOXA11 expression was significantly decreased in HCC tissues, whereas promoter methylation was significantly increased compared with adjacent tissues (both P<0.05). DAC treatment reduced promoter methylation and restored HOXA11 expression. HOXA11 knockdown significantly enhanced HCC cell proliferation, migration, and invasion, whereas HOXA11 overexpression exerted the opposite effects (all P<0.05). Mechanistically, HOXA11 negatively regulated the TGF-β/Smad signaling pathway and suppressed EMT, as evidenced by increased E-cadherin expression and decreased expression of Snail, N-cadherin, vimentin, and fibronectin. TGF-β1 rescue experiments further demonstrated that HOXA11 overexpression partially antagonized TGF-β1-induced Smad phosphorylation and EMT progression. Clinical analyses confirmed significant associations between low HOXA11 expression, activation of the TGF-β/Smad pathway, and EMT-related alterations. In vivo, HOXA11 overexpression significantly reduced pulmonary metastatic burden (P<0.05).Conclusion HOXA11 is epigenetically silenced through promoter hypermethylation in HCC. By negatively regulating the TGF-β/Smad signaling pathway and suppressing EMT, HOXA11 inhibits HCC invasion and metastasis. These findings suggest that HOXA11 may serve as a potential therapeutic target for epigenetic and anti-metastatic intervention in HCC.