ATOH8 overexpression inhibits the tumor progression and monocyte chemotaxis in hepatocellular carcinoma.

Objective: ATOH8 is reported to be associated with the progression of many tumors; however, there are remaining controversies. The aim of this study is to explore the role of ATOH8 in hepatocellular carcinoma (HCC) and its effect on monocyte chemotaxis.

Methods: Bioinformatics analysis was performed based on the LIHC data in GEPIA and LinkedOmic. Fresh human liver cancer and adjacent nontumor tissue specimens were collected at the Shanghai Public Health Clinical Center. qRT-PCR was performed to determine the transcript level, and western blot analysis and ELISA were used to detect protein expression. CCK8, colony formation, wound-healing, Transwell migration and invasion assays were performed to examine cell proliferation, migration and invasion. An HCC xenograft mouse model was used to determine oncogenicity in vivo. Cell apoptosis and related markers were detected by flow cytometry. Additionally, chemotaxis was assessed by the Transwell migration assay.

Results: ATOH8 expression is downregulated in HCC tissue and hepatoma cell lines. High expression of ATOH8 predicts a favorable prognosis. Overexpression of ATOH8 in liver cancer cells inhibits proliferation, migration and invasion in vitro, and tumor progression in nude mice. Knockdown of ATOH8 promotes proliferation of Huh7 and EMT-related proteins. Overexpression of ATOH8 increases chemosensitivity to 5-FU, which is probably caused by inhibiting the phosphorylation of AKT (Ser473). Furthermore, overexpression of ATOH8 in Huh7 reduced MCP1 to inhibit chemotactic THP-1, and promoted antitumor inflammatory cytokine (TNF-α and IFN-γ) secretion in monocytes.

Conclusion: In addition to the intrinsic oncosuppressive function of ATOH8 in the liver, ATOH8 may modulate the microenvironment to create an immune activation state. This may partly be attributed to ATOH8 inhibition of the monocyte recruitment via suppressing MCP1 expression so as to promote antitumor inflammatory cytokine secretion in monocytes.