CARD9 downregulation suppresses the growth of oral squamous cell carcinoma by regulating NF-κB.

OBJECTIVE

To discover the expression pattern and potential underlying mechanism of the caspase recruitment domain-containing protein 9 (CARD9) in oral squamous cell carcinoma (OSCC).

METHODS

Caspase recruitment domain-containing protein 9 expression was detected by qRT-PCR and Western blot in OSCC tissues and cells, and OSCC (CGHNC9 and OECM-1) cell lines were divided into control, NC siRNA, and CARD9 siRNA groups. Then, MTT, flow cytometry, wound-healing, and Transwell assays were carried out to determine the changes in cellular biological characteristics. Immunoblot assay was performed for the expressions of NF-κB pathway. Finally, we constructed the xenograft models in nude mice to validate the in vivo effect of CARD9 siRNA on OSCC cell growth.

RESULTS

Caspase recruitment domain-containing protein 9 was upregulated in both OSCC tissues and cells, exhibiting a close relation with major clinicopathological features of OSCC patients. Transfection of CARD9 siRNA inhibited the proliferation, migration, and invasion of OSCC cells with the enhanced cell apoptosis, and meanwhile, CARD9, p-p65/p65, p-IKKα/IKKα, and p-IkBα/IkBα were downregulated. The tumor formation assay on nude mice also suggested that CARD9 siRNA might block the in vivo growth of OSCC cells.

CONCLUSION

Caspase recruitment domain-containing protein 9 suppression results in the upregulation of NF-κB pathway with suppressed proliferation, migration, and invasion of OSCC cells and facilitates the apoptosis.