Effects of Knockdown of XPO5 by siRNA on the Biological Behavior of Head and Neck Cancer Cells.

Objectives/Hypothesis: Dysregulated expression of microRNAs (miRNAs) and dysregulation of the mechanisms that regulate them are associated with carcinogenesis. Exportin‐5 (XPO5), a member of the Karyopherin family, is responsible for the transfer of pre‐miRNAs from the nucleus to the cytoplasm. Despite the high oncogenic potential of XPO5 as a critical regulator of the biogenesis of miRNAs, its role in head and neck squamous cell carcinoma (HNSCC) biology has not been explained yet. Study Design: In‐vitro translational. Methods: The expression of XPO5 at the mRNA, protein, and intracellular level in SCC‐9, FaDu SCC‐90, and Detroit‐562 cell lines were evaluated with quantitative reverse transcription polymerase chain reaction, Western‐blot analysis, and immunofluorescence staining, respectively. The functional role of XPO5 in HNSCC was analyzed by silencing the gene expression with XPO5‐small interfering RNA (siRNA) in the in vitro model. Cell proliferation, migration capacity, and apoptosis in XPO5 knockdown HNSCC cell lines were evaluated by MTT, wound‐healing, and caspase‐3 assay, respectively. Results: Expression of XPO5 was determined to be upregulated at mRNA, protein, and intracellular level in metastatic cells compared to primary cells in HNSCC. XPO5 gene expression was knockdown by XPO5‐siRNA transfection, verifying that it was suppressed at the mRNA, protein, and intracellular level. Silencing XPO5 caused a decrease in cell proliferation, delay in wound healing, and increase in Caspase‐3 enzyme activity in HNSCC cell lines compared to control. Conclusions: This report is the first to describe the oncogenic role of XPO5 in HNSCC biology by in vitro experiments. Consequently, XPO5 can be used as a potential biomarker and therapeutic target molecule against the disease in the diagnosis‐treatment‐follow‐up of HNSCC. Level of Evidence: NA Laryngoscope, 132:569–577, 2022 [ABSTRACT FROM AUTHOR]