关键词: 鼻咽癌, CKMT1A, DDX6, 细胞增殖, 细胞迁移

Abstract:

Background and purpose: DDX is an adenosine triphosphate (ATP)-dependent RNA helicase closely related to mRNA regulation, tumor proliferation and invasion. This article aimed to explore the effect of DDX6, a member of the DDX family, on the stability of CKMT1A mRNA, as well as the effect of the DDX6 CKMT1A axis on the proliferation and migration ability of human nasopharyngeal carcinoma cell CNE2 and its molecular mechanism. Methods: We retrieved the data of expressions of DDX6 and CKMT1A in human head and neck squamous cell carcinoma from The Cancer Genome Atlas (TCGA) database and performed a correlation analysis. Western blot was performed to detect the expressions of CKMT1A and DDX6 in human nasopharyngeal carcinoma tissues and normal nasopharyngeal tissues preserved by Affiliated Hospital of Nantong University. This study was approved by the Ethics Committee of Affiliated Hospital of Nantong University (Number: 2022-L114). We used transwell assay to detect cell migration ability, EdU assay to detect cell proliferation ability, and colony formation assay to detect clone formation ability. We transfect with lentivirus and plasmids to construct sh-DDX6, sh-CKMT1A, sh-CKMT1A+sh-DDX6 and oe-CKMT1A cell models derived from the human nasopharyngeal carcinoma cell line CNE2, preserved by Affiliated Hospital of Nantong University, to clarify the impact of DDX6 and CKMT1A expression levels on the malignant biological phenotypes of nasopharyngeal carcinoma cells. BALB/c nude mice subcutaneous xenograft tumor model was constructed to detect the effects of DDX6 and CKMT1A on nasopharyngeal carcinoma cells in mice. RNA stability assay was used to detect the effect of DDX6 knockout on CKMT1A mRNA and further clarify the molecular mechanism of DDX6. Results: DDX6 was highly expressed, CKMT1A level was low in human nasopharyngeal carcinoma tissue, and DDX6 was negatively correlated with CKMT1A expression. DDX6 inhibited protein translation of CKMT1A by disrupting its mRNA stability. Low expression of CKMT1A in CNE2 cells enhanced cell migration and proliferation ability, while high expression inhibited migration and proliferation ability. Knocking out DDX6 reversed the progression of malignant behavior caused by downregulation of CKMT1A. Low expression of CKMT1A promoted tumor cell growth in BALB/cnude mice subcutaneous xenograft tumor model, while low expression of DDX6 inhibited tumor cell growth. Knocking out DDX6 and CKMT1A simultaneously restored the inhibitory effect caused by knocking down DDX6 alone. Conclusion: DDX6 in nasopharyngeal carcinoma cells disrupts the stability of CKMT1A mRNA, negatively regulates CKMT1A protein translation, upregulates the proliferation and migration ability of nasopharyngeal carcinoma cells, and promotes malignant progression of nasopharyngeal carcinoma.

Key words: Nasopharyngeal carcinoma, CKMT1A, DDX6, Cell proliferation, Cell migration