Expression of the Annexin A1 gene is associated with suppression of growth, invasion and metastasis of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has a highly increased incidence rate (20/100,000) in Southern regions of China, while being rare in the rest of the world. NPC is a malignant type of cancer due to its high occurrence rate of metastasis; however, biomarkers for effective diagnosis and treatment are yet to be identified. Annexin A1 is a glucocorticoid-regulated member of a large superfamily of calcium and phospholipid-binding proteins and has been shown to have important roles in tumor development and progression, and was demonstrated to be a prognostic biomarker for head and neck cancer types. A previous study by our group showed that Annexin A1 was decreased in NPC tissue as compared with normal adjacent tissue. To investigate whether Annexin A1 is a potential biomarker for NPC, the present study assessed the effect of the Annexin A1 on the biological behavior (i.e., invasion and metastasis) of the highly metastatic NPC cell line 5-8F and the non-metastatic NPC cell line 6-10B. The expression levels of Annexin Al in the above two cell lines were determined by western blot analysis. Next, the recombinant plasmid pEGFP-C1-Annexin Al and the small interfering (si) RNA plasmid pRNAT-U6.1-Annexin Al were used and stably transfected into 5-8F and 6-10B cells, respectively. These established recombinant cell lines were then used to study the up- and downregulation of Annexin Al, respectively. The correlation of Annexin Al expression levels with the biological behavior of NPC cell lines was analyzed using a cell proliferation assay, flow cytometry, soft agar colony formation assay, as well as Transwell invasion and migration assays. The results demonstrated that upregulation of Annexin Al suppressed the proliferation, invasion and migration of NPC cells, while downregulation of Annexin Al promoted the proliferation, invasion and migration of NPC cells. These findings suggested that Annexin Al may be a potential biomarker for the development and prognosis of NPC, and its dysregulation may have an important role in its underlying pathogenesis.