Argonaute 2 and nasopharyngeal carcinoma: a genetic association study and functional analysis

Background Argonaute 2 (AGO2), a central component of RNA-induced silencing complex, plays critical roles in cancer. We examined whether the single nucleotide polymorphisms (SNPs) of AGO2 were related to the risk of nasopharyngeal carcinoma (NPC). Methods Twenty-five tag SNPs within AGO2 were genotyped in Guangxi population consisting of 855 NPC patients and 1036 controls. The SNPs significantly associated with NPC were further replicated in Guangdong population consisting of 996 NPC patients and 972 controls. Functional experiments were conducted to examine the biologic roles of AGO2 in NPC. Results A significantly increased risk of advanced lymph node metastasis of NPC was identified for the AGO2 rs3928672 GA + AA genotype compared with GG genotype in both the Guangxi and Guangdong populations (combined odd ratio = 2.08, 95 % confidence interval = 1.44-3.01, P = 8.60 × 10 −5 ). Moreover, the AGO2 protein expression levels of rs3928672 GA + AA genotype carriers were higher than the GG genotype carriers in the NPC tissues ( P = 0.041), and AGO2 was significantly over-expressed in NPC tissues compared with non-cancerous nasopharyngeal tissues ( P = 0.011). In addition, AGO2 knockdown reduced cell proliferation, induced apoptosis, and inhibited migration of NPC cells. Furthermore, gene expression microarray showed that genes altered following AGO2 knockdown were clustered in tumorigenesis and metastasis relevant pathways. Conclusions Our findings suggest that the genetic polymorphism in AGO2 may be a risk factor for the advanced lymph node metastasis of NPC in Chinese populations, and AGO2 acts as an oncogene in the development of NPC.