Growing evidence has demonstrated that in tumor progression, circular RNAs (circRNAs) play important roles. However, the roles of circRNAs in nasopharyngeal carcinoma (NPC) have not been fully elucidated. In this study, it was demonstrated that that hsa_circ_0033074 (circSERPINA3) expression was found to be significantly upregulated in NPC tissues and cell lines. CircSERPINA3 inhibition significantly attenuated the invasion and proliferation abilities of NPC cells. The mechanism by which circSERPINA3 interacted with miR-944 was identified and MDM2 was demonstrated to function as a target gene of miR-944. Rescue experiments showed that miR-944 inhibitors or MDM2 overexpression reserved the effects of circSERPINA3 knockdown on NPC progression. Therefore, our study uncovered the circSERPINA3/miR-944/MDM2 axis in NPC, which may be a potential NPC therapeutic target.

Circular RNAs (circRNAs) are implicated in the initiation and progress of several diseases, including cancer. However, the precise role of circRNAs in human nasopharyngeal carcinoma (NPC) remains unclear. In this research, we found a new circRNA hsa_circ_0001554 (circRANBP17), which was derived from the RAN binding protein 17 (RANBP17). Our qRT-PCR data found that circRANBP17 expression was up-regulated in NPC tissue and cells. Functional silencing studies revealed that circRANBP17 inhibited NPC cell proliferation and invasion in vitro, and circRANBP17 down-regulation also reduced tumor growth in nude mice. MiR-635 was demonstrated as a direct target of circRANBP17; circRANBP17 up-regulated RUNX2 expression levels by sponging miR-635, thereby promoting NPC proliferation and invasion. Thus, our data provide the evidence for the first time that circRANBP17 is a new onco-circRNA via miR-635/RUNX2 axis regulation, and may function as a novel therapeutic target for NPC treatment.