1. Center of Image Diagnoses, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang 471003, China.
2. Henan Key Laboratory of Cancer Epigenetics; Cancer Institute, The First Affiliated Hospital, and College of Clinical Medicine of Henan University of Science and Technology, Luoyang 471003, China.
3. Medical College, Henan University of Science and Technology, Luoyang 471003, Henan, China.
Background: Circular RNAs (circRNAs) represent a class of broad and diversified endogenous RNAs that regulate gene expressions in eukaryotes. Hsa_circ_006675 has been proven as an important circRNA molecule in nasopharyngeal carcinoma (NPC), however, its function still remains elusive. This study aims to discuss the biofunctions of hsa_circ_0066755 in NPC.
Methods: We detected the expression levels of hsa_circ_0066755 in NPC patients by quantitative real-time polymerase chain reaction (qRT-PCR), and the corresponding ROC curves were plotted. Functional experiments including CCK-8, colony formation, Transwell assay and Xenograft experiment were conducted. Bioinformatics analysis was performed to seek miRNAs which might have binding sites with hsa_circ_0066755. Luciferase reporter assays were finally carried out to verify the binding sites.
Results: We found significant increases of hsa_circ_0066755 in the plasma and tissues of the patients. Moreover, its levels were positively correlated with clinical staging (P=0.019). The receiver operating characteristic (ROC) analysis showed that the area under the curves (AUCs) of tissue and plasma hsa_circ_0066755 for distinguishing NPC from non-cancerous controls were 0.8537 and 0.9044, respectively. Both tissue and plasma hsa_circ_0066755 testing presented a comparable diagnostic accuracy to the magnetic resonance imaging (MRI). Our in-vitro experiment showed that the overexpression of hsa_circ_0066755 facilitated the growth, proliferation, clone formation, invasion and migration of CNE-1 NPC cells, while its down-regulation showed completely opposite effects. The xenograft experiment showed that exogenous hsa_circ_0066755 could significantly enhance the in-vivo tumorigenic ability of CNE-1 cells. Rescue assay further confirmed hsa_circ_0066755 as a tumor facilitator by sponging miR-651.
Conclusions: Collectively, this study reported for the first time that hsa_circ_0066755 played a role of oncogene in NPC and could be used as an effective diagnostic marker for NPC, and that hsa_circ_0066755 / miR-651 axis also involved in the progression of NPC.
Keywords: circular RNA, hsa_circ_0066755, nasopharyngeal carcinoma, CNE-1, miR-651, sponge