CircMAN1A2 promotes vasculogenic mimicry of nasopharyngeal carcinoma cells through upregulating ERBB2 via sponging miR-940

Nasopharyngeal carcinoma (NPC) is the most prevalent human primary malignancy of the head and neck, and the presence of vasculogenic mimicry (VM) renders anti-angiogenic therapy ineffective and poorly prognostic. However, the underlying mechanisms are unclear. In the present study, we used miR-940 silencing and overexpression for in vitro NPC cell EdU staining, wound healing assay and 3D cell culture assay, and in vivo xenograft mouse model and VM formation to assess miR-940 function. We found that ectopic miR-940 expression reduced NPC cell proliferation, migration and VM, as well as tumorigenesis in vivo. By bioinformatic analysis, circMAN1A2 was identified as a circRNA that binds to miR-940. Mechanistically, we confirmed that circMAN1A2 acts as a sponge for miR-940, impairs the inhibitory effect of miR-940 on target ERBB2, and then activates the PI3K/AKT/mTOR signaling pathway using RNA-FISH, dual luciferase reporter gene and rescue analysis assays. In addition, upregulation of ERBB2 expression is associated with clinical staging and poor prognosis of NPC. Taken together, the present findings suggest that circMAN1A2 promotes VM formation and progression of NPC through miR-940/ERBB2 axis and further activates the PI3K/AKT/mTOR pathway. Therefore, circMAN1A2 may become a biomarker and therapeutic target for anti-angiogenic therapy in patients with nasopharyngeal carcinoma.