MicroRNA-32-5p inhibits metastasis by directly targeting VPS4B and increases sensitivity to dihydroartemisinin in neuroblastoma

Abstract Background Neuroblastoma (NB) is a malignant pediatric tumor requiring new therapies. Accumulating evidence has confirmed that microRNAs play critical roles in NB metastasis. Dihydroartemisinin (DHA) is capable of inhibiting the growth of NB cells. The primary objective of the current investigation was to characterize a newly discovered microRNA, miR-32-5p, in terms of the functional role, underlying mechanism of action, and potential synergistic therapeutic impact in the context of NB metastasis. Materials and methods Real-time quantitative polymerase chain reaction and Western blotting were employed to assess the expression levels of miR-32-5p and its target, vacuolar protein sorting 4B (VPS4B). Furthermore, Transwell assay was utilized to evaluate in vitro cell migration and invasion, whereas a metastasis xenograft model was established in nude mice via caudal vein injections. Results Gene Expression Omnibus database and real-time quantitative polymerase chain reaction analysis showed that miR-32-5p was downregulated in human NB samples and NB cell lines, in comparison with the normal tissue and cell lines. Inhibiting miR-32-5p induced the migration and invasion of NB cells, whereas overexpression of miR-32-5p prevented the migration and invasion in NB cell lines. Furthermore, VPS4B was identified as the direct target of miR-32-5p and the miR-32-5p reduction associated with NB metastasis upregulated the expression of VPS4B. Conversely, overexpression of VPS4B reversed the suppressive effects of miR-32-5p on NB cells. Moreover, miR-32-5p increased the sensitivity to DHA both in NB cells and in the metastasis xenograft model of nude mice. Conclusions The downregulation of miR-32-5p in NB regulates NB metastasis by targeting VPS4B. Moreover, miR-32-5b can improve the sensitivity of DHA in the xenograft mouse model. Our findings have important implications for the combined application of miR-32-5p and DHA in the treatment of NB.