MiR-320 inhibits the growth of glioma cells through downregulating PBX3

Cuicui Pan, Hua Gao, Ni Zheng, Qi Gao, Yuanquan Si, Yueran Zhao

MiR-320 is downregulated in multiple cancers, including glioma and acts as tumor suppressor through inhibiting tumor cells proliferation and inducing apoptosis. PBX3 (Pre-B cell leukemia homeobox 3), a putative target gene of miR-320, has been reported to be upregulated in various tumors and promote tumor cell growth through regulating MAKP/ERK pathway. This study aimed to verify whether miR-320 influences glioma cells growth through regulating PBX3. Twenty-four human glioma and paired adjacent nontumorous tissues were collected for determination of miR-320 and PBX3 expression using RT-qPCR and western blot assays. Luciferase reporter assay was performed to verify the interaction between miR-320 and its targeting sequence in the 3' UTR of PBX3 in glioma cells U87 and U251. Increased miR-320 level in U87 and U251 cells was achieved through miR-320 mimic transfection and the effect of which on glioma cells growth, proliferation, cell cycle, apoptosis and activation of Raf-1/MAPK pathway was determined using MTT, colony formation, flow cytometry and western blot assays. PBX3 knockdown was performed using shPBX3 and the influence on MAPK pathway activation was evaluated. MiR-320 downregulation and PBX3 upregulation was found in glioma tissues. Luciferase reporter assays identified miR-320 directly blinds to the 3' UTR of PBX3 in glioma cells. MiR-320 mimic transfection suppressed glioma cells proliferation, and induced cell cycle arrest and apoptosis. Both miR-320 overexpression and PBX3 knockdown inhibited Raf-1/MAPK activation. MiR-320 may suppress glioma cells growth and induced apoptosis through the PBX3/Raf-1/MAPK axis, and miR-320 oligonucleotides may be a potential cancer therapeutic for glioma.