Abstract
Malignant glioma is an often fatal type of cancer. Aberrant activation of STAT3 leads to glioma tumorigenesis. STAT3-induced transcription of protein-coding genes has been extensively studied; however, little is known about STAT3-regulated miRNA gene transcription in glioma tumorigenesis. In this study, we found that abnormal activation or decreased expression of STAT3 promotes or inhibits the expression of miR-182-5p, respectively. Bioinformatics analyses determined that tumor suppressor protocadherin-8 (PCDH8) is a candidate target gene of miR-182-5p. miR-182-5p negatively regulated PCDH8 expression by directly targeting its 3'-untranslated region. PCDH8 knockdown induced the proliferative and invasive capacities of glioma cells. Silencing of PCDH8 or miR-182-5p mimics could reverse the inhibitory effect of WP1066, a STAT3 inhibitor, or STAT3 knockdown in vitro and in vivo on glioma progression. Clinically, expression levels of PCDH8 were inversely correlated with those of p-STAT3 or miR-182-5p in glioblastoma tissues. These findings reveal that the STAT3/miR-182-5p/PCDH8 axis has a critical role in glioma tumorigenesis and that targeting the axis may provide a new therapeutic approach for human glioma. Cancer Res; 76(14); 4293-304. ©2016 AACR.