miR-5188 augments glioma growth, migration and invasion through an SP1-modulated FOXO1-PI3K/AKT-c-JUN-positive feedback circuit
JOURNAL OF CELLULAR AND MOLECULAR MEDICINE
Authors: Yi, Renhui; Yang, Shaochun; Lin, Xian; Zhong, Liangying; Liao, Yuanyuan; Hu, Zheng; Huang, Tengyue; Long, Hao; Lin, Jie; Wu, Zhiyong; Xie, Cheng; Ding, Shengfeng; Luo, Jie; Luo, Qisheng; Song, Ye
Abstract
The biological effect and molecular mechanism of miR-5188 have not been thoroughly investigated. The study aims at elucidating the role of miR-5188 in glioma progression. Human glioma cell lines and tissues were used for functional and expression analysis. Cellular and molecular techniques were performed to explore the functions and mechanisms of miR-5188 in glioma. In our investigation, we demonstrated that miR-5188 promoted cell proliferation, the G1/S transition of the cell cycle, migration and invasion in glioma and reduced the lifespan of glioma-bearing mice. miR-5188 directly targeted FOXO1 and activated PI3K/AKT-c-JUN signalling, which enhanced miR-5188 expression. Moreover, the c-JUN transcription factor functionally bound to the miR-5188 promoter region, forming the positive feedback loop. The feedback loop promoted glioma progression through activating the PI3K/AKT signalling, and this loop is augmented by the interaction between SP1 and c-JUN. Moreover, it was also found that the miR-5188/FOXO1 axis is facilitated by SP1-activated PI3K/AKT/c-JUN signalling. In glioma samples, miR-5188 expression was found to be an unfavourable factor and was positively associated with the mRNA levels of SP1 and c-JUN, whereas negatively associated with the mRNA levels of FOXO1. Our investigation demonstrates that miR-5188 could function as a tumour promoter by directly targeting FOXO1 and participating in SP1-mediated promotion of cell growth and tumorigenesis in glioma.
Phospholipase D1 is upregulated by vorinostat and confers resistance to vorinostat in glioblastoma
JOURNAL OF CELLULAR PHYSIOLOGY
Authors: Kang, Dong Woo; Hwang, Won Chan; Noh, Yu Na; Kang, Youra; Jang, Younghoon; Kim, Jung-Ae; Min, Do Sik
Abstract
Glioblastoma (GBM) is an aggressive brain tumor and drug resistance remains a major barrier for therapeutics. Epigenetic alterations are implicated in GBM pathogenesis, and epigenetic modulators including histone deacetylase (HDAC) inhibitors are exploited as promising anticancer therapies. Here, we demonstrate that phospholipase D1 (PLD1) is a transcriptional target of HDAC inhibitors and confers resistance to HDAC inhibitor in GBM. Treatment of vorinostat upregulates PLD1 through PKC zeta-Sp1 axis. Vorinostat induces dynamic changes in the chromatin structure and transcriptional machinery associated withPLD1promoter region. Cotreatment of vorinostat with PLD1 inhibitor further attenuates invasion, angiogenesis, colony-forming capacity, and self-renewal capacity, compared with those of either treatment. PLD1 inhibitor overcomes resistance to vorinostat in GBM cells intracranial GBM tumors. Our finding provides new insight into the role of PLD1 as a target of resistance to vorinostat, and PLD1 inhibitor might provide the basis for therapeutic combinations with improved efficacy of HDAC inhibitor.