GAS5 suppresses malignancy of human glioma stem cells via a miR-196a-5p/FOXO1 feedback loop.

Glioma stem cells (GSCs) make up highly tumorigenic subpopulations within gliomas, and aberrant expression of GSC genes is a major underlying cause of glioma pathogenesis and treatment failure. The present study characterized the expression and function of long non-coding RNA growth arrest specific 5 (GAS5) in GSCs in order to elucidate the molecular mechanisms by which GAS5 contributes to glioma pathogenesis. We demonstrate that GAS5 suppresses GSC malignancy by binding to miR-196a-5p. miR-196a-5p, an onco-miRNA, stimulates GSC proliferation, migration, and invasion, in addition to reducing levels of apoptosis. miR-196a-5p specifically downregulates the expression of forkhead box protein O1 (FOXO1) by targeting its 3' untranslated region (3'-UTR). FOXO1 upregulates expression of phosphotyrosine interaction domain containing 1 (PID1), thereby inhibiting GSC tumorigenicity and growth. FOXO1 also upregulates migration and invasion inhibitory protein (MIIP), resulting in attenuation of migration and invasion activities. Interestingly, we also show that FOXO1 promotes GAS5 transcription, thus forminga positive feedback loop. These data provide insights into potential new pathways for GSC molecular therapy and suggest that GAS5 may be an efficacious target for glioma treatments.

Zhao X ，Liu Y ，Zheng J ，Liu X ，Chen J ，Liu L ，Wang P ，Xue Y ... -  《BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH》

Long noncoding RNA GAS5 suppresses triple negative breast cancer progression through inhibition of proliferation and invasion by competitively binding miR-196a-5p.

Triple-negative breast cancer (TNBC) is considered to be the most aggressive and lethal type of breast cancer. Many studies have suggested that the dysfunction of long noncoding RNAs (lncRNAs) is correlated with breast cancer metastasis and progression. Here, we show that levels of the lncRNA, growth arrest-specific transcript 5 (GAS5), are decreased in TNBC tissues, and this down-regulation of GAS5 is associated with an aggressive tumor phenotype in patients, affecting clinical stage, lymph node metastasis and overall survival. Using an ectopic overexpression system in TNBC cells, we found that up-regulation of GAS5 can significantly attenuate proliferation and enhance apoptosis in TNBC cells. Through bioinformatics analysis and verification with qRT-PCR and luciferase assay, we found that GAS5 can bind to miR-196a-5p and there is a negative relationship between GAS5 and miR-196a-5p expression among TNBC patient samples. Furthermore, we demonstrated that overexpression of GAS5 can partially undermine the tumor promotion effect induced by ectopic expression of miR-196a-5p, including invasion and downstream FOXO1/PI3K/AKT signal pathway activation. In our study, GAS5 functioned as a competing endogenous RNA (ceRNA) antagonizing tumor promotion of miR-196a-5p-expressing TNBC cells. These data suggest that GAS5 can suppress TNBC progression by competitively binding miR-196a-5p, therefore GAS5 may be a prognostic biomarker of TNBC.

Li S ，Zhou J ，Wang Z ，Wang P ，Gao X ，Wang Y ... -  《-》

LncRNA GAS5 suppresses the tumorigenesis of cervical cancer by downregulating miR-196a and miR-205.

Yang W ，Hong L ，Xu X ，Wang Q ，Huang J ，Jiang L ... -  《-》

Long noncoding RNA GAS5 regulates the proliferation, migration, and invasion of glioma cells by negatively regulating miR-18a-5p.

Long noncoding RNAs, transcribed from a recently discovered class of noncoding genes, may play a critical role in regulating cellular processes, such as cell proliferation and apoptosis, as well as in cancer progression and metastasis. We previously detected the induction of growth arrest-specific 5 (GAS5) during glioma cell death. However, the function and underlying mechanism of GAS5 in human gliomas remain to be elucidated. Cell proliferation was detected using CellTiter 96® AQueous Non-Radioactive Cell Proliferation Assay (MTS) and tumorigenicity assay in nude mice. Wound-healing assay and transwell assay were utilized to examine the effects of GAS5 expression on glioma cells migration and invasion. In situ hybridization (ISH) was performed to evaluate GAS5 and microRNA (miR)-18a-5p levels in tissue microarrays. The relationship between GAS5 and miR-18a-5p was evaluated by quantitative reverse-transcription polymerase chain reaction and RNA precipitation. In this study, we demonstrated that overexpression of GAS5 inhibits malignant phenotypes in glioma cells, including proliferation, migration, and invasion, whereas GAS5 knockdown enhances these phenotypes. We further observed Argonaute 2-dependent reciprocal repression between GAS5 and miR-18a-5p in glioma cells. Downregulation of GAS5 and upregulation of miR-18a-5p were observed in glioma tissue microarrays relative to normal brain tissue by ISH. By deletion analysis, we identified one miR-18a-5p-binding site within exon 2 of GAS5 that is partially responsible for the tumor-suppressor functions of GAS5. Taken together, our findings suggest that GAS5 is a tumor suppressor in human gliomas that acts in part by repressing miR-18a-5p.

Liu Q ，Yu W ，Zhu S ，Cheng K ，Xu H ，Lv Y ，Long X ，Ma L ，Huang J ，Sun S ，Wang K ... -  《-》

Gas5 Exerts Tumor-suppressive Functions in Human Glioma Cells by Targeting miR-222.

Zhao X ，Wang P ，Liu J ，Zheng J ，Liu Y ，Chen J ，Xue Y ... -  《-》