Long non-coding RNA GAS5 antagonizes the chemoresistance of pancreatic cancer cells through down-regulation of miR-181c-5p.

To explore the core mechanism of long non-coding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) in the regulation of multidrug resistance of pancreatic cancer cells. mRNA levels of GAS5, miR-181c-5p and Hippo pathway related genes were detected by quantitative real-time PCR (qRT-PCR). Protein levels of MDR-1, MST1, YAP and TAZ were measured by western blot. Cell viability was detected by MTT assay. The combination between GAS5 and miR-181c-5p was confirmed by RNA pull-down and RNA immunoprecipitation (RIP) assay. We also established pancreatic cancer-bearing mice model and analyzed tumor volumes. Our data showed GAS5 expression was significantly down-regulated, miR-181c-5p expression was significantly up-regulated in pancreatic cancer cells. Besides, Overexpresson of GAS5 obviously inhibited cell viability, while GAS5 knockdown showed the opposite outcome. Additionally, we also found that GAS5 negatively regulated miR-181c-5p, and miR-181c-5p dramatically promoted pancreatic cancer cell chemoresistance through inactivating the Hippo signaling. GAS5 regulated chemoresistance and Hippo pathway of pancreatic cancer cells via miR-181c-5p/Hippo. Finally, we confirmed that overexpression of GAS5 inhibited tumor growth in pancreatic cancer-bearing mice model. GAS5 regualtes Hippo signaling pathway via miR-181c-5p to antagonize the development of multidrug resistance in pancreatic cancer cells.

Gao ZQ ，Wang JF ，Chen DH ，Ma XS ，Yang W ，Zhe T ，Dang XW ... -  《-》

Upregulation of miR-181c contributes to chemoresistance in pancreatic cancer by inactivating the Hippo signaling pathway.

Chen M ，Wang M ，Xu S ，Guo X ，Jiang J ... -  《Oncotarget》

lncRNA GAS5-promoted apoptosis in triple-negative breast cancer by targeting miR-378a-5p/SUFU signaling.

Long-chain noncoding RNAs (lncRNAs) are involved in regulating the sensitivity of cancer cells to chemotherapeutic drugs, but the specific mechanism of action is not well understood. The aim of this study was to investigate the effect of lncRNA growth-stasis specific transcript 5 (GAS5) on triple-negative breast cancer (TNBC). Quantitative real-time polymerase chain reaction and flow cytometry were used to screen lncRNA associated with tumor resistance. Double luciferase reporter gene assay, flow cytometry, and Western blot assay were used to determine whether miRNA 378a-5p and SUFU were involved in tumor cell apoptosis induced by lncRNA GAS5. A mouse model of subcutaneous xenografts was established to investigate the relationship between lncRNA GAS5 and tumor resistance in vivo. In this study, the expression of lncRNA GAS5 was significantly downregulated in cells treated with paclitaxel (PTX) or cisplatin (CIS). Furthermore, TNBC cells with low expression of lncRNA GAS5 had a lower percentage of apoptosis under stress conditions, especially in serum-free medium. More interestingly, the expression level of lncRNA GAS5 in TNBC patients was associated with tumor resistance to PTX and CIS. In addition, RNA immunoprecipitation experiments confirmed that lncRNA GAS5 and miR-378 could directly bind to each other. Moreover, the miR-378a-5p target of SUFU could promote lncRNA GAS5-induced apoptosis of TNBC cells. Finally, lncRNA GAS5 overexpressed MDA-231R could enhance the sensitivity of TNBC to PTX. The above results confirmed that lncRNA GAS5 could induce apoptosis in TNBC cells by targeting miR-378a-5p/SUFU signaling.

Zheng S ，Li M ，Miao K ，Xu H ... -  《-》

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 ... -  《-》

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 ... -  《-》