BackgroundProtein coding genes account for only about 2% of the human genome, whereas the vast majority of transcripts are non-coding RNAs including long non-coding RNAs. A growing volume of literature has proposed that lncRNAs are important players in cancer. HOTAIR was previously shown to be an oncogene and negative prognostic factor in a variety of cancers. However, the factors that contribute to its upregulation and the interaction between HOTAIR and miRNAs are largely unknown.MethodsA computational screen of HOTAIR promoter was conducted to search for transcription-factor-binding sites. HOTAIR promoter activities were examined by luciferase reporter assay. The function of the c-Myc binding site in the HOTAIR promoter region was tested by a promoter assay with nucleotide substitutions in the putative E-box. The association of c-Myc with the HOTAIR promoter in vivo was confirmed by chromatin immunoprecipitation assay and Electrophoretic mobility shift assay. A search for miRNAs with complementary base paring with HOTAIR was performed utilizing online software program. Gain and loss of function approaches were employed to investigate the expression changes of HOTAIR or miRNA-130a. The expression levels of HOTAIR, c-Myc and miRNA-130a were examined in 65 matched pairs of gallbladder cancer tissues. The effects of HOTAIR and miRNA-130a on gallbladder cancer cell invasion and proliferation was tested using in vitro cell invasion and flow cytometric assays.ResultsWe demonstrate that HOTAIR is a direct target of c-Myc through interaction with putative c-Myc target response element (RE) in the upstream region of HOTAIR in gallbladder cancer cells. A positive correlation between c-Myc and HOTAIR mRNA levels was observed in gallbladder cancer tissues. We predicted that HOTAIR harbors a miRNA-130a binding site. Our data showed that this binding site is vital for the regulation of miRNA-130a by HOTAIR. Moreover, a negative correlation between HOTAIR and miRNA-130a was observed in gallbladder cancer tissues. Finally, we demonstrate that the oncogenic activity of HOTAIR is in part through its negative regulation of miRNA-130a.ConclusionTogether, these results suggest that HOTAIR is a c-Myc-activated driver of malignancy, which acts in part through repression of miRNA-130a.

Background Gallbladder cancer is the most common biliary tract malignancy and not sensitive to chemotherapy. Autophagy is an important factor prolonging the survival of cancer cells under chemotherapeutic stress. We aimed to investigate the role of long non-coding RNAs (lncRNAs) in autophagy and chemoresistance of gallbladder cancer cells. Methods We established doxorubicin (Dox)-resistant gallbladder cancer cells and used microarray analysis to compare the expression profiles of lncRNAs in Dox-resistant gallbladder cancer cells and their parental cells. Knockdown or exogenous expression of lncRNA combined with in vitro and in vivo assays were performed to prove the functional significance of lncRNA. The effects of lncRNA on autophagy were assessed by stubRFP-sensGFP-LC3 and western blot. We used RNA pull-down and mass spectrometry analysis to identify the target proteins of lncRNA. Results The drug-resistant property of gallbladder cancer cells is related to their enhanced autophagic activity. And we found a lncRNA ENST00000425894 termed gallbladder cancer drug resistance-associated lncRNA1 (GBCDRlnc1) that serves as a critical regulator in gallbladder cancer chemoresistance. Furthermore, we discovered that GBCDRlnc1 is upregulated in gallbladder cancer tissues. Knockdown of GBCDRlnc1, via inhibiting autophagy at initial stage, enhanced the sensitivity of Dox-resistant gallbladder cancer cells to Dox in vitro and in vivo. Mechanically, we identified that GBCDRlnc1 interacts with phosphoglycerate kinase 1 and inhibits its ubiquitination in Dox-resistant gallbladder cancer cells, which leads to the down-regulation of autophagy initiator ATG5-ATG12 conjugate. Conclusions Our findings established that the chemoresistant driver GBCDRlnc1 might be a candidate therapeutic target for the treatment of advanced gallbladder cancer. Electronic supplementary material The online version of this article (10.1186/s12943-019-1016-0) contains supplementary material, which is available to authorized users.

Background Circular RNAs (circRNAs) have recently been identified as potential functional modulators of the cellular physiology processes. The study aims to uncover the potential clinical value and driving molecular mechanisms of circRNAs in gallbladder cancer (GBC). Patients and methods We performed RNA sequencing from four GBC and paired adjacent normal tissues to analyze the circRNA candidates. Quantitative real-time polymerase chain reaction (QRT-PCR) was used to measure the circFOXP1 expression from 40 patient tissue samples. Short hairpin RNA mediated knockdown or exogenous expression of circFOXP1 combined with in vitro and in vivo assays were performed to prove the functional significance of circFOXP1. Double luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays were also performed. Results By performing RNA sequencing from GBC and paired adjacent normal tissues to analyze the circRNA candidates, we identified that circFOXP1 (hsa_circ_0008234) expression was significantly upregulated in GBC tissues and positively associated with lymph node metastasis, advanced TNM stage and poor prognosis in patients. Short hairpin RNA mediated knockdown or exogenous expression of circFOXP1 combined with in vitro assays demonstrated that circFOXP1 has pleiotropic effects, including promotion of cell proliferation, migration, invasion, and inhibition of cell apoptosis in GBC. In vivo, circFOXP1 promoted tumor growth. Mechanistically, double luciferase reporter, RNA immunoprecipitation (RIP) and biotin-labeled RNA pull-down assays clarified that circFOXP1 interacted with PTBP1 that could bind to the 3’UTR region and coding region (CDS) of enzyme pyruvate kinase, liver and RBC (PKLR) mRNA (UCUU binding bites) to protect PKLR mRNA from decay. Additionally, circFOXP1 acted as the sponge of miR-370 to regulate PKLR, resulting in promoting Warburg effect in GBC progression. Conclusions These results demonstrated that circFOXP1 serve as a prognostic biomarker and critical regulator in GBC progression and Warburg effect, suggesting a potential target for GBC treatment.