Long non-coding RNA HOTAIR, a c-Myc activated driver of malignancy, negatively regulates miRNA-130a in gallbladder cancer

Abstract

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.

HOTAIR, a long non-coding RNA driver of malignancy whose expression is activated by FOXC1, negatively regulates miRNA-1 in hepatocellular carcinoma

“…It has been recently reported that HOTAIR is a c-Myc-activated driver of malignancy, which acts in part through repressing miR-130a (44). The current study demonstrated that LV3-HOTAIR effectively promotes HepG2 cell formation of clones, as well as growth of animal tumor xenografts.…”

Noncoding RNAs in Gallbladder Cancer

“…Moreover, the levels of lncRNA HOTAIR were signiicantly higher in 65 GBC tissues, especially in those in higher pathological stage, in a recent report [13]. At a molecular level, HOTAIR expression was shown to be regulated by c-Myc [13].…”

“…Also, miRNA-130a was found to be signiicantly downregulated in cancer tissues, compared with adjacent normal tissues; furthermore, its levels were negatively correlated to a lncRNA, HOX transcript antisense RNA (HOTAIR), which has been shown to be correlated with the metastatic progression of several carcinomas, and as a consequence, to be a negative prognostic factor [13]. We will return in this interaction later in this chapter, talking about lncRNAs in gallbladder cancer.…”

“…At a molecular level, HOTAIR expression was shown to be regulated by c-Myc [13]. As we mentioned before, regulators of HOTAIR activity include miRNA-130a, a tumor suppressor miRNA, and this relects the complexity of the regulatory networks in gallbladder cancer, which include several types…”

The role of microRNAs in gallbladder cancer

“…In addition, miR-130a levels were negatively associated with a lncRNA, HOX transcript antisense RNA (HOTAIR), which has been shown to be a poor prognostic factor in several carcinomas, and to be correlated with tumor metastases. Furthermore, loss of HOTAIR has been associated with the inhibition of cancer invasiveness (86). It was previously demonstrated that the expression of HOTAIR was negatively associated with miR-130a in GBC tissues, and that knockdown of HOTAIR may decrease the invasion of GBC cells, a phenotype that may be partially reversed by miR-130a inhibition.…”