Long non‑coding RNA DANCR aggravates breast cancer through the miR‑34c/E2F1 feedback loop

Emerging scientific evidence has suggested that the long non‑coding (lnc)RNA differentiation antagonizing non‑protein coding RNA (DANCR) serves a significant role in human tumorigenesis and cancer progression; however, the precise mechanism of its function in breast cancer remains to be fully understood. Therefore, the objective of the present study was to manipulate DANCR expression in MCF7 and MDA‑MB‑231 cells using lentiviral vectors to knock down or overexpress DANCR. This manipulation, alongside the analysis of bioinformatics data, was performed to investigate the potential mechanism underlying the role of DANCR in cancer. The mRNA and/or protein expression levels of DANCR, miR‑34c‑5p and E2F transcription factor 1 (E2F1) were assessed using reverse transcription‑quantitative PCR and western blotting, respectively. The interactions between these molecules were validated using chromatin immunoprecipitation and dual‑luciferase reporter assays. Additionally, fluorescence in situ hybridization was used to confirm the subcellular localization of DANCR. Cell proliferation, migration and invasion were determined using 5‑ethynyl‑2'‑deoxyuridine, wound healing and Transwell assays, respectively. The results of the present study demonstrated that DANCR had a regulatory role as a competing endogenous RNA and upregulated the expression of E2F1 by sequestering miR‑34c‑5p in breast cancer cells. Furthermore, E2F1 promoted DANCR transcription by binding to its promoter in breast cancer cells. Notably, the DANCR/miR‑34c‑5p/E2F1 feedback loop enhanced cell proliferation, migration and invasion in breast cancer cells. Thus, these findings suggested that targeting DANCR may potentially provide a promising future therapeutic strategy for breast cancer treatment.

Expression of SOX2OT, DANCR and TINCR long non‑coding RNAs in papillary thyroid cancer and its effects on clinicopathological features

Long non‑coding RNAs (lncRNAs) are molecules that are >200 base pairs long and do not encode a protein. However, they perform important roles in regulating gene expression. Recent studies have revealed that the changes in the expressions of lncRNAs serve a role in the development and metastases of a number of types of cancer. A number of studies have been published on the association of SOX2 overlapping transcript (SOX2OT), differentiation antagonizing non‑protein coding RNA (DANCR) and tissue differentiation‑induced non‑coding RNA (TINCR) expression with various types of cancer. However, researchers have not yet studied their roles in papillary thyroid cancer or at least, those roles are not clarified. The aim of the present study was to investigate the expression and clinical significance of SOX2OT, DANCR and TINCR in papillary thyroid cancer (PTC). A total of 102 patients with PTC were included in the present study. Reverse transcription‑quantitative PCR method was used to determine the relative gene expression levels of lncRNAs and then the relationship between expressions of lncRNAs and clinical characteristics of the subjects was analyzed in detail. Expression levels of SOX2OT (P=0.016) and DANCR (P=0.017) increased in the tumor samples in contrast to the normal tissues. No significant difference was observed in the expression level of TINCR (P=0.298). In addition, SOX2OT expression was associated with micro carcinoma (P<0.001), tumor size (P=0.010) and primary tumor (P=0.006), while DANCR expression was associated with age (P=0.030) and micro carcinoma (P=0.004). The findings of the present study indicated that DANCR may contribute to the development of PTC while SOX2OT may contribute to both the development and progression of PTC.

Long non‑coding RNA DANCR represses the viability, migration and invasion of multiple myeloma cells by sponging miR‑135b‑5p to target KLF9

Multiple myeloma (MM) is a malignancy of plasma cells that leads to marrow failure and bone lesions. Numerous studies have verified the link between long non‑coding RNAs (lncRNAs) and MM. The present study aimed to examine the role and underlying mechanism of differentiation antagonizing non‑protein coding RNA (DANCR) in MM cells. The relative expression levels of DANCR, microRNA (miR)‑135b‑5p and Krüppel‑like factor 9 (KLF9) were examined using reverse transcription‑quantitative PCR. Cell viability was assessed using the MTT assay, while relative cell migration and invasion were evaluated using Transwell assays. Moreover, the dual‑luciferase reporter assay was used to examine the interplay between DANCR, miR‑135b‑5p and KLF9. Western blotting was performed to determine the expression level of KLF9. It was found that lncRNA DANCR and KLF9 were downregulated, while miR‑135b‑5p was upregulated in the serum of patients with MM and in MM cells compared with the controls. Overexpressing DANCR or knocking down miR‑135b‑5p reduced the viability of the MM cells, as well as restrained MM cells from migrating and invading. Furthermore, DANCR directly targeted miR‑135b‑5p and was negatively correlated with miR‑135b‑5p. It was also found that KLF9 was targeted by miR‑135b‑5p and was inversely correlated with miR‑135b‑5p expression. The impact of lncRNA DANCR‑mediated suppression on cell viability, invasion and migration was partially abolished by short hairpin RNA KLF9 or miR‑135b‑5p mimics transfection in MM cells. Thus, it was suggested that lncRNA DANCR repressed the viability, migration and invasion of MM cells by sponging miR‑135b‑5p to target KLF9.