LncRNA DLG5-AS1 facilitates breast cancer cell proliferation and invasion by promoting EZH2-mediated transcriptional silencing of SFRP1

Rapid proliferation and metastasis of breast cancer contributed to poor clinical prognosis. Accumulating evidence revealed that the dysregulation of long noncoding RNAs (lncRNAs) was associated with breast cancer progression. However, the role of lncRNA DLG5-AS1 in breast cancer has not been established. Here, we investigated the mechanisms of DLG5-AS1 in the development of breast cancer. We found that the expression of DLG5-AS1 was significantly upregulated in breast cancer tissues and cell lines. DLG5-AS1 interference markedly restrained AU565 cell proliferation, invasion, the expression of apoptosis related (caspase3 and caspase8) and Wnt/β-catenin pathway related proteins (wnt5a, β-Catenin and c-Myc), as well as promoted cell apoptosis, whereas DLG5-AS1 overexpression showed an opposite effects. In addition, DLG5-AS1 could directly bind with miR-519 b-3p. We also found that enhancer of zeste homolog 2 (EZH2) is a direct target of miR-519 b-3p, and DLG5-AS1 upregulated EZH2 expression by inhibiting the expression of miR-519 b-3p. EZH2 restrained secreted frizzled related protein 1 (SFRP1) expression through inducing H3 histone methylation in its promoter. MiR-519 b-3p overexpression or SFRP1 knockdown memorably reversed the effects of DLG5-AS1 overexpression on cell functions and Wnt/β-Catenin pathway related protein expression. Finally, in vivo experiments demonstrated that silencing of DLG5-AS1 inhibited xenograft tumor development in mice. Taken together, these findings demonstrated that DLG5-AS1 facilitated cell proliferation and invasion by promoting EZH2-mediated transcriptional silencing of SFRP1 in breast cancer.

Long Non-Coding RNA Duxap8 Facilitates Cell Proliferation and Induces Apoptosis in Colorectal Cancer via miR-519b/ZNF277 Axis

Introduction

Long non-coding RNAs (LncRNAs) play a critical role in development and progression of various cancers. More and more researchers pay attention to the effect of lncRNA on regulating the cancer. However, the function and mechanism of Duxap8 in colorectal cancer have not been studied.

Methods

Reverse transcription quantitative PCR (RT-qPCR), cell counting kit-8 (CCK-8), 5-ethynyl-20-deoxyuridine (EdU), colony formation assay, flow cytometry, TdT-mediated dUTP nick-end labeling (TUNEL), Western blot, hematoxylin-eosin staining (HE), in situ hybridization (ISH) analysis, immunohistochemistry (IHC) and tumor transplantation experiment were performed to investigate the function and mechanism of Duxap8 in colorectal cancer.

Results

We found that the expression level of Duxap8 in colorectal cancer was closely correlated with tumor size (P = 0.024), tumor depth (P = 0.035) and lymphatic invasion (P =0.067) among 50 colorectal cancer patients. Then, we proved that the expression level of Duxap8 was significantly increased in human colorectal cancer tissues and cell lines. Functionally, Duxap8 knockdown inhibited the proliferation and induced the apoptosis of colorectal cancer cells, while Duxap8 overexpression facilitated the proliferation and suppressed the apoptosis in colorectal cancer in vitro. Moreover, knockdown of Duxap8 inhibited the size and weight of tumors in mice injected with colorectal cancer cells, overexpression of Duxap8 promoted the growth of colorectal cancer cells in vivo. Mechanically, we found that Duxap8 was principally located in the cytoplasm. Furthermore, Duxap8 functioned as a competing endogenous RNA to induce the development and progression of colorectal cancer through sponging miR-519b-3p to upregulate ZNF277.

Discussion

Taken together, our results demonstrated that Duxap8 enhanced the expression level of ZEB1 to promote via competing for miR-519b-3p, which might be a promising molecular therapeutic target of colorectal cancer.

LncRNA SNHG14 promotes cell proliferation and invasion in colorectal cancer through modulating miR-519b-3p/DDX5 axis

Numbers of studies suggest that long non-coding RNAs (lncRNAs) exert an important role in cancer progression. It is reported that lncRNA SNHG14 (SNHG14) promotes cell proliferation and invasion in many cancers. However, the underlying molecular mechanism of SNHG14 in colorectal cancer (CRC) remains unclear. In our study, we found that SNHG14 is highly expressed in CRC tissues and cells, especially in SW480 and HT-29 cells. In addition, sh-SNHG14 inhibits cell proliferation, cell migration and invasion, promotes cell apoptosis in CRC cell lines. Furthermore, we found that SNHG14 functions as a sponge for miR-519b-3p, while the DEAD box protein 5 (DDX5) is a downstream target gene of miR-519b-3p, and the functions of miR-519b-3p inhibitors on the CRC progression could be rescued by downregulation of DDX5. Our findings suggest that SNHG14 promotes the CRC progression by miR-519b-3p/DDX5 axis, implying the promising therapeutic target of SNHG4 for CRC patients.

LINC01419 promotes cell proliferation and metastasis in lung adenocarcinoma via sponging miR-519b-3p to up-regulate RCCD1

Lung adenocarcinoma (LUAD) is one of the most common type of lung cancer notorious for the high incidence and mortality around the world. Long non-coding RNAs (LncRNAs) are defined as a class of RNAs with length more than 200 nucleotides. Mounting studies have proved that lncRNAs are related closely to incidence of diseases and play crucial roles in cancer progression. Although LINC01419 has been studied in several cancers, the function and mechanism of LINC01419 in LUAD remains a mystery. Our findings showed that LINC01419 level was high in LUAD cells, and LINC01419 knockdown inhibited carcinogenesis via suppressing cell proliferation, migration as well as invasion. Moreover, bioinformatics prediction, luciferase reporter experiments and RIP assay were used to confirm miR-519-3p was sequestered and negatively regulated by LINC01419. Subsequently, RCCD1 was identified as a miR-519b-3p target and had inverse relationship with miR-519b-3p. LINC01419 was positively related to RCCD1. Furthermore, rescue assays confirmed that miR-519b-3p inhibitor or RCCD1 overexpression could neutralize the effect of LINC01419 silenced in cell proliferation, migration and invasion. Taken together, all the results indicated that LINC01419 exhibited oncogenic behaviors LUAD via binding to miR-519b-3p to enhance the expression of RCCD1, manifesting the underlying therapy values of LINC01419 in LUAD.