Long Non-Coding RNA MALAT1 Interacts With miR-204 to Modulate Human Hilar Cholangiocarcinoma Proliferation, Migration, and Invasion by Targeting CXCR4

Long Noncoding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) Promotes Renal Cell Carcinoma Progression via Sponging miRNA-429

Background

It is well known that long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is closely correlated with the tumorigenesis of multiple cancers, including renal cell carcinoma (RCC). However, the potential functional mechanism is still elusive.

Material/Methods

In our present research, quantitative real-time polymerase chain reaction (qRT-PCR) was performed for the measurement of MALAT1 and miR-429. CCK-8 assay and Transwell assay were performed for the proliferation, migration, and invasion abilities of RCC cells. Dual-luciferase reporter assay was performed to validate the interaction within MALAT1 and miR-429.

Results

Data found that MALAT1 was overexpressed in RCC clinical samples and cell lines. Moreover, loss-of-functional experiments showed that MALAT1 knockdown suppress the proliferation, migration, and invasion abilities of RCC cells. RT-PCR showed that miR-429 expression was downregulated in RCC cell lines, which was negatively correlated with that of MALAT1. Bioinformatics analysis suggested that miR-429 had complementary binding sequences with MALAT1, which was confirmed by dual-luciferase reporter assay.

Conclusions

In summary, our results concluded that MALAT1 functioned as an oncogene in RCC by sponging miR-429, acting as its competing endogenous RNA (ceRNA).

NcRNAs and Cholangiocarcinoma

Cholangiocarcinoma (CCA) is the most common primary biliary malignancy with poor prognosis. Less understanding of its etiology and pathogenesis makes the diagnosis and therapy difficult. Recently, accumulating evidences have demonstrated that deregulated expression of non-coding RNAs (ncRNAs) is closely associated with the etiopathogenesis of CCA. NcRNAs which lack open reading frame are a heterogeneous class of transcribed RNA molecules, including microRNAs, long non-coding RNAs and circular RNAs. Several studies have shown ncRNAs dysregulation is a common central event occurring in CCA and has the potential of being therapy targets. Moreover, ncRNAs can be easily detected in cancer tissues and biofluids, representing valuable tools for diagnosis. In this review, we illustrate the role of ncRNA in the CCA and discuss their potential clinical value.

LncRNAs regulate cancer metastasis via binding to functional proteins

Cancer is one of the leading causes of death worldwide, and metastasis is a crucial characteristic of malignancy. Recent studies have shown that lncRNAs play an important role in regulating cancer metastasis through various molecular mechanisms. We briefly summarize four known molecular functions of lncRNAs, including their role as a signal, decoy, guide and scaffold. No matter which pattern lncRNAs follow to carry out their functions, the proteins that lncRNAs bind to are important for them to exhibit their gene-regulating properties. We further illustrate that lncRNAs regulate the localization, stabilization or modification of their binding proteins to realize the binding role of lncRNAs. In this review, we focus on the interactions between lncRNAs and their binding proteins; moreover, we focus on the mechanisms of the collaborative work of lncRNAs and their binding proteins in cancer metastasis, thus evaluating the potential of lncRNAs as prospective novel therapeutic targets in cancer.

BANCR contributes to the growth and invasion of melanoma by functioning as a competing endogenous RNA to upregulate Notch2 expression by sponging miR‑204

BRAF-activated non-coding RNA (BANCR) is a long non-coding RNA (lncRNA) that contributes to the initiation and development of many solid tumors, including melanoma. However, the BANCR functions and downstream mechanisms are largely unknown. In this study, we aim to investigate how BANCR participates in the proliferation and migration of malignant melanoma and elucidate the underlying mechanism in this process. We found that the expression of the BANCR was low in melanocytic nevus and human melanocytes but high in melanoma tissues and cell lines. Knockdown of BANCR inhibited melanoma cell proliferation and invasion, and induced cell apoptosis. The decreased expression of relative marker proteins further demonstrated the inhibitory effect of BANCR siRNA in cell growth and migration. Then, we detected downregulation of microRNA-204 (miR‑204), a suppressor of melanoma growth, in melanoma tissues and cell lines. We identified that miR‑204 was a direct target of BANCR and neurogenic locus notch homolog protein 2 (Notch2) was a direct target of miR‑204. BANCR may promote melanoma cell growth through inhibition of miR‑204, leading to the activation of Notch2 pathway. By tumorigenicity assay in BALB/c nude mice, we further demonstrated that BANCR knockdown inhibited tumor growth in vivo. Our results suggest the BANCR/miR‑204/Notch2 axis mediates melanoma cell proliferation and tumor progression.

miRNA and lncRNA as biomarkers in cholangiocarcinoma(CCA)

The microRNAs are a group of 20 nucleotides-long non-coding RNAs. By binding to the 3'UTR region of target mRNA, microRNAs can perform extensive actions mediating gene expression at post-trancriptional stages. It makes microRNAs serve as very crucial regulators in various biological progress including carcinogenesis. Long non-coding RNAs, however, are a subgroup of RNA with the length of 200 nucleotides. Unlike microRNAs, long non-coding RNAs can form secondary of tertiary domain based on their length. With the ability of directly interacting with DNA, RNA, protein, long non-coding RNAs have promoting or inhibitive functions in gene expression regulation. Furthermore, the abnormal expression of certain long non-coding RNAs has roused people's interest in the role of long non-coding RNAs in tumorigenesis. Although the connection between microRNA/long non-coding RNA and CCA has been a hot field to researchers, the link between molecular mechanism and clinical outcome has been barely built. This review takes a retrospect at the latest researches on the link between microRNA/long non-coding RNA and cholangiocarcinoma and the potential of microRNA/long non-coding RNA serving as distinctive biomarkers for CCA in clinical practice.

MALAT1/miR-127-5p Regulates Osteopontin (OPN)-Mediated Proliferation of Human Chondrocytes Through PI3K/Akt Pathway

Osteoarthritis (OA) is characterized by progressive destruction of articular cartilage, resulting in significant disability. Chondrocytes present in various types of cartilage and are responsible for the growth and maintenance of the tissue. Over-proliferation of human chondrocytes may contributes to OA pathological process. Previously, we revealed that miR-127-5p could inhibit the proliferation of human chondrocytes through osteopontin (OPN). In the present study, we used online tools to figure out several candidates lncRNAs which were potentially correlated with miR-127-5p. Through assessing the expression levels of the candidates lncRNAs, metastasis associated lung adenocarcinoma transcript 1 (MALAT1) was chosen as a further research subject. MALAT1 knockdown significantly repressed human OA chondrocyte proliferation, as well as the protein levels of OPN, p-PI3K, and p-Akt in OA chondrocytes. As verified by luciferase assays, MALAT1 directly bound to miR-127-5p to inhibit miR-127-5p expression. Then we achieved miR-127-5p inhibition through miR-127-5p inhibitor transfection; the miR-127-5p inhibition could promote chondrocyte proliferation, as well as the protein levels of OPN, p-PI3K, and p-Akt; in addition, the MALAT1 knockdown partially reversed the promotive effect of miR-127-5p inhibition on chondrocyte proliferation, OPN and PI3K/Akt signaling-related protein levels. Taken together, MALAT1 could directly bind to miR-127-5p to inhibit its expression, so as to rescue OPN expression and promote chondrocyte proliferation through PI3K/Akt pathway. Targeting MALAT1 so as to rescue miR-127-5p expression in OA might help to inhibit chondrocyte proliferation through miR-127-5p-mediated OPN regulation and downstream PI3K/Akt pathway. J. Cell. Biochem. 119: 431-439, 2018. © 2017 Wiley Periodicals, Inc.

Knockdown of MALAT1 expression inhibits HUVEC proliferation by upregulation of miR-320a and downregulation of FOXM1 expression

Regulation of cancer angiogenesis could be a useful strategy in cancer therapy. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA), and can induce cancer cell proliferation, while lncRNAs, generally are able to act as microRNA (miRNA) sponges. The latter is a type of competitive endogenous RNA (ceRNA) that regulates expression of the targeting miRNAs and protein-coding genes. This study investigated the proliferative role of MALAT1 in human umbilical vein endothelial cells (HUVECs) and the underlying molecular events. The data showed that knockdown of MALAT1 expression using MALAT1 siRNA inhibited HUVEC proliferation and also significantly decreased levels of FOXM1 mRNA and protein in vitro, while knockdown of FOXM1 expression reduced HUVEC proliferation. Annotation of HUVEC microarray data revealed that seven miRNAs, including miR-320a, were upregulated after knockdown of MALAT1 expression in HUVECs. MALAT1 was shown to reciprocally interact with miR-320a, i.e., expression of one negatively regulated levels of the other, whereas knockdown of MALAT1 expression promoted miR-320a levels. Furthermore, miR-320a could directly target and inhibit FOXM1 expression in HUVECs. Knockdown of MALAT1 expression enhanced miR-320a expression but reduced FOXM1 expression resulting in downregulation of HUVEC proliferation. However, such an effect was inhibited by miR-320a depletion. In conclusion, this study demonstrates that miR-320a plays an important role in mediating the effects of MALAT1 on HUVEC proliferation by suppression of FOXM1 expression. Thus, targeting of this gene pathway could be a novel strategy in cancer therapy.