Hiding in Plain Sight: Rediscovering the Importance of Noncoding RNA in Human Malignancy

LINC00664/miR-411-5p/KLF9 feedback loop contributes to the human oral squamous cell carcinoma progression

OBJECTIVES

Oral squamous cell carcinoma (OSCC) is one of the most aggressive head and neck cancers with high incidence. Multiple studies have revealed that long non-coding RNAs (lncRNAs) play pivotal roles in tumorigenesis. However, the role of long intergenic non-protein coding RNA 664 (LINC00664) on the progression of OSCC was still unclear.

SUBJECTS AND METHODS

In this study, the expression of LINC00664 in OSCC tissues and cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The functional role of LINC0664 was estimated by cell counting kit-8 (CCK-8), transwell assays, Western blot in vitro, and xenograft tumor model in vivo. The regulatory mechanism was investigated by RNA-binding protein immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), and luciferase reporter assays.

RESULTS

LINC00664 was found to be upregulated in OSCC tissues and cell lines and was associated with poor prognosis of OSCC patients. LINC00664 knockdown suppressed OSCC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT). Moreover, Kruppel like factor 9 (KLF9) enhanced LINC00664 expression at transcription level. Interestingly, LINC00664 upregulated KLF9 expression by sponging miR-411-5p. In addition, knockdown of LINC00664 restrained tumor growth of OSCC in vivo.

CONCLUSION

Our study identified the oncogenic roles of LINC00664 in OSCC tumorigenesis and EMT via KLF9/LINC00664/miR-411-5p/KLF9 feedback loop, which provides new perspectives of the potential therapeutic target for OSCC.

Suppression of SIN3A by miR-183 Promotes Breast Cancer Metastasis

Recent work has established that SWI-independent-3 (SIN3) chromatin modification complexes play key roles in cancer progression. We previously demonstrated that knockdown of SIN3A expression promotes human breast cancer cell invasion and metastasis; however, the levels of SIN3A in patient breast carcinoma are not known. We therefore examined SIN3A mRNA and protein in patient tissues and determined that SIN3A expression is lower in breast carcinoma relative to normal breast. Given the 3'-untranslated region (UTR) of SIN3A has several conserved binding sites for oncogenic miRNA, we hypothesized that SIN3A is targeted by miRNA and found that ectopic miR-183 results in decreased SIN3A in breast carcinoma cell lines. Functionally, we demonstrate that miR-183 promotes breast cancer cell migration and invasion in a SIN3A-dependent manner and ectopic miR-183 promotes metastasis in vivo. Patients with breast cancer with high levels of miR-183 and low levels of SIN3A have the shortest overall survival. Given the critical link between metastasis and survival in patients with breast cancer, it is of utmost importance to identify clinically relevant genes involved in metastasis. Here, we report for the first time the aberrant expression of the putative metastasis suppressing gene SIN3A in human breast cancers and propose a mechanism of SIN3A suppression by miR-183.

IMPLICATIONS

SIN3A expression is decreased in metastatic breast cancer in part due to miR-183.

miR-31 Displays Subtype Specificity in Lung Cancer

miRNA rarely possess pan-oncogenic or tumor-suppressive properties. Most miRNAs function under tissue-specific contexts, acting as either tumor suppressors in one tissue, promoting oncogenesis in another, or having no apparent role in the regulation of processes associated with the hallmarks of cancer. What has been less clear is the role of miRNAs within cell types of the same tissue and the ability within each cell type to contribute to oncogenesis. In this study, we characterize the role of one such tissue-specific miRNA, miR-31, recently identified as the most oncogenic miRNA in lung adenocarcinoma, across the histologic spectrum of human lung cancer. Compared with normal lung tissue, miR-31 was overexpressed in patient lung adenocarcinoma, squamous cell carcinoma, and large-cell neuroendocrine carcinoma, but not small-cell carcinoma or carcinoids. miR-31 promoted tumor growth in mice of xenografted human adenocarcinoma and squamous cell carcinoma cell lines, but not in large- or small-cell carcinoma lines. While miR-31 did not promote primary tumor growth of large- and small-cell carcinoma, it did promote spontaneous metastasis. Mechanistically, miR-31 altered distinct cellular signaling programs within each histologic subtype, resulting in distinct phenotypic differences. This is the first report distinguishing diverse functional roles for this miRNA across the spectrum of lung cancers and suggests that miR-31 has broad clinical value in human lung malignancy. SIGNIFICANCE: These findings demonstrate the oncogenic properties of miR-31 in specific subtypes of lung cancer and highlight it as a potential therapeutic target in these subtypes. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/8/1942/F1.large.jpg.

Identification of Key Genes and Long Noncoding RNA-Associated Competing Endogenous RNA (ceRNA) Networks in Early-Onset Preeclampsia

Background

Preeclampsia (PE) is a pregnancy-specific hypertension syndrome and is one of the leading causes of maternal and perinatal morbidity and mortality. Long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in many diseases, including preeclampsia. The present study is aimed at identifying the key genes and lncRNA-associated competing endogenous RNA (ceRNA) networks in early-onset preeclampsia (EOPE).

Methods

We investigated expression profiles of differentially expressed lncRNAs (DElncRNAs) and genes (DEGs) in placental tissues of EOPE and healthy controls with Human LncRNA Array v4. The potential functions of DEGs and DElncRNAs were predicted using the clusterProfiler package. The lncRNA-mRNA coexpression network was constructed via Pearson's correlation coefficient. The protein-protein interaction (PPI) network of DEGs was constructed, and the hub genes were obtained using the STRING database and Cytoscape. The ceRNA networks were constructed based on miRWalk and LncBase v2. qRT-PCR was performed to confirm the expression of lncRNA MIR193BHG, PROX1-AS1, and GATA3-AS1. ROC curves were performed to assess the clinical value of lncRNA MIR193BHG, PROX1-AS1, and GATA3-AS1 in the diagnosis of EOPE.

Results

We found 6 hub genes (SPP1, CCR2, KIT, ENG, ACKR1, and FLT1) altered in placental tissues of EOPE and constructed a ceRNA network, including 21 lncRNAs, 3 mRNAs, and 69 miRNAs. The expression of lncRNA MIR193BHG and GATA3-AS1 were elevated and showed good clinical values for diagnosing EOPE.

Conclusion

This study provides novel insights into the lncRNA-related ceRNA network in EOPE and identified two lncRNAs as potential prognostic biomarkers in EOPE.

The role of exosomal long non-coding RNAs in cancer drug resistance

One of the major challenges in oncology is drug resistance, which triggers relapse and shortens patients’ survival. In order to promote drug desensitization, cancer cells require the establishment of an ideal tumor microenvironment that accomplishes specific conditions. To achieve this objective, cellular communication is a key factor. Classically, cells were believed to restrictively communicate by ligand-receptor binding, physical cell-to-cell interactions and synapses. Nevertheless, the crosstalk between tumor cells and stroma cells has also been recently reported to be mediated through exosomes, the smallest extracellular vesicles, which transport a plethora of functionally active molecules, such as: proteins, lipids, messenger RNA, DNA, microRNA or long non-coding RNA (lncRNAs). LncRNAs are RNA molecules greater than 200 base pairs that are deregulated in cancer and other diseases. Exosomal lncRNAs are highly stable and can be found in several body fluids, being considered potential biomarkers for tumor liquid biopsy. Exosomal lncRNAs promote angiogenesis, cell proliferation and drug resistance. The role of exosomal lncRNAs in drug resistance affects the main treatment strategies in oncology: chemotherapy, targeted therapy, hormone therapy and immunotherapy. Overall, knowing the molecular mechanisms by which exosomal lncRNA induce pharmacologic resistance could improve further drug development and identify drug resistance biomarkers.