LncRNA LET function as a tumor suppressor in breast cancer development

The expression and function of long noncoding RNAs in hepatocellular carcinoma

With the deepening of the genome project study, attention on noncoding RNAs is increasing. Long noncoding RNAs (lncRNAs) have become a new research hotspot. A growing number of studies have revealed that lncRNAs are involved in tumorigenesis and tumor suppressor pathways. Aberrant expressions of lncRNAs have been found in a variety of human tumors including hepatocellular carcinoma (HCC). In this review, we provide a brief introduction to lncRNA and highlight recent research on the functions and clinical significance of lncRNAs in HCC.

NR2F1-AS1 Acts as an Oncogene in Breast Cancer by Competitively Binding with miR-641

BACKGROUND

Long noncoding RNA (lncRNA) NR2F1-AS1 has been previously reported to be dysregulated in human cancers and implicated in the tumorigenesis and development of tumors. In this research, we detected the expression level and biological function of NR2F1-AS1 in breast cancer (BC).

METHODS

The expression of NR2F1-AS1 in BC tissues and cell lines was determined by qRT-PCR analysis. The associations of NR2F1-AS1 expression with clinical characteristics and survival rate of BC patients were also analyzed. Cell proliferation, migration, and invasion were measured by the CCK-8 and Transwell assay.

RESULTS

The results revealed that the total survival time of BC patients with high NR2F1-AS1 expression was lower than that of BC patients with low NR2F1-AS1 expression. Moreover, functional experiments demonstrated that knockdown of NR2F1-AS1 inhibited BC cell viability, migration, and invasion abilities, whereas overexpression of NR2F1-AS1 had the opposite effect. Mechanistic investigation revealed that NR2F1-AS1 can competitively bind with microRNA-641 (miR-641) in BC. These results revealed that NR2F1-AS1 functioned as an oncogene by sponging miR-641 expression in BC cell progression. Moreover, miR-641 was negatively correlated with NR2F1-AS1 in BC tissues.

CONCLUSION

Hence, NR2F1-AS1 was found to act as an oncogene in breast cancer by suppressing miR-641. We suggested that NR2F1-AS1 could be a potential biomarker for BC diagnosis and therapy.

KRAS-related long noncoding RNAs in human cancers

KRAS is one of the most widely prevalent proto-oncogenes in human cancers. The constitutively active KRAS oncoprotein contributes to both tumor onset and cancer development by promoting cell proliferation and anchorage-independent growth in a MAPK pathway-dependent manner. The expression of microRNAs (miRNAs) and the KRAS oncogene are known to be dysregulated in various cancers, while long noncoding RNAs (lncRNAs) can act as regulators of the miRNAs targeting KRAS oncogene in different cancers and have gradually become a focus of research in recent years. In this review article, we summarize recent advances in the research on lncRNAs that have sponging effects on KRAS-targeting miRNAs as crucial mediators of KRAS expression in different cell types and organs. A deeper understanding of lncRNA function in KRAS-driven cancers is of major fundamental importance and will provide a valuable clinical tool for the diagnosis, prognosis, and eventual treatment of cancers.

Construction of liver hepatocellular carcinoma-specific lncRNA-miRNA-mRNA network based on bioinformatics analysis

Liver hepatocellular carcinoma (LIHC) is one of the major causes of cancer-related death worldwide with increasing incidences, however there are very few studies about the underlying mechanisms and pathways in the development of LIHC. We obtained LIHC samples from The Cancer Genome Atlas (TCGA) to screen differentially expressed mRNAs, lncRNAs, miRNAs and driver mutations. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, Gene ontology enrichment analyses and protein–protein interaction (PPI) network were performed. Moreover, we constructed a competing endogenous lncRNAs-miRNAs-mRNAs network. Finally, cox proportional hazards regression analysis was used to identify important prognostic differentially expressed genes. Total of 1284 mRNAs, 123 lncRNAs, 47 miRNAs were identified within different tissues of LIHC patients. GO analysis indicated that upregulated and downregulated differentially expressed mRNAs (DEmRNAs) were mainly associated with cell division, DNA replication, mitotic sister chromatid segregation and complement activation respectively. Meanwhile, KEGG terms revealed that upregulated and downregulated DEmRNAs were primarily involved in DNA replication, Metabolic pathways, cell cycle and Metabolic pathways, chemical carcinogenesis, retinol metabolism pathway respectively. Among the DERNAs, 542 lncRNAs-miRNAs-mRNAs pairs were predicted to construct a ceRNA regulatory network including 35 DElncRNAs, 26 DEmiRNAs and 112 DEmRNAs. In the Kaplan‐Meier analysis, total of 43 mRNAs, 14 lncRNAs and 3 miRNAs were screened out to be significantly correlated with overall survival of LIHC. The mutation signatures were analyzed and its correlation with immune infiltrates were evaluated using the TIMER in LIHC. Among the mutation genes, TTN mutation is often associated with poor immune infiltration and a worse prognosis in LIHC. This work conducted a novel lncRNAs-miRNAs-mRNAs network and mutation signatures for finding potential molecular mechanisms underlying the development of LIHC. The biomarkers also can be used for predicting prognosis of LIHC.

lncRNA MT1JP Suppresses Biological Activities of Breast Cancer Cells in vitro and in vivo by Regulating the miRNA-214/RUNX3 Axis

Introduction

The purpose of our research was to evaluate MT1JP in breast cancer.

Material and Methods

For clinical purpose, tissues were collected, and a correlation analysis ofMT1JP and miRNA-214 gene expressions was conducted. Using an in vitro study, MDA-MB-231 and MCF-7 cell lines were used as research objects in our research. Colony, flow cytometry, TUNEL, transwell, adhesion and wound healing assay were used to discuss the biological activities of the cells. In an in vivo study, tumor weight and volume were measured, and cell apoptosis was measured by TUNEL assay. The relative mechanism's proteins were evaluated by Western blotting or immunohistochemistry assay.

Results

Compared with adjacent tissues, MT1JP and miRNA-214 gene expressions were significantly different (P<0.001, respectively). By in vitro and in vivo studies, the biological activities of the cells were significantly decreased in MDA-MB-231 and MCF-7 cell lines with MT1JP overexpression. The relative mechanism was correlated with miRNA-214/RUNX3 axis.

Conclusion

The overexpression of MT1JP suppresses the biological activities of breast cancer cells by regulation miRNA-214/RUNX3 axis in vitro and vivo study.

The Role of microRNAs, Long Non-coding RNAs, and Circular RNAs in Cervical Cancer

Prolonged infection of uterine cervix epithelium with human papillomavirus (HPV) and constitutive expression of viral oncogenes have been recognized as the main cause of the complex molecular changes leading to transformation of cervical epithelial cells. Deregulated expression of microRNAs (miRNA), long non-coding RNAs (lncRNA), and circular RNAs (circRNA) is involved in the initiation and promotion processes of cervical cancer development. Expression profiling of small RNAs in cervical neoplasia revealed up-regulated “oncogenic” miRNAs, such as miR-10a, miR-21, miR-19, and miR-146a, and down regulated “tumor suppressive” miRNAs, including miR-29a, miR-372, miR-214, and miR-218, associated with cell growth, malignant transformation, cell migration, and invasion. Also several lncRNAs, comprising among others HOTAIR, MALAT1, GAS5, and MEG3, have shown to be associated with various pathogenic processes such as tumor progression, invasion as well as therapeutic resistance and emerged as new diagnostic and prognostic biomarkers in cervical cancer. Moreover, human genes encoded circular RNAs, such as has_circ-0018289, have shown to sponge specific miRNAs and to concur to the deregulation of target genes. Viral encoded circE7 has also demonstrated to overexpress E7 oncoprotein thus contributing to cell transformation. In this review, we summarize current literature on the complex interplay between miRNAs, lncRNAs, and circRNAs and their role in cervical neoplasia.

Long-chain non-coding RNA GACAT1 promotes development and progression of breast cancer by targeting microRNA-875-3p

Role of long-chain non-coding ribonucleic acid (lncRNA) GACAT1 in the development of breast cancer and its possible mechanism were investigated. The levels of GACAT1, microRNA-875-3p and Stonin2 (STON2) in breast cancer tissues and adjacent normal tissues were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The level of GACAT1 in breast cancer cell lines was further explored. The effects of GACAT1 and microRNA-875-3p on cell proliferation and cycle were detected by cell counting kit-8 (CCK-8) and flow cytometry. The binding relationship between microRNA-875-3p and STON2, microRNA-875-3p and GACAT1 was examined by a dual luciferase reporting assay. It was confirmed by rescue experiments whether GACAT1 canregulate the level of STON2 by binding to microRNA-875-3p. GACAT1 level was clearly enhanced in breast cancer tissues compared to that of the adjacent tissues. Similar result was observed in breast cancer cell lines. Upregulation of GACAT1 promoted the proliferation and cycle of breast cancer cells including MCF-7 and BCap-37. The dual luciferase reporting assay results indicated that GACAT1 had a binding relationship with microRNA-875-3p. Further experiments confirmed that microRNA-875-3p was conspicuously downregulated in breast cancer tissues, and upregulation of microRNA-875-3p could inhibit the proliferation ability of MCF-7 and BCap-37 cells, and partially reversed the promoting effect of GACAT1 on cell cycle. Through bioinformatics prediction and dual luciferase reporter gene experiments, we found that STON2 might be a target gene of microRNA-875-3p. Overexpression of STON2 could partially abolish the effect of microRNA-875-3p on cell proliferation and cycle of MCF-7 and BCap-37 cells. GACAT1 can participate in the progression of breast cancer by promoting the proliferation and cycle of breast cancer cells. The mechanism may be through the regulation of the level of STON2 by adsorbing microRNA-875-3p.

Long Non-Coding RNA: Dual Effects on Breast Cancer Metastasis and Clinical Applications

As a highly heterogeneous malignancy, breast cancer (BC) has become the most significant threat to female health. Distant metastasis and therapy resistance of BC are responsible for most of the cases of mortality and recurrence. Distant metastasis relies on an array of processes, such as cell proliferation, epithelial-to-mesenchymal transition (EMT), mesenchymal-to-epithelial transition (MET), and angiogenesis. Long non-coding RNA (lncRNA) refers to a class of non-coding RNA with a length of over 200 nucleotides. Currently, a rising number of studies have managed to investigate the association between BC and lncRNA. In this study, we summarized how lncRNA has dual effects in BC metastasis by regulating invasion, migration, and distant metastasis of BC cells. We also emphasize that lncRNA has crucial regulatory effects in the stemness and angiogenesis of BC. Clinically, some lncRNAs can regulate chemotherapy sensitivity in BC patients and may function as novel biomarkers to diagnose or predict prognosis for BC patients. The exact impact on clinical relevance deserves further study. This review can be an approach to understanding the dual effects of lncRNAs in BC, thereby linking lncRNAs to quasi-personalized treatment in the future.

New Insights into the Implication of Epigenetic Alterations in the EMT of Triple Negative Breast Cancer

Breast cancer is the most common cancer and leading cause of cancer death among women worldwide, encompassing a wide heterogeneity of subtypes with different clinical features. During the last two decades, the use of targeted therapies has emerged in clinical research in order to increase treatment efficiency, improve prognosis and reduce recurrence. However, the triple negative breast cancer (TNBC) subtype remains a clinical challenge, with poor prognosis since no therapeutic targets have been identified. This aggressive breast cancer entity lacks expression of oestrogen receptor (ER) and progesterone receptor (PR), and it does not overexpress human epidermal growth factor receptor 2 (HER2). The major reason for TNBC poor prognosis is early therapeutic escape from conventional treatments, leading to aggressive metastatic relapse. Metastases occur after an epithelial-mesenchymal transition EMT of epithelial cells, allowing them to break free from the primary tumour site and to colonize distant organs. Cancer-associated EMT consists not only of acquired migration and invasion ability, but involves complex and comprehensive reprogramming, including changes in metabolism, expression levels and epigenetic. Recently, many studies have considered epigenetic alterations as the primary initiator of cancer development and metastasis. This review builds a picture of the epigenetic modifications implicated in the EMT of breast cancer. It focuses on TNBC and allows comparisons with other subtypes. It emphasizes the role of the main epigenetic modifications lncRNAs, miRNAs, histone and DNA- modifications in tumour invasion and appearance of metastases. These epigenetic alterations can be considered biomarkers representing potential diagnostic and prognostic factors in order to define a global metastatic signature for TNBC.