Long non-coding RNA UASR1 promotes proliferation and migration of breast cancer cells through the AKT/mTOR pathway

Coding roles of long non-coding RNAs in breast cancer: Emerging molecular diagnostic biomarkers and potential therapeutic targets with special reference to chemotherapy resistance

Dysregulation of epigenetic mechanisms have been depicted in several pathological consequence such as cancer. Different modes of epigenetic regulation (DNA methylation (hypomethylation or hypermethylation of promotor), histone modifications, abnormal expression of microRNAs (miRNAs), long non-coding RNAs, and small nucleolar RNAs), are discovered. Particularly, lncRNAs are known to exert pivot roles in different types of cancer including breast cancer. LncRNAs with oncogenic and tumour suppressive potential are reported. Differentially expressed lncRNAs contribute a remarkable role in the development of primary and acquired resistance for radiotherapy, endocrine therapy, immunotherapy, and targeted therapy. A wide range of molecular subtype specific lncRNAs have been assessed in breast cancer research. A number of studies have also shown that lncRNAs may be clinically used as non-invasive diagnostic biomarkers for early detection of breast cancer. Such molecular biomarkers have also been found in cancer stem cells of breast tumours. The objectives of the present review are to summarize the important roles of oncogenic and tumour suppressive lncRNAs for the early diagnosis of breast cancer, metastatic potential, and chemotherapy resistance across the molecular subtypes.

LINC00662 enhances cell progression and stemness in breast cancer by MiR-144-3p/SOX2 axis

BACKGROUND

Breast cancer (BC) is one of the most prevalent malignancies among women globally. Emerging evidence indicates that long non-coding RNAs (lncRNAs) are associated with BC carcinogenesis. In the current study, we explored the mechanism by which LINC00662 regulates BC.

METHODS

Quantitative real-time PCR (qRT-PCR) assessed RNA expressions while western blot for protein levels. Kaplan Meier analysis evaluated overall survival (OS). Cytoplasmic/nuclear fractionation, RNA binding protein immunoprecipitation (RIP) and luciferase reporter assays probed into the underlying molecular mechanism of LINC00662 in BC. Xenograft model was established to explore the influence of LINC00662 on BC progression in vivo. R square graphs were utilized to represent RNA relationships.

RESULTS

LINC00662 is overtly overexpressed in BC tissues and cell lines. LINC00662 knockdown hampers cell proliferation, migration, invasion and stemness. LINC00662 expression is negatively correlated with OS of BC patients. LINC00662 up-regulates SOX2 expression by competitively binding to miR-144-3p, thereby modulating BC cell progression. Xenograft experiments verified that LINC00662 promotes BC tumor growth and cell stemness in vivo.

CONCLUSION

LINC00662 enhances cell proliferation, migration, invasion and stemness in BC by targeting miR-144-3p/SOX2 axis. The findings in the present study suggested that LINC00662 could be a potential therapeutic target for BC treatment.

The Role of LncRNAs in Translation

Long non-coding RNAs (lncRNAs), a group of non-protein coding RNAs with lengths of more than 200 nucleotides, exert their effects by binding to DNA, mRNA, microRNA, and proteins and regulate gene expression at the transcriptional, post-transcriptional, translational, and post-translational levels. Depending on cellular location, lncRNAs are involved in a wide range of cellular functions, including chromatin modification, transcriptional activation, transcriptional interference, scaffolding and regulation of translational machinery. This review highlights recent studies on lncRNAs in the regulation of protein translation by modulating the translational factors (i.e, eIF4E, eIF4G, eIF4A, 4E-BP1, eEF5A) and signaling pathways involved in this process as wells as their potential roles as tumor suppressors or tumor promoters.

lncRNA UASR1 is overexpressed in oral squamous cell carcinoma and regulates cancer cell proliferation by regulating miR-375/JAK2 axis

Long non-coding RNAs (lncRNAs) have been confirmed to participate in cancer regulation, including oral squamous cell carcinoma (OSCC). The aim of the present study was to investigate the role of UASR1 in OSCC. The expression levels of UASR1, miR-375 and JAK2 were detected in OSCC tissues by reverse transcriptase quantitative PCR. The targets of UASR1 were predicted by IntaRNA. Colony formation and CCK-8 assays were conducted to estimate cell proliferation. Western blotting was used to detect the protein expression of JAK2. The results demonstrated that UASR1 was upregulated in OSCC tissues compared with non-tumor tissues, and the high level of UASR1 expression was associated with poor overall survival. UASR1 is predicted to interact with miR-375 and the interaction was confirmed by Dual-luciferase activity assay. However, overexpression of UASR1 and miR-375 did not affect the expression of each other. Instead, upregulation of JAK2, a target of miR-375, was observed after the overexpression of UASR1 in OSCC cells. Moreover, overexpression of UASR1 attenuated the inhibitory effects of miR-375 on the expression of JAK2 and cell proliferation. Therefore, UASR1 is overexpressed in OSCC and regulates cancer cell proliferation by regulating the miR-375/JAK2 axis.

LncRNA OIP5-AS1 Promotes Breast Cancer Progression by Regulating miR-216a-5p/GLO1

BACKGROUND

Breast cancer is a familiar malignant tumor, which is a great threat to women's life. Long noncoding RNA Opa interacting protein 5-antisense RNA 1 (OIP5-AS1) has been reported to be associated with numerous cancers. This study aimed to explore the role of OIP5-AS1 and the mechanism of its action in the progression of breast cancer.

METHODS

The expression of OIP5-AS1 and miR-216a-5p was detected by quantitative real-time polymerase chain reaction. Cell proliferation, apoptosis, migration, or invasion was assessed by 4-5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, flow cytometry, or transwell assay, respectively. The binding sites were predicted by bioinformatics tool starBase2.0 (http://starbase.sysu.edu.cn/starbase2/index.php). The interaction between miR-216a-5p and OIP5-AS1 or glyoxalase 1 (GLO1) was confirmed by dual-luciferase reporter assay. The expression of GLO1 was quantified by Western blot. Nude mouse tumorigenicity assays were conducted to verify the role of OIP5-AS1 in vivo.

RESULTS

OIP5-AS1 and GLO1 were highly expressed in both clinical tumor tissues and cell lines, whereas miR-216a-5p was downregulated. Knockdown of OIP5-AS1 suppressed proliferation, migration, and invasion but promoted apoptosis of breast cancer cells. MiR-216a-5p was a target of OIP5-AS1 and interacted with GLO1. MiR-216a-5p inhibition or GLO1 overexpression reversed the effects of OIP5-AS1 knockdown on the development of breast cancer cells. OIP5-AS1 knockdown depleted tumor growth in vivo.

CONCLUSIONS

OIP5-AS1 knockdown suppressed the progression of breast cancer by inducing GLO1 expression via competitively binding to miR-216a-5p, suggesting that OIP5-AS1 was a hopeful biomarker for the therapy of breast cancer.

Long non-coding RNAs in breast cancer metastasis

Breast cancer is the leading cause of cancer-related death among women. Recurrence of primary tumor and metastasis to distant body parts are major causes of breast cancer-associated mortality. The 5-year survival rate for women with metastatic breast cancer is only 25-30%. Breast cancer metastasis is a series of processes involved with EMT, invasion, loss of cell to cell adhesion, alteration in cell phenotype, extravasation, microenvironment of the tumor, and colonization to the secondary sites. Epigenetic modification is involved in the transformation of the distant stromal cell into a secondary tumor. LncRNAs, are one the key epigenetic modifiers, are the largest endogenous non-coding RNAs with approximate base-pair lengths from 200 nt to 100 kb. LncRNA plays a crucial role in breast cancer metastasis by sponging miRNA, by degrading or silencing specific mRNA, or else by targeting the enzymes and microprocessor subunits involved in the biogenesis of miRNA. LncRNA also alters the expression of several genes involved in breast cancer metastasis and modulating different cell signaling pathways. The goal of this review is to provide a better understanding of the role of lncRNA in the regulation of breast cancer metastasis. We also summarized some of the key lncRNAs that regulate the genes and signaling pathways involved in breast cancer invasion and metastasis.

lncRNA UASR1 sponges miR-107 in colorectal cancer to upregulate oncogenic CDK8 and promote cell proliferation

lncRNA UASR1 (UASR1) has been characterized as an oncogenic lncRNA in breast cancer. UASR1 was predicted to interact with miR-107, which serves tumor suppressive roles mainly by targeting CDK8. The present study was performed to investigate the interactions among UASR1, miR-107 and CDK8 in colorectal cancer (CRC). A total of 62 patients with CRC, including 40 males and 22 females (age range, 38-67 years; mean age, 57.2±7.6 years) were enrolled at the Second Hospital of Shandong University between July 2012 and July 2014. The expression of UASR1 in tissues and cells were detected by reverse transcription-quantitative polymerase chain reaction. The interaction between UASR1 and miR-107 was investigated by performing dual luciferase activity assay, and the effects of overexpression of UASR1, miR-107 and CDK8 on the proliferation of CR4 cells were analyzed by performing cell proliferation analysis. It was observed that UASR1 is upregulated in CRC and its high expression levels predicted poor survival in patients with CRC. RNA-RNA interaction prediction demonstrated that UASR1 may interact with miR-107. In CRC cells, overexpression of UASR1 and miR-107 did not affect each other. However, the expression of CDK8, a target of miR-107, was upregulated following overexpression of UASR1. Notably, overexpression of UASR1 decreased the inhibitory effects of miR-107 on cell proliferation and the expression of CDK8. Therefore, UASR1 may sponge miR-107 to upregulate oncogenic CDK8, thereby promoting CRC cell proliferation.

Long non-coding RNA-based signatures to improve prognostic prediction of breast cancer

Breast cancer (BC) is a disease of high mortality rate because of high malignant, while early diagnosis and personal management may make a better prognosis possible. This study aimed to establish and validate lncRNAs signatures to improve the prognostic prediction for BC.RNA sequencing data along with the corresponding clinical information of patients with BC were gained from The Cancer Genome Atlas (TCGA). Prognostic differentially expressed lncRNAs were obtained using differentially expressed lncRNAs analysis (P value <.01 and |fold change| > 2) and univariate cox regression (P value <.05). By applying least absolute shrinkage and selection operation (LASSO) Cox regression analysis along with 10-fold cross-validation, 2 lncRNA-based signatures were constructed in the training, test and whole set.A 14-lncRNAs signature and a 10-lncRNAs signature were built for overall survival (OS) and relapse-free survival (RFS) respectively in the 3 sets. BC patients were divided into high-risk groups and low-risk groups depended on median risk score value. Significant differences were found for OS and RFS between 2 groups in the 3 sets. The time-dependent receiver operating characteristic (ROC) curves analysis demonstrated that our lncRNAs signatures had better predictive capacities of survival and recurrence for BC patients as well as enhancing the predictive ability of the tumor node metastasis (TNM) stage system.These results indicate that the 2 lncRNAs signatures with the potential to be biomarkers to predict the prognosis of BC for OS and RFS.

Regulation of Breast Cancer Progression by Noncoding RNAs

BACKGROUND

Breast cancer (BC) is the cardinal cause of cancer-related deaths among women across the globe. Our understanding of the molecular mechanisms underlying BC invasion and metastasis remains insufficient. Recent studies provide compelling evidence on the prospective contribution of noncoding RNAs (ncRNAs) and the association of different interactive mechanisms between these ncRNAs with breast carcinogenesis. MicroRNAs (small ncRNAs) and lncRNAs (long ncRNAs) have been explored extensively as classes of ncRNAs in the pathogenesis of several malignancies, including BC.

OBJECTIVE

In this review, we aim to provide a better understanding of the involvement of miRNAs and lncRNAs and their underlying mechanisms in BC development and progression that may assist the development of monitoring biomarkers and therapeutic strategies to effectively combat BC.

CONCLUSION

These ncRNAs play critical roles in cell growth, cell cycle regulation, epithelialmesenchymal transition (EMT), invasion, migration, and apoptosis among others, and were observed to be highly dysregulated in several cancers. The miRNAs and lncRNAs were observed to interact with each other through several mechanisms that governed the expression of their respective targets and could act either as tumor suppressors or as oncogenes, playing a crucial part in breast carcinogenesis.

Long noncoding RNA GAS6-AS2 sponges microRNA-493, thereby enhancing the malignant characteristics of breast cancer cells via upregulation of FUT4

Long noncoding RNA (lncRNA) GAS6-AS2 serves as an oncogenic lncRNA in various types of human cancer. In this study, we attempted to examine the functions of GAS6-AS2 in breast cancer (BC) and explore the potential mechanisms involved. Reverse-transcription quantitative PCR was carried out to determine GAS6-AS2 expression in BC tissues and cell lines. Multiple functional experiments, including a Cell Counting Kit-8 assay, Transwell migration and invasion assays, and an in vivo nude-mouse xenograft experiment, were conducted to evaluate the effects of GAS6-AS2 in BC cells. GAS6-AS2 expression was high in BC tumors, manifesting a strong correlation with tumor size, lymph node metastasis, TNM stage, and shorter overall survival in patients with BC. A knockdown of GAS6-AS2 restricted BC cell proliferation, migration, and invasion in vitro and retarded tumor growth in vivo. With regard to its mechanism, GAS6-AS2 acted as a competing endogenous RNA that sponged microRNA-493 (miR-493), thereby increasing the expression of fucosyltransferase IV (FUT4). Either miR-493 inhibition or FUT4 upregulation abrogated the consequences of GAS6-AS2 knockdown in BC cells. These results revealed that GAS6-AS2 sponges miR-493 to enhance the malignant characteristics of BC in vitro and in vivo by increasing FUT4 expression. Thus, this lncRNA is an effective therapeutic target in BC and a promising diagnostic biomarker of this cancer.