Expression and potential molecular mechanisms of miR‑204‑5p in breast cancer, based on bioinformatics and a meta‑analysis of 2,306 cases

Potential therapies for non-coding RNAs in breast cancer

Breast cancer (BC) is one of the frequent tumors that seriously endanger the physical and mental well-being in women with strong heterogeneity, and its pathogenesis involves multiple risk factors. Depending on the type of BC, hormonal therapy, targeted therapy, and immunotherapy are the current systemic treatment options along with conventional chemotherapy. Despite significant progress in understanding BC pathogenesis and therapeutic options, there is still a need to identify new therapeutic targets and develop more effective treatments. According to recent sequencing and profiling studies, non-coding (nc) RNAs genes are deregulated in human cancers via deletion, amplification, abnormal epigenetic, or transcriptional regulation, and similarly, the expression of many ncRNAs is altered in breast cancer cell lines and tissues. The ability of single ncRNAs to regulate the expression of multiple downstream gene targets and related pathways provides a theoretical basis for studying them for cancer therapeutic drug development and targeted delivery. Therefore, it is far-reaching to explore the role of ncRNAs in tumor development and their potential as therapeutic targets. Here, our review outlines the potential of two major ncRNAs, long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) as diagnostic and prognostic biomarkers as well as targets for new therapeutic strategies in breast cancer.

The Overexpressed MicroRNAs miRs-182, 155, 493, 454, and U6 snRNA and Underexpressed let-7c, miR-328, and miR-451a as Potential Biomarkers in Invasive Breast Cancer and Their Clinicopathological Significance

INTRODUCTION

Breast cancer comprises the leading cause of cancer-related death in women. MicroRNAs (miRNAs) have emerged as important factors with concern to carcinogenesis and have potential for use as biomarkers.

METHODS

This study provides a comprehensive evaluation of the microRNA expression in invasive breast carcinoma of no special type tissues compared with benign tissues via large-scale screening and the candidate-specific validation of 15 miRNAs and U6 snRNA applying qPCR and the examination of clinicopathological data.

RESULTS

Of the six downregulated miRNAs, let-7c was identified as the most promising miRNA biomarker and its lower expression was linked with Ki-67 positivity, luminal B versus luminal A samples, multifocality, lymph node metastasis, and inferior PFS. Of the 9 upregulated sncRNAs, the data on U6 snRNA, miR-493 and miR-454 highlighted their potential oncogenic functions. An elevated U6 snRNA expression was associated with the tumor grade, Ki-67 positivity, luminal B versus A samples, lymph node metastasis, and worsened PFS (and OS) outcomes. An elevated miR-454 expression was detected in higher grades, Ki-67 positive and luminal B versus A samples. Higher miR-493 levels were noted for the tumor stage (and grade) and worse patient outcomes (PFS, OS). The data also suggested that miR-451a and miR-328 may have tumor suppressor roles, and miR-182 and miR-200c pro-oncogenic functions, while the remaining sncRNAs did not evince any significant associations.

CONCLUSION

We showed particular microRNAs and U6 snRNA as differentially expressed between tumors and benign tissues and associated with clinicopathological parameters, thus potentially corresponding with important roles in breast carcinogenesis. Their importance should be further investigated and evaluated in follow-up studies to reveal their potential in clinical practice.

miR-204-5p Hampers Breast Cancer Malignancy and Affects the Cell Cycle by Targeting PRR11

PURPOSE

To unravel mechanisms of miR-204-5p in breast cancer (BC) cells.

METHODS

miR-204-5p expression level in BC cell lines was measured by qRT-PCR. Putative binding sites of miR-204-5p on the 3'-untranslated region of PRR11 were predicted by the bioinformatics method and verified by the dual-luciferase method. Protein and mRNA levels of PRR11 in BC were determined by western blot and qRT-PCR. The association between two genes was analyzed by correlation analysis. Cancer cell functions were evaluated through CCK8, flow cytometry, and Transwell approaches.

RESULTS

Significant downregulation of miR-204-5p was observed in BC tissue and cells. Cell functional experiments showed the inhibition of miR-204-5p on cell behaviors and cell cycle. PRR11 was the downstream target of miR-204-5p. Inhibition of RPP11 could reverse the impacts of the miR-204-5p inhibitor on cell functions of BC.

CONCLUSION

Our study revealed that the miR-204-5p/PRPP11 axis suppressed BC progression, which may provide a novel insight into the regulatory roles of miR-204-5p.

Clinical significance and effect of lncRNA BBOX1-AS1 on the proliferation and migration of lung squamous cell carcinoma

Long non-coding RNAs (lncRNAs) have a role in the occurrence and development of lung squamous cell carcinoma (LUSC). lncRNA γ-butyrobetaine hydroxylase 1 (BBOX1)-antisense 1 (AS1) may contribute to disease development. However, there are no studies on the role of BBOX1-AS1 in LUSC to date. In the present study, an in-house gene microarray analysis was performed to detect the differentially expressed lncRNAs and mRNAs between three pairs of LUSC and normal lung tissues. Only one lncRNA, BBOX1-AS1, was differentially expressed in the in-house microarray and The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and ArrayExpress databases. Reverse transcription-quantitative PCR (RT-qPCR) was then performed and the original RNA-sequencing data from the TCGA, GEO and ArrayExpress datasets were used to determine the expression and clinical value of BBOX1-AS1 in LUSC. In addition, a Cell Counting Kit-8 assay, cell cycle analysis and scratch assay were performed to explore whether BBOX1-AS1 expression affected the proliferation and migration of LUSC cells in vitro. The results of the RT-qPCR analysis and data obtained from the TCGA database, GEO datasets, in-house gene microarray and standard mean deviation analysis all supported the upregulated expression level of BBOX1-AS1 in LUSC. Furthermore, silencing of BBOX1-AS1 inhibited the proliferation and migration of LUSC cells according to in vitro assays. In addition, the cells were arrested in S-phase after knockdown of BBOX1-AS1. In conclusion, the expression level of BBOX1-AS1 was upregulated in LUSC tissues. BBOX1-AS1 may exert an oncogenic effect on LUSC by regulating various biological functions. However, additional functional experiments should be performed to verify the exact mechanism.

Astragalus polysaccharide attenuates metabolic memory-triggered ER stress and apoptosis via regulation of miR-204/SIRT1 axis in retinal pigment epithelial cells

Background: ‘Metabolic memory’ of early hyperglycaemic environment has been frequently suggested in the progression of diabetic retinopathy (DR). Retinal pigment epithelial (RPE) cells are crucial targets for DR initiation following hyperglycaemia. Astragalus polysaccharides (APS) has been long used as a traditional Chinese medicine in treating diabetes. In the present study, the preventive effects and mechanisms of APS on metabolic memory-induced RPE cell death were investigated.

Methods: The expressions of miR-204 and SIRT1 were determined by reverse transcription quantitative PCR (RT-qPCR). Dual luciferase assay was applied to detect the potential targeting effects of miR-204 on SIRT1. SIRT1, ER stress and apoptosis related proteins were monitored using Western blotting. Apoptosis was assessed by TUNEL assay and Annexin V/PI staining followed by flow cytometry analysis. MiR-204 mimics and shSIRT1 were applied for miR-204 overexpression and SIRT1 knockdown, respectively.

Results: High glucose exposure induced metabolic memory, which was accompanied with sustained dysregulation of miR-204/SIRT1 axis, high level of ER stress and activation of apoptotic pathway even after replacement with normal glucose. Pre-treatment with APS concentration-dependently reversed miR-204 expression, leading to disinhibition of SIRT1 and alleviation of ER stress-induced apoptosis indicated by decreased levels of p-PERK, p-IRE-1, cleaved-ATF6, Bax, cleaved caspase-12, -9, -3, and increased levels of Bcl-2 and unleaved PARP. The effects of APS on RPE cells were reversed by either miR-204 overexpression or SIRT1 knockdown.

Conclusions: We concluded that APS inhibited ER stress and subsequent apoptosis via regulating miR-204/SIRT1 axis in metabolic memory model of RPE cells.