Resveratrol chemosensitizes adriamycin-resistant breast cancer cells by modulating miR-122-5p

Breast cancer is one of the major malignancies threatening women's health worldwide, and chemotherapy tolerance has become a severe limitation of clinical treatment. Recent findings have revealed that resveratrol, as a dietary agent with antitumour activity, could prevent cancer progression by regulating microRNAs (miRNAs). Additionally, dysregulated miRNAs have been found to contribute significantly to chemoresistance by an increasing number of studies. In this study, experiments were designed to study the functional role of resveratrol in MCF-7 cells (low-invasive breast cancer) in chemosensitivity to adriamycin and to determine the targeted miRNAs of resveratrol and their key target proteins linked to cell activity. We demonstrated that in resveratrol-induced chemosensitivity, cell cycle and apoptosis were arrested in adriamycin-resistant breast cancer cells after modulation of the critical suppresser, miR-122-5p. Further miRNA modulation with miR-122-5p mimics or miR-122-5p inhibitors indicated a major effect of miR-122-5p on the regulation of key antiapoptotic proteins (B-cell lymphoma 2 [Bcl-2]) and cyclin-dependent kinases (CDK2, CDK4, and CDK6) in drug-resistant breast cancer cells in response to resveratrol. In conclusion, our results indicate that resveratrol acts as a potential inducer to enhance the chemosensitivity of breast cancer and also suggest that miR-122-5p is involved in the pathway of cell-cycle arrest by targeting Bcl-2 and CDKs.     

Evaluation of exosomal miR-9 and miR-155 targeting PTEN and DUSP14 in highly metastatic breast cancer and their effect on low metastatic cells

Breast cancer is one of the most prevalent cancers in women. Triple-negative breast cancer consists 15% to 20% of breast cancer cases and has a poor prognosis. Cancerous transformation has several causes one of which is dysregulation of microRNAs (miRNAs) expression. Exosomes can transfer miRNAs to neighboring and distant cells. Thus, exosomal miRNAs can transfer cancerous phenotype to distant cells. We used gene expression omnibus (GEO) datasets and miRNA target prediction tools to find overexpressed miRNA in breast cancer cells and their target genes, respectively. Exosomes were extracted from MDA-MB-231 and MCF-7 cells and characterized. Overexpression of the miRNAs of MDA-MB-231 cells and their exosomes were analyzed using quantitative Real-time PCR. The target genes expression was also evaluated in the cell lines. Luciferase assay was performed to confirm the miRNAs: mRNAs interactions. Finally, MCF-7 cells were treated with MDA-MB-231 cells’ exosomes. The target genes expression was evaluated in the recipient cells. GSE60714 results indicated that miR-9 and miR-155 were among the overexpressed miRNAs in highly metastatic triple negative breast cancer cells and their exosomes. Bioinformatic studies showed that these two miRNAs target PTEN and DUSP14 tumor suppressor genes. Quantitative Real-time PCR confirmed the overexpression of the miRNAs and downregulation of their targets. Luciferase assay confirmed that the miRNAs target PTEN and DUSP14. Treatment of MCF-7 cells with MDA-MB-231 cells’ exosomes resulted in target genes downregulation in MCF-7 cells. We found that miR-9 and miR-155 were enriched in metastatic breast cancer exosomes. Therefore, exosomal miRNAs can transfer from cancer cells to other cells and can suppress their target genes in the recipient cells.     

miR-142-3p is a tumor suppressor that inhibits estrogen receptor expression in ER-positive breast cancer

Estrogen receptors (ERs) are involved in the development of many types of malignant tumors, in particular, breast cancer. Among others, ERs affect cell growth, proliferation, and differentiation. The microRNA (miRNA) miR-142-3p has been shown to inhibit carcinogenesis by regulating various cellular processes, including cell cycle progression, cell migration, apoptosis, and invasion. It does so via targeting molecules involved in a range of signaling pathways. We surgically collected 20 ER-positive breast cancer samples, each with matched adjacent normal breast tissue, and measured the expression of miR-142-3p via quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatics methods, luciferase reporter assay, qRT-PCR, and western blot analysis were used to assess whether miR-142-3p could target ESR1, which encodes the estrogen receptor, in ER-positive breast cancer cells and patient samples. We also restored miRNA expression and performed cell viability, cytotoxicity, and colony formation assays. Western blot analysis and qRT-PCR were used to study the expression of apoptosis and stemness markers. We found that miR-142-3p is downregulated in ER-positive breast cancers. Restoration of miR-142-3p expression in ER-positive breast cancer cells reduced cell viability, induced apoptosis via the intrinsic pathway and decreased both colony formation and the expression of stem cell markers. Bioinformatic analysis predicted miR-142-3p could bind to 3′-untranslated region ESR1 messenger RNA (mRNA). Consistently, we demonstrated that miR-142-3p reduced luciferase activity in ER-positive breast cancer cells, and decreased ESR1 expression in both mRNA and protein levels. The results revealed miR-142-3p and ESR1 expression correlated negatively in ER-positive breast cancer samples. The results suggest miR-142-3p acts as a tumor suppressor via multiple mechanisms. Thus, restoration of miR-142-3p expression, for example, via miRNA replacement therapy, may represent an effective strategy for the treatment of ER-positive breast cancer patients.     

miR-1207-5p and miR-1266 suppress gastric cancer growth and invasion by targeting telomerase reverse transcriptase

hTERT is the catalytic subunit of the telomerase complex. Elevated expression of hTERT is associated with the expansion and metastasis of gastric tumor. In this study, we aimed to identify novel tumor suppressor miRNAs that restrain hTERT expression. We began our screen for hTERT-targeting miRNAs with a miRNA microarray. miRNA candidates were further filtered by bioinformatic analysis, general expression pattern in different cell lines, gain-of-function effects on hTERT protein and the potential of these effects to suppress hTERT 3′ untranslated region (3′UTR) luciferase activity. The clinical relevance of two miRNAs (miR-1207-5p and miR-1266) was evaluated by real-time RT-PCR. The effects of these miRNAs on cell growth, cell cycle and invasion of gastric cancer cells were measured with CCK-8, flow cytometry and transwell assays. Finally, the ability of these miRNAs to suppress the transplanted tumors was also investigated. Fourteen miRNAs were identified using a combination of bioinformatics and miRNA microarray analysis. Of these fourteen miRNAs, nine were expressed at significantly lower levels in hTERT-positive cell lines compared with hTERT-negative cell lines and five could downregulate hTERT protein expression. Only miR-1207-5p and miR-1266 interacted with the 3′ UTR of hTERT and the expression levels of these two miRNAs were significantly decreased in gastric cancer tissues. These two miRNAs also inhibited gastric tumor growth in vitro and in vivo. Altogether, miR-1207-5p and miR-1266 were determined to be hTERT suppressors in gastric cancer, and the delivery of these two miRNAs represents a novel therapeutic strategy for gastric cancer treatment.     

Downregulation of exosome-encapsulated miR-548c-5p is associated with poor prognosis in colorectal cancer

The role of circulating exosomal microRNAs (miRNAs) in colorectal cancer (CRC) has drawn more and more attention during the past few years. Previously, we have identified several specific miRNAs in serum exosomes as potential CRC biomarkers. However, little is known about the association between exosome-encapsulated miR-548c-5p and outcomes of patients with CRC. In the current study, the expression of serum exosomal miR-548c-5p was investigated by quantitative real-time polymerase chain reaction. Its correlation with CRC prognosis was estimated by Kaplan-Meier survival and log-rank tests. Cox regression analysis based on uni- and multivariate analyses was performed to estimate the relationship of exosome-encapsulated miR-548c-5p with the clinicopathological factors of patients with CRC. Reduced levels of serum exosomal miR-548c-5p were more significant in CRC patients with liver metastasis and at later TNM stage (III/IV tumor stages). Serum exosomal miR-548c-5p could inhibit the proliferation of CRC cells, while the precise molecular mechanisms warranted further elucidation. In addition, decreased levels of serum exosomal miR-548c-5p were independently associated with shorter overall survival in CRC adjusted by age, sex, tumor grade vascular infiltration, TNM stage (III/IV tumor stages) and metastasis (hazard ratio = 3.40, 95% confidence interval 1.02-11.27; P = 0.046). The downregulation of exosomal miR-548c-5p in serum predicts poor prognosis in patients with CRC. Exosomal miR-548c-5p may be a critical biomarker for CRC diagnosis and prognosis.     

Clinical significance of miR-140-5p and miR-193b expression in patients with breast cancer and relationship to IGFBP5

The functional role of IGFBP5 in breast cancer is complicated. Experimental and bioinformatics studies have shown that IGFBP5 is targeted by miR-140-5p and miR-193b, although this has not yet been proven in clinical samples. The aim of this study was to evaluate the expression of miR-140-5p and miR-193b in breast cancer and adjacent normal tissue and assess its correlation with IGFBP5 and the clinicopathological characteristics of the tumors. IGFBP5 protein expression was analyzed immunohistochemically and IGFBP5, miR-140 and miR-193b mRNA expression levels were analyzed with real-time RT-PCR. Tumor tissue had higher miR-140-5p expression than adjacent normal tissue (p = 0.015). Samples with no immunohistochemical staining for IGFBP5 showed increased miR-140-5p expression (p = 0.009). miR-140-5p expression was elevated in invasive ductal carcinomas (p = 0.002), whereas basal-like tumors had decreased expression of miR-140-5p compared to other tumors (p = 0.008). Lymph node-positive samples showed an approximately 13-fold increase in miR-140-5p expression compared to lymph node-negative tissue (p = 0.049). These findings suggest that miR-140-5p, but not miR-193b, could be an important determinant of IGFBP5 expression and clinical phenotype in breast cancer patients. Further studies are needed to clarify the expressional regulation of IGFBP5 by miR-140-5p.     

miR-17-5p promotes proliferation by targeting SOCS6 in gastric cancer cells

This study aimed to test the exact functions and potential mechanisms of miR-17-5p in gastric cancer. Using real-time PCR, miR-17-5p was found to be expressed more highly in gastric cancer compared with-normal tissues. Gain- and loss-of-function assays demonstrated that miR-17-5p increased the proliferation and growth of gastric cancer cells in vitro and in vivo. Through reporter gene and western blot assays, SOCS6 was shown to be a direct target of miR-17-5p, and proliferative assays confirmed that SOCS6 exerted opposing function to that of miR-17-5p in gastric cancer. In short, miR-17-5p might function as a pro-proliferative factor by repressing SOCS6 in gastric cancer.     

MORC4 is a novel breast cancer oncogene regulated by miR-193b-3p

A better understanding of breast cancer pathogenesis would contribute to improved diagnosis and therapy and potentially decreased mortality rates. Here, we found that the MORC family CW-type zinc finger 4 (MORC4) overexpression in breast cancer tissues is associated with poor survival, and the short-interfering RNA knockdown of MORC4 suppresses the growth of breast cancer cells by promoting apoptosis. To investigate the mechanisms associated with MORC4 upregulation, microRNAs potentially targeting MORC4 were analyzed, with miR-193b-3p identified as the regulator and a negative correlation between miR-193b-3p and MORC4 expression determined in both breast cancer cell lines and tissues. Further analysis verified that MORC4 silencing did not affect miR-193b-3p expression, although altered miR-193b-3p expression attenuated MORC4 protein levels. Moreover, dual-luciferase reporter assays verified miR-193b-3p binding to the 3′ untranslated region of MORC4. Furthermore, restoration of miR-193b-3p expression in breast cancer cells led to decreased growth and activation of apoptosis, which was consistent with results associated with MORC4 silencing in breast cancer cells. These results identified MORC4 as differentially expressed in breast cancer cells and tissues and its downregulation by miR-193b-3p, as well as its roles in regulating the growth of breast cancer cells via regulation of apoptosis. Our findings offer novel insights into potential mechanisms associated with breast cancer pathogenesis.     

A new insight on serum microRNA expression as novel biomarkers in breast cancer patients

Breast cancer (BC) is one of the widespread lethal diseases affecting a large number of women worldwide. As such, employing and identifying significant markers for detecting BC in different stages can assist in better diagnosis and management of the disease. Several diverse markers have been introduced for diagnosis, but their limitations, including low specificity and sensitivity, reduce their application. microRNAs (miRNAs), as short noncoding RNAs, have been shown to significantly influence gene expression in different disease pathologies, especially BC. Clearly, among different samples used for detecting miRNA expressions, circulating miRNAs present as promising and useful biomarkers. Among different body fluid samples, serum serves as one of the most reliable samples, thanks to its high stability under various severe conditions and some unique features. Extensive research has suggested that BC-related miRNAs can remain stable in the serum. The objective of this review is to describe different samples used for detecting miRNAs in BC subjects with emphasis on serum miRNAs. So, this study highlights serum miRNAs with the potential of acting as biomarkers for different stages of BC. We reviewed the possible correlation between potential miRNAs and the risk of early breast cancer, metastatic breast cancer, response to chemotherapy, and relapse.     

MiRNA在乳腺癌转移中的作用

乳腺癌是女性高发的恶性肿瘤之一,远处转移是患者致死的最重要原因。目前乳腺癌转移的具体机制尚未明确。乳腺癌转移相关微RNA(microRNA,miRNA)的发现,为我们研究乳腺癌转移提供了新的思路。miRNA参与包括乳腺癌细胞的生长、凋亡、迁移、侵袭等肿瘤发生、发展过程,进而实现对乳腺癌转移的调控。有些miRNA在乳腺癌转移过程中起促进作用;有些则起抑制作用;还有一些miRNA的功能存在争议。本文将主要着眼于近年来发现的这几类miRNA在乳腺癌转移中所起的作用,并对其将来在乳腺癌诊断、预后判断及治疗中的应用做一综述。     

HOXC13-AS promotes breast cancer cell growth through regulating miR-497-5p/PTEN axis

Dysregulated long noncoding RNAs (lncRNAs) remains to be explored in tumorigenesis. LncRNA HOXC13 antisense RNA (HOXC13-AS) has been found as an oncogene in many cancers; however, the role of HOXC13-AS in breast cancer still elusive. In this study, the HOXC13-AS levels and its role in cell proliferation was first measured by real-time quantitative polymerase chain reaction, Cell Counting Kit-8 assay, and colony formation assay. It showed that HOXC13-AS was increased in breast cancer tissues compared with the adjacent normal tissues and upregulated HOXC13-AS promoted the growth of breast cancer cells. Then, we found that the miR-497-5p levels were downregulated in cancer tissues compared with the adjacent tissues and miR-497-5p suppressed breast cancer cell proliferation. Further study showed that HOXC13-AS could function as a “sponge” for miR-497-5p then suppress miR-497-5p expression. Moreover, we next identified that Phosphatase and Tensin homolog (PTEN) is the target of miR-497-5p. Overexpression of miR-497-5p by chemical mimics decreased the expression of PTEN, while downregulation of miR-497-5p by HOXC13-AS rescued the expression of PTEN. Finally, we showed that HOXC13-AS promoted the proliferation of breast cancer cells and tumor growth through miR-497-5p/PTEN axis in vitro and in vivo. Hence, we conclude that HOXC13-AS, which is significantly upregulated in breast cancers, promoted cell proliferation through the suppressed miR-497-5p and further upregulated PTEN.     

miR-219-5p targets TBXT and inhibits breast cancer cell EMT and cell migration and invasion

miR-219-5p has been reported to act as either a tumor suppressor or a tumor promoter in different cancers by targeting different genes. In the present study, we demonstrated that miR-219-5p negatively regulated the expression of TBXT, a known epithelial–mesenchymal transition (EMT) inducer, by directly binding to TBXT 3′-untranslated region. As a result of its inhibition on TBXT expression, miR-219-5p suppressed EMT and cell migration and invasion in breast cancer cells. The re-introduction of TBXT in miR-219-5p overexpressing cells decreased the inhibitory effects of miR-219 on EMT and cell migration and invasion. Moreover, miR-219-5p decreased breast cancer stem cell (CSC) marker genes expression and reduced the mammosphere forming capability of cells. Overall, our study highlighted that TBXT is a novel target of miR-219-5p. By suppressing TBXT, miR-219-5p plays an important role in EMT and cell migration and invasion of breast cancer cells.