Downregulation of miR-92a is associated with aggressive breast cancer features and increased tumour macrophage infiltration

Reciprocal control of miR-197 and IL-6/STAT3 pathway reveals miR-197 as potential therapeutic target for hepatocellular carcinoma

Signal transducer and activator of transcription 3 (STAT3) is one of the key players in liver cancer. Increased levels of phosphorylated STAT3 (p-STAT3) have been detected in many cancers including hepatocellular carcinoma (HCC), and are usually associated with a more aggressive phenotype and poor prognosis. In addition to aberrant activation of STAT3, upregulation of total STAT3 was also detected in HCC, for which the underlying mechanisms and significance remain to be fully elucidated. Here we report that a reciprocal regulation exists between miR-197 and the IL-6/STAT3 inflammatory signaling pathway in HCC. We found that IL-6 stimulation increased total STAT3 expression at protein level but not mRNA level in HCC cells, suggesting the existence of post-transcriptional regulation of STAT3. Our study showed that IL-6/STAT3 pathway decreases expression of miR-197 in HCC, which amplifies IL-6/STAT3 pathway and contributes to HCC progression. miR-197 can significantly inhibit HCC growth both in vitro and in vivo. In addition, IL-6/STAT3-induced downregulation of miR-197 in HCC may be via affecting Drosha binding to primary miR-197 (pri-miR-197) and thus reducing mature miR-197 generation. Our study suggests that miR-197 may serve as a potential therapeutic target for interfering with the IL-6/STAT3 inflammatory pathway in HCC.

MicroRNAs as mediators and communicators between cancer cells and the tumor microenvironment

Cancer cells grow in an environment comprised of multiple components that support tumor growth and contribute to therapy resistance. Major cell types in the tumor microenvironment are fibroblasts, endothelial cells and infiltrating immune cells all of which communicate with cancer cells. One way that these cell types promote cancer progression is by altering the expression of microRNAs (miRNAs), small noncoding RNAs that negatively regulate protein expression, either in the cancer cells or in the associated normal cells. Changes in miRNA expression can be brought about by direct interaction between the stromal cells and cancer cells, by paracrine factors secreted by any of the cell types or even through direct communication between cells through secreted miRNAs. Understanding the role of miRNAs in the complex interactions between the tumor and cells in its microenvironment is necessary if we are to understand tumor progression and devise new treatments.

miR-92a is upregulated in cervical cancer and promotes cell proliferation and invasion by targeting FBXW7

MicroRNAs (miRNAs) are involved in the cervical carcinogenesis and progression. In this study, we investigated the role of miR-92a in progression and invasion of cervical cancer. MiR-92a was significantly upregulated in cervical cancer tissues and cell lines. Overexpression of miR-92a led to remarkably enhanced proliferation by promoting cell cycle transition from G1 to S phase and significantly enhanced invasion of cervical cancer cells, while its knockdown significantly reversed these cellular events. Bioinformatics analysis suggested F-box and WD repeat domain-containing 7 (FBXW7) as a novel target of miR-92a, and miR-92a suppressed the expression level of FBXW7 mRNA by direct binding to its 3'-untranslated region (3'UTR). Expression of miR-92a was negatively correlated with FBXW7 in cervical cancer tissues. Furthermore, Silencing of FBXW7 counteracted the effects of miR-92a suppression, while its overexpression reversed oncogenic effects of miR-92a. Together, these findings indicate that miR-92a acts as an onco-miRNA and may contribute to the progression and invasion of cervical cancer, suggesting miR-92a as a potential novel diagnostic and therapeutic target of cervical cancer.

microRNAs: a new class of breast cancer biomarkers

MicroRNAs (miRNAs) are regulatory molecules known to be aberrantly expressed in cancer and contribute to numerous aspects of tumor biology including the initiation, growth and spread of the tumor. With such diverse roles, it is becoming apparent that some may also provide valuable information which may be of use in a clinical setting, demonstrating the potential to act as both screening tools for the stratification of high-risk patients, while informing the treatment decision-making process. There is mounting evidence to suggest that some miRNAs may even provide assistance in the diagnosis of patients with breast cancer. In addition, miRNAs may themselves be considered therapeutic targets, with inhibition or reintroduction of a particular miRNA capable of inducing a response in vivo. This review focuses on miRNAs that have prognostic, diagnostic or predictive potential in breast cancer as well as the possible challenges in the translation of such observations to the clinic.

microRNA levels in paraffin-embedded indolent B-cell non-Hodgkin lymphoma tissues from patients chronically infected with hepatitis B or C virus

Background

Epidemiological evidence links Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) to B-cell non-Hodgkin lymphoma (B-NHL). These B-NHLs, particularly those associated with HCV, may represent a distinct sub-group with peculiar molecular features, including peculiar expression of microRNAs (miRs).

The aim of the present study was to search for miRs whose level in indolent B-NHL tissues could be associated with HBV or HCV infection.

Methods

Fourteen formalin fixed paraffin embedded (FFPE) tissues from HBV+, HCV+ and HBV-/HCV- indolent B-NHL patients were analyzed for levels of 34 selected miRs by quantitative Real-Time PCR. Reactive lymph nodes (RLNs) from HBV-/HCV- patients were included as non-tumor control. Statistical analysis of output data included Pearson and Spearman correlation and Mann-Whitney test and were carried out by the STATA software.

Results

MiR-92a was decreased exclusively in HBV-/HCV- B-NHLs, while miR-30b was increased in HBV+ and HCV+ samples, though only the HCV+ achieved full statistical significance. Analysis of a small subset of B-NHLs belonging to the same histological subtype (Nodal Marginal Zone Lymphoma) highlighted three miRs associated with HCV infection (miR-223, miR-29a and miR-29b) and confirmed decreased level of miR-92a in HBV-/HCV- samples also when considering this restricted B-NHL group.

Conclusions

Although caution is needed due to the limited number of analyzed samples, overall the results suggest that differences at the miR expression level exist between indolent B-NHLs developed in patients with or without HBV or HCV infection. The identification of three further miRs associated with HCV by analyzing histologically homogeneous samples suggests that variations of miR levels possibly associated with HBV or HCV may be obscured by the tissue-specific variability of miR level associated with the different histological subtypes of B-NHL. Thus, the identification of further miRs will require, in addition to an increased sample size, the comparison of B-NHL tissues with the same histological classification.

MicroRNA-218 is upregulated in gastric cancer after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy and increases chemosensitivity to cisplatin

AIM: To investigate the molecular mechanisms of miRNA in advanced gastric cancers (AGCs) before and after cytoreductive surgery (CRS) + hyperthermic intraperitoneal chemotherapy (HIPEC).

METHODS: A miRNA microarray containing human mature and precursor miRNA sequences was used to compare expression profiles in serum samples of 5 patients with AGC before and after CRS + HIPEC. The upregulation of miR-218 was confirmed by real-time reverse transcription polymerase chain reaction and its expression was analyzed in SGC7901 gastric cancer cells.

RESULTS: miRNA microarray chip analysis found that the level of miR-218 expression was upregulated more than 8 fold after CRS + HIPEC. Furthermore, miR-218 increased gastric cancer cell chemosensitivity to cisplatin in vitro and inhibited gastric cell tumor growth in nude mice in vivo (0.5 vs 0.78, P < 0.05).

CONCLUSION: Our results indicated that targeting miR-218 may provide a strategy for blocking the development of gastric cancer and reverse the multi-drug resistance of gastric cell lines.

MicroRNA-18a inhibits hypoxia-inducible factor 1α activity and lung metastasis in basal breast cancers

Introduction

In breast cancer, distinct expression profiles of microRNAs (miRNAs) have been associated with molecular subgroups and clinicopathological characteristics, implicating a diagnostic and prognostic role of miRNAs. However, the biological functions of deregulated miRNAs in tumor progression are not yet completely defined. In this study, we investigated the function of miR-18a in regulating breast cancer metastasis through the hypoxia-inducible factor 1α (HIF1A)–dependent hypoxic response.

Methods

An orthotopic metastatic breast cancer xenograft model (MDA-MB-231 cells) was used to identify miRNAs associated with spontaneous lung metastasis. The function of miR-18a in regulating HIF1A expression, as well as cellular responses to hypoxia and metastasis, were then studied in vitro and in vivo by assessing ectopic miR-18a expression or miR-18a inhibition. miRNA–mRNA interactions (AGO2 immunoprecipitation and 3′ untranslated region Luciferase reporter assays), gene expression (quantitative PCR and microarray), cell migration and invasion, and cell growth were assessed under normoxic or hypoxic conditions, complemented by orthotopic xenograft of tumor cells to the mammary fat pad to investigate the effect of modulating miR-18a expression on primary tumor growth and lung metastasis. Last, clinically relevant correlations between miR-18a, HIF1A, hypoxia-responsive gene expression and distant metastasis–free survival (DMFS) were assessed using published expression array breast tumors data sets.

Results

miRNAs encoded by the MIR17HG gene were downregulated in lung metastases compared to primary tumors. Ectopic expression of miR-18a, a MIR17HG family member, in a metastatic variant of MDA-MB-231 cells reduced primary tumor growth and lung metastasis, whereas miR-18a inhibition in the parental cells promoted tumor growth and lung metastasis. We identified HIF1A as a direct target of miR-18a. Modulating miR-18a expression significantly affected hypoxic gene expression, cell invasiveness and sensitivity to anoikis and hypoxia in vitro in a HIF1A-dependent manner. Analysis of previously published data revealed that higher expression of HIF1A and a panel of hypoxic genes is associated with shorter DMFS interval in patients with basal-like breast tumors, and that, within this subtype, miR-18a expression is inversely correlated with hypoxic gene expression. Together, these data support a role of miR-18a in repressing distant metastasis through a HIF1A-dependent pathway.

Conclusions

The results of this study reveal a novel role for miR-18a in targeting HIF1A and repressing metastasis of basal-like breast tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/bcr3693) contains supplementary material, which is available to authorized users.

Identification and characterization of miR-92a and its targets modulating Vibrio splendidus challenged Apostichopus japonicus

miR-92a is a kind of disease related fine-tuning regulator which is not only related with tumorigenesis and tumor development but also participates in host-pathogen interaction in vertebrates. In present study, the potential targets of miR-92a in Apostichopus japonicus coelomocytes were screened by high-throughout sequencing and PCR approaches. Total of 10 annotated candidates were identified by hybrid PCR, and 23 were verified from RNA-seq, in which SMURF, PCBP and MEGF were found in both methods. The expression patterns of miR-92a and some putative targets were further characterized by qPCR at cell and individual levels. Vibrio splendidus and LPS exposure could significantly increase the expression level of sea cucumber miR-92a at all examined time points. Accordingly, strictly negative correlation expression profiles were detected in two candidates genes of MEGF and SMURF, suggesting that these two genes showed higher possibilities to be the targets of miR-92a in sea cucumber. Overall, the present work will enhance our understanding in the context of miR-92a modulating the interaction of sea cucumber upon pathogen challenged.

Identification of a circulating microRNA signature for colorectal cancer detection

Prognosis of patients with colorectal cancer (CRC) is generally poor because of the lack of simple, convenient, and noninvasive tools for CRC detection at the early stage. The discovery of microRNAs (miRNAs) and their different expression profiles among different kinds of diseases has opened a new avenue for tumor diagnosis. We built a serum microRNA expression profile signature and tested its specificity and sensitivity as a biomarker in the diagnosis of CRC. We also studied its possible role in monitoring the progression of CRC. We conducted a two phase case-control test to identify serum miRNAs as biomarkers for CRC diagnosis. Using quantitative reverse transcription polymerase chain reactions, we tested ten candidate miRNAs in a training set (30 CRCs vs 30 controls). Risk score analysis was used to evaluate the diagnostic value of the serum miRNA profiling system. Other independent samples, including 83 CRCs and 59 controls, were used to validate the diagnostic model. In the training set, six serum miRNAs (miR-21, let-7g, miR-31, miR-92a, miR-181b, and miR-203) had significantly different expression levels between the CRCs and healthy controls. Risk score analysis demonstrated that the six-miRNA-based biomarker signature had high sensitivity and specificity for distinguishing the CRC samples from cancer-free controls. The areas under the receiver operating characteristic (ROC) curve of the six-miRNA signature profiles were 0.900 and 0.923 for the two sets of serum samples, respectively. However, for the same serum samples, the areas under the ROC curve used by the tumor markers carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were only 0.649 and 0.598, respectively. The expression levels of the six serum miRNAs were also correlated with CRC progression. Thus, the identified six-miRNA signature can be used as a noninvasive biomarker for the diagnosis of CRC, with relatively high sensitivity and specificity.

Inhibition of microRNA miR-92a induces apoptosis and necrosis in human acute promyelocytic leukemia

BACKGROUND

MicroRNAs (miRNAs) are endogenous non-coding RNAs, 19-25 nucleotides in length, involved in post-transcriptional regulation of gene expression in a considerable majority of mRNAs. Different aspects of cellular activities like cell growth, proliferation, and differentiation are regulated by miRNAs through their regulatory effects on particular RNA species. In many tumors, up- or down-regulation of different miRNAs has been reported. In acute myeloid leukemia, up-regulation of miR-92a has been reported in human in-vitro studies.

MATERIALS AND METHODS

We performed inhibition of miR-92a in an acute promyelocytic leukemia cell line (HL-60), using locked nucleic acid (LNA) Antagomir. At different time points after LNA-anti-miR92a transfection, qRT-Real-Time-polymerase chain reaction (PCR) and Annexin-V/Propidium Iodide staining were performed and the data was analyzed using the Kruskal-Wallis and Mann-Whitney tests.

RESULTS

The assessment of the apoptosis and necrosis indicates that miR-92a inhibition can decrease the viable HL-60 cells and this is at least partially due to induction of apoptosis.

CONCLUSION

These findings suggest the inhibition of miR-92a as a novel approach for treatment of Acute Promyelocytic Leukemia (APL).

miR-92a family and their target genes in tumorigenesis and metastasis

The miR-92a family, including miR-25, miR-92a-1, miR-92a-2 and miR-363, arises from three different paralog clusters miR-17-92, miR-106a-363, and miR-106b-25 that are highly conservative in the process of evolution, and it was thought as a group of microRNAs (miRNAs) correlated with endothelial cells. Aberrant expression of miR-92a family was detected in multiple cancers, and the disturbance of miR-92a family was related with tumorigenesis and tumor development. In this review, the progress on the relationship between miR-92a family and their target genes and malignant tumors will be summarized.

MicroRNA-92a functions as an oncogene in colorectal cancer by targeting PTEN

BACKGROUND

Our previous studies show that microRNA-92a (miR-92a) is overexpressed in colorectal cancer (CRC) and is thought to be correlated with the development of the cancer. However, its biological role in CRC remains poorly understood.

AIMS

The aim of the study was to determine the role of miR-92a and to elucidate its regulatory mechanism in CRC.

METHODS

The expression levels of miR-92a and phosphatase and tensin homologue (PTEN) were detected by qRT-PCR and western blot. MTT, migration and invasion assays were used to examine the proliferation, migration and invasion of pre-miR-92a transfected SW480 cells, and a mouse model was used to investigate tumorigenesis. In addition, the regulation of PTEN by miR-92a was evaluated by qRT-PCR, western blot and luciferase reporter assays.

RESULTS

The expression of miR-92a was significantly up-regulated in the tissues of CRC patients with lymph node metastasis. The ectopic expression of miR-92a enhanced CRC cell proliferation, migration and invasion. Similar results were found in xenograft assay performed in nude mice. Up-regulation of miR-92a induced EMT in CRC cells. There was an inverse correlation between the levels of miR-92a and PTEN in CRC tissues. The overexpression of miR-92a in CRC cells decreased PTEN expression at the translational level, and decreased PTEN-driven luciferase-reporter activity.

CONCLUSIONS

Our results demonstrated that miR-92a induced EMT and regulated cell growth, migration and invasion in the SW480 cells, at least partially, via suppression of PTEN expression. MiR-92a may serve as a novel therapeutic target in colorectal cancer.

Stromal cells in tumor microenvironment and breast cancer

Cancer is a systemic disease encompassing multiple components of both tumor cells themselves and host stromal cells. It is now clear that stromal cells in the tumor microenvironment play an important role in cancer development. Molecular events through which reactive stromal cells affect cancer cells can be defined so that biomarkers and therapeutic targets can be identified. Cancer-associated fibroblasts (CAFs) make up the bulk of cancer stroma and affect the tumor microenvironment such that they promote cancer initiation, angiogenesis, invasion, and metastasis. In breast cancer, CAFs not only promote tumor progression but also induce therapeutic resistance. Accordingly, targeting CAFs provides a novel way to control tumors with therapeutic resistance. This review summarizes the current understandings of tumor stroma in breast cancer with a particular emphasis on the role of CAFs and the therapeutic implications of CAFs. In addition, the effects of other stromal components such as endothelial cells, macrophages, and adipocytes in breast cancer are also discussed. Finally, we describe the biologic markers to categorize patients into a specific and confirmed subtype for personalized treatment.

Identification of radiation-induced microRNA transcriptome by next-generation massively parallel sequencing

Gene regulation in cells exposed to ionizing radiation (IR) occurs at the transcriptional and post-transcriptional levels. Recent studies have suggested that micro-RNA (miRNA) play a significant role in post-transcriptional gene regulation in irradiated cells. miRNA are RNA molecules 18-24 nucleotides in length that are involved in negatively regulating the stability or translation of target messenger RNA. Previous studies from our laboratory have shown that the expression of various miRNA is altered in IR-treated cells. In the present study we monitored genome-wide expression changes of miRNA transcriptome by massively parallel sequencing of human cells irradiated with X-rays. The baseline expression of 402 miRNA indicated a wide range of modulation without exposure to IR. Differences in the expression of many miRNA were observed in a time-dependent fashion following radiation treatment. The Short Time-series Expression Miner (STEM) clustering tool was used to characterize 190 miRNA to six statistically significant temporal expression profiles. miR-19b and miR-93 were induced and miR-222, miR-92a, and miR-941 were repressed after radiation treatment. miR-142-3p, miR-142-5p, miR-107, miR-106b, miR-191, miR-21, miR-26a, miR-182, miR-16, miR-146a, miR-22 and miR-30e exhibited two peaks of induction: one at 8 h and the other at 24 h post-irradiation. miR-378, miR-let-7a, miR-let-7g, miR-let-7f, miR-103b, miR-486-3p, miR-423-5p, miR-4448, miR-3607-5p, miR-20b, miR-130b, miR-155, miR-181, miR-30d and miR-378c were induced only at the 8-h time-point. This catalogue of the inventory of miRNA that are modulated as a response to radiation exposure will be useful for explaining the mechanisms of gene regulation under conditions of stress.

Identification of circulating microRNA signatures for breast cancer detection

PURPOSE

There is a quest for novel noninvasive diagnostic markers for the detection of breast cancer. The goal of this study is to identify circulating microRNA (miRNA) signatures using a cohort of Asian Chinese patients with breast cancer, and to compare miRNA profiles between tumor and serum samples.

EXPERIMENTAL DESIGN

miRNA from paired breast cancer tumors, normal tissue, and serum samples derived from 32 patients were comprehensively profiled using microarrays or locked nucleic acid real-time PCR panels. Serum samples from healthy individuals (n = 22) were also used as normal controls. Significant serum miRNAs, identified by logistic regression, were validated in an independent set of serum samples from patients (n = 132) and healthy controls (n = 101).

RESULTS

The 20 most significant miRNAs differentially expressed in breast cancer tumors included miRNA (miR)-21, miR-10b, and miR-145, previously shown to be dysregulated in breast cancer. Only 7 miRNAs were overexpressed in both tumors and serum, suggesting that miRNAs may be released into the serum selectively. Interestingly, 16 of the 20 most significant miRNAs differentially expressed in serum samples were novel. MiR-1, miR-92a, miR-133a, and miR-133b were identified as the most important diagnostic markers, and were successfully validated; receiver operating characteristic curves derived from combinations of these miRNAs exhibited areas under the curves of 0.90 to 0.91.

CONCLUSION

The clinical use of miRNA signatures as a noninvasive diagnostic strategy is promising, but should be further validated for different subtypes of breast cancers.

Stromal cells in tumor microenvironment and breast cancer

Cancer is a systemic disease encompassing multiple components of both tumor cells themselves and host stromal cells. It is now clear that stromal cells in the tumor microenvironment play an important role in cancer development. Molecular events through which reactive stromal cells affect cancer cells can be defined so that biomarkers and therapeutic targets can be identified. Cancer-associated fibroblasts (CAFs) make up the bulk of cancer stroma and affect the tumor microenvironment such that they promote cancer initiation, angiogenesis, invasion, and metastasis. In breast cancer, CAFs not only promote tumor progression but also induce therapeutic resistance. Accordingly, targeting CAFs provides a novel way to control tumors with therapeutic resistance. This review summarizes the current understandings of tumor stroma in breast cancer with a particular emphasis on the role of CAFs and the therapeutic implications of CAFs. In addition, the effects of other stromal components such as endothelial cells, macrophages, and adipocytes in breast cancer are also discussed. Finally, we describe the biologic markers to categorize patients into a specific and confirmed subtype for personalized treatment.

Pathways to breast cancer recurrence

Breast cancer remains a deadly disease, even with all the recent technological advancements. Early intervention has made an impact, but an overwhelmingly large number of breast cancer patients still live under the fear of “recurrent” disease. Breast cancer recurrence is clinically a huge problem and one that is largely not well understood. Over the years, a number of factors have been studied with an overarching aim of being able to prognose recurrent disease. This paper attempts to provide an overview of our current knowledge of breast cancer recurrence and its associated challenges. Through a survey of the literature on cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), various signaling pathways such as Notch/Wnt/hedgehog, and microRNAs (miRNAs), we also examine the hypotheses that are currently under investigation for the prevention of breast cancer recurrence.

MiR-101 is involved in human breast carcinogenesis by targeting Stathmin1

Background

MicroRNA-101 (miR-101) expression is negatively associated with tumor growth and blood vessel formation in several solid epithelial cancers. However, the role of miR-101 in human breast cancer remains elusive.

Results

MiR-101 was significantly decreased in different subtypes of human breast cancer tissues compared with that in adjacent normal breast tissues (P<0.01). Up-regulation of miR-101 inhibited cell proliferation, migration and invasion, and promoted cell apoptosis in ER alpha-positive and ER alpha-negative breast cancer cells and normal breast cells. Down-regulation of miR-101 displayed opposite effects on cell growth and metastasis. Further investigation revealed a significant inverse correlation between the expression of miR-101 and Stathmin1 (Stmn1), and miR-101 could bind to the 3′-untranslated region (UTR) of Stmn1 to inhibit Stmn1 translation. The inhibition of cell growth and metastasis induced by up-regulation of miR-101 was partially restored by overexpresson of Stmn1. Knockdown of Stmn1 attenuates the down-regulation of miR-101-mediated enhancement of cell growth and metastasis. More importantly, in vivo analysis found that Stmn1 mRNA and protein level in different subtypes of human breast cancer tissues, contrary to the down-regulation of miR-101, were significantly elevated.

Conclusions

This study demonstrates that down-regulation of miR-101 in different subtypes of human breast cancer tissues is linked to the increase of cellular proliferation and invasiveness via targeting Stmn1, which highlights novel regulatory mechanism in breast cancer and may provide valuable clues for the future clinical diagnosis of breast cancer.