MicroRNAs expression in triple negative vs non triple negative breast cancer in Tunisia: interaction with clinical outcome

Dynamic Role of miRNAs in Salivary Gland Carcinomas: From Biomarkers to Therapeutic Targets

BACKGROUND

Salivary gland carcinomas (SGCs) are a rare group of malignant neoplasms of the head and neck region. MicroRNAs (miRNAs) are a class of small non-coding RNAs that have been associated with the control biological process and oncogenic mechanism by the regulation of gene expression at the post-transcriptional level. Recent evidence has suggested that miRNA expression may play a role in the tumorigenesis and carcinogenesis process in SGCs.

METHODS

This review provides a comprehensive literature review of the role of miRNAs expression in SGCs focusing on the diagnostic, prognostic, and therapeutic applications.

RESULTS

In this review, numerous dysregulated miRNAs have demonstrated an oncogenic and suppressor role in SGCs.

CONCLUSION

In the future, these miRNAs may eventually constitute useful diagnostic and prognostic biomarkers that may lead to a better understanding of SGCs oncogenesis. Additionally, the development of therapeutic agents based on miRNAs may be a promising target in SGC treatment.

22AG G-quadruplex RNA/QnMorpholine-mediated fluorimetric detection of miR-21

Herein we report a simple ligation/transcription-mediated system, using a 22AG G-quadruplex RNA secondary structure and a fluorescence-inducing QnMorpholine probe, for the detection of miR-21. In the presence of the target miR-21, two oligonucleotide probes (promoter and reporter) were ligated, thereby transcribing the 22AG RNA sequence, a complement of the reporter probe. In contrast, in the absence of this target-induced ligation, the reporter complement could not be transcribed to produce the 22AG RNA sequence. Subsequent addition of the QnMorpholine probe resulted in binding with the 22AG G-quadruplex RNA, thereby generating high fluorescence; no fluorescence occurred in the absence of this secondary structure. Hence, the presence of miR-21 was evidenced by a target-induced high-intensity signal. This simple one-pot fluorimetric system, which could detect miR-21 of up to 3.08 femtomolar in less than 30 min, holds promise as a diagnostic tool for selective and sensitive miRNA detection.

Investigation of BRCAness associated miRNA-gene axes in breast cancer: cell-free miR-182-5p as a potential expression signature of BRCAness

The concept of the ‘BRCAness’ phenotype implies the properties that some sporadic breast cancers (BC) share with BRCA1/2-mutation carriers with hereditary BC. Breast tumors with BRCAness have deficiencies in homologous recombination repair (HRR), like BRCA1/2-mutation carriers, and consequently could benefit from poly-(ADP)-ribose polymerase (PARP) inhibitors and DNA-damaging chemotherapy. Triple-negative breast cancers (TNBC) show a higher frequency of BRCAness than the other BC subtypes. Therefore, looking for BRCAness-related biomarkers could improve personalized management of TNBC patients. microRNAs (miRNAs) play a pivotal role in onco-transcriptomic profiles of tumor cells besides their suitable features as molecular biomarkers. The current study aims to evaluate the expression level of some critical miRNAs-mRNA axes in HRR pathway in tumors and plasma samples from BC patients. The expression levels of three multi-target miRNAs, including miR-182-5p, miR-146a-5p, and miR-498, as well as six downstream HRR-related protein-coding genes, have been investigated in the breast tumors and paired adjacent normal tissues by Real-time PCR. In the next step, based on the results derived from the previous step, we examined the level of cell-free miR-182-5p in the blood plasma samples from the patients. Our results highlight the difference between TNBC and non-TNBC tumor subgroups regarding the dysregulation of the key miRNA/mRNA axes involved in the HRR pathway. Also, for the first time, we show that the level of cell-free miR-182-5p in plasma samples from BC patients could be a clue for screening BC patients eligible for receiving PARP inhibitors through a personalized manner. Altogether, some sporadic BC patients, especially sporadic TNBC, have epigenetically dysregulated HRR pathway that could be identified and benefit from BRCAness-specific therapeutic agents.

Circulating microRNA biomarkers in melanoma and non-melanoma skin cancer

INTRODUCTION

Skin cancer is the most common type of cancer and is classified in melanoma and non-melanoma cancers, which include basal cell, squamous cell and Merkel cell carcinoma. Specific microRNAs are dysregulated in each skin cancer type. MicroRNAs act as oncogene or tumor suppressor gene regulators and are actively released from tumor cells in the circulation. Cell-free microRNAs serve many, and possibly yet unexplored, functional roles, but their presence and abundance in the blood has been investigated as disease biomarker. Indeed, specific microRNAs can be isolated and quantified in the blood, usually in serum or plasma fractions, where they are uncommonly stable. MicroRNA levels reflect underlying conditions and have been associated with skin cancer presence, stage, evolution, or therapy efficacy.

AREAS COVERED

In this review, we summarize the state of the art on circulating microRNAs detectable in skin cancer patients including all the studies that performed microRNA identification and quantification in the circulation using appropriate sample size and statistics and providing detailed methodology, with a specific focus on diagnostic and prognostic biomarkers.

EXPERT OPINION

Circulating microRNAs display a relevant biomarker potential. We expect the development of methodological guidelines and standardized protocols for circulating miRNA quantification in clinical settings.

Rapid and ultrasensitive detection of DNA and microRNA-21 using a zirconium porphyrin metal-organic framework-based switch fluorescence biosensor

Sensitive and accurate detection of nucleic acid biomarkers is critical for early cancer diagnosis, disease monitoring, and clinical treatment. In this study, we developed a switch fluorescence biosensor for simple and high-efficient detection of nucleic acid biomarkers using 6-carboxyfluorescein (FAM)-modified single-stranded DNA (ssDNA) probes (FAM-P1/P2), and zirconium porphyrin metal-organic framework nanoparticles (ZrMOF) acted as fluorescence quencher. FAM-P1/P2 probes were adsorbed on ZrMOF surface because of π-π stacking, hydrogen bonding, and electrostatic interactions. Fluorescence quenching event occurred by fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET) processes, thereby achieving the "off" fluorescence status. Once the specific binding was formed between the fluorescence probes and the targets, the rigid double-stranded DNA (dsDNA) structures were released from ZrMOF surface, resulting in the recovery of fluorescence and the "on" status. Because of the superior adsorption ability of ZrMOF toward ssDNA than dsDNA, the switch of fluorescence signals from "off" to "on" allowed rapid and ultrasensitive detection of ssDNA (T1) and microRNA-21 (miR-21) within 30 min. The limit of detection (signal-to-noise ratio = 3) for T1 and miR-21 were 2 fM and 11 aM, respectively. Moreover, the proposed strategy was very simple as it worked by the facile adsorption-quenching-recovery mechanism without difficult and complicated immobilization processes. Also, this biosensor showed an excellent analytical performance in the detection of miR-21 in human serum samples. Therefore, this biosensor might be considered a potential tool for the detection of DNA and miRNA biomarkers in clinical samples.

In vivo and in vitro impact of miRNA-153 on the suppression of cell growth apoptosis through mTORC2 signaling pathway in breast cancer

PURPOSE

To investigate the effects and mechanism of miRNA-153 on breast cancer cells in vitro and in vivo.

MATERIAL AND METHODS

The cells and mice were divided into five groups: miRNA-153 mimic, miRNA-153 NC, miRNA-153 inhibitor, miRNA-153 inhibitor-NC, and blank control groups. The real-time PCR and western blot were used to detect the rictor expression regulated by miRNA-153. The western blot was used to explore the expression levels of p-Akt Ser473, p-SGK1 Ser422, and p-FOXO1 Thr24 regulated by miRNA-153. The H&E stain was used to detect the morphology and vitality of tumor cells. Flow cytometry analysis or TUNEL detection was used to evaluate the apoptosis of tumor cells.

RESULTS

MiRNA-153 was significantly reduced in breast cancer cell lines. The real-time PCR and western blot assay suggested that the miRNA-153 downregulation of rictor expression, which was correlated with the antitumor effects both in vitro and in vivo. The western blot assay also showed that the expression levels of p-Akt Ser473, p-SGK1 Ser422, and p-FOXO1 Thr24 were largely reduced in miRNA-153 treated group, which indicated that miRNA-153 inhibited breast cancer growth by regulation of mTORC2 signaling pathway. The H&E stain demonstrated that the morphology and vitality of tumor cells in tumor tissues were influenced in miRNA-153 mimic treated group. The TUNEL detection also showed a great quantity of apoptotic cells in the miRNA-153 mimic group.

CONCLUSIONS

All these results uncovering that the miRNA-153 inhibited breast cancer growth via regulation of mTORC2 signaling pathway, which provided breast cancer treatment a novel direction.

Triple negative breast cancer in the era of miRNA

The objective of this review is to elucidate the role of miRNAs in triple negative breast cancer (TNBC). To achieve our goal, we searched databases such as PubMed, ScienceDirect, Springer, Web of Science and Scopus. We retrieved up to 1233 articles, based a rigorous selection criterion, only 197 articles were extensively reviewed. We selected articles only addressing TNBC, but not other types of breast cancer, with the employed approach being miRNA analysis and/or profiling. Our extensive review resulted in grouping of miRNAs into categories in which specific members of miRNAs have roles in specific mechanism in TNBC i.e., carcinogenesis, invasion, metastasis, apoptosis, diagnosis, prognosis, and treatment. TNBC is an aggressive subtype of breast cancer; therefore, different approaches for accurate diagnosis, prognosis and treatment are needed. In this review we summarize the up-to-date miRNA profiling, prognostic, and therapeutic findings that add to the route of controlling TNBC.

Prognostic role of microRNA 182 and microRNA 18a in locally advanced triple negative breast cancer

Background

The study assessed the epigenetic regulation and the role of microRNA (miR) expression in locally advanced triple negative breast cancers (TNBC) and comparison with the clinico-pathological variables and survival.

Methods

Fifty patients of locally advanced TNBC during the period 2011–2013 were included. Expression level of test microRNA (miR-182 and miR-18a) was determined using Taqman quantitative Real time polymerase chain reaction (qRT-PCR) from formalin fixed paraffin embedded biopsy blocks. Clinical and demographic information and survival data was retrieved from the Hospital medical records.

Results

An improved clinical complete response (cCR) was observed in patients with age ≥ 45 years (80%), premenopausal status (70%), tumor size < 6 cms (80%), nodal status N0-N1 (95%) and grade II-III tumor (80%). A statistically significant correlation was observed on comparison of cCR with menopausal status (p-value 0.020), T category (p-value 0.018) and the clinical nodal status (p-value 0.003). pCR also correlated with clinical nodal status (p-value 0.008). Epigenetically, miR-18a under expression (< 8.84) was most commonly associated with tumor size < 6 cms (76.7%), clinical nodal status N0-N1 (90%), cCR (60%) and pCR (53.3%). A similar trend was observed with miR-182. Statistical significance was observed with T category (p-values 0.003 and 0.004), clinical nodal status (p-values 0.001 and 0.001), clinical response (p-values 0.002 and 0.002) and pathological response (p-values 0.007 and 0.006) with respect to miR-18a and miR-182, respectively. Also, the menopausal status significantly correlated with the miR-182 expression (p-value 0.009). miR-182 overexpression (≥ 6.32) was not observed in any of the postmenopausal patients. A univariate cox proportional hazard regression model also showed statistical interactions (p-values <0.004).

Conclusion

miR-182 and miR-18a overexpression correlates with worse clinical and pathological tumor characteristics in locally advanced TNBC and hence could be used to predict the outcomes and prognosis in these patients.

Uncovering the expression patterns and the clinical significance of miR-182, miR-205, miR-27a and miR-369 in patients with urinary bladder cancer

BACKGROUND

Given the high recurrence and progression rates and the absence of reliable markers for early detection and prognosis prediction of patients with urothelial bladder cancer (BCa), the exploration of new biomarkers with high specificity is imperative. Mainly, microRNAs (miRNAs), which are involved in the initiation and the progression of BCa. Herein, the expression patterns of miR-182, miR-205, miR-27a and miR-369 were evaluated in patients with urothelial BCa.

METHODS AND RESULTS

The expression levels of the miRNAs were investigated in 90 FFPE tissue samples (23 LG NMIBC, 44 HG NMIBC, 23 MIBC) and 10 non tumoral bladder tissues using TaqMan based RT-qPCR. Data analysis was performed using 2^-ΔΔCT method. Correlation to clinical characteristics of the patients was performed using descriptive statistics and the receiver operating characteristic (ROC) curve was performed to evaluate the diagnostic value of all miRNAs. MiR-27a, miR-205 and miR-369 were down-regulated whereas miR-182 was up-regulated in patients compared to controls (p < 0.001). MiR-205 and miR-182 positively segregate between NMIBC and MIBC (p = 0.002 and p = 0.000 respectively) whereas the distribution of miR-27a's expression among these tumor groups was almost significant (p = 0.05) and that of miR-369's expression was irrelevant (p = 0.618). Interestingly, miR-182 was discriminative between LG NMIBC and HG NMIBC (p < 0.001) and Ta/T1 tumors (p = 0.000). Furthermore, high levels of miR-182 were potentially predictive of progression in NMIBC patients (p = 0.01).

CONCLUSION

Collectively, a selection of miRNAs was found to be aberrantly expressed in BCa suggesting a potential diagnostic value in BCa. In addition, the clinical value of miR-182 and miR-205 as potential prognosis biomarkers was highlighted. Indeed, our data provide additional insights into cancer biology. Further functional or target studies are mandatory to strengthen these findings.

The Promising Role of miR-21 as a Cancer Biomarker and Its Importance in RNA-Based Therapeutics

MicroRNAs are small noncoding transcripts that posttranscriptionally regulate gene expression via base-pairing complementarity. Their role in cancer can be related to tumor suppression or oncogenic function. Moreover, they have been linked to processes recognized as hallmarks of cancer, such as apoptosis, invasion, metastasis, and proliferation. Particularly, one of the first oncomiRs found upregulated in a variety of cancers, such as gliomas, breast cancer, and colorectal cancer, was microRNA-21 (miR-21). Some of its target genes associated with cancer are PTEN (phosphatase and tensin homolog), PDCD4 (programmed cell death protein 4), RECK (reversion-inducing cysteine-rich protein with Kazal motifs), and STAT3 (signal transducer activator of transcription 3). As a result, miR-21 has been proposed as a plausible diagnostic and prognostic biomarker, as well as a therapeutic target for several types of cancer. Currently, research and clinical trials to inhibit miR-21 through anti-miR-21 oligonucleotides and ADM-21 are being conducted. As all of the evidence suggests, miR-21 is involved in carcinogenic processes; therefore, inhibiting it could have effects on more than one type of cancer. However, whether miR-21 can be used as a tissue-specific biomarker should be analyzed with caution. Consequently, the purpose of this review is to outline the available information and recent advances regarding miR-21 as a potential biomarker in the clinical setting and as a therapeutic target in cancer to highlight its importance in the era of precision medicine.

Prognostic role of microRNAs in breast cancer: A systematic review

MicroRNAs (miRNAs) have been found to play an important role in breast cancer, functioning either as potential oncogenes or tumor suppressor genes, but their role in the prognosis of patients remains unclear. The aim of the present review study is to highlight recent preclinical and clinical studies performed on both circulating and tissue-specific miRNAs and their potential role as prognostic markers in breast cancer. We systematically searched the PubMed database to explore the prognostic value of miRNAs in breast cancer. After performing the literature search and review, 117 eligible studies were identified. We found that 110 aberrantly expressed miRNAs have been associated with prognosis in breast cancer. In conclusion, the collective data presented in this review indicate that miRNAs could serve as novel prognostic tools in breast cancer, while the clinical application of these findings has yet to be verified.

MicroRNAs Involved in Carcinogenesis, Prognosis, Therapeutic Resistance and Applications in Human Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive, prevalent, and distinct subtype of breast cancer characterized by high recurrence rates and poor clinical prognosis, devoid of both predictive markers and potential therapeutic targets. MicroRNAs (miRNA/miR) are a family of small, endogenous, non-coding, single-stranded regulatory RNAs that bind to the 3′-untranslated region (3′-UTR) complementary sequences and downregulate the translation of target mRNAs as post-transcriptional regulators. Dysregulation miRNAs are involved in broad spectrum cellular processes of TNBC, exerting their function as oncogenes or tumor suppressors depending on their cellular target involved in tumor initiation, promotion, malignant conversion, and metastasis. In this review, we emphasize on masses of miRNAs that act as oncogenes or tumor suppressors involved in epithelial–mesenchymal transition (EMT), maintenance of stemness, tumor invasion and metastasis, cell proliferation, and apoptosis. We also discuss miRNAs as the targets or as the regulators of dysregulation epigenetic modulation in the carcinogenesis process of TNBC. Furthermore, we show that miRNAs used as potential classification, prognostic, chemotherapy and radiotherapy resistance markers in TNBC. Finally, we present the perspective on miRNA therapeutics with mimics or antagonists, and focus on the challenges of miRNA therapy. This study offers an insight into the role of miRNA in pathology progression of TNBC.

Expression and polymorphism of micro-RNA according to body mass index and breast cancer presentation in Tunisian patients

Micro-RNAs (miRs) constitute a class of small noncoding RNAs implicated in the regulation of gene expression by binding to target mRNAs. A miR can target several mRNAs, being involved in different biologic processes and pathologies. This pleiotropic function might explain the link between diseases co-occurrence. Epigenetic origin of the link between obesity and breast cancer (BC) is investigated in a cohort of Tunisian patients, focusing on polymorphism at germline level (miR-146a) and on expression in mammary tumors (miR-21, miR-146a, and miR-34a), according to body mass index (BMI) and clinico-pathologic features. The measure of miR expression in 60 mammary tumors was realized using quantitative RT-PCR. Study of rs 2910164 in miR-146a was performed by PCR and direct sequencing using blood DNA of 83 affected women and 50 unrelated subjects from Great Tunis. MiR-21, miR-146a, and miR-34a have been quantified in breast tumor according to BMI. MiR-21 is significantly more expressed in tumors of obese women comparatively to nonobese patients. On the contrary, miR-34a is decreased in tumors of obese women. Moreover, in obese BC patients, a significant increase in both miR-21 and miR-146a expression is revealed in cases with lymph node metastasis. The polymorphism at rs 2910164 (miR-146a) locus was not shown as a risk factor for BC. However the mutant CC genotype was revealed to be associated with a risk for bad outcome of the disease. Chronic inflammation in obese women would be linked to aggressive breast tumors via induction of oncomiRs overexpression and decrease of tumor suppressor miRs.

OncomiR-10b hijacks the small molecule inhibitor linifanib in human cancers

The pervasive role of microRNAs (miRNAs) in cancer pathobiology drives the introduction of new drug development approaches such as miRNA inhibition. In order to advance miRNA-therapeutics, meticulous screening strategies addressing specific tumor targets are needed. Small molecule inhibitors represent an attractive goal for these strategies. In this study, we devised a strategy to screen for small molecule inhibitors that specifically inhibit, directly or indirectly, miR-10b (SMIRs) which is overexpressed in metastatic tumors. We found that the multi-tyrosine kinase inhibitor linifanib could significantly inhibit miR-10b and reverse its oncogenic function in breast cancer and liver cancer both in vitro and in vivo. In addition, we showed that the efficacy of linifanib to inhibit tyrosine kinases was reduced by high miR-10b levels. When the level of miR-10b is high, it can “hijack” the linifanib and reduce its kinase inhibitory effects in cancer resulting in reduced anti-tumor efficacy. In conclusion, our study describes an effective strategy to screen for small molecule inhibitors of miRNAs. We further propose that miR-10b expression levels, due to the newly described “hijacking” effect, may be used as a biomarker to select patients for linifanib treatment.

MicroRNAs in regulation of triple-negative breast cancer progression

PURPOSE

Dysregulation of miRNA profile has been associated with a broad spectrum of cellular processes underlying progression of various human malignancies. Increasing evidence suggests that specific microRNA clusters might be of clinical utility, especially in triple-negative breast carcinoma (TNBC), devoid of both predictive markers and potential therapeutic targets. Here we provide a comprehensive review of the existing data on microRNAs in TNBC, their molecular targets, a putative role in invasive progression with a particular emphasis on the epithelial-to-mesenchymal transition (EMT) and acquisition of stem-cell properties (CSC), regarded both as prerequisites for metastasis, and significance for therapy.

METHODS

PubMed and Medline databases were systematically searched for the relevant literature. 121 articles have been selected and thoroughly analysed.

RESULTS

Several miRNAs associated with EMT/CSC and invasion were identified as significantly (1) upregulated: miR-10b, miR-21, miR-29, miR-9, miR-221/222, miR-373 or (2) downregulated: miR-145, miR-199a-5p, miR-200 family, miR-203, miR-205 in TNBC. Dysregulation of miR-10b, miR-21, miR-29, miR-145, miR-200 family, miR-203, miR-221/222 was reported of prognostic value in TNBC patients.

CONCLUSION

Available data suggest that specific microRNA clusters might play an important role in biology of TNBC, understanding of which should assist disease prognostication and therapy.

Levels of MicroRNA Heterogeneity in Cancer Biology

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression, involved in the silencing of messenger RNA (mRNA) translation. The importance of miRNA signatures in disease screening, prognosis, and progression of different tumor types and subtypes is increasing. miRNA expression levels change depending on numerous factors. In this review, we are describing the circumstances under which miRNA levels can change, these are named 'levels' of heterogeneity of miRNAs. miRNAs can have oncogenic, tumor suppressive, or both roles depending on tumor type and target mRNA whose translation they silence. The expression levels of a single miRNA may vary across different cancer types and subtypes, indicating that a miRNA signature may be tissue specific. miRNA levels of expression also vary during disease formation and propagation, indicating the presence of a time profile for their expression. The complexity of the miRNA-mRNA interference network mirrors different genetic and epigenetic changes that influence miRNA and mRNA availability to each other, and hence, their binding ability. The potential role of miRNAs as biomarkers is two-fold; first, for monitoring of the phases of cancer pathogenesis, and second, to characterize the particular type/subtype of cancer. It is important that a particular miRNA should be characterized by examining as many types and subtypes of cancers as are available, as well as being extracted from different types of samples, in order to obtain a complete picture of its behavior and importance in the disease pathology.

Dysregulation and functional roles of miR-183-96-182 cluster in cancer cell proliferation, invasion and metastasis

Previous studies have reported aberrant expression of the miR-183-96-182 cluster in a variety of tumors, which indicates its' diagnostic or prognostic value. However, a key characteristic of the miR-183-96-182 cluster is its varied expression levels, and pleomorphic functional roles in different tumors or under different conditions. In most tumor types, the cluster is highly expressed and promotes tumorigenesis, cancer progression and metastasis; yet tumor suppressive effects have also been reported in some tumors. In the present study, we discuss the upstream regulators and the downstream target genes of miR-183-96-182 cluster, and highlight the dysregulation and functional roles of this cluster in various tumor cells. Newer insights summarized in this review will help readers understand the different facets of the miR-183-96-182 cluster in cancer development and progression.

The diagnostic role of microRNA-34a in breast cancer: a systematic review and meta-analysis

BACKGROUND

MicroRNA-34a (miR-34a) is a master regulator of tumor suppression in breast cancer (BC). This systematic review aims to analyze the diagnostic accuracy of miR-34a in the detection of BC as a biomarker.

RESULTS

A total of 1858 BC cases and 494 controls from thirteen eligible studies reported in 9 publications were included. The overall pooled sensitivity, specificity, negative likelihood ratio (NLR), positive likelihood ratio (PLR), and diagnostic odds ratio (DOR) were 85.50% (95% CI: 83.80-87.00%), 70.00% (95% CI: 65.80-74.10%), 0.29 (95% CI: 0.19-0.43), 2.58 (95% CI: 1.91-3.43), and 9.39 (95% CI: 5.47-16.12), respectively. Similarly, the overall area under the curve (AUC) of the summary receiver operating characteristic (SROC) was 0.80, indicating the high conservation of miR-34a as a biomarker. Furthermore, subgroup analysis suggested that the use of miR-34a as a biomarker is more accurate in tissue-based sample of invasive BC. We also indicated that miR-34a is a capable biomarker in diagnosing BC in people of Caucasian descent.

MATERIALS AND METHODS

A systematic search was conducted for eligible publications that address miR-34a expression level in BC cases and noncancerous controls. Diagnostic capacity of miR-34a for BC was assessed using pooled sensitivity and specificity, DOR, and AUC of SROC. PLR and NLR were verified to estimate the miR-34a diagnostic accuracy in clinical level. The quality of the included studies was assessed by QUADAS-2.

CONCLUSIONS

These findings suggest miR-34a is a promising non-invasive biomarker in diagnosing BC. Well-designed cohort studies should be implemented to warrant the diagnostic value of miR-34a in clinical purposes.

MicroRNA-182 promotes proliferation and metastasis by targeting FOXF2 in triple-negative breast cancer

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer (BC), is characterized as high proliferation, young age and poor prognosis. MicroRNA-182 (miR-182) was reported to have oncogenic potential in many cancers. We aimed to elucidate pathobiological effects of miR-182 expression by targeting forkhead-box F2 (FOXF2) in TNBC. In this study, we explored the functional role of miR-182 expression in TNBC. Quantitative real-time PCR (qRT-PCR) was applied to evaluate the expression of miR-182 in cell lines and tissues. A series of in vitro and in vivo assays were performed in the MCF-7 and MDA-MB-231 cell lines with miR-182 overexpression. Luciferase reporter assays and western blot analysis were used to identify FOXF2 as the direct and functional target of miR-182. In TNBC tissues and cell lines, we found that miR-182 was significantly upregulated. Transwell assay showed that re-expression of miR-182 increased cell migration and invasion abilities and MTT assay showed that it promoted cell growth in vitro. In vivo assay, re-expression of miR-182 significantly increase tumor volume and enhanced instant metastasis in the lungs of mice. Besides, FOXF2 was identified as a direct and functional target of miR-182. These results indicated that miR-182 plays an important role in the initiation and progression of TNBC by targeting FOXF2 and the miR-182/FOXF2 axis may present a new therapeutic strategy for TNBC in the future.

MicroRNAs in the development and neoplasia of the mammary gland

Study on the role of microRNAs (miRs) as regulators of gene expression through posttranscriptional gene silencing is currently gaining much interest,due to their wide involvement in different physiological processes. Understanding mammary gland development, lactation, and neoplasia in relation to miRs is essential. miR expression profiling of the mammary gland from different species in various developmental stages shows their role as critical regulators of development. miRs such as miR-126, miR-150, and miR-145 have been shown to be involved in lipid metabolism during lactation. In addition, lactogenic hormones influence miR expression as evidenced by overexpression of miR-148a in cow mammary epithelial cells, leading to enhanced lactation. Similarly, the miR-29 family modulates lactation-related gene expression by regulating DNA methylation of their promoters. Besides their role in development, lactation and involution, miRs are responsible for breast cancer development. Perturbed estrogen (E2) signaling is one of the major causes of breast cancer. Increased E2 levels cause altered expression of ERα, and ERα-miR cross-talk promotes tumour progression. miRs, such as miR-206, miR-34a, miR-17-5p, and miR-125 a/b are found to be tumour suppressors; whereas miR-21, miR-10B, and miR-155 are oncogenes. Oncogenic miRs like miR-21, miR-221, and miR-210 are overexpressed in triple negative breast cancer cases which can be diagnostic biomarker for this subtype of cancer.  This review focuses on the recent findings concerning the role of miRs in developmental stages of the mammary gland (mainly lactation and involution stages) and their involvement in breast cancer progression. Further studies in this area will help us to understand the molecular details of mammary gland biology, as well as miRs that could be therapeutic targets of breast cancer.

Critical role of HMGA proteins in cancer cell chemoresistance

The high-mobility group A (HMGA) proteins are frequently overexpressed in human malignancies and correlate with the presence of metastases and reduced patient survival. Here, we highlight the main studies evidencing a critical role of HMGA in chemoresistance, mainly by activating Akt signaling, impairing p53 activity, and regulating the expression of microRNAs that target genes involved in the susceptibility of cancer cells to antineoplastic agents. Therefore, these studies account for the association of HMGA overexpression with patient poor outcome, indicating the impairment of HMGA as a fascinating perspective for effectively improving cancer therapy.

Identification of Specific miRNA Signature in Paired Sera and Tissue Samples of Indian Women with Triple Negative Breast Cancer

Of several subtypes of breast cancer, triple negative breast cancer (TNBC) is a highly aggressive tumor that lacks expression of hormone receptors for estrogen, progesterone and human epidermal growth factor receptor 2 and shows a worst prognosis. The small noncoding RNAs (miRNAs) considered as master regulator of gene expression play a key role in cancer initiation, progression and drug resistance and have emerged as attractive molecular biomarkers for diagnosis, prognosis and treatment targets in cancer. We have done expression profiling of selected miRNAs in paired serum and tissue samples of TNBC patients and corresponding cell lines and compared with that of other subtypes, in order to identify novel serum miRNA biomarkers for early detection and progression of TNBC. A total of 85 paired tumor tissues and sera with an equal number of adjacent normal tissue margins and normal sera from age matched healthy women including tissue and sera samples from 15 benign fibroadenomas were employed for the study. We report for the first time an extremely high prevalence (73.9%) of TNBC in premenopausal women below 35 years of age and a significant altered expression of a panel of three specific oncogenic miRNAs- miR-21, miR-221, miR-210, and three tumor suppressor miRNAs- miR-195, miR-145 and Let-7a in both tissues and corresponding sera of TNBC patients when compared with triple positive breast cancer (TPBC) patients. While miR-21, miR-221 and miR-210 showed significant over-expression, miR-195 and miR-145 were downregulated and well correlated with various clinicopathological and demographic risk factors, tumor grade, clinical stage and hormone receptor status. Interestingly, despite being a known tumor suppressor, Let-7a showed a significant overexpression in TNBCs. It is suggested that this panel of six miRNA signature may serve as a minimally invasive biomarker for an early detection of TNBC patients.

Phosphorylated mTOR is associated to androgen receptor expression in early triple-negative breast cancer

The significance of phosphorylated mTOR (p-mTOR) expression is unknown in triple-negative breast carcinoma (TNBC). The aims of the present study were to assess the expression of p-mTOR in early TNBC and to evaluate possible correlations between androgen receptor (AR) expression, clinicopathological parameters and disease outcome. Between January 2009 and December 2013, all consecutive patients who were diagnosed and completed the treatment of invasive TNBC at our institution were eligible for this analysis. Patients with stage IV disease were excluded. The evaluation of p-mTOR immunohistochemical staining was semi-quantitatively considering both the percentage of positive tumor cells (range, 0-100%) and staining intensity (range, 0-3+). Ninety-eight TNBC patients were included. Approximately 33% of cases were p-mTOR positive and there was no association between positive immunostaining for p-mTOR and DFS (p=0.74) and OS (p=0.81). p-mTOR positivity was associated with small tumor size (p=0.03) and AR expression (p=0.04). High expression of p-mTOR may drive tumor proliferation in almost one third of TNBC. The biological association between mTOR activation and AR pathway suggests that there may exist a subgroup of TNBC in which the combination of both AR antagonism and mTOR inhibition should have a synergistic effect on cell growth and tumor progression.

Thioaptamer-conjugated CD44-targeted delivery system for the treatment of breast cancer in vitro and in vivo

The high transfection efficiency and enhanced therapeutic effect of drug delivery systems developed in recent years imply that ligand-decorated nanocarriers are potentially targeted vectors for breast cancer treatment. Thioaptamer (TA)-modified nanoparticles (NPs) designed in this study mainly consisted of ligand TA and dendritic polyamidoamine (PAMAM). Knowing that TA can bind to CD44-receptors in breast cancer, this study was intended to validate the safety and feasibility of systemic miRNA delivery to breast cancer cells by TA-PEG-PAMAM/miRNA (polyethylene glycol - PEG), testify its tumor targeting efficiency in vitro, and observe its biodistribution when it was administered systemically to a xenograft mouse model of breast cancer. The in vivo and ex vivo imaging results in human breast cancer tumor-bearing mice showed that TA-modification was able to enhance the accumulation of NPs in the breast cancer tumor. Our data showed that TA-NPs did not induce functional impairment to normal tissues and vital organs. TA-NPs may prove to be a safe and effective miRNA deliver system for breast cancer treatment, and could be widely used in pre-clinical and eventually clinical arenas of breast cancer treatment.

Prognostic Value of MicroRNA-182 in Cancers: A Meta-Analysis

OBJECTIVE

MicroRNA-182 (miR-182) exhibits altered expression in various cancers. The aim of this study was to investigate the predictive value of miR-182 expression for cancer patient survival.

METHODS

Eligible studies were identified through multiple search strategies, and the hazard ratios (HRs) for patient outcomes were extracted and estimated. A meta-analysis was performed to evaluate the prognostic value of miR-182.

RESULTS

In total, 14 studies were included. A high miR-182 expression level predicted a worse outcome with a pooled HR of 2.18 (95% CI: 1.53-3.11) in ten studies related to overall survival (OS), especially in Chinese populations. The results of seven studies evaluating disease-free survival/relapse-free survival/recurrence-free interval/disease-specific survival (DFS/RFS/RFI/DSS) produced a pooled HR of 1.77 (95% CI: 0.91-3.43), which was not statistically significant; however, the trend was positive. When disregarding the DSS from one study, the expression of miR-182 was significantly correlated with DFS/RFS/RFI (pooled HR = 2.52, 95% CI: 1.67-3.79).

CONCLUSIONS

High miR-182 expression is associated with poor OS and DFS/RFS/RFI in some types of cancers, and miR-182 may be a useful prognostic biomarker for predicting cancer prognosis. However, given the current insufficient relevant data, further clinical studies are needed.