Impact of tumour epithelial subtype on circulating microRNAs in breast cancer patients

In situ measurement of miR-138 expression in oral squamous cell carcinoma tissue supports the role of this microRNA as a tumor suppressor

BACKGROUND

Oral squamous cell carcinoma is the eighth most common cancer worldwide with a relatively high rate of metastasis (~40%). Previously, we showed that microRNA-138 serves as a functional tumor suppressor and plays an important role in oral squamous cell carcinoma metastasis. However, to date, microRNA-138 expression has not been examined in this tumor tissue. Herein, we demonstrated that microRNA-138 expression is downregulated in metastatic oral squamous cell carcinoma specimens using tissue microarray technology with in situ hybridization.

METHODS

The study included 254 oral squamous cell carcinoma patients from two centers (160 from the Chengdu center and 90 from the Guangzhou center) and four healthy volunteers.

RESULTS

Multivariate analysis showed that microRNA-138 expression was independent of tumor stage, age, gender, smoking, and alcohol consumption in oral squamous cell carcinoma patients. Interestingly, patients that expressed lower levels of microRNA-138 (determined by in situ hybridization) were more prone to regional lymph node metastasis and exhibited poorer outcomes. These findings support the role of microRNA-138 as a tumor suppressor in oral squamous cell carcinoma.

CONCLUSION

In summary, the expression level of microRNA-138 is negatively correlated with oral squamous cell carcinoma metastasis; the lower the expression of microRNA-138, the higher the rate of metastasis and the poorer the prognosis of the patients. Therefore, our study confirms that microRNA-138 serves as a tumor suppressor and plays a functional role in oral squamous cell carcinoma tumor metastasis; microRNA-138 constitutes a promising prognosis biomarker and therapeutic target for oral squamous cell carcinoma with metastasis potential.

HNRNPA2/B1 is upregulated in endocrine-resistant LCC9 breast cancer cells and alters the miRNA transcriptome when overexpressed in MCF-7 cells

MicroRNAs are dysregulated in breast cancer. Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2/B1) is a reader of the N(6)-methyladenosine (m6A) mark in primary-miRNAs (pri-miRNAs) and promotes DROSHA processing to precursor-miRNAs (pre-miRNAs). We examined the expression of writers, readers, and erasers of m6A and report that HNRNPA2/B1 expression is higher in tamoxifen-resistant LCC9 breast cancer cells as compared to parental, tamoxifen-sensitive MCF-7 cells. To examine how increased expression of HNRNPA2/B1 affects miRNA expression, HNRNPA2/B1 was transiently overexpressed (~5.4-fold) in MCF-7 cells for whole genome miRNA profiling (miRNA-seq). 148 and 88 miRNAs were up- and down-regulated, respectively, 48 h after transfection and 177 and 172 up- and down-regulated, respectively, 72 h after transfection. MetaCore Enrichment analysis identified progesterone receptor action and transforming growth factor β (TGFβ) signaling via miRNA in breast cancer as pathways downstream of the upregulated miRNAs and TGFβ signaling via SMADs and Notch signaling as pathways of the downregulated miRNAs. GO biological processes for mRNA targets of HNRNPA2/B1-regulated miRNAs included response to estradiol and cell-substrate adhesion. qPCR confirmed HNRNPA2B1 downregulation of miR-29a-3p, miR-29b-3p, and miR-222 and upregulation of miR-1266-5p, miR-1268a, miR-671-3p. Transient overexpression of HNRNPA2/B1 reduced MCF-7 sensitivity to 4-hydroxytamoxifen and fulvestrant, suggesting a role for HNRNPA2/B1 in endocrine-resistance.

Age-related microRNAs in older breast cancer patients: biomarker potential and evolution during adjuvant chemotherapy

Background

MicroRNAs (miRNAs) are important regulators of cellular function and have been associated with both aging and cancer, but the impact of chemotherapy on age-related miRNAs has barely been studied.

Our aim was to examine whether chemotherapy accelerates the aging process in elderly breast cancer patients using miRNA expression profiling.

Methods

We monitored age-related miRNAs in blood of women, aged 70 or older, receiving adjuvant chemotherapy (docetaxel and cyclophosphamide, TC) for invasive breast cancer (chemo group, CTG, n = 46). A control group of older breast cancer patients without chemotherapy was included for comparison (control group, CG, n = 43). All patients underwent geriatric assessment at inclusion (T0), after 3 months (T1) and 1 year (T2). Moreover, we analysed the serum expression of nine age-related miRNAs (miR-20a, miR-30b, miR-34a, miR-106b, miR-191, miR-301a, miR-320b, miR-374a, miR-378a) at each timepoint.

Results

Except for miR-106b, which behaved slightly different in CTG compared to CG, all miRNAs showed moderate fluctuations during the study course with no significant differences between groups. Several age-related miRNAs correlated with clinical frailty (miR-106b, miR-191, miR-301a, miR-320b, miR-374a), as well as with other biomarkers of aging, particularly Interleukin-6 (IL-6) and Monocyte Chemoattractant Protein-1 (MCP-1) (miR-106b, miR-301a, miR-374a-5p, miR-378a-3p). Moreover, based on their ‘aging miRNA’ profiles, patients clustered into two distinct groups exhibiting significantly different results for several biological/clinical aging parameters.

Conclusions

These results further corroborate our earlier report, stating that adjuvant TC chemotherapy does not significantly boost aging progression in elderly breast cancer patients. Our findings also endorsed specific age-related miRNAs as promising aging/frailty biomarkers in oncogeriatric populations.

Trial registration

ClinicalTrials.gov, NCT00849758. Registered on 20 February 2009. This clinical trial was registered prospectively.

Circulating microRNAs from the miR-106a-363 cluster on chromosome X as novel diagnostic biomarkers for breast cancer

PURPOSE

Novel noninvasive biomarkers with high sensitivity and specificity for the diagnosis of breast cancer (BC) are urgently needed in clinics. The aim of this study was to explore whether miRNAs from the miR-106a-363 cluster can be detected in the circulation of BC patients and whether these miRNAs can serve as potential diagnostic biomarkers.

METHODS

The expression of 12 miRNAs from the miR-106a-363 cluster was evaluated using qRT-PCR in 400 plasma samples (from 200 BC patients and 200 healthy controls (HCs)) and 406 serum samples (from 204 BC patients and 202 HCs) via a three-phase study. The identified miRNAs were further examined in tissues (32 paired breast tissues), plasma exosomes (from 32 BC patients and 32 HCs), and serum exosomes (from 32 BC patients and 32 HCs).

RESULTS

Upregulated levels of four plasma miRNAs (miR-106a-3p, miR-106a-5p, miR-20b-5p, and miR-92a-2-5p) and four serum miRNAs (miR-106a-5p, miR-19b-3p, miR-20b-5p, and miR-92a-3p) were identified and validated in BC. A plasma 4-miRNA panel and a serum 4-miRNA panel were constructed to discriminate BC patients from HCs. The areas under the receiver-operating characteristic curves of the plasma panel were 0.880, 0.902, and 0.858, and those of the serum panel were 0.910, 0.974, and 0.949 for the training, testing, and external validation phases, respectively. Two overlapping miRNAs (miR-106a-5p and miR-20b-5p) were consistently upregulated in BC tissues. Except for the expression of the plasma-derived exosomal miR-20b-5p, the expression patterns of exosomal miRNAs were concordant between plasma and serum, indicating the potential use of exosomal miRNAs as biomarkers.

CONCLUSION

We identified four plasma miRNAs and four serum miRNAs from the miR-106a-363 cluster as promising novel biomarkers for the diagnosis of BC.

Circulating microRNAs in breast cancer: novel diagnostic and prognostic biomarkers

Effective management of breast cancer depends on early diagnosis and proper monitoring of patients' response to therapy. However, these goals are difficult to achieve because of the lack of sensitive and specific biomarkers for early detection and for disease monitoring. Accumulating evidence in the past several years has highlighted the potential use of peripheral blood circulating nucleic acids such as DNA, mRNA and micro (mi)RNA in breast cancer diagnosis, prognosis and for monitoring response to anticancer therapy. Among these, circulating miRNA is increasingly recognized as a promising biomarker, given the ease with which miRNAs can be isolated and their structural stability under different conditions of sample processing and isolation. In this review, we provide current state-of-the-art of miRNA biogenesis, function and discuss the advantages, limitations, as well as pitfalls of using circulating miRNAs as diagnostic, prognostic or predictive biomarkers in breast cancer management.

A rapid and quantitative method to detect human circulating tumor cells in a preclinical animal model

Background

As cancer metastasis is the deadliest aspect of cancer, causing 90% of human deaths, evaluating the molecular mechanisms underlying this process is the major interest to those in the drug development field. Both therapeutic target identification and proof-of-concept experimentation in anti-cancer drug development require appropriate animal models, such as xenograft tumor transplantation in transgenic and knockout mice. In the progression of cancer metastasis, circulating tumor cells (CTCs) are the most critical factor in determining the prognosis of cancer patients. Several studies have demonstrated that measuring CTC-specific markers in a clinical setting (e.g., flow cytometry) can provide a current status of cancer development in patients. However, this useful technique has rarely been applied in the real-time monitoring of CTCs in preclinical animal models.

Methods

In this study, we designed a rapid and reliable detection method by combining a bioluminescent in vivo imaging system (IVIS) and quantitative polymerase chain reaction (QPCR)-based analysis to measure CTCs in animal blood. Using the IVIS Spectrum CT System with 3D–imaging on orthotropic-developed breast-tumor-bearing mice.

Results

In this manuscript, we established a quick and reliable method for measuring CTCs in a preclinical animal mode. The key to this technique is the use of specific human and mouse GUS primers on DNA/RNA of mouse peripheral blood under an absolute qPCR system. First, the high sensitivity of cancer cell detection on IVIS was presented by measuring the luciferase carried MDA-MB-231 cells from 5 to 5x10¹¹ cell numbers with great correlation (R² = 0.999). Next, the MDA-MB-231 cell numbers injected by tail vein and their IVIS radiance signals were strongly corrected with qPCR-calculated copy numbers (R² > 0.99). Furthermore, by applying an orthotropic implantation animal model, we successfully distinguished xenograft tumor-bearing mice and control mice with a significant difference (p < 0.001), whereas IVIS Spectrum-CT 3D–visualization showed that blood of mice with lung metastasis contained more than twice the CTC numbers than ordinary tumor-bearing mice. We demonstrated a positive correlation between lung metastasis status and CTC numbers in peripheral mouse blood.

Conclusion

Collectively, the techniques developed for this study resulted in the integration of CTC assessments into preclinical models both in vivo and ex vivo, which will facilitate translational targeted therapy in clinical practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3419-x) contains supplementary material, which is available to authorized users.

Circulating MicroRNAs in Cancer

It is believed that microRNAs have potential as circulating biomarkers of disease; however, successful clinical implementation remains a challenge. This chapter highlights broad variations in approaches to microRNA analysis where whole blood, serum and plasma have each been employed as viable sources. Further discrepancies in approaches are seen in endogenous controls and extraction methods utilized. This has resulted in contradictory publications, even when the same microRNA is targeted in the same disease setting.Analysis of blood samples highlighted the impact of both collection method and storage, on the microRNA profile. Analysis of a panel of microRNAs across whole blood, serum, and plasma originating from the same individual emphasized the impact of starting material on microRNA profile. This is a highly topical field of research with immense potential for translation into the clinical setting. Standardization of sample harvesting, processing and analysis will be key to this translation. Methods of sample harvesting, preservation, and analysis are outlined, with important mitigating factors highlighted.

Exosome-encapsulated microRNAs as circulating biomarkers for breast cancer

Breast cancer is a highly prevalent disease, accounting for 29% of invasive cancers in women. Survival from this disease depends on the stage at diagnosis, with patients who are detected earlier having more favourable outcomes. It is because of this that research groups are focusing on the development of a blood-based biomarker for breast cancer. Such biomarkers may facilitate the detection of breast cancer in its infancy before it has spread beyond the primary site. MicroRNAs (miRNAs) have shown immense potential in this setting. These short, non-coding RNA sequences have been shown to be dysregulated in breast cancer. Despite showing immense promise, miRNAs have not been successfully implemented in the clinical setting due to a lack of a standardised approach which has resulted in conflicting results. These challenges may be addressed at least in part through the study of exosomes. The biomarker potential for exosomes holds huge promise and may revolutionise the way in which we diagnose and manage breast cancer. These nanovesicles may be isolated from a variety of bodily fluids, including serum, and their miRNA content has been shown to reflect that of the parent breast cancer cell. This review will highlight the nomenclature and defining characteristics of exosomes, and current methods of isolation of serum-derived exosomes. Initial promising reports on the potential utility of exosomal miRNAs to be used as breast cancer biomarkers will also be addressed.

The diagnostic value of circulating microRNAs for middle-aged (40-60-year-old) coronary artery disease patients

OBJECTIVE

Circulating microRNAs have been recognized as promising biomarkers for various diseases. The present study aimed to explore the potential roles of circulating miR-149, miR-424 and miR-765 as non-invasive biomarkers for the diagnosis of coronary artery disease in middle-aged (40-60-year-old) patients.

METHODS

Sixty-five stable coronary artery disease patients (49-57 years old), 30 unstable coronary artery disease patients (49-58 years old), and 32 non-coronary artery disease patients (49--57 years old) who were matched for age, sex, smoking habits, hypertension and diabetes were enrolled in this study. Total RNA was isolated from plasma with TRIzol reagent. Circulating miRNA levels were measured by quantitative real-time polymerase chain reaction.

RESULTS

Circulating miR-149 levels were decreased 4.49-fold in stable coronary artery disease patients (1.18 ± 0.84) and 5.09-fold in unstable coronary artery disease patients (1.04 ± 0.65) compared with non-coronary artery disease patients (5.30 ± 2.57) (p<0.001). Circulating miR-424 levels were reduced 3.6-fold in stable coronary artery disease patients (1.18 ± 0.60) and 5-fold in unstable coronary artery disease patients (0.86 ± 0.54) compared with non-coronary artery disease patients (4.35 ± 2.20) (p<0.001). In contrast, circulating miR-765 levels were elevated 3.98-fold in stable coronary artery disease patients (6.09 ± 2.27) and 5.33-fold in unstable coronary artery disease patients (8.17 ± 2.77) compared with non-coronary artery disease patients (1.53 ± 0.99) (p<0.001). Receiver operating characteristic curve analysis revealed that the respective areas under the curve for circulating miR-149, miR-424 and miR-765 were 0.938, 0.919 and 0.968 in stable CAD patients and 0.951, 0.960 and 0.977 in unstable coronary artery disease patients compared with non-coronary artery disease patients.

CONCLUSION

Our results suggest that circulating miR-149, miR-424 and miR-765 might be novel, non-invasive biomarkers for the diagnosis of coronary artery disease in middle-aged patients. However, future prospective trials in large patient cohorts are necessary before reaching a solid conclusion.

Critical analysis of the potential for microRNA biomarkers in breast cancer management

Breast cancer is a complex and heterogeneous disease. Signaling by estrogen receptor (ER), progesterone receptor (PR), and/or human EGF-like receptor 2 (HER2) is a main driver in the development and progression of a large majority of breast tumors. Molecular characterization of primary tumors has identified major subtypes that correlate with ER/PR/HER2 status, and also subgroup divisions that indicate other molecular and cellular features of the tumors. While some of these research findings have been incorporated into clinical practice, several challenges remain to improve breast cancer management and patient survival, for which the integration of novel biomarkers into current practice should be beneficial. microRNAs (miRNAs) are a class of short non-coding regulatory RNAs with an etiological contribution to breast carcinogenesis. miRNA-based diagnostic and therapeutic applications are rapidly emerging as novel potential approaches to manage and treat breast cancer. Rapid technological development enables specific and sensitive detection of individual miRNAs or the entire miRNome in tissues, blood, and other biological specimens from breast cancer patients. This review focuses on recent miRNA research and its potential to address unmet clinical needs and challenges. The four sections presented discuss miRNA findings in the context of the following clinical challenges: biomarkers for early detection; prognostic and predictive biomarkers for treatment decisions using targeted therapies against ER and HER2; diagnostic and prognostic biomarkers for subgrouping of triple-negative breast cancer, for which there are currently no targeted therapies; and biomarkers for monitoring and characterization of metastatic breast cancer. The review concludes with a critical analysis of the current state of miRNA breast cancer research and the need for further studies using large patient cohorts under well-controlled conditions before considering the clinical implementation of miRNA biomarkers.