Cancer Liquid Biopsy Using Integrated Microfluidic Exosome Analysis Platforms

Liquid biopsies serve as both powerful noninvasive diagnostic tools for early cancer screening and prognostic tools for monitoring cancer progression and treatment efficacy. Exosomes are promising biomarkers for liquid biopsies, since these nano‐sized extracellular vesicles (EVs) enrich proteins, lipids, mRNAs, and miRNAs from cells of origin, including cancer cells. Although exosomes are abundantly present in various bodily fluids, conventional exosome isolation and detection methods that rely on benchtop equipment are time‐consuming, expensive, and involve complicated non‐portable procedures. As an alternative, recently developed microfluidic platforms can perform effective exosome separation and detection for liquid biopsies using a single device. Such methods offer advantages of integrity, speed, cost‐efficiency, and portability over conventional benchtop and early microfluidic‐based single‐functional methods which can only separate or detect exosomes separately. These advances have made exosome‐based point‐of‐care (POC) applications possible. This review outlines recent integrated microfluidic‐based exosomal detection strategies to guide future development of such devices for use in liquid biopsies for early cancer screening, prognostic monitoring, and other potential POC applications.     

MicroRNAs as oncogenes or tumour suppressors in oesophageal cancer: potential biomarkers and therapeutic targets

MicroRNAs are a class of small, non‐coding RNAs that can negatively regulate protein‐coding genes, and are associated with almost all known physiological and pathological processes, especially cancer. The number of studies documenting miRNA expression patterns in malignancy continues to expand rapidly, with continuously gained critical information regarding how aberrantly expressed miRNAs may contribute to carcinogenesis. miRNAs can influence cancer pathogenesis, playing a potential role as either oncogenes or tumour suppressors. Recently, several miRNAs have been reported to exert different regulatory functions in oesophageal cancer – the carcinoma typically arising from the epithelial lining of the oesophagus. These miRNAs also have potential clinical applications towards developing biomarkers or targets for possible use in diagnosis or therapy in oesophageal cancer. In this review, we have summarized the two (oncogenic or tumour suppressive) roles of miRNAs here, and their applications as potential biomarkers or therapeutic targets, which may illuminate future treatment for oesophageal cancer.     

MicroRNAs as potential investigative and predictive biomarkers in colorectal cancer

Colorectal cancer (CRC) is a noticeable reason of cancer-associated deaths with a high incidence and mortality rate. Countless effort have been put into the improving clinical management of CRC patients including more effective tools and a wide variety of biomarkers for diagnostic, prognostic or predictive purposes. In recent years, dysregulated miRNAs have been emerged as highly sensitive and specific markers to manage CRC in an effective way. They can play key roles in carcinogenesis as potential oncogenes, tumor suppressors or regulators of cancer network. Therefore, miRNAs may serve as molecular tools that can be quantified and used in diagnostic and prognostic approaches. Growing evidence also suggests that forced expression of tumor suppressor miRNAs or inhibiting the oncogene ones, can be used as a novel treatment strategy. In this review, we focus on the clinical applications of miRNAs as promising biomarkers of early cancer detection, prognosis and treatment.     

Direct tissue proteomics in human diseases: potential applications to melanoma research

Although the rates of cancer are stabilizing, the number of new invasive melanoma continues to rise. Melanoma represents only 4% of all skin cancers, but nearly 80% of skin cancer deaths. In loss of potential productive life-years, it is second only to adult leukemia. Once melanoma spreads to regional and distant sites, the chance of cure decreases significantly. Unfortunately, current diagnostic and prognostic methods are often inadequate. More precise staging and disease characterization will lead to new and more rational approaches to treatment. Proteomics is a fast-growing discipline in biomedicine that can be defined as the global characterization and differential expression of the entire protein complement of a cell, tissue or organism. Despite major advances in molecular approaches to the diagnosis and prognostication of human diseases such as melanoma, there remain significant obstacles in applying the proteomic technologies to clinical samples to extract important biological information. The application of a shotgun-based technique termed direct tissue proteomics with improved extraction protocol of proteins from formalin-fixed paraffin-embedded tissue would enable retrospective biomarker investigations of the vast archive of pathologically characterized clinical samples that exist worldwide. Combination of this direct tissue proteomics method with laser-capture microdissection may assist in the discovery of new biomarkers and may lead to new diagnostic tests, risk assessment and staging tools as well as improvement in therapeutics. In addition, these tools can provide a molecular characterization of melanoma, which may enable individualized molecular therapy.     

Direct tissue proteomics in human diseases: potential applications to melanoma research

Although the rates of cancer are stabilizing, the number of new invasive melanoma continues to rise. Melanoma represents only 4% of all skin cancers, but nearly 80% of skin cancer deaths. In loss of potential productive life-years, it is second only to adult leukemia. Once melanoma spreads to regional and distant sites, the chance of cure decreases significantly. Unfortunately, current diagnostic and prognostic methods are often inadequate. More precise staging and disease characterization will lead to new and more rational approaches to treatment. Proteomics is a fast-growing discipline in biomedicine that can be defined as the global characterization and differential expression of the entire protein complement of a cell, tissue or organism. Despite major advances in molecular approaches to the diagnosis and prognostication of human diseases such as melanoma, there remain significant obstacles in applying the proteomic technologies to clinical samples to extract important biological information. The application of a shotgun-based technique termed direct tissue proteomics with improved extraction protocol of proteins from formalin-fixed paraffin-embedded tissue would enable retrospective biomarker investigations of the vast archive of pathologically characterized clinical samples that exist worldwide. Combination of this direct tissue proteomics method with laser-capture microdissection may assist in the discovery of new biomarkers and may lead to new diagnostic tests, risk assessment and staging tools as well as improvement in therapeutics. In addition, these tools can provide a molecular characterization of melanoma, which may enable individualized molecular therapy.     

Molecular markers in malignant cutaneous melanoma: Gift horse or one‐trick pony?

The management of malignant cutaneous melanoma is problematic. Current clinical prognostic factors do not adequately predict disease recurrence and overall survival in a significant subset of patients. Adjuvant therapies for melanoma are notoriously toxic and associated with significant morbidity. Furthermore, it has been difficult to predict which patients will respond best to these treatments, if at all. DNA and RNA biomarkers have been developed to help overcome these problems. Biomarkers have been shown to upstage patients with melanoma, but are the assays sensitive and specific enough for clinical use as predictors of disease outcome or treatment response? We review our experience with DNA and RNA biomarkers in terms of their prognostic and predictive capabilities in malignant melanoma and outline their likely role in the future of melanoma staging, surveillance, and treatment. © 2005 Wiley‐Liss, Inc.     

Regulation of cancer aggressive features in melanoma cells by microRNAs

MicroRNAs (miRNAs) are small non-coding RNAs with regulatory roles, which are involved in a broad spectrum of physiological and pathological processes, including cancer. A common strategy for identification of miRNAs involved in cell transformation is to compare malignant cells to normal cells. Here we focus on identification of miRNAs that regulate the aggressive phenotype of melanoma cells. To avoid differences due to genetic background, a comparative high-throughput miRNA profiling was performed on two isogenic human melanoma cell lines that display major differences in their net proliferation, invasion and tube formation activities. This screening revealed two major cohorts of differentially expressed miRNAs. We speculated that miRNAs up-regulated in the more-aggressive cell line contribute oncogenic features, while the down-regulated miRNAs are tumor suppressive. This assumption was further tested experimentally on five candidate tumor suppressive miRNAs (miR-31, -34a, -184, -185 and -204) and on one candidate oncogenic miRNA (miR-17-5p), all of which have never been reported before in cutaneous melanoma. Remarkably, all candidate Suppressive-miRNAs inhibited net proliferation, invasion or tube formation, while miR-17-5p enhanced cell proliferation. miR-34a and miR-185 were further shown to inhibit the growth of melanoma xenografts when implanted in SCID-NOD mice. Finally, all six candidate miRNAs were detected in 15 different metastatic melanoma specimens, attesting for the physiological relevance of our findings. Collectively, these findings may prove instrumental for understanding mechanisms of disease and for development of novel therapeutic and staging technologies for melanoma.     

MicroRNA‐378 regulates epithelial–mesenchymal transition and metastasis of melanoma by inhibiting FOXN3 expression through the Wnt/β‐catenin pathway

MicroRNAs (miRNAs) participate in the development and progression of melanoma. However, while dysregulation of microRNA‐378 (miR‐378) has been seen in various cancer types, its clinical importance and function in melanoma are poorly elucidated. In this work, miR‐378 expression in melanoma and in adjacent non‐cancerous tissue was evaluated with a quantitative real‐time polymerase chain reaction. A series of assays (wound healing, Transwell, and nude mouse subcutaneous tumor model) were used to investigate the implications of abnormal miR‐378 regulation on melanoma cell migration and invasion in vitro, and on tumorigenicity in vivo. Prediction and conformation of the miR‐378 target gene was undertaken using bioinformatic analysis and luciferase reporter system. Expression of miR‐378 was often increased in melanoma, and shown to potentiate its migration, invasion, and tumorigenicity. miR‐378 acted, at least partially, through inhibition of the potential target FOXN3 and via Wnt/β‐catenin pathway activation. The findings indicate that miR‐378 triggers melanoma development and progression. This miRNA could be a novel diagnostic and prognostic biological marker and provide utility for targeted treatment of melanoma.     

Circulating miRNAs in cancer: from detection to therapy

Since the discovery of circulating microRNAs (miRNAs) in body fluids, an increasing number of studies have focused on their potential as non-invasive biomarkers and as therapeutic targets or tools for many diseases, particularly for cancers. Because of their stability, miRNAs are easily detectable in body fluids. Extracellular miRNAs have potential as biomarkers for the prediction and prognosis of cancer. Moreover, they also enable communication between cells within the tumor microenvironment, thereby influencing tumorigenesis. In this review, we summarize the progresses made over the past decade regarding circulating miRNAs, from the development of detection methods to their clinical application as biomarkers and therapeutic tools for cancer. We also discuss the advantages and limitations of different detection methods and the pathways of circulating miRNAs in cell-cell communication, in addition to their clinical pharmacokinetics and toxicity in human organs. Finally, we highlight the potential of circulating miRNAs in clinical applications for cancer.     

Cell‐free microRNAs in blood and other body fluids,as cancer biomarkers

The discovery of cell‐free microRNAs (miRNAs) in serum, plasma and other body fluids has yielded an invaluable potential source of non‐invasive biomarkers for cancer and other non‐malignant diseases. miRNAs in the blood and other body fluids are highly stable in biological samples and are resistant to environmental conditions, such as freezing, thawing or enzymatic degradation, which makes them convenient as potential biomarkers. In addition, they are more easily sampled than tissue miRNAs. Altered levels of cell‐free miRNAs have been found in every type of cancer analysed, and increasing evidence indicates that they may participate in carcinogenesis by acting as cell‐to‐cell signalling molecules. This review summarizes the biological characteristics and mechanisms of release of cell‐free miRNAs that make them promising candidates as non‐invasive biomarkers of cancer.     

Long non‐coding RNAs in melanoma

Melanoma is the most lethal cutaneous cancer with a highly aggressive and metastatic phenotype. While recent genetic and epigenetic studies have shed new insights into the mechanism of melanoma development, the involvement of regulatory non‐coding RNAs remain unclear. Long non‐coding RNAs (lncRNAs) are a group of endogenous non‐protein‐coding RNAs with the capacity to regulate gene expression at multiple levels. Recent evidences have shown that lncRNAs can regulate many cellular processes, such as cell proliferation, differentiation, migration and invasion. In the melanoma, deregulation of a number of lncRNAs, such as HOTAIR, MALAT1, BANCR, ANRIL, SPRY‐IT1 and SAMMSON, have been reported. Our review summarizes the functional role of lncRNAs in melanoma and their potential clinical application for diagnosis, prognostication and treatment.     

A Functional Screen Identifies Specific MicroRNAs Capable of Inhibiting Human Melanoma Cell Viability

Malignant melanoma is an aggressive form of skin cancer with poor prognosis. Despite improvements in awareness and prevention of this disease, its incidence is rapidly increasing. MicroRNAs (miRNAs) are a class of small RNA molecules that regulate cellular processes by repressing messenger RNAs (mRNAs) with partially complementary target sites. Several miRNAs have already been shown to attenuate cancer phenotypes, by limiting proliferation, invasiveness, tumor angiogenesis, and stemness. Here, we employed a genome-scale lentiviral human miRNA expression library to systematically survey which miRNAs are able to decrease A375 melanoma cell viability. We highlight the strongest inhibitors of melanoma cell proliferation, including the miR-15/16, miR-141/200a and miR-96/182 families of miRNAs and miR-203. Ectopic expression of these miRNAs resulted in long-term inhibition of melanoma cell expansion, both in vitro and in vivo. We show specifically miR-16, miR-497, miR-96 and miR-182 are efficient effectors when introduced as synthetic miRNAs in several melanoma cell lines. Our study provides a comprehensive interrogation of miRNAs that interfere with melanoma cell proliferation and viability, and offers a selection of miRNAs that are especially promising candidates for application in melanoma therapy.     

Identification of canine circulating miRNAs as tumor biospecific markers using Next-Generation Sequencing and Q-RT-PCR

Delay in cancer diagnosis often results in metastasis and an inability to successfully treat the tumor. The use of broadly cancer-specific biomarkers at an early stage may improve cancer treatment and staging. This study has explored circulatory exosomal miRNAs as potential diagnostic biomarkers to identify cancer patients. Secretory exosomal miRNAs were isolated from 13 canine cancer cell lines (lymphoma, mast cell tumor, histiocytic cell line, osteosarcoma, melanoma, and breast tumor) and were sequenced by Next-Generation sequencing (NGS). We have identified 6 miRNAs (cfa-miR-9, -1841, ?1306, ?345, ?132, and ?26b) by NGS that were elevated in all cancer cell types. The miRNAs identified by NGS were then examined by Q-RT-PCR. The PCR data demonstrated similar expression patterns to those seen with NGS but provided fold differences that were much lower than those seen for NGS. Cfa-miR-9 was found to be the most consistently elevated miRNA in NGS and PCR, making it the most likely miRNA to prove diagnostic. In this study, we have demonstrated that it is possible to identify exosomal miRNAs with elevated secretion across multiple tumor types that could be used as circulatory diagnostic biomarkers for liquid biopsy in the future.     

Emerging strategies to treat rare and intractable subtypes of melanoma

Melanoma is the deadliest form of skin cancer, possessing a diverse landscape of subtypes with distinct molecular signatures and levels of aggressiveness. Although immense progress has been achieved therapeutically for patients with the most common forms of this disease, little is known of how to effectively treat patients with rarer subtypes of melanoma. These subtypes include acral lentiginous (the rarest form of cutaneous melanoma; AL), uveal, and mucosal melanomas, which display variations in distribution across (a) the world, (b) patient age‐groups, and (c) anatomic sites. Unfortunately, patients with these relatively rare subtypes of melanoma typically respond worse to therapies approved for the more common, non‐AL cutaneous melanoma and do not have effective alternatives, and thus consequently have worse overall survival rates. Achieving durable therapeutic responses in these high‐risk melanoma subtypes represents one of the greatest challenges of the field. This review aims to collate and highlight effective preclinical and/or clinical strategies against these rare forms of melanoma.     

以微小RNA作为新型标志物检测循环肿瘤细胞及其临床意义

循环肿瘤细胞（circulating tumor cell,CTC）是随血液循环一起转运的实体肿瘤细胞,与实体肿瘤的发展、转移、复发和预后等关系密切。然而,CTC数量的稀少使有效检测CTC具有较大的挑战性。微小RNA（microRNA,miRNA）作为一类新发现的基因表达调控分子,在肿瘤的发生、发展、转归等过程中起着重要的作用。CTC关联性miRNA的研究为CTC的检测和肿瘤的诊治开创了新思路。该文介绍了CTC的临床意义和主要分析方法,在CTC关联性miRNA与肿瘤诊断、治疗和预后等方面总结了这类新型肿瘤细胞标志物的研究进展。