Fancysaint wrote:
cell research 最新一篇文章说 可以从血清中 检测 miRNA 从而诊断癌症
这篇文章的全文链接:http://www.nature.com/cr/journal/v18/n10/full/cr2008282a.html
Characterization of microRNAs in serum: a novel class of biomarkers for diagnosis of cancer and other diseases
Abstract
Dysregulated expression of microRNAs (miRNAs) in various tissues has been associated with a variety of diseases, including cancers. Here we demonstrate that miRNAs are present in the serum and plasma of humans and other animals such as mice, rats, bovine fetuses, calves, and horses. The levels of miRNAs in serum are stable, reproducible, and consistent among individuals of the same species. Employing Solexa, we sequenced all serum miRNAs of healthy Chinese subjects and found over 100 and 91 serum miRNAs in male and female subjects, respectively. We also identified specific expression patterns of serum miRNAs for lung cancer, colorectal cancer, and diabetes, providing evidence that serum miRNAs contain fingerprints for various diseases. Two non-small cell lung cancer-specific serum miRNAs obtained by Solexa were further validated in an independent trial of 75 healthy donors and 152 cancer patients, using quantitative reverse transcription polymerase chain reaction assays. Through these analyses, we conclude that serum miRNAs can serve as potential biomarkers for the detection of various cancers and other diseases.
Keywords: serum-microRNA, expression profile, fingerprint, blood-based biomarker, Solexa, cancers, diabetes
Introduction
Cancers, including lung cancer and colorectal cancer, are often diagnosed at a late stage with concomitant poor prognosis 1, 2, 3, 4. Although tumor markers greatly improve diagnosis, the invasive, unpleasant, and inconvenient nature of current diagnostic procedures limits their application 3, 4. Hence, there is a great need for identification of novel non-invasive biomarkers for early tumor detection. miRNAs, a class of naturally occurring small non-coding RNAs of 19-25 nucleotides (19-25 nt) in length, have recently been linked to cancer development 5, 6. Recently, altered miRNA expression has been reported in various cancers, and the profiles of tissue miRNAs exhibit great potential for an application in cancer definition 5, 6. In the present study, we report the surprising and exciting discovery that serum and plasma contain a large amount of stable miRNAs derived from various tissues/organs, and that the expression profile of these miRNAs shows great promise as a novel non-invasive biomarker for diagnosis of cancer and other diseases.
Discussion
The search for non-invasive tumor markers for diagnosis is currently one of the most rapidly growing areas in cancer research 1, 2, 3, 4. Serum and plasma have been the subject of extensive research for years 2. However, serum-based test suitable for widespread use in early tumor detection is currently limited 3, 4. Nowadays, almost all of the routinely used serum markers are proteins and the conventional methodologies used to measure them remain labor-intensive 3, 4. In the best currently available blood test, carcinoembryonic antigen exhibits low sensitivity and specificity, particularly in the context of early disease. Comprehensive proteomic analysis recently introduced a group of differentially expressed proteins as disease indicators and significantly increased the accuracy of diagnosis 11, 12, but its protein assay procedure is not easy to apply in clinical diagnosis.
The present study is the first one to systematically characterize miRNAs in serum. Our results demonstrate that serum miRNAs are stable and can be detected directly in serum, thereby greatly facilitating clinical use of such tests. Surprisingly, miRNAs, particularly serum miRNAs, are resistant to RNaseA digestion and other harsh conditions, which potentially explains the stability of serum miRNAs. The mechanism of resistance of miRNAs to RNase requires further study. Interestingly, we have found that miRNAs exist not only in human sera/plasma, but also in various animal species. Given that a lot of animals have been used for biomedical research and drug screening, serum miRNA expression profiles of these model animals can potentially serve as useful biomarkers in such studies. Thus, species-specific serum miRNA profiling would be of interest in the future. Furthermore, we have found that miRNAs also exist in other body fluids, including urine, tear, ascetic fluid, and amniotic fluid (data not shown). Obviously, studying miRNA expression profiles in these body fluids would be another important project.
Expression profile of serum miRNA in patients with NSCLC obtained by Solexa analysis shows 63 new miRNAs which are absent in normal subjects. Among these new miRNAs in LCS, many are known to be associated with lung cancer or other tumors. For instance, miR-128b, miR-152, miR-125b, miR-205, miR-27a, miR-146a, miR-222, miR-23a, miR-24, miR-150, etc. showed increased levels in tissue samples diagnosed with lung cancer, while the expression levels of miR-29a, miR-221, miR-223, miR-25, miR-92, miR-99a, etc. were increased in colorectal cancer tissues 10. Moreover, it has been reported that patients with papillary thyroid carcinomas showed increased levels of miR-221, miR-222, and miR-146 in the tumors 13. Likewise, miR-221, miR-222, and miR-125b were reported to be the top up-regulated miRNAs in TRAIL-resistant non-small cell lung cancer cells 14. However, among these newly detected serum miRNAs, there are also many, especially those with a high number designation, that have not been previously studied. Since our Solexa results clearly indicate the expression of these miRNAs in serum from cancer patients, their physiological functions and relationship with tumorigenesis should be further examined. The results also strongly suggest that, during diseases such as cancer, serum miRNAs are derived from not only circulating blood cells but also other tissues affected by ongoing diseases, and that these disease-related miRNAs in the serum can serve as potential biomarkers. Furthermore, different miRNA profiles in serum versus blood cells under the disease state again support the conclusion that the serum miRNA profile is not simply a default product of broken blood cells but serves as an indicator of biological function.
Comparing serum miRNA expression profile between patients with non-small cell lung cancer and colorectal cancer, we have found that most of these miRNAs seem to be involved in general tumorigenesis and cell division/growth. Perhaps most interesting is the fact that the Solexa results did identify a unique expression profile of serum miRNAs for each cancer type. For example, 8 and 14 serum miRNAs were uniquely detected in lung cancer and colorectal cancer patients, respectively. For lung cancer patients, the specific miRNAs included miR-205, miR-206, miR-335, etc. Some of these miRNAs such as miR-205 have been reported to be significantly up-regulated in bladder cancers 15. For colorectal cancer patients, those 14 miRNAs are miR-485-5p, miR-361-3p, miR-326, miR-487b, etc.
Our present study clearly demonstrates that levels of miRNAs in serum are stable, reproducible, and consistent among individuals of the same animal species. Interestingly, several groups reported that some RNA fragments, including miRNAs, occasionally have been found in serum and plasma, which might be related to certain dysfunctions 16, 17, 18. During the period when this manuscript was previously submitted elsewhere, Lawrie et al. 19 reported that miR-21 has the potential as a diagnostic biomarker for diffuse large B-cell lymphoma (DLBCL) and that the sera levels of miR-21 are associated with relapse-free survival in DLBCL patients. Mitchell et al. 20 most recently have found that serum levels of miR-141 can distinguish patients with prostate cancer from healthy controls. These studies, together with our results here, firmly support the notion that miRNAs are stably present in serum or plasma, and could serve as biomarkers for diseases. Moreover, our present study systematically characterized miRNAs in serum. Most importantly, we have identified serum miRNA expression profiles in normal subjects and various diseases. Single or a couple of serum-based biomarkers for one disease, such as AFP for liver cancer, or CRP for inflammation and diabetes etc., have been used for diagnosis over several decades. Lack of sufficient sensitivity, specificity, and accuracy is the limitation of a single blood-based biomarker in clinical use. By contrast, a cluster of biomarkers for one disease would be a better diagnostic tool with much higher sensitivity, specificity, and accuracy. We propose that the specific serum miRNA expression profile (not single or a couple of miRNA(s)) constitutes the fingerprint of a physiological or disease condition, which could have a huge impact on diagnosis and personalized medicine in the future.
In conclusion, we unequivocally show that serum contains large amounts of stable miRNAs derived from various tissues/organs and that the serum miRNA expression profile can be used as a novel serum-based biomarker potentially offering more sensitive and specific tests than those currently available for early diagnosis of cancer and other diseases. This new approach has the potential to revolutionize present clinical management, including determining cancer classification, estimating prognosis, predicting therapeutic efficacy, maintaining surveillance following surgery, as well as forecasting disease recrudescence. Furthermore, given the fact that miRNAs are identified as the first class of RNAs stably present in serum, it would be of great interest for future studies to both understand the biological functions and find other potential applications of serum miRNAs.
引用请注明出处!