Alzheimer’s disease (AD) is now the fifth leading cause of death in people over 65 years old. The prevalence of AD is increasing rapidly as the world population ages; data show that the incidence increases exponentially after the age of 65, with more than 40% of those aged over 85 now affected. According to a 2012 WHO report, nearly 36 million people globally are living with dementia, around two thirds of whom have AD, and this number is predicted to triple by 2050. The 18th World Alzheimer’s day on the 21st of September emphasized the need to reduce the stigma of dementia and make communities ‘dementia-friendly’. While these aims are laudable, the pressing need is for very early diagnosis and timely effective treatment if health services are not to be totally overwhelmed by the escalating numbers of AD patients needing care.
Two major abnormalities, clearly visible at autopsy, are present in abundance in the brains of AD patients, namely beta-amyloid plaques (Aβ) and neurofibrillary tangles (tau protein). However these lesions are not very evident using even advanced neuroimaging techniques, and the disease is most frequently diagnosed by psychological tests and rule-out of other causes of neurodegeneration, so that many early cases remain undiagnosed. Clinical research to allow early diagnosis has mainly focused on fluid biomarkers, and genetic risk factors and markers. Stanford University School of Medicine, USA, has been concentrating on the former approach with the aim of eventually developing a simple blood test that would confirm the onset of AD several years before clinical symptoms were apparent. Initially researchers compared signalling proteins from the blood of patients with and without AD. Their more recent work uses animal models to compare neurons from the hippocampal formation, which are very vulnerable and die in the early stages of AD, with neurons which are not affected until the late stages of the disease. Several labs based in Europe are concentrating on finding cerebrospinal fluid markers present in the early stages of AD, such as total tau, phosphorylated tau and the 42 amino acid form of Aβ, which would allow early specific and sensitive diagnosis. The search for genetic markers has demonstrated that the genes APOE and PICALM consistently affect Aβ.
Early diagnosis, however, must be followed by effective treatment. Currently cholinesterase inhibitors and NMDA receptor antagonists are used to alleviate symptoms but are not curative. Sadly just before this year’s World Alzheimer’s day it was announced that two antibody drugs targetting Aβ, namely Bapineuzumab from Pfizer and Solanezumab from Eli Lilly, had proved to be no better than placebo in Phase III clinical trials. Last year the European Parliament called for dedicated plans to reduce the burden of AD; a new funding model to ensure that big pharma doesn’t withdraw from the AD challenge could be the most valuable strategy.
Nucleic acids, which are among the best signatures of disease and pathogens, have traditionally been measured in centralised screening facilities using expensive instruments. Such tests are seldom available on point-of-care (POC) testing platforms. Advancements in simple microfluidics, cellphones and low-cost devices, isothermal and other novel amplification techniques, and reagent stabilisation approaches are now making it possible to bring some of the assays to POCs. This article highlights selected advancements in this area.
by Dr Robert Stedtfeld, Maggie Kronlein and Professor Syed Hashsham
Why point-of-care diagnostics?
Point-of-care diagnostics (POCs) bring selected capabilities of centralised screening to thousands of primary health care centres, hospitals, and clinics. Quick turnaround time, enhanced access to specialised testing by the physicians and patients, sample-in-result-out capability, simplicity, ruggedness and lower cost are among the leading reasons for the emergence of POCs. Another advantage of POCs is its flexibility to be adopted for assays that have received less attention and therefore are often “home brewed”, meaning an analyst develops it within the screening facility for routine patient care. The societal benefit–cost analysis of POCs may often exceed the traditional approaches by 10- to 100-fold. However, POCs must deliver the same quality of test results that is available with the existing centralised screening. Centralised screening is well established, has a performance record and analytical expertise ensuring reliability. POCs are emerging and, therefore, for successful integration into the overall healthcare system, POCs must provide an advantage over the existing system consisting of sample transport to a centralised location followed by analysis and reporting. Besides answering why POCs are better than the existing approaches, they must face validation and deployment challenges.
On the positive side, POCs are expected to have lower financial and acceptance barriers compared to what is faced by more expensive traditional approaches because of the need for lowering the cost of diagnostics in general. In 2011, the global in vitro testing market was $47.6 billion and projected to be $126.9 billion by 2022 (http://www.visiongain.com/). At present POCs constitute approximately one third of the total market – distributed in cardiac markers (31%), HbA1c (21%), cholesterol/lipids (16%), fecal occult blood (14%), cancer markers 98%), drug abuse (4%), and pregnancy (4%). Market forces critically determine the pace of technical development and deployment of POCs. Consider, for example, the global market for blood sugar testing (examples for genetic assays on POCs are non-existent) that is estimated to be $18 billion by 2015 and the alternative test, A1c that is only $272 million in 2012. Even though, A1c testing is now indispensable in managing diabetes, it has not received the priority it deserves due to much lower frequency of testing and therefore smaller market. Lowering the cost further, makes its deployment and diffusion even more challenging. Thus POCs must tackle the inherent bottleneck in their business model, i.e. how to succeed with an emerging or new technology, priced to be low cost, but without the access to market and high sales volumes – at least initially.
One option is to use the existing network of cellphones as one component of the POCs. Diagnostic tools based on cellphones and mobile devices have the potential to significantly reduce the economic burden and play an important role in providing universal healthcare. By 2015 the number of cellphone users will reach 1.4 billion and at least 500 million of them will have used health related applications (mHealth) in some form. Currently, more than 17,000 mHealth apps are available on various platforms. However, their ability to carry out genetic assays is yet to be harnessed. Out of the more than 2,500 genetic assays available, perhaps none are available on a mobile platform (GeneTests: www.genetests.org/). The coming decade is predicted to merge genomics, microfluidics and miniaturisation and multiply its impact many-fold by leveraging the resources and cellphone networks. Such platforms may allow the possibility of establishing an open source model for assays that are commercially not viable due to very low volumes.
A key question and the focus of this article is can genetic assays that are currently possible only in centralised screening facilities be carried out on POC platforms? We believe that through a combination of emerging molecular techniques, low-cost simple microfluidic systems, and some additional developments in detection systems and information transfer, it is possible to carry out genetic assays including mutation detection on POCs within the next 5 years and possibly sequencing within a decade.
Existing POC-adaptable genetic technologies
Nucleic acid-based amplification techniques remain the widely used analytical technique for genetic diagnostics. However, integrated systems capable of reliable detection with sensitivity and specificity required for clinical applications are still scarce. In centralised screening facilities, quantitative polymerase chain reaction (qPCR) is the workhorse for genetic analyses. Compared to qPCR, isothermal amplification strategies have been recognised as a promising alternative especially for POCs. This is because of the complexity of establishing the temperature cycling for qPCR and detection systems in POC devices. The advantages of isothermal amplification include high amplification yields (in some instances allowing a positive reaction to be observed with the naked eye), savings in power consumption without the need for temperature cycling, and low time to a positive amplification (as low as 5 minutes for larger copy numbers). Many isothermal techniques have been developed [1] including: loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), nucleic acid sequence-based amplification (NASBA), smart amplification process (SmartAmp), rolling circle amplification (RCA), multiple displacement amplification (MDA), helicase-dependent amplification (tHDA), strand displacement amplification (SDA), isothermal and chimeric primer-initiated amplification (ICAN), cross-priming amplification (CPA), single primer isothermal amplification (SPIA), self-sustained sequence replication reaction (3SR), transcription mediated amplification (TMA), genome exponential amplification reaction (GEAR) and exponential amplification reaction (EXPAR).
The benefits of one isothermal technique over another will depend on the application of interest. Techniques requiring a large number of enzymes and that are carried out at low temperature may be less amenable to POCs than those that require a single enzyme. More than one enzyme may, in general, increase the cost, rigor and complexity of the amplification reaction in a POC. While larger number of primer sets will increase the specificity, they will also make the design of primers to target a certain phylogenetic group or divergent functional gene more difficult, if not impossible. This is because of the need for multiple target specific regions, each being a certain distance (number of bases) between the other, and the increased complexity when trying to incorporate degenerate bases in multiple primer sequences within an assay. Isothermal assay enzymes that work at low temperature (less than 40°C) may have a disadvantage in hot and warm climatic conditions. However, an isothermal amplification strategy that directly incorporates primers/probes designed for previously validated qPCR assays, uses a single enzyme, can be performed at higher temperatures, and allows for accurate quantification, will greatly increase the attraction of isothermal amplification, ushering in a new era of point of care genetic diagnostics. The cost associated with licensing an amplification technique will also dictate if it can be used for POCs applications, specifically in low resource settings.
Existing POC platforms for genetic analysis
Multiple platforms have been developed for POC genetic testing with an emphasis on reduced costs, sizes, throughput, accuracy and simplicity. Table 1 is a non-exhaustive list to illustrate some of the capabilities. Ideally, POCs must simplify the genetic analysis by accepting crude or unprocessed samples. All of the listed qPCR platforms automatically perform sample processing (cell lysing and DNA purification) directly within the cartridge that the sample is dispensed. Compared to qPCR POCs, isothermal assay POCs have not focused as much on sample processing. There are two reasons for this. One, isothermal assays are generally less influenced by sample inhibitors and may not even require it in certain cases. Second, development of POCs based on isothermal assays has lagged because the assays themselves are relatively new for the diagnostics application.
Development of isothermal genetic POC devices, however, is relatively easier compared to qPCR devices. This is because isothermal genetic POCs utilise components that are inexpensive, smaller and have less power consumption. Use of such components is possible due to the high product yields of isothermal amplification techniques. LAMP, for example, produces 10 µg of DNA in a 25 µl volume compared to 0.2 µg in PCR. This high yield can be quantified with less sophisticated optics compared to those used in qPCR devices. The Gene-Z platform [figure 1], for example, uses an array of individually controlled low power light emitting diodes for excitation and optical fibres (one for each reaction well) for channelling the excitation light to a single photodiode detector for real time measurement [2].
Although POCs are generally considered as a single-assay device, multiplexing of targets (e.g. in co-infections) and analysing a given pathogen with greater depth (e.g. methicillin resistance Staphylococcus aureus, or HIV genotyping) is becoming absolutely critical. Genetic analysis is expected to allow resolution of genotype that is better than that possible by immunoassays. Use of simpler but powerful microfluidic chips (e.g. used with Gene-Z or GenePOC) instead of conventional Eppendorf tubes can be advantageous in terms of cost and power of analysis. Such microfluidic chips are increasingly changing their shape, form, and material and are bound to be simpler, better and more accessible. An example is the paper-based diagnostics platform developed by Whiteside’s group [3]. Miniaturisation obviously leads to significant reagent cost saving provided it does not run into detection-limit issues. Multiplexed detection also simplifies the analysis since manual dispensing into individual reaction tubes is not required. For example, the chip used with Gene-Z does not require external active elements for sealing, pumping, or distributing samples into individual reaction wells, eliminating potential for contamination between chips or to the device.
Type of genetic assays on POCs
So what types of genetic assays are more likely to move to POCs first? For regions with excellent centralised screening, it may be those assays where getting the results quickly using POCs saves lives or has tangible long term benefits, e.g. quickly deterring the infection and its antibiotic resistance. The leading example of this is MRSA, for which resistance has continuously increased over the past few decades. It is now known that patients are more likely to acquire MRSA in wards where the organism is screened by culturing compared to rapid molecular techniques. In such cases, detection of antibiotic resistance genes using a panel of genetic assays and POCs would minimise the practice of administering broad spectrum antibiotics because the results are not available soon enough.
In limited resource settings, the examples of genetic testing by POCs are literally endless – TB, malaria, dengue fever, HIV, flu, fungal infections and so on. This is because very little or no centralised screening occurs in such scenarios. The ability to measure dengue virus, for example, in 1–4 µl of blood could provide better tools to the 2.5 billion people who are at risk of infection and the 50–100 million people who do contract it every year. Similarly, multidrug-resistant and extensively drug-resistant TB is a global concern due to the high cost of treatment. At present, large numbers of mutations cannot be measured simultaneously using POCs. However, except the fact that isothermal mutation assays are fewer and the success rate for primer development is much lower than the signature marker probe/primer based assays, there are no technical barriers. The availability of a simple isothermal mutation assay will go a long way in making many genotyping-based diagnostics available on POCs.
In the long run, POCs may even be used to detect and quantify genetic markers associated with non-infectious diseases, such as cancer, and selected assays focusing on human genetics. Globally, cancer is responsible for 7.6 million deaths (2008 data) and projected to be rise to 13.1 million by 2030. Simple and quantitative tools capable of measuring a panel of markers may play an additional role – they may help collect data related to potentially useful but un-tested markers. Both PCR and isothermal-based assays are amenable to this application using circulating tumour cells, circulating free DNA/RNA, gene mutations, and microRNA panels. Currently utilised methods of cancer detection are highly invasive and time consuming. Minimally invasive methods on POCs may significantly increase the deployment of such capabilities.
Why do we need the wireless connectivity for POCs?
With POCs, comes the question of connectivity. Is it a must or good to have? We envision that it is important to have, but that a less useful form of device may be deployed without connectivity. Wireless connectivity via cellular phones has many advantages. Paramount among them is access to the physician and/or nurse for expert input and support. Technical advantages are automated data transfer, increased efficiency in reporting, saving time, lower equipment costs due to complexity of a touch-screen user interface and the computational power needed for data analysis.
The use of cellphones is an obvious possibility due to its ubiquitous availability and the vast network of mobile services. “There are 7 billion people on Earth; 5.1 billion own a cellphone; 4.2 billion own a toothbrush (Mobile Marketing Association Asia, 2011). By 2015 it is estimated that one third of cellphone users will have used mobile health solution in some form. However, POC genetic diagnostics and mobile networking have not yet crossed their paths. Some gene analysers (e.g. Gene-Z, Hunter) already have network enabled wireless connectivity to bridge these paths. More work is needed, however. One critical element is that transfer of data including through wireless mode must meet the requirements of the Health Insurance Portability and Accountability Act of 1996 (HIPAA) Privacy and Security Rules set by the U.S. Department of Health and Human Services. FDA clearance standards and specifications are still evolving for this area [4].
Impacts of the resulting products and devices are expected on both communicable and non-communicable diseases. Qualcomm Life provides a platform (2Net), that could be used for many different applications. According to them, “The 2Net platform is designed as an end-to-end, technology-agnostic cloud-based service that interconnects medical devices so that information is easily accessible by device users and their healthcare providers and caregivers” (http://www.qualcommlife.com/). Although the famous medical scanner or Tricorder of Star Wars fame is not yet possible, the recently announced $10 million prize by X-Prize Institute sponsored by Qualcom Life, for developing a Tricorder that can diagnose a set of 15 diseases without the intervention of the physician and weighs less than 2.3 kg is not too far from reality. In ten years, we should expect nothing less than a POC platform that is capable of sequencing-based diagnostics with assay cost of less than a dollar.
References
1. Craw P, Balachandran W. Isothermal nucleic acid amplification technologies for point-of-care diagnostics: a critical review. Lab Chip 2012; 12: 2469–2486.
2. Stedtfeld RD, Tourlousse DM, Seyrig G, Stedtfeld TM, Kronlein M, Price S, Ahmad F, Erdogan G, Tiedje JM, Hashsham SA. Gene-Z: a device for point of care genetic testing using a smartphone. Lab Chip 2012; 12: 1454–1462.
3. Martinez AW, Phillips ST, Whitesides GM, Carrilho E. Diagnostics for the developing world: microfluidic paper-based analytical devices. Anal Chem 2010; 82: 3–10.
4. Draft Guidance for Industry and Food and Drug Administration Staff – Mobile Medical Applications. July 21, 2011. www.fda.gov/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm263280.htm.
The authors
Robert Stedtfeld PhD, Maggie Kronlein and
Syed Hashsham, PhD*
Civil and Environmental Engineering
1449 Engineering Research Court Rm A127
Michigan State University
East Lansing, MI 48824, USA
*Corresponding author:
E-mail: hashsham@egr.msu.edu
Melanoma is the most malignant type of all skin neoplasms. Although current clinical, morphologic, pathologic, and biochemical methods provide insights into disease behaviour and outcome, melanoma is still an unpredictable disease. Once in an advanced stage, it remains a fatal neoplasm with few therapeutic options. Therefore, significant efforts still need to be made in finding suitable biomarkers that could aid or improve its early diagnosis, its correct staging, the discrimination of other pathological conditions as well as indicate patients’ prognosis or the most appropriate therapeutic regimes. On the other hand, well-defined diagnostic markers are necessary to avoid the apparent overdiagnosis of melanoma.
by Prof. J. Pietzsch, N. Tandler and Dr B. Mosch
Malignant melanoma: the need for biomarkers
Melanoma incidence and mortality have been steadily increasing in almost all countries and in fair-skinned populations in particular. For example, in Germany in 2009 incidence rates (mortality rates) of cutaneous melanoma were 17.4 (2.6) per 100 000 males and 16.0 (1.7) per 100 000 females, with cutaneous melanoma responsible for about 1.3% of all cancer deaths (Association of Population-based Cancer Registries in Germany, GEKID; http://www.gekid.de).
Considering variations between countries, 5-year survival for people of all races diagnosed with primary cutaneous melanoma <1.5 mm in depth is about 90%, amounting to 99% for local disease. The 5-year survival for people diagnosed with mucosal and intraocular melanoma is about 70%. However, 5-year survival is only 60–65% if the disease has spread within the region of the primary melanoma, dramatically dropping to below 10% if widespread. Although screening campaigns and intensive public health programmes resulted in decreasing incidence rates in, particularly, younger age groups, the incidence and burden of melanoma continue to rise. This is mainly due to the aging population, continued high recreational sun exposure habits, changing climate patterns, and increasing environmental contamination with carcinogenic agents [1, 2].
Thus, sensitive screening and early detection of high risk groups, and, on the other hand, personalization of therapy are the major principles of melanoma control. In this regard, biomarkers represent molecular attributes of the individual patient that will not only allow for detection and diagnosis, but also answer questions about the biologic behaviour of the tumour and metastases, mechanisms of resistance and/or sensitivity to therapy.
Prospectively, melanoma therapy will substantially be improved by the use of biomarkers that (i) offer the potential to identify and treat melanoma before it is clearly visible or symptomatic, (ii) will facilitate easy detection without even minimal surgical procedure, and (iii) will also be candidates for population-based screenings. In this regard, this article briefly summarizes the current trends and perspectives in malignant melanoma biomarker research as recently reviewed and discussed in more detail by us [1, cf. references therein].
The characteristics of a good biomarker
Melanoma biomarkers can be divided into different categories. Most of them show higher expression in melanoma cells than in normal tissue and, therefore, are used as diagnostic markers. Other biomarkers may serve as prognostic or predictive markers because of their increased expression in advanced stages of disease, as indicators of treatment response and/or of disease recurrence during follow-up. Moreover, melanoma progenitor/stem cell markers are of potential use for identification of cell subpopulations that exhibit specifically critical properties like high carcinogenicity, metastatic potency, and treatment resistance.
The ideal serological biomarker should be a metabolically and analytically stable molecule detectable and/or quantifiable in the blood or other body fluid compartments, which are accessible by minimally invasive procedures. The biomarker should allow for the diagnosis of a growing tumour in a patient or for prediction of the likely response of a patient to a certain treatment, even earlier or better than by applying clinical imaging modalities. Hence, the biomarker must exhibit sufficient sensitivity and specificity in order to minimize false-negative as well as false-positive results [1, 3].
Importantly, at the moment, no ideal biomarker exists in the melanoma field. Pathologic characteristics of the primary melanoma, e.g., tumour thickness (Breslow index), mitotic rate, and ulceration are important prognostic factors. However, these characteristics can only be determined after localization and biopsy or surgical resection of the tumour. Regarding the points above, either circulating melanoma cells or melanoma-associated extracellular molecules provide suitable non-invasive analytical access.
Current and potential biomarkers for malignant melanoma
Melanoma cells release many proteins and other molecules into the extracellular fluid. Some of these molecules can end up in the bloodstream and hence serve as potential serum biomarkers. From a pathobiochemical point of view these biomarkers comprise molecules released by (i) necrotic cell content release, (ii) active secretion by melanoma cells, and (iii) ectodomain membrane shedding, including enzymes, soluble proteins/antigens, melanin-related metabolites, and circulating cell-free nucleic acids [1] [Table 1]. These molecules exhibit different prognostic and predictive values in melanoma diagnosis, staging, and treatment monitoring [1, 3–5].
Serum lactate dehydrogenase
In the American Joint Committee on Cancer (AJCC) staging system, serum lactate dehydrogenase (LDH) is the only serum biomarker that was accepted as a strong prognostic parameter in clinical routine for melanoma classifying those patients with elevated serum levels in stage IV M1C [3, 6].
Despite many promising results, there are also some limitations in measuring LDH as melanoma biomarker. First of all, LDH is not an actively secreted enzyme. Thus, LDH is only released through cell damage and cell death, which occur more frequently in malignant neoplasms. However, there are also false-positive values through hemolysis, hepatocellular injuries like hepatitis, myocardial infarction, muscle diseases, and other infectious diseases with high amounts of necrotic cells [3]. Moreover, LDH is non-specific for melanoma and elevated levels are also found in many other benign and malignant diseases.
Tyrosinase mRNA
An indicator for the presence of circulating melanoma cells and increased probability of the occurrence of metastases is the detection of tyrosinase mRNA in peripheral blood. Although the serological analyte is actually a nucleic acid isolated from circulating melanoma cells tyrosinase often is considered as an enzyme biomarker in melanoma [1, 3].
Due to the fact that tyrosinase mRNA is detected through nested RT-PCR the analytical sensitivity is very high. It is possible to detect one melanoma cell among 106 of normal blood cells. In recent decades, however, tyrosinase mRNA expression was determined in many different studies resulting in a wide range of variability (30–100%). One reason might be the transient presence of tumour cells in the bloodstream. On the other hand, non-standardized protocols for PCR-based techniques contribute to the observed variability, lower sensitivity, and different thresholds for melanoma cell detection.
Matrix metalloproteinases and cyclooxygenase-2
Further enzyme markers comprise matrix metalloproteinases and cyclooxygenase-2, with the latter detected via certain circulating eicosanoid products of the enzyme reaction [1, 7].
S100 calcium binding proteins
In addition, the S100 family of calcium binding proteins gained importance as both potential molecular key players and biomarkers in the etiology, progression, manifestation, and therapy of neoplastic disorders, including malignant melanoma. Moreover, S100 proteins receive attention as possible targets of therapeutic intervention moving closer to clinical impact.
In this regard, to-date, the best-studied S100 protein in melanoma is S100B [8, 9]. Increased S100B serum levels in melanoma patients chiefly have been attributed to the loss of cell integrity and proteolytic degradation as a result of apoptosis and necrosis of tumour cells. S100B seems to be the most promising serum marker for advanced melanoma, even more specific and sensitive than LDH, but is not yet applied in the clinical routine [1, 10].
Another member of the S100 family, the metastasis-associated protein S100A4 influences cell motility, angiogenesis, and apoptosis. The mechanism by which S100A4 stimulates metastasis is still under investigation; however, extracellular S100A4 seems to be of major importance in this context and, therefore, possibly might serve as a blood marker. Despite some early promising results on the use of S100A4 serum levels as a prognostic marker in melanoma, the greatest problem might be the low protein concentration in the blood which impedes clinical relevance [1]. This seems to be also true for other S100 proteins that are suggested to be biomarker candidates of melanoma. As more specific reagents for individual S100 proteins are being generated, their potential diagnostic and prognostic usage will increase substantially [1, 9].
Other candidate biomarkers
Other soluble proteins considered as melanoma biomarker candidates are given in Table 1. Furthermore, various non-protein biomarkers are potential targets for melanoma biomarker research. Those comprise metabolites of the melanin synthesis pathways, originating from the amino acid L-tyrosine, and cell-free nucleic acids [1].
Future directions in melanoma biomarker discovery
As well as the markers discussed above, other proteins, some of them possibly representing melanoma progenitor/stem cell-like markers, can be detected in circulating melanoma cells, at least as demonstrated in animal models. This includes ATP-binding cassette (ABC) multidrug transporters and neuroepithelial intermediate filament nestin [1, 5]. These markers offer the potential to predict the risk of progression to metastatic disease states, treatment resistance, and disease relapse. Lack of sufficient sensitivity, specificity, and accuracy are the most relevant limitations of a single blood-based melanoma biomarker for clinical use.
By contrast, a cluster of biomarkers for one disease would be a better diagnostic tool with much higher sensitivity, specificity, and clinical accuracy. Therefore, new investigations, called ´proteomic profiling´, focus on the identification of multiple co-expressed biomarkers or signature biomarker patterns, which allow early detection, staging, therapeutic monitoring and prognostic predictions [4, 11, 12].
Abbreviations
Biomarker abbreviations: 6H5MI2C, 6-hydroxy-5-methoxyindole-2-carboxylic acid; CEACAM, carcinoembryonic antigen-related cell adhesion molecule 1; CYT-MAA, cytoplasmic melanoma associated antigen; MAGE, melanoma associated antigen-1; MART-1, melanoma antigen recognized by T-cells 1; MIA, melanoma inhibitory activity; MMP, matrix metalloproteinase; sICAM, soluble intercellular adhesion molecule 1; sVCAM, soluble vascular cell adhesion molecule 1; TA90, tumour-associated antigen 90; VEGF, vascular endothelial growth factor; YKL-40, heparin- and chitin-binding lectin YKL-40 (syn. human cartilage glycoprotein-39)
Method abbreviations: ELISA, enzyme-linked immunosorbent assay; HPLC, high performance liquid chromatography; IHC, immunohistochemistry; IP, immunoprecipitation; LIA, luminescence immunoassay; RT-PCR, reverse transcription polymerase chain reaction; TMA, tissue microarray
This publication summarizes a comprehensive review article on protein and non-protein biomarkers in melanoma recently published by the authors [1, cf. references therein].
References
1. Tandler N, Mosch B, Pietzsch J. Protein and non-protein biomarkers in melanoma: a critical update. Amino Acids 2012; 43: 2203–2230.
2. De Giorgi V, Gori A, Grazzini M, et al. Epidemiology of melanoma: is it still epidemic? What is the role of the sun, sunbeds, Vit D, betablocks, and others? Dermatol Ther 2012; 25: 392–396.
3. Vereecken P, Cornelis F, Van Baren N, et al. A synopsis of serum biomarkers in cutaneous melanoma patients. Dermatol Res Pract 2012; 2012: 260643.
4. Palmer SR, Erickson LA, Ichetovkin I, et al. Circulating serologic and molecular biomarkers in malignant melanoma. Mayo Clin Proc 2011; 86: 981–990.
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10. Weide B, Elsässer M, Büttner P, et al. Serum markers lactate dehydrogenase and S100B predict independently disease outcome in melanoma patients with distant metastasis. Br J Cancer 2012; 107: 422–428.
11. Solassol J, Du-Thanh A, Maudelonde T, et al. Serum proteomic profiling reveals potential biomarkers for cutaneous malignant melanoma. Int J Biol Markers 2011; 26: 82–87.
12. Pham TV, Piersma SR, Oudgenoeg G, Jimenez CR. Label-free mass spectrometry-based proteomics for biomarker discovery and validation. Expert Rev Mol Diagn 2012; 12: 343–359.
Acknowledgements
Nadine Tandler is the recipient of a fellowship from the Europäische Sozialfonds (ESF).
The authors
Jens Pietzsch*, PhD, MD, Nadine Tandler, MSc and Birgit Mosch, PhD
Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
*Corresponding author
E-mail: j.pietzsch@hzdr.de
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