gp100 mRNA is more sensitive than tyrosinase mRNA for RT-PCR amplification to detect circulating melanoma cells in peripheral blood of melanoma patients

TRIB2 as a biomarker for diagnosis and progression of melanoma

Malignant melanoma is the most deadly form of skin cancer. There is a critical need to identify the patients that could be successfully treated by surgery alone and those that require adjuvant treatment. In this study, we demonstrate that the expression of tribbles2 (TRIB2) strongly correlates with both the presence and progression of melanocyte-derived malignancies. We examined the expression of TRIB2 in addition to 12 previously described melanoma biomarkers across three independent full genome microarray studies. TRIB2 expression was consistently and significantly increased in benign nevi and melanoma, and was highest in samples from patients with metastatic melanoma. The expression profiles for the 12 biomarkers were poorly conserved throughout these studies with only TYR, S100B and SPP1 showing consistently elevated expression in metastatic melanoma versus normal skin. Strikingly we confirmed these findings in 20 freshly obtained primary melanoma tissue samples from metastatic lesions where the expression of these biomarkers were evaluated revealing that TRIB2 expression correlated with disease stage and clinical prognosis. Our results suggest that TRIB2 is a meaningful biomarker reflecting diagnosis and progression of melanoma, as well as predicting clinical response to chemotherapy.

An electrochemical immunosensing method for detecting melanoma cells

An electrochemical immunosensing method was developed to detect melanoma cells based on the affinity between cell surface melanocortin 1 receptor (MC1R) antigen and anti-MC1R antibody (MC1R-Ab). The MC1R-Abs were immobilized in amino-functionalized silica nanoparticles (n-SiNPs)-polypyrrole (PPy) nanocomposite modified on working electrode surface of screen-printed electrode (SPE). Cyclic voltammetry was employed, with the help of redox mediator ([Fe(CN)6](3-)), to measure the change in anodic oxidation peak current arising due to the specific interaction between MC1R antigens and MC1R-Abs when the target melanoma cells are present in the sample. Various factors affecting the sensor performance, such as the amount of MC1R-Abs loaded, incubation time with the target melanoma cells, the presence of interfering non-melanoma cells, were tested and optimized over different expected melanoma cell loads in the range of 50-7500 cells/2.5 mL. The immunosensor is highly sensitive (20 cells/mL), specific, and reproducible, and the antibody-loaded electrode in ready-to-use stage is stable over two weeks. Thus, in conjunction with a microfluidic lab-on-a-chip device our electrochemical immunosensing approach may be suitable for highly sensitive, selective, and rapid detection of circulating tumor cells (CTCs) in blood samples.

Circulating serologic and molecular biomarkers in malignant melanoma

The worldwide incidence of malignant melanoma has been increasing during the past decade and is a public health concern because this disease accounts for up to 90% of deaths from cutaneous malignancies. It remains a devastating disease with few therapeutic options once in an advanced stage. Current methods of detection, prognostication, and monitoring of melanoma focus on clinical, morphologic, and histopathologic characteristics of measurable tumor. Although this information provides some insight into disease behavior and outcome, melanoma is still an unpredictable disease. Significant effort has been put into finding an informative serologic biomarker. However, the marker remains elusive, and investigations continue. Using the PubMed database, we reviewed the published literature on serologic melanoma biomarkers and present a synopsis of the extensive investigations that have been performed thus far, provide some insight into why most have failed to become incorporated into routine clinical use, and present an overview of innovative methods currently being explored.

Quantitative detection of melanoma-associated antigens by multimarker real-time RT-PCR for molecular staging: results of a 5 years study

INTRODUCTION

Monitoring of circulating melanoma cells in the peripheral blood is a promising method for identifying a subgroup of patients with minimal residual disease.

OBJECTIVES

To evaluate the prognostic impact of melanoma-associated antigens by multimarker real-time RT-PCR for disease-specific survival time.

METHODS

Five melanoma markers: Melan-A, gp 100, MAGE-3, MIA and tyrosinase were detected by a quantitative multimarker real-time reverse transcription-PCR (RT-PCR). We included 65 patients with resected melanoma in stage II-III. Peripheral blood samples were examined every 3 months for 2 years. The expression of melanoma markers in 2925 RT-PCR assays was correlated with clinical staging results in total of 5 years.

RESULTS

Twenty-seven patients relapsed during the study period and 26 of them revealed positive markers. MAGE-3 was the most sensitive progression marker in single occurrence or in combination with MIA and gp 100. The time distribution of metastases during the screened period was as follows: progression in the first year was observed in 40.7% patients, second year in 25.9%, third year in 18.6%, fourth and fifth year in 7.4% equally.

CONCLUSIONS

Statistically significant tumor marker elevation during the first 2 years after the surgical treatment correlates with a worse prognosis of patients. In contrast, the group showing negative real-time RT-PCR results in 24 months serial blood testing was associated with prolonged 5-year disease-specific survival. Therefore, quantitative detection of melanoma-specific molecular markers in the presented setting represents a useful tool for selecting patients in a higher risk of disease recurrence.

Early detection of melanoma progression by quantitative real-time RT-PCR analysis for multiple melanoma markers

Standard screening of melanoma patients is a useful tool for predicting outcome of patients, however, an instant methodology for exact detection of subclinical disease or monitoring treatment response is under investigation. Detection of circulating melanoma cells is, therefore, a possible novel promising staging method. However, inconsistent data on method sensitivity and on the predicted patient outcome has been shown repeatedly. Recently, a multimarker real-time RT-PCR methodology for quantification of five melanoma markers Melan-A, gp 100, MAGE-3, MIA and tyrosinase was described by our group. In the current prospective trial, blood specimens of 65 patients with AJCC stage IIB-III cutaneous melanoma after surgery were periodically examined. In the above group, 27 % of subjects relapsed during the study. Prior to the disease progression we could observe a statistically significant tumor marker elevation in previous 0 to 9 months in all patients with clinical relapse. MAGE-3 became the most sensitive progression marker. During progression, three concordant positive markers were seen in 39 % of patients, followed by two concordant positive markers in 28 % and 1 marker in 33 %. This study supports the use of a multimarker real-time RT-PCR as a disease progression predictor. The dynamic assessment of serially obtained blood specimens represents a useful method for early metastasis detection and treatment response of melanoma patients.

Multimarker real-time reverse transcription-PCR for quantitative detection of melanoma-associated antigens: a novel possible staging method

BACKGROUND

Detection of melanoma cells in peripheral blood is a promising method for monitoring haematogenous spread of melanoma cells. It enables us to detect early metastasis and to better stratify candidates for adjuvant immunotherapy. Inconsistent data on the sensitivity and clinical relevance of this method have been reported.

STUDY DESIGN

We developed a multimarker real-time reverse transcription-PCR (RT-PCR) for quantification of five melanoma markers: Melan-A, gp100, MAGE-3, MIA and tyrosinase. In this prospective study, 65 patients with resected cutaneous melanoma stage IIB-III were screened. Peripheral blood samples were collected every 3 months for the following 18 months, and circulating melanoma cells were examined and compared with clinical staging results.

RESULTS

Eighteen patients relapsed during the trial and showed different types of melanoma progression. All these patients experienced statistically significant tumour marker elevation in the period from 0 to 9 months before the disease progression. MAGE-3 was the most sensitive progression marker. In patients with progression, we observed three concordant positive markers in 39% of cases, two concordant positive markers in 28%, and finally one marker in 33%.

CONCLUSIONS

This report describes a multiple-marker real-time RT-PCR, which is able to provide quantitative data on melanoma markers in the peripheral blood of melanoma patients. Measurement of the studied molecular markers in our hands represents a prognostic factor and a useful method for early detection of metastasis and treatment response of melanoma patients.

Multiple splice variants within the bovine silver homologue (SILV) gene affecting coat color in cattle indicate a function additional to fibril formation in melanophores

Background

The silver homologue(SILV) gene plays a major role in melanosome development. SILV is a target for studies concerning melanoma diagnostics and therapy in humans as well as on skin and coat color pigmentation in many species ranging from zebra fish to mammals. However, the precise functional cellular mechanisms, in which SILV is involved, are still not completely understood. While there are many studies addressing SILV function upon a eumelaneic pigment background, there is a substantial lack of information regarding the further relevance of SILV, e.g. for phaeomelanosome development.

Results

In contrast to previous results in other species reporting SILV expression exclusively in pigmented tissues, our experiments provide evidence that the bovine SILV gene is expressed in a variety of tissues independent of pigmentation. Our data show that the bovine SILV gene generates an unexpectedly large number of different transcripts occurring in skin as well as in non-pigmented tissues, e.g. liver or mammary gland. The alternative splice sites are generated by internal splicing and primarily remove complete exons. Alternative splicing predominantly affects the repeat domain of the protein, which has a functional key role in fibril formation during eumelanosome development.

Conclusion

The expression of the bovine SILV gene independent of pigmentation suggests SILV functions exceeding melanosome development in cattle. This hypothesis is further supported by transcript variants lacking functional key elements of the SILV protein relevant for eumelanosome development. Thus, the bovine SILV gene can serve as a model for the investigation of the putative additional functions of SILV. Furthermore, the splice variants of the bovine SILV gene represent a comprehensive natural model to refine the knowledge about functional domains in the SILV protein. Our study exemplifies that the extent of alternative splicing is presumably much higher than previously estimated and that alternatively spliced transcripts presumably can generate molecules of deviating function compared to their constitutive counterpart.

The prognostic value of circulating tumor cells in patients with melanoma: a systematic review and meta-analysis

BACKGROUND

The detection of circulating tumor cells (CTC) in patients with melanoma represents an appealing prognostic tool, but no consensus exists on this topic. We aimed to comprehensively and quantitatively summarize the evidence for the use of CTC to predict patients' clinical outcome.

METHODS

Fifty-three studies enrolling 5,433 patients were reviewed. Correlation of CTC status with tumor-node-metastasis disease stage and patients' overall (OS) and progression-free (PFS) survival was assessed by means of association statistics and meta-analysis, respectively.

RESULTS

CTC status correlated with both tumor-node-metastasis stage (stage I, 32%; stage II, 41.7%; stage III, 41.1%; stage IV, 47.4%; P(trend) < 0.0001) and survival (OS: hazard ratio, 2.42; 95% confidence interval, 1.7-3.45, P < 0.0001; PFS: hazard ratio, 2.45; 95% confidence interval, 1.78-3.38; P < 0.0001). However, statistical heterogeneity was significant for both OS and PFS, likely underscoring the wide variability in study design. Furthermore, CTC positivity rates in early stages were higher and in the metastatic setting were lower than expected, which indicates an unsatisfactory accuracy of currently available CTC detection assays.

CONCLUSIONS

Our findings suggest that CTC might have a clinically valuable prognostic power in patients with melanoma. However, the heterogeneity of the studies thus far published warrants caution not to overestimate the favorable results of pooled data.

Quantitative detection of circulating tumor cells in cutaneous and ocular melanoma and quality assessment by real-time reverse transcriptase-polymerase chain reaction

PURPOSE

Inconsistent reports on the detection of melanoma cells in peripheral blood by reverse transcriptase-PCR (RT-PCR) have resulted in uncertainty on the prognostic value of circulating melanoma cells.

EXPERIMENTAL DESIGN

We developed real-time RT-PCR assays for quantitation of tyrosinase, MelanA/MART1, and gp100 and for porphobilinogen deaminase housekeeping gene. Melanoma tissue (n = 18), peripheral blood samples from healthy donors (n = 21), and patients with cutaneous (n = 122) and uveal (n = 64) melanoma from our institution were analyzed. For quality control, an additional 251 samples from ongoing multicenter studies were compared with in-house samples.

RESULTS

Tyrosinase was not detected in healthy donor blood samples. For the two other markers, cutoff values had to be defined to distinct patient samples from controls. Patients with stage IV uveal and cutaneous melanoma expressed all three markers more frequently and at higher levels in peripheral blood as compared with earlier stages. The variation of expression was 4 logs and correlated with tumor load and serum lactate dehydrogenase. In 2 of 3 uveal melanoma patients, detection of circulating tumor cells preceded the development of liver metastases. The diagnostic sensitivity was optimal in blood samples containing >0.1pg/ microl porphobilinogen deaminase (95.7% of in-house samples and 57.4% of multicenter samples).

CONCLUSIONS

Real-time RT-PCR is able to quantitatively define the quality of a sample and provides quantitative data for melanoma markers. Disparities in the results of previous studies may be attributable to undetected differences in sample quality. The prognostic relevance of this assay is currently under evaluation in several prospective randomized trials.

Detection of tyrosinase and tyrosinase-related protein 1 sequences from peripheral blood of melanoma patients using reverse transcription-polymerase chain reaction

BACKGROUND

malignant melanoma has one of the highest rates of metastasis. Unlike other solid cancers, no sensitive tumor markers or laboratory tests that can provide information of the risk of metastasis and predict the prognosis have yet been established.

OBJECTIVE

the study was done to establish a RT-PCR sensitive and specific enough to detect melanocyte-specific transcripts from peripheral blood cells.

METHODS

peripheral white blood cells were collected from 30 healthy donors and 43 melanoma patients. Melanocyte-specific tyrosinase (TYR) and tyrosinase-related protein 1 (TYRP1) were selected as targets of RT-PCR. The sensitivity of detection using SK-mel-23 melanoma cells and rates of false-positiveness using non-melanoma blood were compared between single-step PCR and nested PCR. Analysis of melanoma blood samples was carried out by the single-step PCR.

RESULTS

the nested RT-PCR amplified the TYR and TYRP1 sequences from 14 and 2 of the 30 healthy bloods, respectively. However, the single-step RT-PCR did not amplify TYR or TYRP1 sequences from any of the healthy controls. Our single-step RT-PCR detected 1.7 and 0.8 SK-mel-23 melanoma cells per ml blood for TYR and TYRP1, respectively. Overall, TYR mRNA was detected in 15 of the 43 melanoma patients (34.9%), and TYRP1 mRNA in 16 of the 43 (37.2%). The specificities of detection of TYR and TYRP1 were 83.3 and 88.9%, respectively.

CONCLUSION

our single-step RT-PCR for TYR and TYRP1 mRNAs is more specific than the previous nested RT-PCR for TYR and applicable to detect circulating melanoma cells.