Change search
ReferencesLink to record
Permanent link

Direct link
Biomarker Discovery in Cutaneous Malignant Melanoma: A Study Based on Tissue Microarrays and Immunohistochemistry
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology. (The Human Protein Atlas Project)
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The incidence of cutaneous malignant melanoma has increased dramatically in Caucasians the last few decades, an increase that is partly explained by altered sun exposure habits. For the individual patient, with a localized disease, the tumor thickness of the excised lesion is the most important prognostic factor. However, there is a need to identify characteristics that can place patients in certain risk groups.

In this study, the protein expression of multiple proteins in malignant melanoma tumors was studied, with the aim of identifying potential new candidate biomarkers. Representative samples from melanoma tissues were assembled in a tissue microarray format and protein expression was detected using immunohistochemistry. Multiple cohorts were used and for a subset of proteins the expression was also analyzed in melanocytes in normal skin and in benign nevi. The immunohistochemical staining was evaluated manually and for part of the proteins also with an automated algorithm.

The protein expression of STX7 was described for the first time in tumors of the melanocytic lineage. Stronger expression of STX7 and SOX10 was seen in superficial spreading melanomas compared with nodular malignant melanomas. An inverse relationship between STX7 expression and T-stage was seen and between SOX10 expression and T-stage and Ki-67, respectively. In a population-based cohort the expression of MITF was analyzed and found to be associated with prognosis. Twenty-one potential biomarkers were analyzed using bioinformatics tools and a protein signature was identified which had a prognostic value independent of T-stage. The protein driving this signature was RBM3, a protein not previously described in malignant melanoma. Other markers included in the signature were MITF, SOX10 and Ki-67.

In conclusion, the protein expression of numerous potential biomarkers was extensively studied and a new prognostic protein panel was identified which can be of value for risk stratification.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2011. , 53 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 644
Keyword [en]
antibody-based proteomics, automated analysis, biomarker, immunohistochemistry, malignant melanoma, survival, tissue microarray
National Category
Cell and Molecular Biology Cell and Molecular Biology Cell and Molecular Biology
Research subject
Medical Science; Pathology
Identifiers
URN: urn:nbn:se:uu:diva-146436ISBN: 978-91-554-8007-3OAI: oai:DiVA.org:uu-146436DiVA: diva2:398248
Public defence
2011-04-02, Rudbecksalen, Rudbecklaboratoriet, Dag Hammarskjöldsv 20, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2011-03-11 Created: 2011-02-16 Last updated: 2011-05-04Bibliographically approved
List of papers
1. Selective expression of Syntaxin-7 protein in benign melanocytes and malignant melanoma
Open this publication in new window or tab >>Selective expression of Syntaxin-7 protein in benign melanocytes and malignant melanoma
Show others...
2009 (English)In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 8, no 4, 1639-1646 p.Article in journal (Refereed) Published
Abstract [en]

To search for proteins expressed in human melanocytes and melanoma, we employed an antibody-based proteomics strategy to screen for protein expression in tissue microarrays containing normal tissues, cancer tissues and cell lines. Syntaxin-7 (STX7) was identified as a novel protein, not previously characterized in cells of melanocytic lineage, displaying a cell type-specific protein expression pattern. In tumor tissues, STX7 was expressed in malignant melanoma and lymphoma. The protein was further characterized regarding subcellular localization, specificity, tissue distribution pattern and potential as a diagnostic and prognostic marker using cell lines and tissue microarrays containing normal skin, melanocytic nevi and primary and metastatic melanoma. STX7 was expressed in normal melanocytes, various benign melanocytic nevi, atypical nevi and malignant melanoma. Analysis in two independent melanoma cohorts demonstrated STX7 expression in nearly all investigated tumors, although at varying levels (>90% positive tumors). The expression level of STX7 protein was inversely correlated to tumor stage, suggesting that decreased expression of STX7 is associated with more aggressive tumors. In conclusion, we present protein profiling data for a novel protein showing high sensitivity and specificity for cells of the melanocytic lineage. The presented antibody-based proteomics approach can be used as an effective strategy to identify novel tumor markers and evaluate their potential clinical relevance.

Keyword
malignant melanoma, melanocytes, antibody proteomics, tissue microarray, Syntaxin-7
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-105503 (URN)10.1021/pr800745e (DOI)000264928200004 ()19173671 (PubMedID)
Available from: 2009-06-04 Created: 2009-06-04 Last updated: 2011-05-04Bibliographically approved
2. SOX10 expression in superficial spreading and nodular malignant melanomas
Open this publication in new window or tab >>SOX10 expression in superficial spreading and nodular malignant melanomas
Show others...
2010 (English)In: Melanoma research, ISSN 0960-8931, E-ISSN 1473-5636, Vol. 20, no 6, 468-478 p.Article in journal (Refereed) Published
Abstract [en]

SOX10 is a transcription factor expressed in nerve cells and melanocytes. The aim of this study was to investigate the protein expression pattern of SOX10 in malignant melanoma tumors and to analyze whether the results correlated with clinical parameters and the proliferation marker Ki-67. Furthermore, proliferation and migration were analyzed in three different cell lines employing SOX10 small interfering RNA-mediated silencing. Expression patterns were determined in 106 primary tumors and 39 metastases in addition to 16 normal skin samples and six benign nevi employing immunohistochemistry and tissue microarrays. The immunohistochemical staining was evaluated manually and with an automated algorithm. SOX10 was strongly expressed in the benign tissues, but for the malignant tumors superficial spreading melanomas stained stronger than nodular malignant melanomas (P=0.008). The staining intensity was also inversely correlated with T-stage (Spearman's ρ=-0.261, P=0.008). Overall survival and time to recurrence were significantly correlated with SOX10 intensity, but not in multivariate analysis including T-stage. With the automated algorithm there was an inverse correlation between the SOX10 staining intensity and the proliferation marker, Ki-67 (ρ=-0.173, P=0.02) and a significant difference in the intensity signal between the benign tissues, the primary tumors and the metastases where the metastases stained the weakest (P≤0.001). SOX10 downregulation resulted in variable effects on proliferation and migration rates in the melanoma cell lines. In conclusion, the SOX10 intensity level differed depending on the tissue studied and SOX10 might have a role in survival. No conclusion regarding the role of SOX10 for in-vitro proliferation and migration could be drawn.

Keyword
Immunohistochemistry, malignant melanoma, small interfering RNA, SOX10
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-133423 (URN)10.1097/CMR.0b013e3283403ccd (DOI)000283744100005 ()20890226 (PubMedID)
Available from: 2010-11-10 Created: 2010-11-10 Last updated: 2011-05-04Bibliographically approved
3. MITF as a Prognostic Marker in Cutaneous Malignant Melanoma
Open this publication in new window or tab >>MITF as a Prognostic Marker in Cutaneous Malignant Melanoma
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Background: Microphthalmia associated transcription factor (MITF) protein has a central role in the differentiation and survival of melanocytes. The aim of the study was to investigate whether MITF can be employed as a prognostic marker in patients operated on for cutaneous malignant melanoma.

Methods: A cohort study design based on information collected from population-based registers. For included patients tissue microarrays and immunohistochemistry were employed to study the protein expression of MITF in the primary malignant melanoma tumors by estimating the fraction of positive tumor cells and the staining intensity.

Results: The vast majority of tumors expressed MITF in >25% of the tumor cells with a strong staining intensity and looking at these factors individually these patients had a better prognosis. When cell fraction and intensity were combined a high-risk group dying of malignant melanoma was identified as those with 25% -75% of tumor cells staining with weak intensity and those with <25% of tumor cells staining with strong intensity. However, the majority of the deaths occurred in the lower risk groups.

Conclusions: Although a high-risk group for death in malignant melanoma was identified we conclude that MITF is not useful as a prognostic marker because of the distribution of that particular expression in the population.

Impact: Our results indicate a bi-phasic pattern of MITF expression and although not useful as a prognostic marker these results are in line with other experimental studies and are relevant to explore further.

 

Keyword
MITF, prognosis, survival, immunohistochemistry, tissue microarray
National Category
Cell and Molecular Biology
Research subject
Cancer Epidemiology; Pathology
Identifiers
urn:nbn:se:uu:diva-143436 (URN)
Available from: 2011-02-16 Created: 2011-01-20 Last updated: 2011-05-04
4. Protein Biomarkers in Malignant Melanoma: An Image Analysis-Based Study on Melanoma Markers of Potential Clinical Relevance
Open this publication in new window or tab >>Protein Biomarkers in Malignant Melanoma: An Image Analysis-Based Study on Melanoma Markers of Potential Clinical Relevance
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The thickness of a primary malignant melanoma tumor is the most important prognostic indicator for a patient with primary cutaneous malignant melanoma. To optimize the management and treatment of melanoma patients there is an unmet need to identify characteristics that can further stratify melanoma patients into high or low risk for progressive disease. Despite numerous studies no single marker has yet been shown to add significant prognostic information. An algorithmic approach, combining data from several markers provides an attractive model to identify patients of increased risk of dying from malignant melanoma. The primary aim of the present study was to analyze the correlation between clinical outcome and protein expression patterns of multiple proteins in malignant melanoma tumors using immunohistochemistry and tissue microarrays. Candidate proteins were identified based on a selective and differential expression pattern in melanoma tumors and tested in a cohort of 143 melanoma patients. Protein expression was analyzed using both manual scoring and automated image analysis-based algorithms. We found no single marker of prognosis that was independent of tumor thickness. When combining potential prognostic markers we could define a prognostic index, based on RBM3, MITF, SOX10 and Ki-67, that was independent of tumor thickness in multivariate analysis. Our findings suggest that a good prognosis signature can be identified in melanoma patients with tumors showing a low fraction of Ki-67 positive tumor cells and a high fraction of RBM3 positive tumor cells combined with low intensity levels of SOX10 and MITF.

 

Keyword
malignant melanoma, immunohistochemistry, tissue microarray, protein expression, automated analysis, RBM3, SOX10, MITF, Ki-67
National Category
Cell and Molecular Biology
Research subject
Pathology; Bioinformatics
Identifiers
urn:nbn:se:uu:diva-144108 (URN)
Available from: 2011-02-16 Created: 2011-01-27 Last updated: 2011-05-04

Open Access in DiVA

fulltext(2265 kB)703 downloads
File information
File name FULLTEXT01.pdfFile size 2265 kBChecksum SHA-512
ae77848be5a8c14c27268f9177839b8196feea60ffd86dc0fd67e7e259f429398a8704ddd6b96cb582f2ba62d6dd4038c336cea2a82dc0301568643b88afef8b
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Agnarsdóttir, Margrét
By organisation
Department of Immunology, Genetics and Pathology
Cell and Molecular BiologyCell and Molecular BiologyCell and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar
Total: 703 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 526 hits
ReferencesLink to record
Permanent link

Direct link