92 research outputs found
Genomic analysis of primary and metastatic malignant melanoma
No full text“Cutaneous melanoma is a most unpredictable lesion” wrote Alexander Breslow in 1970. He was one of the first to predict outcome in melanoma patients, based on the thickness of the primary tumor, and today this parameter bears his name and remains the main prognostic factor in melanoma. The aim of this thesis has been to contribute to the understanding of melanoma biology in order to make this cancer more “predictable”. This thesis consists of two parts. The first part addresses the question of progression of melanoma. By analysis of multiple metastatic tumors from the same patient we showed that, although multiple lesions contained a core of molecular aberrations, in most patients each metastasis carried additional individual events. This may illustrate the biological basis for the inherent therapy resistance of melanoma. The majority of the shared single base substitutions carried a signature of UV-induced DNA damage, providing evidence for causal involvement of UV radiation in melanomagenesis. However, the biology of individual metastases within a patient was often very different, as they belonged to different molecular subtypes with distinct gene expression patterns. In one patient, we observed a large number of non-UV mutations in a late stage metastasis, a phenomenon that was not observed in the lesions that had been diagnosed earlier. The second part of this thesis addresses the question of the biological diversity of melanoma. The “unpredictability” of melanoma is reflected by the occasional clinical observation of one or more metastases in patients with thin primary lesions, and cases of thick lesions that remain confined to the primary site. Therefore, additional factors influence prognosis, and these are included in the current staging system. We described gene-expression based grade as an independent prognostic factor in primary melanoma, and even in melanomas with Breslow thickness over 2 mm. High-grade tumors expressed increased levels of cell cycle and DNA damage response and repair genes, while low-grade was associated with elevated expression of immune-response genes. In conclusion, the findings presented in this thesis emphasize the heterogeneity of melanoma with clinical implications
The genetic evolution of melanoma
No full textMelanoma tumors are driven by a hyperactivated mitogen-activated protein kinase (MAPK) signalling pathway, and therefore can generally be classified by mutations within the B-Raf proto-oncogene (BRAF), RAS family of proto-oncogenes, neurofibromin 1 (NF1), or other genes. At the transcriptional level, several genetic classifications of melanoma have converged on the distinction between melanogenesis (previously microphthalmia) associated transcription factor (MITF)-low and MITF-high phenotypes and expression of immune-related genes. Mutation-based melanoma subtypes are not prognostic, nor are they associated to transcriptomic subtypes, which are in turn prognostic. Intratumoral heterogeneity of melanoma cells adds another layer of complexity, with recent findings of mutational and transcriptional heterogeneity within melanoma tumors. Furthermore, multiple genetic changes have been associated with different stages of melanoma progression. Mutational signatures may also be differentiated at early and late stages of melanoma progression
Genomic analysis of primary and metastatic malignant melanoma
No full textPopular Abstract in Swedish Malignt melanom (även kallad melanom) är den farligaste formen av hudcancer. Dess incidens varierar från land till land och är den högsta i Australien, där 46.7 per 100,000 invånare drabbas årligen. I Sverige är melanom den sjätte vanligaste cancersjukdomen. Melanom har blivit allt vanligare under de senaste två decennierna. Om tumören upptäcks på ett tidigt, dvs. lokaliserat, stadium (s.k. primärt melanom), har patienten oftast en god prognos. Dock kan det vara svårt att känna igen melanom då det ofta liknar ett födelsemärke. Därför upptäcks en del av tumörer efter det att de har spridit sig till andra organ (s.k. metastatiskt melanom), och prognosen är försämrad. Fram till i fjol hade det inte funnits mediciner som bromsar sjukdomen. Tack vare den intensiva forskningen de senaste decennierna världen runt hade man i fjol godkänt två nya läkemedel som har effekt på spritt melanom. Det är dock inte alla som svarar på behandlingen, och hos många av dem som gör kommer sjukdomen tillbaka. Därför är det viktigt att förstå de biologiska processerna som styr tumörutvecklingen. Den här avhandlingen syftar till att bidra till förståelsen av melanombiologin. I den här avhandlingen beskrivs arbetet med att klassificera primära melanom med hjälp av molekylära metoder, huvudsakligen genuttrycksprofilering. Vi har upptäckt att primära melanom kan delas in i fyra biologiska undergrupper (även kallade subtyper). Dessa grundar sig på molekylär karakterisering av 223 primära tumörer som har samlats in på avdelningen för patologi vid Lunds universitet. Den första gruppens melanom har ett högt uttryck av immunresponsgener och kallas i enlighet med detta ”high-immune”. Dessa tumörer innehåller ofta T celler som invaderar tumören i ett mönster som tidigare har visat sig gynnsam från prognostisk synvinkel. Den andra har förutom immunresponsgener även ett högt uttryck av gener som normalt kännetecknar hudceller och kallas därför ”normal-like”. Melanom i dessa två grupper är tunnare, har mindre ulceration och mitoser, vilka är alla positiva prognostiska tecken. Den tredje gruppen har ett högt uttryck av gener som styr eller medverkar i celldelningen och kallas därför ”proliferative”. Slutligen, den fjärde gruppen har ett högt uttryck av celldelningsgener och därutöver pigmenterings- och DNA reparationsgener, och kallas därför ”pigmentation”. De fyra grupperna har signifikant olika prognos, med en bättre överlevnad i high-immune och normal-like subtyperna. Därför går det att med stor sannolikhet förutsäga prognos redan på ett tidigt stadium om man undersöker genuttryck i primärtumören. Eftersom high-immune och normal-like grupperna hade så lika biologi och prognos, la vi samman dessa till en ny grupp (s.k. low-grade) och de andra två grupperna till high-grade. Lodrät (s.k. Breslow) tjocklek - mätt från utsidan av tumören ner till de tumörceller som har invaderat djupast in i huden - är den främsta prognostiska faktorn i melanom. Viktigt är att grade har ett prognostiskt värde även om man justerar för sjukdomsstadium, som innehåller Breslow som en av främsta parametrar. Dessutom, bland de tjockare tumörerna (Breslow över 2 mm) är grade den enda parametern som delar in patienterna i två grupper med signifikant olika överlevnad. Spritt, eller metastatiskt melanom har dålig prognos. En intressant fråga är vad som händer på molekylär nivå när flera metastaser uppstår hos en patient med en primärtumör. Är dessa metastaser lika som (bokstavligen) kloner av varandra, eller har de enskilda genetiska förändringar? Vi använde oss av genetisk och epigenetisk analys av tumörernas hela genom, liksom mutationsanalys av utvalda gener. Det visade sig att metastaser som uppstår hos en patient har många gemensamma förändringar. Detta indikerar deras gemensamma ursprung. Mutationsmönster i metastaserna återspeglade effekt av UV strålning, som är en känd faktor i uppkomst av melanom. Hos de flesta av patienterna bar dock varje metastas på enskilda förändringar vad gäller promotormetylering, uttryck av enskilda gener, kopietalav DNA fragment och även mutationer. Hos den ena patienten var de tumörspecifika mutationerna i den sista metastasen av en så avvikande typ (dvs. annan typ än UV mönstret) att en ny mutagen inte kan uteslutas; möjligen inducerades de av den DNA-alkylerande behandling som patienten fått innan metastasen diagnostiserades. Sammanfattningsvis tyder dessa studier på att melanommetastaser hos en patient kan skilja sig mycket. Det kan förklara den varierande behandlingseffekten och kanske även den snabba uppkomsten av resistens vid målriktad terapi.“Cutaneous melanoma is a most unpredictable lesion” wrote Alexander Breslow in 1970. He was one of the first to predict outcome in melanoma patients, based on the thickness of the primary tumor, and today this parameter bears his name and remains the main prognostic factor in melanoma. The aim of this thesis has been to contribute to the understanding of melanoma biology in order to make this cancer more “predictable”. This thesis consists of two parts. The first part addresses the question of progression of melanoma. By analysis of multiple metastatic tumors from the same patient we showed that, although multiple lesions contained a core of molecular aberrations, in most patients each metastasis carried additional individual events. This may illustrate the biological basis for the inherent therapy resistance of melanoma. The majority of the shared single base substitutions carried a signature of UV-induced DNA damage, providing evidence for causal involvement of UV radiation in melanomagenesis. However, the biology of individual metastases within a patient was often very different, as they belonged to different molecular subtypes with distinct gene expression patterns. In one patient, we observed a large number of non-UV mutations in a late stage metastasis, a phenomenon that was not observed in the lesions that had been diagnosed earlier. The second part of this thesis addresses the question of the biological diversity of melanoma. The “unpredictability” of melanoma is reflected by the occasional clinical observation of one or more metastases in patients with thin primary lesions, and cases of thick lesions that remain confined to the primary site. Therefore, additional factors influence prognosis, and these are included in the current staging system. We described gene-expression based grade as an independent prognostic factor in primary melanoma, and even in melanomas with Breslow thickness over 2 mm. High-grade tumors expressed increased levels of cell cycle and DNA damage response and repair genes, while low-grade was associated with elevated expression of immune-response genes. In conclusion, the findings presented in this thesis emphasize the heterogeneity of melanoma with clinical implications
The genetic evolution of melanoma
No full textMelanoma tumors are driven by a hyperactivated mitogen-activated protein kinase (MAPK) signalling pathway, and therefore can generally be classified by mutations within the B-Raf proto-oncogene (BRAF), RAS family of proto-oncogenes, neurofibromin 1 (NF1), or other genes. At the transcriptional level, several genetic classifications of melanoma have converged on the distinction between melanogenesis (previously microphthalmia) associated transcription factor (MITF)-low and MITF-high phenotypes and expression of immune-related genes. Mutation-based melanoma subtypes are not prognostic, nor are they associated to transcriptomic subtypes, which are in turn prognostic. Intratumoral heterogeneity of melanoma cells adds another layer of complexity, with recent findings of mutational and transcriptional heterogeneity within melanoma tumors. Furthermore, multiple genetic changes have been associated with different stages of melanoma progression. Mutational signatures may also be differentiated at early and late stagesof melanoma progression
A Counsel's Guide to Examining and Preparing Witnesses in International Arbitration
No full textMastering the art of witness examination is essential in order to prevail in international arbitration. Lawyers acting as counsel in arbitration know that witness evidence stands out from the plethora of documentary evidence in terms of uniqueness and authenticity. A vivid, first-hand live account of the events in issue exerts a strong influence on the arbitrators, and a handful of memorable testimonies can outweigh an avalanche of documents. This book shows how such mastery in the art of witness examination is accomplished. In the majority of today's international arbitrations, witness examination is modeled around the common law practice of lawyer-led questioning. Arbitration practitioners are therefore more and more expected to take charge of the examination process. Drawing on the principles of the art of advocacy in the common law tradition, this persuasive and highly engaging book sets out, in great detail, the practical techniques applicable to the use of witnesses in arbitration. The author describes such elements of witness evidence as the following: • differences between common law and civil law systems in regard to taking witness evidence; • techniques for interviewing witnesses and preparing witness statements; • question techniques for direct examination and cross-examination; • methods for developing forceful cross-examinations; • the boundaries of witness preparation; • preparing the witness for direct examination and cross-examination; • psychological risks of witness preparation; • guidelines for witnesses during direct examination and cross-examination. All topics are illustrated by way of practical examples, which also serve as a pool of useful model phrases and expressions. Practical appendices include ready-to-adapt sample documents, such as a procedural questionnaire, procedural rules and a witness statement. The book will be particularly useful for arbitration practitioners who have had little exposure to the adversarial approach to evidence and who wish to learn the ropes of lawyer-led witness examination and preparation. However, any practitioner stands to gain from applying the book's practical guidance and the author's wise counsel
762 A combination of functional biomarkers improves identification of the tumor-specific reactive T cell repertoire
No full textSwedish CDKN2A mutation carriers do not present the atypical mole syndrome phenotype.
No full textPhenotypic characteristics were examined in melanoma-prone southern Swedish CDKN2A (p16-113insArg/p14ARF-128insSer) mutation families, in relation to the CDKN2A genotype, nevi, clinically atypical nevi (CAN) and melanoma. Individuals from eight melanoma-prone families, with index patients carrying the CDKN2A mutation, were offered skin examinations and genotyping (CDKN2A and MC1R). Ninety-three individuals above 18 years of age participated; 29 invasive melanomas in 16 patients were recorded, all in the 38 verified CDKN2A mutation carriers. Median age at diagnosis was 36 years. Several MC1R variants were observed. A significant correlation to CAN (P=0.01) and red hair colour (P=0.02) could be confirmed in melanoma patients. A positive mutation status (CDKN2A) was correlated to one or more CAN (P=0.007) but neither to blue eyes, red hair colour, heavy freckling nor high number of nevi. For mutation carriers, median total naevus count was 24 and interquartile range was 12-47 (mean 31); whereas for the whole cohort, median total naevus count was 12 and interquartile range was 5-25 (mean 22). No participant fulfilled the atypical mole syndrome phenotype criteria. Melanomas were diagnosed only in mutation carriers, and melanoma diagnosis was statistically correlated to the presence of one or more CAN and red hair colour, supporting the possible synergistic effect of a MC1R mutation on increased risk of melanoma in patients with a CDKN2A mutation. Family history, with verified tumour diagnoses, remains an important clinical tool for finding mutation carriers for referral to clinical geneticists and simultaneous presence of CAN in probable mutation carriers might strengthen this indication. The atypical mole syndrome phenotype was, however, not verified in the studied families and total naevus counts were low
Multiple metastases from cutaneous malignant melanoma patients may display heterogeneous genomic and epigenomic patterns.
No full textDisseminated melanoma is an aggressive disease with fatal outcome. Better understanding of the underlying biology is needed to find effective treatment. We applied microarray-based comparative genomic hybridization, gene expression and CpG island methylation analysis of primary tumors and multiple metastases from five melanoma patients with the aim of analyzing the molecular patterns of melanoma progression. Epigenetic profiling showed that the multiple metastases after a single primary melanoma share similar methylation patterns for many genes, although differences in methylation between the lesions were evident for several genes, example, PTEN, TFAP2C, and RARB. In addition, DNA copy number and global gene expression profiles of tumors from individual patients were highly similar, confirming common origin of metastases. Some of the identified genomic aberrations, for example, gain of chromosome 6p and loss of chromosomes 6q and 10, persisted during progression, indicating early changes highly important for melanoma development. Homozygous deletions at 3p26.1 and 6q23.2-q23.3 appeared in two consecutive metastases originating from the same primary tumor, respectively, in a mutually exclusive manner that provides evidence for two genetically different subclones. However, in another case, the similarity of the copy number aberrations in subsequent metastatic lesions suggests sequential metastatic development through the clonal evolution. These data are further corroborated by a switch in CDH1 and CDH2 expression between metastases from the same patient. In conclusion, our results provide evidence for different models of metastatic progression in melanoma
The clinical significance of BRAF and NRAS mutations in a clinic-based metastatic melanoma cohort.
No full textBRAF and NRAS mutations are frequently found in melanoma tumours and recently developed BRAF targeted therapies demonstrate significant clinical benefit
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