Project description:Melanoma recurrence frequently occurs after a latency period of several years. In vivo studies demonstrated that tumor cells overcoming latency show a T cell-edited phenotype, suggesting a relevant role for CD8+ T cells in maintaining metastatic latency. Here, in a patient model of multiple recurrent lesions, we illustrate the genetic evolution of poorly immunogenic melanoma phenotypes, evolving in the presence of autologous tumor antigen-specific CD8+ T cells. Melanoma cells from two of three late recurrent metastases, developing within a 6-year latency period, lacked HLA class I expression. HLA class I-negative tumor cells became clinically apparent 1.5 and 6 years into stage IV disease. Genome profiling by SNP arrays revealed total T-cell resistance in both metastases originating from a shared chromosome 15q alteration and independently acquired focal B2M gene deletions. A third HLA class I-positive lesion developed in year 3 of stage IV disease. By HLA haplotype loss lesion-derived melanoma cells acquired resistance towards dominant T-cell clonotypes targeting early stage III tumor cells. Early disease melanoma cells showed a dedifferentiated MITFnegative phenotype, recently described to be associated with immunosuppression, in contrast to the MITFhigh phenotype of T cell-edited tumor cells from late metastases. In summary, our study demonstrates that tumor recurrences after long-term latency develop towards T-cell resistance by independent genetic events, suggesting a mechanism of T cell-driven genetic evolution of melanoma as a means to evade immune recognition and tumor immunotherapy. Genetic alterations lead to loss of tumor antigen presentation.
Project description:Melanoma recurrence frequently occurs after a latency period of several years. In vivo studies demonstrated that tumor cells overcoming latency show a T cell-edited phenotype, suggesting a relevant role for CD8+ T cells in maintaining metastatic latency. Here, in a patient model of multiple recurrent lesions, we illustrate the genetic evolution of poorly immunogenic melanoma phenotypes, evolving in the presence of autologous tumor antigen-specific CD8+ T cells. Melanoma cells from two of three late recurrent metastases, developing within a 6-year latency period, lacked HLA class I expression. HLA class I-negative tumor cells became clinically apparent 1.5 and 6 years into stage IV disease. Genome profiling by SNP arrays revealed total T-cell resistance in both metastases originating from a shared chromosome 15q alteration and independently acquired focal B2M gene deletions. A third HLA class I-positive lesion developed in year 3 of stage IV disease. By HLA haplotype loss lesion-derived melanoma cells acquired resistance towards dominant T-cell clonotypes targeting early stage III tumor cells. Early disease melanoma cells showed a dedifferentiated MITFnegative phenotype, recently described to be associated with immunosuppression, in contrast to the MITFhigh phenotype of T cell-edited tumor cells from late metastases. In summary, our study demonstrates that tumor recurrences after long-term latency develop towards T-cell resistance by independent genetic events, suggesting a mechanism of T cell-driven genetic evolution of melanoma as a means to evade immune recognition and tumor immunotherapy. Genetic alterations lead to loss of tumor antigen presentation. Cell lines were generated from tumor material, differences in T cell recognition were observed and Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from the cell lines. SNP analysis of different melanoma cell lines obtained from one melanoma patient (4 cell lines from different metastasis of one patient with matching germline DNA).
Project description:SNP arrays were used to derive copy number estimates and identify amplifications and deletions in melanomas These copy number breakpoints were compared to gene fusions identified by second generation sequencing of cDNA
Project description:Comparison between the copy number of differentially methylated sites between lymph node metastasis from melanoma patients with good prognosis and melanoma brain metastasis. All samples are taken from different patients, and were established as cell lines in the John Wayne Cancer Institute.
Project description:DNA from resected colon cancer primary tumour tissue was analyzed for association between tumour dissemination and copy number alterations.
Project description:Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from fresh frozen tissues. To obtain a profile of copy number alterations in RMS, we studied 65 samples in 60 RMS cases. Other data of 38 samples are deposited in GSE41263: GSM1528059 GSM1528057 GSM1528061 GSM1528058 GSM1528054 GSM1528060 GSM1012723 GSM1012722 GSM1012746 GSM1528055 GSM1528056 GSM1530028 GSM1012751 GSM1012724 GSM1012726 GSM1012747 GSM1012725 GSM1012716 GSM1012735 GSM1012713 GSM1012736 GSM1012737 GSM1012738 GSM1012730 GSM1012739 GSM1012740 GSM1012750 GSM1012717 GSM1012718 GSM1012719 GSM1012741 GSM1012732 GSM1012715 GSM1012720 GSM1012742 GSM1012721 GSM1012743 GSM1012744
Project description:Allele call files from on 250K StyI SNP array using DNA from 60 human cell lines from metastasized melanoma and from 44 corresponding peripheral blood mononuclear cells (CEL and CHP files provided).
Project description:Ibrutinib (Ibr), an orally administered covalent inhibitor of Bruton’s kinase, has generated remarkable responses in CLL patients including those with an unfavorable cytogenetic profile. Once patients develop resistance to ibrutinib, the outcome is poor with few treatment options. To further understand the genomic mechanisms underlying Ibr resistance, we’ve performed genome wide copy number analysis of serial samples collected from nine ibrutinib-relapsed patients. Deletions of 18p often coincide with del(17p)/TP53 mutations, predispose patients to relapse.