Project description:Desmoid tumors are bland fibroblastic tumors with little histologic variation in different regions of the tumor. While desmoid tumors do not metastasize, they have a high rate of local recurrence after complete resection and no reliable predictors of clinical behavior exist. The presence of molecular intra- and inter-tumor heterogeneity has been well established in other, higher grade, sarcomas but little is known about molecular variability within histologically bland lesions. In this study, we sought to examine the extent of intra- and inter-tumoral clonal heterogeneity of desmoid tumors, which may contribute to their pathogenesis and possible relapse. We performed analysis of DNA methylation, DNA copy number alterations, point mutations and gene expression on 24 specimens from different areas from primary and recurrent desmoid tumors from 3 patients (7-9 specimens per patient). The studies showed a remarkable heterogeneity of DNA methylation, DNA copy number alterations, point mutations or gene expression in different regions in primary or recurrent tumors in each patient. We discovered the evidence for subclonal alterations in different areas of individual tumors. Among the four types of data, the transcriptomic profiles showed the highest degree of variability within tumors and between different tumors from the same patient. Gene expression signatures associated with favorable and unfavorable outcome were detected in different regions within the same tumor. This study shows an unexpected degree of intra- and inter-tumor heterogeneity in desmoid tumors. Our analysis indicates that even in this histologically monotonous lesion, molecular analysis of a single tumor biopsy may underestimate the magnitude of molecular alterations. We demonstrate that molecular intra- and inter-tumor heterogeneity is an important consideration in drug development and validation of prognostic and predictive biomarkers for these tumors.
Project description:Background: Epigenome-wide association studies (EWAS) have been widely applied to identify methylation CpG sites associated with human disease. To date, the Infinium Methylation EPIC array (EPIC) is commonly used for high-throughput DNA methylation profiling. However, the EPIC array covers only 30% of the human methylome. Methylation Capture bisulfite sequencing (MC-seq) captures target regions of methylome and has advantages of extensive coverage in the methylome at an affordable price. Methods: Epigenome-wide DNA methylation in four peripheral blood mononuclear cell samples was profiled by using SureSelectXT Methyl-Seq for MC-seq and EPIC platforms separately. CpG site-based reproducibility of MC-seq was assessed with DNA sample inputs ranging in quantity of high (> 1000ng), medium (300-1000ng), and low (150ng-300ng). To compare the performance of MC-seq and the EPIC arrays, we conducted a Pearson correlation and methylation value difference at each CpG site that was detected by both MC-seq and EPIC. We compared the percentage and counts in each CpG island and gene annotation between MC-seq and the EPIC array. Results: After quality control, an average of 3,708,550 CpG sites per sample was detected by MC-seq with DNA quantity >1000ng. Reproducibility of MC-seq detected CpG sites was high with strong correlation estimates for CpG methylation among samples with high, medium, and low DNA inputs (r > 0.96). The EPIC array captured an average of 846,464 CpG sites per sample. Compared with the EPIC array, MC-seq detected more CpGs in coding regions and CpG islands. Among the 472,540 CpG sites captured by both platforms, methylation of a majority of CpG sites was highly correlated in the same sample (r: 0.98~0.99). However, methylation for a small proportion of CpGs (N=235) differed significantly between the two platforms, with differences in beta values of greater than 0.5. Conclusions: Our results show that MC-seq is an efficient and reliable platform for methylome profiling with a broader coverage of the methylome than the array-based platform. Although methylation measurements in majority of CpGs are highly correlated, a number of CpG sites show large discrepancy between the two platforms, which warrants further investigation and needs cautious interpretation.
Project description:Background: Epigenome-wide association studies (EWAS) have been widely applied to identify methylation CpG sites associated with human disease. To date, the Infinium Methylation EPIC array (EPIC) is commonly used for high-throughput DNA methylation profiling. However, the EPIC array covers only 30% of the human methylome. Methylation Capture bisulfite sequencing (MC-seq) captures target regions of methylome and has advantages of extensive coverage in the methylome at an affordable price. Methods: Epigenome-wide DNA methylation in four peripheral blood mononuclear cell samples was profiled by using SureSelectXT Methyl-Seq for MC-seq and EPIC platforms separately. CpG site-based reproducibility of MC-seq was assessed with DNA sample inputs ranging in quantity of high (> 1000ng), medium (300-1000ng), and low (150ng-300ng). To compare the performance of MC-seq and the EPIC arrays, we conducted a Pearson correlation and methylation value difference at each CpG site that was detected by both MC-seq and EPIC. We compared the percentage and counts in each CpG island and gene annotation between MC-seq and the EPIC array. Results: After quality control, an average of 3,708,550 CpG sites per sample was detected by MC-seq with DNA quantity >1000ng. Reproducibility of MC-seq detected CpG sites was high with strong correlation estimates for CpG methylation among samples with high, medium, and low DNA inputs (r > 0.96). The EPIC array captured an average of 846,464 CpG sites per sample. Compared with the EPIC array, MC-seq detected more CpGs in coding regions and CpG islands. Among the 472,540 CpG sites captured by both platforms, methylation of a majority of CpG sites was highly correlated in the same sample (r: 0.98~0.99). However, methylation for a small proportion of CpGs (N=235) differed significantly between the two platforms, with differences in beta values of greater than 0.5. Conclusions: Our results show that MC-seq is an efficient and reliable platform for methylome profiling with a broader coverage of the methylome than the array-based platform. Although methylation measurements in majority of CpGs are highly correlated, a number of CpG sites show large discrepancy between the two platforms, which warrants further investigation and needs cautious interpretation.
Project description:Illumina Infinium HumanMethylation850 BeadChip (also known as Illumina EPIC array, GPL23976) was used to generate DNA methylation data from synthetic DNA from 3 species. The DNA samples from each species were enzymatically manipulated so that they would exhibit 0%, 25%, 50%, 75% and 100% percent methylation at each CpG location, respectively. The variable “ProportionMethylated” (with ordinal values 0, 0.25, 0.5, 0.75, 1) can be interpreted as a benchmark for each CpG that maps to the respective genome. Thus, the DNA methylation levels of each CpG are expected to have a high positive correlation with ProportionMethylated across the arrays measurement for the human species. The human EPIC array was applied to calibration data from mouse (n=15 EPIC arrays, 3 per methylation level) and rat (n=10, 2 per methylation level). The EPIC array data were normalized using the noob method (R function preprocessNoob in minfi).
Project description:We used the Illumina Infinium HumanMethylation EPIC beadchip array to profile 31 pediatric tumors with the histological diagnosis of anaplastic pilocytic astrocyoma (PA). PA with anaplasia has been defined in the 2016 WHO classification as a tumor with PA morphology and >4 mitoses per 10 HPF, with or without necrosis with a potential worse outcome. DNA Methylation based studies performed mainly in adults have put forward this subtype as a distinct entity. After performing the same techniques on pediatric samples, our findings argue that the diagnostic histomolecular criteria established for anaplasia in adult PA are not of diagnostic or prognostic value in a pediatric setting.
Project description:Desmoid tumors are bland fibroblastic tumors with little histologic variation in different regions of the tumor. While desmoid tumors do not metastasize, they have a high rate of local recurrence after complete resection and no reliable predictors of clinical behavior exist. The presence of molecular intra- and inter-tumor heterogeneity has been well established in other, higher grade, sarcomas but little is known about molecular variability within histologically bland lesions. In this study, we sought to examine the extent of intra- and inter-tumoral clonal heterogeneity of desmoid tumors, which may contribute to their pathogenesis and possible relapse. We performed analysis of DNA methylation, DNA copy number alterations, point mutations and gene expression on 24 specimens from different areas from primary and recurrent desmoid tumors from 3 patients (7-9 specimens per patient). The studies showed a remarkable heterogeneity of DNA methylation, DNA copy number alterations, point mutations or gene expression in different regions in primary or recurrent tumors in each patient. We discovered the evidence for subclonal alterations in different areas of individual tumors. Among the four types of data, the transcriptomic profiles showed the highest degree of variability within tumors and between different tumors from the same patient. Gene expression signatures associated with favorable and unfavorable outcome were detected in different regions within the same tumor. This study shows an unexpected degree of intra- and inter-tumor heterogeneity in desmoid tumors. Our analysis indicates that even in this histologically monotonous lesion, molecular analysis of a single tumor biopsy may underestimate the magnitude of molecular alterations. We demonstrate that molecular intra- and inter-tumor heterogeneity is an important consideration in drug development and validation of prognostic and predictive biomarkers for these tumors.
Project description:Desmoid tumors (also called deep or aggressive fibromatoses) are potentially life-threatening fibromatous lesions. Hereditary desmoid tumors arise in individuals affected by either familial adenomatous polyposis (FAP) or hereditary desmoid disease (HDD) carrying germline mutations in APC. Most non-FAP (sporadic) desmoids carry somatic mutations in the beta-catenin gene. Previous studies identified losses on 5q and 6q, and gains on 8q and 20q as recurrent genetic changes in desmoids. However, virtually all genetic changes were derived from sporadic tumors. To investigate the somatic alterations in FAP-associated desmoids and to compare them with changes occurring in sporadic tumors, we analyzed 17 FAP-associated and 38 sporadic desmoids for copy number abnormalities (CNAs) by means of array comparative genomic hybridization and multiple ligation-dependent probe amplification. Overall, the desmoids displayed only a limited number of genetic changes, occurring in 44% of cases. Common gains at 8q (7%) and 20q (5%) were almost exclusively found in sporadic tumors. Frequent common losses were observed within a 700 kb region at 5q22.2, comprising the APC gene (11%), in a 2 Mb region at 6p21.2-p21.1 (15%), and in a relatively large region at 6q15-q23.3 (20%). The FAP-associated desmoids displayed a significantly higher frequency of CNAs (59%) than the sporadic tumors (37%). As predicted by the APC germline mutations among these patients, a relatively high percentage (29%) of the FAP-associated desmoids showed loss of the APC region at 5q22.2, which was infrequently (3%) seen among sporadic tumors. Our data suggest that loss of region 6q15-q16.2 is an important event in FAP-associated as well as sporadic desmoids, most likely of relevance for desmoid tumor progression.
Project description:Infinium® HumanMethylation450 BeadChip and EPIC arrays were run with the aim of using the methylation profiles (n=986 in total) for sarcoma subtype classification (Paper: Lyskjær et al, 2021, DNA methylation-based profiling of bone and soft tissue tumours: a validation study of the ‘DKFZ sarcoma Classifier’ ). 500ng of DNA from fresh frozen (FT) or formalin-fixed paraffin-embedded (FFPE) tumour samples were bisulfite converted using the Zymo EZ DNA methylation Gold kit (Zymo Research Corp. Irvine, USA) before hybridisation to the Infinium HumanMethylation450 or EPIC beadchip arrays (Illumina, San Diego, CA) by UCL Genomics. All bisulfite-converted FFPE samples were restored with the Infinium FFPE DNA Restore kit (Illumina).