| Literature DB >> 34470851 |
Weitao Lin1,2,3, Aaron B Beasley1,2, Nima Mesbah Ardakani4,5,6, Elena Denisenko3, Leslie Calapre2, Matthew Jones3, Benjamin A Wood4,5, Lydia Warburton1,2,7,8, Alistair R R Forrest3, Elin S Gray1,2.
Abstract
Tumor heterogeneity is a major obstacle to the success of cancer treatment. An accurate understanding and recognition of tumor heterogeneity is critical in the clinical management of cancer patients. Here, we utilized single-cell RNA sequencing (scRNA-seq) to uncover the intra- and intertumoral heterogeneity of liver metastases from a patient with metastatic uveal melanoma. The two metastases analyzed were largely infiltrated by noncancerous cells with significant variability in the proportion of different cell types. Analysis of copy-number variations (CNVs) showed gain of 8q and loss of 6q in both tumors, but loss of Chromosome 3 was only detected in one of the tumors. Single-nucleotide polymorphism (SNP) array revealed a uniparental isodisomy 3 in the tumor with two copies of Chromosome 3, indicating a regain of Chromosome 3 during the development of the metastatic disease. In addition, both tumors harbored subclones with additional CNVs. Pathway enrichment analysis of differentially expressed genes revealed that cancer cells in the metastasis with isodisomy 3 showed up-regulation in epithelial-mesenchymal transition and myogenesis related genes. In contrast, up-regulation in interferon signaling was observed in the metastasis with monosomy 3 and increased T-cell infiltrate. This study highlights the complexity and heterogeneity of different metastases within an individual case of uveal melanoma.Entities:
Keywords: choroidal melanoma
Mesh:
Year: 2021 PMID: 34470851 PMCID: PMC8559622 DOI: 10.1101/mcs.a006111
Source DB: PubMed Journal: Cold Spring Harb Mol Case Stud ISSN: 2373-2873
Figure 1.The patient's clinical information. (A) Treatment history of the patient. (B) An intensely 18F-fluorodeoxyglucose (FDG)-avid liver lesion (white arrows) was identified in the left lateral segment by positron emission tomography (PET) in week 246. The total lesion glycolysis was equal to 84 standardized uptake value (SUV) × cm3. (C) Hemotoxylin and eosin (H&E) staining of two liver metastases WL02 and WL03. Tumor cells in WL02 (left) had a spindled to epithelioid appearance with a relatively high number of admixed stromal cells in an oedematous stroma, whereas tumor cells in WL03 (right) had an epithelioid appearance and the stroma was rich in lymphocytes at the periphery of the tumor (H&E, original magnification, both ×350). (UM) Uveal melanoma, (MLPA) multiplex litigation-dependent probe amplification, (scRNA-seq) single-cell RNA sequencing, (WGS) whole-genome sequencing, (aCGH) array comparative genomic hybridization.
Figure 2.Aggregate analysis of 6341 single cells from two liver metastases. (A) Uniform manifold approximation and projection (UMAP) plot of 6341 single cells, colored by cell types that were manually assigned to cell clusters. (B) Pie chart of each liver metastasis showing the percentages of annotated cell types. (C) Cell cycle distribution of tumor cells. Percentage of tumor cells in different phases of the cell cycle was estimated in WL02 (left) and WL03 (right) using CellCycleScoring function in Seurat. (D) Gene set enrichment analysis (GSEA) pathways enriched by differentially expressed genes of tumor cells. Differentially enriched biological pathways are displayed ordered by the normalized enrichment score (NES). (DC) Plasmacytoid dendritic cell, (NK) natural killer, (HSC) hematopoietic stem cell.
Figure 3.Copy-number variation (CNV) analysis of two liver metastases. (A) Hierarchical clustering from inferCNV analysis showing CNV changes by chromosomes (columns) for individual tumor cells (rows). Blue indicates copy gains and red indicates copy losses. (B) Low-pass whole-genome sequencing (LP-WGS) analysis of two liver metastases. CNVs are denoted by horizontal lines indicating total or partial chromosomal losses (red) or gains (blue). (C) Clonality trees of each of tumor cells in the two liver metastases. The branches are scaled according to percentage of cells in the calculated subclone containing the indicated CNVs. (D) Single-nucleotide polymorphism (SNP) array-based karyotyping of WL02. (Chr) Chromosome.
Figure 4.Analysis of gene expression in two liver metastases. (A) Immunohistochemical staining with BAP1 antibody in WL02; note the loss of nuclear staining in tumor cells (arrow) in the presence of positive internal control (retained nuclear staining) in endothelial and stromal cells (asterisk) (BAP-1 IHC, original magnification ×320). (B) Ridge plots of the 15-gene panel in tumor cells between WL02 and WL03. Red arrows indicate the direction of change in a Class 2 tumor.