NestedBD: Bayesian inference of phylogenetic trees from single-cell copy number profiles under a birth-death model

Copy number aberrations (CNAs) are ubiquitous in many types of cancer. Inferring CNAs from cancer genomic data could help shed light on the initiation, progression, and potential treatment of cancer. While such data have traditionally been available via "bulk sequencing," the more recently introduced techniques for single-cell DNA sequencing (scDNAseq) provide the type of data that makes CNA inference possible at the single-cell resolution. We introduce a new birth-death evolutionary model of CNAs and a Bayesian method, NestedBD, for the inference of evolutionary trees (topologies and branch lengths with relative mutation rates) from single-cell data. We evaluated NestedBD's performance using simulated data sets, benchmarking its accuracy against traditional phylogenetic tools as well as state-of-the-art methods. The results show that NestedBD infers more accurate topologies and branch lengths, and that the birth-death model can improve the accuracy of copy number estimation. And when applied to biological data sets, NestedBD infers plausible evolutionary histories of two colorectal cancer samples. NestedBD is available at https://github.com/Androstane/NestedBD .

Whole-genome sequencing as an alternative to analyze copy number abnormalities in acute myeloid leukemia and myelodysplastic syndrome

Copy number aberrations (CNA) are the core determinants for diagnosis, risk stratification and prognosis in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). In this study, a shallow whole-genome sequencing-based assay, LeukoPrint, was utilized to depict genomic CNA profiles from the bone marrow of 137 newly diagnosed AML/MDS patients. It demonstrated 98.1% concordance of CNA profiles with cytogenetics and/or fluorescence in situ hybridization (FISH). It is advantageous in detecting CNAs of short segments (1 Mb) and from samples with low leukemic cell content, more accurate for describing complex karyotypes and less confounded by subjective bias. LeukoPrint improved the overall diagnostic yield by redefining the risk categories for 16 patients by presenting new information. In summary, LeukoPrint provided an automated, convenient, and cost-effective approach to describe genomic CNA profiles. It brought greater diagnostic yield and risk stratification information by incorporating into the routine cytogenetics based on the CNA-related criteria of standard ELN/IPSS-R guidelines.

The feasibility of using liquid biopsies as a complementary assay for copy number aberration profiling in routinely collected paediatric cancer patient samples

BACKGROUND

Paediatric tumours are often characterised by the presence of recurrent DNA copy number alterations (CNAs). These DNA copy number profiles, obtained from a tissue biopsy, can aid in the correct prognostic classification and therapeutic stratification of several paediatric cancer entities (e.g. MYCN amplification in neuroblastoma) and are part of the routine diagnostic practice. Liquid biopsies (LQBs) offer a potentially safer alternative for such invasive tumour tissue biopsies and can provide deeper insight into tumour heterogeneity.

PROCEDURE

The robustness and reliability of LQB CNA analyses was evaluated. We performed retrospective CNA profiling using shallow whole-genome sequencing (sWGS) on paired plasma circulating cell-free DNA (cfDNA) and tissue DNA samples from routinely collected samples from paediatric patients (n = 128) representing different tumour entities, including osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, Wilms tumour, brain tumours and neuroblastoma.

RESULTS

Overall, we observed a good concordance between CNAs in tissue DNA and cfDNA. The main cause of CNA discordance was found to be low cfDNA sample quality (i.e. the ratio of cfDNA (<700 bp) and high molecular weight DNA (>700 bp)). Furthermore, CNAs were observed that were present in cfDNA and not in tissue DNA, or vice-versa. In neuroblastoma samples, no false-positives or false-negatives were identified for the detection of the prognostic marker MYCN amplification.

CONCLUSION

In future prospective studies, CNA analysis on LQBs that are of sufficient quality can serve as a complementary assay for CNA analysis on tissue biopsies, as either cfDNA or tissue DNA can contain CNAs that cannot be identified in the other biomaterial.

Identification of the immune gene expression signature associated with recurrence of high-grade gliomas

High-grade gliomas (HGGs), the most common and aggressive primary brain tumors in adults, inevitably recur due to incomplete surgery or resistance to therapy. Intratumoral genomic and cellular heterogeneity of HGGs contributes to therapeutic resistance, recurrence, and poor clinical outcomes. Transcriptomic profiles of HGGs at recurrence have not been investigated in detail. Using targeted sequencing of cancer-related genes and transcriptomics, we identified single nucleotide variations, small insertions and deletions, copy number aberrations (CNAs), as well as gene expression changes and pathway deregulation in 16 pairs of primary and recurrent HGGs. Most of the somatic mutations identified in primary HGGs were not detected after relapse, suggesting a subclone substitution during the tumor progression. We found a novel frameshift insertion in the ZNF384 gene which may contribute to extracellular matrix remodeling. An inverse correlation of focal CNAs in EGFR and PTEN genes was detected. Transcriptomic analysis revealed downregulation of genes involved in messenger RNA splicing, cell cycle, and DNA repair, while genes related to interferon signaling and phosphatidylinositol (PI) metabolism are upregulated in secondary HGGs when compared to primary HGGs. In silico analysis of the tumor microenvironment identified M2 macrophages and immature dendritic cells as enriched in recurrent HGGs, suggesting a prominent immunosuppressive signature. Accumulation of those cells in recurrent HGGs was validated by immunostaining. Our findings point to a substantial transcriptomic deregulation and a pronounced infiltration of immature dendritic cells in recurrent HGG, which may impact the effectiveness of frontline immunotherapies in the GBM management. KEY MESSAGES: Most of the somatic mutations identified in primary HGGs were not detected after relapse. Focal CNAs in EGFR and PTEN genes are inversely correlated in primary and recurrent HGGs. Transcriptomic changes and distinct immune-related signatures characterize HGG recurrence. Recurrent HGGs are characterized by a prominent infiltration of immature dendritic and M2 macrophages.

Methods for copy number aberration detection from single-cell DNA-sequencing data

Copy number aberrations (CNAs), which are pathogenic copy number variations (CNVs), play an important role in the initiation and progression of cancer. Single-cell DNA-sequencing (scDNAseq) technologies produce data that is ideal for inferring CNAs. In this review, we review eight methods that have been developed for detecting CNAs in scDNAseq data, and categorize them according to the steps of a seven-step pipeline that they employ. Furthermore, we review models and methods for evolutionary analyses of CNAs from scDNAseq data and highlight advances and future research directions for computational methods for CNA detection from scDNAseq data.

Molecular comparison of pure ovarian fibroma with serous benign ovarian tumours

OBJECTIVE

Ovarian fibromas and adenofibromas are rare ovarian tumours. They are benign tumours composed of spindle-like stromal cells (pure fibroma) or a mixture of fibroblast and epithelial components (adenofibroma). We have previously shown that 40% of benign serous ovarian tumours are likely primary fibromas due to the neoplastic alterations being restricted to the stromal compartment of these tumours. We further explore this finding by comparing benign serous tumours to pure fibromas.

RESULTS

Performing copy number aberration (CNA) analysis on the stromal component of 45 benign serous tumours and 8 pure fibromas, we have again shown that trisomy of chromosome 12 is the most common aberration in ovarian fibromas. CNAs were more frequent in the pure fibromas than the benign serous tumours (88% vs 33%), however pure fibromas more frequently harboured more than one CNA event compared with benign serous tumours. As these extra CNA events observed in the pure fibromas were unique to this subset our data indicates a unique tumour evolution. Gene expression analysis on the two cohorts was unable to show gene expression changes that differed based on tumour subtype. Exome analysis did not reveal any recurrently mutated genes.

Rare myeloid sarcoma with KMT2A (MLL)-ELL fusion presenting as a vaginal wall mass

Backgroud

Myeloid sarcoma (MS) is a rare neoplasm of immature myeloid precursors that form tumor mass outside the bone marrow. The diagnosis of de novo MS can be challenging, particularly in patients with no prior history of hematologic malignancies or when MS involves unusual anatomic sites.

Case presentation

The patient was a 53-year-old woman with a history of uterine fibroids and vaginal bleeding for many years who presented with a vaginal wall mass. The tumor had histologic and phenotypic features of histiocytic sarcoma, however, overlapping with a possible extramedullary MS. Using a comprehensive genomic profiling, we were able to identify recurrent chromosomal aberrations associated with MS including a rare KMT2A-ELL fusion, losses of chromosomes 1p, 9, 10, 15, 18, and gain of chromosome 1q and mutations in FLT3 and PTPN11, and achived the final diagnosis of a de novo MS. The patient received standard treatment for acute myeloid leukemia regimen with stem cell transplantation and achieved complete remission.

Conclusion

Our case illustrates the clinical utility of comprehensive genomic profiling in assisting the diagnosis or differential diagnosis of challenging MS or histiocytic sarcoma cases, and in providing important information in tumor biology for appropriate clinical management.

Molecular testing of borderline cutaneous melanocytic lesions: SNP array is more sensitive and specific than FISH

Melanocytic lesions with borderline features are diagnostically challenging. Single-nucleotide polymorphism (SNP) arrays, which detect genomic copy number alterations (CNAs), can be helpful in distinguishing between nevi and melanoma. Fluorescence in situ hybridization (FISH) has been used as a more rapid, less expensive alternative to SNP array, using a panel of probes that are often gained or lost in melanoma. We used SNP array data from 63 borderline cutaneous melanocytic lesions and 44 definitive melanomas to predict the performance of FISH testing. Lesions were considered positive by "virtual FISH" if 1 or more of the 5 FISH-probed loci demonstrated appropriate CNAs by SNP array. Cases were classified as positive by SNP array if ≥3 CNAs were present, based on internal validation studies, or if FISH criteria were met. Conventional FISH was performed in 33 cases (17 borderline lesions, 16 melanomas). Of the 63 borderline cases, 44 (70%) were positive by SNP array and 30 (48%) were positive by virtual FISH. A higher proportion of melanomas were positive by SNP array (41/44, 93% sensitivity) and virtual FISH (36/44, 82% sensitivity). Virtual FISH had 61% sensitivity in the borderline group using SNP array as the gold standard, whereas specificity was 84%. There was good correlation between conventional and virtual FISH, with agreement in 30 of 33 (91%) cases. Although FISH is highly effective in distinguishing between nevi and melanoma in cases where the histological diagnosis is straightforward, it is not nearly as sensitive or specific as SNP array when applied to borderline lesions.

Assessing copy number aberrations and copy neutral loss of heterozygosity across the genome as best practice: An evidence based review of clinical utility from the cancer genomics consortium (CGC) working group for myelodysplastic syndrome, myelodysplastic/myeloproliferative and myeloproliferative neoplasms

Multiple studies have demonstrated the utility of chromosomal microarray (CMA) testing to identify clinically significant copy number alterations (CNAs) and copy-neutral loss-of-heterozygosity (CN-LOH) in myeloid malignancies. However, guidelines for integrating CMA as a standard practice for diagnostic evaluation, assessment of prognosis and predicting treatment response are still lacking. CMA has not been recommended for clinical work-up of myeloid malignancies by the WHO 2016 or the NCCN 2017 guidelines but is a suggested test by the European LeukaemiaNet 2013 for the diagnosis of primary myelodysplastic syndrome (MDS). The Cancer Genomics Consortium (CGC) Working Group for Myeloid Neoplasms systematically reviewed peer-reviewed literature to determine the power of CMA in (1) improving diagnostic yield, (2) refining risk stratification, and (3) providing additional genomic information to guide therapy. In this manuscript, we summarize the evidence base for the clinical utility of array testing in the workup of MDS, myelodysplastic/myeloproliferative neoplasms (MDS/MPN) and myeloproliferative neoplasms (MPN). This review provides a list of recurrent CNAs and CN-LOH noted in this disease spectrum and describes the clinical significance of the aberrations and how they complement gene mutation findings by sequencing. Furthermore, for new or suspected diagnosis of MDS or MPN, we present suggestions for integrating genomic testing methods (CMA and mutation testing by next generation sequencing) into the current standard-of-care clinical laboratory testing (karyotype, FISH, morphology, and flow).

Genetic profiles of different subsets of Merkel cell carcinoma show links between combined and pure MCPyV-negative tumors

Tumorigenesis in Merkel cell carcinoma (MCC) is driven by (1) clonal integration of the Merkel cell polyomavirus (MCPyV) in neoplastic cells and/or (2) genetic damage by ultraviolet (UV) light. A higher mutational burden, a UV-mutational signature, and many mutations in the TP53 and RB1 genes characterize the virus-negative subset. MCPyV-negative MCCs include combined (often squamous and neuroendocrine) and pure (neuroendocrine) tumors. Because a combined morphology could elude detection microscopically, we sought a genetic link between combined and pure virus-negative tumors. From a global cohort of 46 cases, 9 pure MCPyV-positive, 9 pure MCPyV-negative, and 10 combined MCPyV-negative MCCs were studied by genome-wide microarray in search of copy number aberrations. The entire cohort (n=46) was evaluated by next-generation sequencing for mutations in selected tumor suppressor genes and oncogenes. More copy number aberrations and a greater fraction of the genome were changed in combined and pure MCPyV-negative tumors relative to MCPyV-positive cases (P<.01 for all comparisons). No difference in these parameters was found between the 2 MCPyV-negative groups. Copy number loss of RB1 or an inactivating RB1 mutation (either or both) was common in combined (8/10, 80%) and pure (7/9, 78%) MCPyV-negative tumors but not MCPyV-positive cases (1/9, 11%). A similar trend was seen for TP53 (combined [2/10, 20%] and pure virus-negative tumors [5/9, 56%] showed gene copy number loss or mutations contrasted with pure virus-positive cases [0/9, 0%]). The shared genetic profiles of combined and pure MCPyV-negative tumors link these subsets and separate them from MCPyV-positive tumors.

Characterization of genome-wide copy number aberrations in colonic mixed adenoneuroendocrine carcinoma and neuroendocrine carcinoma reveals recurrent amplification of PTGER4 and MYC genes. Hum Pathol. 2018;73:16-25. [PMID: 28899736 DOI: 10.1016/j.humpath.2017.08.036]

Colonic mixed adenoneuroendocrine carcinoma (MANEC) is an aggressive neoplasm with worse prognosis compared with adenocarcinoma. To gain a better understanding of the molecular features of colonic MANEC, we characterized the genome-wide copy number aberrations of 14 MANECs and 5 neuroendocrine carcinomas using the OncoScan FFPE (Affymetrix, Santa Clara, CA) assay. Compared with 269 colonic adenocarcinomas, 19 of 42 chromosomal arms of MANEC exhibited a similar frequency of major aberrant events as adenocarcinomas, and 13 chromosomal arms exhibited a higher frequency of copy number gains. Among them, the most significant chromosomal arms were 5p (77% versus 13%, P = .000012) and 8q (85% versus 33%, P = .0018). The Genomic Identification of Significant Targets in Cancers algorithm identified 7 peaks that drive the tumorgenesis of MANEC. For all except 5p13.1, the peaks largely overlapped with those of adenocarcinoma. Two tumors exhibited MYC amplification localized in 8q24.21, and 2 tumors exhibited PTGER4 amplification localized in 5p13.1. A total of 8 tumors exhibited high copy number gain of PTGER4 and/or MYC. Whereas the frequency of MYC amplification was similar to adenocarcinoma (10.5% versus 4%, P = .2), the frequency of PTGER4 amplification was higher than adenocarcinoma (10.5% versus 0.3%, P = .01). Our study demonstrates similar, but also distinct, copy number aberrations in MANEC compared with adenocarcinoma and suggests an important role for the MYC pathway of colonic carcinoma with neuroendocrine differentiation. The discovery of recurrent PTGER4 amplification implies a potential of exploring targeting therapy to the prostaglandin synthesis pathways in a subset of these tumors.

Multi-omics of 34 colorectal cancer cell lines - a resource for biomedical studies

Background

Colorectal cancer (CRC) cell lines are widely used pre-clinical model systems. Comprehensive insights into their molecular characteristics may improve model selection for biomedical studies.

Methods

We have performed DNA, RNA and protein profiling of 34 cell lines, including (i) targeted deep sequencing (n = 612 genes) to detect single nucleotide variants and insertions/deletions; (ii) high resolution DNA copy number profiling; (iii) gene expression profiling at exon resolution; (iv) small RNA expression profiling by deep sequencing; and (v) protein expression analysis (n = 297 proteins) by reverse phase protein microarrays.

Results

The cell lines were stratified according to the key molecular subtypes of CRC and data were integrated at two or more levels by computational analyses. We confirm that the frequencies and patterns of DNA aberrations are associated with genomic instability phenotypes and that the cell lines recapitulate the genomic profiles of primary carcinomas. Intrinsic expression subgroups are distinct from genomic subtypes, but consistent at the gene-, microRNA- and protein-level and dominated by two distinct clusters; colon-like cell lines characterized by expression of gastro-intestinal differentiation markers and undifferentiated cell lines showing upregulation of epithelial-mesenchymal transition and TGFβ signatures. This sample split was concordant with the gene expression-based consensus molecular subtypes of primary tumors. Approximately ¼ of the genes had consistent regulation at the DNA copy number and gene expression level, while expression of gene-protein pairs in general was strongly correlated. Consistent high-level DNA copy number amplification and outlier gene- and protein- expression was found for several oncogenes in individual cell lines, including MYC and ERBB2.

Conclusions

This study expands the view of CRC cell lines as accurate molecular models of primary carcinomas, and we present integrated multi-level molecular data of 34 widely used cell lines in easily accessible formats, providing a resource for preclinical studies in CRC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0691-y) contains supplementary material, which is available to authorized users.

Application of high-resolution genomic profiling in the differential diagnosis of liposarcoma

Background

Rarity and heterogeneity of liposarcomas (LPS) make their diagnosis difficult even for sarcoma-experts pathologists. The molecular mechanism underlying the development and progression of liposarcomas (LPS) remains only partially known. In order to identify and compare the genomic profiles, we analyzed array-based comparative genomic hybridization (array-CGH) profiles of 66 liposarcomas, including well-differentiated (WDLPS), dedifferentiated (DDLPS) and myxoid (MLPS) subtypes.

Results

Copy number aberrations (CNAs) were identified in 98% of WDLPS and DDLPS and in 95% of MLPS cases. The minimal common region of amplification at 12q14.1q21.1 was observed in 96% of WDLPS and DDLPS cases. Four regions of CNAs, including losses of chromosome 6, 11 and 13 and gains of chromosome 14 were classified as recurrent in DDLPS; at least one was identified in 74% of DDLPS tumors. The DDLPS-associated losses were much more common in tumors with increased genomic complexity. In MLPS, the most frequent CNAs were losses of chromosome 6 (40%) and gains of chromosome 1 (30%), with the minimal overlapping regions 6q14.1q22.31 and 1q25.1q32.2, respectively.

Conclusions

Our findings show that the application of array-CGH allows to delineate clearly the genomic profiles of WDLPS, DDLPS and MLPS that reflect biological differences between these tumors. Although CNAs varied widely, the subtypes of tumors have characteristic genomic profiles that could facilitate the differential diagnosis of LPS subtypes, especially between WDLPS and DDLPS.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-017-0309-5) contains supplementary material, which is available to authorized users.

Global epigenetic profiling identifies methylation subgroups associated with recurrence-free survival in meningioma

Meningioma is the most common primary brain tumor and carries a substantial risk of local recurrence. Methylation profiles of meningioma and their clinical implications are not well understood. We hypothesized that aggressive meningiomas have unique DNA methylation patterns that could be used to better stratify patient management. Samples (n = 140) were profiled using the Illumina HumanMethylation450BeadChip. Unsupervised modeling on a training set (n = 89) identified 2 molecular methylation subgroups of meningioma (MM) with significantly different recurrence-free survival (RFS) times between the groups: a prognostically unfavorable subgroup (MM-UNFAV) and a prognostically favorable subgroup (MM-FAV). This finding was validated in the remaining 51 samples and led to a baseline meningioma methylation classifier (bMMC) defined by 283 CpG loci (283-bMMC). To further optimize a recurrence predictor, probes subsumed within the baseline classifier were subject to additional modeling using a similar training/validation approach, leading to a 64-CpG loci meningioma methylation predictor (64-MMP). After adjustment for relevant clinical variables [WHO grade, mitotic index, Simpson grade, sex, location, and copy number aberrations (CNAs)] multivariable analyses for RFS showed that the baseline methylation classifier was not significant (p = 0.0793). The methylation predictor, however, was significantly associated with tumor recurrence (p < 0.0001). CNAs were extracted from the 450k intensity profiles. Tumor samples in the MM-UNFAV subgroup showed an overall higher proportion of CNAs compared to the MM-FAV subgroup tumors and the CNAs were complex in nature. CNAs in the MM-UNFAV subgroup included recurrent losses of 1p, 6q, 14q and 18q, and gain of 1q, all of which were previously identified as indicators of poor outcome. In conclusion, our analyses demonstrate robust DNA methylation signatures in meningioma that correlate with CNAs and stratify patients by recurrence risk.

Relationship of immunohistochemistry, copy number aberrations and epigenetic disorders with BRCAness pattern in hereditary and sporadic breast cancer

The study aims to identify the relevance of immunohistochemistry (IHC), copy number aberrations (CNA) and epigenetic disorders in BRCAness breast cancers (BCs). We studied 95 paraffin included BCs, of which 41 carried BRCA1/BRCA2 germline mutations and 54 were non hereditary (BRCAX/Sporadic). Samples were assessed for BRCA1ness and CNAs by Multiplex Ligation-dependent Probe Amplification (MLPA); promoter methylation (PM) was assessed by methylation-specific-MLPA and the expression of miR-4417, miR-423-3p, miR-590-5p and miR-187-3p by quantitative RT-PCR. IHC markers Ki67, ER, PR, HER2, CK5/6, EGFR and CK18 were detected with specific primary antibodies (DAKO, Denmark). BRCAness association with covariates was performed using multivariate binary logistic regression (stepwise backwards Wald option). BRCA1/2 mutational status (p = 0.027), large tumor size (p = 0.041) and advanced histological grade (p = 0.017) among clinic-pathological variables; ER (p < 0.001) among IHC markers; MYC (p < 0.001) among CNA; APC (p = 0.065), ATM (p = 0.014) and RASSF1 (p = 0.044) among PM; and miR-590-5p (p = 0.001), miR-4417 (p = 0.019) and miR-423 (p = 0.013) among microRNA expression, were the selected parameters significantly related with the BRCAness status. The logistic regression performed with all these parameters selected ER+ as linked with the lack of BRCAness (p = 0.001) and MYC CNA, APC PM and miR-590-5p expression with BRCAness (p = 0.014, 0.045 and 0.007, respectively). In conclusion, the parameters ER expression, APC PM, MYC CNA and miR-590-5p expression, allowed detection of most BRCAness BCs. The identification of BRCAness can help establish a personalized medicine addressed to predict the response to specific treatments.

Intra-Tumor Genetic Heterogeneity in Wilms Tumor: Clonal Evolution and Clinical Implications

The evolution of pediatric solid tumors is poorly understood. There is conflicting evidence of intra-tumor genetic homogeneity vs. heterogeneity (ITGH) in a small number of studies in pediatric solid tumors. A number of copy number aberrations (CNA) are proposed as prognostic biomarkers to stratify patients, for example 1q+ in Wilms tumor (WT); current clinical trials use only one sample per tumor to profile this genetic biomarker. We multisampled 20 WT cases and assessed genome-wide allele-specific CNA and loss of heterozygosity, and inferred tumor evolution, using Illumina CytoSNP12v2.1 arrays, a custom analysis pipeline, and the MEDICC algorithm. We found remarkable diversity of ITGH and evolutionary trajectories in WT. 1q+ is heterogeneous in the majority of tumors with this change, with variable evolutionary timing. We estimate that at least three samples per tumor are needed to detect >95% of cases with 1q+. In contrast, somatic 11p15 LOH is uniformly an early event in WT development. We find evidence of two separate tumor origins in unilateral disease with divergent histology, and in bilateral WT. We also show subclonal changes related to differential response to chemotherapy. Rational trial design to include biomarkers in risk stratification requires tumor multisampling and reliable delineation of ITGH and tumor evolution.

Detection of Circulating Tumor DNA in the Blood of Cancer Patients: An Important Tool in Cancer Chemoprevention

Liquid biopsies represent novel promising tools to determine the impact of clonal heterogeneity on clinical outcomes with the potential to identify novel therapeutic targets in cancer patients. We developed a low-coverage whole-genome sequencing approach in order to noninvasively establish copy number aberrations in plasma DNA from metastasized cancer patients. Using plasma-Seq we were able to monitor genetic evolution including the acquirement of novel copy number changes, such as focal amplifications and chromosomal polysomies. The big advantage of our approach is that it can be performed on a benchtop sequencer, speed, and cost-effectiveness. Therefore, plasma-Seq represents an easy, fast, and affordable tool to provide the urgently needed genetic follow-up data. Here we describe our method including plasma DNA extraction, library preparation, and bioinformatic analyses.

Estimation of the Survival of Patients With Lung Squamous Cell Carcinoma Using Genomic Copy Number Aberrations

BACKGROUND

Estimation of the survival of patients with lung squamous cell carcinoma (SCC) on the basis of histopathology is inadequate. The aim of this study was to identify genomic regions with potential value for estimating the prognosis of these patients.

PATIENTS AND METHODS

Depending on their survival time, 100 patients with primary lung SCC were separated into high- or low-risk prognostic groups, and their copy number aberrations (CNAs) were analyzed using array-comparative genomic hybridization (array-CGH).

RESULTS

We identified 123 CNA regions that were significantly associated with survival. Among these regions, some have been reported previously (eg, amplifications of 8p12, 3q27.1, and loss of 9p21.3 and 13q34) but others have never been reported. For example, gains of 3q27.1, 5p13.2, and 5p13.3 were found to be associated with a favorable prognosis, but patients harboring gains of 11q23.3, 11q13.1, and 14q32.3, and deletions of 3p21.3 and 9p21.3 tended to have poor survival. Among the 123 CNA regions, 41 were further selected to construct a survival estimation model that could effectively separate SCC patients into high- or low-risk groups with an accuracy of 92%, sensitivity of 90%, and specificity of 94%. The results of the array-CGH were further validated in an independent cohort of 45 formalin-fixed, paraffin-embedded specimens using real-time polymerase chain reaction.

CONCLUSION

A number of CNA regions were found to be associated with the survival of SCC patients, and we were able to construct a model to estimate prognosis on the basis of these regions. Assessment of these CNAs could potentially assist in clinical decision-making regarding adjuvant therapy after surgery.

Genetic changes observed in a case of adult pilocytic astrocytoma revealed by array CGH analysis

BACKGROUND

A palette of copy number changes in a case of adult pilocytic astrocytoma analyzed by Array Comparative Genomic Hybridization (aCGH) is presented. Pilocytic astrocytomas are specific gliomas that are benign and biologically distinct and the molecular mechanisms responsible for their development remain unexplained. The aCGH was performed using SurePrint G3 Human CGH microarrays 4 × 180 K (Agilent Technologies). To ascertain whether some of the aberrations were of constitutive nature, we also analyzed the blood sample from the same patient.

RESULTS

The result of aCGH analysis demonstrated differences in the tumor tissue when compared to normal control on the array and also to autologous DNA from patient's blood. The total number of aberrations found in our case was 41 including 37 deletions and 4 amplifications. Whole chromosomal gains and losses were not observed. Collectively, our results showed three deletions and one amplification at 1p, two deletions at 2q, two deletions at 4q, two deletion at 5q, two deletions at 7p and two deletions at 7q; there were also three deletions at 8q, one deletion at 9p, one deletion at 10p, three deletions and one amplification at 10q. Chromosome 11 showed two deletions at 11p, while there was one deletion at 12p and one at 12q. Four deletions at 14q; two deletions at 15q, one amplification at 17q and one deletion at 17q; one deletion at 18p, two deletions at 22q and finally one deletion at Xp and one deletion and one amplification at Xq. Among the signaling pathways, olfactory transduction, Fc gamma R-mediated phagocytosis and p53 signaling pathway showed significant enrichment ascertained by gene ontology (GO) analysis using the DAVID software.

CONCLUSIONS

Our aCGH analysis is bringing subtle genomic alterations thus broadening genetic spectrum of adult pilocytic astrocytoma in order to offer new molecular biomarkers that will help in diagnostics and therapeutic decision-making.

The mutational landscape of prostate cancer

CONTEXT

Prostate cancer (PCa) is a clinically heterogeneous disease with marked variability in patient outcomes. Molecular characterization has revealed striking mutational heterogeneity that may underlie the variable clinical course of the disease.

OBJECTIVE

In this review, we discuss the common genomic alterations that form the molecular basis of PCa, their functional significance, and the potential to translate this knowledge into patient care.

EVIDENCE ACQUISITION

We reviewed the relevant literature, with a particular focus on recent studies on somatic alterations in PCa.

EVIDENCE SYNTHESIS

Advances in sequencing technology have resulted in an explosion of data regarding the mutational events underlying the development and progression of PCa. Heterogeneity is the norm; few abnormalities in specific genes are highly recurrent, but alterations in certain signaling pathways do predominate. These alterations include those in pathways known to affect tumorigenesis in a wide spectrum of tissues, such as the phosphoinositide 3-kinase/phosphatase and tensin homolog/Akt pathway, cell cycle regulation, and chromatin regulation. Alterations more specific to PCa are also observed, particularly gene fusions of ETS transcription factors and alterations in androgen signaling. Mounting data suggest that PCa can be subdivided based on a molecular profile of genetic alterations.

CONCLUSIONS

Major advances have been made in cataloging the genomic alterations in PCa and understanding the molecular mechanisms underlying the disease. These findings raise the possibility that PCa could soon transition from being a poorly understood, heterogeneous disease with a variable clinical course to being a collection of homogenous subtypes identifiable by molecular criteria, associated with distinct risk profiles, and perhaps amenable to specific management strategies or targeted therapies.