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- Darai-Ramqvist, E, et al.
(författare)
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Segmental duplications and evolutionary plasticity at tumor chromosome break-prone regions
- 2008
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Ingår i: Genome research. - : Cold Spring Harbor Laboratory. - 1088-9051. ; 18:3, s. 370-379
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Tidskriftsartikel (refereegranskat)abstract
- We have previously found that the borders of evolutionarily conserved chromosomal regions often coincide with tumor-associated deletion breakpoints within human 3p12-p22. Moreover, a detailed analysis of a frequently deleted region at 3p21.3 (CER1) showed associations between tumor breaks and gene duplications. We now report on the analysis of 54 chromosome 3 breaks by multipoint FISH (mpFISH) in 10 carcinoma-derived cell lines. The centromeric region was broken in five lines. In lines with highly complex karyotypes, breaks were clustered near known fragile sites, FRA3B, FRA3C, and FRA3D (three lines), and in two other regions: 3p12.3-p13 (∼75 Mb position) and 3q21.3-q22.1 (∼130 Mb position) (six lines). All locations are shown based on NCBI Build 36.1 human genome sequence. The last two regions participated in three of four chromosome 3 inversions during primate evolution. Regions at 75, 127, and 131 Mb positions carry a large (∼250 kb) segmental duplication (tumor break-prone segmental duplication [TBSD]). TBSD homologous sequences were found at 15 sites on different chromosomes. They were located within bands frequently involved in carcinoma-associated breaks. Thirteen of them have been involved in inversions during primate evolution; 10 were reused by breaks during mammalian evolution; 14 showed copy number polymorphism in man. TBSD sites showed an increase in satellite repeats, retrotransposed sequences, and other segmental duplications. We propose that the instability of these sites stems from specific organization of the chromosomal region, associated with location at a boundary between different CG-content isochores and with the presence of TBSDs and “instability elements,” including satellite repeats and retroviral sequences.
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- De Bustos, Cecilia, et al.
(författare)
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Analysis of copy number variation in normal human population within a region containing complex segmental duplications on 22q11 using high resolution array-CGH
- 2006
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Ingår i: Genomics. - : Elsevier BV. - 0888-7543 .- 1089-8646. ; 88:2, s. 152-162
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Tidskriftsartikel (refereegranskat)abstract
- A previously detected copy number polymorphism (Ep CNP) in patients affected with neuroectodermal tumors led us to investigate its frequency and length in the normal population. For this purpose, a program called Sequence Allocator was developed and applied for the construction of an array that consisted of unique and duplicated fragments, allowing the assessment of copy number variation within regions of segmental duplications. The average resolution of this array was 11 kb and we determined the size of the Ep CNP to be 290 kb. Analysis of normal controls identified 7.7 and 7.1% gains in peripheral blood and lymphoblastoid cell line (LCL) DNA, respectively, while deletions were found only in the LCL group (7.1%). This array platform allows the detection of DNA copy number variation within regions of pronounced genomic complexity, which constitutes an improvement over available technologies.
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- Robertson, S, et al.
(författare)
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Prognostic value of Ki67 analysed by cytology or histology in primary breast cancer
- 2018
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Ingår i: Journal of clinical pathology. - : BMJ. - 1472-4146 .- 0021-9746. ; 71:9, s. 787-794
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Tidskriftsartikel (refereegranskat)abstract
- The accuracy of biomarker assessment in breast pathology is vital for therapy decisions. The therapy predictive and prognostic biomarkers oestrogen receptor (ER), progesterone receptor, HER2 and Ki67 may act as surrogates to gene expression profiling of breast cancer. The aims of this study were to investigate the concordance of consecutive biomarker assessment by immunocytochemistry on preoperative fine-needle aspiration cytology versus immunohistochemistry (IHC) on the corresponding resected breast tumours. Further, to investigate the concordance with molecular subtype and correlation to stage and outcome.MethodsTwo retrospective cohorts comprising 385 breast tumours with clinicopathological data including gene expression-based subtype and up to 10-year overall survival data were evaluated.ResultsIn both cohorts, we identified a substantial variation in Ki67 index between cytology and histology and a switch between low and high proliferation within the same tumour in 121/360 cases. ER evaluations were discordant in only 1.5% of the tumours. From cohort 2, gene expression data with PAM50 subtype were used to correlate surrogate subtypes. IHC-based surrogate classification could identify the correct molecular subtype in 60% and 64% of patients by cytology (n=63) and surgical resections (n=73), respectively. Furthermore, high Ki67 in surgical resections but not in cytology was associated with poor overall survival and higher probability for axillary lymph node metastasis.ConclusionsThis study shows considerable differences in the prognostic value of Ki67 but not ER in breast cancer depending on the diagnostic method. Furthermore, our findings show that both methods are insufficient in predicting true molecular subtypes.
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