Project description:The identification of genomic alterations occurring in neoplastic lesions provides insight into both lesion occurrence and disease progression. In this study we used microarray comparative genomic hybridization (CGH) to investigate genetic changes in atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS), as the presence of these lobular neoplastic lesions is an indicator of risk in the development of invasive breast cancer. DNA was extracted from microdissected archival breast tissue containing ALH or LCIS, lacking adjacent invasive carcinoma, and subjected to whole-genome tiling path microarray-CGH using the submegabase resolution tiling set (SMRTr)-array platform. Twelve ALH and 13 LCIS lesions were examined. Copy number alterations were identified using statistical criteria and validated with Real-Time PCR and fluorescence in situ hybridization. From statistical analysis, a greater number of alterations were observed in ALH compared to LCIS. Alterations common to ALH include gain at 2p11.2 and loss at 7p11.2-p11.1 and 22q11.1. Alterations common to LCIS include gain at 20q13.13 and loss at 19q13.2-q13.31. In both ALH and LCIS, we observed loss of 16q21-q23.1, an altered region previously identified in lobular neoplasia and invasive carcinoma. The validation of select alterations reinforces the genomic signature. This study represents the first whole-genome investigation of lobular neoplastic breast lesions using clinical archival specimens. The identified genomic signature includes copy number alterations not previously identified for lobular neoplasia. This genomic signature, common to ALH and LCIS, suggests a role for the acquisition of novel genomic alterations in the aberrant cellular proliferation that defines lobular neoplasia. Keywords: comparative genomic hybridization, high resolution analysis of atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS) human archival breast lesions by whole genome tiling path array CGH

Project description:Low grade flat ductal intraepithelial neoplasia (DIN1a, flat epithelial atypia) is one of the earliest morphologically recognizable neoplastic lesions of the breast. Frequently, it occurs in association with lobular intraepithelial neoplasia (LIN). The aim of this study was to elucidate chromosomal aberrations in these early neoplastic breast lesions using array comparative genomic hybridization (CGH) analysis. Laser capture microdissection of 12 archival formalin-fixed, paraffin-embedded specimens harbouring both foci of DIN1a as well as LIN was performed. All analyzed cases of DIN1a and LIN showed chromosomal gains and losses. The aberration encountered most often was loss on 16q in 7 DIN1a (70%) and 10 LIN (91%) cases. Regarding changes in chromosome 1, four DIN1a (40%) and 7 LIN (64%) cases showed a gain on 1q. The results of our study show concurrent chromosomal aberrations of 1q gains and 16q losses in several cases with coexisting LIN and low grade flat DIN. These aberrations are known to be common in low grade invasive ductal carcinomas as well as more advanced (conventional) types of low grade DIN (low grade ductal carcinoma in-situ). Our results raise the possibility of similar molecular-genetic pathways in most of the cases with coexisting LIN and low grade flat DIN. In this study, 11 cases of classic lobular intraepithelial neoplasias and 10 cases with several areas of low grade flat DIN (DIN1a or flat epithelial atypia) were analyzed by array CGH. Sections of formalin-fixed paraffin-embedded (FFPE) specimens cut at 7-8µm were mounted on special foil-coated slides (Molecular Devices, San Diego, USA). The sections were then deparaffinized with Xylene, processed in decreasing concentrations of ethanol and stained with haematoxylin. Lasercapture microdissection for both lesions was performed at multiple sites using Veritas Arcturus. For reference-DNA, female mammary tissue without histomorphological changes obtained from reduction mammoplasty specimens was procecessed and laser-microdissected as explained above. Cells were digested in 10µl TE, pH 9, and 0.5µl proteinase K (20mg/ml) for 48h at 55°C. After inactivation of proteinase K at 99°C for 10min, the digest was stored at -20°C. Without any further purification, the complete digest was used for whole genome amplification by means of the WGA (Whole Genome Amplification) kit from Sigma following the manufacturer’s recommendations. Array CGH was performed as described previously. In brief, two µg of amplified tumor and reference DNA were labelled by random priming (BioPrime® Total Genomic Labeling System, Invitrogen, Carlsbad, CA) with Alexa Fluor® 3 and Alexa Fluor® 5, respectively, and hybridized onto a tiling path BAC array, consisting of the human 32k BAC Re-Array Set (BACPAC Resources Center; http://bacpac.chori.org/pHumanMinSet.htm; DNA kindly provided by Pieter de Jong) and a 1Mb Resolution BAC set (clones kindly provided by Nigel Carter, Wellcome Trust Sanger Centre). All protocols are provided in detail on our website (http://www.molgen.mpg.de/~abt_rop/molecular_cytogenetics/) and more information concerning this platform have been submitted to the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/; GPL5114). For the analysis and visualization of array CGH data, our software-package CGH-PRO was employed. No background subtraction was applied. Raw data were normalized by “Subgrid LOWESS”. For the assessment of copy number gains and losses, we used circular binary segmentation in combination with log2 ratio thresholds of 0.15 and -0.15, respectively.

Project description:Lobular intraepithelial neoplasia grade 3 (LIN) is a recently recognized variant of intraepithelial lobular neoplasia of the breast composed of either uniform, generally small, cells (classic) with massive lobular distension, pleomorphic cells, signet-ring cells, or any cell type with necrosis. In contrast to classic forms of LIN, there is no consensus on therapeutic strategies for LIN3. In part this is due to the paucity of molecular data that could assist in defining the relationship of LIN3 to classic LIN and carcinomas. In this study we have employed array CGH to determine the patterns of chromosomal aberrations in 9 LIN3 lesions. By comparison to array CGH data of 13 classic LIN lesions, we demonstrate that LIN and LIN3 share several recurrent changes, in particular gains of 1q and losses of 16q. Both aberrations are known to appear early in tumorigenesis and to be associated with good prognosis. However, apart from this overlap, there were a number of karyotypic features that were observed exclusively in LIN3. Clearly, this lesion was characterized by a significantly higher number of DNA copy number changes (9 vs. 31 on average), a considerable complexity of chromosomal rearrangements with up to 16 breakpoints in one chromosome and overlapping high copy amplifications. The amplicons encompassed a number of known oncogenes such as ERBB2, CyclinD1 and FGF3 that have already been reported to be overexpressed in breast carcinomas. Our data suggest that, at the genetic level, LIN3 represents a highly advanced lesion with considerable resemblance to carcinomas and, therefore, reflects a lesion on the verge of invasion, and might represent the transition state from an intraepithelial neoplasm to breast carcinoma. In this study, nine cases of pleomorphic/necrotic LIN lesions as well as one classic LIN and the concurrent invasive lobular carcinoma (ILC) were analyzed by array CGH. Sections of formalin-fixed paraffin-embedded (FFPE) specimens cut at 7-8Âµm were mounted on special foil-coated slides (Molecular Devices, San Diego, USA). The sections were then deparaffinized with Xylene, processed in decreasing concentrations of ethanol and stained with haematoxylin. Lasercapture microdissection for both lesions was performed at multiple sites using Veritas Arcturus. For reference-DNA, female mammary tissue without histomorphological changes obtained from reduction mammoplasty specimens was procecessed and laser-microdissected as explained above. Cells were digested in 10Âµl TE, pH 9, and 0.5Âµl proteinase K (20mg/ml) for 48h at 55Â°C. After inactivation of proteinase K at 99Â°C for 10min, the digest was stored at -20Â°C. Without any further purification, the complete digest was used for whole genome amplification by means of the WGA (Whole Genome Amplification) kit from Sigma following the manufacturerâs recommendations. Array CGH was performed as described previously. In brief, two Âµg of amplified tumor and reference DNA were labelled by random priming (BioPrimeÂ® Total Genomic Labeling System, Invitrogen, Carlsbad, CA) with Alexa FluorÂ® 3 and Alexa FluorÂ® 5, respectively, and hybridized onto a tiling path BAC array, consisting of the human 32k BAC Re-Array Set (BACPAC Resources Center; http://bacpac.chori.org/pHumanMinSet.htm; DNA kindly provided by Pieter de Jong) and a 1Mb Resolution BAC set (clones kindly provided by Nigel Carter, Wellcome Trust Sanger Centre). All protocols are provided in detail on our website (http://www.molgen.mpg.de/~abt_rop/molecular_cytogenetics/) and more information concerning this platform have been submitted to the Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/; GLP: 5114). For the analysis and visualization of array CGH data, our software-package CGH-PRO was employed. No background subtraction was applied. Raw data were normalized by âSubgrid LOWESSâ. For the assessment of copy number gains and losses, we used circular binary segmentation in combination with log2 ratio thresholds of 0.15 and -0.15, respectively. High copy amplifications were defined by focal appearance and a log2 ratio exceeding 0.45. In order to statistically investigate the similarity of aberration profiles we applied Pearson's product-moment correlation to cbs ratios of each of the corresponding arrays.

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