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CaArray_vince-00013: Integrated Genomics and Transcriptomic Analyses of Ductal Carcinoma In situ of the Breast

ABSTRACT: Purpose: To gain insight into genomic and trancriptomic subtypes of ductal carcinomas in situ of the breast (DCIS). Results: Thirty-two DCIS exhibited a luminal phenotype; 21were ERBB2 positive, and 4 were ERBB2/estrogen receptor (ER) negativewith1harboring a bona fide basal-like phenotype.Based on a CGHanalysis, genomic types were identified in this series of DCISwith the 1q gain/16q loss combination observed in 3 luminal DCIS, themixed amplifier pattern including all ERBB2,12 luminal and 1ERBB2/ER- DCIS, and the complex copy number alteration profile encompassing 14 luminal and 1ERBB2/ER- DCIS. Eight cases (8 of 57; 14%) presented aTP53 mutation, all being amplifiers. Unsupervised analysis of gene expression profiles of 26 of the 57 DCIS showed that luminal and ERBB2-amplified, ER-negative cases clustered separately.We further investigated the effect of high and low copy number changes on gene expression. Strikingly, amplicons but also low copy number changes especially on 1q, 8q, and 16q in DCIS regulated the expression of a subset of genes in a very similar way to that recently described in invasive ductal carcinomas. Conclusions: These combined approaches show that the molecular heterogeneity of breast ductal carcinomas exists already in in situ lesions and further indicate that DCIS and invasive ductal carcinomas share genomic alterations with a similar effect on gene expression profile.

ORGANISM(S): Homo sapiens

PROVIDER: GSE92697 | GEO | 2016/12/22

SECONDARY ACCESSION(S): PRJNA358385

REPOSITORIES: GEO

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Project description:Ductal carcinoma in situ (DCIS) is a non-invasive form of breast cancer where cells restricted to the ducts exhibit an atypical phenotype. Some DCIS lesions are believed to rapidly transit to invasive ductal carcinomas (IDCs), while others remain unchanged. Existing classification systems for DCIS fail to identify those lesions that transit to IDC. We studied gene expression patterns of 31 pure DCIS, 36 pure invasive cancers and 42 cases of mixed diagnosis (invasive cancer with an in situ component) using Agilent Whole Human Genome Oligo Microarrays 44k. Six normal breast tissue samples were also included as controls. qRT-PCR was used for validation. All DCIS and invasive samples could be classified into the intrinsic molecular subtypes defined for invasive breast cancer. Hierarchical clustering establishes that samples group by intrinsic subtype, and not by diagnosis. We observed heterogeneity in the transcriptomes among DCIS of high histological grade and identified a distinct subgroup containing seven of the 31 DCIS samples with gene expression characteristics more similar to advanced tumours. A set of genes independent of grade, ER-status and HER2-status was identified by logistic regression that univariately classified a sample as belonging to this distinct DCIS subgroup. qRT-PCR of single markers clearly separated this DCIS subgroup from the other DCIS, and contains samples from several histopathological and intrinsic molecular subtypes. The genes that differentiate between these two types of DCIS suggest several processes related to the re-organisation of the microenvironment. This raises interesting possibilities for identification of DCIS lesions both with and without invasive characteristics, which potentially could be used in clinical assessment of a woman's risk of progression, and lead to improved management that would avoid the current over- and under-treatment of patients. Breast cancer samples, 31 pure DCIS patients, 36 IDC patients, 42 mixed and 6 normal.

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CaArray_vince-00013: Integrated Genomics and Transcriptomic Analyses of Ductal Carcinoma In situ of the Breast

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