Unraveling the microenvironmental influences on the normal mammary gland and induction and progression of breast cancer

The normal mammary gland and invasive breast cancer are both complex 'organs' composed of multiple cell types as well as extracellular matrix (ECM) in three-dimensional (3D) space. Conventionally, both normal and malignant breast cells are studied in vitro as two-dimensional (2D) monolayers of epithelial cells, which results in the loss of structure and tissue function. Many laboratories are now investigating regulation of signaling function in normal mammary gland using 3D cultures. However, it is important also to assay malignant breast cells ex vivo in a physiologically relevant environment to more closely mimic tumor architecture, signal transduction regulation and tumor behavior in vivo. Here we present the potential of these 3D models for drug testing, target validation and guidance of patient selection for clinical trials. We argue also that in order to get full insight into the biology of the normal and malignant breast, and to create in vivo-like models for therapeutic approaches in humans, we need to continue to create more complex heterotypic models to approach the full context the cells encounter in the human body

Microarray-Based Class Discovery for Molecular Classification of Breast Cancer: Analysis of Interobserver Agreement

Background Breast cancers can be classified by hierarchical clustering using an "intrinsic" gene list into one of at least five molecular subtypes: basal-like, HER2, luminal A, luminal B, and normal breast-like. Five different intrinsic gene lists composed of varying numbers of genes have been used for molecular subtype identification and classification of breast cancers. The aim of this study was to determine the objectivity and interobserver reproducibility of the assignment of molecular subtype classes by hierarchical cluster analysis. Methods Three publicly available breast cancer datasets (n = 779) were subjected to two-way average-linkage hierarchical cluster analysis using five distinct intrinsic gene lists. We used free-marginal Kappa statistics to analyze interobserver agreement among five breast cancer researchers for the whole classification and for each molecular subtype separately according to each intrinsic gene list for each breast cancer dataset. Results None of the classification systems tested produced almost perfect agreement (Kappa >= 0.81) among observers. However, substantial interobserver agreement (70.8% to 76.1% of the samples and free-marginal Kappa scores from 0.635 to 0.701) was consistently observed in all datasets for four molecular subtypes (luminal, basal-like, HER2, and normal breast-like). When luminal cancers were subdivided (luminal A, B, and C), none of the classification systems produced substantial agreement (Kappa >= 0.61) in all the datasets analyzed. Analysis of each subtype separately revealed that only two (basal-like and HER2) could be reproducibly identified by independent observers (Kappa >= 0.81). Conclusions Assignment of molecular subtype classes of breast cancer based on the analysis of dendrograms obtained with hierarchical cluster analysis is subjective and shows modest interobserver reproducibility. For the development of a molecular taxonomy, objective definitions for each molecular subtype and standardized methods for their identification are required

The Birth of an Adenoid Cystic Carcinoma

Adenoid cystic carcinoma is a rare malignancy of exocrine glands defined by the presence of a dual population of cells (epithelial and myoepithelial cells) organized in varying combinations of cribriform, tubular, and solid patterns.1,2 This neoplasm most frequently originates in the salivary glands; however, it can also occur in other anatomical sites, including the breast.1,3 More than 90% of adenoid cystic carcinomas of the breast harbor the recurrent translocation t(6;9), resulting in the MYB-NFIB fusion gene, which leads to MYB overexpression.4 Adenoid cystic carcinoma in situ has been described in the breast; however, its identifica-tion is not trivial.3 Here, we illustrate an in situ adenoid cystic carcinoma partially involving a mammary duct in a 68-year-old woman with primary adenoid cystic carci-noma of the right breast. The double population of cells composing this intraductal lesion can be appreciated by its immunohistochemical profile (Figure 1). Given that the neoplastic cells of the in situ lesion already express MYB, our findings are consistent with the notion that MYB overexpression is an early event in the tumorigen-esis of adenoid cystic carcinomas.4,

Concordance among gene-expression-based predictors for breast cancer

BACKGROUND Gene-expression–profiling studies of primary breast tumors performed by different laboratories have resulted in the identification of a number of distinct prognostic profiles, or gene sets, with little overlap in terms of gene identity. METHODS To compare the predictions derived from these gene sets for individual samples, we obtained a single data set of 295 samples and applied five gene-expression–based models: intrinsic subtypes, 70-gene profile, wound response, recurrence score, and the two-gene ratio (for patients who had been treated with tamoxifen). RESULTS We found that most models had high rates of concordance in their outcome predictions for the individual samples. In particular, almost all tumors identified as having an intrinsic subtype of basal-like, HER2-positive and estrogen-receptor–negative, or luminal B (associated with a poor prognosis) were also classified as having a poor 70-gene profile, activated wound response, and high recurrence score. The 70-gene and recurrence-score models, which are beginning to be used in the clinical setting, showed 77 to 81 percent agreement in outcome classification

Whole‐exome sequencing and RNA sequencing analyses of acinic cell carcinomas of the breast

AimsAcinic cell carcinoma of the breast (ACC) is a rare histologic form of triple‐negative breast cancer (TNBC). Despite its unique histology, targeted sequencing analysis has failed to identify recurrent genetic alterations other than those found in common forms of TNBC. Here, we subjected three breast ACCs to whole‐exome and RNA‐sequencing, seeking to define whether they would harbor a pathognomonic genetic alteration.Methods and ResultsTumor and normal DNA and RNA samples from three breast ACCs were subjected to whole‐exome sequencing. Somatic mutations, copy number alterations, mutational signatures and fusion genes were determined using state‐of‐the‐art bioinformatics methods. Our analyses revealed TP53 hotspot mutations associated with loss of heterozygosity of the wild‐type allele in two cases. Mutations affecting homologous recombination (HR) DNA repair‐related genes were found in two cases, and an MLH1 pathogenic germline variant was detected in one case. In addition, copy number analysis revealed the presence of a somatic BRCA1 homozygous deletion and focal amplification of 12q14.3‐12q21.1, encompassing MDM2, HMGA2, FRS2 and PTPRB. No oncogenic in‐frame fusion transcript was identified in the three breast ACCs analyzed.ConclusionsNo pathognomonic genetic alterations were detected in the ACCs analyzed. These tumors have somatic genetic alterations similar to those of common forms of TNBC and may display HR deficiency or microsatellite instability. These findings provide further insights as to why ACCs which are usually clinically indolent may evolve into or in parallel with high‐grade TNBC

RNASeq analysis reveals biological processes governing the clinical behaviour of endometrioid and serous endometrial cancers

BACKGROUND: Endometrial carcinoma comprises a group of tumors with distinct histologic and molecular features, and clinical behavior. Here we sought to define the biological processes that govern the clinical behavior of endometrial cancers. METHODS: Sixteen prototype genes representative of different biological processes that would likely play a role in endometrial and other hormone-driven cancers were defined. RNA-sequencing gene expression data from 323 endometrial cancers from The Cancer Genome Atlas were used to determine the transcription module of each prototype gene. The expression of prototype genes and modules and their association with outcome was assessed in univariate and multivariate survival analyses. The association of MSH6 expression with outcome was validated in an independent cohort of 243 primary endometrial cancers using immunohistochemistry. RESULTS: We observed that the clinical behavior of endometrial carcinomas as a group was associated with hormone receptor signaling, PI3K pathway signaling and DNA mismatch repair processes. When analyzed separately, in endometrioid carcinomas, hormone receptor, PI3K and DNA mismatch repair modules were significantly associated with outcome in univariate analysis, whereas the clinical behavior of serous cancers was likely governed by apoptosis and Wnt signaling. Multivariate survival analysis revealed that MSH6 expression was associated with outcome of endometrial cancer patients independently from traditional prognostic clinicopathologic parameters, which was confirmed in an independent cohort at the protein level. CONCLUSION: Endometrioid and serous endometrial cancers are underpinned by distinct molecular pathways. MSH6 expression levels may be associated with outcome in endometrial cancers as a group

Stromal MED12 exon 2 mutations in complex fibroadenomas of the breast

© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. http://creativecommons.org/licenses/by-nc/4.0/This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.Aims: Here we explore the presence of mediator complex subunit 12 (MED12) exon 2 and telomerase reverse transcriptase (TERT) promoter hotspot mutations in complex fibroadenomas (CFAs) of the breast. Methods: The stromal components from 18 CFAs were subjected to Sanger sequencing of MED12 exon 2 and the TERT promoter hotspot loci. The epithelial and stromal components of two MED12 mutated CFAs were subjected to laser capture microdissection, and Sanger sequencing of MED12 exon 2, TERT promoter and PIK3CA exons 9 and 20, separately. Results: MED12 exon 2 mutations were identified in the stroma of 17% of CFAs. The analyses of epithelial and stromal components, microdissected separately, revealed that MED12 mutations were restricted to the stroma. No TERT promoter or PIK3CA mutations in exons 9 and 20 were detected in analysed CFAs. Conclusions: Like conventional fibroadenomas, MED12 exon 2 mutations appear to be restricted to the stromal component of CFAs, supporting the notion that CFAs are stromal neoplasms.This study was funded by the Breast Cancer Research Foundation. BW is funded by a Cycle for Survival grant, CS by a Fundação para a Ciência e Tecnologia grant (SFRH/BDE/110544/2015). FP is partially funded by a K12 CA184746 grant. The research reported in this paper was supported in part by a Cancer Centre Support Grant of the National Institutes of Health/National Cancer Institute (grant No P30CA008748).info:eu-repo/semantics/publishedVersio