Differential stromal reprogramming in benign and malignant naturally occurring canine mammary tumours identifies disease-promoting stromal components

Abstract

statement: RNAsequencing--based analysis of stromal reprogramming between benign and malignant naturally occurring canine mammary tumours identifies potential molecular drivers in cancer--associated stroma that support tumour growth and malignancy. AbstractThe importance of cancer--associated stroma (CAS) for initiation and progression of cancer is well accepted. However, as stromal changes in benign forms of naturally occurring tumours are poorly understood, it remains unclear how CAS from benign and malignant tumours compare. Spontaneous canine mammary tumours are viewed as excellent models of human mammary carcinomas (mCA). We have recently reported highly conserved stromal reprogramming between canine and human mCA based on transcriptome analysis of laser--capture-microdissected FFPE specimen. To identify stromal changes between benign and malignant mammary tumours, we have analysed CAS and matched normal stroma from 13 canine mammary adenomas and compared them to 15 canine mCA. Our analyses revealed distinct stromal reprogramming even in small benign tumours. While similarities in stromal reprogramming exist, the CAS signature clearly distinguished adenomas from mCA, suggesting that it may reliably discriminate between benign and malignant tumours. We identified strongly discriminatory genes and found strong differential enrichment in several hallmark signalling pathways between benign and malignant CAS. The distinction between CAS from adenoma and mCA was further substantiated by differential abundance in cellular composition. Finally, to determine key players in CAS reprograming between adenomas and mCA, a network--based gene screening method identified modules of co--expressing genes with distinct expression profile in benign and malignant CAS, and revealed several hub genes as potential molecular drivers in CAS. Given the relevance of canine CAS as a model for the human disease, our

Know Thy Model: Charting Molecular Homology in Stromal Reprogramming Between Canine and Human Mammary Tumors

“…This comparative dataset allowed us to interrogate for the first time the transcriptional levels of targets that have been implicated in stromal reprogramming of canine breast tumors thus far (see the sections "Cancer-Associated Fibroblasts and the Extracellular Matrix, " "Infiltrating Immune Cells, " and "Angiogenesis" for details). Figure 2 intends to give a schematic overview of changes in mRNA abundance of these targets between normal stroma, CAS in adenoma, and CAS in carcinoma as detected by our RNAseq approach (Amini et al, 2019b). These data give rise to several interesting observations: (i) some targets, such as αSMA, Tn-C, and VEGFA, show changes in FIGURE 2 | Overview of transcriptomic changes in selected markers during stromal reprogramming in canine mammary adenomas and carcinomas.…”

“…Since CAS has been shown to have important roles in determining the growth and progression of different tumor types, we hypothesized that differences in stromal reprogramming between benign adenomas and malignant mCA could contribute to the clinical behavior of these two tumor types. To begin to understand stromal reprogramming in naturally occurring benign tumors, we thus applied our approach to isolate and analyze CAS and normal stroma from FFPE tissue sections to 13 cases of canine simple mammary adenoma (Amini et al, 2019b). We observed clear separation of normal stroma and CAS samples, and identified 193 genes to be significantly deregulated between the two entities.…”

“…These data give rise to several interesting observations: (i) some targets, such as αSMA, Tn-C, and VEGFA, show changes in FIGURE 2 | Overview of transcriptomic changes in selected markers during stromal reprogramming in canine mammary adenomas and carcinomas. Schematic overview of transcriptomic changes of selected CAS-related markers based on our transcriptomic analyses of normal stroma, CAS from adenoma, and CAS from carcinoma isolated from canine breast tumor specimens (Amini et al, 2019b). Protein names on the left are targets whose expression in canine tumors has been investigated on protein level mostly by IHC (for details and references, see the main text).…”

A modern look at the molecular-biological mechanisms of breast tumours in dogs

“…Stroma plays an important role in the pathogenesis of breast tumours. A clear reprogramming of the stroma has been established even in the case of small benign breast tumours against the background of a significant difference between them and malignant tumours, with the key role of co-expressing genes, potential molecular drivers of this mechanism (Amini et al, 2019).…”