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Spatial heterogeneity of integrins and their ligands in primary breast tumors

ABSTRACT: The diversity of cell-cell interactions in different regions of a tumor reflects the functional heterogeneity of cancer, which poses challenges in early diagnosis, selection of treatment strategies, and prognosis of breast cancer. Cancer cells interact with each other to form different morphological structures in the tumor and stromal host cells via integrins. The objective of this study was to characterize the morphological and spatial heterogeneity of primary breast tumors in the context of expression profiles of integrins and their ligands. We studied spatial transcriptomics using the 10X Visium approach and the NICHES algorithm to map ligand-receptor signaling pathways and visualize the heterogeneity of signaling archetypes in tumor clusters. Cluster analysis of the expression profiles of tumor spots from the samples indicated pronounced inter-tumoral heterogeneity. Integrin-ligand functional clusters were associated with intratumoral heterogeneity, which was manifested by the presence of several morphological loci as observed in histological tumor samples. Inter-tumoral heterogeneity was manifested by a different number of functional clusters, ranging from 2 to 9 for each tumor sample. The main characteristic of these clusters was the significant predominance of non-complementary integrin subunits. Of the 42 functional integrin-ligand pairs in 21 clusters of five samples, 41 pairs occurred only once. The exception was the LAMA5-ITGB4 pair, which was detected in two clusters of different samples. The spatial heterogeneity of integrin-ligand expression clusters in breast cancer contributes significantly to the functional heterogeneity of the tumor, which sets the stage for many scenarios of parenchymatous-stromal relationships, some of which may be effective in the emergence of metastasizing tumor seed cells. The intra- and inter-tumoral spatio-functional heterogeneity of the tumor tissue that we discovered may largely explain why it is difficult to achieve success in most patients with breast cancer using any therapeutic strategy targeting one molecule of the vast array, regardless of the importance of its pathogenetic significance.

ORGANISM(S): Homo sapiens

PROVIDER: GSE242311 | GEO | 2023/09/08

REPOSITORIES: GEO

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Project description:Breast cancers display a high degree of diversity between and within tumors due to variations in both tumor cells and non-malignant cells of the tumor microenvironment (TME). While most studies on the TME have focused on stroma located within the tumor mass, few studies have examined the peri-tumoral microenvironment, which extends beyond the tumor margins and includes the surrounding, benign-appearing tissues. Here, we examined the heterogeneity in tumors and peri-tumoral stroma from 10 ER+PR+HER2- invasive breast carcinomas, through multi-region transcriptomic profiling. Tumor samples were obtained from the center, superior, inferior, medial, and lateral (C, S, Inf, M, L) regions of each tumor. Peritumoral samples were obtained from four radial directions corresponding to the regions the tumor samples were collected from (S, Inf, M, L) and from three zones of increasing distances from the tumor margins (Zone 1: 1-3 cm, Zone 2: 3-5 cm, Zone 3: 5-7 cm). To represent the normal breast transcriptomic state, 5 non-directional samples were each obtained from 3 non-tumor bearing breasts (NTB) - 1 patient had undergone cosmetic reduction mammoplasty and 2 patients were germline BRCA2-mutation carriers who had undergone risk-reducing mammoplasties. Total RNA was isolated and microarray was performed using the human Clariom™ S Assay (ThermoFisher Scientific). In total, 144 transcriptomic profiles (47 Tumor, 82 peri-tumoral stroma, 15 NTB) were analyzed. Heterogeneity was observed both within and between the tumor samples, highlighting that unlike the histological classification, an individual tumor is often comprised of several molecular sub-types. Similarly, the peri-tumoral stroma was also heterogeneous, albeit independent of the tumor heterogeneity. Four distinct stromal clusters were noted, which differed in their molecular pathways and cell type composition. Among these, the adipose-enriched stroma that had inflammatory cancer-associated fibroblasts and innate immune cells was significantly associated with poorer overall survival, in contrast to the myofibroblast-enriched stroma. These data together suggest that the peri-tumoral heterogeneity may be an important determinant of the evolution and treatment of breast cancers.

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Spatial heterogeneity of integrins and their ligands in primary breast tumors

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