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Identification of a minority population in breast cancer that integrates into the vasculature and initiates metastasis. [RNA-seq]

ABSTRACT: Metastasis is responsible for the majority of cancer-related deaths1. Although single-cell RNA sequencing (scRNA-seq) has revealed considerable heterogeneity among tumor cells, identifying the cellular determinants of metastasis has remained challenging. Here, we analyzed scRNA-seq data of primary human breast tumor biopsies and identified a minority population of immature THY1+/VEGFA+ basal epithelial cells that display angiogenic features and are marked by the expression of the oncogene, LMO2. Higher levels of LMO2+ basal cells in human breast tumors correlated with endothelial content and predicted poor distant recurrence-free survival. Using MMTV-PyMT/Lmo2CreERT2 mice, we demonstrate that Lmo2 lineage-traced cells integrate into the vasculature and metastasize to the lung. In human breast tumors, knockdown of LMO2 reduced lung metastasis by affecting multiple steps required for intravasation, leading to a reduced frequency of circulating tumor cells. Mechanistically, we find that LMO2 is a binding partner of STAT3 and is required for STAT3 activation in the presence of the inflammatory cytokines, TNFα and IL6. Collectively, our study identifies a population of metastasis-initiating cells with angiogenic features and establishes the LMO2-STAT3 signaling axis as a therapeutic target in breast cancer metastasis.

ORGANISM(S): Homo sapiens

PROVIDER: GSE159282 | GEO | 2023/10/08

REPOSITORIES: GEO

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Project description:Breast Cancer Subject Participant ID 700064 (Source Sample names: 6888 and 206). We used massively parallel DNA sequencing technologies to screen entire genomes, in an unbiased manner, for genetic changes associated with tumor growth and metastasis. We describe the complete genome sequence analysis of four DNA samples from a 44-year old African-American patient with basal-like breast cancer: peripheral blood, the primary tumor, a brain metastasis that developed within a year of initial therapy, and a first-passage xenograft derived from the primary tumor. A total of 50 validated mutations were discovered within coding, RNA, or splice site sequences. Of these, 20 mutations were abundantly present in all three tumors, including mutations in CSMD1 and JAK2. These two genes subsequently were found to be mutated in other breast tumors. The metastasis contained two de novo mutations not present in the primary tumor, and was significantly enriched for 20 shared mutations, suggesting that they may be involved in the metastatic process. The xenograft contained no unique coding, RNA, or splice site mutations and retained all primary tumor mutations, albeit at different frequencies. However, a significant increase in copy number alterations was observed in the xenograft as compared to the primary tumor. We validated 28 large deletions and six inversions, as well as seven translocations in at least one of the three tumor samples. Among them, a 26 kb deletion in MECR was solely identified, assembled, and validated in the brain metastasis and two overlapping large deletions on chromosome 5 encompassing CTNNA1, a potential tumor suppressor gene, were identified in all three tumors. The differential mutation frequencies and structural variation patterns between primary and metastatic tumors suggest that metastatic tumors may arise from minor subpopulations of cells within the primary. Namely, the metastatic and xenografting processes apparently select for cells harboring a distinct subset of the primary tumor mutation repertoire.

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Identification of a minority population in breast cancer that integrates into the vasculature and initiates metastasis. [RNA-seq]

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