Project description:To investigate the effect of macrophages on mammary basal cells, we established a macrophage depletion mouse model by clodronate liposome (CL) intraperitoneal injection, and the mammary basal cells were collected by FACS sorting. We then performed RNA-seq analysis on clodronate liposome (CL) treated mammary basal cells compared to control.
Project description:Basal breast cancers, an aggressive breast cancer subtype that has poor treatment options, are thought to arise from luminal mammary epithelial cells that undergo basal-like plasticity through poorly understood mechanisms. Using genetic mouse models and ex vivo primary organoid cultures, we show that conditional co-deletion of the LATS1 and LATS2 kinases, key effectors of Hippo pathway signaling, in mature mammary luminal epithelial cells promotes the development of basal-like carcinomas that metastasize over time. Genetic co-deletion experiments revealed that phenotypes resulting from the loss of LATS1/2 activity are dependent on the transcriptional regulators YAP/TAZ. Notably, transcriptional analyses of LATS1/2-deleted mammary epithelial cells revealed a gene expression program that associates with human basal breast cancers. Our study demonstrates in vivo roles for the LATS1/2 kinases in mammary epithelial homeostasis and luminal-basal fate control and implicates signaling networks induced upon the loss of LATS1/2 activity in the development of basal breast cancers.
Project description:Mammary epithelium is composed by luminal and basal epithelial cells, which are adhere to the basement membrane (BM). To dissect how basal cell functions are regulated by BM laminin adhesion, we performed RNA sequencing of basal human mammary epithelial cells adhered on laminin-111, -421 or -521 coated cell culture plates for 48 hours.
Project description:Molecular/cellular events that associate with epithelial-to-mesenchymal transition (EMT) are linked to acquisition of cancer stem cell traits, but whether EMT mechanisms regulate tissue epithelial cell fate and stem cell activity in vivo remains ambiguous. Using single-cell RNA sequencing, we detect heterogeneous EMT gene expression in stem cell-containing mammary basal/myoepithelial cells that normally possess both epithelial and smooth muscle characteristics. We show that EMT-inducing transcription factor Zeb1 is required within the mammary epithelium for ductal branching morphogenesis and regeneration, and that it promotes basal cell fate and regulates stem cell proliferation dynamics. We provide genetic and molecular evidence for EMT-dependent and -independent mechanisms of Zeb1 function, and show that Zeb1 cooperates with YAP to directly activate targets that inhibit Wnt signaling or control cell cycle. Together, our findings underscore Zeb1-mediated EMT control in governing mammary basal cell fate and proliferative activity, but with an interesting turn that involves mechanisms beyond EMT.
Project description:Wnt/β-catenin signaling pathway has become a key signaling pathway regulating mammary organogenesis and oncogenesis. However, the therapeutic methods by targeting Wnt pathway against breast cancer has been limited. To address this challenge, we investigated the function of cyclin-dependent kinase 14 (CDK14), a member of Wnt signaling pathway, in mammary development and breast cancer progression. We showed that CDK14 was expressed in the mammary basal layer and elevated in triple negative breast cancer (TNBC). CDK14 knockdown reduces colony formation ability and regeneration capacity of mammary basal cells, and significantly inhibits murine MMTV-Wnt-1 basal-like mammary tumor progression. Excitingly, knockdown of CDK14 or pharmacological inhibition of CDK14 by FMF-04-159-2 significantly inhibited the progression and metastasis of human TNBC. Mechanistically, CDK14 inhibition inhibits mammary regeneration and TNBC progression by attenuating Wnt/β-catenin signaling. Together, we demonstrated that CDK14 regulates mammary regeneration and breast tumorigenesis, and is a promising therapeutic target for TNBC.
Project description:Mammary ducts and alveoli are composed of basal and luminal cells, with the fate and differentiation of secreting cells being controlled by hormones through specific transcription factors. This study establishes the essential role of the histone H3 lysine 27 trimethylation (H3K27me3) demethylase KDM6A (UTX) in a balanced basal and luminal cell compartment. Disproportionate formation of basal cells in the absence of KDM6A resulted in disorganized mammary ducts and alveoli and lactation failure. Mutant luminal progenitors lost their distinctive transcription factor expression pattern and acquired basal characteristics leading to a preferential expansion of this lineage. The structure of mammospheres obtained from mutant progenitors suggested they were derived from basal progenitors. The genomic H3K27me3 landscape was unaltered in the absence of KDM6A suggesting demethylase-independent mechanisms. In support of this, mammary tissue developed normally in mice expressing a catalytically inactive KDM6A. This study demonstrated that mammary luminal progenitor cells rely on UTX to stably maintain their identity and thereby establish a balance of basal and luminal cells required for a functional mammary gland.
Project description:The mechanisms regulating breast cancer differentiation state are poorly understood. Of particular interest are molecular regulators controlling the highly aggressive and poorly differentiated traits of basal-like breast carcinomas. Here we show that the Polycomb factor EZH2 maintains the differentiation state of basal-like breast cancer cells, and promotes the expression of progenitor-associated and basal-lineage genes. Specifically, EZH2 regulates the composition of basal-like breast cancer cell populations by promoting a M-bM-^@M-^\bi-lineageM-bM-^@M-^] differentiation state, in which cells co-express basal- and luminal-lineage markers. We show that human basal-like breast cancers contain a subpopulation of bi-lineage cells, and that EZH2-deficient cells give rise to tumors with a decreased proportion of such cells. Bi-lineage cells express genes that are active in normal luminal progenitors, and possess increased colony formation capacity, consistent with a primitive differentiation state. We found that GATA3, a driver of luminal differentiation, performs a function opposite to EZH2, acting to suppress bi-lineage identity and luminal progenitor gene expression. GATA3 levels increase upon EZH2 silencing, leading to the observed decrease in bi-lineage cell numbers. Our findings reveal a novel role for EZH2 in controlling basal-like breast cancer differentiation state and intra-tumoral cell composition. Total of four treatments (HCC70 cells stably expressing shEZH2, shEED, or EZH2 cDNA, and MDA-MB-468 cells stably expressing shEZH2) were done in duplicates, each with its own control.
Project description:Skin-mammary specific knockout (SSKO) of Pygo2 (K14-cre; Pygo2 flox/-) , a WNT signaling co-activator, results in defective mouse mammary gland development. The FACS sorted mammary stem cell (MaSC)/basal population from Pygo2 SSKO mammary gland displays biased differentiation towards luminal/alveolar lineage in vitro, and reduced regeneration rate of new mammary gland in vivo To gain the insight into gene expression profiles in control and Pygo2 SSKO mammary epithelial cells (MECs), we sorted the freshly isolated mouse MECs into MaSC/basal (Lin-CD29hiCD24+) and mature luminal population (Lin-CD29lowCD24+CD61-), and extract total RNA for cDNA microarray analysis
Project description:Skin-mammary specific knockout (SSKO) of Pygo2 (K14-cre; Pygo2 flox/-) , a WNT signaling co-activator, results in defective mouse mammary gland development. The FACS sorted mammary stem cell (MaSC)/basal population from Pygo2 SSKO mammary gland displays biased differentiation towards luminal/alveolar lineage in vitro, and reduced regeneration rate of new mammary gland in vivo