Fibromodulin Expression in Folliculostellate Cells and Pericytes Is Promoted by TGFβ Signaling in Rat Anterior Pituitary Gland

Positive and negative feedback regulation of the TGF-β1 explains two equilibrium states in skin aging

During aging, skin homeostasis is essential for maintaining appearance, as well as biological defense of the human body. In this study, we identified thrombospondin-1 (THBS1) and fibromodulin (FMOD) as positive and negative regulators, respectively, of the TGF-β1-SMAD4 axis in human skin aging, based on in vitro and in vivo omics analyses and mathematical modeling. Using transcriptomic and epigenetic analyses of senescent dermal fibroblasts, TGF-β1 was identified as the key upstream regulator. Bifurcation analysis revealed a binary high-/low-TGF-β1 switch, with THBS1 as the main controller. Computational simulation of the TGF-β1 signaling pathway indicated that THBS1 expression was sensitively regulated, whereas FMOD was regulated robustly. Results of sensitivity analysis and validation showed that inhibition of SMAD4 complex formation was a promising method to control THBS1 production and senescence. Therefore, this study demonstrated the potential of combining data-driven target discovery with mathematical approaches to determine the mechanisms underlying skin aging.

Role of Cancer Stem-like Cells in the Process of Invasion and Mesenchymal Transformation by a Reconstituted Triple-negative Breast Cancer Cell Population Resistant to p53-induced Apoptosis

We investigated the role of cancer stem cells (CSCs) in a population of triple-negative breast cancer (TNBC) cells that are resistant to apoptosis. A human breast cancer cell population capable of inducing p53 expression with doxycycline (Dox) was created and used as an untreated control (UT). After the addition of Dox to UT for 5 days, the cell population reconstituted with cells showing resistance to apoptosis was named RE. Fluorescence-activated cell sorting (FACS) and immunostaining revealed that after the addition of Dox, the ratio of cells in the S and G2/M phases decreased in UT as apoptosis proceeded, but did not markedly change in apoptosis-resistant RE. CSC-like cells in RE exhibited a cell morphology with a larger ratio of the major/minor axis than UT. FACS showed that RE had a higher proportion of CSC-like cells and contained more CD44+CD24- mesenchymal CSCs than ALDH1A3+ epithelial-like CSCs. In a Matrigel invasion assay, UT was more likely to form a three-dimensional cell population, whereas RE exhibited a planar population, higher migration ability, and the up-regulated expression of epithelial-mesenchymal transition-related genes. These results provide insights into the mechanisms by which TNBC cells acquire treatment resistance at the time of recurrence.

Stem-like Human Breast Cancer Cells Initiate Vasculogenic Mimicry on Matrigel

Vasculogenic mimicry (VM), referring to vasculogenic structures lined by tumor cells, can be distinguished from angiogenesis, and is responsible for the aggressiveness and metastatic potential of tumors. HCC1937/p53 cells were derived from triple-negative breast cancer (TNBC), and used to investigate the roles of breast cancer stem cells (CSCs) in the formation of VM. HCC1937/p53 cells formed mesh-like structures on matrigel culture in which expression of VM-related genes, vascular endothelial (VE)-cadherin, matrix metalloproteinase (MMP)-2 and MMP-9 was confirmed by droplet digital polymerase chain reaction (PCR). In immunofluorescence microscopy, aldehyde dehydrogenase (ALDH)1A3⁺ cells with properties of CSCs or progenitors and GATA binding protein 3 (GATA3)⁺ cells with more differentiated characteristics were localized in the bridging region and aggregated region of VM structures, respectively. In fluorescence-activated cell sorting analysis, ALDH⁺ cells, considered to be a subpopulation of CSCs sorted by the aldefluor assay, exhibited marked VM formation on matrigel in 24 hr, whereas ALDH⁻ cells did not form VM, indicating possible roles of CSCs in VM formation. The stem-like cancer cells resistant to p53-induced apoptosis, which expressed a high rate of ALDH1A3 and Sex-determining region Y (SRY)-box binding protein-2 (Sox-2), completed VM formation much faster than the control. These findings may provide clues to elucidate the significance of VM formed by treatment-resistant CSCs in the metastatic potential and poor prognosis associated with TNBC.