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We report for the first time the controlled drug release from a nanoscale Zr-based metal–organic framework (MOF), UiO-66, in the presence of the enzyme alkaline phosphatase (ALP). This unprecedented reactivity was possible thanks to the prior functionalization of the MOF with N3–PEG–PO3ligands, which were designed for three specific aims: (1) to impart colloidal stability in phosphate-containing media; (2) to endow the MOF with multifunctionality thanks to azide groups for the covalent attachment of an imaging agent by click-chemistry; and (3) to confer stimuli-responsive properties, specifically the selective release of doxorubicin triggered by the enzymatic activity of ALP. Cell studies revealed that the functionalization of the MOF with N3–(PEG)20–PO3ligands improved their intracellular stability and led to a sustained drug release compared to the bare MOF. More importantly, an enhanced drug release was observed in cells with higher expression of ALP genes (HeLa versus MDA-MB-231 and MCF7), confirming the ALP-responsiveness of the system inside living cells.

Increased cancer stem cell content during development of resistance to tamoxifen in breast cancer is driven by multiple signals, including Sox2-dependent activation of Wnt signalling. Here, we show that Sox2 increases and estrogen reduces the expression of the transcription factor Sox9. Gain and loss of function assays indicate that Sox9 is implicated in the maintenance of human breast luminal progenitor cells. CRISPR/Cas knockout of Sox9 reduces growth of tamoxifen-resistant breast tumours in vivo. Mechanistically, Sox9 acts downstream of Sox2 to control luminal progenitor cell content and is required for expression of the cancer stem cell marker ALDH1A3 and Wnt signalling activity. Sox9 is elevated in breast cancer patients after endocrine therapy failure. This new regulatory axis highlights the relevance of SOX family transcription factors as potential therapeutic targets in breast cancer.

Stable reconstitution of vascular endothelial beds upon transplantation of progenitor cells represents an important challenge due to the paucity and generally limited integration/expansion potential of most identified vascular related cell subsets. We previously showed that mouse fetal liver (FL) hemato/vascular cells from day 12 of gestation (E12), expressing the Stem Cell Leukaemia (SCL) gene enhancer transgene (SCL‐PLAP+cells), had robust endothelial engraftment potential when transferred to the blood stream of newborns or adult conditioned recipients, compared to the scarce vascular contribution of adult bone marrow cells. However, the specific SCL‐PLAP+hematopoietic or endothelial cell subset responsible for the long‐term reconstituting endothelial cell (LTR‐EC) activity and its confinement to FL developmental stages remained unknown. Using a busulfan‐treated newborn transplantation model, we show that LTR‐EC activity is restricted to the SCL‐PLAP+VE‐cadherin+CD45−cell population, devoid of hematopoietic reconstitution activity and largely composed by Lyve1+endothelial‐committed cells. SCL‐PLAP+Ve‐cadherin+CD45−cells contributed to the liver sinusoidal endothelium and also to the heart, kidney and lung microvasculature. LTR‐EC activity was detected at different stages of FL development, yet marginal activity was identified in the adult liver, revealing unknown functional differences between fetal and adult liver endothelial/endothelial progenitors. Importantly, the observations that expanding donor‐derived vascular grafts colocalize with proliferating hepatocyte‐like cells and participate in the systemic circulation, support their functional integration into young livers. These findings offer new insights into the engraftment, phonotypical, and developmental characterization of a novel endothelial/endothelial progenitor cell subtype with multiorgan LTR‐EC activity, potentially instrumental for the treatment/genetic correction of vascular diseases. StemCells2017;35:507–521 (A): SCL‐PLAP+VE‐cad+CD45−, Lyve1+/‐(P+V+C−) fetal liver derived cells generate long term vascular endothelial clusters in different organs when intravenously transplanted into busulfan conditioned newborn recipient mice. P+V+C−cells contributed to endothelial cells (arrows) and also to rare blood cells (asterisks). Scale bars 50 μm. (B): As early as 3 weeks post‐transplantation, transferred fetal liver progenitor cells already form PLAP+vascular clusters (vc) in the host liver. The functionality of the vascular grafts is indicated by the presence of circulating cells in the vessels lumen (i, asterisk), implying their participation in the systemic circulation. Also the higher frequency of BrdU+hepatocytes‐like cells detected in expanding vascular cluster (in vc) areas (ii) compared with tissue areas outside the vascular clusters (out vc) (iv), suggests that donor‐host cellularity cross‐talk activity involved in proliferation control occurs during organ growth. At later stages (12 weeks), when the organ growth slows down and vascular graft expansion stabilizes, almost no BrdU+cells are observed within the vascular cluster areas (iiiand iv) indicating the absence of continuing proliferation in the grafted region. Scale bars 60 μm.

TGF-β secreted by tumor stroma induces epithelial-to-mesenchymal transition (EMT) in cancer cells, a reversible phenotype linked to cancer progression and drug resistance. However, exposure to stromal signals may also lead to heritable changes in cancer cells, which are poorly understood. We show that epithelial cells failing to undergo proliferation arrest during TGF-β-induced EMT sustain mitotic abnormalities due to failed cytokinesis, resulting in aneuploidy. This genomic instability is associated with the suppression of multiple nuclear envelope proteins implicated in mitotic regulation and is phenocopied by modulating the expression of LaminB1. While TGF-β-induced mitotic defects in proliferating cells are reversible upon its withdrawal, the acquired genomic abnormalities persist, leading to increased tumorigenic phenotypes. In metastatic breast cancer patients, increased mesenchymal marker expression within single circulating tumor cells is correlated with genomic instability. These observations identify a mechanism whereby microenvironment-derived signals trigger heritable genetic changes within cancer cells, contributing to tumor evolution.