2 research outputs found
DataSheet1_Microenvironment-Induced Non-sporadic Expression of the AXL and cKIT Receptors Are Related to Epithelial Plasticity and Drug Resistance.zip
<p>The existence of rare cancer cells that sporadically acquire drug-tolerance through epigenetic mechanisms is proposed as one mechanism that drives cancer therapy failure. Here we provide evidence that specific microenvironments impose non-sporadic expression of proteins related to epithelial plasticity and drug resistance. Microarrays of robotically printed combinatorial microenvironments of known composition were used to make cell-based functional associations between microenvironments, which were design-inspired by normal and tumor-burdened breast tissues, and cell phenotypes. We hypothesized that specific combinations of microenvironment constituents non-sporadically impose the induction of the AXL and cKIT receptor tyrosine kinase proteins, which are known to be involved in epithelial plasticity and drug-tolerance, in an isogenic human mammary epithelial cell (HMEC) malignant progression series. Dimension reduction analysis reveals type I collagen as a dominant feature, inducing expression of both markers in pre-stasis finite lifespan HMECs, and transformed non-malignant and malignant immortal cell lines. Basement membrane-associated matrix proteins, laminin-111 and type IV collagen, suppress AXL and cKIT expression in pre-stasis and non-malignant cells. However, AXL and cKIT are not suppressed by laminin-111 in malignant cells. General linear models identified key factors, osteopontin, IL-8, and type VIα3 collagen, which significantly upregulated AXL and cKIT, as well as a plasticity-related gene expression program that is often observed in stem cells and in epithelial-to-mesenchymal-transition. These factors are co-located with AXL-expressing cells in situ in normal and breast cancer tissues, and associated with resistance to paclitaxel. A greater diversity of microenvironments induced AXL and cKIT expression consistent with plasticity and drug-tolerant phenotypes in tumorigenic cells compared to normal or immortal cells, suggesting a reduced perception of microenvironment specificity in malignant cells. Microenvironment-imposed reprogramming could explain why resistant cells are seemingly persistent and rapidly adaptable to multiple classes of drugs. These results support the notion that specific microenvironments drive drug-tolerant cellular phenotypes and suggest a novel interventional avenue for preventing acquired therapy resistance.</p
Interfering with UDP-GlcNAc Metabolism and Heparan Sulfate Expression Using a Sugar Analogue Reduces Angiogenesis
Heparan sulfate (HS), a long linear
polysaccharide, is implicated
in various steps of tumorigenesis, including angiogenesis. We successfully
interfered with HS biosynthesis using a peracetylated 4-deoxy analogue
of the HS constituent GlcNAc and studied the compound’s metabolic
fate and its effect on angiogenesis. The 4-deoxy analogue was activated
intracellularly into UDP-4-deoxy-GlcNAc, and HS expression was inhibited
up to ∼96% (IC<sub>50</sub> = 16 μM). HS chain size was
reduced, without detectable incorporation of the 4-deoxy analogue,
likely due to reduced levels of UDP-GlcNAc and/or inhibition of glycosyltransferase
activity. Comprehensive gene expression analysis revealed reduced
expression of genes regulated by HS binding growth factors such as
FGF-2 and VEGF. Cellular binding and signaling of these angiogenic
factors was inhibited. Microinjection in zebrafish embryos strongly
reduced HS biosynthesis, and angiogenesis was inhibited in both zebrafish
and chicken model systems. All of these data identify 4-deoxy-GlcNAc
as a potent inhibitor of HS synthesis, which hampers pro-angiogenic
signaling and neo-vessel formation