Across the study interval, only early treatment with linezolid resulted in significant suppression of exotoxin synthesis and improved survival outcomes in a rabbit model of MRSA necrotizing pneumonia.
BackgroundIntrinsic and acquired resistance to drug therapies remains a challenge for malignant melanoma patients. Intratumoral heterogeneities within the tumor microenvironment contribute additional complexity to the determinants of drug efficacy and acquired resistance.MethodsWe use 3D biomimetic platforms to understand dynamics in extracellular matrix (ECM) biogenesis following pharmaceutical intervention against mitogen-activated protein kinases (MAPK) signaling. We further determined temporal evolution of secreted ECM components by isogenic melanoma cell clones.ResultsWe found that the cell clones differentially secrete and assemble a myriad of ECM molecules into dense fibrillar and globular networks. We show that cells can modulate their ECM biosynthesis in response to external insults. Fibronectin (FN) is one of the key architectural components, modulating the efficacy of a broad spectrum of drug therapies. Stable cell lines engineered to secrete minimal levels of FN showed a concomitant increase in secretion of Tenascin-C and became sensitive to BRAFV600E and ERK inhibition as clonally- derived 3D tumor aggregates. These cells failed to assemble exogenous FN despite maintaining the integrin machinery to facilitate cell- ECM cross-talk. We determined that only clones that increased FN production via p38 MAPK and β1 integrin survived drug treatment.ConclusionsThese data suggest that tumor cells engineer drug resistance by altering their ECM biosynthesis. Therefore, drug treatment may induce ECM biosynthesis, contributing to de novo resistance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2211-7) contains supplementary material, which is available to authorized users.
A recent combination of traction force microscopy with super resolution imaging allowed for novel research into the nanoscale architecture of force-bearing focal adhesions. Here we apply this technique to investigate the relation between local force exertion by the cell and the number of signal transduction proteins inside the integrin adhesome. Integrin adhesomes are mechanosensory protein complexes that couple the intracelular force bearing actomyosin structures to the extracelular environment. These complexes contain signal transduction proteins like paxillin, vinculin, talin and FAK, that change conformation when force is exerted on the complex. By immunostaining these proteins with Alexa647 their position can be localized to 20nm in fixed cells. However, due to the photophysical properties of Alexa647, and the binding stoichiometry in antibody staining the number of localizations does not scale linearly with the number of signal transduction proteins. To overcome this problem we present a novel analysis method to relate the number of localizations to the minimal number of signal transduction proteins.
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