PhD student-King's College London. Imaging and stimulation time courses are my life
Imaging endosome trafficking in 3D matrices - at least attempting to ....
Abstract: During their metastatic spread, cancer cells need to remodel the extracellular matrix in order to migrate through stromal compartments adjacent to the primary tumor. Dissemination of breast carcinoma cells is mediated by membrane type 1-matrix metalloproteinase (MT1-MMP/MMP14), the main invadopodial matrix degradative component. Here, we identify MT1-MMP as a novel interacting partner of dual-specificity LIM Kinase-1 and -2 (LIMK1/2), and provide several evidence for phosphorylation of tyrosine Y573 in the cytoplasmic domain of MT1-MMP by LIMK. Phosphorylation of Y573 influences association of F-actin binding protein cortactin to MT1-MMP-positive endosomes and invadopodia formation and matrix degradation. Moreover, we show that LIMK1 regulates cortactin association to MT1-MMP-positive endosomes, while LIMK2 controls invadopodia-associated cortactin. In turn, LIMK1 and LIMK2 are required for MT1-MMP-dependent matrix degradation and cell invasion in a three-dimensional type I collagen environment. This novel link between LIMK1/2 and MT1-MMP may have important consequences for therapeutic control of breast cancer cell invasion.
Pub.: 28 Apr '16, Pinned: 28 Sep '16
Abstract: Metastasis is responsible for most cancer-associated deaths. Accumulating evidence based on 3D migration models has revealed a diversity of invasive migratory schemes reflecting the plasticity of tumor cells to switch between proteolytic and nonproteolytic modes of invasion. Yet, initial stages of localized regional tumor dissemination require proteolytic remodeling of the extracellular matrix to overcome tissue barriers. Recent data indicate that surface-exposed membrane type 1-matrix metalloproteinase (MT1-MMP), belonging to a group of membrane-anchored MMPs, plays a central role in pericellular matrix degradation during basement membrane and interstitial tissue transmigration programs. In addition, a large body of work indicates that MT1-MMP is targeted to specialized actin-rich cell protrusions termed invadopodia, which are responsible for matrix degradation. This review describes the multistep assembly of actin-based invadopodia in molecular details. Mechanisms underlying MT1-MMP traffic to invadopodia through endocytosis/recycling cycles, which are key to the invasive program of carcinoma cells, are discussed. Expected final online publication date for the Annual Review of Cell and Developmental Biology Volume 32 is October 06, 2016. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Pub.: 09 Aug '16, Pinned: 28 Sep '16
Abstract: Antibody–drug conjugates (ADCs) represent an emerging new paradigm in cancer therapy. The approval of two ADCs has spurred considerable interest in this area of research, and over 55 ADCs are currently in clinical testing. In order to improve the clinical success rate of ADC therapy, all three components of the ADC: the antibody, linker, and payload have to be optimized. While considerable improvements have been made in antibody properties and target selection, medicinal chemistry efforts have lagged behind, and there is a significant need for innovation in linker design and payloads.
Pub.: 15 Sep '16, Pinned: 28 Sep '16
Abstract: The goal of targeted immunotherapy in cancer is to damage both malignant and tumor-supporting cells of the microenvironment but spare unaffected tissue. The malignant cells in classical Hodgkin lymphoma (cHL) selectively express CD30. They release this receptor on extracellular vesicles (EVs) for the tumor-supporting communication with CD30 ligand (CD30L)-positive bystander cells. Here, we investigated how CD30-positive EVs influence the efficacy of the CD30 antibody drug conjugate (ADC) Brentuximab Vedotin (SGN-35). The malignant cells and the EVs expressed the active sheddase ADAM10. ADAM10 cleaved and released the CD30 ectodomain (sCD30), causing a gradual depletion of SGN-35 binding sites on EVs and creating a soluble competitor of the ADC therapy. In a 3D semi-solid tumor microenvironment model, the EVs were retained in the matrix whereas sCD30 penetrated readily into the surrounding culture medium. This resulted in a lowered ratio of EV-associated CD30 (CD30EV) to sCD30 in the surrounding medium in comparison to non-embedded cultures. A low percentage of CD30EV was also detected in the plasma of cHL patients, supporting the clinical relevance of the model. The adherence of CD30EV but not sCD30 to CD30-/CD30L+ mast cells and eosinophils allowed the indirect binding of SGN-35. Moreover, SGN-35 damaged CD30-negative cells, provided they were loaded with CD30+ EVs.
Pub.: 23 Apr '16, Pinned: 12 Sep '16
Abstract: Fluorescence and surface-enhanced Raman scattering (SERS) spectroscopy were employed to investigate the cellular uptake of rhodamine 6G (R6G) alone and of R6G loaded with gold nanoparticles (AuNPs) by endothelial cells. R6G plays the role of a Raman reporter in SERS but also displays strong fluorescence. The presence of bare R6G molecules and R6G-AuNPs in the cytoplasm of the cells is detected via the 2D fluorescence of the dye after a 0.5 h of the incubation with R6G and R6G-AuNPs, and then the concentration of the dye increases within 4 h of exposure. The examination of the cellular uptake of the R6G and R6G-AuNPs species at different temperatures suggests that the internalization of the R6G-AuNPs into endothelial cells occurs mainly via endocytosis. 3D fluorescence imaging of R6G inside cells reveals inhomogeneous distribution of the dye in the cytoplasm. The SERS signal of the Raman reporter inside the cell disappears after 2 h of incubation with R6G-AuNPs and then amino acid residues, purines and pyrimidines become SERS-active via their interactions with the gold. The results highlight the significance of using multiple techniques to cover a spectrum of issues in the application of SERS nanosensors for probing an intracellular environment under comparable and standardized conditions. FigureCellular uptake of bare rhodamine 6G and rhodamine 6G adsorbed onto AuNPs were studied on endothelial cells using fluorescence and surface-enhanced Raman spectroscopy. The internalization of R6G-AuNPs occurs via endocytosis and diffusion resulting in uneven distribution in the cytoplasm.
Pub.: 09 Jan '15, Pinned: 12 Sep '16