title: Microscopical heat stress investigations under application of quantum dots.
abstract: Heat stress responses are analyzed in cancer cells by applying different microscopy techniques for targeting various fluorescently labeled or native structures. Thermotreatments are performed at 40, 45, 50, and 56 degrees C, respectively, for 30 min each, while controls were kept at 37 degrees C. Actin cytoskeletons labeled with Alexa Fluor 488-conjugated phalloidin are imaged by wide-field fluorescence microscopy (WFFM). Structural plasma membrane stabilities are labeled with fluorescent quantum dots and analyzed by laser scanning microscopy (LSM). High-resolution atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to study morphological features and surface structures. Fluorescence images reveal F-actin to be a comparatively thermolabile cell component showing distinctive alteration after heat treatment at 40 degrees C. Destabilization of actin cytoskeletons proceed with increasing stress temperatures. Active reorganization of plasma membranes coincidental to heat-induced shrinkage and rounding of cell shapes, and loosening of monolayered tissue are observed after treatment at 45 or 50 degrees C. Active stress response is inhibited by stress at 56 degrees C, because actin cytoskeletons as well as plasma membranes are destroyed, resulting in necrotic cell phenotypes. Comparing data measured with the same microscopic technique and comparing the different datasets with each other reveal that heat stress response in MX1 cells results from the overlap of different heat-induced subcellular defects.
authors.affiliation: Charité Universitätsmedizin in Berlin, Institut für Medizinische Physik und Lasermedizin, Campus Benjamin Franklin, Fabeckstrasse 60-62, D-14195 Berlin, Germany. c.dressler@lmtb.de
authors.forename: Cathrin
authors.initials: C
authors.lastname: Dressler
authors.forename: Olaf
authors.initials: O
authors.lastname: Minet
authors.forename: Jürgen
authors.initials: J
authors.lastname: Beuthan
authors.forename: Vladimir
authors.initials: V
authors.lastname: Novkov
authors.forename: Gerhard
authors.initials: G
authors.lastname: Müller
mesh_terms: D000199:Actins / Q000378:metabolism / Q000648:ultrastructure*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure*; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure*; D018869:Heat-Shock Response; D006358:Hot Temperature; D006801:Humans; D008301:Maleimides; D008560:Membrane Fluidity; D008856:Microscopy, Fluorescence / Q000379:methods*; D045663:Quantum Dots
chemical_list: D000199:Actins; C504424:Alexa Fluor 488 C5-maleimide; D008301:Maleimides