473 research outputs found
Supplemental material for Serum heat shock protein 70 levels as a biomarker for inflammatory processes in multiple sclerosis
No full textSupplemental material for Serum heat shock protein 70 levels as a biomarker for inflammatory processes in multiple sclerosis by Patricia Lechner, Dorothea Buck, Lisa Sick, Bernhard Hemmer and Gabriele Multhoff in Multiple Sclerosis Journal – Experimental, Translational and Clinical</p
Correction: Wang, F.; Multhoff, G. Repurposing Cannabidiol as a Potential Drug Candidate for Anti-Tumor Therapies. Biomolecules 2021, 11, 582
No full textThere was a misplaced reference in the original article in the first paragraph of Section 6 “Clinical Trials with CBD” [...
The MICA-129Met/Val dimorphism affects plasma membrane expression and shedding of the NKG2D ligand MICA
No full textThe MHC class I chain-related molecule A (MICA) is a ligand for the activating natural killer (NK) cell receptor NKG2D. A polymorphism causing a valine to methionine exchange at position 129 affects binding to NKG2D, cytotoxicity, interferon-γ release by NK cells and activation of CD8+ T cells. It is known that tumors can escape NKG2D-mediated immune surveillance by proteolytic shedding of MICA. Therefore, we investigated whether this polymorphism affects plasma membrane expression (pmMICA) and shedding of MICA. Expression of pmMICA was higher in a panel of tumor (n = 16, P = 0.0699) and melanoma cell lines (n = 13, P = 0.0429) carrying the MICA-129Val/Val genotype. MICA-129Val homozygous melanoma cell lines released more soluble MICA (sMICA) by shedding (P = 0.0015). MICA-129Met or MICA-129Val isoforms differing only in this amino acid were expressed in the MICA-negative melanoma cell line Malme, and clones with similar pmMICA expression intensity were selected. The MICA-129Met clones released more sMICA (P = 0.0006), and a higher proportion of the MICA-129Met than the MICA-129Val variant was retained in intracellular compartments (P = 0.0199). The MICA-129Met clones also expressed more MICA messenger RNA (P = 0.0047). The latter phenotype was also observed in mouse L cells transfected with the MICA expression constructs (P = 0.0212). In conclusion, the MICA-129Met/Val dimorphism affects the expression density of MICA on the plasma membrane. More of the MICA-129Met variants were retained intracellularly. If expressed at the cell surface, the MICA-129Met isoform was more susceptible to shedding. Both processes appear to limit the cell surface expression of MICA-129Met variants that have a high binding avidity to NKG2D
Binding of heat shock protein 70 to extracellular phosphatidylserine promotes killing of normoxic and hypoxic tumor cells
No full textHypoxia is well known to limit curability of tumors by ionizing radiation. Here, we show that hypoxia treatment of tumor cells causes coexpression of heat shock protein 70 (Hsp70) and phosphatidylserine (PS) on the cell surface. Colocalization of Hsp70 and PS, as determined by confocal microscopy, also occurs when exogenous FITC-labeled Hsp70 protein is added to normoxic and hypoxic tumor cells. Moreover, the interaction of Hsp70 with PS was demonstrated in artificial unilamellar phosphatidylcholine/ phosphatidylserine (PC/PS) liposomes at the physiological ratio of 8/2. Indeed, the Hsp70-liposome interaction gradually increased with elevating PS molar ratios (8/2 > or = 7/3 < 5/5 < 4/6 < 3/7 < 2/8). In contrast, only a weak Hsp70 interaction was detected in phosphatidylcholine/phosphatidylglycerol (PC/PG) liposomes, thus demonstrating that the interaction was not a charge-related effect. The interaction of Hsp70 with surface PS significantly reduces clonogenic cell survival in normoxic (EC(50) of Hsp70=85 microg/ml) and hypoxic (EC(50) of Hsp70=55 microg/ml) tumor cells. The radiation-induced tumor cell killing was significantly enhanced by the addition of Hsp70 protein (50 microg/ml). Since apoptosis was not significantly enhanced in normoxic and hypoxic tumor cells by the addition of Hsp70, we hypothesize that the Hsp70 protein-induced reduction in clonogenic cell survival might be through necrosis rather than apoptosis
Influence of tumours on protective anti-tumour immunity and the effects of irradiation
No full textInnate and adaptive immunity play important roles in the development and progression of cancer and it is becoming apparent that tumours can influence the induction of potentially protective responses in a number of ways. The prevalence of immunoregulatory T cell populations in the circulation and tumours of patients with cancer is increased, and the presence of these cells appears to present a major barrier to the induction of tumour immunity. One aspect of tumour-mediated immunoregulation which has received comparatively little attention is that which is directed towards natural killer (NK) cells, although evidence that the phenotype and function of NK cell populations are modified in patients with cancer is accumulating.Although the precise mechanisms underlying these localised and systemic immunoregulatory effects remain unclear, tumour-derived factors appear, in part at least, to be involved. The effects could be manifested by an altered function and/or via an influence on the migratory properties of individual cell subsets. A better insight into endogenous immunoregulatory mechanisms and the capacity of tumours to modify the phenotype and function of innate and adaptive immune cells might assist the development of new immunotherapeutic approaches and improve the management of patients with cancer.This article reviews current knowledge relating to the influence of tumours on protective anti-tumour immunity and considers the potential influence that radiation-induced effects might have on the prevalence, phenotype and function of innate and adaptive immune cells in patients with cancer
Tumor-specific Hsp70 plasma membrane localization is enabled by the glycosphingolipid Gb3
No full textHuman tumors differ from normal tissues in their capacity to present Hsp70, the major stress-inducible member of the HSP70 family, on their plasma membrane. Membrane Hsp70 has been found to serve as a prognostic indicator of overall patient survival in leukemia, lower rectal and non small cell lung carcinomas. Why tumors, but not normal cells, present Hsp70 on their cell surface and the impact of membrane Hsp70 on cancer progression remains to be elucidated.Although Hsp70 has been reported to be associated with cholesterol rich microdomains (CRMs), the partner in the plasma membrane with which Hsp70 interacts has yet to be identified. Herein, global lipid profiling demonstrates that Hsp70 membrane-positive tumors differ from their membrane-negative counterparts by containing significantly higher amounts of globotriaoslyceramide (Gb3), but not of other lipids such as lactosylceramide (LacCer), dodecasaccharideceramide (DoCer), galactosylceramide (GalCer), ceramide (Cer), or the ganglioside GM1. Apart from germinal center B cells, normal tissues are Gb3 membrane-negative. Co-localization of Hsp70 and Gb3 was selectively determined in Gb3 membrane-positive tumor cells, and these cells were also shown to bind soluble Hsp70-FITC protein from outside in a concentration-dependent manner. Given that the latter interaction can be blocked by a Gb3-specific antibody, and that the depletion of globotriaosides from tumors reduces the amount of membrane-bound Hsp70, we propose that Gb3 is a binding partner for Hsp70. The in vitro finding that Hsp70 predominantly binds to artificial liposomes containing Gb3 (PC/SM/Chol/Gb3, 17/45/33/5) confirms that Gb3 is an interaction partner for Hsp70.These data indicate that the presence of Gb3 enables anchorage of Hsp70 in the plasma membrane of tumors and thus they might explain tumor-specific membrane localization of Hsp70
Activation of natural killer cells by heat shock protein 70.
No full textIntracellular heat shock proteins (HSP) function as molecular chaperones, they support folding and transport mechanisms of other proteins under physiological conditions and following physical or chemical stress. More recently, extracellular localized HSP have been found to play key roles in the induction of a cellular immune response. Either they act as carrier molecules for immunogenic peptides that are presented on Antigen Presenting Cells (APC) to cytotoxic T-cells or they themselves act as activatory molecules for the innate immune system. Binding of uncomplexed HSP to HSP-receptors on APC has been found to induce the secretion of inflammatory cytokines. Furthermore, an unusual tumor-selective membrane-localization of non-conserved regions of the 72 000 Da HSP (Hsp70) has been found to act as a recognition structure for natural killer (NK) cells. In this review the interaction of NK cells with Hsp70 or peptides derived thereof will be eluciated in more detail
Der Einfluss des Hitzeschockfaktor 1 (HSF-1) und der Hitzeschockproteine Hsp70 und Hsp27 auf die Radiosensitivität und Immunogenität
No full textHeat shock factor 1 (HSF-1) is a powerful, multifaceted modifier of carcinogenesis and cancer progression. HSF-1 activates the heat shock response following stress and is frequently upregulated in many tumor cell types already under physiological conditions. As HSF-1 is a key transcription factor for heat shock protein 70 (Hsp70) and 27 (Hsp27), protein levels of these HSPs are increased in numerous tumor cell types. Elevated HSP levels contribute to a malignant tumor phenotype and mediate resistance to chemo- and radiotherapy.
Apart from the blockage of HSF-1, the inhibition of Hsp90 is considered as a promising concept to overcome radioresistance. However, most Hsp90 inhibitors induce the release of HSF-1 from the Hsp90 complex and therefore HSF-1 becomes activated. Active HSF-1 induces the transcription of Hsp70 and Hsp27 that are known to promote tumor cell survival by interfering with anti-apoptotic pathways.
A dual targeting of the heat shock response with NZ28 and Hsp90 with NVP-AUY922 potentiates the radiation sensitivity of tumor cells that are otherwise resistant to ionizing radiation. NZ28 is known to interfere with the heat shock response by inhibiting not only HSF-1 but also several other transcription factors. Therefore, I wanted to study the combined effects of a specific HSF-1 and Hsp90 inhibition on the sensitivity of tumor cells to ionizing irradiation.
In addition to its cytoprotective properties when located intracellular, Hsp70 is also present on the plasma membrane (mHsp70) of many different tumor cell types. Membrane-bound Hsp70 exerts a dual function as it also mediates protection against ionizing irradiation but also plays a role in NK (natural killer) cell-mediated anti-cancer immunity, in vitro and in vivo. Besides Hsp70, MICA and B (major histocompatibility class I chain-related proteins A and B) are also important recognition structures (ligands) on tumor cells for activated NK cells.
As HSF-1 is not only known to regulate Hsp27 and Hsp70, but also the MICA/B expression, the effects of a specific HSF-1 knockdown were analyzed with respect to radiation sensitivity and NK cell-mediated tumor cell killing in two different lung carcinoma cell lines (H1339, EPLC-272H).
The depletion of HSF-1 resulted in a strong reduction of cytosolic Hsp70 levels, whereas the density of membrane-bound Hsp70 remained unchanged. Since mHsp70 also is involved in mediating radioresistance, a knockdown of HSF-1 alone was unable to increase radiosensitivity in H1339 and EPLC-272H cancer cell lines. Due to an HSF-1 mediated downregulation of MICB on the membrane of H1339 cells, NK cell-mediated lysis of these tumor cells was reduced. In contrast, the combined inhibition of HSF-1 and Hsp90 resulted in an increased radiosensitivity of H1339 cells. With respect to EPLC-272H ctrl and EPLC-272H HSF-1 knockdown sublines a combined treatment regimen did not induce an increased radiosensitivity. This finding might be due to the high basal Hsp27 levels in EPLC-272H cells which were not affected by an HSF-1 knockdown. Surprisingly, an Hsp27 knockdown promotes the transition from G2 to M phase after ionizing irradiation. A shorter G2 phase in which the DNA damage repair occurs presumably increases the number of chromosomal aberrations. Further studies are ongoing to fully understand the role of Hsp27 in DNA damage/cell cycle signaling pathways.Hitzeschockproteine (HSPs), auch Stressproteine genannt, wie z.B. Hsp90, Hsp70 und Hsp27 sowie deren Transkriptionsfaktor Hitzeschock Faktor 1 (HSF-1) können die Tumorprogression und die Strahlenresistenz auf vielfältige Weise unterstützen. Als Haupttranskriptionsfaktor für Hsp27 und Hsp70 aktiviert der HSF-1 die Stressantwort sowohl in Normal- als auch in Tumorzellen nach Stresseinwirkung (z.B. erhöhte Temperatur, Strahlentherapie, Toxine/Chemotherapeutika etc.). Im Gegensatz zu Normalzellen ist die Expression des HSF-1 in vielen Tumorzellarten bereits unter physiologischen Bedingungen hochreguliert. Aus diesem Grund ist die Expression der Stressproteine Hsp70 und Hsp27 in Tumorzellen unterschiedlicher Entitäten häufig ebenfalls erhöht. Ein hoher intrazellulärer HSP Gehalt trägt zu einem malignen Phänotyp des Tumors bei und kann außerdem Resistenzmechanismen gegen Chemo- und Strahlentherapie aktivieren, indem apoptotische Signaltransduktionswege gehemmt werden.
Neben Hsp70 und Hsp27 spielt auch Hsp90 eine wichtige Rolle in der Tumorgenese. In jüngster Zeit gilt die Hemmung von Hsp90 als ein vielversprechendes Konzept zur Erhöhung der Strahlenempfindlichkeit. Hsp90 wird in vielen Tumorzellarten ebenfalls vermehrt produziert und dient der Stabilisierung onkogener Zielproteine und den entsprechenden Signalwegen. Eine Inhibition von Hsp90 setzt jedoch HSF-1 aus dem Komplex mit Hsp90 frei und fördert somit dessen Aktivierung. Der freie aktivierte HSF-1 induziert daraufhin die Expression der anti-apoptotisch wirkenden Hitzeschockproteine Hsp70 und Hsp27.
Die simultane Inhibition der Stressantwort durch NZ28 und von Hsp90 durch NVP-AUY922 konnte die Strahlensensitivität in Tumorzellen, die bisher als radioresistent galten, signifikant erhöhen. NZ28 hemmt allerdings die Funktion von verschiedenen anderen Transkriptionsfaktoren und ist somit kein spezifischer Inhibitor für HSF-1. Deshalb wurden in der vorliegenden Arbeit die Effekte einer gezielten Herabregulation von HSF-1 untersucht.
Hsp70 wird nicht nur im Zellinneren, sondern auch auf der Membran von Tumorzellen exprimiert und dient dem Schutz der Zellen vor Bestrahlung. Neben dieser Funktion agiert Membran-gebundenes Hsp70 auch als Tumor-spezifische Zielstruktur für aktivierte NK (Natürliche Killer) Zellen. Neben Hsp70 fungieren auch MICA und MICB (major histocompatibility class I chain-related proteins A and B) auf der Oberfläche von Tumorzellen als wichtige NK Zell-spezifische Liganden.
Da der HSF-1 nicht nur die Expression von Hsp27 und Hsp70, sondern auch von MICA und MICB induziert, wurde von mir der Effekt eines HSF-1 Knockdown auf die intrazelluläre und Membran-Expression von Hsp27, Hsp70 und MICA/B in Bezug auf Radiosensitivität und die NK Zell-vermittelte Lyse von H1339 und EPLC-272H Lungenkrebszelllinien untersucht.
Ergebnisse: Die Herabregulation von HSF-1 führt zu einer starken Reduktion des zytosolischen Hsp70 in beiden Tumorzelltypen, beeinflusste jedoch nicht den Membranstatus von Hsp70. Ein alleiniger HSF-1 knockdown führte daher nicht zu der gewünschten Radiosensitivierung in den beiden Tumorzelllinien. Eine HSF-1 vermittelte Herabregulation von MICB auf der Zelloberfläche von H1339 Zellen führte überdies zu einer reduzierten NK Zell-vermittelten Tumorzelllyse von H1339 Zellen. Lediglich eine kombinierte Inhibition von HSF-1 und Hsp90 konnte die Radiosensitivität von H1339 Zellen signifikant erhöhen. Im Gegensatz zu H1339 Zellen konnten EPLC-272H Zellen durch eine Kombinationsbehandlung mit Hsp90 Inhibitor und HSF-1 Knockdown nicht strahlenempfindlicher gemacht werden. Ein Grund dafür könnte die hohe basale Expression von Hsp27 sein, die durch eine Herabregulation von HSF-1 nicht signifikant erniedrigt werden konnte.
Allerdings beschleunigt die Eliminierung von Hsp27 nach Bestrahlung den Übergang der Zellen von der G2 Phase in die Mitosephase. Diese Erniedrigung der G2 Phase, in der normalerweise die DNA Reparatur erfolgt, könnte dazu führen, dass Zellen mit einer erhöhten Anzahl an chromosomalen Aberrationen in den Zellzyklus gehen.
Weitere Untersuchungen sind derzeit in Bearbeitung, um die molekularen Mechanismen aufzuklären wie Hsp27 in die DNA Reparatur bzw. den Zellzyklus eingreift
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