Cell-surface expression of Hsp70 on hematopoietic cancer cells after inhibition of HDAC activity.

Laboratory of Immunology, Faculty of Life Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
Journal of leukocyte biology (Impact Factor: 4.99). 07/2009; 86(4):923-32. DOI: 10.1189/jlb.0209056
Source: PubMed

ABSTRACT We show that inhibition of HDAC activity leads to surface expression of Hsp70 on various hematopoietic cancer cells, an occurance that was not observed on naïve or activated peripheral blood cells. HDAC inhibitor-mediated Hsp70 surface expression was confined to the apoptotic Annexin V-positive cells and blocked by inhibition of apoptosis. Other chemotherapeutic inducers of apoptosis such as etoposide and camptothecin also led to a robust induction of Hsp70 surface expression. Hsp70 expression was, however, not caused by induction of apoptosis per se, as activated CD4 T cells remained Hsp70 surface-negative despite effective induction of apoptosis. Interestingly, inhibition of endolysosomes or normal ER/Golgi transport did not affect Hsp70 surface expression. Intracellular calcium and the transcription factor Sp1, which has been shown previously to be important for the intracellular stress mediated by HDAC inhibitors, were not involved in Hsp70 surface expression. We also found that HDAC inhibitors decreased cellular PMET activity and that a selective inhibition of PMET activity with extracellular NADH induced a robust Hsp70 surface expression. Our data suggest that inhibition of HDAC activity selectively induces surface expression of Hsp70 on hematopoietic cancer cells and that this may increase immunorecognition of these cells.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Introduction: Heat shock proteins (HSPs) are molecular chaperones that stabilize folding and conformation of mature proteins. HSPs are, therefore, considered as possible therapeutic targets in the treatment of human cancers, including acute myeloid leukemia (AML). This strategy offers the possibility of targeting several oncogenic proteins or several intracellular signaling pathways through the use of a single therapeutic agent. Areas covered: Several specific HSP70 inhibitors have now been developed. We describe: i) the molecular structure of HSP70 and the molecular interactions especially with its co-chaperones; ii) the immunoregulatory functions of HSP70; iii) the expression and function of HSP70 in human AML cells; iv) the molecular and pharmacological characteristics of potential HSP70 inhibitors; and v) the clinical and experimental studies of HSP70 inhibition in human AML. Our review is based on careful selection of relevant publications identified in the PubMed database. Expert opinion: HSP70 inhibitors have antileukemic activity in human AML. However, additional experimental studies using in vitro models as well as animal models are required, including detailed toxicology studies, as a scientific basis for the optimal design of future clinical studies.
    Expert Opinion on Therapeutic Targets 06/2014; DOI:10.1517/14728222.2014.924925 · 4.90 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract Purpose: Heat shock protein 70 (HSPA family) is a multi-functional protein which protects individual cells from proteotoxic shock and the whole organism from microbial, viral and oncogenic pathogens. These diverse functions may depend upon 'chaperone' activity that allows Hsp70 to regulate the mechanism of damaged protein recovery or utilisation inside a cell and to be a potent adjuvant, stimulating immune activity against a variety of viral or tumour antigens. The aim of this review is to present recent data on specific roles of intracellular and extracellular Hsp70 in cancerous tissue. Conclusion: The data presented in this paper show that endogenous Hsp70 protects cancer cells of different origins from a variety of cytotoxic threats including cancer cell therapeutics. In contrast, however, Hsp70 released from stressed cancer cells can serve as a danger signal or may recruit cells responsible for the generation of innate and adaptive immune responses against tumour cells.
    International Journal of Hyperthermia 07/2013; DOI:10.3109/02656736.2013.807439 · 2.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study we demonstrate that histone deacetylase (HDAC)-inhibitor mediated cell surface expression of the structural different NKG2D-ligands MICA/B and ULBP2 is calcium-dependent. Treatment with the calcium chelator EGTA inhibited constitutive as well as HDAC-inhibitor induced MICA/B and ULBP2 cell surface expression on melanoma cells and Jurkat T-cells. A NKG2D-dependent cytolytic assay and staining with a recombinant NKG2D-Fc fusion protein showed that calcium chelation impaired the functional ability of NKG2D-ligands induced by HDAC-inhibitor treatment. The HDAC-inhibitor induced cell surface expression of ULBP2, but not MICA/B, was sensitive to treatment calmidazolium and trifluoperazine, two agents known to block calcium signaling. siRNA-mediated knock-down of the calcium-regulated proteins calmodulin or calpain did however not affect NKG2D-ligand cell surface expression on Jurkat T-cells. We further show that secretion and cell surface binding of the calcium-regulating protein galectin-1 is enhanced upon HDAC-inhibitor treatment of melanoma cells. However, binding of galectin-1 to cell surface glycoproteins was not critical for constitutive or HDAC-inhibitor induced MICA/B and ULBP2 cell surface expression. We provide evidence that MICA/B and ULBP2 cell surface expression is controlled differently by calcium, which adds to the increasing perception that cell surface expression of MICA/B and ULBP2 is controlled by distinct signal transduction pathways.
    Molecular Immunology 09/2012; 53(3):255-64. DOI:10.1016/j.molimm.2012.08.011 · 3.00 Impact Factor