International Journal of Molecular Sciences Review Roles of Extracellular HSPs as Biomarkers in Immune Surveillance and Immune Evasion 1,2,3, 4, 1,5, , Eman A. Taha y, Kisho Ono y and Takanori Eguchi * y 1 Department of Dental Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan;
[email protected] 2 Department of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan 3 Department of Biochemistry, Ain Shams University Faculty of Science, Cairo 11566, Egypt 4 Department of Oral and Maxillofacial Surgery, Okayama University Hospital, Okayama 700-0914, Japan;
[email protected] 5 Advanced Research Center for Oral and Craniofacial Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan * Correspondence:
[email protected]; Tel.: +81-86-235-6662 These authors contributed equally to this work. y Received: 16 August 2019; Accepted: 14 September 2019; Published: 17 September 2019 Abstract: Extracellular heat shock proteins (ex-HSPs) have been found in exosomes, oncosomes, membrane surfaces, as well as free HSP in cancer and various pathological conditions, also known as alarmins. Such ex-HSPs include HSP90 (α, β, Gp96, Trap1), HSP70, and large and small HSPs. Production of HSPs is coordinately induced by heat shock factor 1 (HSF1) and hypoxia-inducible factor 1 (HIF-1), while matrix metalloproteinase 3 (MMP-3) and heterochromatin protein 1 are novel inducers of HSPs. Oncosomes released by tumor cells are a major aspect of the resistance-associated secretory phenotype (RASP) by which immune evasion can be established.