combined anti-CD47 antibodies with nanoparticles to target ovarian cancer cells [91]. outcomes. CD47 has emerged as a potential therapeutic target and is being investigated in various preclinical studies as well as clinical trials to prove its safety and efficacy in treating hematological neoplasms. This review focuses on different therapeutic mechanisms to target CD47, either alone or in combination with other cell surface markers, and Rabbit Polyclonal to TSPO its pivotal role in impairing tumor growth and metastatic spread of various types of hematological malignancies. Keywords:CD47, Immunotherapy, Targeted therapy, Hematological cancers == Background == == Structure and expression of CD47 == CD47 is a heavily glycosylated 50 Kd cell surface protein belonging to the immunoglobulin family, originally named integrin-associated protein (IAP) [1]. It has an extracellularN-terminal IgV domain, five transmembrane domains, and a short C-terminal cytoplasmic tail. The three domains are variable between humans and animals in terms of total amino acid composition, giving four alternative isoforms [2]. CD47 is expressed by virtually all cells in the body, including those that do not express integrins, such as erythrocytes. Therefore, it is now more appropriate to refer to it as CD47 Azacyclonol rather than IAP [3]. CD47 can be found in a bigger, more complex form associated with heparin and chondroitin sulfate glycosaminoglycan. This form Azacyclonol is expressed in both human and murine T-cells as well as endothelial cells and is responsible for signal inhibition after binding of T-cells to thrombospondins (TSPs) [4]. == Mechanism of function and intracellular signalling == CD47 plays an essential role in various cellular functions including proliferation, apoptosis, adhesion, migration, and numerous immune responses. This occurs via cell-cell as well as cell-extracellular matrix interactions. Sick and colleagues published an exhaustive review of the biological functions of CD47 [5]. These functions are mediated through the binding of CD47 Azacyclonol to its extracellular ligands such as signal regulatory proteins (SRPs) [6,7] and thrombospondins (TSPs) [4,5,8]; membrane ligands such as integrins [9], vascular endothelial growth factor receptor-2 (VEGFR-2) [4], CD36 [8], and Fas (CD95) [10]; as well as intracellular ligands such as Giproteins [11], BNIP3 [6], and Src and mitogen-activated protein kinases (MEK) [9] and protein 4.2 [12]. Figure1summarizes the CD47 structure and its ligands. == Fig. 1. == CD47 Structure and binding partners. CD47 is a transmembrane protein with 5 transmembrane domains, short intracytoplasmic C-terminal andN-terminal extracellular immunoglobulin variable (IgV) domain. Schematic diagram showing that CD47 can interact with v3 integrin on the same cell or with SIRP on the phagocytic cell through its IgV domain and activates dont eat me signal. CD47 can also bind thrombospondin-1 (TSP) in theN-terminal, which promotes an interaction between CD47 and v3 integrin and triggers v3 integrin signaling == Interaction with extracellular ligands == == SIRP == is a transmembrane glycoprotein expressed on myeloid cells such as granulocytes, monocytes, macrophages, dendritic cells, and their precursors, including hematopoietic stem cells, as well as neuronal cells [13]. It is also known as CD172a, Src homology 2 domain-containing protein tyrosine phosphatase substrate-1 (SHPS-1) or brain immunoglobulin-like molecule with tyrosine-based activation motifs (BIT). It consists of an extracellularN-terminal domain composed of three immunoglobulin-like and a cytoplasmic domain, which has two tyrosine phosphorylation sites and four immunoreceptor tyrosine inhibitory motifs (ITIMs) [14]. Binding of CD47 toN-terminal of SIRP on the phagocytic cells induces a phosphorylation reaction of the ITIM. This activates protein tyrosine phosphatases (PTPases) Src homology region 2 (SH2) domain-containing phosphatase1(SHP-1) and 2(SHP-2) [15]. Subsequently, dephosphorylation of immunoreceptor tyrosine activation motifs (ITAM) prevents the contractile engulfment by the macrophages and gives a don’t eat me signal to the innate immune system, a new signal that cancers seem to use to evade detection and destruction by the immune system [16]. == TSPs == are extracellular matrix calcium-binding glycoproteins regulating cell motility, proliferation, and differentiation [17]. Five isoforms of TSPs are currently known; TSP-1 is the first endogenous ligand identified for CD47. It is secreted by vascular and inflammatory cells that regulate cellular functions. It is a major component of platelet granules and is released upon activation [18]. Binding of TSP-1 through its C-terminal binding domain (CBD) peptide 4N1K, to extracellular IgV Azacyclonol of CD47,.