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Once a cluster of cancer cells reaches a diameter of about 1–2 mm, it must develop a blood supply in order to grow larger. Given that diffusion is no longer adequate to supply the cancerous cells with oxygen and nutrients and to remove wastes. Therefore, these cells secrete substances that promote the formation of new blood vessels (angiogenesis), which are vital for the growth and persistence of solid tumors and their metastases.
The production of several angiogenic factors (FGF-a, FGF-b, VEGF and VPF) is upregulated by tumors in order to stimulate angiogenesis. However, numerous malignant tumors also generate inhibitors of angiogenesis which include angiostatin and thrombospondin. The angiogenic phenotype is basically the end result of a net balance between the positive and negative regulators of neovascularization mentioned above. Endostatin’s role is to inhibit endothelial proliferation, therefore it is an effective angiogenesis inhibitor.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

Vimentin expression in human malignant glioma cells depends on cellular density, algorithms of drug delivery and chemo/radio treatment. Vimentin and detyrosinated microtubules provide structural support for the extensive microtentacles observed in detached tumor cells and a mechanism to promote successful metastatic spread. Primary colorectal carcinomas display aberrant expression of vimentin, and have activated Notch and TGFbeta signaling pathways. Vimentin is a strong arterial substrate for transglutaminases. Transglutaminase-mediated vimentin dimerization results in a novel unifying pathway by which vasodilatory and remodeling responses may be regulated. Ablation of vimentin expression inhibits migration and invasion of colon and breast cancer cell lines.

ACE-2 (Angiotensin converting enzyme 2) an enzyme bound to cell membranes in various organs such as intestines arteries , lungs, heart & kidney. ACE2 an entry receptor of SARS coronaviruses as well as SARS-CoV-2,.The coronavirus spike (S) glycoprotein is a class I viral fusion antigen located on the external envelope of the virion that takes part in a critical part in viral infection by identifying host cell receptors and facilitating fusion of the viral and cellular membranes. 2 main domains in coronavirus S1 have been recognized, the N-terminal domain and C-terminal domain. One or the other and/or both S1 domains function as a receptor-binding domain. SARS-CoV + MERS-CoV equally use C-domain to attach their receptors.ACE2 is a type I transmembrane antigen with an extracellular N-terminal domain having the catalytic site and an intracellular C-terminal tail. ACE2 obtains a signal peptide, a transmembrane domain, and a single metalloproteinase active site containing an HEXXH zinc-binding domain. ACE-2 plays a role as a mono-carboxypeptidase which degrades Ang I to produce the nonapeptide Ang 1–9 and Ang II to create the heptapeptide Ang 1–7.

The protein encoded by this gene is a member of the bone morphogenetic protein family which is part of the transforming growth factor-beta superfamily. The superfamily includes large families of growth and differentiation factors. Bone morphogenetic proteins were originally identified by an ability of demineralized bone extract to induce endochondral osteogenesis in vivo in an extraskeletal site. This particular family member plays an important role in the onset of endochondral bone formation in humans, and a reduction in expression has been associated with a variety of bone diseases, including the heritable disorder Fibrodysplasia Ossificans Progressiva. Alternative splicing in the 5' untranslated region of this gene has been described and three variants are described, all encoding an identical protein.

Adiponectin is an adipocyte specific secreted protein that circulates in the plasma. It is induced during adipocyte differentiation and its secretion is stimulated by insulin. Mouse adiponectin shares about 83% amino acid identity with that human. Adiponectin plays a role in various physiological processes such as energy homeostasis and obesity. Adiponectin is reduced in obese humans, and decreased level is associated with insulin resistance and hyperinsulinemia.

The Argonaute protein is part of the RISC or RNA-induced silencing complex, as so, the protein has a key part in the slicing processes of RNA. The RNA interference (RNAi) is being held by RISC. Small non-coding RNA fragments bond to the Argonaute proteins, through base pairing, eventually leads to the cleavage of messenger RNA or translation suppression.

ATG5 is a member of the autophagy-related (ATG) genes family. Autophagy is a catabolic process for the autophagosomic-lysosomal degradation of bulk cytoplasmic contents. ATG5 protein is essential for autophagy. It conjugates to ATG12 and associates with isolation membrane to form autophagosomes. In addition ATG5 takes a vital part in the apoptotic process and it is expressed relatively late in the apoptotic process, downstream of caspase activity.

Follistatin is a single-chain gonadal protein that specifically inhibits follicle-stimulating hormone release. The single FST gene encodes two isoforms, FST317 and FST344 containing 317 and 344 amino acids respectively, resulting from alternative splicing of the precursor mRNA. In a study in which 37 candidate genes were tested for linkage and association with polycystic ovary syndrome (PCOS) or hyperandrogenemia in 150 families, evidence was found for linkage between PCOS and follistatin. Follistatin binds directly to activin and functions as an activin antagonist. specific inhibitor of the biosynthesis and secretion of pituitary follicle stimulating hormone (fsh).

MAGEA5 belongs to the MAGEA gene family which encodes proteins with 50 to 80% sequence identity to each other. The promoters and first exons of the MAGEA genes are variable, which signify that the presence of this gene family enables the same role to be expressed under diverse transcriptional controls. The MAGEA genes are clustered at chromosomal location Xq28. They are associated with several hereditary disorders, like dyskeratosis congenita. MAGEA5 gene encodes a protein which is C-terminally truncated compared to other family members, and can be alternatively interpreted to be a pseudogene.

FGF8 is part of the fibroblast growth factor family. FGF family members have wide mitogenic and cell survival activities, and participate in a variety of biological processes, including embryonic development, cell growth, morphogenesis, tissue repair, tumor growth and invasion. FGF8 supports androgen and anchorage independent growth of mammary tumor cells. FGF8 over expression increases tumor growth and angiogensis. The adult expression of FGF-8 gene is restricted to testes and ovaries. FGF8 functions as an embryonic epithelial factor. FGF8 takes part in midbrain and limb development, organogenesis, embryo gastrulation and left-right axis determination.

TFPI is a protease inhibitor which controls the tissue factor (TF)-dependent pathway of blood coagulation. The coagulation process starts with the creation of a factor VIIa-TF complex, that proteolytically triggers additional proteases (factors IX and X) and eventually results in a fibrin clot. TFPI inhibits the activated factor X and VIIa-TF proteases in an autoregulatory loop. TFPI is glycosylated and predominantly located in the vascular endothelium and plasma in both free forms and complexed with plasma lipoproteins. A number of alternatively spliced transcript variants of this gene have are known, however the full-length nature of several of these variants were not yet established.

gAcrp30 globular protein, exists as a result of proteolytic processing of adiponectin. Adiponectin is manufactured and secreted solely by adipocytes, and is a highly obtained plasma protein, accounting for up to 0.05% of total serum protein. Similar to Adiponectin, gAcrp30 is able of lowering hyperglycemia and reversing INS resistance. In addition, gAcrp30 is an significant protein that is involved in promoting fat loss by signaling muscle to absorb and burn Free-Fatty Acids. AdipoR1 & AdipoR2 are the 2 signaling receptors for adiponectin and gAcrp30 that were recently been identified.

Alpha 1 ACT is an early-stage acute-phase plasma protein and a serpin that preferentially inactivates chymotrypsin, cathepsin G, and chymase. Alpha-1-ACT, a serine protease inhibitor, is tightly associated with amyloid plaques in Alzheimer's disease (AD) and in normal aged human and monkey brain.
Regulation of the serine proteases and serine protease inhibitors plays an important role in neuromuscular differentiation. Prostate specific antigen (PSA), a chymotrypsin-like serine protease, is predominantly complexed to Alpha-1-ACT.

NDRG2 belongs to the N-myc downregulated gene family that is a part of the alpha/beta hydrolase superfamily. NDRG2 takes part in dendritic and neuronal cell differentiation and outgrowth and is found in large quantities in heart, dendritic cells, brain, salivary gland and skeletal muscle and in small quantities in kidney and liver. In Alzheimer Disease (AD)-affected patients NDRG2 is found in brain lesions and is believed to be related to the progression of AD.

ARG1 catalyzes the hydrolysis of arginine to ornithine and urea. 2 isoforms of mammalian arginase exist which vary in their tissue distribution, subcellular localization, immunologic crossreactivity and physiologic role. ARG1 is a cytosolic enzyme and expressed widely in the liver as part of the urea cycle. Inherited deficiency of this ARG1 causes argininemia, which is an autosomal recessive disorder characterized by hyperammonemia.

ARPC5 is a 151 amino acid subunit of the Arp2/3 complex. ARPC5 is believed to have a role in maintaining the integrity of Arp2/3. ARPC5 is a substrate for MAPKAPK-2 which, via phosphorylation of ARPC5, may participate in Arp2/3 regulatory functions and remodeling of the Actin cytoskeleton.

Asialoglycoprotein Receptor 2 (ASGR2) is a hetero-oligomeric protein comprised of major and minor subunits, encoded by different genes. ASGR2 is a subunit of the asialoglycoprotein receptor; it is the less abundant minor subunit. The ASGR2 receptor is a transmembrane protein, which has a crucial role in serum glycoprotein homeostasis by mediating the endocytosis and lysosomal degradation of glycoproteins with exposed terminal galactose or N-acetylgalactosamine residues.

Twisted gastrulation Protein (TSG) is a secreted, cysteine-rich protein which has a role in dorsal/ventral patterning in Drosophila and Xenopus by regulating BMP signaling. TSG functions as an agonist for BMP signaling by controlling the inhibitory actions of the BMP antagonist, Chordin/Sog, and the cleavage properties of the metalloprotease, xolloid/tolloid. TSG N-terminal domain binds BMP protein directly and displays BMP antagonist activity.

Dendritic cell and monocyte chemokinelike protein (DMC/CXCL17/VEGF-correlated chemokine 1/VCC1), is a secreted molecule with a size and predicted 3-dimensional folding pattern similar to that of chemokines CXCL8/IL8 and CXCL14/BRAK. CXCL17 is constitutively generated by airway and intestinal epithelium. CXCL17 induces the chemotaxis of quiescent, but not LPS-activated peripheral blood monocytes and dendritic cells, and it also binds these cells specifically. The expression of CXCL17 is increased in endothelial cells when they are induced to form tubes in vitro. CXCL17, CXCL1/GRO and CXCL8/IL8 which have roles in angiogenesis, show significantly correlated expression with that of VEGF in primary lung, breast and esophageal tumors. Therefore, CXCL17 is suggested to have a role in tumor angiogenesis. The mature Rat CXCL17 shares 82%, 71% amino acid sequence identity with mouse, human CXCL17, respectively.

Nectin-1, also referred to as ED4, is a poliovirus receptor- related 1 protein is a part of the Nectin family. Nectin-1 endorses cell-cell contacts by forming homophilic or heterophilic trans-dimers. Heterophilic interactions among PVRL1/nectin-1 & PVRL4/nectin-4 and among PVRL1/nectin-1 & PVRL3/nectin-3 have been found. Nectin-1 acts as an entry receptor for herpes simplex virus & pseudorabies virus as well. Likewise, Neurite outgrowth-promoting activity has been shown by Nectin-1.

PFN2 is a ubiquitous actin monomer-binding protein which is part of the profilin family. PFN2 regulates actin polymerization in response to extra cellular signals. PFN2 binds to actin and affects the structure of the cytoskeleton. At high concentrations, profilin prevents the polymerization of actin, while it increases it at low concentrations. PFN2 binds to PIP2, it inhibits the formation of IP3 and DG.

Thrombopoietin is a glycoprotein hormone produced mainly by the liver and the kidney that regulates the production of platelets by the bone marrow. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that fragment into large numbers of platelets.