Growth stem cell factor

The potential for improved radioprotection by combining Tempol with growth factors such as stem cell factor (SGP), which protects by quite different mechanisms, has been examined in mice (82). Both SGP alone, given 20 and 4 h before and 4 h after TBI, and Tempol alone, given 10 min before TBI, increased 30-day survival, but protection was greater than additive when the two agents were combined. 

The most important survival and growth factor for mast cells is the KIT Ugand stem cell factor (SCF) [12], The hypothesis of early studies, that SCF might be elevated in skin lesions associated with mastocytosis [13], however, was not confirmed by later studies on SCF levels in skin and blood, at least for adult patients [14],... 

A variety of type 2 cytokines and the non-lymphoid cell-derived growth factor, stem cell factor (SCF) (Hiiltner et al., 1989 Copeland et al., 1990 Huang et al., 1990 Thompson-Snipes et al., 1991 reviewed in Befus, 1995), are known to be important in the development of intestinal mast cell responses associated with nematode infection but the contribution of this population to host protection depends on the nematode species in question. 

Growth factors, which are produced both as soluble and membrane-bound isotype proteins include members of the receptor tyrosine kinase subclass 111, such as stem cell factor (SCF) (Anderson et al, 1990 Huang et al, 1990), colony stimulating factor-1 (CSF-1, M-CSF) (Ladner et al, 1988 Ceretti et al, 1988) and Fit 3 ligand (Hannum et al, 1994 McClanahan et al, 1996). 

We used the stroma dependent Myl-D7 cell line to define unknown stem cell factors secreted by MSS stromal cells. CSF-1 was identified as a major growth factor component of the MSS supernatant by biochemical analysis. Recombinant CSF-1 induced short-term growth (3 days) of Myl-D7 to a similar extent as MSS CM. Furthermore, growth of the parental Myl-D7 clone in MSS CM could be inhibited by addition of an a-CSF-1 antibody, indicating that at least one of the active molecules is CSF-1. Thus we conclude that CSF-1 is a potent stimulator of the limited proliferation of the Myl-D7 stem cell line (Heberlein et al., 2006). 

Although Gleevec was carefully designed to inhibit the specific tyrosine kinase produced by the Philadelphia chromosome, it also produces unexpected activities. Gleevec blocks c-kit (the receptor for stem cell factor) [40], and the receptor for platelet-derived growth factor [41]. These additional activities could result in a broader array of antitumor activities, in a broader spectrum of toxicities, or both [42]. 

Imatinib (STI571) is an inhibitor of the tyrosine kinase domain of the Bcr-Abl oncoprotein and prevents the phosphorylation of the kinase substrate by ATP. It is indicated for the treatment of chronic myelogenous leukemia (CML), a pluripotent hematopoietic stem cell disorder characterized by the t(9 22) Philadelphia chromosomal translocation. This translocation results in the Bcr-Abl fusion protein, the causative agent in CML, and is present in up to 95% of patients with this disease. This agent inhibits other activated receptor tyrosine kinases for platelet-derived growth factor receptor (PDGFR), stem cell factor (SCF), and c-kit. 

Growth factors TGF-P, PDGF, HGF, EGF, IGF-I, IGF-II, aFGF, stem cell factor,... 

Dysbindin-2B has been identified as both stem cell factor apoptosis response protein 1 (SCF ARP1) by Lucas et al. (2005) and as a casein kinase 1 binding partner (CK1BP) by Yin et al. (2006). SCF ARP1 is expressed in bone marrow-derived myelomonocytic stem cells upon induction of apoptosis by withdrawal of stem cell growth factor SCF (Lucas et al., 2005). Programmed cell death via apoptosis controls stem cell numbers during hematopoietic cell development (Domen 2001). Since apoptosis is similarly important in development of neurons (Kuan et al., 2000 Buss and Oppenheim, 2004), dysbindin-2B may play a role in nervous system development (see also Section 2.2.33.1). 

Stem cell factor, SCF, also called steel factor or mast cell growth factor is a cytokine that stimulates the proliferation of myeloid and lymphoid hemopoietic progenitor cells. SCF is a ligand of the receptor tyrosine kinase, c-KIT, a protoonct ene. The KIT oncogene is the gene of a transforming feline sarcoma virus. 

Stem cell factor amplifies the proliferation and mobilization of myeloid, erythroid, and megakaryocyte colonies when combined with a lineage-specific hemopoietic growth factor (for example G-CSF, IL-3). Stem cell factor, added to other recombinant hemopoietic cytokines, is used to increase the mobilization of peripheral blood progenitor cells. 

Hematopoietic growth factors are glycoproteins produced by a number of peripheral and marrow cells. More than 200 billion blood cells are produced each day and the hematopoietic factors, along with other lymphopoietic factors such as- the. stem cell factor and the interleukins, are involved in the proliferation, differentiation, and maturation of various types of blood cells derived from the pluripotent stem cells. 

---