The stromal cell-derived factor 1 (SDF1), also known as C-X-C motif chemokine 12 (CXCL12), is a chemokineprotein that in humans is encoded by the CXCL12gene on chromosome 10. It is ubiquitously expressed in many tissues and cell types. Stromal cell-derived factors 1-alpha and 1-beta are small cytokines that belong to the chemokine family, members of which activate leukocytes and are often induced by proinflammatory stimuli such as lipopolysaccharide, TNF, or IL1. The chemokines are characterized by the presence of 4 conserved cysteines that form 2 disulfide bonds. They can be classified into 2 subfamilies. In the CC subfamily, the cysteine residues are adjacent to each other. In the CXC subfamily, they are separated by an intervening amino acid. The SDF1 proteins belong to the latter group. CXCL12 signaling has been observed in several cancers. The CXCL12 gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.
This protein belongs to the intercrine alpha (chemokine CXC) family. SDF-1 is produced in two forms, SDF-1α/CXCL12a and SDF-1β/CXCL12b, by alternate splicing of the same gene. Chemokines are characterized by the presence of four conserved cysteines, which form two disulfide bonds. The CXCL12 proteins belong to the group of CXC chemokines, whose initial pair of cysteines are separated by one intervening amino acid. In addition, the first 8 residues of the CXCL12 N-terminal serve as a receptor binding site, though only Lys-1 and Pro-2 directly participated in activating the receptor. Meanwhile, the RFFESH motif (residues 12-17) in the loop region function as a docking site for CXCL12 receptor binding.
In adulthood, CXCL12 plays an important role in angiogenesis by recruiting endothelial progenitor cells (EPCs) from the bone marrow through a CXCR4 dependent mechanism.
CXCR4, previously called LESTR or fusin, is the receptor for CXCL12. This CXCL12-CXCR4 interaction used to be considered exclusive (unlike for other chemokines and their receptors), but recently, it was suggested that CXCL12 may also bind the CXCR7 receptor. By blocking CXCR4, a major coreceptor for HIV-1 entry, CXCL12 acts as an endogenous inhibitor of CXCR4-tropic HIV-1 strains.
In humans, CXCL12 has been implicated in a wide variety of biomedical conditions involving several organ systems. Chemokines and chemokine receptors, of which CXCR stands out, regulate multiple processes such as morphogenesis, angiogenesis, and immune responses and are considered potential targets for drug development. In the gastrointestinal tract system, the CXCL12-CXCR4 axis is under investigation as an anti-fibrotic therapy in the treatment for chronic pancreatitis. For instance, blocking CXCR4, the receptor for CXCL12, with Plerixafor (AMD-3100) increased the effectiveness of combretastatin in a mouse model of breast cancer, presumably by preventing macrophages from being recruited to tumours. Furthermore, CXCL12 signaling in conjunction with CXCR7 signaling has been implicated in the progression of pancreatic cancer. In the urinary tract system, methylation of the CXCL12 promoter and expression of PD-L1 may be powerful prognostic biomarkers for biochemical recurrence in prostate carcinoma patients after radical prostatectomy, and further studies are ongoing to confirm if CXCL12 methylation may aid in active surveillance strategies. In the field of oncology, melanoma associated fibroblasts are stimulated by stimulation of the A2B adenosine receptor followed by stimulation of fibroblast growth factor and increased expression of CXCL12.
A multi-locus genetic risk score study based on a combination of 27 loci, including the CXCL12 gene, identified individuals at increased risk for both incident and recurrent coronary artery disease events, as well as an enhanced clinical benefit from statin therapy. The study was based on a community cohort study (the Malmo Diet and Cancer study) and four additional randomized controlled trials of primary prevention cohorts (JUPITER and ASCOT) and secondary prevention cohorts (CARE and PROVE IT-TIMI 22).
^ abGuo JC, Li J, Zhou L, Yang JY, Zhang ZG, Liang ZY, Zhou WX, You L, Zhang TP, Zhao YP (August 2016). "CXCL12-CXCR7 axis contributes to the invasive phenotype of pancreatic cancer". Oncotarget. doi:10.18632/oncotarget.11330. PMID27542220.
^ abSorrentino C, Miele L, Porta A, Pinto A, Morello S (August 2016). "Activation of the A2B adenosine receptor in B16 melanomas induces CXCL12 expression in FAP-positive tumor stromal cells, enhancing tumor progression". Oncotarget. doi:10.18632/oncotarget.11729. PMID27590504.
^ abMega JL, Stitziel NO, Smith JG, Chasman DI, Caulfield MJ, Devlin JJ, Nordio F, Hyde CL, Cannon CP, Sacks FM, Poulter NR, Sever PS, Ridker PM, Braunwald E, Melander O, Kathiresan S, Sabatine MS (June 2015). "Genetic risk, coronary heart disease events, and the clinical benefit of statin therapy: an analysis of primary and secondary prevention trials". Lancet. 385 (9984): 2264–71. doi:10.1016/S0140-6736(14)61730-X. PMID25748612.
^De La Luz Sierra M, Yang F, Narazaki M, Salvucci O, Davis D, Yarchoan R, Zhang HH, Fales H, Tosato G (April 2004). "Differential processing of stromal-derived factor-1alpha and stromal-derived factor-1beta explains functional diversity". Blood. 103 (7): 2452–9. doi:10.1182/blood-2003-08-2857. PMID14525775.
^Crump MP, Gong JH, Loetscher P, Rajarathnam K, Amara A, Arenzana-Seisdedos F, Virelizier JL, Baggiolini M, Sykes BD, Clark-Lewis I (December 1997). "Solution structure and basis for functional activity of stromal cell-derived factor-1; dissociation of CXCR4 activation from binding and inhibition of HIV-1". The EMBO Journal. 16 (23): 6996–7007. doi:10.1093/emboj/16.23.6996. PMID9384579.
^Pavlasova G, Borsky M, Seda V, Cerna K, Osickova J, Doubek M, Mayer J, Calogero R, Trbusek M, Pospisilova S, Davids MS, Kipps TJ, Brown JR, Mraz M (August 2016). "Ibrutinib inhibits CD20 up-regulation on CLL B cells mediated by the CXCR4/SDF-1 axis". Blood. doi:10.1182/blood-2016-04-709519. PMID27480113.
^Takano T, Li YJ, Kukita A, Yamaza T, Ayukawa Y, Moriyama K, Uehara N, Nomiyama H, Koyano K, Kukita T (2014). "Mesenchymal stem cells markedly suppress inflammatory bone destruction in rats with adjuvant-induced arthritis". Laboratory Investigation; a Journal of Technical Methods and Pathology. 94 (3): 286–96. doi:10.1038/labinvest.2013.152. PMID24395111.
^Zheng H, Fu G, Dai T, Huang H (2007). "Migration of endothelial progenitor cells mediated by stromal cell-derived factor-1alpha/CXCR4 via PI3K/Akt/eNOS signal transduction pathway". Journal of Cardiovascular Pharmacology. 50 (3): 274–80. doi:10.1097/FJC.0b013e318093ec8f. PMID17878755.
^Balabanian K, Lagane B, Infantino S, Chow KY, Harriague J, Moepps B, Arenzana-Seisdedos F, Thelen M, Bachelerie F (2005). "The chemokine SDF-1/CXCL12 binds to and signals through the orphan receptor RDC1 in T lymphocytes". The Journal of Biological Chemistry. 280 (42): 35760–6. doi:10.1074/jbc.M508234200. PMID16107333.
^Oberlin E, Amara A, Bachelerie F, Bessia C, Virelizier JL, Arenzana-Seisdedos F, Schwartz O, Heard JM, Clark-Lewis I, Legler DF, Loetscher M, Baggiolini M, Moser B (1996). "The CXC chemokine SDF-1 is the ligand for LESTR/fusin and prevents infection by T-cell-line-adapted HIV-1". Nature. 382 (6594): 833–5. doi:10.1038/382833a0. PMID8752281.
^Goltz D, Holmes EE, Gevensleben H, Sailer V, Dietrich J, Jung M, Röhler M, Meller S, Ellinger J, Kristiansen G, Dietrich D (July 2016). "CXCL12 promoter methylation and PD-L1 expression as prognostic biomarkers in prostate cancer patients". Oncotarget. doi:10.18632/oncotarget.10786. PMID27462860.
Kucia M, Reca R, Miekus K, Wanzeck J, Wojakowski W, Janowska-Wieczorek A, Ratajczak J, Ratajczak MZ (August 2005). "Trafficking of normal stem cells and metastasis of cancer stem cells involve similar mechanisms: pivotal role of the SDF-1-CXCR4 axis". Stem Cells. 23 (7): 879–94. doi:10.1634/stemcells.2004-0342. PMID15888687.
Kryczek I, Wei S, Keller E, Liu R, Zou W (March 2007). "Stroma-derived factor (SDF-1/CXCL12) and human tumor pathogenesis". American Journal of Physiology. Cell Physiology. 292 (3): C987–95. doi:10.1152/ajpcell.00406.2006. PMID16943240.
Stellos K, Gawaz M (March 2007). "Platelets and stromal cell-derived factor-1 in progenitor cell recruitment". Seminars in Thrombosis and Hemostasis. 33 (2): 159–64. doi:10.1055/s-2007-969029. PMID17340464.
Arya M, Ahmed H, Silhi N, Williamson M, Patel HR (2007). "Clinical importance and therapeutic implications of the pivotal CXCL12-CXCR4 (chemokine ligand-receptor) interaction in cancer cell migration". Tumour Biology. 28 (3): 123–31. doi:10.1159/000102979. PMID17510563.