The role of Ephs, Ephrins, and growth factors in Kaposi sarcoma and implications of EphrinB2 blockade.
Kaposi sarcoma (KS) is associated with human herpesvirus (HHV)-8 and is dependent on the induction of vascular endothelial growth factors (VEGFs). VEGF regulates genes that provide arterial or venous identity to endothelial cells, such as the induction of EphrinB2, which phenotypically defines arterial endothelial cells and pericytes, and represses EphB4, which defines venous endothelial cells. We conducted a comprehensive analysis of the Eph receptor tyrosine kinases to determine which members are expressed and therefore contribute to KS pathogenesis. We demonstrated limited Eph/Ephrin expression; notably, the only ligand highly expressed is EphrinB2. We next studied the biologic effects of blocking EphrinB2 using the extracellular domain of EphB4 fused with human serum albumin (sEphB4-HSA). sEphB4-HSA inhibited migration and invasion of the KS cells in vitro in response to various growth factors. Finally, we determined the biologic effects of combining sEphB4-HSA and an antibody to VEGF. sEphB4-HSA was more active than the VEGF antibody, and combination of the 2 had at least additive activity. sEphB4-HSA reduced blood vessel density, pericyte recruitment, vessel perfusion, and increased hypoxia, with an associated increase in VEGF and DLL4 expression. The combination of sEphB4-HSA and VEGF antibody is a rational treatment combination for further investigation.
Department of Pathology, University of Southern California, 1441 Eastlake Avenue, Los Angeles, CA 90033, USA.
Jeffrey S
JS
Scehnet
Eric J
EJ
Ley
Valery
V
Krasnoperov
Ren
R
Liu
Parmeet K
PK
Manchanda
Eric
E
Sjoberg
Anna P
AP
Kostecke
Sachin
S
Gupta
S Ram
SR
Kumar
Parkash S
PS
Gill
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology; D036388:Ephrin-B2 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D036342:Ephrins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D036224:Receptor, EphB4 / Q000235:genetics / Q000378:metabolism*; D036081:Receptors, Eph Family / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology*; D012514:Sarcoma, Kaposi / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D012709:Serum Albumin / Q000235:genetics; D014469:Umbilical Arteries / Q000166:cytology; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A / Q000276:immunology; D019043:Vascular Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D023041:Xenograft Model Antitumor Assays
D000906:Antibodies; D036388:Ephrin-B2; D036342:Ephrins; D011993:Recombinant Fusion Proteins; D012709:Serum Albumin; D042461:Vascular Endothelial Growth Factor A; D036224:Receptor, EphB4; D036081:Receptors, Eph Family