The Aplidin Analogs PM01215 and PM02781 Inhibit Angiogenesis in Vitro and in Vivo

Background: Novel synthesized analogs of Aplidin, PM01215 and PM02781, were tested for antiangiogenic effects on primary human endothelial cells in vitro and for inhibition of angiogenesis and tumor growth in vivo.

Methods and Results: Both derivatives inhibited angiogenic capacities of human endothelial cells (HUVECs) in vitro at low nanomolar concentrations, as determined by real-time cell proliferation and migration, capillary tube formation and vascular endothelial growth factor (VEGF)-induced spheroid sprouting assays. Antiangiogenic effects of both analogs were observed in vivo in chicken chorioallantoic membrane (CAM) assays. In addition, growth of human multiple myeloma xenografts in the CAM was significantly reduced after application of both analogs. On the molecular level, both derivatives induced cell cycle arrest in G1 phase, as determined by flow cytometric analysis of endothelial cells. This growth arrest correlated with induction of the cell cycle inhibitor p16^INK4A and increased senescence-associated beta galactosidase activity. In addition, Aplidin analogs did not promote ER-stress, but induced oxidative stress and decreased production of the vascular maturation factors Vasohibin-1 and Dickkopf-3.

Conclusions: From these findings we conclude that both analogs are promising agents for the development of antiangiogenic drugs acting independent on classical inhibition of VEGF signaling.