RGD-tachyplesin inhibits tumor growth

Tachyplesin is an antimicrobial peptide present in leukocytes of the horses hoe crab (Tachypleus tridentatus). In this study, a synthetic tachyplesin c onjugated to the integrin homing domain RGD was tested for antitumor activi ty. The in vitro results showed that RGD-tachyplesin inhibited the prolifer ation of both cultured tumor and endothelial cells and reduced the colony f ormation of TSU prostate cancer cells. Staining with fluorescent probes of FITC-annexin V, JC-1, YO-PRO-1, and FITC-dextran indicated that RGD-tachypl esin could induce apoptosis in both tumor and endothelial cells. Western bl otting showed that treatment of cells with RGD-tachyplesin could activate c aspase 9, caspase 8, and caspase 3 and increase the expression of the Fas l igand, Fas-associated death domain, caspase 7, and caspase 6, suggesting th at apoptotic molecules related to both mitochondrial and Fas-dependent path ways are involved in the induction of apoptosis. The in vivo studies indica ted that the RGD-tachyplesin could inhibit the growth of tumors on the chor ioallantoic membranes of chicken embryos and in syngenic mice.