Hyperforin and aristoforin inhibit lymphatic endothelial cell proliferation in vitro and suppress tumor-induced lymphangiogenesis in vivo.
The phloroglucinol derivative hyperforin, a major bioactive constituent of St. John's wort, is increasingly recognized as being able to regulate a variety of pathobiological processes and, thus, to possess potential therapeutic properties. In the context of cancer, hyperforin induces the apoptosis of cancer cells, inhibits angiogenesis and suppresses metastasis formation. Here, we report a new pharmacological function of hyperforin and its stabilized derivative aristoforin, namely the suppression of lymphatic endothelial cell (LEC) growth and lymphangiogenesis. At concentrations less than 10 microM, we found that these compounds induce cell cycle arrest of LECs, and at higher concentrations induce apoptosis. The loss of mitochondrial membrane potential and the activation of caspase-9 during the induction of apoptosis indicate that the intrinsic pathway of apoptosis is stimulated by these compounds, similar to the situation in tumor cells. In thoracic duct ring outgrowth assays, hyperforin and aristoforin both inhibited lymphangiogenesis, as evidenced by the suppression of lymphatic capillary outgrowth. In an in vivo animal model, both compounds were able to inhibit tumor-induced lymphangiogenesis. Together these data substantiate a new role for hyperforin and its derivatives as suppressors of lymphangiogenesis, and support their further investigation as potential anticancer drugs that target tumor growth and metastasis at multiple levels.
Rothley
Melanie
M
Forschungszentrum Karlsruhe, Institut für Toxikologie und Genetik, Postfach 3640, Karlsruhe, Germany.
Schmid
Anja
A
Thiele
Wilko
W
Schacht
Vivien
V
Plaumann
Diana
D
Gartner
Michael
M
Yektaoglu
Aybike
A
Bruyère
Françoise
F
Noël
Agnès
A
Giannis
Athanassios
A
Sleeman
Jonathan P
JP