Aberrant angiogenesis is essential for the progression of solid tumors and hematological malignancies. Thus, antiangiogenic therapy is one of the most promising approaches to control cancer. In the present work, we examined the ability of perillyl alcohol (POH), a dietary monoterpene with well-established tumor chemopreventive and chemotherapeutic activity, to interfere with the process of angiogenesis. POH remarkably prevented new blood vessel growth in the in vivo chicken embryo chorioallantoic membrane assay and proved to be effective in inhibiting the morphogenic differentiation of cultured endothelial cells into capillary-like networks both in collagen gel and Matrigel models. In addition, POH reduced the cell number in a proliferation assay and induced apoptosis of endothelial cells as indicated by the POH-mediated increase of caspase-3 activity and DNA fragmentation. Consistent with the observed antisurvival effect, POH treatment resulted in a significant inhibition of Akt phosphorylation in endothelial cells. Finally, POH was able to differentially modulate the release of two important angiogenic regulators: vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang2). POH decreased the release of VEGF from cancer cells but stimulated the expression of Ang2 by endothelial cells, indicating that it might suppress neovascularization and induce vessel regression. Overall, these data underscore the antiangiogenic potential of POH and suggest that POH, in addition to its anticancer activity, may be an effective agent in the treatment of angiogenesis-dependent diseases.

Mastic oil from Pistacia lentiscus var. chia, a natural plant extract traditionally used as a food additive, has been extensively studied for its antimicrobial activity attributed to the combination of its bioactive components. One of them, perillyl alcohol (POH), displays tumor chemopreventive, chemotherapeutic, and antiangiogenic properties. We investigated whether mastic oil would also suppress tumor cell growth and angiogenesis. We observed that mastic oil concentration and time dependently exerted an antiproliferative and proapoptotic effect on K562 human leukemia cells and inhibited the release of vascular endothelial growth factor (VEGF) from K562 and B16 mouse melanoma cells. Moreover, mastic oil caused a concentration-dependent inhibition of endothelial cell (EC) proliferation without affecting cell survival and a significant decrease of microvessel formation both in vitro and in vivo. Investigation of underlying mechanism(s) demonstrated that mastic oil reduced 1) in K562 cells the act...

Mastic oil from Pistacia lentiscus variation chia, a traditionally used dietary flavoring agent with medicinal properties, has been shown to exert in vitro antitumor activities, but no study has addressed in vivo efficacy and mechanisms of action. Presently, we demonstrated that treatment of immunocompetent mice with mastic oil (45 mg/kg body weight, intraperitoneally, 3 times a wk for ∼3 wk) significantly inhibited tumor growth (56.4% ± 5.7 maximum reduction in tumor volumes) without toxicity. Analysis of tumors by immunohistochemistry and ELISA indicated that this effect is associated with increased apoptosis, reduced neovascularization, and inhibition of chemokine expression. Likewise mastic oil reduced vascular endothelial growth factor and chemokine release by Lewis lung carcinoma (LLC) cells. Furthermore, mastic oil administration decreased small guanosine triphosphatases (GTPases) Ras, RhoA and nuclear factor-κ-B-dependent reporter gene expression in vivo and in vitro, indicating a mechanistic link between mastic oil activities and blocking of relevant signaling and transcription pathways. A dose-response comparison with perillyl alcohol and α-pinene, two of its components, revealed a higher efficacy of mastic oil, pointing to a beneficial collective interaction among its ingredients. Conclusively, our results provide novel in vivo evidence of mastic oil inhibitory effects on tumor growth and set a rational basis for its future application in cancer prevention.