METHODOLOGY/PRINCIPAL FINDINGS: PA exerted selective cytotoxicity on human umbilical vein endothelial cells (HUVECs) with IC(50) value of 6.91 ± 0.85 µM when compared to human normal fibroblast and normal liver epithelial cells. Assessment of the growth kinetics by cell impedance-based Real-Time Cell Analyzer showed that PA induced both cytotoxic and cytostatic effects on HUVECs, depending on the concentration used. Results also showed that PA suppressed VEGF-induced survival and proliferation of HUVECs. Furthermore, endothelial cell migration, invasion, and morphogenesis or tube formation demonstrated significant time- and dose-dependent inhibition by PA. PA also suppressed matrix metalloproteinase-2 (MMP-2) secretion and attenuated its activation to intermediate and active MMP-2. In addition, PA suppressed F-actin stress fiber formation to prevent migration of the endothelial cells. More importantly, anti-angiogenic potential of PA was also evidenced in two in vivo models. PA inhibited neo-vessels formation in murine Matrigel plugs, and angiogenesis in zebrafish embryos.
CONCLUSIONS/SIGNIFICANCE: Taken together, our study demonstrated the distinctive anti-angiogenic properties of PA, both in vitro and in vivo. This report thus reveals another biological activity of PA in addition to its reported anti-inflammatory and anti-cancer activities, suggestive of PA's potential for development as an anti-angiogenic agent for cancer therapy.
MATERIALS AND METHODS: Anti-cancer activity of a tocotrienol-rich fraction (TRF) and a tocotrienol-enriched fraction (TEF) isolated from palm oil, as well as pure vitamin E analogues (α-tocopherol, α-, δ- and γ-tocotrienols) were studied using highly aggressive triple negative MDA-MB-231 cells and oestrogen-dependent MCF-7 cells, both of human breast cancer cell lines. Cell population growth was evaluated using a Coulter particle counter. Cell death mechanism, poly(ADP-ribose) polymerase cleavage and levels of NF-κB were determined using commercial ELISA kits.
RESULTS: Tocotrienols exerted potent anti-proliferative effects on both types of cell by inducing apoptosis, the underlying mechanism of cell death being ascertained using respective IC50 concentrations of all test compounds. There was marked induction of apoptosis in both cell lines by tocotrienols compared to treatment with Paclitaxel, which was used as positive control. This activity was found to be associated with cleavage of poly(ADP-ribose) polymerase (a DNA repair protein), demonstrating involvement of the apoptotic cell death signalling pathway. Tocotrienols also inhibited expression of nuclear factor kappa-B (NF-κB), which in turn can increase sensitivity of cancer cells to apoptosis.
CONCLUSION: Tocotrienols induced anti-proliferative and apoptotic effects in association with DNA fragmentation, poly(ADP-ribose) polymerase cleavage and NF-κB inhibition in the two human breast cancer cell lines.
METHODS: The cytotoxicity of E. cuneatum extract was evaluated by both MTS and LDH assays. Genotoxicity study on E. cuneatum extract was assessed by the single cell gel electrophoresis (comet assay). The protective effect of E. cuneatum against menadione-induced cytotoxicity was also investigated.
RESULTS: Results from this study showed that E. cuneatum extract exhibited cytotoxic activities towards the cells with IC50 value of (125±12) and (125±14) μg/mL for HepG2 and WRL68 cells respectively, after 72 h incubation period as determined by MTS assay. LDH leakage was detected at (251±19) and (199.5±12.0) μg/mL for HepG2 and WRL68 respectively. Genotoxicity study results showed that treatment with E. cuneatum up to 1 mg/mL did not cause obvious DNA damage in WRL68 and HepG2 cells. Addition of E. cunaetum did not show significant protection towards menadione in WRL68 and HepG2 Cells.
CONCLUSIONS: E. cuneatum standardized aqueous extract might be developed in order to establish new pharmacological possibilities for its application.