Vitamin E δ-Tocotrienol Augments the Anti-tumor Activity of Gemcitabine and Suppresses Constitutive NF-κB Activation in Pancreatic Cancer
Menée in vitro et in vivo, cette étude montre que le tocotriénol delta, une forme insaturée de la vitamine E, augmente l'activité antitumorale de la gemcitabine et inhibe l'activité du facteur nucléaire Kappa-B dans le cancer du pancréas
The nuclear factor-κB (NF-κB) transcription factor functions as a crucial regulator of cell survival and chemoresistance in pancreatic cancer. Recent studies suggest that tocotrienols, which are the unsaturated forms of vitamin E, are a promising class of anti-cancer compounds that inhibit the growth and survival of many cancer cells, including pancreatic cancer. Here, we show that tocotrienols inhibited NF-κB activity and the survival of human pancreatic cancer cells in vitro and in vivo. Importantly, we found the bioactivity of the 4 natural tocotrienol compounds (α-, β-, δ-, and γ-tocotrienol) to be directly related to their ability to suppress NF-κB activity in vitro and in vivo. The most bioactive tocotrienol for pancreatic cancer, δ-tocotrienol, significantly enhanced the efficacy of gemcitabine to inhibit pancreatic cancer growth and survival in vitro and in vivo. Moreover, we found that δ-tocotrienol augmentation of gemcitabine activity in pancreatic cancer cells and tumors is associated with significant suppression of NF-κB activity and the expression of NF-κB transcriptional targets [Bcl-XL, X-linked inhibitor of apoptosis (XIAP), and survivin]. Our study represents the first comprehensive pre-clinical evaluation of the activity of natural vitamin E compounds in pancreatic cancer. Given these results, we are conducting a phase I trial of δ-tocotrienol in patients with pancreatic cancer utilizing pancreatic tumor cell survival and NF-κB signaling components as intermediate biomarkers. Our data also support future clinical investigation of δ-tocotrienol to augment gemcitabine activity in pancreatic cancer.
http://mct.aacrjournals.org/content/early/2011/10/04/1535-7163.MCT-11-0424.abstract