{Gamma}-tocotrienol inhibits pancreatic tumors and sensitizes them to gemcitabine treatment by modulating the inflammatory microenvironment.
Pancreatic cancers generally respond poorly to chemotherapy, prompting a need to identify agents that could sensitize tumors to treatment. In this study, we investigated the response of human pancreatic cells to γ-tocotrienol (γ-T3), a novel, unsaturated form of vitamin E found in palm oil and rice bran oil, to determine whether it could potentiate the effects of gemcitabine, a standard of care in clinical treatment of pancreatic cancer. γ-T3 inhibited the in vitro proliferation of pancreatic cancer cell lines with variable p53 status and potentiated gemcitabine-induced apoptosis. These effects correlated with an inhibition of NF-κB activation by γ-T3 and a suppression of key cellular regulators including cyclin D1, c-Myc, cyclooxygenase-2 (COX-2), Bcl-2, cellular inhibitor of apoptosis protein, survivin, vascular endothelial growth factor (VEGF), ICAM-1, and CXCR4. In an orthotopic nude mouse model of human pancreatic cancer, p.o. administration of γ-T3 inhibited tumor growth and enhanced the antitumor properties of gemcitabine. Immunohistochemical analysis indicated a correlation between tumor growth inhibition and reduced expression of Ki-67, COX-2, matrix metalloproteinase-9 (MMP-9), NF-κB p65, and VEGF in the tissue. Combination treatment also downregulated NF-κB activity along with the NF-κB-regulated gene products, such as cyclin D1, c-Myc, VEGF, MMP-9, and CXCR4. Consistent with an enhancement of tumor apoptosis, caspase activation was observed in tumor tissues. Overall, our findings suggest that γ-T3 can inhibit the growth of human pancreatic tumors and sensitize them to gemcitabine by suppressing NF-κB-mediated inflammatory pathways linked to tumorigenesis.
Kunnumakkara
Ajaikumar B
AB
Department of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
Sung
Bokyung
B
Ravindran
Jayaraj
J
Diagaradjane
Parmeswaran
P
Deorukhkar
Amit
A
Dey
Sanjit
S
Koca
Cemile
C
Yadav
Vivek R
VR
Tong
Zhimin
Z
Gelovani
Juri G
JG
Guha
Sushovan
S
Krishnan
Sunil
S
Aggarwal
Bharat B
BB
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002839:Chromans / Q000494:pharmacology*; D051546:Cyclooxygenase 2 / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D006801:Humans; D007249:Inflammation / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D018836:Inflammation Mediators / Q000378:metabolism; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000276:immunology* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012264:Ribonucleotide Reductases / Q000037:antagonists & inhibitors; D014407:Tumor Cells, Cultured; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays; D000093542:Gemcitabine
D000964:Antimetabolites, Antineoplastic; D002839:Chromans; D018836:Inflammation Mediators; D016328:NF-kappa B; D012333:RNA, Messenger; D003841:Deoxycytidine; D014810:Vitamin E; C013649:plastochromanol 8; D051546:Cyclooxygenase 2; D012264:Ribonucleotide Reductases; D020780:Matrix Metalloproteinase 9; D000093542:Gemcitabine