Suppression of cFLIP by Lupeol, a Dietary Triterpene, Is Sufficient to Overcome Resistance to TRAIL-Mediated Apoptosis in Chemoresistant Human Pancreatic Cancer Cells

• Published in: Cancer research (Chicago, Ill.) Ill.), 2009-02, Vol.69 (3), p.1156-1165
• Main Authors: MURTAZA, Imtiyaz, SALEEM, Mohammad, MUSTAFA ADHAMI, Vaqar, BIN HAFEEZ, Bilal, MUKHTAR, Hasan
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic agents; Antineoplastic Combined Chemotherapy Protocols - pharmacology; Apoptosis - drug effects; Biological and medical sciences; CASP8 and FADD-Like Apoptosis Regulating Protein - antagonists & inhibitors; CASP8 and FADD-Like Apoptosis Regulating Protein - biosynthesis; CASP8 and FADD-Like Apoptosis Regulating Protein - genetics; Caspase 8 - metabolism; Cell Growth Processes - drug effects; Cell Line, Tumor; Drug Synergism; Gastroenterology. Liver. Pancreas. Abdomen; Humans; Liver. Biliary tract. Portal circulation. Exocrine pancreas; Medical sciences; Mice; Mice, Nude; Pancreatic Neoplasms - drug therapy; Pancreatic Neoplasms - genetics; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; Pentacyclic Triterpenes; Pharmacology. Drug treatments; Recombinant Proteins - pharmacology; TNF-Related Apoptosis-Inducing Ligand - administration & dosage; TNF-Related Apoptosis-Inducing Ligand - pharmacology; Transcriptional Activation - drug effects; Triterpenes - administration & dosage; Triterpenes - pharmacology; Tumors; Xenograft Model Antitumor Assays
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-08-2917

Overexpression of cellular FLICE-like inhibitory protein (cFLIP) is reported to confer chemoresistance in pancreatic cancer (PaC) cells. This study was designed to investigate the effect of lupeol, a dietary triterpene, on (a) apoptosis of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) therapy-resistant PaC cells overexpressing cFLIP and (b) growth of human pancreatic tumor xenografts in vivo. The effect of lupeol treatment on proliferation and TRAIL/caspase-8/cFLIP machinery in PaC cells was investigated. Next, cFLIP-overexpressing and cFLIP-suppressed cells were tested for sensitivity to recombinant TRAIL therapy in the presence of lupeol. Further, athymic nude mice implanted with AsPC-1 cells were treated with lupeol (40 mg/kg) thrice a week and surrogate biomarkers were evaluated in tumors. Lupeol alone treatment of cells caused (a) decrease in proliferation, (b) induction of caspase-8 and poly(ADP-ribose) polymerase cleavage, and (c) down-regulation of transcriptional activation and expression of cFLIP. Lupeol was observed to increase the TRAIL protein level in cells. Lupeol significantly decreased the viability of AsPC-1 cells both in cFLIP-suppressed cells and in cFLIP-overexpressing cells. Lupeol significantly sensitized chemoresistant PaC cells to undergo apoptosis by recombinant TRAIL. Finally, lupeol significantly reduced the growth of human PaC tumors propagated in athymic nude mice and caused modulation of cFLIP and TRAIL protein levels in tumors. Our findings showed the anticancer efficacy of lupeol with mechanistic rationale against highly chemoresistant human PaC cells. We suggest that lupeol, alone or as an adjuvant to current therapies, could be useful for the management of human PaC.