Regulation of DR-5 protein and mitochondrial transmembrane potential by gemcitabine, a possible mechanism of gemcitabine-enhanced TRAIL-induced apoptosis.
Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family and a potent inducer of apoptosis. Gemcitabine, chemotherapeutic agent is well known to be involved in synergistic cytotoxic effect with TRAIL. But the mechanism of this synergistic effect is still unclear. To examine the effects and synergistic mechanism of gemcitabine on TRAIL-induced apoptosis, A549, HCT116 and SNU638 cells were pretreated with gemcitabine and treated with TRAIL protein. Gemcitabine significantly enhanced A549 cell death induced by TRAIL, but it was inhibited by the pan-caspase inhibitor, Z-VAD-fmk. The combined treatment of both induced the activation of caspase-8 and reduced the mitochondrial transmembrane potential (MTP) and also translocated Bax protein and released the cytochrome-c in A549 cells when compared with that of negative control. In addition, the gemcitabine pretreatment up-regulated DR-5 and p53 protein expression in a time-dependent manner, which suggests the possible involvement of the p53 protein as a transcriptional factor for DR-5 up-regulation. Thus, we report our findings that gemcitabine enhanced the TRAIL-induced apoptosis and the apoptotic signals are mediated by DR-5-dependent pathway and mitochondrial pathway. Taken together, gemcitabine enhanced TRAIL-induced apoptosis via DR-5 up-regulation and lowering MTP, and suggest that gemcitabine may be used as a successful chemotherapeutic agent for ligand type tumor therapy combined with TRAIL.
Center for Healthcare Technology Development, College of Veterinary Medicine, Chonbuk National University, Jeonju, Jeonbuk, South Korea.
Jae-Won
JW
Seol
Atul A
AA
Chaudhari
You-Jin
YJ
Lee
Hyung-Sub
HS
Kang
In-Shik
IS
Kim
Nam-Soo
NS
Kim
Jin-Ho
JH
Park
Tae-Hyung
TH
Kim
Dai-Wu
DW
Seol
Sang-Youel
SY
Park
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms; D053938:DNA Fragmentation; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005770:Gastrointestinal Neoplasms; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms; D008564:Membrane Potentials / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D000093542:Gemcitabine
D000964:Antimetabolites, Antineoplastic; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D003841:Deoxycytidine; D000093542:Gemcitabine