Reactive oxygen species up-regulate p53 and Puma; a possible mechanism for apoptosis during combined treatment with TRAIL and wogonin.
OBJECTIVE
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) triggers apoptotic death in a variety of cancer cells without marked toxicity to most normal cells. We previously reported that wogonin, a potent anticancer agent from a Chinese herb, up-regulates p53 in prostate cancer cells. In this study, the effects of combinations of TRAIL and wogonin on a human prostate cancer cell line LNCaP, resistant to TRAIL, was evaluated for evidence of synergy in triggering apoptosis.


METHODS
Western blot assay and the 'comet' assay were used to study the underlying mechanisms of cell death and search for any mechanisms of enhancement of TRAIL-induced apoptosis in the presence of wogonin.


RESULTS
During combined treatment with wogonin and TRAIL, cytotoxicity, poly(ADP-ribose) polymerase cleavage and caspase activation were associated with up-regulation of p53 through DNA damage and reactive oxygen species (ROS) generation. N-acetylcysteine (NAC), an antioxidant, inhibited ROS generation and synergistic interaction between TRAIL and wogonin. Experimental results in human colon cancer HCT116 cells demonstrated that p53-dependent Puma up-regulation played an important role; deficiency in either p53 or Puma prevented wogonin-enhanced TRAIL-induced apoptosis.


CONCLUSIONS
The present studies suggest that wogonin enhances TRAIL-induced cytotoxicity through up-regulation of p53 and Puma, mediated by ROS.
Department of Surgery and Pharmacology, School of Medicine, University of Pittsburgh, Hillman Cancer Center, 5117 Centre Avenue, Pittsburgh, PA 15213, USA.
Dae-Hee
DH
Lee
Juong G
JG
Rhee
Yong J
YJ
Lee
D000970:Antineoplastic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis* / Q000235:genetics; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004249:DNA Damage; D004357:Drug Synergism; D004789:Enzyme Activation; D044950:Flavanones / Q000494:pharmacology*; D055785:Gene Knockdown Techniques; D006657:Histones / Q000378:metabolism; D006801:Humans; D008297:Male; D010766:Phosphorylation; D011471:Prostatic Neoplasms; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000502:physiology
D000970:Antineoplastic Agents; D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; C494826:BAX protein, human; C438378:BBC3 protein, human; D044950:Flavanones; C468783:H2AX protein, human; D006657:Histones; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D020169:Caspases; C085514:wogonin