Snake venom toxin from Vipera lebetina turanica induces apoptosis of colon cancer cells via upregulation of ROS- and JNK-mediated death receptor expression.
BACKGROUND
Abundant research suggested that the cancer cells avoid destruction by the immune system through down-regulation or mutation of death receptors. Therefore, it is very important that finding the agents that increase the death receptors of cancer cells. In this study, we demonstrated that the snake venom toxin from Vipera lebetina turanica induce the apoptosis of colon cancer cells through reactive oxygen species (ROS) and c-Jun N-terminal kinases (JNK) dependent death receptor (DR4 and DR5) expression.


METHODS
We used cell viability assays, DAPI/TUNEL assays, as well as western blot for detection of apoptosis related proteins and DRs to demonstrate that snake venom toxin-induced apoptosis is DR4 and DR5 dependent. We carried out transient siRNA knockdowns of DR4 and DR5 in colon cancer cells.


RESULTS
We showed that snake venom toxin inhibited growth of colon cancer cells through induction of apoptosis. We also showed that the expression of DR4 and DR5 was increased by treatment of snake venom toxin. Moreover, knockdown of DR4 or DR5 reversed the effect of snake venom toxin. Snake venom toxin also induced JNK phosphorylation and ROS generation, however, pretreatment of JNK inhibitor and ROS scavenger reversed the inhibitory effect of snake venom toxin on cancer cell proliferation, and reduced the snake venom toxin-induced upregulation of DR4 and DR5 expression.


CONCLUSIONS
Our results indicated that snake venom toxin could inhibit human colon cancer cell growth, and these effects may be related to ROS and JNK mediated activation of death receptor (DR4 and DR5) signals.
College of Pharmacy and Medical Research Center, Chungbuk National University, 12 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk, 361-763, South Korea.
Mi Hee
MH
Park
MiRan
M
Jo
Dohee
D
Won
Ho Sueb
HS
Song
Sang Bae
SB
Han
Min Jong
MJ
Song
Jin Tae
JT
Hong
D000704:Analysis of Variance; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D015153:Blotting, Western; D020169:Caspases / Q000008:administration & dosage / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy*; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D017382:Reactive Oxygen Species; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D015854:Up-Regulation; D014757:Viper Venoms / Q000494:pharmacology*
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D017382:Reactive Oxygen Species; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D014757:Viper Venoms; D048031:JNK Mitogen-Activated Protein Kinases; D020169:Caspases