hMTH1 depletion promotes oxidative-stress-induced apoptosis through a Noxa- and caspase-3/7-mediated signaling pathway.
Although the accumulation of 8-oxo-dGTP in DNA is associated with apoptotic cell death and mutagenesis, little is known about the exact mechanism of hMTH1-mediated suppression of oxidative-stress-induced cell death. Therefore, we investigated the regulation of DNA-damage-related apoptosis induced by oxidative stress using control and hMTH1 knockdown cells. Small interfering RNA (siRNA) was used to suppress hMTH1 expression in p53-proficient GM00637 and H460 cells, resulting in a significant increase in apoptotic cell death after H(2)O(2) exposure; however, p53-null, hMTH1-deficient H1299 cells did not exhibit H(2)O(2)-induced apoptosis. In addition, hMTH1-deficient GM00637 and H460 cells showed increased caspase-3/7 activity, cleaved caspase-8, and Noxa expression, and gamma-H2AX formation in response to H(2)O(2). In contrast, the caspase inhibitors, p53-siRNA, and Noxa-siRNA suppressed H(2)O(2)-induced cell death. Moreover, in 8-week (long-term) cultured H460 and H1299 cells, hMTH1 suppression increased cell death, Noxa expression, and gamma-H2AX after H(2)O(2) exposure, compared to 3-week (short-term) cultured cells. These data indicate that hMTH1 plays an important role in protecting cells against H(2)O(2)-induced apoptosis via a Noxa- and caspase-3/7-mediated signaling pathway, thus conferring a survival advantage through the inhibition of oxidative-stress-induced DNA damage.
Youn
Cha-Kyung
CK
DNA Repair Research Center, Chosun University, 375 Seosuk-dong, Gwangju, Republic of Korea.
Jun
Jae Yeoul
JY
Hyun
Jin-Won
JW
Hwang
Gul
G
Lee
Byoung Rai
BR
Chung
Myung Hee
MH
Chang
In-Youb
IY
You
Ho Jin
HJ
D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism*; D053179:Caspase 7 / Q000378:metabolism*; D045744:Cell Line, Tumor; D020552:Comet Assay; D045643:DNA Repair Enzymes / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008954:Models, Biological; D018384:Oxidative Stress; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
C498702:PMAIP1 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D006861:Hydrogen Peroxide; D010744:Phosphoric Monoester Hydrolases; D053148:Caspase 3; D053179:Caspase 7; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes