Down-regulation of poly (ADP-ribose) polymerase 1 leads to change of hydroquinone cytotoxicity in TK6 cells.
Hydroquinone (HQ), one of the most important metabolites derived from benzene, is known to be associated with acute myelogenous leukemia risk; however, its carcinogenic mechanism remains unclear. In a previous study, we found that low-level of benzene exposure down-regulated the expression of poly(ADP-ribose)polymerase 1 (PARP1). Here, we employed RNA interference to knock down PARP1 expression in TK6 cells and explored the potential role of PARP1 in HQ-induced cytotoxicity. The results showed that stable PARP1-knockdown cells were successfully constructed and more than 80% inhibition of PARP1 expression was confirmed. We found that HQ treatment of TK6 cells decreased cell viability, increased cell apoptosis, and caspase3/7 activity. Knockdown of PARP1 in HQ-treated TK6 cells prevented caspase3 activation, and increased apoptosis than that in the wild-type TK6 cells, with fully functional PARP1. The results also showed that down-regulation of PARP1 led to a decrease in cell proliferation and an enhanced susceptibility to HQ-induced cytotoxicity with concentration less than 40 μM than that in normal TK6 cells. Moreover, PARP1-knockdown TK6 cells treated with HQ displayed an increased level of DNA double-strand breaks as measured by olive tail moment. No evidence was obtained of an effect of PARP1 depletion on H2AX phosphorylation induction. Under the experimental conditions, PARP1 has a role in HQ-induced DNA damage repair rather than in long-term chromatin modifications signaled by phosphorylated H2AX.
a Department of Education and Research .
Yan
Y
Sha
b Department of Occupational Hazard Assessment .
Wei
W
Zhou
b Department of Occupational Hazard Assessment .
Zhenyu
Z
Yang
b Department of Occupational Hazard Assessment .
Xiaoling
X
Zhu
a Department of Education and Research .
Xinyue
X
Yang
c Physicochemical Laboratory , and.
Tian-di
TD
Li
d Department of Integrated Services , Shenzhen Prevention and Treatment Center for Occupational Diseases , Shenzhen , Guangdong , China.
Dexiang
D
Zhu
D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D053179:Caspase 7 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006657:Histones / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000633:toxicity*; D010766:Phosphorylation; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection
C468783:H2AX protein, human; D006657:Histones; D006873:Hydroquinones; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; C031927:hydroquinone
Apoptosis; DNA damage; hydroquinone; poly (ADP-ribose) polymerase-1; short hairpin RNAs