Proliferation inhibition, DNA damage, and cell-cycle arrest of human astrocytoma cells after acrylamide exposure.
Acrylamide (ACR) has been recognized as a neurological and reproductive toxin in humans and laboratory animals. This study aimed to determine the effects of ACR-induced DNA damage on cell cycle regulation in human astrocytoma cell lines. Treatment of U-1240 MG cells with 2 mM ACR for 48 h resulted in a significant inhibition of cell proliferation as evaluated by Ki-67 protein expression and MTT assay. The analysis of DNA damage with the comet assay showed that treatment of the cells with 0.5, 1, and 2 mM ACR for 48 h caused significant increases in DNA damage by 3.5-, 4-, and 14-fold, respectively. Meanwhile, analysis of cell-cycle arrest with flow cytometry revealed that the ACR treatments resulted in significant increases in the G(0)/G(1)-arrested cells in a time- and dose-dependent manner. Expression of DNA damage-associated/checkpoint-related signaling molecules, including phosphorylated-p53 (pp53), p53, p21, p27, Cdk2, and cyclin D(1), in three human astrocytoma cell lines (U-1240 MG, U-251 MG, and U-87 MG) was also analyzed by immunoblotting. Treatment of the three cell lines with 2 mM ACR for 48 h caused marked increases in pp53 and Cdk2, as well as decreases in cyclin D(1) and p27. Moreover, increases in p53 and p21 were detected in both U-1240 and U-87 MG cells, whereas no marked change in p53 and a decrease in p21 were observed in U-251 MG cells. To address the involvement of ataxia telangiectasia mutated/ATM-Rad3-related (ATM/ATR) kinase in the signaling of ACR-induced G(0)/G(1) arrest, caffeine was used to block the ATM/ATR pathway in U-1240 MG cells. Caffeine significantly attenuated the ACR-induced G(0)/G(1) arrest as well as the expression of DNA damage-associated/checkpoint-related signaling molecules in a dose-dependent manner. This in vitro study clearly demonstrates the critical role of ATM/ATR in the signaling of ACR-induced cell-cycle arrest in astrocytoma cells.
Chen
Jong-Hang
JH
Department of Veterinary Medicine, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan.
Tsou
Tsui-Chun
TC
Chiu
Ing-Ming
IM
Chou
Chin-Cheng
CC
D020106:Acrylamide / Q000737:chemistry / Q000633:toxicity*; D001253:Astrocytes / Q000187:drug effects*; D001254:Astrocytoma; D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D020552:Comet Assay; D019938:Cyclin D1 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; D020106:Acrylamide; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases