HDAC inhibitors act with 5-aza-2'-deoxycytidine to inhibit cell proliferation by suppressing removal of incorporated abases in lung cancer cells.
5-Aza-2'-deoxycytidine (5-aza-CdR) is used extensively as a demethylating agent and acts in concert with histone deacetylase inhibitors (HDACI) to induce apoptosis or inhibition of cell proliferation in human cancer cells. Whether the action of 5-aza-CdR in this synergistic effect results from demethylation by this agent is not yet clear. In this study we found that inhibition of cell proliferation was not observed when cells with knockdown of DNA methyltransferase 1 (DNMT1), or double knock down of DNMT1-DNMT3A or DNMT1-DNMT3B were treated with HDACI, implying that the demethylating function of 5-aza-CdR may be not involved in this synergistic effect. Further study showed that there was a causal relationship between 5-aza-CdR induced DNA damage and the amount of [(3)H]-5-aza-CdR incorporated in DNA. However, incorporated [(3)H]-5-aza-CdR gradually decreased when cells were incubated in [(3)H]-5-aza-CdR free medium, indicating that 5-aza-CdR, which is an abnormal base, may be excluded by the cell repair system. It was of interest that HDACI significantly postponed the removal of the incorporated [(3)H]-5-aza-CdR from DNA. Moreover, HDAC inhibitor showed selective synergy with nucleoside analog-induced DNA damage to inhibit cell proliferation, but showed no such effect with other DNA damage stresses such as gamma-ray and UV, etoposide or cisplatin. This study demonstrates that HDACI synergistically inhibits cell proliferation with nucleoside analogs by suppressing removal of incorporated harmful nucleotide analogs from DNA.
Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Beijing, China.
Guolin
G
Chai
Lian
L
Li
Wen
W
Zhou
Lipeng
L
Wu
Ying
Y
Zhao
Donglai
D
Wang
Shaoli
S
Lu
Yu
Y
Yu
Haiying
H
Wang
Michael A
MA
McNutt
Ye-Guang
YG
Hu
Yingqi
Y
Chen
Yang
Y
Yang
Xin
X
Wu
Gregory A
GA
Otterson
Wei-Guo
WG
Zhu
D001374:Azacitidine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000473:pathology*; D008962:Models, Theoretical; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D000077209:Decitabine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D001374:Azacitidine