[Genome DNA hypomethylation in the process of crystalline nickel-induced cell malignant transformation].
OBJECTIVE
To observe the effect of crystalline NiS on genome DNA methylation profile in in vitro cultured cells.


METHODS
16HBE Cells were treated with crystalline NiS at 0.25, 0.50, 1.00 and 2.00 µg/cm(2) for 24 h and three times at total. DAC treatment was given at 3 µmol/L for 72 h.5-mC immunofluorescence and SssI methyltransferase assay methods were applied to investigate if the hypomethylation of genome DNA involved.


RESULTS
The results of 5-mC immunofluorescence showed that the fluorescence intensity of NiS-treated cells were decreased in some degree, and transformed cells were decreased dramatically. By the SssI methylase assay, an average of (81.9 ± 7.3)% methylated CpG were found in negative control cells. By contrast, (77.9 ± 6.2)%, (75.3 ± 6.8)%, (59.5 ± 4.9)%, (67.4 ± 5.1)% methylated CpG were observed in cells treated with NiS for three times at dosage of 0.25, 0.50, 1.00 and 2.00 µg/cm(2) which were abbreviated as NiS0.25, NiS0.50, NiS1.00, NiS2.00 respectively. The ANOVA analysis results showed that there was a significant difference in the 5 groups above (F = 124.95, P < 0.01). The results of Dunnett-t test showed that the methylated CpG of both group NiS1.00 and NiS2.00 were significantly decreased compared with the negative control group (t values were 7.64, 4.89 respectively, P < 0.01). For methylated CpG, (46.2 ± 4.1)% and (43.6% ± 4.3)% were observed in NiS-transformed cells (NSTC1 and NSTC2) which were dramatically decreased compared with the negative control group (t values were 12.79, 13.56 respectively, P < 0.01).


CONCLUSIONS
Genomic DNA methylation levels were decreased during NiS induced malignant transformation.
Toxicology Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen 518020, China.
Lin-qing
LQ
Yang
Wei-dong
WD
Ji
Gong-hua
GH
Tao
Wen-juan
WJ
Zhang
Chun-mei
CM
Gong
Li
L
Zhou
Jian-jun
JJ
Liu
Yue-bin
YB
Ke
Zhi-xiong
ZX
Zhuang
D001980:Bronchi / Q000166:cytology; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D019175:DNA Methylation / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects*; D016678:Genome; D006801:Humans; D009532:Nickel / Q000009:adverse effects* / Q000737:chemistry
D009532:Nickel