The inhibitory effect of CdCl2 on DNA mismatch repair activity in ZR75-1 cells
1.School of Public Health and Environment, Wenzhou Medical University, Wenzhou, 325035; 2.Laboratory Center, Ophthalmology and Eye Hospital Affiliated to Wenzhou Medical University, Wenzhou, 325027
LIU Xiaojuan1,CHEN Yuanhong1,LIU Ya2, et al. The inhibitory effect of CdCl2 on DNA mismatch repair activity in ZR75-1 cells[J]. JOURNAL OF WEZHOU MEDICAL UNIVERSITY, 2015, 45(11): 791-.
Abstract：Objective: To study the effects of CdCl2 on the DNA mismatch repair (DNA MMR) activity in human breast cancer cells ZR75-1. Methods: MTT assay was used to detect the survival rate of ZR75-1 cells exposed 48 and 72 h to 0, 10, 20, 30, 40, 50 µmol/L CdCl2. The cells from 5, 10, 15 µmol/L CdCl2 exposure (48 h) and control group were parallelly transfected with homoduplex and heteroduplex plasmids, flow cytometry analysis was then carried out to quantitatively measure the relative EGFP expression (indirectly reflected DNA MMR activity) in ZR75-1 cells of each groups. Meanwhile, real-time fluorescent quantitative PCR technique was used to detect the mRNA expression of DNA MMR related genes (MLH1, MSH2, MSH6 and PMS1) after exposure 48 h to 5, 10, 15 µmol/L CdCl2. Results: 10, 20 µmol/L CdCl2 exhibited no influence on ZR75-1 cell survival (P>0.05), while cells exposed to 30, 40 and 50 µmol/L CdCl2 displayed significant mortality which showed obvious dose-dependent and time-dependent manner (P<0.05). Compared with control group, 5, 10 and 15 µmol/L CdCl2 exposure induced significant inhibition of DNA MMR activity in ZR75-1 cells (P<0.05). Real-time PCR results showed that after exposure to 5, 10 and 15 µmol/L CdCl2 for 48 h, the mRNA expression of detected genes (MLH1, MSH2, MSH6 and PMS1) was increased as a whole, which presented down after rising first with CdCl2 exposure concentration increase. Conclusion: Low dose of CdCl2 exposure which showed no effect on cell survival can represse DNA MMR activity in ZR75-1 cells, and up-regulate the mRNA expression of DNA MMR related genes.
[1] Huff J, Lunn RM, Waalkes MP, et al. Cadmium-induced cancers in animals and in humans[J]. Int J Occup Environ Health, 2007, 13(2): 202-212.
[2] Jin YH, Clark AB, Slebos RJ, et al. Cadmium is a mutagen that acts by inhibiting mismatch repair[J]. Nat Genet, 2003,34(3): 326-329.
[3] Peltomäki P. DNA mismatch repair and cancer[J]. Mutat Res, 2001, 488(1): 77-85.
[4] Lei X, Zhu Y, Tomkinson A, et al. Measurement of DNA mismatch repair activity in live cells[J]. Nucleic Acids Res,2004, 32(12): e100.
[5] Zhou B, Huang C, Yang J, et al. Preparation of heteroduplex enhanced green fluorescent protein plasmid for in vivo mismatch repair activity assay[J]. Anal Biochem, 2009, 388(1):167-169.
[6] Zhou B, Dong Q, Ma R, et al. Rapid isolation of highly pure single-stranded DNA from phagemids[J]. Anal Biochem, 2009, 389(2): 177-179.
[7] Kunkel TA, Erie DA. DNA mismatch repair[J]. Annu Rev Biochem, 2005, 74: 681-710.
[8] 刘卓, 吴建新. DNA错配修复系统组成和功能的研究进展[J]. 现代生物医学进展, 2008, 8: 1160-1165.
[9] Lützen A, Liberti SE, Rasmussen LJ. Cadmium inhibits human DNA mismatch repair in vivo[J]. Biochem Biophys Res Commun, 2004, 321(1): 21-25.
[10] Chen Y, Huang C, Bai C, et al. Benzo [α] pyrene repressed DNA mismatch repair in human breast cancer cells[J]. Toxicology, 2013, 304(2): 167-172.
[11] Wieland M, Levin MK, Hingorani KS, et al. Mechanism of cadmium-mediated inhibition of Msh2-Msh6 function in DNA mismatch repair[J]. Biochemistry, 2009, 48(40): 9492-9502.
