Relation of promoter methylation of mdr-1 gene and histone acetylation status with multidrug resistance in MCF-7/Adr cells.
OBJECTIVE
To analyze the mdr-1 gene promoter methylation and histone acetylation status in both MCF-7/Adr and MCF-7 cells and to preliminarily explore the epigenetic mechanism of multidrug resistance in breast cancer.


METHODS
mdr-1 gene promoter methylation status of the 2 cell lines was detected by methylation-sensitive PCR. mRNA expression of DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) was detected by real-time quantitative PCR. Acetylation level of histone H3 and H4 was examined by optical density assay.


RESULTS
Promoter hypermethylation of mdr-1 gene was observed in MCF-7 cells whereas hypomethylation was found in MCF-7/Adr cells. Expression of DNMT1, DNMT3a, and DNMT3b mRNA in MCF-7/Adr cells significantly decreased compared with that of MCF-7 cells (P<0.05). H3 and H4 histone acetylation levels of MCF-7/Adr cells were obviously higher than those of the MCF-7 cells (P<0.01). Expression of HDAC1, HDAC2, HDAC7, and Sirtuin type 1 (SIRT1) mRNA in MCF-7/Adr cells was significantly reduced (P<0.05).


CONCLUSIONS
Hypomethylation of the promoter region of mdr-1 gene, high H3 and H4 histone acetylation, and low mRNA expression of DNMTs and HDACs may be important epigenetic factors for the development of MDR in MCF-7/ Adr cells.
Huang
Chenghui
C
Department of Oncology, Third Xiangya Hospital, Central South University, Changsha 410013, China. hchdoctor@sohu.com
Cao
Peiguo
P
Xie
Zhaoxia
Z
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D000107:Acetylation; D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D044127:Epigenesis, Genetic; D005260:Female; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000737:chemistry; D006801:Humans; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D006657:Histones; D012333:RNA, Messenger; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D006655:Histone Deacetylases