[Correlation of the methylation status of CpG islands in the promoter region of 10 genes with the 5-Fu chemosensitivity in 3 breast cancer cell lines].
OBJECTIVE
To explore the relationship between the methylation status of CpG islands in the promoter region of 10 genes in breast cancer cells and their sensitivity to 5-fluouracil (5-Fu), and to identify the genes responsible for the 5-Fu resistance in breast cancer.


METHODS
Three cell lines (differently resistant to chemotherapy) were used in this study: Bcap-37 (IC(50): 289.77 microg/ml), T47D (IC(50): 134.16 microg/ml) and ZR-75-30 (IC(50): 4.20 microg/ml). The methylation profile of 10 genes (BAG1, C11ORF31, CBR1, CBR4, GJA1, FOXL2, IGFBP6, P4HA1, SRI and TYMS) in the 3 breast cancer cell lines was determined by methylation specific PCR. The steady-state mRNAs of ABCC8, CHFR and IGFBP6 genes were quantified by real-time RT PCR analysis.


RESULTS
Among the 10 genes, only genes IGFBP6 and FOXL2 displayed differential DNA methylation pattern between the 5-Fu-resistant and 5-Fu-sensitive cell lines. The mRNA expression level of genes PRSS21, LOX, IGFBP6, ABCC8 and CHFR was quantified by real-time RT-PCR analysis. Except for CHFR, the expression level of the other 4 genes was correlated with the methylation status of CpG islands, namely, a lower expression level with methylation status and a higher level with demethylation status.


CONCLUSIONS
The results of the present study have demonstrated that there are 8 genes with differential methylation status in chemosensitive and chemoresistant breast cancer cell lines, i.e. two genes more than the six genes we reported previously. Our findings provide both mechanistic insights for the drug resistance of breast cancer and the basis for further studies on potential application of the DNA methylation in this set of genes for prediction of chemosensitivity of breast cancer.
Zhou
Xiao-yu
XY
Fudan University School of Medicine, Shanghai 200032, China.
Sun
Jin-feng
JF
He
Ying-hua
YH
Zhang
Hong-yu
HY
Yu
Jian
J
Guo
Shi-cheng
SC
Cai
Yang
Y
Hu
Xi-chun
XC
Zhu
Jing-de
JD
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation; D019008:Drug Resistance, Neoplasm; D005472:Fluorouracil / Q000494:pharmacology; D000074842:Forkhead Box Protein L2; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018976:Insulin-Like Growth Factor Binding Protein 6 / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism
D000964:Antimetabolites, Antineoplastic; C421604:FOXL2 protein, human; D000074842:Forkhead Box Protein L2; D051858:Forkhead Transcription Factors; D018976:Insulin-Like Growth Factor Binding Protein 6; D012333:RNA, Messenger; D005472:Fluorouracil