Frequent epigenetic inactivation of the receptor tyrosine kinase EphA5 by promoter methylation in human breast cancer.
EphA5 is a member of the Eph receptor tyrosine kinase family, which plays a critical role in the regulation of carcinogenesis. Our previous DNA methylation microarray results suggested that the CpG islands in the EphA5 promoter exhibited higher methylation levels in breast cancer tissues. In this study, we further analyzed EphA5 gene expression profiles, methylation status, and clinical implications in breast cancer. We found that the level of EphA5 mRNA was dramatically decreased in 5 different breast cancer cell lines. After treating the cell lines with 5-aza-2'-deoxycytidine (5-aza-dC, a demethylation agent), the levels of EphA5 mRNA and protein were significantly increased. Bisulfite sequencing and methylation-specific polymerase chain reaction detection showed that decreased expression of EphA5 was associated with its methylation status. We also found a significant correlation (P = .017) between the reduction of EphA5 mRNA levels and aberrant methylation of EphA5 in 31 paired tissue samples. In clinical samples, EphA5 methylation was detected in 64.1% (75/117) of breast tumors and 28.2% (33/117) of paired normal tissues (P < .001), which was associated with higher tumor grade (P = .024), lymph node metastasis (P = .004), and progesterone receptor-negative status (P = .008). Our data indicate that EphA5 might be a potential target for epigenetic silencing in primary breast cancer and a valuable molecular marker for breast cancer carcinogenesis and progression.
Fu
De-Yuan
DY
Breast Cancer Institute, Cancer Hospital, Department of Oncology, Shanghai Medical College, Institutes of Biomedical Science, Fudan University, Shanghai 200032, PR China.
Wang
Zhi-Min
ZM
Wang
Bei-Lan
BL
Chen
Li
L
Yang
Wen-Tao
WT
Shen
Zhen-Zhou
ZZ
Huang
Wei
W
Shao
Zhi-Ming
ZM
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000378:metabolism; D001940:Breast / Q000187:drug effects / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000235:genetics* / Q000556:secondary; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000188:drug therapy / Q000235:genetics* / Q000556:secondary; D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D008875:Middle Aged; D008969:Molecular Sequence Data; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000378:metabolism; D036123:Receptor, EphA5 / Q000235:genetics*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis
D000964:Antimetabolites, Antineoplastic; D001374:Azacitidine; D014408:Biomarkers, Tumor; D000077209:Decitabine; D012333:RNA, Messenger; D036123:Receptor, EphA5; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C484173:EPHA5 protein, human