Loss of estrogen receptor-alpha expression is associated with hypermethylation near its ATG start codon in gastric cancer cell lines.
The proportion of gastric cancers positive for estrogen receptor (ER)-alpha expression is reported to be between 0-67%, depending upon the study. The role of ER-alpha in gastric carcinogenesis is unclear. The ER-alpha gene is located at chromosome 6q25.1, and the long arm of chromosome 6 has been known as a site with frequent loss of heterozygosity (LOH) in gastric cancer. ER expression is linked to suppression of cell proliferation in vitro. Epigenetic inactivation might explain the loss of ER-alpha gene expression in gastric cancer. Given there is no information available regarding the methylation status of the ER-alpha gene promoter region in gastric cancer, we investigated such methylation in 13 gastric cancer cell lines. Western blot analysis, reverse transcription-polymerase chain reaction (PCR), methylation-specific PCR (MS-PCR) and bisulfite sequencing analyses were used. ER-alpha protein was not detected in any cell line, although ER-alpha mRNA was detected in 1 of 13 gastric cancer cell lines. MS-PCR and bisulfite sequencing showed all 13 gastric cancer cell lines had methylated CpG regions in their ER-alpha gene promoters. In conclusion, inactivation of ER-alpha gene expression in gastric cancer cell lines appears associated with CpG island methylation near the TGA initiation codon of the ER-alpha gene.
Woo
In Sook
IS
Department of Internal Medicine, College of Medicine, Catholic University, Seoul 137-040, Korea. insookwoo@catholic.ac.kr
Park
Myung Jae
MJ
Choi
Seong Won
SW
Kim
Sung Joo
SJ
Lee
Myung Ah
MA
Kang
Jin Hyung
JH
Hong
Young Seon
YS
Lee
Kyung Shik
KS
D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002896:Chromosomes, Human, Pair 6; D018387:Codon, Initiator; D018899:CpG Islands; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D047628:Estrogen Receptor alpha; D020868:Gene Silencing; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011960:Receptors, Estrogen / Q000096:biosynthesis* / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics*; D013447:Sulfites / Q000494:pharmacology
D018387:Codon, Initiator; D047628:Estrogen Receptor alpha; D011960:Receptors, Estrogen; D013447:Sulfites; C009279:sodium bisulfite