Modulation of E-cadherin expression by K-Ras; involvement of DNA methyltransferase-3b.
E-cadherin, as a tumor suppressor, plays an important role for intercellular adhesion involved in metastasis. Although K-Ras is highly expressed in a variety of cancers, the regulation of E-cadherin expression by K-Ras in association with DNA methylation and cell metastasis has not been completely clarified. In this study, E-cadherin expression was repressed in 267B1/K-Ras human epithelial prostate cancer cells stably overexpressing K-Ras, resulting from hypermethylation of E-cadherin promoter as evidenced by methylation-specific polymerase chain reaction (PCR), bisulfite sequencing, real-time reverse transcription-PCR and western blot analysis. The increased level of DNA methyltransferase (DNMT) 3b in 267B1/K-Ras cells was reduced by small interfering RNA-mediated knockdown of k-ras, whereas DNMT1 and DNMT3a did not change regardless of K-Ras or 5-aza-2'-deoxycytidine (5'-AzaC) treatment. Furthermore, binding of DNMT3b to E-cadherin promoter was increased in 267B1/K-Ras cells but was reduced by 5'-AzaC, as revealed by chromatin immunoprecipitation assay, which was in agreement with cell aggregation and invasive mobilization of the cells. Hence, our data suggest that increased binding of DNMT3b to E-cadherin promoter region by K-Ras cause promoter hypermethylation for reduced expression of E-cadherin, leading to the decreased cell aggregation and increased metastasis of human prostate cancer cells overexpressing K-Ras.
Kwon
Osong
O
Korea Research Institute Yangcheong-Ri, Ochang, Chungbuk 363-883, Korea.
Jeong
Sook Jung
SJ
Kim
Sun Ok
SO
He
Long
L
Lee
Hee Gu
HG
Jang
Kyung Lib
KL
Osada
Hiroyuki
H
Jung
Mira
M
Kim
Bo Yeon
BY
Ahn
Jong Seog
JS
D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D015820:Cadherins / Q000235:genetics*; D002450:Cell Communication; D045744:Cell Line, Tumor; D002465:Cell Movement; D018899:CpG Islands; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000502:physiology*; D019175:DNA Methylation; D000077209:Decitabine; D011905:Genes, ras; D006801:Humans; D008297:Male; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000473:pathology*; D000097584:DNA Methyltransferase 3B
D001374:Azacitidine; D015820:Cadherins; D004248:DNA (Cytosine-5-)-Methyltransferases; D000077209:Decitabine; D000097584:DNA Methyltransferase 3B