Aberrant methylation and downregulation of sall3 in human hepatocellular carcinoma.
OBJECTIVE
To investigated whether sall3 transcription was regulated by promoter CpG island hypermethylation in hepatocellular carcinoma (HCC).


METHODS
The cell lines Huh7, HepG2, SK-HEP1, SMMC7721, Bel7402, QGY7703 and a cohort of 38 HCC tissue specimens and corresponding nontumorous tissues were subjected to analysis for sall3 promoter CpG island methylation and mRNA transcription. sall3 promoter CpG island methylation levels were determined using the MassARRAY platform and mRNA transcription levels of the gene were detected by quantitative real-time polymerase chain reaction.


RESULTS
The levels of sall3 mRNA were decreased by more than twofold in 33 of 38 tumor tissues compared to adjacent noncancerous tissues. Among these 33 tumor tissues with lower levels of sall3 mRNA, 24 showed higher levels of methylation. Based on these results, we hypothesized that the decrease in sall3 mRNA transcription level was likely due to promoter CpG island hypermethylation. Changes in sall3 mRNA transcription and promoter CpG island methylation were determined in the above six cell lines after treatment with 0, 0.1, 0.5 and 2.5 μmol 5-aza-2-deoxycytidine, a demethylating agent. Promoter CpG island methylation levels decreased in a dose-dependent manner in all six cell lines, while the mRNA transcription level increased dose-dependently in Huh7, HepG2, SK-HEP1 and SMMC7721 cells and irregularly in Bel7402 and QGY7703 cells.


CONCLUSIONS
These results indicated that promoter CpG island hypermethylation contributes to the downregulation of sall3 mRNA transcription in HCC.
School of Biotechnology, Southern Medical University, Guangzhou 510515, Guangdong Province, China.
Xue-Xi
XX
Yang
Jing-Zhe
JZ
Sun
Fen-Xia
FX
Li
Ying-Song
YS
Wu
Hong-Yan
HY
Du
Wei
W
Zhu
Xiang-Hong
XH
Li
Ming
M
Li
D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism*; D008957:Models, Genetic; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics*; D014158:Transcription, Genetic
D018398:Homeodomain Proteins; D012333:RNA, Messenger; C484466:SALL3 protein, human; D014157:Transcription Factors; D000077209:Decitabine; D001374:Azacitidine