Silencing SMYD3 in hepatoma demethylates RIZI promoter induces apoptosis and inhibits cell proliferation and migration.
OBJECTIVE
To investigate the role of SMYD3 in hepatocellular carcinoma (HCC) development and progression and to verify whether its regulation activity was through RIZ1 inactivation.


METHODS
Expression of SMYD3 in HCC cell lines and tissues were measured; silencing of SMYD3 by RNA interference (RNAi) was effectuated, hepatoma cell proliferation, migration and apoptosis were tested, with RIZ1 CpG promoter methylation, and corresponding mRNA expression were investigated.


RESULTS
SMYD3 over-expression in HCC was associated with RIZ1 hypermethylation and mRNA down-expression. Suppression of SMYD3 expression de-methylated RIZ1 CpG promoter (P < 0.01) and increased RIZ1 mRNA expression (P < 0.01). Consequently, SMYD3 down-expression with RIZ1 de-methylation strongly inhibited hepatoma cell growth (MTT inhibitory rates: Pgenesil-1-s1 60.95% +/- 7.97%, Pgenesil-1-s2 72.14% +/- 9.68% vs Pgenesil-1-hk 6.89% +/- 4.12%, P < 0.01) and migration (Pgenesil-1-s1 4.24% +/- 1.58%, Pgenesil-1-s1 4.87% +/- 0.73% vs Pgenesil-1 19.03% +/- 4.63%, Pgenesil-1-hk 19.95% +/- 5.21%, P < 0.01) and induced apoptosis (FCM subG1 phase Pgenesil-1-s1 19.07% +/- 1.78%, Pgenesil-1-s2 17.68% +/- 2.36% vs Pgenesil-1 0.47% +/- 0.12%, Pgenesil-1-hk 1.46% +/- 0.28%, P < 0.01. TUNEL-positive cells: Pgenesil-1-s1 40.24% +/- 5.18%, Pgenesil-1-s2 38.48% +/- 4.65% vs Pgenesil-1 2.18% +/- 1.34%, Pgenesil-1-hk 2.84% +/- 1.22%, P < 0.01) in HepG2 cells.


CONCLUSIONS
These results demonstrate that SMYD3 plays a critical role in the carcinogenesis and progression of HCC. The proliferation, migration induction and apoptosis inhibition activities of SMYD3 may be mediated through RIZ1 CpG promoter hypermethylation.
Chen
Li-Bo
LB
Hepatobiliary center, Union Hospital of Huazhong University of Science and Technology, Wuhan 430022, Hubei province, China. libo_chen@hotmail.com
Xu
Jun-Yao
JY
Yang
Zhen
Z
Wang
Guo-Bin
GB
D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects; D004273:DNA, Neoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; D011495:Histone-Lysine N-Methyltransferase; C093563:PRDM2 protein, human; C506278:SMYD3 protein, human