Epigenetic inactivation of protein kinase D1 in gastric cancer and its role in gastric cancer cell migration and invasion.
Protein kinase D (PKD) 1 influences cell migration by mediating both trans-Golgi vesicle fission and integrin recycling to the cell surface. Using restriction landmark genomic scanning methods, we found that the promoter region of PKD1 was aberrantly methylated in gastric cancer cell lines. Silencing of PKD1 expression was detected in 72.7% of gastric cancer cell lines examined, and the silencing was associated with CpG hypermethylation in the promoter region of PKD1. Treatment with 5-aza-2'-deoxycytidine and trichostatin A partially reversed PKD1 methylation and restored gene expression in PKD1-silenced cell lines. Real-time reverse transcription-polymerase chain reaction analysis of 96 paired clinical primary gastric cancer samples revealed that 59% of the analyzed tumors had a >2-fold decrease in PKD1 expression compared with each normal-appearing tissue and that this downregulation of PKD1 expression was significantly correlated with increased methylation. We also observed a gradual increase in the level of promoter methylation of PKD1 in aging, normal-appearing mucosal tissues, suggesting that PKD1 methylation may be one of the earliest events that predispose an individual to gastric cancer. PKD1 expression was required for directional migration of gastric cancer cells. Furthermore, knock down of PKD1 by RNA interference promoted the invasiveness of cell lines that expressed PKD1 at relatively high levels. Based on these results, we propose that PKD1 is frequently silenced by epigenetic regulation, which plays a role in cell migration and metastasis in gastric cancer.
Kim
Mirang
M
Medical Genomics Research Center, KRIBB, Daejeon 305-806, Korea.
Jang
Hay-Ran
HR
Kim
Jeong-Hwan
JH
Noh
Seung-Moo
SM
Song
Kyu-Sang
KS
Cho
June-Sik
JS
Jeong
Hyun-Yong
HY
Norman
Jim C
JC
Caswell
Patrick T
PT
Kang
Gyeong Hoon
GH
Kim
Seon-Young
SY
Yoo
Hyang-Sook
HS
Kim
Yong Sung
YS
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D018899:CpG Islands; D019175:DNA Methylation; D017931:DNA Primers; D044127:Epigenesis, Genetic; D005260:Female; D020868:Gene Silencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000235:genetics*; D009362:Neoplasm Metastasis / Q000235:genetics*; D011493:Protein Kinase C / Q000235:genetics*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology*
D017931:DNA Primers; D034741:RNA, Small Interfering; C089212:protein kinase D; D011493:Protein Kinase C