Methylation of the calcium channel-related gene, CACNA2D3, is frequent and a poor prognostic factor in gastric cancer.
OBJECTIVE
The calcium channel voltage-dependent alpha2delta subunit consists of 4 genes, CACNA2D1 to CACNA2D4, of which CACNA2D2 and CACNA2D3 are located on 3p21.3 and 3p21.1, respectively. Here, we examined the relation between alpha2delta subunit gene alterations and gastric carcinogenesis.


METHODS
The expression and methylation status of the alpha2delta subunit genes were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and methylation-specific PCR in gastric cancers (GCs). The effects of CACNA2D3 expression were examined by cell proliferation and adhesion assays, and they predicted target gene alterations.


RESULTS
Aberrant methylation of CACNA2D1 and CACNA2D3 mostly corresponded to their expression status in GC cell lines. CACNA2D1/3 methylation was detected in 10 (12.5%) and 24 (30%) of the 80 GC cases, respectively, but no CACNA2D2 methylation was seen in 32 cases. CACNA2D3 methylation was more frequently found in diffuse type than in intestinal type (16/38 [42.1%] vs 8/42 [19.0%]; P = .025) GCs. Among the 53 patients with advanced GCs, patients with cancers showing CACNA2D3 methylation had a significantly shorter survival time than patients without this methylation (P = .003). Exogenous CACNA2D3 expression strongly inhibited cell growth and adhesion and up-regulated p21 and p27 expression in HEK-293T and NUGC4 cells. Inverse effects were seen by CACNA2D3 small interfering RNA treatment in the CACNA2D3-positive cell lines, indicating that CACNA2D3 may have tumor suppressive functions.


CONCLUSIONS
Loss of CACNA2D3 expression through aberrant promoter hypermethylation may contribute to gastric carcinogenesis, and CACNA2D3 methylation is a useful prognostic marker for patients with advanced GC.
Wanajo
Aira
A
Department of Molecular Oncology, Graduate School of Medicine and Dentistry, Tokyo Medical and Dental University, Tokyo, Japan.
Sasaki
Akane
A
Nagasaki
Hiromi
H
Shimada
Shu
S
Otsubo
Takeshi
T
Owaki
Syuichi
S
Shimizu
Yasufumi
Y
Eishi
Yoshinobu
Y
Kojima
Kazuyuki
K
Nakajima
Yasuaki
Y
Kawano
Tatsuyuki
T
Yuasa
Yasuhito
Y
Akiyama
Yoshimitsu
Y
D000368:Aged; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018899:CpG Islands; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D016019:Survival Analysis; D013997:Time Factors; D014162:Transfection; D054462:p21-Activated Kinases / Q000378:metabolism
C425903:CACNA2D1 protein, human; C531012:CACNA2D3 protein, human; D015220:Calcium Channels; D050760:Cyclin-Dependent Kinase Inhibitor p27; D054462:p21-Activated Kinases; D002118:Calcium