[The methylation and mRNA expression of SLC5A8 and TMS1/ASC genes in human glioma].
OBJECTIVE
To study the methylation status of the SLC5A8 and TMS1/ASC genes, candidate tumor-inhibiting genes closely related to the central nervous system, in the promoter regions, the mRNA expression of these 2 genes, and their correlation with the clinical characteristics in human glioma.


METHODS
The methylation status of SLC5A8 and TMS1/ASC genes in the promoter regions was studied by methylation specific PCR (MSP) in the specimens of primary astrocytoma from 88 patients, 55 males and 33 females, aged 12 - 81, and 10 specimens of normal brain tissue, all obtained during operation, and in the human glioma cells of the lines U251 and SHG-44. The mRNA expression levels of SLC5A8 and TMS1/ASC genes in 30 specimens of primary glioma and 10 specimens of normal brain tissue were determined by conventional RT-PCR and real-time PCR. 5-Aza-2'-deoxycytidine (5-Aza-CdR), a demethylating agent, was added into the culture fluid of the U251 and SHG-44 cells, and then real-time PCR was used to the methylation status and mRNA expression levels of the SLC5A8 and TMS1/ASC genes.


RESULTS
MSP showed that the SLC5A8 promoter region was hypermethylated in 62 of the 88 specimens of astrocytoma (70.45%) and the TMS1/ASC promoter region was hypermethylated in 51 of the88 specimens of astrocytoma (57.95%). But no methylation of SLC5A8 and TMS1/ASC promoter was detected in the 10 specimens of normal brain tissue. The mRNA expression of SLC5A8 gene and the mRNA expression of TMS1/ASC gene in the specimens of astrocytoma of different pathological grades were all significantly decreased compared to the specimens of normal brain tissue (all P < 0.05). The mRNA expression of SLC5A8 gene was not significantly related to the age and sex, however, the mRNA expression of TMS1/ASC was significantly higher in the age group > 60 than in other age groups (all P < 0.05). Both U251 and SHG-44 glioma cells showed methylation of SLC5A8 and TMS1/ASC genes and after the treatment of 5-Aza-CdR both genes showed reactivated mRNA expression.


CONCLUSIONS
Hypermethylation of SLC5A8 and TMS1/ASC genes in the promoter regions may play an important role in the down-regulation of their mRNA levels in glioma. The methylation frequency and mRNA levels of SLC5A8 or TMS1/ASC genes are closely related to the malignant development of glioma.
Jiang
Zheng
Z
Laboratory of Neurosurgery, Qilu Hospital of Shandong University, Jinan 250012, China.
Li
Xin-gang
XG
Hu
Jin
J
Lu
Da-ru
DR
Zhou
Wei
W
Jiang
Yu-quan
YQ
Li
Chao-yue
CY
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology; D053468:CARD Signaling Adaptor Proteins; D027682:Cation Transport Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D002648:Child; D003598:Cytoskeletal Proteins / Q000235:genetics*; D019175:DNA Methylation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005910:Glioma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D027501:Monocarboxylic Acid Transporters; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D053468:CARD Signaling Adaptor Proteins; D027682:Cation Transport Proteins; D003598:Cytoskeletal Proteins; D027501:Monocarboxylic Acid Transporters; C402202:PYCARD protein, human; D012333:RNA, Messenger; C476760:SLC5A8 protein, human