Screening of new tumor suppressor genes in sporadic colorectal cancer patients.
OBJECTIVE
The generation mechanism of colorectal cancer (CRC) has not been revealed completely, and it is believed that some unknown tumor-related genes were involved in CRC. The purpose of this study was to screen for unknown tumor suppressor genes (TSGs) in patients with sporadic CRC.


METHODS
Through loss of heterozygosity (LOH) analysis on chromosome 10 in sporadic CRC, we have found that D10S185 (10q23.31-24.33) exhibited a higher LOH frequency in our previous study. In this study, seven polymorphic microsatellite markers were chosen for refined LOH mapping of 10q23.31-24.33 in 83 Chinese patients with sporadic CRC. Based on refined LOH mapping, 51 genes were selected for the microarray-based high throughput screening which was done to identify new genes that are CRC-related. Microarray results were validated by quantitative real-time polymerase chain reaction (qRT-PCR).


RESULTS
We found that the average LOH frequency of 10q23.31-24.33 was 35.53%, and that the LOH frequency of D10S1265 correlated to Dukes stage. Through the microarray-based high throughput screening, we found 4 significant down-regulated genes: PLCE1, CPEB3, NKX2-3 and SEMA4G. And the down-regulation of PLCE1 was most significant. The results of qRT-PCR also showed that the expression of PLCE1 was at low levels in cancer tissues compared with normal tissues. It was in relative agreement with the DNA microarray data.


CONCLUSIONS
This study demonstrated that PLCE1 might be a new tumor suppressor gene related to sporadic colorectal cancer. Further studies should be done to prove it.
Wang
Xiaoliang
X
Department of General Surgery, Shanghai Jiao Tong University Affiliated First People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China.
Zbou
Chongzhi
C
Qiu
Guoqiang
G
Fan
Junwei
J
Tang
Huamei
H
Peng
Zhihai
Z
D044466:Asian People / Q000235:genetics; D002874:Chromosome Mapping; D015179:Colorectal Neoplasms / Q000235:genetics*; D018450:Disease Progression; D015536:Down-Regulation / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D019656:Loss of Heterozygosity / Q000235:genetics*; D008297:Male; D018895:Microsatellite Repeats; D054801:Phosphoinositide Phospholipase C / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D016601:RNA-Binding Proteins / Q000235:genetics; D039961:Semaphorins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
C513866:CPEB3 protein, human; D018398:Homeodomain Proteins; C534957:NKX2-3 protein, human; D016601:RNA-Binding Proteins; C405064:Sema4g protein, mouse; D039961:Semaphorins; D014157:Transcription Factors; D054801:Phosphoinositide Phospholipase C; C423320:phospholipase C epsilon