Deletion and down-regulation of SMAD4 gene in colorectal cancers in a Chinese population.
OBJECTIVE
Colorectal cancer (CRC) is one of the most common types of human cancers. As a tumor suppressor, SMAD4 plays a key role in colorectal carcinogenesis and invasiveness. Copy number variations (CNVs) of the SMAD4 gene have been reported to be associated with cancer pathogenesis in array-based studies in different populations. Here we aimed to investigate the CNVs of the SMAD4 gene in a relatively large number of CRC patients from China.


METHODS
In the present study, we collected 147 Chinese CRC tumors as well as self-paired normal control tissues. Quantitative PCR was carried out to examine the copy number as well as the mRNA expression of the SMAD4 gene.


RESULTS
Our results showed that the copy number deletions of SMAD4 were frequent in a relatively high percentage of CRC samples (34.7%, 51 out of 147). There was a positive correlation between the copy number decrease of SMAD4 and tumor progression in CRCs. Furthermore, copy number loss of SMAD4 was correlated with decreased mRNA expression.


CONCLUSIONS
These findings suggested that the copy number deletions of SMAD4 were frequent in CRC patients from China and had the potential to serve as a diagnostic indicator, alone or in combination with other markers, for CRC.
Department of Oncology, Zhongshan Hospital, Wuhan University, Wuhan 430033, China.
Yanling
Y
Ma
Department of Oncology, Zhongshan Hospital, Wuhan University, Wuhan 430033, China.
Fei
F
Yan
Department of Oncology, Zhongshan Hospital, Wuhan University, Wuhan 430033, China.
Li
L
Li
Department of Oncology, Zhongshan Hospital, Wuhan University, Wuhan 430033, China.
Li
L
Liu
Department of Oncology, Zhongshan Hospital, Wuhan University, Wuhan 430033, China.
Jianhai
J
Sun
Colorectal cancer (CRC); SMAD4; copy number variation (CNV); gene expression