Colorectal cancer (CRC) is the third most common
cancer worldwide and has poor prognosis. To identify the
proteins involved in colorectal
carcinogenesis, we employed 2-DE and MALDI-TOF/TOF-based proteomics approach to study the differentially expressed
proteins in
tumor and adjacent nontumor tissue samples. Samples from 10 colorectal patients were analyzed. Of the 7 significantly and consistently altered
proteins identified,
hnRNP A1 was one of the most significantly altered
proteins and its overexpression was confirmed using RT-PCR and Western blot analyses. Immunohistochemical examination showed that the enhanced expression of
hnRNP A1 was correlated with the increasing severity of colorectal tissue and the progression of the
colorectal cancer, as well as UICC (International Union against
Cancer) staging, histo-differentiation, recurrence and decreased survival. By developing a highly sensitive immunoassay,
hnRNP A1 could be detected in human serum and was significantly elevated in CRC patients compared with healthy volunteers. We proposed that
hnRNP A1 could be considered as a novel serum
tumor marker for CRC that may have significance in the detection and in the management of patients with this disease. Knockdown of
hnRNP A1 expression by RNA interference led to the significant suppression of the cell growth in
colorectal cancer SW480 cells in vitro. These data suggested that
hnRNP A1 may be a potential
biomarker for early diagnosis, prognosis, and monitoring in the
therapy of
colorectal cancer. Further studies are needed to fully assess the potential clinical value of this
biomarker candidate.