Colorectal cancer (CRC) is the third most common cancer worldwide and has poor prognosis. To identify the oncofetal proteins involved in CRC carcinogenesis, differentially expressed proteins among fetal colorectal tissues, CRC, and the paired tumor-adjacent normal colorectal tissues were investigated by a two-dimensional gel electrophoresis and MALDI-TOF/TOF-based proteomics approach. 42 protein spots were differentially expressed among these tissues, and 22 proteins were identified by MS analysis. Desmin and zinc finger protein 829 were found to be elevated in CRC tissue and fetal colorectal tissue compared with normal colorectal tissue. The elevated expression of desmin in CRC tissue and different developmental stages of fetus colon was confirmed by RT-PCR and Western blot analysis. Immunohistochemical analysis showed that the elevated expression of desmin was correlated with the severity and differentiation of CRC and decreased survival rate of CRC patients. Finally by developing a highly sensitive immunoassay, desmin could be detected in human serum and was significantly elevated in CRC patients compared with healthy volunteers. We propose that desmin be considered a potential oncofetal serum tumor marker for CRC that may have significance in the detection of patients with CRC.

The increase in proliferation and the lack of differentiation of cancer cells resemble what occur in the embryonic stem cells during physiological process of embryogenesis. There are also striking similarities in the behaviour between the invasive placental cells and invasive cancer cells. In the present study, microarrays were used to analyse the global expression of microRNAs in a human embryonic stem cell line (i.e. HUES-17) and four colorectal cancer (CRC) cell lines (i.e. LoVo, SW480, HT29 and Caco-2) with different metastatic potentialities. Only the expression of miR-26b was significant decreased in HUES-17s and LoVo cells, compared with other three cell lines (P < 0.01). The quantitative real-time PCR analysis confirmed the results of the microarray analysis. Overexpression of miR-26b expression by miR-26 mimics transfection and led to the significant suppression of the cell growth and the induction of apoptosis in LoVo cells in vitro, and the inhibition of tumour growth in vivo. Moreover, the potential targets of miR-26b was predicted by using bioinformatics, and then the predicted target genes were further validated by comparing gene expression profiles between LoVo and NCM460 cell lines. Four genes (TAF12, PTP4A1, CHFR and ALS2CR2) with intersection were found to be the targets of miR-26b. MetaCore network analysis further showed that the regulatory pathways of miR-26b were significantly associated with the invasiveness and metastasis of CRC cells. These data suggest that miR-26b might serve as a novel prognostic factor and a potential therapeutic target for CRC.

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.