The objective of this study was to evaluate the frequency of CD133 expression in colorectal cancer, the distribution of CD133-positive cancer cells, and their relationship to clinicopathological features, including survival.
The great majority of the cells expressing CD133 also expressed gastrin precursors in both DLD-1 cells, which retain a stem cell-like subpopulation, and human CRC specimens.
Initially the size of the CD133-expressing (CD133+) population in eight well-described CRC cell lines was measured by flow cytometry and was found to range from 0% to >95%.
We assessed CD133 mRNA expression levels by RT-QPCR in tumour and matched normal tissue from 64 stages I-III colorectal cancer (CRC) patients and correlated tumour CD133 levels with clinicopathological characteristics and clinical outcome.
Elevated CD133 mRNA levels may represent more aggressive tumor biology and poorer survival in patients with colorectal cancer, correlating with a high level of MSI status.
By Cox progression analysis, it was shown that CEA/CK/CD133 mRNA in tumor drainage blood was an independent prognostic factor for DFS and OS in patients with Dukes' stage B and C. These results suggest that detecting CEA/CK/CD133 mRNA in tumor drainage blood by the real-time RT-PCR method would have a prognostic value in CRC patients with Dukes' stage B and C.
Expression levels of CD133, a cancer stem cell marker, and of the α-subunit of the dystroglycan (α-DG) complex, have been previously reported to be altered in colorectal cancers.
After Cox regression, age, Duck's stage, lymph node metastasis, and CD133 and CD44 proteins co-expression were shown to be the independent prognostic factors of colorectal cancers.
Therefore, definite conclusions can not be drawn yet, but it is strongly suggestive that CD133 should not be used as a single CSC marker of colorectal cancer.
CD133-positive CTC may represent a suitable prognostic marker to stratify the risk of patients who undergo liver resection for CRC metastasis, which opens the avenue to identifying and potentially monitoring the patients who are most likely to benefit from adjuvant treatments.
In light of the recent discovery of tumor-initiating cancer stem cells (CSCs) in various tumor types, we developed an in vitro CSC model from xenograft tumors established in mice from a colorectal cancer patient tumor in which the CD133+/EpCAM+ population represented tumor-initiating cells.