Guanylyl Cyclase C as a tumor marker for detection of circulating tumor cells in the peripheral blood of colorectal cancer patients

Purpose: Guanylyl cyclase C (GCC) is one of the most frequent tumor markers to detect the circulating tumor cells (CTCs) in peripheral blood of colorectal cancer (CRC) patients. It has been proposed as a new marker for the molecular staging of CRC. The level of GCC mRNA expression in peripheral blood of CRC patients was evaluated to explore its probable correlations with the clinicopathological features.Methods: Relative quantitative expression analysis of GCC mRNA was performed on 80 blood samples (40 patients and 40 normal) using the Real-time RT-PCR.Results: GCC mRNA expression was detected in 70% of the CRC blood samples. The level of GCC mRNA expression in peripheral blood of patients was significantly higher than that in the normal cases (p = 0.031). Moreover, there was a significant correlation between the GCC copy number and advanced stages of tumor (p = 0.041). Furthermore, we have observed a significant correlation between tumor sizes and GCC copy numbers (p = 0.050).Conclusion: GCC can be a useful marker not only for detection of CTCs in CRC blood samples, but also for the molecular staging of colorectal cancer.