Chapter 2 Urinary Markers in Colorectal Cancer

Clinical and biological significance of circulating tumor cells, circulating tumor DNA, and exosomes as biomarkers in colorectal cancer

Colorectal cancer (CRC) has been the fourth leading cause of cancer-related mortality worldwide. Owing to clonal evolution and selection, CRC treatment needs multimodal therapeutic approaches and due monitoring of tumor progression and therapeutic efficacy. Liquid biopsy, involving the use of circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and exosomes, may offer a promising noninvasive alternative for diagnosis and for real-time monitoring of tumor evolution and therapeutic response compared to traditional tissue biopsy. Monitoring of the disease processes can enable clinicians to readily adopt a strategy based on optimal therapeutic decision-making. This article provides an overview of the significant advances and the current clinical and biological significance of CTCs, ctDNA, and exosomes in CRC, as well as a comparison of the main merits and demerits of these three components. The hurdles that need to be resolved and potential directions to be followed with respect to liquid biopsies for detection and therapy of CRC are also discussed.

Surface plasmon resonance biosensor for parallelized detection of protein biomarkers in diluted blood plasma

Surface plasmon resonance (SPR) biosensor for high-throughput screening of protein biomarkers in diluted blood plasma is reported. The biosensor combines a high-resolution SPR imaging sensor and a high-density protein array with low-fouling background. The SPR imaging sensor utilizes polarization contrast and advanced referencing and provides a total of 120 sensing areas (each 200 μm×150 μm). Antibodies are immobilized on the sensing areas via hybridization of antibody-oligonucleotide conjugates to thiolated complementary oligonucleotides microspotted on the sensor surface (DNA-directed immobilization). A low-fouling background is achieved by covalent immobilization of bovine serum albumin to carboxyl-terminated thiols filling the areas among the thiolated oligonucleotides and outside the sensing areas. The biosensor was evaluated for detection of protein biomarkers relevant to cancer diagnostics--human chorionic gonadotropin (hCG) and activated leukocyte cell adhesion molecule (ALCAM) both in buffer and in 10% blood plasma. Limits of detection as low as 45 ng/mL (ALCAM) and 100 ng/mL (hCG) were achieved in blood plasma samples.

Molecular detection of colorectal neoplasia

A variety of noninvasive molecular approaches to colorectal cancer screening are emerging with potential to improve screening effectiveness and user-friendliness. These approaches are based on the sensitive assay of molecular markers in stool, blood, and urine samples. New methods, especially next generation stool-based tests, have been shown to detect both colorectal cancers and precancerous lesions with high accuracy. Validation of these technologies in average-risk populations are needed to establish their role for general colorectal cancer screening. This review addresses the biological rationale, technical advances, recent clinical performance data, and remaining issues with molecular screening for colorectal cancer.

Monoclonal antibodies MC3 and MC5 can be used as a tool for screening colorectal cancer

MC3 and MC5 are both colorectal cancer-specific MAbs previously prepared in our laboratory that can detect colorectal cancer with high sensitivity and specificity. Thus far the distribution of MC3-Ag and MC5-Ag in colorectal cancer remains largely unknown. In the present study, we have firstly found that the expression of MC3-Ag and MC5-Ag was higher in moderate-differentiated and poor-differentiated colorectal cancer tissue than that in well-differentiated colorectal cancer tissue by immunohistochemistry. The expression of MC5-Ag in colorectal cancer tissue without metastasis was found to be significantly less than that in tissue accompanied with metastasis. However, the expression of MC3-Ag in colorectal cancer tissue without metastasis was found similar to that in tissue accompanied with metastasis. The results showed that MC3-Ag and MC5-Ag might play important roles in colorectal carcinogenesis and that MC3 and MC5 could be used as a tool for screening colorectal cancer.