Evaluation of Serum Tumor Endothelial Marker 1 as a Potential Biomarker for Colorectal Cancer Diagnosis and Cancer Progression

Colorectal cancer (CRC) is a serious health problem, a challenge for research, and a model for studying the molecular mechanisms involved in its development. Colorectal cancer is the third most common cancer in the world with approximately 1.4 million new cases and almost 700,000 associated deaths reported per year. The incidence, morbidity, and mortality rates of CRC are expected to increase due to population aging and profound adverse effects of many life style-related factors.

Tumor growth is dependent on the complex and multistage angiogenesis. Tumor blood vessels are characterized with abnormal morphology and function compared to normal blood vessels. Except for disorganized structure, abnormal basement membrane, and increased leakiness, tumor vascular cells express unique protein named (Tumor endothelial marker 1 (TEM1)- endothialin-CD248) .

Tumor endothelial marker is a transmembrane glycoprotein which expression is significantly higher in tumor vasculature (5-,10-, and 20-fold) compared to the vessels of healthy tissues. It was suggested TEMs could discriminate between tumor and nontumor vascular cells.

Tissue overexpression of TEM1 was found in patients with CRC compared to healthy controls as well as in rectal cancer tissues when comparing tumor, lymph nodes, metastasis (TNM) stage I with other stages: TNM II, III, IV , Although the biology of TEM1 is intensely studied, including clinical studies with anti-TEM1 molecules, Only one study (2020) determined the potential usefulness of serum TEM1 in CRC. Pietrzyk (2020) revealed that TEM1 demonstrated higher levels in the serum of the patients with CRC than healthy individuals and reported that TEM1 could act as a potential diagnostic, progression, and prognostic serum biomarker for patients with CRC. Most commonly used serum markers for diagnosis and monitoring of CRC are carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (Ca 19-9). However, these markers show insufficient sensitivity, especially at early stages of CRC. Therefore, finding sensitive and specific, noninvasive, serum biomarkers is a prerequisite for early CRC diagnosis.