Abstract
To study the expression of angiogenin-2 (Ang-2) and its receptor Tie-2 in colorectal cancer and discuss the possible mechanisms behind this process. Using the streptavidin-peroxidase (SP) immunohistochemical method, paraffin sections from 100 colorectal cancer samples and 10 samples from tumor-adjacent normal tissue (>2 cm from the edge of the gross tumor) were tested for protein expression of Ang-2, Tie-2, PI3K, and AKT. Reverse transcription-polymerase chain reaction and Western blots were further used to measure expression of the 4 genes and proteins in 20 freshly-resected colorectal cancer samples and tumor-adjacent normal tissues. In colorectal cancer tissues, the expression of the Ang-2, Tie-2, PI3K, and AKT genes and their proteins was significantly higher than in tumor-adjacent normal tissues. Protein expression in poorly-differentiated adenocarcinoma was higher than that in well and moderately differentiated adenocarcinoma. According to Duke's classification, the protein expression in Stages C and D was significantly higher than that in Stages A and B. In the group with lymphatic metastasis, the protein expression was higher than that without lymphatic metastasis. In colorectal cancer, the expression of the Ang-2, Tie-2, PI3K, and AKT genes and their proteins is markedly higher than those in tumor-adjacent normal tissues. No correlation was observed between protein expression and gender, location, or histologic type. Correlations did exist between protein expression and differentiation level, stage of Duke's classification, and lymphatic metastasis; in colorectal cancer tissues with lower differentiation levels, higher stages of Duke's classification, and lymphatic metastasis, the expression of all 4 proteins was higher. The study of their expression patterns and relationships with aggression and metastasis will provide a valuable experimental foundation for assessing prognosis and targeted therapy of colorectal cancer.
Highlights
Colorectal cancer is one of the most common malignant tumors threatening human health
Tie-2 was expressed in the cytoplasm of glandular in colorectal cancer tissues was higher than that in tumorepithelial cells, and 2 of 10 samples of tumor-adjacent adjacent tissues (p
The positive expression rate of Tie-2 the positive expression rate of Ang-2 in papillary in colorectal cancer tissue was significantly higher than adenocarcinoma, tubular adenocarcinoma and other that in tumor-adjacent tissue (p
Summary
Colorectal cancer is one of the most common malignant tumors threatening human health. Researchers in China and other countries have confirmed that Ang-2 and its receptor Tie-2 are highly expressed in Lung cancer, ovarian cancer, cervical cancer and colorectal cancer Little data on the relationship between Ang-2/Tie-2 and colorectal cancer exists. Recent studies have demonstrated that many human tumors, for example ovarian cancer, pancreatic cancer, breast cancer, and non-small cell lung cancer, overexpressed PI3K/AKT (Kang et al, 2010; Cheng et al, 2011). Few reports concerning the relationship between PI3K/AKT and colorectal cancer have been published. Taking tumor-adjacent tissue as the control, the gene levels of Ang-2, Tie-2, PI3K, and AKT and their protein expressions in colorectal cancer tissue were measured in order to reveal their correlation with clinical pathological characteristics. This study intended to elucidate the possible mechanism behind the occurrence of colorectal cancer
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