Down-regulated expression of Tim-3 promotes invasion and metastasis of colorectal cancer cells
Abstract:
To explore how Tim-3 is expressed and how its expression influences invasion and metastasis of colorectal cancer (CRC) cells. A total of 188 CRC patients were prospectively collected for this study. Meanwhile, 135 normal controls were incorporated during the same period. Intestinal samples of the CRC radical cancerous tissues, paracancerous tissues ( 5.0 cm beyond the cancer tissue) were collected for the following experiment. Furthermore, peripheral venous blood samples (10 ml) were collected from each subject. Immunohistochemical analysis, quantitative real-time polymerase chain reaction (RT-qPCR) and western blot were performed for the detection of Tim-3 in different tissues. The immunohistochemical staining results showed that a positive Tim-3 signal was localized in the cytoplasm and nucleus, observed as yellow or brown granules. Tim-3 was largely expressed in colon carcinoma tissues and normal colon mucosa tissues but was rarely expressed in the cell membrane. RT-qPCR results indicated that Tim-3 mRNA levels were significantly lower in CRC tissues than in paracancerous tissues and normal colon mucosa tissues. A trend of decreased Tim-3 mRNA levels was also found in the paracancerous tissues compared with the normal colon mucosa tissues (all P