The Expression of DCC Protein in Colorectal Carcinomas

ABSTRACT

Colorectal cancer is one of the malignant tumours of which molecular genetic alterations have been much unveiled among the human cancers. In the multi-stepwise process to the carcinogenesis, it has been recently revealed that the neoplastic growth is originated either from the activiation of oncogene through its mutation, rearragement and amplification, or from the inactivation of the tumour suppression gene through its mutation and deletion. DCC(Deleted in colon cancer) protein is the product of DCC gene, the representative of tumor suppressor genes. The alteration of DCC protein may be related with the aggressiveness of carcinoma and metastasis. As a result, the prognosis of the cancer may be also thought to be affected. Now the prognosis of colorectal cancer mainly depends on pathologic staging, but there are some variations of survival and recurrence among the patients in same stage. Then this study is aimed to reveal the significance of alteration of DCC protein as an independent factor related to prognosis. Twenty three cancer tissues were obtained from the rejected specimens of colorectal carcinomas. We exacted the DCC gene products in the cancer tissues by the methods of immunohistochemical stains and Western blots. We also analyzed the relationships between the alteration of DCC proteins and the status of regional lymph node metastasis or the serum levels of CEA's(carcinoembryonic antigen). As results, we found the abscence or very scanty stains of DCC protein by Western lot in 14 cancer tissues of available 19 cases, but there were all negative responses in immunohistochemical stains. In contrast with above results, there were all positively stains of DCC proteins in corresponding 23 normal colorectal tissues by both the methods. There was no significantly statistical relation between the alteration of DCC proteins and the status of regional lymph node metastasis or the serum level of CEA. In conclusion, we can confirm that the DCC proteins are abscent or very scanty in colorectal cancer tissues and that may be related with the process of carcinogenesis. But the role of DCC protein loss as an independent prognostic factor was not found in this study.