Notch1 expression in colorectal carcinoma determines tumor differentiation status.

<bold>Introduction: </bold>The significance of Notch1 expression in colorectal cancer has not been clearly described. We investigated the expression of Notch1 and its relationship with differentiation status and tumor (Union Internationale Contre le Cancer, UICC) stage using a series of 237 colorectal cancer samples with matched adjacent normal tissues and a series of 46 normal colorectal specimens.<bold>Materials and Methods: </bold>Immunohistochemistry, real-time polymerase chain reaction, and Western blot analysis were performed to assess the expression of Notch1.<bold>Results: </bold>It was found that Notch1 was overexpressed in cancer tissues as compared with adjacent normal tissue and normal control tissues. Also, a tendency for increased expression was observed when going from well to poorly differentiated carcinomas, as well as going from UICC stage I to stage IV. With the differentiation of colon cancer cells, the expression of Notch1 decreased. To support this observation, colon cancer cell lines HT29 and SW620 were induced to differentiate in culture, and expression of Notch1 was investigated. A clear reduction of Notch1 expression was observed.<bold>Conclusion: </bold>These results suggest that Notch1 expression correlated closely with colorectal cancer and may play an oncogenic role during colonic carcinogenesis. [ABSTRACT FROM AUTHOR]