| Summary: | 博士 === 長庚大學 === 臨床醫學研究所 === 99 === Notch signaling is known to play a critical role in cell proliferation, differentiation, and survival. It is also involved in control of tumorigenesis and in the self-renewal of stem cells. We set out to examine the clinical significance of expression of Jagged-1 and Notch-1 in 59 patients with head and neck cancers. We found that high-level coexpression of Jagged-1 and Notch-1 is associated with poor overall survival in patients with head and neck cancer. Constitutive activation of the Notch signaling confers tumor cells with a more aggressive phenotype. As the CD44 marker of cancer stem cells was found to have stem cell-like properties of self-renewal and pluripotency in human head and neck carcinoma, we examine the relationship between Notch1 and CD44 expression. In addition, we also found that Notch1 expression up- regulates the CD44 expression in head and neck tumor cells. We therefore investigate the clinical significance of CD44 messenger RNA (mRNA) expression in the peripheral blood of 54 patients with head and neck cancer. We showed that the pretreatment CD44 mRNA levels at a cutoff point of greater than fivefold by real-time reverse transcriptase- polymerase chain reaction analysis were associated with poor prognosis and could predict poor treatment response in patients with locally advanced head and neck cancers. Taken together, Notch1 is important in the tumorigenesis of head and neck cancer. Furthermore, the association of Notch1 with CD44 stem cell marker might be important in the malignant phenotype in head and neck cancer.
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