| Summary: | 碩士 === 國立臺灣大學 === 病理學研究所 === 102 === Nasopharyngeal carcinoma (NPC) is one of the leading cause of cancer-related deaths in southeastern China and South East Asia. However, the detailed pathogenetic mechanisms of NPC remain to be elucidated. Despite novel therapies and advances in early detection, it is often diagnosed at an advanced stage and has a poor prognosis. Recent evidences showed that SRY (sex-determining region Y)-box 5 (SOX5) plays an important role in nasopharyngeal cancer progression, but little is known about the role of its associated protein such as VNN3 gene (vascular non-inflammatory molecular 3) in controlling tumor progression. Previously, our laboratory had found that SOX5 overexpression enhances tumor progression in NPC, and has a poor prognosis. In this study, we compared the differential gene expression in SOX5 over-expressed and regular expressed NPC cell lines by cDNA microarray analysis, and observed that the RNA and protein expression levels of SOX5 were dramatically increased in the SOX5 gene over-expressed NPC cells by qRT-PCR and Western blot analysis. At the same time we also found that VNN3 was significantly increased in NPC cell lines. In order to investigate that whether VNN3 gene could also alter NPC progression, we observed at first the gene expression in different NPC cell lines using qRT-PCR analysis and found that the expression of VNN3 in NPC cell line, especially in NPC-TW01 cell line was highly upregulated. Besides, we also revealed that the expression level of VNN3 protein was increased in multiple NPC cell lines and NPC biopsy specimens by immunohistochemical staining and Western bloting. In this study, we have established the NPC cancer stem cells (CSCs) from NPC-TW01 cell line by conditioned culture medium; highly expression level of VNN3 gene was found in the NPC-TW01 cancer stem cells (NPC-CSCs). To further analysis of the functional role of VNN3 in this NPC-CSCs line, the expression of VNN3 was decreased to about 95% of the control in NPC CSCs after knockdown of VNN3 by VNN3 shRNA-lentiviral infection. This in turn resulted in a significant reduction of cell proliferation, migration and invasion abilities. VNN3 is an amidohydrolase that hydrolyzes pantetheine into pantothenic acid (vitamin B5) as well as cysteamine, both them are free radical scavenger when VNN3 expression was suppressed, it caused an increase of intracellular reactive oxygen species (ROS), and cell death through apoptosis; beside the weight of NPC xenograft tumors from these lentiviral infected NPC CSCs cell lines had diminished about 51% after 6 weeks, compared with shLuc control in SCID mice. Impairment of tumor cell proliferation, accompanied with necrosis and apoptosis was also found in the NPC-CSC xenografts treated with VNN3 shRNA histopathologically. These novel findings of the functional role of VNN3 may have a potential implication in molecular targeted therapy for NPC.
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