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論文 |
論文
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Li, You Qiang ; Mizokami, Atsushi ; Izumi, Kouji ; Narimoto, Kazutaka ; Shima, Takashi ; Zhang, Jian ; Dai, Jinlu ; Keller, Evan T. ; Namiki, Mikio
概要:
金沢大学附属病院泌尿器科<br />BACKGROUND. Recently, we established paclitaxel-resistant prostate cancer cell lines (PC-3-TxR and DU1
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45-TxR). To determine the mechanisms of paclitaxel resistance in PC-3-TxR cells, we compared the gene expression profiles between PC-3 and PC-3-TxR cells. Our results indicated that expression of the C-terminal tensin like protein (CTEN, tensin 4) gene was down-regulated by 10-fold in PC-3-TxR cells. We investigated the possibility that CTEN overexpression restores paclitaxel sensitivity. METHODS. We investigated how knockdown and overexpression of CTEN in androgen-independent cell lines affect paclitaxel sensitivity by colony formation assay and growth inhibition assay. To determine the mechanisms by which CTEN affects paclitaxel sensitivity, we investigated the relationships between CTEN and F-actin or epidermal growth factor receptor (EGFR) in PC-3 cells. We also examined the association between expression of CTEN and grade of prostate cancer by immunohistochemistry using tissue microarray analysis. RESULTS. Down-regulation of CTEN, which is located in the cytoskeleton, played an important role in paclitaxel resistance in PC-3-TxR cells. Knockdown of CTEN expression in PC-3 cells induced paclitaxel resistance. Overexpression of CTEN in PC-3-TxR and DU145-TxR cells restored paclitaxel sensitivity. CTEN expression was inversely correlated with F-actin and EGFR expression. Then knockdown of actin and EGFR in PC-3-TxR cells recovered paclitaxel sensitivity, indicating that CTEN down-regulation mediates paclitaxel resistance through elevation of EGFR and actin expression. Moreover, CTEN expression was inversely correlated with Gleason score. CONCLUSIONS. These results strongly suggested that CTEN plays an important role in paclitaxel sensitivity and that CTEN expression level may be a prognostic predictive factor for PCa patients. © 2009 Wiley-Liss, Inc.
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論文 |
論文
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Mizokami, Atsushi ; Koh, Eitetsu ; Izumi, Kouji ; Narimoto, Kazutaka ; Takeda, Masashi ; Honma, Seijiro ; Dai, Jinlu ; Keller, Evan T. ; Namiki, Mikio
概要:
金沢大学附属病院泌尿器科<br />One of the mechanisms through which advanced prostate cancer (PCa) usually relapses after androgen dep
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rivation therapy (ADT) is the adaptation to residual androgens in PCa tissue. It has been observed that androgen biosynthesis in PCa tissue plays an important role in this adaptation. In the present study, we investigated how stromal cells affect adrenal androgen dehydroepiandrosterone (DHEA) metabolism in androgen-sensitive PCa LNCaP cells. DHEA alone had little effect on prostate-specific antigen (PSA) promoter activity and the proliferation of LNCaP cells. However, the addition of prostate stromal cells or PCa-derived stromal cells (PCaSC) increased DHEA-induced PSA promoter activity via androgen receptor activation in the LNCaP cells. Moreover, PCaSC stimulated the proliferation of LNCaP cells under physiological concentrations of DHEA. Biosynthesis of testosterone or dihydrotestosterone from DHEA in stromal cells and LNCaP cells was involved in this stimulation of LNCaP cell proliferation. Androgen biosynthesis from DHEA depended upon the activity of various steroidogenic enzymes present in stromal cells. Finally, the dual 5a-reductase inhibitor dutasteride appears to function not only as a 5a-reductase inhibitor but also as a 3b-hydroxysteroid dehydrogenase inhibitor in LNCaP cells. Taken together, this coculture assay system provides new insights of coordinate androgen biosynthesis under the microenvironment of PCa cells before and after ADT, and offers a model system for the identification of important steroidogenic enzymes involved in PCa progression and for the development of the corresponding inhibitors of androgen biosynthesis. © 2009 Society for Endocrinology.
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