• Open Access

Down-regulation of cyclooxygenase-2 expression but up-regulation of cyclooxygenase-1 in renal carcinomas of the Eker (TSC2 gene mutant) rat model

Authors

  • Toshihiro Okamoto,

    1. Research Laboratories, Nippon Chemiphar Co., Ltd., Saitama 341–0005
    2. Department of Experimental Pathology, Cancer Institute, Japanese Foundation for Cancer Research, 1–37–1 Kamiikebukuro, Toshimaku, Tokyo 170–0005
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  • Atsuko Hara,

    1. Research Laboratories, Nippon Chemiphar Co., Ltd., Saitama 341–0005
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  • Okio Hino

    Corresponding author
    1. Department of Experimental Pathology, Cancer Institute, Japanese Foundation for Cancer Research, 1–37–1 Kamiikebukuro, Toshimaku, Tokyo 170–0005
      E-mail: ohino@ims.u-tokyo.ac.jp
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    • 3

      To whom correspondence should be addressed.


E-mail: ohino@ims.u-tokyo.ac.jp

Abstract

Although it is generally accepted that cyclooxygenase (Cox)- 2 is overexpressed in carcinomas, few studies have examined Cox-2 expression in renal carcinoma (RC). The Eker rat RC is an example of a Mendelian dominantly inherited carcinoma, and in the present study, expression of Cox-2 in the Eker rat RC was examined. Reverse transcription polymerase chain reaction indicated constitutive expression of Cox-2 mRNA in the normal control kidney and non-tumor part of Eker rat kidney. Unexpectedly, expression of Cox-2 mRNA was down-regulated in four Eker RCs from two Eker rats, and in the cell line Lk9ds. Immunohistochemical analysis failed to reveal Cox-2 protein staining in Eker RCs. As a control to Cox-2 expression, Cox-1 expression was examined. Interestingly, in contrast to the down-regulated Cox-2 expression, Cox-1 mRNA expression was induced in these four Eker RCs and cell lines. Cox-2 and Cox-1 expression were further examined in six additional Eker RCs. In total, Cox-2 mRNA expression was down-regulated in eight out of ten Eker RCs and cell lines, while Cox-1 mRNA expression was up-regulated in nine out of ten Eker RCs and cell lines. (Cancer Sci 2003; 94: 22–25)

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