51. The PPARgamma ligand, 15-Deoxy-Delta12,14-PGJ2, regulates apoptosis-related protein expression in cholangio cell carcinoma cells.
- Author
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Okano H, Shiraki K, Inoue H, Kawakita T, Deguchi M, Sugimoto K, Sakai T, Murata K, Nakano T, and Enjoji M
- Subjects
- Humans, Apoptosis drug effects, Cholangiocarcinoma drug therapy, Immunologic Factors pharmacology, Prostaglandin D2 analogs & derivatives, Prostaglandin D2 pharmacology, Protein Biosynthesis
- Abstract
PPARgamma is known to induce apoptosis in malignant tumor cells, but the mechanism of this induction is not well understood. We investigated induction of apoptosis with 15-Deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), a PPARgamma ligand, in cholangio cell carcinoma (CCC) cells (RBE, ETK-1 or HuCCT-1). Apoptosis was induced in RBE and ETK-1 cells with 15d-PGJ2, but not in HuCCT-1 cells, although PPARgamma was expressed in all CCC cells. Apoptosis-related proteins were also expressed, including FLIP, bclx, Apaf-1 and XIAP, but expression levels differed among the three cell lines. RBE cells treated with 15d-PGJ2 showed caspase activation, and it appeared that PPARgamma-induced apoptosis was dependent on caspase activation. However, neither ETK-1 nor HuCCT-1 cells showed significant activation of caspase-8 or -3 with 15d-PGJ2 treatment, raising the possibility of a caspase-independent apoptosis induction pathway. XIAP was down-regulated by 15d-PGJ2 in all three CCC cell lines. Therefore, 15d-PGJ2 induces apoptosis in CCC cells via caspase-dependent or independent pathways. 15d-PGJ2 may also induce down-regulation of XIAP and may promote caspase cascade activation through TNF-family receptor signaling pathways.
- Published
- 2003