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Activation of a nuclear receptor impairs cycloocygenase-2expression but induces apoptosis in human choriocarcinoma cell lines: A possible therapeutic approach for treatment
- Abstract
- Cyclooxygenase-2 (COX-2), the inducible isoform of COX is the enzyme that catalyzes the rate-limiting step in prostaglandin synthesis from arachidonic acid. Various prostaglandins are produced in a cell type-specific manner, and they elicit cellular functions via signaling through G-protein-coupled membrane receptors, and in some cases, through the nuclear receptor peroxisome proliferator-activated receptor (PPAR) e.g. PPARgamma. In a number of cell and animal models, induction of COX-2 has been shown to promote cell growth, inhibit apoptosis and enhance cell motility and adhesion. Compelling eidence from genetic and clinical studies indicate that COX-2 upregulation is a key step in carcinogenesis. Overexpression of COX-2 is sufficient to cause tumorigenesis in animal models and inhibition of the COX-2 pathway results in reduction in tumor incidence and progression, but increased apoptosis (programmed cell death), in parallel. Recent findings revealed that PPARgamma-agonists induce apoptosis in cancer cells via down-regulation of COX-2. PPARgamma binds to specific response elements as heterodimers with the retinoid X receptor and activates transcription in response to a variety of endogenous and exogenous ligands. PPARgamma is needed for plasental development and modulates differentiation of human trophoblast. As the trophoblast may also give rise to choriocarcinomas -malignant tumors of epithelial origin- the present application is aimed to focus on PPARgamma-dependent activities mediating expression and regulation of COX-2 and subsequent induction of apoptotic pathways in choriocarcinoma celll lines in vitro. In this scenario, COX-2 inhibition could afford its effects against choriocarcinoma by modulating COX-2 expression and activity. An exciting corollary to this ongoing pathway is that the parallel increase in apoptotic events via PPARgamma-dependent modulation of COX-2 may exhibit chemoprotective and even chemotherapeutive effects against choriocarcinoma in humans.
- Project Leader:
- Hammer Astrid
- Duration:
- 01.10.2004-01.10.2006
- Type of Research
- basic research
- MUG Research Units
- Division of Cell Biology, Histology and Embryology