Riluzole Induces Apoptotic Cell Death in Human Prostate Cancer Cells via Endoplasmic Reticulum Stress

Background: Ion channel modulators have been previously associated with cell proliferation and cell death in human cancer cell lines. Materials and Methods: The effects of riluzole, an ion channel modulator, on cell proliferation, apoptosis and the apoptotic pathway in the LNCaP and C4-2 prostate cancer cell lines were investigated. Results: Riluzole inhibited DNA synthesis and increased apoptotic cells in both cell lines. The activities of caspase-3, -8 and -9 were significantly increased, and caspase inhibitors for caspase-3, -8 and -9 significantly rescued the cell viability of both carcinoma cell lines treated with riluzole. However, a change in mitochondrial membrane potential, release of cytochrome c and cleavage of Bid were not observed in the riluzole-treated cells. Riluzole significantly induced elevation of caspase-4 activity, fluorescence indicating cytosolic calcium, and morphological changes in endoplasmic reticulum (ER) as observed by transmission electron microscopy. Conclusion: Riluzole induces inhibition of DNA synthesis and apoptotic cell death via ER stress in both the LNCaP and C4-2 prostate cancer cell lines.