S1P5 is required for sphingosine 1-phosphate-induced autophagy in human prostate cancer PC-3 cells
Journal
American Journal of Physiology - Cell Physiology
Journal Volume
297
Journal Issue
2
Pages
C451-C458
Date Issued
2009
Author(s)
Abstract
Sphingosine 1-phosphate (S1P) is a platelet- and endothelial cell-released lysophospholipid that regulates various cellular functions through activating a specific family of G protein-coupled receptors. Both platelet activation and angiogenesis play important roles in cancer development, implying that cancer cells might encounter a large amount of S1P during these processes. Cancer cells, in the meantime, may experience nutrient deprivation and rely on autophagy for early development. Whether extracellular S1P regulates autophagy remains to be tested. In the present work, we investigated whether autophagy is regulated by S1P in PC-3 cells. Through monitoring the modification patterns of LC3 by Western blotting, we demonstrated that autophagy was induced by exogenously applied S1P in PC-3 cells. This observation was further confirmed by fluorescence microscopy using PC-3 cells stably expressing enhanced green fluorescent protein-LC3. By applying small interfering RNA and dihydro-S1P, S1P5 activation was found to be involved in this process. Besides, mammalian target of rapamycin signaling was inhibited upon S1P treatment. Taken together, our results suggest that, under serum-starved conditions, S1P further upregulates autophagic activity through S1P5-dependent pathways in PC-3 cells. Copyright ? 2009 the American Physiological Society.
SDGs
Other Subjects
green fluorescent protein; mammalian target of rapamycin; small interfering RNA; sphingosine 1 phosphate; angiogenesis; article; autophagy; cancer cell; cancer cell culture; carcinogenesis; cell function; cell strain PC 3; controlled study; endothelium cell; fluorescence microscopy; human; human cell; male; monitoring; nonhuman; nutrient; priority journal; prostate cancer; protein function; thrombocyte activation; Western blotting; Animals; Autophagy; Cell Line, Tumor; Humans; Lysophospholipids; Male; Microtubule-Associated Proteins; Phagosomes; Prostatic Neoplasms; Protein Kinases; Receptors, Lysosphingolipid; Recombinant Fusion Proteins; Ribosomal Protein S6 Kinases, 70-kDa; RNA, Small Interfering; Signal Transduction; Sphingosine; Mammalia
Type
journal article