S1P(5) is required for sphingosine 1-phosphate-induced autophagy in human prostate cancer PC-3 cells.
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, S1P(5) 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 S1P(5)-dependent pathways in PC-3 cells.
Chang
Chi-Lun
CL
Institute of Zoology, National Taiwan University, Taipei, Taiwan, ROC.
Ho
Ming-Chih
MC
Lee
Po-Huang
PH
Hsu
Chi-Yen
CY
Huang
Wei-Pang
WP
Lee
Hsinyu
H
D000818:Animals; D001343:Autophagy / Q000502:physiology*; D045744:Cell Line, Tumor; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism*; D008297:Male; D008869:Microtubule-Associated Proteins; D010588:Phagosomes / Q000378:metabolism; D011471:Prostatic Neoplasms; D011494:Protein Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases
D008246:Lysophospholipids; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D011993:Recombinant Fusion Proteins; C060506:sphingosine 1-phosphate; D011494:Protein Kinases; C546842:MTOR protein, human; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D013110:Sphingosine