The bioactive sphingolipid metabolite sphingosine 1-phosphate (S1P), recently was reported to induce apoptosis of some cancer cells and neurons, although it generally known to exert mitogenic and antiapoptotic effects. In this study, we investigated the effects of S1P on the cell growth, melanogenesis, and apoptosis of cultured B16 mouse melanoma cells. In results, S1P was found to induce apoptosis in B16 melanoma cells in a dose- and time-dependent manner, but exerted minimal effects on melanogenesis. Although receptors of sphingosine 1-phosphate (endothelial differentiation gene 1 [Edg]/S1P1, Edg5/S1P2, Edg3/S1P3) were expressed in B16 melanoma cells, they were shown not to be associated with S1P-induced apoptosis. In addition, pertussis toxin did not block the apoptotic effects of S1P on B16 melanoma cells. S1P induced caspase-3 activation and the extracellular signal-regulated kinase (ERK) activation. Interestingly, the ERK pathway inhibitor, UO126, reversed the apoptotic effects of S1P on B16 melanoma cells. These results suggest that S1P induced apoptosis of B16 melanoma cells via an Edg receptor-independent, pertussis toxin-insensitive pathway, and appears to be associated with the ERK and caspase-3 activation.
Sphingosine/administration & dosage/*analogs & derivatives ; Signal Transduction/drug effects ; Mice ; Melanoma/*enzymology/*pathology ; Lysophospholipids/*administration & dosage ; Extracellular Signal-Regulated MAP Kinases/*metabolism ; Enzyme Activation/drug effects ; Cell Line ; Caspase 3/*metabolism ; Apoptosis/*drug effects ; Animals

OBJECTIVETo investigate the effects of sphingosine-1-phosphate (S1P) on cyclophosphamid (CTX) and cisplatin (DDP)-induced ovarian damage and on the efficacy of chemotherapy in mice bearing S180 murine sarcoma.

METHODSFifty-two female C57BL/6 mice were randomized into normal control group (n=10), tumor-bearing model group (n=14), CTX+DDP group (n=14), and S1P+CTX+DDP group (n=14). Before medication and on day 11 of medication during diestrus stage, the mice were sacrificed to measure the ovarian weight, numbers of primordial follicles and growing follicles, tumor weight, and serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol ( E2).

RESULTSAt day 11 of medication, the levels of serum FSH and E2, but not LH, showed significant differences in CTX+DDP group from those in the other groups (P<0.01). FSH, E2, and LH levels were comparable between S1P+CTX+DDP group and the control group (P>0.05). The number of primodial follicles and weight of ovaries in CTX+DDP group decreased significantly compared to those in the other groups (P<0.01). The number of growing follicles in CTX+DDP group was significantly lower than that in the control and model groups(P<0.01), but similar to that in S1P group (P>0.05). The number of primodial follicles and growing follicles and ovarian weight in S1P+CTX+DDP group were close to those in the control and model groups (P>0.05). In CTX+DDP and S1P+CTX+DDP groups, the tumor weight were significantly lower than that in the other two groups (P<0.01), and the tumor inhibition rates were both higher than 60%.

CONCLUSIONS1P can ameliorate chemotherapy-induced ovarian damage in mice without affecting the efficacy of chemotherapy.

Animals ; Antineoplastic Combined Chemotherapy Protocols ; adverse effects ; therapeutic use ; Cisplatin ; administration & dosage ; adverse effects ; Cyclophosphamide ; administration & dosage ; adverse effects ; Female ; Lysophospholipids ; therapeutic use ; Mice ; Mice, Inbred C57BL ; Primary Ovarian Insufficiency ; chemically induced ; prevention & control ; Sarcoma 180 ; drug therapy ; Sphingosine ; analogs & derivatives ; therapeutic use