First evidence of sphingosine 1-phosphate lyase protein expression and activity downregulation in human neoplasm: implication for resistance to therapeutics in prostate cancer.
This is the first report of sphingosine 1-phosphate lyase (SPL) protein expression and enzymatic activity in human neoplasm. This enzyme drives irreversible degradation of sphingosine 1-phosphate (S1P), a bioactive lipid associated with resistance to therapeutics in various cancers, including prostate adenocarcinoma. In fresh human prostatectomy specimens, a remarkable decrease in SPL enzymatic activity was found in tumor samples, as compared with normal adjacent tissues. A significant relationship between loss of SPL expression and higher Gleason score was confirmed in tissue microarray (TMA) analysis. Moreover, SPL protein expression and activity were inversely correlated with those of sphingosine kinase-1 (SphK1), the enzyme producing S1P. SPL and SphK1 expressions were independently predictive of aggressive cancer on TMA, supporting the relevance of S1P in prostate cancer. In human C4-2B and PC-3 cell lines, silencing SPL enhanced survival after irradiation or chemotherapy by decreasing expression of proteins involved in sensing and repairing DNA damage or apoptosis, respectively. In contrast, enforced expression of SPL sensitized cancer cells to irradiation or docetaxel by tilting the ceramide/S1P balance toward cell death. Interestingly, the S1P degradation products failed to sensitize to chemo- and radiotherapy, supporting the crucial role of ceramide/S1P balance in cancer. Of note, the combination of SPL enforced expression with a SphK1 silencing strategy by further decreasing S1P content made prostate cancer cells even more sensitive to anticancer therapies, suggesting that a dual strategy aimed at stimulating SPL, and inhibiting SphK1 could represent a future approach to sensitize cancer cells to cancer treatments.
CNRS, Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, UPS, IPBS Toulouse Cedex 4, France.
Leyre
L
Brizuela
Isabelle
I
Ader
Catherine
C
Mazerolles
Magalie
M
Bocquet
Bernard
B
Malavaud
Olivier
O
Cuvillier
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000446:Aldehyde-Lyases / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D000077143:Docetaxel; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D008297:Male; D060787:Neoplasm Grading; D011467:Prostate / Q000201:enzymology; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000628:therapy; D034622:RNA Interference; D011836:Radiation Tolerance; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D043823:Taxoids / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; D008246:Lysophospholipids; C466999:SPHKAP protein, human; D043823:Taxoids; D000077143:Docetaxel; C060506:sphingosine 1-phosphate; D020169:Caspases; D000446:Aldehyde-Lyases; C022649:sphingosine 1-phosphate lyase (aldolase); D013110:Sphingosine