Evaluation of bioactive sphingolipids in 4-HPR-resistant leukemia cells

Background -- N-(4-hydroxyphenyl)retinamide (4-HPR, fenretinide) is a synthetic retinoid with potent pro-apoptotic activity against several types of cancer, but little is known regarding mechanisms leading to chemoresistance. Ceramide and, more recently, other sphingolipid species (e.g., dihydroceramide and dihydrosphingosine) have been implicated in 4-HPR-mediated tumor cell death. Because sphingolipid metabolism has been reported to be altered in drug-resistant tumor cells, we studied the implication of sphingolipids in acquired resistance to 4-HPR based on an acute lymphoblastic leukemia model. Methods -- CCRF-CEM cell lines resistant to 4-HPR were obtained by gradual selection. Endogenous sphingolipid profiles and in situ enzymatic activities were determined by LC/MS, and resistance to 4-HPR or to alternative treatments was measured using the XTT viability assay and annexin V-FITC/propidium iodide labeling. Results -- No major crossresistance was observed against other antitumoral compounds (i.e. paclitaxel, cisplatin, doxorubicin hydrochloride) or agents (i.e. ultra violet C, hydrogen peroxide) also described as sphingolipid modulators. CCRF-CEM cell lines resistant to 4-HPR exhibited a distinctive endogenous sphingolipid profile that correlated with inhibition of dihydroceramide desaturase. Cells maintained acquired resistance to 4-HPR after the removal of 4-HPR though the sphingolipid profile returned to control levels. On the other hand, combined treatment with sphingosine kinase inhibitors (unnatural (dihydro)sphingosines ((dh)Sph)) and glucosylceramide synthase inhibitor (PPMP) in the presence or absence of 4-HPR increased cellular (dh)Sph (but not ceramide) levels and were highly toxic for both parental and resistant cells. Conclusions -- In the leukemia model, acquired resistance to 4-HPR is selective and persists in the absence of sphingolipid profile alteration. Therapeutically, the data demonstrate that alternative sphingolipid-modulating antitumoral strategies are suitable for both 4-HPR-resistant and sensitive leukemia cells. Thus, whereas sphingolipids may not be critical for maintaining resistance to 4-HPR, manipulation of cytotoxic sphingolipids should be considered a viable approach for overcoming resistance.

Edoskitzea, opioideoen ondoriozko abstinentzia sindrome neonatalaren tratamendu eraginkorra?

[EUS]Helburuak: Berrikuspen bibliografiko honen helburu orokorra edoskitzea opioideekiko abstinentzia sindrome neonatalaren sintomak arintzeko eraginkorra den aztertzea izango da, eta baita honek tratamendu farmakologikoaren beharra gutxitzen duen. Bestalde, metadona hartzen duten emakume hauen esneko metadona kontzentrazioa nolakoa den eta esne honen bitartez jaioberriari heltzen zaion kantitatea nolakoa den identifikatu nahi da. Metodologia: Artikuluen bilaketa egiteko, datu base desberdinak erabili dira, baina erabilitako azken 8 artikuluak Pubmed eta Ovid-sp-ekoak dira. Artikulu guztiak bat izan ezik, ingelesezkoak dira, gaztelaniaz aurkitutako artikulu kantitate eskasa dela eta. “Edoskitzea” , “abstinentzia sindrome neonatala” eta “metadona terapia" terminoak erabili dira bilaketa prozesuan. Ondorioak: Edoskitzea opioideekiko abstinentzia sindrome neonatala jasaten duten jaioberrientzat gomendagarria dela esan daiteke, ikerketa hauen arabera, abstinentziaren sintomak eta tratamendu farmakologikoaren beharra gutxitzen baititu. Gainera, esneko metadona kontzentrazioa eta jaioberriari honen bitartez heltzen zaion kantitatea oso txikiak dira. Hala ere, lanak limitazioa garrantzitsu bat du, ikerketetako laginak txikiak izatea.