Anticancer agents sensitize osteosarcoma cells to TNF–related apoptosis-inducing ligand downmodulating IAP family proteins

Although TNF-related apoptosis-inducing ligand (TRAIL) usually induces cell death in tumor cells, there are some tumor cell types that are resistant to its apoptogenic effects. Some chemotherapeutic drugs, however, can sensitize resistant cancer cells to TRAIL by either upregulating surface TRAIL death receptor expression or by modulating intracellular signalling pathways emanating from TRAIL receptors. U2OS human osteosarcoma cells express TRAIL-R2 but are resistant to TRAIL-induced apoptosis. however, the genotoxic drugs, Doxorubicin and Cisplatin, are able to sensitize U2OS cells to TRAIL, without affecting their surface expression of either death or decoy TRAIL receptors. We demonstrate that Doxorubicin and Cisplatin downmodulate X-IAP, while not affecting FLIP levels in U2OS cells. Selective downmodulation of X-IAP protein synthesis by specific small interference RNA transfection induced a sensitization of U2OS cells to TRAIL comparable to that induced by pharmacological treatment with genotoxic drugs. TRAIL-R2 downmodulation by siRNAs completely abolished the TRAIL-induced apoptosis of genotoxin-treated U2OS cells. Our findings demonstrate that Doxorubicin and Cisplatin do not sensitize U2OS osteosarcoma cells to TRAIL by surface receptor modulation but rather by the removal of the intracellular signalling inhibition generated by X-IAP, suggesting a foreseeable relevant advantage to the therapy of these tumors by the combined regimen of genotoxin-based chemotherapy and TRAIL

Activated human NK and CD8+ T cells express both TNF-related apoptosis-inducing ligand (trail) and trail receptors but are resistant to trail-mediated cytotoxicity

The expression of tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) and TRAIL receptors was investigated in resting and cytokine-activated purified primary human natural killer (NK) and CD8+ T cells. Resting NK and CD8+ T cells expressed the mRNA for all TRAIL receptors, but TRAIL-R4 was the only receptor clearly detectable on the surface of both cell types. NK cells were activated by interleukin 2 (IL-2) or IL-15, whereas CD8+ T cells were activated by phytohemagglutinin (PHA) + IL-2 followed by IL-2 alone for up to 10 days. On activation, both cell types rapidly expressed TRAIL-R2 and TRAIL-R3, whose expression peaked at day 10 of culture. TRAILR1, however, was never expressed at any time point examined, whereas the expression of TRAIL-R4, which showed a progressive increase in CD8+ T cells, remained constant in NK cells. Notwithstanding the expression of TRAIL-R2, recombinant TRAIL did not show any cytotoxic activity on either NK or CD8+ T cells. Both resting and activated NK and CD8+ T cells were found to express high levels of the 2 isoforms of c-FLIP (cellular Fas-associated death domain protein [FADD]–like IL-1–converting enzyme [FLICE]–inhibitory protein). Small interference RNA-mediated inhibition of c-FLIP expression in NK cells abrogated their resistance to the apoptotic effect of soluble TRAIL. Thus, once activated the major cytotoxic effector cells are potentially sensitive to TRAIL but are physiologically protected from its apoptotic action by intracellular level of c-FLIP

Sulfonylurea-responsive neonatal diabetes mellitus diagnosed through molecular genetics in two children and in one adult after a long period of insulin treatment

A permanent neonatal diabetes mellitus has finally been diagnosed through molecular genetics in two children and one adult after 9 to 35 years of uninterrupted insulin treatment. These patients developed diabetes before 6 months of age and were autoantibody negative. In one boy, a mutation in the KCNJ11 gene was identified at 9 years of age. In the other two patients (daughter and father, 12.6 and 25 years old respectively) the new gene variant (ABCC8/L213P) was found. Switching from insulin to sulfonylurea treatment leads to the definitive discontinuance of insulin therapy, improving metabolic control as well as the amelioration of the associated neurodevelopmental disabilities in the young girl in which an intermediate Development Delay, Epilepsy, Neonatal Diabetes syndrome was diagnosed