mRNA expression of apoptosis-associated genes in infant acute lymphoblastic leukemia: low Fas expression is an independent predictor for poor prognosis

The evolution of clinical trials for infant acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) in infants has a significantly inferior outcome in comparison with older children. Despite initial improvements in survival of infants with ALL since establishment of the first pediatric cooperative group ALL trials, the poor outcome has plateaued in recent years. Historically, infants were treated on risk-adapted childhood ALL protocols. These studies were pivotal in identifying the need for infant-specific protocols, delineating prognostic categories and the requirement for a more unified approach between study groups to overcome limitations in accrual because of low incidence. This subsequently led to the development of collaborative infant-specific studies. Landmark outcomes have included the elimination of cranial radiotherapy following the discovery of intrathecal and high-dose systemic therapy as a superior and effective treatment strategy for central nervous system disease prophylaxis, with improved neurodevelopmental outcome. Universal prospective identification of independent adverse prognostic factors, including presence of a mixed lineage leukemia rearrangement and young age, has established the basis for risk stratification within current trials. The infant-specific trials have defined limits to which conventional chemotherapeutic agents can be intensified to optimize the balance between treatment efficacy and toxicity. Despite variations in therapeutic intensity, there has been no recent improvement in survival due to the equilibrium between relapse and toxicity. Ultimately, to improve the outcome for infants with ALL, key areas still to be addressed include identification and adaptation of novel prognostic markers and innovative therapies, establishing the role of hematopoietic stem cell transplantation in first complete remission, treatment strategies for relapsed/refractory disease and monitoring and timely intervention of late effects in survivors. This would be best achieved through a single unified international trial.

Rapid engraftment of human ALL in NOD/SCID mice involves deficient apoptosis signaling

Previously, we found that rapid leukemia engraftment (short time to leukemia, TTL^short) in the NOD/SCID/huALL (non-obese diabetic/severe combined immuno-deficiency/human acute lymphoblastic leukemia) xenograft model is indicative of early patient relapse. As earlier intact apoptosis sensitivity was predictive for good prognosis in patients, we investigated the importance of apoptosis signaling on NOD/SCID/huALL engraftment. Intact apoptosome function as reflected by cytochrome c-related activation of caspase-3 (CRAC-positivity) was strongly associated with prolonged NOD/SCID engraftment (long time to leukemia, TTL^long) of primary leukemia cells, good treatment response and superior patient survival. Conversely, deficient apoptosome function (CRAC-negativity) was associated with rapid engraftment (TTL^short) and early relapse. Moreover, an intact apoptosis signaling was associated with high transcript and protein levels of the pro-apoptotic death-associated protein kinase1 (DAPK1). Our data strongly emphasize the impact of intrinsic apoptosis sensitivity of ALL cells on the engraftment phenotype in the NOD/SCID/huALL model, and most importantly also on patient outcome.

miR-196b directly targets both HOXA9/MEIS1 oncogenes and FAS tumour suppressor in MLL-rearranged leukaemia

HOXA9 and MEIS1 have essential oncogenic roles in mixed lineage leukaemia (MLL)-rearranged leukaemia. Here we show that they are direct targets of miRNA-196b, a microRNA (miRNA) located adjacent to and co-expressed with HOXA9, in MLL-rearranged leukaemic cells. Forced expression of miR-196b significantly delays MLL-fusion-mediated leukemogenesis in primary bone marrow transplantation through suppressing Hoxa9/Meis1 expression. However, ectopic expression of miR-196b results in more aggressive leukaemic phenotypes and causes much faster leukemogenesis in secondary transplantation than MLL fusion alone, likely through the further repression of Fas expression, a proapoptotic gene downregulated in MLL-rearranged leukaemia. Overexpression of FAS significantly inhibits leukemogenesis and reverses miR-196b-mediated phenotypes. Targeting Hoxa9/Meis1 and Fas by miR-196b is probably also important for normal haematopoiesis. Thus, our results uncover a previously unappreciated miRNA-regulation mechanism by which a single miRNA may target both oncogenes and tumour suppressors, simultaneously, or, sequentially, in tumourigenesis and normal development per cell differentiation, indicating that miRNA regulation is much more complex than previously thought.

Regulation of the expression of death receptors and their ligands by melatonin in haematological cancer cell lines and in leukaemia cells from patients

Incorporation of new therapeutic agents remains as a major challenge for treatment of patients with malignant haematological disorders. Melatonin is an indolamine without relevant side effects. It has been shown previously to exhibit synergism with several chemotherapeutic drugs in Ewing sarcoma cells by potentiating the extrinsic pathway of apoptosis. It also sensitizes human glioma cells against TRAIL by increasing DR5 expression. Here, we report the induction of cell death by melatonin in several human malignant haematological cell lines through the activation of the extrinsic pathway of apoptosis. Such activation was mediated by the increase in the expression of the death receptors Fas, DR4 and DR5 and their ligands Fas L and TRAIL, with a remarkable rise in the expression of Fas and Fas L. The cytotoxic effect and the increase in Fas and Fas L were dependent on Akt activation. Results were corroborated in blasts from bone marrow and peripheral blood of acute myeloid leukaemia patients, where melatonin induced cell death and increased both Fas and Fas L expressions. We conclude that melatonin may be considered as a potential antileukaemic agent and its therapeutic use, either alone or in combination with current chemotherapeutic drugs, should be taken into consideration for further research.

Low mRNA expression of the apoptosis-related genes CASP3, CASP8, and FAS is associated with low induction treatment response in childhood acute lymphoblastic leukemia (ALL)

BACKGROUND

Defects in apoptosis signaling have been considered to be responsible for treatment failure in many types of cancer, although with controversial results. The objective of the present study was to assess the expression profile of key apoptosis-related genes in terms of clinical and biological variables and of the survival of children with acute lymphoblastic leukemia (ALL).

PROCEDURE

The levels of mRNA expression of the apoptosis-related genes CASP3, CASP8, CASP9, FAS, and BCL2 were analyzed by quantitative real-time PCR in consecutive samples from 139 consecutive children with ALL at diagnosis treated by the Brazilian protocol (GBTLI-ALL 99). Gene expression levels and clinical and biological features were compared by the Mann-Whitney test. Event-free survival (EFS) was calculated by Kaplan-Meier plots and log-rank test.

RESULTS

A significant correlation was detected between CASP3, CASP8, CASP9, and FAS expression levels (P < 0.01) in ALL samples. Higher levels of BCL2 were significantly associated with white blood cell (WBC) count <50,000/mm(3) at diagnosis (P = 0.01) and low risk group classification (P = 0.008). Lower expression levels of CASP3, CASP8 and FAS gene were associated with a poor response at day 7 according the GBTLI-ALL 99 protocol (P = 0.03, P = 0.02 and P = 0.008, respectively). There was a relationship between FAS gene expression lower than the 75th percentile and lower 5-year EFS (P = 0.02).

CONCLUSION

These findings suggest an association between lower expression levels of the pro-apoptotic genes and a poor response to induction therapy at day 7 and prognosis in childhood ALL.

Prognostic impact of FAS/CD95/APO-1 in urothelial cancers: decreased expression of Fas is associated with disease progression

The death receptor Fas (Apo1/CD95) and Fas ligand (FasL) system is recognised as a major pathway for the induction of apoptosis in vivo, and antiapoptosis via its blockade plays a critical role in carcinogenesis and progression in several malignancies. However, the function of Fas–FasL system in urothelial cancer (UC) has not been elucidated. We therefore investigated the expression of Fas, FasL and Decoy receptor 3 for FasL (DcR3) in UC specimens and cell lines, and examined the cytotoxic effect of an anti-Fas-activating monoclonal antibody (mAb) in vitro. Immunohistochemical examinations of Fas-related molecules were performed on 123 UC and 30 normal urothelium surgical specimens. Normal urothelium showed Fas staining in the cell membrane and cytoplasm. In UC, less frequent Fas expression was significantly associated with a higher pathological grade (P<0.0001), a more advanced stage (P=0.023) and poorer prognosis (P=0.010). Fas and the absence thereof were suggested to be crucial factors with which to select patients requiring more aggressive treatment. Moreover, low-dose anti-Fas-activating mAb sensitised resistant cells to adriamycin, and this synergistic effect could be applied in the development of new treatment strategy for UC patients with multidrug-resistant tumours.

Clinical importance of circulating and cellular expression levels of Fas and Fas ligand in pediatric patients with lymphoproliferative malignancies

Objectives of this study were to determine the extend of soluble Fas (sFas) and soluble FasL (sFasL) at the time of diagnosis and to evaluate its prognostic relevance under chemotherapy in childhood lymphoproliferative malignancies. The authors measured the circulating sFas and sFasL by ELISA in 25 children with newly diagnosed either ALL or NHL, as well as their expression of Fas and FasL at the time of diagnosis and remission. They did not observe any statistically significant difference between the patient group and age-matched healthy controls for sFas levels, whereas sFasL concentration in study population at the time of diagnosis was significantly higher than that in control subjects (1.05 +/- 1.46 vs. 0.36 +/- 0.18 ng/mL, p = .024). At remission the authors observed a significant decrease in the sFasL levels of all patients whose sFasL concentrations were above the minimal detectable level at the time of diagnosis (p = .008). sFasL and Fas/FasL immunohistochemical staining did not have an effect on survival. sFasL may be a marker in monitoring complete remission in children with LPM.