However, blocking the proteolytic activation of NOTCH1 with gamma-secretase inhibitors (GSIs) fails to alter the growth of some T-ALL cell lines carrying the mutated receptor.A recent report by Palomero et al. in Nature Medicine identifies loss of PTEN as a critical event leading to resistance to NOTCH inhibition, which causes the transfer of "oncogene addiction" from the NOTCH1 to the PI3K/AKT pathway.
Along with targeted re-sequencing, our comparative oncogenomic studies identified FBXW7 and PTEN to be commonly deleted both in murine lymphomas and in human T-cell acute lymphoblastic leukaemia/lymphoma (T-ALL).
The prognostic impact of PTEN loss is therefore linked to the underlying type of genomic abnormality, both in adult and paediatric T-ALLs, demonstrating that detailed analysis of the type of abnormality type would be useful to refine risk stratification.
NOTCH and phosphatidylinositide 3-kinase/phosphatase and tensin homolog deleted on chromosome ten/AKT/mammalian target of rapamycin (mTOR) signaling in T-cell development and T-cell acute lymphoblastic leukemia.
Different murine knockout models recapitulating the development of T-ALL have demonstrated that PTEN abnormalities are at the hub of an intricate oncogenic network sustaining and driving leukemia development by activating several signaling cascades associated with drug-resistance and poor outcome.
These data document the negative prognostic impact of JAK/STAT and RAS/PTEN mutations in T-cell acute lymphoblastic leukemia and suggest the potential clinical application of JAK and PI3K/mTOR inhibitors in patients harboring mutations in these pathways.
Regulation of PI3K signaling in T-cell acute lymphoblastic leukemia: a novel PTEN/Ikaros/miR-26b mechanism reveals a critical targetable role for PIK3CD.
GSI treatments increased AKT-Thr(308) phosphorylation and signaling in PTEN-deficient, GSI-resistant T-ALL cell lines (Jurkat, CCRF-CEM, and MOLT3), suggesting that Notch1 represses AKT independent of its PTEN transcriptional effects.
These results indicate that PTEN genomic aberrations and the biologically consequential PTEN inactivation contribute to adverse therapy response in T-ALL patients; PTEN status as a biomarker may contribute to the development of new molecularly-defined stratification algorithms.
We analyzed the effect of PTEN inactivation and its interaction with NOTCH1 activation on treatment response and long-term outcome in 301 ALL-BFM treated children with T-cell acute lymphoblastic leukemia.
This study explores the regulation and importance of System L amino acid transport in a murine model of T-cell acute lymphoblastic leukemia (T-ALL) caused by deletion of phosphatase and tensin homolog deleted on chromosome 10 (PTEN).
Due to the central role of PTEN-AKT signaling and in the resistance to NOTCH1 inhibition, AKT inhibitors may be a promising addition to current treatment protocols for T-cell acute lymphoblastic leukemia.
Here we show that PTEN inactivation in human T cell acute lymphoblastic leukemia (T-ALL) cells is not always synonymous with PTEN gene lesions and diminished protein expression.
Loss of PTEN and constitutive activation of AKT in T-ALL induce increased glucose metabolism and bypass the requirement of NOTCH1 signaling to sustain cell growth.
We found that transformed cells from a murine PTEN-deficient T-cell lymphoma model and from T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/T-LL) cell lines overexpress CD71.
Here we show that human primary T-cell acute lymphoblastic leukemias expressing an αβT cell receptor are frequently deficient for phosphatase and tensin homolog protein (PTEN), and fail to respond strongly to T-cell receptor activation.
These data demonstrate that the presence of N/F mutations in the absence of RAS or PTEN abnormalities predicts good outcome in almost 50% of adult T-ALL.