mTOR signaling is activated by FLT3 kinase and promotes survival of FLT3-mutated acute myeloid leukemia cells

Activating mutations of the FLT3 gene mediate leukemogenesis, at least in part, through activation of PI3K/AKT. The mammalian target of rapamycin (mTOR)-Raptor signaling pathway is known to act downstream of AKT. Here we show that the mTOR effectors, 4EBP1, p70S6K and rpS6, are highly activated in cultured and primary FLT3-mutated acute myeloid leukemia (AML) cells. Introduction of FLT3-ITD expressing constitutively activated FLT3 kinase further activates mTOR and its downstream effectors in BaF3 cells. We also found that mTOR signaling contributes to tumor cell survival, as demonstrated by pharmacologic inhibition of PI3K/AKT/mTOR, or total silencing of the mTOR gene. Furthermore, inhibition of FLT3 kinase results in downregulation of mTOR signaling associated with decreased survival of FLT3-mutated AML cells. These findings suggest that mTOR signaling operates downstream of activated FLT3 kinase thus contributing to tumor cell survival, and may represent a promising therapeutic target for AML patients with mutated-FLT3

Molecular status 36 months after TKI discontinuation in CML is highly predictive for subsequent loss of MMR-final report from AFTER-SKI

Non peer reviewe

Serum Soluble TACI, a BLyS Receptor, Is a Powerful Prognostic Marker of Outcome in Chronic Lymphocytic Leukemia

BLyS is involved in CLL biology and its low soluble serum levels related to a shorter time to first treatment (TFT). TACI is a BLyS receptor and can be shed from cells' surface and circulate in soluble form (sTACI). We investigated the impact of serum BLyS and sTACI levels at diagnosis in CLL patients and their relationship with disease parameters and patients' outcome. Serum BLyS was determined in 73 patients, while sTACI in 60. Frozen sera drawn at diagnosis were tested by ELISA. sTACI concentrations correlated with BLyS ( = −0.000021), b2-microglobulin ( = 0.005), anemia ( = −0.03), thrombocytopenia ( = 0.04), Binet stage ( = 0.02), and free light chains ratio ( = 0.0003). Soluble BLyS levels below median and sTACI values above median were related to shorter TFT ( = 0.0003 and 0.007). During a ten-year followup, sTACI levels, but not BLyS, correlated with survival ( = 0.048). In conclusion, we confirmed the prognostic significance of soluble BLyS levels with regard to TFT in CLL patients, and, more importantly, we showed for the first time that sTACI is a powerful prognostic marker, related to parameters of disease activity and staging and, more importantly, to TFT and OS

Cytogenetic complexity in chronic lymphocytic leukemia: definitions, associations and clinical impact

Recent evidence suggests that complex karyotype (CK) defined by the presence of 653 chromosomal aberrations (structural and/or numerical) identified by chromosome banding analysis (CBA) may be relevant for treatment decision-making in chronic lymphocytic leukemia (CLL). However, many challenges towards routine clinical application of CBA remain. In a retrospective study of 5290 patients with available CBA data, we explored both clinicobiological associations and the clinical impact of CK in CLL. We found that patients with 655 abnormalities, defined as high-CK, exhibit uniformly dismal clinical outcome, independently of clinical stage, TP53 aberrations (deletion of chromosome 17p and or TP53 mutations, TP53abs) and the expression of somatically hypermutated (M-CLL) or unmutated (U-CLL) immunoglobulin heavy variable genes (IGHV). Thus, they contrasted CK cases with 3 or 4 aberrations (low-CK and intermediate-CK, respectively) who followed aggressive disease courses only in the presence of TP53abs. At the other end of the spectrum, patients with CK and +12,+19 displayed an exceptionally indolent profile. Building upon CK, TP53abs and IGHV gene somatic hypermutation status, we propose a novel hierarchical model where patients with high-CK exhibit the worst prognosis, while M-CLL lacking CK or TP53abs as well as CK with +12,+19 show the longest overall survival. In conclusion, CK should not be axiomatically considered unfavorable in CLL, representing a heterogeneous group with variable clinical behavior. High-CK with 655 chromosomal aberrations emerges as prognostically adverse, independently of other biomarkers. Prospective clinical validation is warranted before finally incorporating high-CK in risk stratification of CLL

Macroalgal community response to re-oligotrophication in Saronikos Gulf

Peer reviewedPublisher PD