Immune checkpoints PVR and PVRL2 are prognostic markers in AML and their blockade represents a new therapeutic option.

Immune checkpoints are promising targets in cancer therapy. Recently, poliovirus receptor (PVR) and poliovirus receptor-related 2 (PVRL2) have been identified as novel immune checkpoints. In this investigation we show that acute myeloid leukemia (AML) cell lines and AML patient samples highly express the T-cell immunoreceptor with Ig and ITIM domains (TIGIT) ligands PVR and PVRL2.

SHIP1, but not an AML-derived SHIP1 mutant, suppresses myeloid leukemia growth in a xenotransplantation mouse model.

Constitutive activation of the PI3K/AKT signaling pathway is found in ~50-70% of AML patients. The SH2-containing inositol 5-phosphatase 1 (SHIP1) is a negative regulator of PI3K/AKT signaling in hematopoietic cells. SHIP1 knockout mice develop a myeloproliferative syndrome and concomitant deletion of SHIP1 and the tumor suppressor PTEN leads to the development of lethal B-cell lymphomas.

Combined inhibition of GLI and FLT3 signaling leads to effective anti-leukemic effects in human acute myeloid leukemia.

Activation of the Hedgehog pathway has been implicated in the pathogenesis of several tumor types including myeloid leukemia. Previously we demonstrated that overexpression of Hedgehog downstream mediators GLI1/2 confers an adverse prognosis to patients with acute myeloid leukemia (AML) and is correlated with a FLT3 mutated status. To analyze a possible non-canonical activation of the Hedgehog pathway via FLT3 and PI3K, we performed blocking experiments utilizing inhibitors for FLT3 (sunitinib), PI3K (PF-04691502) and GLI1/2 (GANT61) in FLT3-mutated and FLT3 wildtype AML cell lines and primary blasts.

Deoxycytidine kinase is downregulated under hypoxic conditions and confers resistance against cytarabine in acute myeloid leukaemia.

Objectives: Leukaemia initiating cells reside within specialised niches in the bone marrow where they undergo complex interactions with different stromal cell types. The bone marrow niche is characterised by a low oxygen content resulting in high expression of hypoxia-inducible factor 1 α in leukaemic cells conferring a negative prognosis to patients with acute myeloid leukaemia (AML).

Methods And Results: In the current study, we investigated the impact of hypoxic vs.

Expression of Hedgehog Pathway Mediator GLI Represents a Negative Prognostic Marker in Human Acute Myeloid Leukemia and Its Inhibition Exerts Antileukemic Effects.

Purpose: The Hedgehog pathway plays an important role in stem-cell biology and malignant transformation. Therefore, we investigated the expression and prognostic impact of Hedgehog pathway members in acute myeloid leukemia (AML).

Experimental Design: Pretreatment samples from 104 newly diagnosed AML patients (AMLSG 07-04 trial) were analyzed by qPCR, and expression of Hedgehog family members was correlated with clinical outcome.