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


METHODS
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. Inhibition of GLI by GANT61 or shRNA was investigated in AML cells in vitro and in vivo.


RESULTS
Expression of receptors Smoothened and Patched-1 and their downstream mediators, GLI1, GLI2, and GLI3, was found in AML patients in contrast to Hedgehog ligands. GLI2 expression had a significant negative influence on event-free survival (EFS), relapse-free survival (RFS), and overall survival (OS; P = 0.037, 0.026, and 0.013, respectively) and was correlated with FLT3 mutational status (P < 0.001). Analysis of a second, independent patient cohort confirmed the negative impact of GLI2 on EFS and OS (P = 0.007 and 0.003, respectively; n = 290). Within this cohort, GLI1 had a negative prognostic impact (P < 0.001 for both EFS and OS). Although AML cells did not express Hedgehog ligands by qPCR, AML patients had significantly increased Desert Hedgehog (DHH) plasma levels compared with healthy subjects (P = 0.002), in whom DHH was presumably provided by bone marrow niche cells. Moreover, the GLI inhibitor GANT61 or knockdown of GLI1/2 by shRNA caused antileukemic effects, including induction of apoptosis, reduced proliferation, and colony formation in AML cells, and a survival benefit in mice.


CONCLUSIONS
GLI expression is a negative prognostic factor and might represent a novel druggable target in AML.
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Jasmin
J
Wellbrock
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Emily
E
Latuske
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Julian
J
Köhler
Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany.
Katharina
K
Wagner
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Hauke
H
Stamm
Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Eik
E
Vettorazzi
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Gabi
G
Vohwinkel
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Marianne
M
Klokow
Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany.
Roswitha
R
Uibeleisen
Center for Experimental Medicine, Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Patrick
P
Ehm
Research Department Cell and Gene Therapy, Clinic for Stem Cell Transplantation, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Kristoffer
K
Riecken
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Department of Tumor Biology, Center of Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Sonja
S
Loges
Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany.
Felicitas
F
Thol
Department of Transfusion Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Claudia
C
Schubert
Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Michael
M
Amling
Center for Experimental Medicine, Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Manfred
M
Jücker
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Carsten
C
Bokemeyer
Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany.
Michael
M
Heuser
Department of Hematology, Hemostasis, Oncology and Stem Cell Transplantation, Hannover Medical School, Hannover, Germany.
Jürgen
J
Krauter
Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology, Hubertus Wald University Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. fiedler@uke.de.
Walter
W
Fiedler
D000293:Adolescent; D000328:Adult; D000818:Animals; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis; D018572:Disease-Free Survival; D005260:Female; D053823:Hedgehog Proteins / Q000378:metabolism; D006801:Humans; D053208:Kaplan-Meier Estimate; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality; D008297:Male; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008875:Middle Aged; D009368:Neoplasm Transplantation; D011379:Prognosis; D016016:Proportional Hazards Models; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000235:genetics; D015398:Signal Transduction; D000072086:Smoothened Receptor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D016896:Treatment Outcome; D055815:Young Adult; D000071676:Zinc Finger Protein GLI1
D014408:Biomarkers, Tumor; C551027:GANT 61; C400551:GLI1 protein, human; D053823:Hedgehog Proteins; D011725:Pyridines; D011743:Pyrimidines; D043562:Receptors, G-Protein-Coupled; C491023:SMO protein, human; D000072086:Smoothened Receptor; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1