A calcium- and calpain-dependent pathway determines the response to lenalidomide in myelodysplastic syndromes.
Despite the high response rates of individuals with myelodysplastic syndrome (MDS) with deletion of chromosome 5q (del(5q)) to treatment with lenalidomide (LEN) and the recent identification of cereblon (CRBN) as the molecular target of LEN, the cellular mechanism by which LEN eliminates MDS clones remains elusive. Here we performed an RNA interference screen to delineate gene regulatory networks that mediate LEN responsiveness in an MDS cell line, MDSL. We identified GPR68, which encodes a G-protein-coupled receptor that has been implicated in calcium metabolism, as the top candidate gene for modulating sensitivity to LEN. LEN induced GPR68 expression via IKAROS family zinc finger 1 (IKZF1), resulting in increased cytosolic calcium levels and activation of a calcium-dependent calpain, CAPN1, which were requisite steps for induction of apoptosis in MDS cells and in acute myeloid leukemia (AML) cells. In contrast, deletion of GPR68 or inhibition of calcium and calpain activation suppressed LEN-induced cytotoxicity. Moreover, expression of calpastatin (CAST), an endogenous CAPN1 inhibitor that is encoded by a gene (CAST) deleted in del(5q) MDS, correlated with LEN responsiveness in patients with del(5q) MDS. Depletion of CAST restored responsiveness of LEN-resistant non-del(5q) MDS cells and AML cells, providing an explanation for the superior responses of patients with del(5q) MDS to LEN treatment. Our study describes a cellular mechanism by which LEN, acting through CRBN and IKZF1, has cytotoxic effects in MDS and AML that depend on a calcium- and calpain-dependent pathway.
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.
Jing
J
Fang
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.
Xiaona
X
Liu
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.
Lyndsey
L
Bolanos
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.
Brenden
B
Barker
Bone Marrow Transplant Unit, Azienda Ospedaliera Bianchi Melacrino Morelli, Reggio Calabria, Italy.
Carmela
C
Rigolino
Department of Hematology, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
Agostino
A
Cortelezzi
Hematology Unit, Azienda Ospedaliera Bianchi Melacrino Morelli, Reggio Calabria, Italy.
Esther N
EN
Oliva
Bone Marrow Transplant Unit, Azienda Ospedaliera Bianchi Melacrino Morelli, Reggio Calabria, Italy.
Maria
M
Cuzzola
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.
H Leighton
0000-0001-8162-6758
HL
Grimes
Celgene Corporation, Seville, Spain.
Celia
C
Fontanillo
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.
Kakajan
K
Komurov
Celgene Corporation, San Francisco, California, USA.
Kyle
K
MacBeth
Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA.|Department of Cancer Biology, University of Cincinnati, Cincinnati, Ohio, USA.
Daniel T
DT
Starczynowski
D048868:Adaptor Proteins, Signal Transducing; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics; D002154:Calpain / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D053263:Gene Regulatory Networks; D006801:Humans; D051740:Ikaros Transcription Factor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D007155:Immunologic Factors / Q000494:pharmacology*; D000077269:Lenalidomide; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism; D009190:Myelodysplastic Syndromes / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D034622:RNA Interference; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013792:Thalidomide / Q000031:analogs & derivatives* / Q000494:pharmacology; D044767:Ubiquitin-Protein Ligases
D048868:Adaptor Proteins, Signal Transducing; C502543:CRBN protein, human; D002135:Calcium-Binding Proteins; C486281:GPR68 protein, human; C497239:IKZF1 protein, human; D007155:Immunologic Factors; D043562:Receptors, G-Protein-Coupled; D051740:Ikaros Transcription Factor; D013792:Thalidomide; C033668:calpastatin; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D002154:Calpain; C484806:CAPN1 protein, human; D000077269:Lenalidomide; D002118:Calcium