Staurosporine enhances ATRA-induced granulocytic differentiation in human leukemia U937 cells via the MEK/ERK signaling pathway.
Although all-trans retinoic acid (ATRA) is regarded as a prominent example of differentiation therapy, it is not effective for the treatment of other subtypes of acute myeloid leukemia (AML) beyond acute promyelocytic leukemia (APL). Therefore, new strategies need to be explored to extend the efficacy of ATRA-based therapy to non-APL AML patients. In the present study, staurosporine, a protein kinase C (PKC) pan-inhibitor, exhibited synergism with ATRA to promote granulocytic differentiation in poorly ATRA-sensitive U937 cells but not in ATRA unresponsive K562 and Kasumi cells. Staurosporine or the combined treatment did not affect PKC activity in U937 cells. Moreover, other selective PKC inhibitors, UCN-01, Go6976 or rottlerin failed to enhance ATRA‑induced granulocytic differentiation in U937 cells. Therefore, staurosporine-enhanced ATRA-induced granulocytic differentiation in U937 cells may be independent of PKC. Staurosporine activated mitogen‑activated protein kinase kinase (MEK) and extracellular signal‑regulated kinase (ERK). Meanwhile, staurosporine also enhanced ATRA-promoted upregulation of the protein level of CCAAT/enhancer‑binding protein β (C/EBPβ) and C/EBPε in U937 cells. Furthermore, blockade of MEK activation suppressed staurosporine‑enhanced differentiation as well as the elevated protein level of C/EBPs. Taken together, we concluded that staurosporine enhanced ATRA‑induced granulocytic differentiation in U937 cells via MEK/ERK-mediated modulation of the protein level of C/EBPs.
Shanghai Institute of Hematology and State Key Laboratory of Medical Genomics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P.R. China.
Lei
L
Shi
Shanghai Institute of Hematology and State Key Laboratory of Medical Genomics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P.R. China.
Xiang-Qin
XQ
Weng
Shanghai Institute of Hematology and State Key Laboratory of Medical Genomics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P.R. China.
Yan
Y
Sheng
Shanghai Institute of Hematology and State Key Laboratory of Medical Genomics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P.R. China.
Jing
J
Wu
Shanghai Institute of Hematology and State Key Laboratory of Medical Genomics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P.R. China.
Ming
M
Ding
Shanghai Institute of Hematology and State Key Laboratory of Medical Genomics, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, P.R. China.
Xun
X
Cai
D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis* / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020014:K562 Cells; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000096:biosynthesis / Q000235:genetics; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D019311:Staurosporine / Q000008:administration & dosage*; D014212:Tretinoin / Q000008:administration & dosage*; D020298:U937 Cells
D022782:CCAAT-Enhancer-Binding Protein-beta; C545012:CEBPB protein, human; D047428:Protein Kinase Inhibitors; D014212:Tretinoin; D020929:Mitogen-Activated Protein Kinase Kinases; D019311:Staurosporine