CD274 promotes cell cycle entry of leukemia-initiating cells through JNK/Cyclin D2 signaling

Abstract

BackgroundCD274 (programmed death ligand 1, also known as B7H1) is expressed in both solid tumors and hematologic malignancies and is of critical importance for the escape of tumor cells from immune surveillance by inhibiting T cell function via its receptor, programmed death 1 (PD-1). Increasing evidence indicates that functional monoclonal antibodies of CD274 may potently enhance the antitumor effect in many cancers. However, the role of CD274 in leukemia-initiating cells (LICs) remains largely unknown.MethodsWe established an MLL-AF9-induced acute myeloid leukemia (AML) model with wild-type (WT) and CD274-null mice to elucidate the role of CD274 in the cell fates of LICs, including self-renewal, differentiation, cell cycle, and apoptosis. RNA sequencing was performed to reveal the potential downstream targets, the results of which were further validated both in vitro and in vivo.ResultsIn silico analysis indicated that CD274 level was inversely correlated with the overall survival of AML patients. In Mac-1+/c-Kit+ mouse LICs, CD274 was expressed at a much higher level than in the normal hematopoietic stem cells (HSCs). The survival of the mice with CD274-null leukemia cells was dramatically extended during the serial transplantation compared with that of their WT counterparts. CD274 deletion led to a significant decrease in LIC frequency and arrest in the G1 phase of the cell cycle. Interestingly, CD274 is not required for the maintenance of HSC pool as shown in our previous study. Mechanistically, we demonstrated that the levels of both phospho-JNK and Cyclin D2 were strikingly downregulated in CD274-null LICs. The overexpression of Cyclin D2 fully rescued the loss of function of CD274. Moreover, CD274 was directly associated with JNK and enhanced the downstream signaling to increase the Cyclin D2 level, promoting leukemia development.ConclusionsThe surface immune molecule CD274 plays a critical role in the proliferation of LICs. The CD274/JNK/Cyclin D2 pathway promotes the cell cycle entry of LICs, which may serve as a novel therapeutic target for the treatment of leukemia.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-016-0350-6) contains supplementary material, which is available to authorized users.

JAM3 maintains leukemia-initiating cell self-renewal through LRP5/AKT/β-catenin/CCND1 signaling

“…10) or patients' samples, and revealed that several candidates are highly expressed on MA9 cells or LICs, including BTLA, CD244, JAM3, B7-H1, and B7-H4. Our subsequent study indicated that B7-H1 is also important for leukemogenesis (11). However, the functions of other surface molecules in leukemogenesis remain largely unknown.…”

“…Human primary AML cells were cultured in Stemspan basic medium (Stemcell Technologies) supplemented with 10 ng/ml human stem cell factor (SCF), 10 ng/ml human IL-3, and 10 ng/ml human IL-6 (all the growth factors were from PeproTech). In another experiment, JAM3-slienced human cord blood CD34 + cells were at T308; the pCDH-EF1a-T2A plasmid was provided by Chuanxin Huang, Shanghai Jiao Tong University School of Medicine) was cotransfected with pCL-ECO (2:1, for retroviral plasmid) or pMD2G and pSPAX2 (4:1:3, for lentiviral plasmid) into 293T cells (ATCC), and the resulting retroviral or lentiviral supernatant was collected for the infection of WT and Jam3-null leukemia cells, followed by transplantation into recipient mice as previously described (11). The expression levels of CCND1, β-catenin CN (S552), and AKT CN (T308) were further measured in WT, Jam3-null, and Ccnd1/β-catenin CN /AKT CN -overexpressing Jam3-null leukemia cells by immunoblotting.…”

Macrophage targeting in cancer

“…176 In cancer, CD47 is overexpressed in a wide variety of tumor types: from myeloid leukemia and non-Hodgkin's lymphoma (NHL), to solid tumors in bladder and breast cancer. 163,[178][179][180][181][182][183][184][185] Several in vitro studies have shown that blocking of CD47 with monoclonal antibodies enables macrophage phagocytosis of tumor cells. 163,178,180 Other studies have shown that CD47 abrogation significantly enhances the ability of macrophages to kill tumor cells via antibody-dependent cellular cytotoxicity (ADCC).…”

Is CD47 an innate immune checkpoint for tumor evasion?

“…Research has demonstrated overexpression of CD47 in nearly all types of tumors, some of which include acute myeloid leukemia, non-Hodgkin’s lymphoma, bladder cancer, and breast cancer [18–25]. While CD47 is implicated in the regulation of cancer cell invasion and metastasis [18, 26], its most well-studied and important function related to tumor development is prevention of phagocytosis via ligating with SIRPα on the surrounding phagocytes [18, 27, 28].…”