Absence of IL-12Rβ2 in CD33(+)CD38(+) pediatric acute myeloid leukemia cells favours progression in NOD/SCID/IL2RγC-deficient mice

The IGF2/IGF1R/Nanog Signaling Pathway Regulates the Proliferation of Acute Myeloid Leukemia Stem Cells

Acute myeloid leukemia is an aggressive disease characterized by clonal proliferation and differentiation into immature hematopoietic cells of dysfunctional myeloid precursors. Accumulating evidence shows that CD34⁺CD38^- leukemia stem cells (LSCs) are responsible for drug resistance, metastasis, and relapse of leukemia. In this study, we found that Nanog, a transcription factor in stem cells, is significantly overexpressed in CD34⁺ populations from patients with acute myeloid leukemia and in LSCs from leukemia cell lines. Our data demonstrate that the knockdown of Nanog inhibited proliferation and induced cell cycle arrest and cell apoptosis. Moreover, Nanog silencing suppressed the leukemogenesis of LSCs in mice. In addition, we found that these functions of Nanog were regulated by the insulin-like growth factor receptor (IGF1R) signaling pathway. Nanog overexpression rescued the colony formation ability of LSCs treated with picropodophyllin (PPP), an IGF1R inhibitor. By contrast, knockdown of Nanog abolished the effects of IGF2 on the colony formation ability of these LSCs. These findings suggest that the IGF2/IGF1R/Nanog signaling pathway plays a critical role in LSC proliferation.

IL-25 dampens the growth of human germinal center-derived B-cell non Hodgkin Lymphoma by curtailing neoangiogenesis

Interleukin (IL)-25, a member of the IL-17 cytokine superfamily, is produced by immune and non-immune cells and exerts type 2 pro-inflammatory effects in vitro and in vivo. The IL-25 receptor(R) is composed of the IL-17RA/IL-17RB subunits. Previous work showed that germinal centre (GC)-derived B-cell non Hodgkin lymphomas (B-NHL) expressed IL-17AR, formed by IL-17RA and IL-17RC subunits, and IL-17A/IL-17AR axis promoted B-NHL growth by stimulating neoangiogenesis. Here, we have investigated expression and function of IL-25/IL-25R axis in lymph nodes from human GC-derived B-NHL, i.e. Follicular Lymphoma (FL,10 cases), Diffuse Large B Cell Lymphoma (6 cases) and Burkitt Lymphoma (3 cases). Tumor cells expressed IL-25R and IL-25 that was detected also in non-malignant cells by flow cytometry. Immunohistochemical studies confirmed expression of IL-25R and IL-25 in FL cells, and highlighted IL-25 expression in bystander elements of the FL microenvironment. IL-25 i) up-regulated phosphorylation of NFkBp65, STAT-1 and JNK in B-NHL cells; ii) inhibited in vitro proliferation of the latter cells; iii) exerted anti-tumor activity in two in vivo B-NHL models by dampening expression of pro-angiogenic molecules as VEGF-C, CXCL6 and ANGPT3. In conclusion, IL-25, that is intrinsically pro-angiogenic, inhibits B-NHL growth by reprogramming the angiogenic phenotype of B-NHL cells.

miR-150 Suppresses the Proliferation and Tumorigenicity of Leukemia Stem Cells by Targeting the Nanog Signaling Pathway

Proliferation, a key feature of cancer cells, accounts for the majority of cancer-related diseases resulting in mortality. MicroRNAs (miRNAs) plays important post-transcriptional modulation roles by acting on multiple signaling pathways, but the underlying mechanism in proliferation and tumorigenicity is unclear. Here, we identified the role of miR-150 in proliferation and tumorigenicity in leukemia stem cells (LSCs; CD34+CD38- cells). miR-150 expression was significantly down-regulated in LSCs from leukemia cell lines and clinical samples. Functional assays demonstrated that increased miR-150 expression inhibited proliferation and clonal and clonogenic growth, enhanced chemosensitivity, and attenuated tumorigenic activity of LSCs in vitro. Transplantation animal studies revealed that miR-150 overexpression progressively abrogates tumor growth. Immunohistochemistry assays demonstrated that miR-150 overexpression enhanced caspase-3 level and reduced Ki-67 level. Moreover, luciferase reporter assays indicated Nanog is a direct and functional target of miR-150. Nanog silencing using small interfering RNA recapitulated anti-proliferation and tumorigenicity inhibition effects. Furthermore, miR-150 directly down-regulated the expression of other cancer stem cell factors including Notch2 and CTNNB1. These results provide insights into the specific biological behavior of miR-150 in regulating LSC proliferation and tumorigenicity. Targeting this miR-150/Nanog axis would be a helpful therapeutic strategy to treat acute myeloid leukemia.

Interleukin-17A promotes the growth of human germinal center derived non-Hodgkin B cell lymphoma

Interleukin (IL)-17A belongs to IL-17 superfamily and binds the heterodimeric IL-17 receptor (R)(IL-17RA/IL-17RC). IL-17A promotes germinal center (GC) formation in mouse models of autoimmune or infectious diseases, but the role of IL-17A/IL-17AR complex in human neoplastic GC is unknown. In this study, we investigated expression and function of IL-17A/IL-17AR in the microenvironments of 44 B cell non-Hodgkin lymphomas (B-NHL) of GC origin (15 follicular lymphomas, 17 diffuse large B cells lymphomas and 12 Burkitt lymphomas) and 12 human tonsil GC. Furthermore, we investigated the role of IL-17A in two in vivo models of GC B cell lymphoma, generated by s.c. injection of SU-DHL-4 and OCI-Ly8 cell lines in Severe combined immunodeficiency (SCID)/Non Obese Diabetic (NOD) mice. We found that: (i) B-NHL cell fractions and tonsil GC B cells expressed IL-17RA/IL-17RC, (ii) IL-17A signaled in both cell types through NF-kBp65, but not p38, ERK-1/2, Akt or NF-kBp50/105, phosphorylation, (iii) IL-17A was expressed in T cells and mast cells from neoplastic and normal GC microenvironments, (iv) IL-17A rendered tonsil GC B cells competent to migrate to CXCL12 and CXCL13 by downregulating RGS16 expression; (v) IL-17A stimulated in vitro proliferation of primary B-NHL cells; (vi) IL-17A (1 μg/mouse-per dose) stimulated B-NHL growth in two in vivo models by enhancing tumor cell proliferation and neo-angiogenesis. This latter effect depended on IL-17A-mediated induction of pro-angiogenic gene expression in tumor cells and direct stimulation of endothelial cells. These data define a previously unrecognized role of human IL-17A in promoting growth of GC-derived B-NHL and modulating normal GC B cell trafficking.

Human interleukin 23 receptor induces cell apoptosis in mammalian cells by intrinsic mitochondrial pathway associated with the down-regulation of RAS/mitogen-activated protein kinase and signal transducers and activators of transcription factor 3 signaling pathways

The composition of IL-23R complex is similar to that of the IL-12 receptor (IL-12R) complex with a shared IL-12R-β1 chain. The IL-12R-β1 heterodimerizes with IL-23R and IL-12R-β2 to form IL-23R and IL-12R complexes, respectively. The IL-12R-β2 has been shown to function as a tumor suppressor gene and apoptotic inducer. However, whether IL-23R also functions in cell apoptosis is currently unknown. In this study, we demonstrate for the first time that overexpression of IL-23R markedly induces cell apoptosis in both 293ET and HeLa cells. The activations of caspase 3 and caspase 9 are induced by IL-23R. Mechanistic study reveals that IL-23R markedly inhibits RAS/MAPK and STAT3 but not STAT1 and PI-3K/Akt signaling pathways in both 293ET and HeLa cells. Overexpression of IL-23R significantly up-regulates IL-12Rβ1 expression but not IL-23α and IL-12β expressions in both cell lines. Therefore, our data strongly indicates that IL-23R is able to induce cell apoptosis by activating the intrinsic mitochondrial pathways associated with the inhibition in RAS/MAPK and STAT3 activations in mammalian cells.

Targeting acute myeloid leukemia cells with cytokines

Review of data identifying IL-12 and IL-27 as potential therapeutic agents for pediatric AML by targeting leukemia initiating cells and/or blasts.

AML is a hematologic malignancy that represents 15–20% of all childhood acute leukemias and is responsible for more than one-half of pediatric leukemic deaths. The bulk tumor is continuously regenerated and sustained by rare leukemic ICs that proliferate slowly, thus resulting refractory to chemotherapeutic agents targeting highly proliferating cells within the tumor. Therefore, a complete eradication of the bulk tumor may depend on efficacy of therapies that target IC. In spite of the improvements in the treatment of AML, the difficulty to eradicate completely the disease incites research for innovative therapeutic approaches. In this regard, the role of cytokines in the treatment of AML has been investigated for many years, and some of them have been tested in clinical trials as a result of their immunomodulatory properties. Furthermore, recent preclinical studies highlighted the ability of the IL-12 superfamily cytokines as potent antileukemic agents that act directly on tumor cells and on leukemic IC, thus opening new perspectives for leukemic patient treatment. Here, we review the current knowledge about the antileukemic effects of cytokines, documented in preclinical and clinical studies, discussing their potential clinical application.