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The non-genotoxic activator of the p53 pathway Nutlin-3 shifts the balance between E2F7 and E2F1 transcription factors in leukemic cells
No full textThe effect of Nutlin-3, a small molecule inhibitor of the MDM2/p53 interaction, was investigated on the steady-state mRNA levels of the transcription factors E2F1 and E2F7 in a cohort of primary B-chronic lymphocytic leukemia (B-CLL) patient samples (n = 15) and normal peripheral blood mononuclear cells (PBMC). A 24-h treatment with Nutlin-3 significantly down-regulated E2F1 and promoted the concomitant up-regulation of E2F7 in both leukemic and normal cells. Our data suggest that the ability of Nutlin-3 to up-regulate E2F7 likely represents an important molecular determinant in the anti-proliferative activity of Nutlin-
SOCS1 is significantly up-regulated in Nutlin-3-treated p53 wild-type B chronic lymphocytic leukemia (BCLL) samples and shows an inverse correlation with miR-155
No full textThe basal SOCS1 mRNA levels were significantly lower in p53 mutated BJAB and MAVER leukemic cell lines with respect to p53 wild-type SKW6.4 and JVM-2 leukemic cell lines, p53 wild-type primary B chronic lymphocytic leukemia (B-CLL) cells and primary normal peripheral blood mononuclear cells (PBMC). Moreover, the MDM2 small molecule inhibitor Nutlin-3 significantly increased the levels of SOCS1 mRNA in both primary p53wild-type B-CLL cells as well as in p53 wild-type B leukemic cell lines, but not in p53mutated B leukemic cell lines nor in primary PBMC. Of note, a significant inverse correlation was observed between SOCS1 mRNA and miR-155 levels in Nutlin-3-treated primary B-CLL cells and PBMC, suggesting that the miRNA-155/SOCS1 axis represents a potentially important therapeutic target of Nutlin-3 in B-CLL. © 2012 Springer Science+Business Media, LLC
The MDM2 inhibitor Nutlins as an innovative therapeutic tool for the treatment of haematological malignancies
No full textAt variance to solid tumors, which show percentage of p53 deletions and/or mutations close to 50%, more than 80% of haematological malignancies express wild-type p53 at diagnosis. Therefore, activation of the p53 pathway by antagonizing its negative regulator murine double minute 2 (MDM2) might offer a new therapeutic strategy for the great majority of haematological malignancies. Recently, potent and selective small-molecule MDM2 inhibitors, the Nutlins, have been identified. Studies with these compounds have strengthened the concept that selective, non-genotoxic p53 activation might represent an alternative to the current cytotoxic chemotherapy. Interestingly, Nutlins not only are able to induce apoptotic cell death when added to primary leukemic cell cultures, but also show a synergistic effect when used in combination with the chemotherapeutic drugs commonly used for the treatment of haematological malignancies. Of interest, Nutlins also display non-cell autonomous biological activities, such as inhibition of vascular endothelial growth factor, stromal derived factor-1/CXCL12 and osteprotegerin expression and/or release by primary fibroblasts and endothelial cells. Moreover, Nutlins have a direct anti-angiogenic and anti-osteoclastic activity. Thus, Nutlins might have therapeutic effects by two distinct mechanisms: a direct cytotoxic effect on leukemic cells and an indirect non-cell autonomous effect on tumor stromal and vascular cells, and this latter effect might be therapeutically relevant also for treatment of haematological malignancies carrying p53 mutations
Reduced expression of cell cycle-associated genes in B lymphocytes purified from the peripheral blood of early-stage B chronic lymphocytic leukaemia patients
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TRAIL counteracts the proadhesive activity of inflammatory cytokines in endothelial cells by down-modulating CCL8 and CXCL10 chemokine expression and release
No full textExposure of endothelial cells to recombinant tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induced a modest (2-fold) increase of HL-60 cell adhesion as compared to TNF-alpha (40-fold) or interleukin 1beta (IL-1beta; 20-fold). However, pretreatment of endothelial cultures with TRAIL determined a significant reduction of the proadhesive activity induced by both TNF-alpha and IL-1beta. Unexpectedly, the antiadhesive activity of TRAIL was not due to interference with the nuclear factor kappaB (NF-kappaB)-mediated up-regulation of surface intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and E-selectin adhesion molecules in response to inflammatory cytokines. In searching for the molecular mechanism underlying this biologic activity of TRAIL, a cDNA microarray analysis was performed. TRAIL pretreatment variably down-modulated the mRNA steady-state levels of several TNF-alpha-induced chemokines, and, in particular, it abrogated the TNF-alpha-mediated up-regulation of CCL8 and CXCL10. Of note, the addition of optimal concentrations of recombinant CCL8 plus CXCL10 to endothelial cultures completely restored the proadhesive activity of TNF-alpha. Moreover, experiments performed with agonistic anti-TRAIL receptor antibodies demonstrated that both TRAIL-R1 and TRAIL-R2 contributed, although at different levels, to TRAIL-induced chemokine modulation. Taken together, our data suggest that TRAIL might play an important role in modulating leukocyte/endothelial cell adhesion by selectively down-regulating CCL8 and CXCL10 chemokines
The oncogene DEK promotes leukemic cell survival and is downregulated by both nutlin-3 and chlorambucil in B-chronic lymphocytic leukemic cells
No full textPURPOSE: To characterize the role of the oncogene DEK in modulating the response to either Nutlin-3, a small-molecule inhibitor of the MDM2/p53 interaction, orchlorambucil in primary B-chronic lymphocytic leukemia (B-CLL) cells.
EXPERIMENTAL DESIGN: DEK mRNA and protein levels were evaluated in primary B-CLL samples (n = 21), p53(wild-type) SKW6.4, p53(mutated) BJAB lymphoblastoid cell
lines, and normal CD19(+) B lymphocytes-treated Nutlin-3 or chlorambucil (10 micromol/L, each). Knocking down experiments with either p53 or DEK small interfering RNA (siRNA) were done to investigate the potential role of p53 in controlling the expression of DEK and the role of DEK in leukemic cell
survival/apoptosis. RESULTS: Both Nutlin-3 and chlorambucil downregulated DEK in primary B-CLL samples (n = 21) and SKW6.4 but not in BJAB cells. Knocking down p53 attenuated the effect of Nutlin-3 on DEK expression, whereas knocking down
DEK significantly increased both spontaneous and Nutlin-3-induced apoptosis. Conversely, counteracting DEK downmodulation by using p53 small interfering RNA
reduced Nutlin-3-mediated apoptosis. On the other hand, Nutlin-3 potently induced p53 accumulation, but it did not affect DEK levels in normal CD19(+) B lymphocytes. CONCLUSIONS: These data show that the downregulation of DEK in response to either Nutlin-3 or chlorambucil represents an important molecular
determinant in the cytotoxic response of leukemic cells, and suggest that strategies aimed to downregulate DEK might improve the therapeutic potential of these drugs
Mesenchymal stem cells-derived vascular smooth muscle cells release abundant levels of osteoprotegerin
No full textAlthough several studies have shown that the serum levels of osteoprotegerin (OPG) are significantly elevated in patients affected with atherosclerotic lesions in coronary and peripheral arteries, the cellular source and the role of OPG in the physiopathology of atherosclerosis are not completely defined. Therefore, we aimed to investigate the potential contribution of mesenchymal stem cells in the production/release of OPG. OPG was detectable by immunohistochemistry in aortic and coronary atherosclerotic plaques, within or in proximity of intimal vascular smooth muscle cells (SMC). In addition, bone marrow mesenchymal stem cell (MSC)-derived vascular SMC as well as primary aortic SMC released in the culture supernatant significantly higher levels of OPG with respect to MSC-derived endothelial cells (EC) or primary aortic EC. On the other hand, in vitro exposure to full-length human recombinant OPG significantly increased the proliferation rate of aortic SMC cultures, as monitored by bromodeoxyuridine incorporation. Taken together, these data suggest that OPG acts as an autocrine/paracrine growth factor for vascular SMC, which might contribute to the progression of atherosclerotic lesions. ©2009 European Journal of Histochemistry
Activation of the p53 pathway down-regulates the osteoprotegerin expression and release by vascular endothelial cells
No full textIt has been shown that the expression of osteoprotegerin (OPG) is up-regulated in tumor-associated endothelial cells as well as in the sera of patients affected by both solid tumors and hematological malignancies. We now report that sera of p53(-/-) mice contain higher levels of OPG with respect to p53(+/+) mice and that endothelial cells, in which p53 was knocked-down by siRNA, release increased levels of OPG with respect to mock-transfected cells. Conversely, activation of the p53 pathway by the MDM2 small molecule antagonist Nutlin-3 significantly attenuated both spontaneous and tumor necrosis factor (TNF)-alpha-induced OPG mRNA and protein release in endothelial cell cultures. OPG promoter functional assays and chromatin immunoprecipitation experiments revealed inhibitory effects of Nutlin-3 on the TNF-alpha-induced NF-kappaB DNA binding activity to the OPG promoter. Since OPG inhibits the pro-tumoricidal activity of TNF-related apoptosis inducing ligand (TRAIL), our findings suggest that, besides its well-documented functions within the malignant cancer cells, the ability of p53 to down-modulate OPG production by endothelial cells may be an additional important mechanism whereby it exerts non-cell-autonomous tumor suppression function
Nutlin-3 downregulates the expression of the Oncogene TCL1 in primary B Chronic Lymphocytic Leukemic cells.
No full textPURPOSE: The oncogene TCL1 plays a key role in the development of B chronic lymphocytic leukemia (B-CLL), but it is not known whether TCL1 could be modulated by therapeutic approaches.
EXPERIMENTAL DESIGN: B-CLL patient samples (n = 35) and B leukemic cell lines (EHEB, JVM2, JVM3, MEC1, MEC2, and BJAB) with different p53 status were exposed to Nutlin-3, a small-molecule inhibitor of the p53-MDM2 interaction. Modulations of the steady-state mRNA levels of TCL1 were analyzed by quantitative real-time PCR and Western blotting in both primary B-CLL samples and leukemic cell lines. In addition, transfection experiments with either p53 siRNA or with a TCL1 expression plasmid were carried out in the EHEB B-CLL cell line.
RESULTS: Upon ex vivo treatment with Nutlin-3, TCL1 was significantly (P < 0.05) decreased in 23 of 28 B-CLL p53(wild-type). The functionality of the p53 pathway in the same leukemic cell samples was underscored by the concomitant ability of Nutlin-3 to significantly (P < 0.05) upregulate the p53 target gene MDM2 in the p53(wild-type) leukemic cells. The dependence of TCL1 downregulation by a functional p53 pathway was confirmed in a panel of B lymphoblastoid cell lines and by p53 knockdown experiments with p53 siRNA. The importance of TCL1 in promoting leukemic cell survival was underscored in transfection experiments, in which TCL1 overexpression significantly counteracted the Nutlin-3-mediated induction of apoptosis in EHEB.
CONCLUSIONS: Our data indicate that the Nutlin-3 downregulates TCL1 mRNA and protein, which likely represents an important molecular determinant in the proapoptotic activity of Nutlin-3. Clin Cancer Re
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