Search

The 3,4-methylenedioxy-alpha-pyrrolidinohexanophenone (MDPHP) is a synthetic cathinone closely related to 3,4-methylenedioxypyrovalerone (MDPV), one of the most common synthetic cathinones present in the “bath salts”. MDPHP has recently gained attention due to increasing seizures and involvement in human intoxications which occurred in Europe and Italy in the last years, but currently there is a lack of information about its pharmaco-toxicological effects. With the aim at filling this gap, the present study is endeavoured to (i) evaluate the effects of acute administration of MDPHP (0.01–20 mg/kg; i.p.) on behaviour, cardiorespiratory and cardiovascular parameters in CD-1 male mice, comparing them to those observed after administration of MDPV; (ii) predict the ADMET profile of the two analogues using the Plus ADMET Predictor®; (iii) present clinical data related to MDPHP and MDPV-induced intoxications recorded between 2011 and 2023 by the Pavia Poison Control Centre (PCC) − National Toxicology Information Centre (Istituti Clinici Scientifici Maugeri, IRCCS Pavia, Italy). Our results substantiated that MDPHP and MDPV similarly affect sensorimotor and behavioural responses in mice, importantly increased locomotion and induced aggressive behaviour, and, at higher dosage, increased heart rate and blood pressure. These findings are in line with those observed in humans, revealing severe toxidromes typically characterized by Central Nervous System (CNS) alterations (behavioural/neuropsychiatric symptoms), including psychomotor agitation and aggressiveness, cardiovascular and respiratory disorders (e.g. tachycardia, hypertension, dyspnoea), and other peripheral symptoms (e.g. hyperthermia, acidosis, rhabdomyolysis).

Purpose: To report the clinical outcomes of large diameter deep anterior lamellar keratoplasty (DALK) and converted two-piece microkeratome-assisted mushroom keratoplasty (MK) for herpetic corneal scars. Methods: In this single-centre study, large diameter (9 mm) DALK was attempted in consecutive patients with herpetic corneal scars. In case of macroperforation or unsatisfactory clearance of the optical zone, the procedure was intraoperatively converted to two-piece microkeratome-assisted MK. Outcome measures were best spectacle-corrected visual acuity (BSCVA), refractive astigmatism, endothelial cell density (ECD), immunologic rejection, herpetic recurrence and graft failure rates in the two groups. Results: DALK was successfully performed in 98 of 120 eyes, while the remaining 22 eyes required intraoperative conversion to MK. At 5 years, mean logMAR BSCVA was 0.10 ± 0.12 in the DALK group and 0.09 ± 0.15 in the MK group (P= 0.75). Refractive astigmatism at 5 years was 2.8 ± 1.4 D in the DALK group and 3.0 ± 1.7 D in the MK group (P= 0.67). ECD was higher in the DALK group than in the MK group at all time points (P< 0.001), with a mean annual cell loss of 10.9% after MK and 4.2% after DALK. The 5-year risk for immunologic rejection (DALK: 3%, MK: 5%, P= 0.38), herpetic recurrence (DALK: 6%, MK: 9%, P= 0.38), and graft failure (DALK: 4%, MK: 5%, P= 0.75) were comparable in both groups. Conclusion: Large diameter (9 mm) DALK yields excellent visual and clinical outcomes in eyes with herpetic corneal scars. In case of intraoperative complications, DALK can be converted to two-piece microkeratome-assisted MK to maximize the refractive benefit of a large diameter graft while minimizing the risk of endothelial failure.

OBJECTIVE--To evaluate the potential therapeutic effect of recombinant human tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) treatment in a model of type 1 diabetes. RESEARCH DESIGN AND METHODS--Recombinant TRAIL was added in vitro to primary human and mouse peripheral blood mononuclear cells (PBMCs) and isolated human islets to evaluate the expression of the immunoregulatory gene SOCS1. Diabetes was induced by five consecutive dally injections of low-concentration (50 mg/kg) streptozotocin (STZ) in C57 black mice (n = 24). A group of these mice (n = 12) was co-injected with recombinant TRAIL (20 µg/day) for 5 days, and the diabetic status (glycemia and body weight) was followed over time. After 6 weeks, circulating levels of insulin, TNF-α, and osteoprotegerin (OPG) were measured, and animals were killed to perform the histological analysis of the pancreas. RESULTS--The in vitro exposure of both PBMCs and human islets to recombinant TRAIL significantly upregulated the expression of SOCS1. With respect to STZ-treated animals, mice coinjected with STZ+TRAIL were characterized by 1) lower levels of hyperglycemia, 2) higher levels of body weight and insulinemia, 3) a partial preservation of pancreatic islets with normal morphology, and 4) a lower expression of both systemic (TNF-α and OPG) and pancreatic (vascular cell adhesion molecule [VCAM]-1) inflammatory markers. CONCLUSIONS--Overall, these data demonstrate that the administration of recombinant TRAIL ameliorates the severity of STZ-induced type 1 diabetes, and this effect was accompanied by the upregulation of SOCS1 expression., Wile a large amount of data are available bout tumor necrosis factor (TNF)-related optosis-inducing ligand (TRAIL) as an anticancer agent (1), some studies have suggested a potential role of endogenous [...]

The HIV-1 Tat protein is involved in a self-regulatory loop which partially protects cells with the tat gene from dying and promotes HIV transcription. Researchers permanently inserted HIV-1 tat genes into a variety of cells and inserted mock genes into control cells. When serum was removed from the culture to cause cell death, the tat-containing cells were partially protected but the control cells were not. However, when antibodies to Tat protein were added to the medium, the tat-containing cells died at the same rate as the control cells. In a similar fashion, tat genes promoted cell proliferation and HIV-1 transcription but these promotional effects disappeared when antibodies to Tat protein were added to the cell cultures. These cells produce a Tat protein that is released and then acts on the same cell to protect it and promote its growth.

Background: Sudden sensorineural hearing loss (SSNHL) is an abrupt loss of hearing, still idiopathic in most of cases. Several mechanisms have been proposed including genetic and epigenetic interrelationships also considering iron homeostasis genes, ferroptosis and cellular stressors such as iron excess and dysfunctional mitochondrial superoxide dismutase activity. Results: We investigated 206 SSNHL patients and 420 healthy controls for the following genetic variants in the iron pathway: SLC40A1− 8CG (ferroportin; FPN1), HAMP− 582AG (hepcidin; HEPC), HFEC282Y and H63D (homeostatic iron regulator), TFP570S (transferrin) and SOD2A16V in the mitochondrial superoxide dismutase-2 gene. Among patients, SLC40A1− 8GG homozygotes were overrepresented (8.25% vs 2.62%; P= 0.0015) as well SOD216VV genotype (32.0% vs 24.3%; P= 0.037) accounting for increased SSNHL risk (OR = 3.34; 1.54–7.29 and OR = 1.47; 1.02–2.12, respectively). Moreover, LINE-1 methylation was inversely related (r2= 0.042; P= 0.001) with hearing loss score assessed as pure tone average (PTA, dB HL), and the trend was maintained after SLC40A1− 8CG and HAMP− 582AG genotype stratification (ΔSLC40A1= + 8.99 dB HL and ΔHAMP= − 6.07 dB HL). In multivariate investigations, principal component analysis (PCA) yielded PC1 (PTA, age, LINE-1, HAMP, SLC40A1) and PC2 (sex, HFEC282Y, SOD2, HAMP) among the five generated PCs, and logistic regression analysis ascribed to PC1 an inverse association with moderate/severe/profound HL (OR = 0.60; 0.42–0.86; P= 0.0006) and with severe/profound HL (OR = 0.52; 0.35–0.76; P= 0.001). Conclusion: Recognizing genetic and epigenetic biomarkers and their mutual interactions in SSNHL is of great value and can help pharmacy science to design by pharmacogenomic data classical or advanced molecules, such as epidrugs, to target new pathways for a better prognosis and treatment of SSNHL.

ABSTRACTIntroduction: Progressive breakthroughs in nanomedicine have been instrumental for the clinical translation of actively targeted drug-delivery approaches. Besides storing large payloads of drugs within the nanoparticle core, the conjugation of targeting moieties confers specific targeting ability to the nanoplatforms. In this respect, clinical results suggest that actively targeted nanocarriers can exhibit an overall improved antitumor efficacy, minimizing off-target toxicity.Areas covered: This review article summarizes the advances in active targeting of nanocarriers to cancer cells. Specifically, we discuss the various types of nanocarriers, describe the receptors that are frequently overexpressed in solid tumors, and discuss how this approach can be used to improve clinical outcomes. We particularly focus on ongoing clinical trials of actively targeted nanoparticles that are yet to be clinically approved.Expert opinion: Further investment in active targeting will likely pose clinical benefits. We envisage a future requiring the use of longitudinal measures in the clinical setting to profile the patients that are likely to benefit from actively targeted nanocarriers. At the preclinical stage, a complete picture of intratumoral barriers combined with a quantitative approach of the intratumoral fate of nanomaterials will be instrumental in defining more effective strategies to improve their clinical translation.

Type 1 diabetes mellitus (T1DM) is an autoimmune disease, due to the immune-mediated destruction of pancreatic -cells, whose incidence has been steadily increasing during the last decades. Insulin replacement therapy can treat T1DM, which, however, is still associated with substantial morbidity and mortality. For this reason, great effort is being put into developing strategies that could eventually prevent and/or cure this disease. These strategies are mainly focused on blocking the immune system from attacking -cells together with functional islet restoration either by regeneration or transplantation. Recent experimental evidences suggest that TNFrelated apoptosis-inducing ligand (TRAIL), which is an immune system modulator protein, could represent an interesting candidate for the cure for T1DM and/or its complications. Here we review the evidences on the potential role of TRAIL in the management of T1DM.

This review focuses on TNF-related apoptosis-inducing ligand (TRAIL), also called Apo2 ligand, a protein belonging to the TNF superfamily. TRAIL can be found either in its transmembrane or circulating form, and its mostly studied peripheral effect is the induction of cellular apoptosis. Here, we discuss the evidences supporting the use of TRAIL as biomarker of cardiovascular diseases as well as the evidences showing the potential beneficial therapeutic effects of TRAIL on cardiovascular diseases and diabetes.

Multicellular organisms require apoptosis whereby the human body eliminates unnecessary and/or damaged cells. Apoptosis, or programmed cell death, can indeed be considered as a constitutive anti-cancer mechanism that seems to be defective in more than 50 of cancers. Molecular insights on the biology of the apoptotic process have led to the development of new anti-cancer strategies aiming at recovering and stimulating this process. Preclinical and clinical studies of our and other groups have demonstrated that targeting the extrinsic apoptotic pathway by various death receptors agonists is a safe and effective anti-cancer strategy, which thus may become a new cornerstone of cancer therapy. Here, we review the most recent acquisitions and patents on TRAIL or TRAIL mimetics, as well as the combination therapies that could be used with them.

Introduction:TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines, and shows promising therapeutic activity against solid tumors and lymphomas, in a variety of Phase I and II clinical trials. In contrast, primary leukemias have shown poor susceptibility to TRAIL-mediated cytotoxicity, suggesting the need for sensitizing TRAIL-resistant leukemic cells, by combining soluble recombinant TRAIL either with chemotherapeutic drugs, or with targeted small molecules.Areas covered:This review discusses potential therapeutic applications of combinations able to restore the sensitivity of leukemic cells to either recombinant TRAIL or anti-TRAIL-receptor agonistic antibodies for the treatment of hematological malignancies.Expert opinion:Up-to-date knowledge of the most innovative anti-leukemic therapies including functional screening of specific-sensitizers, enhancing TRAIL-mediated cytotoxicity. Strategies aimed to enhance TRAIL-mediated apoptosis, include the combination of novel sensitizers, functionally identified from libraries of pharmaceutically active, synthetic or naturally derived compounds. Other approaches aim to employ the administration of stem cells engineered to express TRAIL, in the leukemic stem cell niche, and promise to be a successful treatment with reduced specific toxicity.

Nutlin-3 is a small molecule inhibitor of the MDM2/p53 interaction, which leads to the non-genotoxic p53 stabilization, activation of cell cycle arrest and apoptosis pathways. A series of recent studies have strengthened the concept that selective, non-genotoxic p53 activation by Nutlin-3 might represent an alternative to the current cytotoxic chemotherapy, in particular for pediatric tumors and for hematological malignancies, which retain a high percentage of p53wild-type status at diagnosis. Like most other drugs employed in cancer therapy, it will be unlikely that Nutlin-3 will be used as a monotherapy. In this respect, Nutlin-3 shows a synergistic cytotoxic effect when used in combination with innovative drugs, such as TRAIL or bortozemib. Although Nutlin-3 is currently in phase I clinical trial for the treatment of retinoblastoma, its effects on normal tissues and cell types remain largely to be determined and will require further investigation in the future years.

Aberrant expression of microRNAs (miRNAs) has been associated with clinical outcome in patients with chronic lymphocytic leukemia (CLL). To identify a powerful and easily assessable miRNA bio-marker of prognosis and survival, we performed quantitative reverse-transcription polymerase chain reaction (qRT-PCR) profiling in 104 CLL patients with a well-defined chromosome 17p status, and we validated our findings with miRNA microarray data from an independent cohort of 80 patients. We found that miR-15a, miR-21, miR-34a, miR-155, and miR-181bwere differentially expressed between CLLs with chromosome 17p deletion and CLLs with normal 17p and normal karyotype, and that miR-181bwas down-regulated in therapy-refractory cases. miR-21expression levels were significantly higher in patients with poor prognosis and predicted overall survival (OS), and miR-181bexpression levels significantly predicted treatment-free survival. We developed a 21FK score (miR-21qRT-PCR, fluorescence in situ hybridization, Karyotype) to stratify patients according to OS and found that patients with a low score had a significantly longer OS time. When we evaluated the relative power of the 21FK score with the most used prognostic factors, the score was the most significant in both CLL cohorts. We conclude that the 21FK score represents a useful tool for distinguishing between good-prognosis and poor-prognosis CLL patients.

Aberrant expression of microRNAs (miRNAs) has been associated with clinical outcome in patients with chronic lymphocytic leukemia (CLL). To identify a powerful and easily assessable miRNA bio-marker of prognosis and survival, we performed quantitative reverse-transcription polymerase chain reaction (qRT-PCR) profiling in 104 CLL patients with a well-defined chromosome 17p status, and we validated our findings with miRNA microarray data from an independent cohort of 80 patients. We found that miR-15a, miR-21, miR-34a, miR-155, and miR-181b were differentially expressed between CLLs with chromosome 17p deletion and CLLs with normal 17p and normal karyotype, and that miR-181b was down-regulated in therapy-refractory cases. miR-21 expression levels were significantly higher in patients with poor prognosis and predicted overall survival (OS), and miR-181b expression levels significantly predicted treatment-free survival. We developed a 21FK score (miR-21 qRT-PCR, fluorescence in situ hybridization, Karyotype) to stratify patients according to OS and found that patients with a low score had a significantly longer OS time. When we evaluated the relative power of the 21FK score with the most used prognostic factors, the score was the most significant in both CLL cohorts. We conclude that the 21FK score represents a useful tool for distinguishing between good-prognosis and poor-prognosis CLL patients.

The small molecule inhibitor of the MDM2/p53 interaction Nutlin-3 significantly up-regulated the steady-state mRNA and protein levels of Notch1 in TP53wild-type(OCI, SKW6.4) but not in TP53deleted(HL-60) or TP53mutated(BJAB) leukemic cell lines. A direct demonstration that NOTCH1was a transcriptional target of p53 in leukemic cells was obtained in experiments carried out with siRNA for p53. Moreover, inhibition of Notch1 expression using Notch1-specific siRNA significantly increased cytotoxicity in TP53wild-typeleukemic cells. Of note, Nutlin-3 up-regulated Notch1 expression also in primary TP53wild-typeB-chronic lymphocytic leukemia (B-CLL) cells and the combined use of Nutlin-3 plus pharmacological γ-secretase inhibitors of the Notch signaling showed a synergistic cytotoxicity in both TP53wild-typeleukemic cell lines and primary B-CLL cells. A potential drawback of γ-secretase inhibitors was their ability to enhance osteoclastic maturation of normal circulating preosteoclasts induced by RANKL + M-CSF. Notwithstanding, Nutlin-3 completely suppressed osteoclastogenesis irrespective of the presence of γ-secretase inhibitors. Taken together, these data indicate that the p53-dependent up-regulation of Notch1 in response to Nutlin-3 represents an antiapoptotic feedback mechanism able to restrain the potential therapeutic efficacy of Nutlin-3 in hematologic malignancies. Therefore, therapeutic combinations of Nutlin-3 + γ-secretase inhibitors might potentiate the cytotoxicity of Nutlin-3 in p53wild-typeleukemic cells.

At 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.

It 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 hematologic 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-α (TNF-α)–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-α-induced NF-κB DNA binding activity to the OPG promoter. Because OPG inhibits the pro-tumoricidal activity of TNF-related apoptosis-inducing ligand, 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.

We have investigated the effect of combined treatment with CpG‐oligodeoxynucleotide (CpG‐ODN) plus Nutlin‐3, a small molecule inhibitor of the murine double minute 2/p53 interaction, on the immune activation, cell cycle progression, and apoptosis of peripheral blood B chronic lymphocytic leukemia (B‐CLL) cells. CpG‐ODN induced a robust up‐regulation of immune activation markers (CD54, CD69, CD80, CD86, MHC‐II) in Zap70highand Zap70lowB‐CLL samples. Although cotreatment of B‐CLL cells with CpG‐ODN + Nutlin‐3 did not interfere with such immune activation, CpG‐ODN potentiated the Nutlin‐3‐mediated induction of the death receptors CD95 and TRAIL receptor 2. Importantly, treatment with CpG‐ODN did not interfere with the ability of Nutlin‐3 to inhibit cell cycle progression and to induce apoptosis. Thus, a therapeutic regimen including CpG‐ODN plus Nutlin‐3 might have the advantage to preserve the immune activation of B‐CLL cells while restraining the prosurvival/proliferative potential of CpG‐ODN treatment.

This review will focus on the emerging role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)/TRAIL-receptors in the pathophysiology of hematopoiesis and on the potential therapeutic applications of either recombinant TRAIL or anti-TRAIL-R1/-R2 agonistic antibodies for the treatment of hematological malignancies.

Recombinant osteoprotegerin (OPG) promoted the adhesion of both primary polymorphonuclear neutrophils (PMNs) and leukemic HL60 cells to endothelial cells. Leukocyte/endothelial cell adhesion was promoted by short (peak at 1 hour) preincubation of either endothelial cells or PMNs with OPG, and the peak of proadhesive activity was observed in the same range of OPG concentrations detected in the sera of patients affected by cardiovascular diseases. Although the cognate high-affinity ligands for OPG, membrane receptor activator of nuclear factor-κB ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), were detected at significant levels on both PMNs and HL60 cells, they were not expressed on the surface of endothelial cells. However, preincubation of OPG with heparin abrogated its proadhesive activity, whereas pretreatment of endothelial cells with chondroitinase plus heparinases significantly decreased the proadhesive activity of OPG. Taken together, these findings suggest the involvement of both the ligand binding and the N-terminal heparin-binding domains of OPG in mediating its pro-adhesive activity. The relevance of these in vitro findings was underscored by in vivo experiments, in which the topical administration of recombinant OPG increased leukocyte rolling and adhesion to rat mesenteric postcapillary venules. Our data suggest that a pathological increase of OPG serum levels might play an important role in promoting leukocyte/endothelial cell adhesion.

To potentiate the response of acute myeloid leukemia (AML) to TRAIL cytotoxicity, we have adopted a strategy of combining nutlin-3, a potent non-genotoxic activator of the p53 pathway, with recombinant TRAIL. The rationale for using such a combination was that deletions and/or mutations of the p53 gene occur in only 5-10% of AML and that TRAIL and nutlin-3 activate the extrinsic and intrinsic pathways of apoptosis, respectively. TRAIL induced a rapid increase of apoptosis when added to OCI M4-type and MOLM M5- type AML cells, carrying a wild-type p53, as well as to NB4 M3-type AML, carrying a mutated p53. On the other hand, the small molecule activator of the p53 pathway nutlin-3 induced p53 accumulation, cell cycle arrest and a slow progressive increase of apoptosis in OCI and MOLM but not in NB4. Of note, nutlin-3 up-regulated the surface expression of TRAIL-R2 and synergized with TRAIL in inducing apoptosis in OCI and MOLM as well as in primary M4-type and M5-type AML blasts, but not in NB4 cells. Moreover, while nutlin- 3 up-regulated the expression of cyclin dependent kinase inhibitor p21, a p53-target gene mediating cell cycle block and showing antiapoptotic activity, the simultaneous addition of TRAIL plus nutlin-3 induced the caspase-dependent cleavage of p21. The relevance of p21 down-regulation for sensitizing AML cells to apoptosis was underscored in knocking-down experiments with small interfering RNAs. Our data suggest that the combined treatment of nutlin-3 plus TRAIL might offer a novel therapeutic strategy for AML.

Serum osteoprotegerin (OPG) is significantly increased in diabetic patients, prompting expanded investigation of the correlation between OPG production/release and glycemic levels. Serum levels of OPG, but not of its cognate ligand receptor activator of nuclear factor-κB ligand (RANKL), were significantly increased in type 2 diabetes mellitus patients compared with healthy blood donors. Serum OPG was also significantly elevated in a subgroup of recently diagnosed diabetic patients (within 2 years). The relationship between serum OPG and diabetes mellitus onset was next investigated in apoE-null and littermate mice. Serum OPG increased early after diabetes induction in both mouse strains and showed a positive correlation with blood glucose levels and an inverse correlation with the levels of free (OPG-unbound) RANKL. The in vitroaddition of tumor necrosis factor-α to human vascular endothelial cells, but not human peripheral blood mononuclear cells, markedly enhanced OPG release in culture. In contrast, high glucose concentrations did not modulate OPG release when used alone or in association with tumor necrosis factor-α. Moreover, the ability of soluble RANKL to activate the extracellular signal-regulated kinase/mitogen-activated protein kinase and endothelial nitric-oxide synthase pathways in endothelial cells was neutralized by preincubation with recombinant OPG. Altogether, these findings suggest that increased OPG production represents an early event in the natural history of diabetes mellitus, possibly contributing to disease-associated endothelial cell dysfunction.

Deletions and/or mutations of p53 are relatively rare and late events in the natural history of B-cell chronic lymphocytic leukemia (B-CLL). However, it is unknown whether p53 signaling is functional in B-CLL and if targeted nongenotoxic activation of the p53 pathway by using nutlin-3, a small molecule inhibitor of the p53/MDM2 interaction, is sufficient to kill B-CLL cells. In vitro treatment with nutlin-3 induced a significant cytotoxicity on primary CD19+ B-CLL cells, but not on normal CD19+ B lymphocytes, peripheral-blood mononuclear cells, or bone marrow hematopoietic progenitors. Among 29 B-CLL samples examined, only one was resistant to nutlin-3–mediated cytotoxicity. The induction of p53 by nutlin-3 in B-CLL samples was accompanied by alterations of the mitochondrial potential and activation of the caspase-dependent apoptotic pathway. Among several genes related to the p53 pathway, nutlin-3 up-regulated the steady-state mRNA levels of PCNA, CDKN1A/p21, GDF15, TNFRSF10B/TRAIL-R2, TP53I3/PIG3, and GADD45. This profile of gene activation showed a partial overlapping with that induced by the genotoxic drug fludarabine. Moreover, nutlin-3 synergized with both fludarabine and chlorambucil in inducing B-CLL apoptosis. Our data strongly suggest that nutlin-3 should be further investigated for clinical applications in the treatment of B-CLL.

Evidence suggests that cyclooxygenase-2 (COX-2) increases tumorigenic potential by promoting resistance to apoptosis. Because B chronic lymphoid leukemia (B-CLL) cells exhibit a defective apoptotic response, we analyzed CD19+B lymphocytes purified from the peripheral blood of B-CLL patients. Microarray analysis showed a variable (up to 38-fold) increase in the steady-state mRNA levels of COX-2 in B-CLL lymphocytes compared with normal CD19+B lymphocytes. The up-regulation of COX-2 in B-CLL cells was confirmed by reverse transcriptase-polymerase chain reaction and Western blot analyses. Moreover, immunohistochemical analysis of B-CLL bone marrow infiltrates confirmed clear expression of COX-2 in leukemic cells. Ex vivotreatment with the COX-2 inhibitor NS-398 significantly decreased the survival of leukemic cells by increasing the rate of spontaneous apoptosis in 13 of 16 B-CLL samples examined, but it did not affect the survival of normal lymphocytes. Pretreatment with NS-398 significantly potentiated the cytotoxicity induced by chlorambucil in 8 of 16 B-CLL samples examined. Moreover, although recombinant tumor necrosis factor-related apoptosis inducing ligand (TRAIL)/Apo2L showed little cytotoxic effect in most B-CLL samples examined, pretreatment with NS-398 sensitized 8 of 16 B-CLL samples to TRAIL-induced apoptosis. Taken together, our data indicate that COX-2 overexpression likely represents an additional mechanism of resistance to apoptosis in B-CLL and that pharmacological suppression of COX-2 might enhance chemotherapy-mediated apoptosis.

It has been clearly established that osteoclasts, which play a crucial role in bone resorption, differentiate from hematopoietic cells belonging to the monocyte/macrophage lineage in the presence of macrophage-colony stimulating factor (M-CSF) and receptor activator of NF-?B ligand (RANKL). We have here investigated the M-CSF- and RANKL-induced osteoclastic differentiation of two distinct clones of the murine monocytic/macrophagic RAW 264.7 cell line, known as TIB-71 and CRL-2278, the latter cell clone being defective for the expression of the inducible nitric oxide synthase isoform in response to interferon-? or lipopolysaccharide. CRL-2278 cells demonstrated a more rapid osteoclastic differentiation than TIB-71 cells, as documented by morphology, tartrate-resistant acid phosphatase positivity, and bone resorption activity. The enhanced osteoclastic differentiation of CRL-2278 was accompanied by a higher rate of cells in the S/G2-M phases of cell cycle as compared to TIB-71. The analysis of nitric oxide synthase (NOS) isoforms clearly demonstrated that only neuronal NOS was detectable at high levels in CRL-2278 but not in TIB cells under all tested conditions. Moreover, the broad inhibitor of NOS activity L-NAME significantly inhibited osteoclastic differentiation of CRL-2278 cells. Altogether, these results demonstrate that a basal constitutive neuronal NOS activity positively affects the RANKL/M-CSF-related osteoclastic differentiation. © 2005 Wiley-Liss, Inc.

Exposure 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-α (40-fold) or interleukin 1β (IL-1β; 20-fold). However, pretreatment of endothelial cultures with TRAIL determined a significant reduction of the proadhesive activity induced by both TNF-α and IL-1β. Unexpectedly, the antiadhesive activity of TRAIL was not due to interference with the nuclear factor κB (NF-κB)-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-α-induced chemokines, and, in particular, it abrogated the TNF-α-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-α. 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.

Myelodysplastic syndromes (MDS) are characterized by impaired erythropoiesis, possibly caused by proapoptotic cytokines. We focused our study on the cytokine TRAIL (TNF-related apoptosis-inducing ligand), which has been shown to exhibit an anti-differentiation activity on erythroid maturation. Immunocytochemical analysis of bone marrow mononuclear cells (BMMC) showed an increased expression of TRAIL in MDS patients with respect to acute myeloid leukemia (AML) patients and normal BM donors. TRAIL expression was increased predominantly in myeloid precursors of granulocytic lineage and in a subset of monocytes and pro-erythroblasts. Significant levels of soluble TRAIL were released in 21 of 68 BMMC culture supernatants from MDS patients. On the other hand, TRAIL was detected less frequently in the culture supernatants of AML (4 of 33) and normal BMMC (0 of 22). Analysis of peripheral blood parameters revealed significantly lower levels of peripheral red blood cells and hemoglobin in the subset of patients whose BMMC released TRAIL in culture supernatants compared to the subgroup of patients who did not release TRAIL. Moreover, TRAIL-positive BMMC culture supernatants inhibited the differentiation of normal glycophorin A+ erythroblasts generated in serum-free liquid phase. Thus, increased expression and release of TRAIL at the bone marrow level is likely to impair erythropoiesis and to contribute to the degree of anemia, the major clinical feature of MDS.

TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF gene superfamily, which induces apoptosis through engagement of death receptors. TRAIL is unusual as compared to the other cytokines of this family, as it interacts with a complex system of receptors consisting of two pro-apoptotic death receptors (TRAIL-R1 and TRAILR2) and three decoy receptors (TRAIL-R3, TRAIL-R4 and osteoprotegerin). Moreover, with respect to other members of the TNF superfamily, such as CD95L and TNF-, TRAIL has generated great interest as a potential tumor-specific cancer therapeutic because as a stable soluble trimer it selectively induces apoptosis in many transformed cells but not in normal cells. Of note, TRAIL cytotoxicity is at least partially independent of the major systems involved in resistance to chemotherapy, such as p53 wild-type function and multidrug resistance (MDR) genes. Since one fundamental problem of most cancers is the development of multiple mechanisms of resistance, which progressively reduce or suppress the therapeutic efficacy of conventional chemotherapy, new therapeutic approaches that either restore the pro-apoptotic activity of chemotherapeutic drugs or by-pass the mechanisms of resistance are highly desirable. This review will focus on the potential of TRAIL for its application in the therapy of hematological malignancies, used either alone or in combination with chemotherapy. The scenario emerging from the literature is that the treatment and management of hematological malignancies will require the rational combination of TRAIL plus conventional or new drugs in a regimen that would optimize the anti-neoplastic activity in malignant cells resistant to chemotherapy through restoration of the proapoptotic activity of TRAIL.

The expression of tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) and TRAIL receptors was investigated in resting and cytokine-activated purified primary human natural killer (NK) and CD8+T cells. Resting NK and CD8+T cells expressed the mRNA for all TRAIL receptors, but TRAIL-R4 was the only receptor clearly detectable on the surface of both cell types. NK cells were activated by interleukin 2 (IL-2) or IL-15, whereas CD8+T cells were activated by phytohemagglutinin (PHA) + IL-2 followed by IL-2 alone for up to 10 days. On activation, both cell types rapidly expressed TRAIL-R2 and TRAIL-R3, whose expression peaked at day 10 of culture. TRAIL-R1, however, was never expressed at any time point examined, whereas the expression of TRAIL-R4, which showed a progressive increase in CD8+T cells, remained constant in NK cells. Notwithstanding the expression of TRAIL-R2, recombinant TRAIL did not show any cytotoxic activity on either NK or CD8+T cells. Both resting and activated NK and CD8+T cells were found to express high levels of the 2 isoforms of c-FLIP (cellular Fas-associated death domain protein [FADD]–like IL-1–converting enzyme [FLICE]–inhibitory protein). Small interference RNA-mediated inhibition of c-FLIP expression in NK cells abrogated their resistance to the apoptotic effect of soluble TRAIL. Thus, once activated the major cytotoxic effector cells are potentially sensitive to TRAIL but are physiologically protected from its apoptotic action by intracellular level of c-FLIP.

The expression of tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) and TRAIL receptors was investigated in resting and cytokine-activated purified primary human natural killer (NK) and CD8+ T cells. Resting NK and CD8+ T cells expressed the mRNA for all TRAIL receptors, but TRAIL-R4 was the only receptor clearly detectable on the surface of both cell types. NK cells were activated by interleukin 2 (IL-2) or IL-15, whereas CD8+ T cells were activated by phytohemagglutinin (PHA) + IL-2 followed by IL-2 alone for up to 10 days. On activation, both cell types rapidly expressed TRAIL-R2 and TRAIL-R3, whose expression peaked at day 10 of culture. TRAIL-R1, however, was never expressed at any time point examined, whereas the expression of TRAIL-R4, which showed a progressive increase in CD8+ T cells, remained constant in NK cells. Notwithstanding the expression of TRAIL-R2, recombinant TRAIL did not show any cytotoxic activity on either NK or CD8+ T cells. Both resting and activated NK and CD8+ T cells were found to express high levels of the 2 isoforms of c-FLIP (cellular Fas-associated death domain protein [FADD]–like IL-1–converting enzyme [FLICE]–inhibitory protein). Small interference RNA-mediated inhibition of c-FLIP expression in NK cells abrogated their resistance to the apoptotic effect of soluble TRAIL. Thus, once activated the major cytotoxic effector cells are potentially sensitive to TRAIL but are physiologically protected from its apoptotic action by intracellular level of c-FLIP.

The role of the tumor necrosis factor (TNF) superfamily member receptor activator of nuclear factor kappa B ligand (RANKL) in promoting the differentiation of osteoclasts has been extensively characterized. In this study, we have investigated the effect of TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily of cytokines, in osteoclastogenesis, by using human peripheral blood mononuclear cells and the RAW264.7 murine monocytic cell line. Both cell models differentiate into osteoclast-like cells in presence of RANKL plus macrophage-colony-stimulating factor (M-CSF), as evaluated in terms of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells and bone resorption activity. Unexpectedly, when added in culture in combination with RANKL plus M-CSF, TRAIL inhibited osteoclastic differentiation in both cell models. To investigate the molecular mechanism underlining such inhibitory activity, we analyzed the effect of TRAIL on the mitogen-activated protein kinases (MAPKs) pathways, which play a key role in osteoclastogenesis. Treatment with RANKL plus M-CSF activated both the ERK1/2 and p38/MAPK pathways, which are essential for proliferation and differentiation of preosteoclasts, respectively. Of note, the addition of TRAIL to RANKL plus M-CSF did not affect ERK1/2 but it profoundly inhibited p38/MAPK phosphorylation. Thus, our data demonstrate that TRAIL blocks osteoclastic differentiation and suggest that inhibition of the p38/MAPK pathway by TRAIL likely plays an important role in this process. (Blood. 2004;104:2044-2050)

In order to investigate the biologic activity of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) on human erythropoiesis, glycophorin A (GPA)+erythroid cells were generated in serum-free liquid phase from human cord blood (CB) CD34+progenitor cells. The surface expression of TRAIL-R1 was weakly detectable in the early-intermediate phase of erythroid differentiation (days 4-6; dim-intermediate GPA expression), whereas a clear-cut expression of TRAIL-R2 was observed through the entire course of erythroid differentiation (up to days 12-14; bright GPA expression). On the other hand, surface TRAIL-R3 and -R4 were not detected at any culture time. Besides inducing a rapid but small increase of apoptotic cell death, which was abrogated by the pan-caspase inhibitor z-VAD-fmk, the addition of recombinant TRAIL at day 6 of culture inhibited the generation of morphologically mature erythroblasts. Among the intracellular pathways investigated, TRAIL significantly stimulated the extracellular signal-regulated kinase 1/2 (ERK1/2) but not the p38/mitogen-activated protein kinase (MAPK) or the c-Jun NH2-terminal kinase (JNK) pathway. Consistently with a key role of ERK1/2 in mediating the negative effects of TRAIL on erythroid maturation, PD98059, a pharmacologic inhibitor of the ERK pathway, but not z-VAD-fmk or SB203580, a pharmacologic inhibitor of p38/MAPK, reverted the antidifferentiative effect of TRAIL on CB-derived erythroblasts.

Tumor necrosis factor (TNF)‐related apoptosis‐inducing ligand (TRAIL) and TNF‐α induced monocytic maturation of primary normal CD34‐derived myeloid precursors and of the M2/M3‐type acute myeloid leukemia HL‐60 cell line, associated to increased nuclear factor (NF)‐κB activity and nuclear translocation of p75, p65, and p50 NF‐κB family members. Consistently, both cytokines also induced the degradation of the NF‐κB inhibitors, IκBα and IκBɛ, and up‐regulated the surface expression of TRAIL‐R3, a known NF‐κB target. However, NF‐κB activation and IκB degradation occurred with different time‐courses, since TNF‐α was more potent, rapid, and transient than TRAIL. Of the two TRAIL receptors constitutively expressed by HL‐60 (TRAIL‐R1 and TRAIL‐R2), only the former was involved in IκB degradation, as demonstrated by using agonistic anti‐TRAIL receptor antibodies. Moreover, NF‐κB nuclear translocation induced by TRAIL but not by TNF‐α was abrogated by z‐IETD‐fmk, a caspase‐8‐specific inhibitor. The key role of NF‐κB in mediating the biological effects of TNF‐α and TRAIL was demonstrated by the ability of unrelated pharmacological inhibitors of the NF‐κB pathway (parthenolide and MG‐132) to abrogate TNF‐α‐ and TRAIL‐induced monocytic maturation. These findings demonstrate that NF‐κB is essential for monocytic maturation and is activated via distinct pathways, involving or not involving caspases, by the related cytokines TRAIL and TNF‐α.

In natural killer (NK) cells, interleukin-2 (IL-2) differentially regulates the expression of several transcription factors, including JunB and c-fos. The cAMP response element binding protein, CREB, is a key transcriptional regulator of a large number of genes containing the octanucleotide CRE consensus sequence in their upstream regulatory regions. We studied here thefunctional role of CREB in the IL-2-mediated transcriptional regulation of c-fos in human NK cells. Our results show that IL-2 activates CREB in human NK cells and that CREB activation hasa prominent regulatory role on the IL-2-induced expression of functional c-fos and AP-1 in NK cells. We identify two domains of the c-fos promoter, containing three CRE sites, which are critical for the transcriptional activity induced by IL-2. The first domain is located within the first 220 nucleotides of the c-fos promoter, while the second encompasses the nucleotides − 440 and − 220. Our results show that CREB has a relevant role in the cytokine-mediated activation of NK cells, and are particularly remarkable in the light of the several genes that are positively regulated by c-fos and AP-1, such as IFN-γ, IL-2 and GM-CSF genes.

Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) up‐regulated the expression of constitutive cyclooxygenase (COX)‐1 protein in HL‐60 cells without affecting COX‐2. The TRAIL‐mediated COX‐1 up‐regulation was accompanied by a significant increase of the PGE2synthesis and release, which was suppressed by the COX‐1 inhibitor valeryl salicylate but not by the COX‐2 inhibitor NS‐398. Experiments carried out by adding exogenous PGE2to HL‐60 cells indicated that PGE2was not involved in TRAIL cytotoxicity and rather showed a dose‐dependent protection against TRAIL‐induced apoptosis. Importantly, the ability of TRAIL to increase PGE2production was also observed in normal, human CD34‐derived myeloid cells and in freshly isolated peripheral blood CD14+monocytes. Moreover, in contrast to HL‐60 cells, primary, normal cells were not susceptible to TRAIL cytotoxicity. These data indicate that the ability of TRAIL to up‐regulate eicosanoid production and release is not confined to malignant leukemic cells, but it may also play a role in normal hematopoiesis.

Treatment of the human HL-60 cell line with tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) resulted in rapid (6-24 hours) cytotoxicity associated with progressive maturation of the surviving cells along the monocytic lineage. The occurrence of monocytic maturation was demonstrated by a significant increase of both CD14 and CD11b surface expression, the acquisition of morphologic features typical of mature monocytes, and phagocytic capacity in TRAIL-treated cultures. By using selective pharmacologic inhibitors, it was possible to demonstrate that activation of the caspase cascade played a crucial role in mediating TRAIL cytotoxicity and monocytic maturation of HL-60 cells. Moreover, experiments performed using agonistic polyclonal antibodies, which mimic the interactions between TRAIL and each TRAIL receptor, indicated that TRAIL-R1 was responsible for mediating the TRAIL-induced maturation. Importantly, the maturational effects of TRAIL were observed also in primary normal CD34+ cells, seeded in serum-free liquid cultures for 4 to 8 days in the presence of SCF + GM−CSF. After treatment with TRAIL for 3 additional days, a significant increase in CD14 and CD11b expression, coupled with an increased number of mature monocytes and macrophages, was noticed in the absence of cytotoxicity. These data disclose a novel role for TRAIL as a positive regulator of myeloid differentiation. Moreover, the dichotomous effect of TRAIL on malignant cells (early induction of apoptosis and monocytic maturation of the surviving cells) might have important therapeutic implications for the treatment of acute myeloid leukemia.

In this study, we have investigated the expression of phospholipase C‐β2 during the course of granulocytic differentiation of normal and malignant progenitors. As a model system, we used the NB4 cell line, a reliable in vitro model for the study of acute promyelocytic leukemia (APL), a variety of acute myeloid leukemia (AML) that responds to pharmacological doses of all trans‐retinoic acid (ATRA) by differentiating in a neutrophil‐like manner. We found that PLC‐β2, virtually absent in untreated NB4 cells, was strongly up‐regulated after ATRA‐induced granulocytic differentiation. Remarkably, using primary blasts purified from bone marrow of patients affected by APL successfully induced to remission by treatment with ATRA, we showed a striking correlation between the amount of PLC‐β2 expression and the responsiveness of APL blasts to the differentiative activity of ATRA. An increase of PLC‐β2 expression also characterized the cytokine‐induced granulocytic differentiation of CD34+normal hematopoietic progenitors. Taken together, these data show that PLC‐β2 represents a sensitive and reliable marker of neutrophil maturation of normal and malignant myeloid progenitors. Moreover, PLC‐β2 levels can predict the in vivo responsiveness to ATRA of APL patients.

Background: Heparin-induced thrombocytopenia (HIT) is a possible complication of heparin therapy that can evolve with life-threatening thromboembolism, for which early diagnosis is essential. However, the specific laboratory approach to the diagnosis of HIT is still controversial. Methods: Sera from 13 patients with HIT, from 15 patients with non-HIT thrombocytopenia, and from 10 normal subjects were used to compare nonfunctional and functional methods to detect anti-heparin:PF-4 antibodies and platelet activation. We used three enzyme-linked immunosorbent assays (ELISAs) and the particle gel immunoassay as nonfunctional tests, and platelet aggregometry, CD62p (p-selectin) phenotypical expression, and Annexin V binding as functional assays. Results: CD62p expression was positive in 85% of the cases and Annexin V was positive in 40% of the HIT cases examined. Aggregometry gave variable results that depend strongly on the donor. Conclusion: Functional tests for platelet activation are more reliable for HIT diagnosis than the nonfunctional tests. We conclude that the phenotypical expression of p-selectin detected by flow cytometry on activated platelets appears to be a good functional marker for the diagnosis of HIT and its possible thromboembolic complications. Cytometry (Comm. Clin. Cytometry) 46:290–295, 2001. © 2001 Wiley-Liss, Inc.

Human herpesvirus 7 (HHV-7) is endemic in the adult human population. Although HHV-7 preferentially infects activated CD4+ T lymphocytes, the consequence of T-cell infection for viral pathogenesis and immunity are still largely unknown. HHV-7 infection induces apoptosis mostly in uninfected bystander cells but not in productively infected CD4+ T cells. To dissect the underlying molecular events, the role of death-inducing ligands belonging to the tumor necrosis factor (TNF) cytokine superfamily was investigated. HHV-7 selectively up-regulated the expression of TNF-related apoptosis-inducing ligand (TRAIL), but not that of CD95 ligand or TNF-α in lymphoblastoid (SupT1) or primary activated CD4+ T cells. Moreover, in a cell-to-cell-contact assay, HHV-7–infected CD4+ T lymphocytes were cytotoxic for bystander uninfected CD4+ T cells through the TRAIL pathway. By contrast, HHV-7 infection caused a marked decrease of surface TRAIL-R1, but not of TRAIL-R2, CD95, TNF-R1, or TNF-R2. Of note, the down-regulation of TRAIL-R1 selectively occurred in cells coexpressing HHV-7 antigens that became resistant to TRAIL-mediated cytotoxicity. These findings suggest that the TRAIL-mediated induction of T-cell death may represent an important immune evasion mechanism of HHV-7, helping the virus to persist in the host organism throughout its lifetime.

Human herpesvirus 7 (HHV-7) is endemic in the adult human population. Although HHV-7 preferentially infects activated CD4+T lymphocytes, the consequence of T-cell infection for viral pathogenesis and immunity are still largely unknown. HHV-7 infection induces apoptosis mostly in uninfected bystander cells but not in productively infected CD4+T cells. To dissect the underlying molecular events, the role of death-inducing ligands belonging to the tumor necrosis factor (TNF) cytokine superfamily was investigated. HHV-7 selectively up-regulated the expression of TNF-related apoptosis-inducing ligand (TRAIL), but not that of CD95 ligand or TNF-α in lymphoblastoid (SupT1) or primary activated CD4+T cells. Moreover, in a cell-to-cell-contact assay, HHV-7–infected CD4+T lymphocytes were cytotoxic for bystander uninfected CD4+T cells through the TRAIL pathway. By contrast, HHV-7 infection caused a marked decrease of surface TRAIL-R1, but not of TRAIL-R2, CD95, TNF-R1, or TNF-R2. Of note, the down-regulation of TRAIL-R1 selectively occurred in cells coexpressing HHV-7 antigens that became resistant to TRAIL-mediated cytotoxicity. These findings suggest that the TRAIL-mediated induction of T-cell death may represent an important immune evasion mechanism of HHV-7, helping the virus to persist in the host organism throughout its lifetime.

Tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) induced both cytotoxic (apoptosis) and cytostatic (cell cycle perturbation) effects on the human myeloid K562 cell line. TRAIL stimulated caspase 3 and nitric oxide synthase (NOS) activities, and both pathways cooperate in mediating inhibition of K562 survival/growth. This was demonstrated by the ability of z-VAD-fmk, a broad inhibitor of effector caspases, and N-nitro-l-arginine methyl ester (L-NAME), an NOS pharmacologic inhibitor, to completely (z-VAD-fmk) or partially (L-NAME) suppress the TRAIL-mediated inhibitory activity. Moreover, z-VAD-fmk was able to block TRAIL-mediated apoptosis and cell cycle abnormalities and increase of NOS activity. The addition of the NO donor sodium nitroprusside (SNP) to K562 cells reproduced the cytostatic effect of TRAIL without inducing apoptosis. When TRAIL was associated to SNP, a synergistic increase of apoptosis and inhibition of clonogenic activity was observed in K562 cells as well as in other myeloblastic (HEL, HL-60), lymphoblastic (Jurkat, SupT1), and multiple myeloma (RPMI 8226) cell lines. Although SNP greatly augmented TRAIL-mediated antileukemic activity also on primary leukemic blasts, normal erythroid and granulocytic cells were less sensitive to the cytotoxicity mediated by TRAIL with or without SNP. These data indicate that TRAIL promotes cytotoxicity in leukemic cells by activating effector caspases, which directly lead to apoptosis and stimulate NO production, which mediates cell cycle abnormalities. Both mechanisms seem to be essential for TRAIL-mediated cytotoxicity.

The expression, cellular distribution, and activity of PIP2-specific phospholipase C (PLC) in healthy human gastric-mucosa cells have been recently studied in our laboratories and a direct evidence for an almost exclusive expression of PLC β isoforms, with the exception of PLC β4, has been provided. These results addressed our attention to possible modification of PLC expression and activity during neoplastic transformation of the human gastric mucosa. In the present article we present results indicating that PLC δ2 is markedly expressed in type II intestinal metaplasia and in the adenocarcinoma whereas traces of other PLC isoforms were sometime detected. Interestingly, we found that type I intestinal metaplasia was in the majority of the cases PLC δ2-negative, but when expressed, this type of metaplasia generally considered as benignant, always evolved toward neoplastic transformation. These results therefore readdress the question of surveillance of the patients with type I intestinal metaplasia and suggest that PLC δ2 expression might be a possible marker of gastric malignant transformation.

Cytotoxic activity of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL/Apo-2 ligand), used alone or in different combinations with either a low (1.5 Gy) or a high (15 Gy) single dose of ionizing radiation (IR), was investigated on erythroleukemic cells (K562, HEL, Friend, primary leukemic erythroblasts) and on primary CD34+-derived normal erythroblasts. Human recombinant TRAIL alone variably affected the survival/growth of erythroleukemic cells; K562 cells were the most sensitive. Moreover, all erythroleukemic cells were radio-resistant, as demonstrated by the fact that cytotoxicity was evident only after treatment with high-dose (15 Gy) IR. Remarkably, when IR and TRAIL were used in combination, an additive effect was noticed in all erythroleukemic cells. Augmentation of TRAIL-induced cell death by IR was observed with both low and high IR doses and required the sequential treatment of IR 3 to 6 hours before the addition of TRAIL. Conversely, both TRAIL and IR showed a moderate cytotoxicity on primary CD34+-derived normal erythroblasts when used alone, but their combination did not show any additive effect. Moreover, the cytotoxicity of IR plus TRAIL observed in erythroleukemic cells was accompanied by the selective up-regulation of the surface expression of TRAIL-R1 (DR4), and it was completely blocked by the z-Val-Ala-Asp (OMe)-CH2 (z-VAD-fmk) caspase inhibitor. On the other hand, the surface expression of TRAIL-R1 in CD34+-derived normal erythroblasts was unaffected by IR, which induced the up-regulation of the decoy TRAIL-R3. These data demonstrate that treatment with IR provides an approach to selectively sensitize erythroleukemic cells, but not normal erythroblasts, to TRAIL-induced apoptosis through the functional up-regulation of TRAIL-R1.

We have here investigated the effect of TNF-related apoptosis-inducing ligand (TRAIL), a new member of the TNF cytokine superfamily, on the survival of Jurkat lymphoblastoid cell lines stably transfected with plasmids expressing the wild-type or mutated (Cys22) human immunodeficiency virus type 1 (HIV-1) tat gene. Jurkat cells transfected with wild-type tat were resistant to TRAIL-mediated apoptosis, while Jurkat cells mock-transfected with the control plasmid or with a mutated nonfunctional tat cDNA were highly susceptible to TRAIL-mediated apoptosis. Also, pretreatment with low concentrations (10–100 ng/ml) of extracellular synthetic Tat protein partially protected Jurkat cells from TRAIL-mediated apoptosis. Taken together, these results demonstrated that endogenously expressed tat and, to a lesser extent, extracellular Tat block TRAIL-mediated apoptosis. Since it has been shown that primary lymphoid T cells purified from HIV-1-infected individuals are more susceptible than those purified from normal individuals to TRAIL-mediated apoptosis, our findings underscore a potentially important role of Tat in protecting HIV-1-infected cells from TRAIL-mediated apoptosis.

Stromal‐derived factor‐1α (SDF‐1α), the high‐affinity ligand of CXC‐chemokine receptor 4 (CXCR4), induced a progressive increase of apoptosis when added to the Jurkat CD4+/CXCR4+T cell line. The SDF‐1α‐mediated Jurkat cell apoptosis was observed in serum‐free or serum‐containing cultures, peaked at SDF‐1α concentrations of 10–100 ng/ml, required 3 days to take place, and was completely blocked by the z‐VAD‐fmk tripeptide caspase inhibitor. Although SDF‐1α did not modify the expression of TNF‐α or that of TNF‐RI and TNF‐RII, it increased the expression of surface Fas/APO‐1 (CD95) and intracellular Fas ligand (CD95L) significantly. Moreover, the ability of SDF‐1α to induce apoptosis was inhibited by an anti‐CD95 Fab′ neutralizing antibody. These findings suggest a role for SDF‐1α in the homeostatic control of CD4+T‐cell survival/apoptosis mediated by the CD95‐CD95L pathway.

The addition of low concentrations (0.1–1 nM) of extracellular HIV‐1 Tat protein to PC12 neuronal cells stimulated a rapid (peak at 5 min) elevation of the cAMP intracellular levels, which in turn induced the phosphorylation of CREB transcription factor (peak at 15 min) on serine‐133 (Ser‐133). On the contrary, at later time points (60–120 min) Tat induced a significant decline of intracellular cAMP with respect to the basal levels observed in control cells treated with bovine serum albumin. In blocking experiments performed with pharmacological inhibitors, Tat decreased the intracellular levels of cAMP and CREB Ser‐133 phosphorylation through a signal transduction pathway involving the sequential activation of phosphatidylinositol 3‐kinase, AKT, and cyclic nucleoside phosphodiesterases. Moreover, in transient transfection experiments, Tat inhibited transcription of CREB promoter in a manner strictly dependent on the presence of the cAMP‐responsive elements (CRE) in the CREB promoter. Consistently, the expression of endogenous CREB protein was significantly reduced in PC12 cells by prolonged (24–48 h) treatment with Tat. This decline in the expression of CREB, which plays an essential role in the survival and function of neuronal cells, anticipated a progressive increase of apoptosis in Tat‐treated cells. Although obtained in a neuronal cell line, our findings might help to explain some aspects of the pathogenesis of HIV‐1‐associated dementia.—Zauli, G., Milani, D., Mirandola, P., Mazzoni, M., Secchiero, P., Miscia, S., Capitani, S. HIV‐1 Tat protein downregulates CREB transcription factor expression in PC12 neuronal cells through a phosphatidylinositol 3‐kinase/AKT/cyclic nucleoside phosphodiesterase pathway. FASEB J.15, 483‐491 (2001)

Stromal derived factor‐1α (SDF‐1α), the high‐affinity ligand of CXC‐chemokine receptor 4 (CXCR4), was added to human CD34+hematopoietic progenitor cells that can be induced to differentiate along the monocytic or megakaryocytic lineages. In control liquid cell cultures supplemented with two different cytokine cocktails: stem cell factor (SCF), interleukin‐3 (IL‐3), macrophage‐colony stimulating factor (M‐CSF), and 10% fetal calf serum (FCS), or, SCF and thrombopoietin (TPO), the expression of surface CXCR4 progressively increased in both the CD14+monocytic and CD41+megakaryocytic lineages. While SDF‐1α caused only modest effects on cells of the monocytic lineage, it induced profound down‐regulation of CXCR4 in megakaryocytic cells at all stages of differentiation. Moreover, while SDF‐1α initially up‐regulated the early megakaryocytic antigen CD41, at later time points (days 12–16) it induced down‐regulation of the late megakaryocytic antigen CD42b. Consistently, at day 16, the number of mature megakaryocytes was significantly decreased in cultures supplemented with SDF‐1α. These findings indicate that, besides its primary role in regulating the retention of precursor cells in hematopoietic tissues, the SDF‐1α/CXCR4 system participates in the regulation of megakaryocytic development by stimulating the formation of immature megakaryoblasts and inhibiting the formation of mature megakaryocytes. Anat Rec 260:141–147, 2000. © 2000 Wiley‐Liss, Inc.

To investigate the tropism of the T-lymphotropic human herpesvirus 7 (HHV-7) for hematopoietic progenitors, cord blood CD34+ cells were inoculated in vitro with HHV-7 and then induced to differentiate along the granulocytic and erythroid lineages by the addition of appropriate cytokine cocktails. In semisolid assays, HHV-7 modestly affected the growth of committed (granulocytic/macrophagic and erythroid) progenitors, whereas it significantly decreased the number of pluripotent (granulocytic/erythroid/ monocytic/megakaryocytic) progenitors. Such inhibitory effect was completely abrogated by incubating HHV-7 inoculum with anti–HHV-7 neutralizing serum. In liquid cultures, HHV-7 hastened maturation along the myeloid but not the erythroid lineage, as demonstrated by the up-regulation of CD33 early myeloid antigen at day 7 of culture, and of CD15 and CD14 antigens at day 15. Moreover, HHV-7 messenger RNA was detected by reverse transcriptase–polymerase chain reaction (RT-PCR) in cells maturating along both the myeloid and the erythroid lineages. To evaluate the relevance of these in vitro findings, the presence of HHV-7 was investigated in bone marrow (BM) unfractionated mononuclear cells (MCs) as well as in purified CD34+ and CD34- cell subsets, obtained from 14 normal adult donors. HHV-7 DNA was detected by DNA-PCR in 4 of 7 BMMC samples, and it was found to be associated with both the CD34- (2 of 7) and the CD34+ (1 of 7) fractions. These data indicate that HHV-7 infects BM cells in vivo and shows the ability to affect the survival/differentiation of CD34+ hematopoietic progenitors in vitro by inhibiting more ancestral progenitors and perturbing the maturation of myeloid cells.

The impact of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) on normal hematopoietic development was investigated using adult peripheral blood CD34+ hematopoietic progenitor cells, induced to differentiate along the erythroid, megakaryocytic, granulocytic, and monocytic lineages by the addition of specific cytokine cocktails. TRAIL selectively reduced the number of erythroblasts, showing intermediate levels of glycophorin A (glycophorin Ainterm) surface expression, which appeared in liquid cultures supplemented with stem cell factor?+?interleukin 3?+?erythropoietin at days 7-10. However, neither immature (day 4) glycophorin Adim erythroid cells nor mature (day 14) glycophorin Abright erythroblasts were sensitive to TRAIL-mediated apoptosis. Moreover, pre-exposure to TRAIL significantly decreased the number and size of erythroid colonies in semisolid assays. These adverse effects of TRAIL were selective for erythropoiesis, as TRAIL did not significantly influence the survival of cells differentiating along the megakaryocytic, granulocytic, or monocytic lineages. Furthermore, TRAIL was detected by Western blot analysis in lysates obtained from normal bone marrow mononuclear cells. These findings indicate that TRAIL acts in a lineage- and stage of differentiation-specific manner, as a negative regulator of normal erythropoiesis.