24S-hydroxycholesterol in cerebrospinal fluid is elevated in early stages of dementia

The brain is the most cholesterol-rich organ in the human body. Accumulation of excess cholesterol in hippocampal neurons promotes the cleavage of the amyloid precursor protein (APP) into amyloidogenic components with the consequence of the acceleration of neuronal degeneration. Conversion of cholesterol to 24S-hydroxycholesterol mediated by cholesterol 24S-hydroxylase (CYP46) is the major pathway for the elimination of brain cholesterol and the maintenance of brain cholesterol homeostasis. We examined whether cerebrospinal fluid (CSF) 24S-hydroxycholesterol levels differ between patients with dementia, patients with mild cognitive impairment (MCI), and cognitively intact control subjects. Plasma and CSF concentrations of 24S-hydroxycholesterol and cholesterol in 32 patients with Alzheimer's disease (AD), 11 patients with vascular dementia, seven patients with MCI, and seven cognitively intact control subjects were measured by combined gas-chromatography/mass spectrometry. We show elevated concentrations of 24S-hydroxycholesterol in the CSF of AD patients and we interpret this finding as a consequence of increased cholesterol turnover in the central nervous system during neurodegeneration. The observed influence of the apolipoprotein E epsilon4 (APOE4) allele on CSF 24S-hydroxycholesterol concentrations with a gene-dosage effect suggests the existence of a link between the AD risk factor APOE4 and CNS cholesterol metabolism. The elevation of CSF 24S-hydroxycholesterol appears to occur early in the disease process, since patients with mild cognitive impairment had also increased CSF concentrations of this compound. We believe that the CSF concentration of 24S-hydroxycholesterol is altered in AD-related neurodegeneration and thus, CSF 24S-hydroxycholesterol may be a marker for monitoring the onset and progression of the disease.

Enzymatic production of biodiesel from cotton seed oil using t-butanol as a solvent

The enzymatic production of biodiesel by methanolysis of cottonseed oil was studied using immobilized Candida antarctica lipase as catalyst in t-butanol solvent. Methyl ester production and triacylglycerol disappearance were followed by HPLC chromatography. It was found, using a batch system, that enzyme inhibition caused by undissolved methanol was eliminated by adding t-butanol to the reaction medium, which also gave a noticeable increase of reaction rate and ester yield. The effect of t-butanol, methanol concentration and temperature on this system was determined. A methanolysis yield of 97% was observed after 24h at 50 degrees C with a reaction mixture containing 32.5% t-butanol, 13.5% methanol, 54% oil and 0.017 g enzyme (g oil)(-1). With the same mixture, a 95% ester yield was obtained using a one step fixed bed continuous reactor with a flow rate of 9.6 mlh(-1) (g enzyme)(-1). Experiments with the continuous reactor over 500 h did not show any appreciable decrease in ester yields.

Plasma 24S-hydroxycholesterol: a peripheral indicator of neuronal degeneration and potential state marker for Alzheimer's disease

The conversion of brain cholesterol into 24S-hydroxycholesterol and its subsequent release into the periphery is probably an important step for the maintenance of brain cholesterol homeostasis. Recent findings suggest that plasma 24S-hydroxycholesterol may be elevated in Alzheimer's disease (AD) and vascular dementia at least at some stage of the disease, suggesting increased brain cholesterol turnover during neurodegeneration. We investigated whether plasma 24S-hydroxycholesterol concentrations depend on the severity of AD and on the apolipoprotein E (apoE) genotype. Severity of AD and inheritance of the apoE4 allele were independently associated with reduced plasma 24S-hydroxycholesterol/cholesterol ratios. The results suggest that the decrease of plasma 24S-hydroxycholesterol/cholesterol in severely affected AD patients is a peripheral marker for loss of cholesterol 24S-hydroxylase in the CNS. Inheritance of the apoE4 allele may be associated with increased apoE-mediated transport of brain cholesterol to the periphery or with decreased activity of the 24S-hydroxylase. Longitudinal studies will assess the validity of the ratio plasma 24S-hydroxycholesterol/cholesterol as a state marker for AD.

DOT1L-mediated H3K79me2 modification critically regulates gene expression during cardiomyocyte differentiation

Epigenetic changes on DNA and chromatin are implicated in cell differentiation and organogenesis. For the heart, distinct histone methylation profiles were recently linked to stage-specific gene expression programs during cardiac differentiation in vitro. However, the enzymes catalyzing these modifications and the genes regulated by them remain poorly defined. We therefore decided to identify the epigenetic enzymes that are potentially involved in cardiomyogenesis by analyzing the expression profile of the 85 genes encoding the epigenetic-related proteins in mouse cardiomyocytes (CMs), and then study how they affect gene expression during differentiation and maturation of this cell type. We show here with gene expression screening of epigenetic enzymes that the highly expressed H3 methyltransferase disruptor of telomeric silencing 1-like (DOT1L) drives a transitional pattern of di-methylation on H3 lysine 79 (H3K79) in CMs at different stages of differentiation in vitro and in vivo. Through a genome-wide chromatin-immunoprecipitation DNA-sequencing approach, we found H3K79me2 enriched at genes expressed during cardiac differentiation. Moreover, knockdown of Dot1L affected the expression of H3K79me2-enriched genes. Our results demonstrate that histone methylation, and in particular DOT1L-mediated H3K79me2 modification, drives cardiomyogenesis through the definition of a specific transcriptional landscape.

BIM upregulation and ROS-dependent necroptosis mediate the antitumor effects of the HDACi Givinostat and Sorafenib in Hodgkin lymphoma cell line xenografts

Relapsed/refractory Hodgkin's lymphoma (HL) is an unmet medical need requiring new therapeutic options. Interactions between the histone deacetylase inhibitor Givinostat and the RAF/MEK/ERK inhibitor Sorafenib were examined in HDLM-2 and L-540 HL cell lines. Exposure to Givinostat/Sorafenib induced a synergistic inhibition of cell growth (range, 70-80%) and a marked increase in cell death (up to 96%) due to increased H3 and H4 acetylation and strong mitochondrial injury. Gene expression profiling indicated that the synergistic effects of Givinostat/Sorafenib treatment are associated with the modulation of cell cycle and cell death pathways. Exposure to Givinostat/Sorafenib resulted in sustained production of reactive oxygen species (ROS) and activation of necroptotic cell death. The necroptosis inhibitor Necrostatin-1 prevented Givinostat/Sorafenib-induced ROS production, mitochondrial injury, activation of BH3-only protein BIM and cell death. Knockdown experiments identified BIM as a key signaling molecule that mediates Givinostat/Sorafenib-induced oxidative death of HL cells. Furthermore, in vivo xenograft studies demonstrated a 50% reduction in tumor burden (P<0.0001), a 5- to 15-fold increase in BIM expression (P < 0.0001) and a fourfold increase in tumor necrosis in Givinostat/Sorafenib-treated animals compared with mice that received single agents. These results provide a rationale for exploring Givinostat/Sorafenib combination in relapsed/refractory HL.

FGF Trapping Inhibits Multiple Myeloma Growth through c-Myc Degradation-Induced Mitochondrial Oxidative Stress

Multiple myeloma, the second most common hematologic malignancy, frequently relapses because of chemotherapeutic resistance. Fibroblast growth factors (FGF) act as proangiogenic and mitogenic cytokines in multiple myeloma. Here, we demonstrate that the autocrine FGF/FGFR axis is essential for multiple myeloma cell survival and progression by protecting multiple myeloma cells from oxidative stress-induced apoptosis. In keeping with the hypothesis that the intracellular redox status can be a target for cancer therapy, FGF/FGFR blockade by FGF trapping or tyrosine kinase inhibitor impaired the growth and dissemination of multiple myeloma cells by inducing mitochondrial oxidative stress, DNA damage, and apoptotic cell death that were prevented by the antioxidant vitamin E or mitochondrial catalase overexpression. In addition, mitochondrial oxidative stress occurred as a consequence of proteasomal degradation of the c-Myc oncoprotein that led to glutathione depletion. Accordingly, expression of a proteasome-nondegradable c-Myc protein mutant was sufficient to avoid glutathione depletion and rescue the proapoptotic effects due to FGF blockade. These findings were confirmed on bortezomib-resistant multiple myeloma cells as well as on bone marrow-derived primary multiple myeloma cells from newly diagnosed and relapsed/refractory patients, including plasma cells bearing the t(4;14) translocation obtained from patients with high-risk multiple myeloma. Altogether, these findings dissect the mechanism by which the FGF/FGFR system plays a nonredundant role in multiple myeloma cell survival and disease progression, and indicate that FGF targeting may represent a therapeutic approach for patients with multiple myeloma with poor prognosis and advanced disease stage. SIGNIFICANCE: This study provides new insights into the mechanisms by which FGF antagonists promote multiple myeloma cell death. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/11/2340/F1.large.jpg.

Estrogen receptor β ligation inhibits Hodgkin lymphoma growth by inducing autophagy

Although Hodgkin lymphoma (HL) is curable with current therapy, at least 20% of patients relapse or fail to make complete remission. In addition, patients who achieve long-term disease-free survival frequently undergo infertility, secondary malignancies, and cardiac failure, which are related to chemotherapeutic agents and radiation therapies. Hence, new therapeutic strategies able to counteract the HL disease in this important patient population are still a matter of study. Estrogens, in particular 17β-estradiol (E2), have been suggested to play a role in lymphoma cell homeostasis by estrogen receptors (ER) β activation. On these bases, we investigated whether the ligation of ERβ by a selective agonist, the 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), could impact HL tumor growth. We found that DPN-mediated ERβ activation led to a reduction of in vitro cell proliferation and cell cycle progression by inducing autophagy. In nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice engrafted with HL cells, ERβ activation by DPN was able to reduce lymphoma growth up to 60% and this associated with the induction of tumor cell autophagy. Molecular characterization of ERβ-induced autophagy revealed an overexpression of damage-regulated autophagy modulator 2 (DRAM2) molecule, whose role in autophagy modulation is still debated. After ERβ activation, both DRAM2 and protein 1 light chain 3 (LC3), a key actor in the autophagosome formation, strictly interacted each other and localized at mitochondrial level.

Altogether these results suggest that targeting ERβ with selective agonists might affect HL cell proliferation and tumor growth via a mechanism that brings into play DRAM2-dependent autophagic cascade.

Phase II study of sorafenib in patients with relapsed or refractory lymphoma

The safety and activity of the multikinase inhibitor sorafenib were investigated in patients with relapsed or refractory lymphoproliferative disorders who received sorafenib (400 mg) twice daily until disease progression or appearance of significant clinical toxicity. The primary endpoint was overall response rate (ORR). Biomarkers of sorafenib activity were analysed at baseline and during treatment. Thirty patients (median age, 61 years; range, 18-74) received a median of 4 months of therapy. Grade 3-4 toxicities included hand/foot skin reactions (20%), infections (12%), neutropenia (20%) and thrombocytopenia (14%). Two patients achieved complete remission (CR), and two achieved partial remission (PR) for an ORR of 13%. Stable disease (SD) and progressive disease (PD) was observed in 15 (50%) and 11 patients (37%), respectively. The median overall survival (OS) for all patients was 16 months. For patients who achieved CR, PR and SD, the median time to progression and OS was 5 and 24 months, respectively. Compared with patients with PD, responsive patients had significantly higher baseline levels of extracellular signal-regulated kinase phosphorylation and autophagy and presented a significant reduction of these parameters after 1 month of therapy. Sorafenib was well tolerated and had a clinical activity that warrants development of combination regimens.

Constitutive localization of DR4 in lipid rafts is mandatory for TRAIL-induced apoptosis in B-cell hematologic malignancies

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) acts as an apoptosis inducer for cancer cells sparing non-tumor cell targets. However, several phase I/II clinical trials have shown limited benefits of this molecule. In the present work, we investigated whether cell susceptibility to TRAIL ligation could be due to the presence of TRAIL death receptors (DRs) 4 and 5 in membrane microdomains called lipid rafts. We performed a series of analyses, either by biochemical methods or fluorescence resonance energy transfer (FRET) technique, on normal cells (i.e. lymphocytes, fibroblasts, endothelial cells), on a panel of human cancer B-cell lines as well as on CD19⁺ lymphocytes from patients with B-chronic lymphocytic leukemia, treated with different TRAIL ligands, that is, recombinant soluble TRAIL, specific agonistic antibodies to DR4 and DR5, or CD34⁺ TRAIL-armed cells. Irrespective to the expression levels of DRs, a molecular interaction between ganglioside GM3, abundant in lymphoid cells, and DR4 was detected. This association was negligible in all non-transformed cells and was strictly related to TRAIL susceptibility of cancer cells. Interestingly, lipid raft disruptor methyl-beta-cyclodextrin abrogated this susceptibility, whereas the chemotherapic drug perifosine, which induced the recruitment of TRAIL into lipid microdomains, improved TRAIL-induced apoptosis. Accordingly, in ex vivo samples from patients with B-chronic lymphocytic leukemia, the constitutive embedding of DR4 in lipid microdomains was associated per se with cell death susceptibility, whereas its exclusion was associated with TRAIL resistance. These results provide a key mechanism for TRAIL sensitivity in B-cell malignances: the association, within lipid microdomains, of DR4 but not DR5, with a specific ganglioside, that is the monosialoganglioside GM3. On these bases we suggest that lipid microdomains could exert a catalytic role for DR4-mediated cell death and that an ex vivo quantitative FRET analysis could be predictive of cancer cell sensitivity to TRAIL.

YM155 sensitizes triple-negative breast cancer to membrane-bound TRAIL through p38 MAPK- and CHOP-mediated DR5 upregulation

Because available treatments have limited efficacy in triple-negative breast cancer (TNBC), the identification of new therapeutic strategies to improve patients' outcome is urgently needed. In our study, we investigated the effects of the administration of the small molecule selective survivin suppressant YM155, alone or in association with CD34+ cells transduced with a replication-deficient adenovirus encoding the human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene (CD34-TRAIL+ cells), in three TNBC cell models. YM155 exposure significantly impaired TNBC cell growth and selectively modulated survivin expression at both mRNA and protein level. In addition, co-culturing YM155-treated TNBC cells with CD34-TRAIL+ cells resulted in markedly increased cytotoxic effect and apoptotic response in comparison with single treatments. Such a chemosensitizing effect was observed only in TNBC cells inherently expressing DR5 and relied on the ability of YM155 to upregulate DR5 expression through a p38 MAPK- and CHOP-dependent mechanism. YM155/CD34-TRAIL+ combination also showed a significant inhibitory effect on the growth of DR5-expressing TNBC cells following xenotransplantation into NOD/SCID mice, in the absence of toxicity. Overall, our data (i) provide, for the first time, evidence that YM155 sensitizes TNBC cells to CD34-TRAIL+ cells-induced apoptosis by a mechanism involving the downregulation of survivin and the simultaneous p38 MAPK- and CHOP-mediated upregulation of DR5, and (ii) suggest the combination of YM155 with TRAIL-armed CD34+ progenitor cells as a promising therapeutic option for patients with TNBC expressing DR5.

Phase II study of perifosine and sorafenib dual-targeted therapy in patients with relapsed or refractory lymphoproliferative diseases

PURPOSE

To evaluate safety and activity of perifosine and sorafenib combination therapy in patients with lymphoproliferative diseases.

EXPERIMENTAL DESIGN

Patients with relapsed and refractory lymphoproliferative diseases received perifosine (50 mg twice daily) for 1 month. Patients achieving less than partial response (PR) after perifosine alone were administered the combination therapy [perifosine plus sorafenib (400 mg twice daily)] until progressive disease (PD) or unacceptable toxicity occurred. The pERK and pAKT in peripheral blood lymphocytes as well as serum cytokine levels were investigated as predictive biomarkers of response.

RESULTS

Forty patients enrolled in this study. After 1 month of perifosine alone, 36 who achieved less than PR went on to combination therapy, whereas four patients with chronic lymphocytic leukemia (CLL) who achieved PR continued with perifosine alone for a median of 10 months (range, 4-21). The most common drug-related toxicities were grade 1-2 anemia (17%), thrombocytopenia (9%), diarrhea (25%), joint pain (22%), and hand-foot skin reaction (25%). Three patients experienced grade 3 pneumonitis. Eight patients (22%) achieved PR, 15 (42%) achieved stable disease, and 13 (36%) experienced PD. A 28% PR rate was recorded for 25 patients with Hodgkin lymphoma. Among all patients, median overall survival and progression-free survival were 16 and 5 months, respectively. Early reductions in pERK and pAKT significantly correlated with the probability of clinical response.

CONCLUSIONS

Perifosine and sorafenib combination therapy is feasible with manageable toxicity and demonstrates promising activity in patients with Hodgkin lymphoma. The predictive value of pERK and pAKT should be confirmed in a larger patient cohort.

The maize WD-repeat gene ZmRbAp1 encodes a member of the MSI/RbAp sub-family and is differentially expressed during endosperm development

Members of the MSI/RbAp sub-family of WD-repeat proteins are widespread in eukaryotic organisms and form part of multiprotein complexes that are involved in various biological pathways, including chromatin assembly, regulation of gene transcription, and cell division. In this study we report the isolation and characterization of a cDNA sequence from Zea mays, which encodes an RbAp-like protein (ZmRbAp1) that binds acetylated histones H3 and H4 and suppresses mutations that have a negative effect on the Ras/cAMP pathway in yeast. The ZmRbAp genes form a gene family and are expressed in different tissues of Z. mays L. plants. Determination of its expression pattern during maize seed development revealed that ZmRbAp transcripts are abundant during the initial stages of endosperm formation. In addition, the transcripts are specifically localized in shoot apical meristem and leaf primordia of the embryo. A possible role for the ZmRbAp genes in early endosperm differentiation and plant development is discussed.

Myeloablative doses of yttrium-90-ibritumomab tiuxetan and the risk of secondary myelodysplasia/acute myelogenous leukemia

BACKGROUND

Because the long-term toxicity of myeloablative radioimmunotherapy remains a matter of concern, the authors evaluated the hematopoietic damage and incidence of secondary myelodysplastic syndrome and acute myelogenous leukemia (sMDS/AML) in patients who received myeloablative doses of the radiolabeled antibody yttrium-90 (⁹⁰Y)-ibritumomab tiuxetan.

METHODS

The occurrence of sMDS/AML was investigated prospectively in 53 elderly patients with non-Hodgkin lymphoma (NHL) who underwent an autograft after high-dose radioimmunotherapy (HD-RIT) myeloablative conditioning with ⁹⁰Y-ibritumomab tiuxetan. Bone marrow (BM) hematopoietic progenitors and telomere length (TL) also were investigated.

RESULTS

At a median follow-up of 49 months, 4 patients developed sMDS/AML at 6 months, 12 months, 27 months, and 36 months after HD-RIT, and the 5-year cumulative incidence of sMDS/AML was 8.29%. A significant but transient decrease in BM granulocyte-macrophage progenitors was observed; whereas multilineage, erythroid, and fibroblast progenitors were unaffected. A significant and persistent shortening of BM TL also was detected. A matched-pair analysis comparing the study patients with 55 NHL patients who underwent autografts after chemotherapy-based myeloablative conditioning demonstrated a 8.05% 5-year cumulative incidence of sMDS/AML.

CONCLUSIONS

HD-RIT for patients with NHL was associated with 1) limited toxicity on hematopoietic progenitors, 2) accelerated TL shortening, and 3) non-negligible incidence of sMDS/AML, which nevertheless was comparable to the incidence observed in a matched group of patients who received chemotherapy-based conditioning. Thus, in the current series of elderly patients with NHL, the development of sMDS/AML was not influenced substantially by HD-RIT.

Autophagy as a pathogenic mechanism and drug target in lymphoproliferative disorders

Autophagy represents a key mechanism of cytoprotection that can be activated by a variety of extracellular and intracellular stresses and allows the cell to sequester cytoplasmic components and damaged organelles, delivering them to lysosomes for degradation and recycling. However, the autophagy process has also been associated with the death of the cell. It has been demonstrated to be constitutive in some instances and inducible in others, and the idea that it could represent a pathogenetic determinant as well as a possible prognostic tool and a therapeutic target in a plethora of human diseases has recently been considered. Among these, cancer represents a major one. In this review, we recapitulate the critical implications of autophagy in the pathogenesis, progression, and treatment of lymphoproliferative disorders. Leukemias and lymphomas, in fact, represent paradigmatic human diseases in which advances have recently been made in this respect.

A First-in-human Study of Tenalisib (RP6530), a Dual PI3K δ/γ Inhibitor, in Patients With Relapsed/Refractory Hematologic Malignancies: Results From the European Study

BACKGROUND

Tenalisib (RP6530) is a novel, highly specific, dual phosphoinositide-3 kinases (PI3K) δ/γ inhibitor with nano-molar potency.

MATERIAL AND METHODS

This was a phase I, open-label, 3 + 3 dose escalation, maximum tolerated dose determination study to evaluate the safety, pharmacokinetics, and efficacy of tenalisib in patients with relapsed/refractory hematologic malignancies. Tenalisib was administered orally twice/thrice daily in 28-day cycles with starting dose of 25 mg twice daily.

RESULTS

Thirty-five patients were enrolled across 11 dose levels. No dose limiting toxicity was reported at any of the dose levels. The most common treatment-emergent adverse events irrespective of causality were asthenia and cough in 15 (43%) patients and pyrexia in 13 (37%) patients. The most frequently reported related treatment-emergent adverse events were diarrhea, nausea, and vomiting. Related grade 3/4 adverse events were limited to events of hypertriglyceridemia, neutropenia, and diarrhea. Pharmacokinetics showed rapid absorption. Based on maximum plasma concentration and area under the plasma-concentration time curve, dose proportionality was observed up to 400 mg dose. Of 31 patients included in the efficacy analysis, complete response was seen in 2 (7%) patients and partial response in 4 (13%) patients, with an overall response rate of 19% and a disease-control rate of 61%. The median duration of response was 5.7 months. Responders demonstrated a marked downregulation of phospho-AKT on C1D8.

CONCLUSION

Tenalisib demonstrated acceptable safety up to 1200 mg twice a day with no dose-limiting toxicities. Consistent clinical response was seen at doses 200 mg BID and above. Pharmacodynamics correlated well with clinical outcome. Further phase I/II studies are being undertaken to evaluate efficacy across different histologies.

Cholesterol dynamics in the foetal and neonatal brain as reflected by circulatory levels of 24S-hydroxycholesterol

Oxysterols, particularly those hydroxylated in the steroid side-chain, are formed from cholesterol by specific cytochrome P450 enzymes and may facilitate elimination of cholesterol from extrahepatic sources. In humans, the greatest portion of circulating 24S-hydroxycholesterol (24S-OH-Chol) is derived from the brain and the absolute concentration depends on age. In the present study, concentrations of 24S-OH-Chol and for comparison 27-OH-Chol were determined by a highly sensitive isotope dilution method using gas chromatography-mass spectrometry in serum samples from normal preterm and term neonates and those with Rhesus haemolytic disease, taken serially for diagnostic purposes. Serum concentrations of cholesterol, 24S-OH-Chol and 27-OH-Chol were similar in venous versus arterial cord blood of 6 term neonates. Serum concentrations of 24S-OH-Chol and 27-OH-Chol in 12 small for gestational age (SGA) preterm neonates were significantly lower than those in 12 appropriate for gestational age (AGA) preterm neonates (p < 0.001), and also lower than those in 12 SGA (0 < 0.001) and 12 AGA term neonates (p < 0.05). Serum cholesterol was significantly higher in preterm than in term neonates (p < 0.001). 24S-OH-Chol serially determined in 8 infants with Rhesus haemolytic disease increased 5-6-fold during the first 3 mo after birth (from 42 +/- 20 ng ml(-1) to 227 +/- 71 ng ml(-1)). 27-OH-Chol increased simultaneously from 30 +/- 14 ng ml(-1) to 100 +/- 39 ng ml(-1).

CONCLUSION

Serum concentrations of 24S-OH-Chol increased 5-6-fold after birth. This could be an indication of normal cholesterol metabolism in the developing neonatal brain.

Use of RNAlater as a preservation method for parasitic coprology studies in wild-living chimpanzees

We evaluated the use of an RNA stabilisation buffer, RNAlater (Ambion, Austin, Texas), as a preservation medium for parasitic coprology analysis of faecal samples collected from chimpanzees living in the wild (Pan troglodytes troglodytes). Thirty faecal samples collected in the forests of south-east Cameroon (Mambele area) from 2003 to 2011 were preserved in RNAlater at -80 °C and analysed for their parasite content. We identified and counted parasitic elements and assessed their shape, size and morphology in relation to the storage time of the samples. We found that parasite elements were identifiable in RNAlater preserved samples after as many as 7 years, showing that RNAlater could be an effective and reliable preservation medium for coprology. Thus, its use could be an interesting way to optimise sample collection for several types of studies (parasitology and bacteriology/virology) at once, especially considering the logistically challenging and time-consuming field campaigns needed to obtain these faecal samples.

MicroRNA-127-3p controls murine hematopoietic stem cell maintenance by limiting differentiation

The balance between self-renewal and differentiation is crucial to ensure the homeostasis of the hematopoietic system, and is a hallmark of hematopoietic stem cells. However, the underlying molecular pathways, including the role of micro-RNA, are not completely understood. To assess the contribution of micro-RNA, we performed micro-RNA profiling of hematopoietic stem cells and their immediate downstream progeny multi-potent progenitors from wild-type control and Pbx1-conditional knockout mice, whose stem cells display a profound self-renewal defect. Unsupervised hierarchical cluster analysis separated stem cells from multi-potent progenitors, suggesting that micro-RNA might regulate the first transition step in the adult hematopoietic development. Notably, Pbx1-deficient and wild-type cells clustered separately, linking micro-RNAs to self-renewal impairment. Differential expression analysis of micro-RNA in the physiological stem cell-to-multi-potent progenitor transition and in Pbx1-deficient stem cells compared to control stem cells revealed miR-127-3p as the most differentially expressed. Furthermore, miR-127-3p was strongly stem cell-specific, being quickly down-regulated upon differentiation and not re-expressed further downstream in the bone marrow hematopoietic hierarchy. Inhibition of miR-127-3p function in Lineage-negative cells, achieved through a lentiviral-sponge vector, led to severe stem cell depletion, as assessed with serial transplantation assays. miR-127-3p-sponged stem cells displayed accelerated differentiation, which was uncoupled from proliferation, accounting for the observed stem cell reduction. miR-127-3p overexpression in Lineage-negative cells did not alter stem cell pool size, but gave rise to lymphopenia, likely due to lack of miR-127-3p physiological downregulation beyond the stem cell stage. Thus, tight regulation of miR-127-3p is crucial to preserve the self-renewing stem cell pool and homeostasis of the hematopoietic system.

Induction of death receptor 5 expression in tumor vasculature by perifosine restores the vascular disruption activity of TRAIL-expressing CD34(+) cells

The proapoptotic death receptor 5 (DR5) expressed by tumor associated endothelial cells (TECs) mediates vascular disrupting effects of human CD34(+) cells engineered to express membrane-bound tumor necrosis factor-related apoptosis-inducing ligand (CD34-TRAIL (+) cells) in mice. Indeed, lack of DR5 on TECs causes resistance to CD34-TRAIL (+) cells. By xenografting in nonobese diabetic/severe combined immunodeficient mice the TRAIL-resistant lymphoma cell line SU-DHL-4V, which generates tumors lacking endothelial DR5 expression, here we demonstrate for the first time that the Akt inhibitor perifosine induces in vivo DR5 expression on TECs, thereby overcoming tumor resistance to the vascular disruption activity of CD34-TRAIL (+) cells. In fact, CD34-TRAIL (+) cells combined with perifosine, but not CD34-TRAIL (+) cells alone, exerted marked antivascular effects and caused a threefold increase of hemorrhagic necrosis in SU-DHL-4V tumors. Consistent with lack of DR5 expression, CD34-TRAIL (+) cells failed to affect the growth of SU-DHL-4V tumors, but CD34-TRAIL (+) cells plus perifosine reduced tumor volumes by 60 % compared with controls. In view of future clinical studies using membrane-bound TRAIL, our results highlight a strategy to rescue patients with primary or acquired resistance due to the lack of DR5 expression in tumor vasculature.

Tubero-infundibular dopaminergic function in cirrhotic patients: evaluation by nomifensine and domperidone

Cirrhotic patients reportedly show alterations of anterior pituitary hormone secretion, which may reflect an underlying defective central neurotransmitter function. In this study, we have investigated the catecholaminergic control of prolactin (Prl) and growth hormone (GH) secretion in cirrhotic patients by means of an indirectly acting dopamine (DA) and norepinephrine agonist, nomifensine (Nom), and a DA receptor antagonist, domperidone (Dom). Basal GH levels were higher in the 12 female and male cirrhotic patients than in the 12 age- and sex-matched normal controls, while no difference was present in basal Prl values. Administration of Nom (200 mg po) suppressed basal Prl levels (at least 30% inhibition at three consecutive times post-drug administration) in 6/12 controls and in 6/12 cirrhotic patients, the frequency of negative responses not being different between the two groups. Nom induced a slight elevation of GH levels in controls, and evoked a more marked and sustained GH increase in cirrhotic patients. Administration of Dom (4 mg iv) induced similar Prl increments in 6 male controls and 6 male cirrhotic patients. Normal Prl responsiveness to Nom and Dom points to the existence of preserved tubero-infundibular DA function and modulation of pituitary DA receptors in the cirrhotic patients investigated. Higher GH responsiveness to Nom is compatible with a different bioavailability of the drug.

Abstract 2420: The dual PI3K δ/γ inhibitor RP6530 in combination with Brentuximab Vedotin (SGN-35) synergistically induces cell death via inhibition of tubulin polymerization in Hodgkin lymphoma cell lines

Introduction: The phosphatidylinositol 3-kinase (PI3K) pathway is consistently activated in relapsed/refractory Hodgkin lymphoma (HL). Expression of the δ and γ isoforms of PI3K is restricted to cells of the hematopoietic system, suggesting that RP6530, a novel dual PI3K δ/γ Inhibitor, might represent a promising approach in the treatment of lymphomas. The CD30-directed antibody-drug conjugate, Brentuximab Vedotin (BV), has recently been reported to induce a high overall response rate in relapsed/refractory HL, but is associated with limited response duration. Combination therapies aimed at enhancing the anti-tumor activity of BV and eventually reducing its side effects may have significant clinical impact in the treatment of relapsed/refractory HL. Our study aimed at investigating the activity and mechanism(s) of action of RP6530 in combination with BV in preclinical HL models.

Methods and Results: RP6530 was active against a panel of HL cell lines (L-540, KM-H2, L-428). Using a WST assay, increasing concentrations of RP6530 (1.25 - 20 μM) resulted in a dose-dependent inhibition of cell growth (range, 20% to 40%). BV, at clinically achievable concentrations induced a significant growth inhibition (range, 30% to 40%) in all HL cells. Remarkably, when RP6530 was combined with BV at minimal, or mildly inhibitory concentrations, a highly synergistic inhibition in all HL cells was observed. Following a 48 hour exposure, RP6530 (5 μM) and BV (10 ng/ml) synergistically inhibited the mean (±SEM) growth of HL cells (RP6530: 9 ± 3%; BV: 12 ± 3%; RP6530/BV: 26 ± 3%). While single agents induced only 20% HL cell death, combination of RP6530 and BV caused remarkable induction of apoptosis (90%), with Combination Index (CI) as low as 0.003. To assess potential effects of RP6530/BV on microtubule dynamics, we conducted a tubulin polymerization assay. Highly purified α/β-tubulin and GTP were incubated with RP6530 and/or BV. While single agent activity of RP6530 or BV was modest, RP6530/BV significantly inhibited tubulin polymerization in a time-dependent manner (P &lt; 0.0001), suggesting that RP6530/BV disrupts microtubules in cells by abrogating microtubule assembly. Finally, in vivo experiments were conducted to investigate the antitumor activity of the two drugs. Compared to mock controls, treatment of NOD/SCID mice bearing KM-H2 tumor nodules with RP6530 (150 mg/kg/BID/3 weeks) or BV (0.5 mg/kg/q4×4d) resulted in a mean tumor growth inhibition of 90% and 40%, respectively. No mice experienced any apparent treatment-related toxicity. Effect of RP6530/BV in the xenograft model is currently being evaluated and results will be presented.

Conclusions: The combination of RP6530 and BV exerts a marked in vitro synergistic antitumor activity against HL cells, thereby representing a promising therapeutic strategy in the treatment of relapsed/refractory HL.

Citation Format: Silvia L. Locatelli, Giuseppa Careddu, Srikant Viswanadha, Swaroop Vakkalanka, Luca Castagna, Armando Santoro, Carmelo Carlo-Stella. The dual PI3K δ/γ inhibitor RP6530 in combination with Brentuximab Vedotin (SGN-35) synergistically induces cell death via inhibition of tubulin polymerization in Hodgkin lymphoma cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2420. doi:10.1158/1538-7445.AM2015-2420