Deaminase Gene Research Articles

Growth inhibition of human breast cancer cells and down-regulation of ODC1 and ADA genes by Nepeta binaloudensis

Nepeta binaloudensis Jamzad, Lamiaceae, is a rare medicinal plant endemic to Iran. In spite of many studies about the chemical constituents and antibacterial effects of this species, no report has been provided about its cytotoxic and anticancer activities. In this study we have evaluated the effects of EtOH 70%, hexane and aqueous extracts of N. binaloudensis on the cell proliferation and n-hexane extract on the expression of adenosine deaminase and ornithine decarboxylase 1 genes in breast cancer cell lines (MCF-7, MDA-MB-231) compared to non-cancer line (MCF-10A). The cell lines were subjected to increasing doses of the extracts ranging from 10 to 320μg/ml. Cell viability was quantified by MTS assay. Expression of adenosine deaminase and ornithine decarboxylase 1 genes was analyzed by real time PCR. N. binaloudensis inhibited the growth of malignant cells in a time and dose-dependent manner. Among extracts of N. binaloudensis, the hexane extract was found to be more toxic compared to other extracts. Results showed a marked decrease in the expression of ornithine decarboxylase 1 and adenosine deaminase genes in cancer cell lines. At 60μg/ml concentration of N. binaloudensis hexane extract ornithine decarboxylase 1 and adenosine deaminase mRNA expression were reduced 4.9 fold and 3.5 fold in MCF-7 cell line and 3.6 fold and 2.6 fold in MDA-MB-231 cell line compared to control, respectively. The result of our study highlights the potential influences of N. binaloudensis hexane extract on ornithine decarboxylase 1 and adenosine deaminase genes expression in breast cancer cells and its relation to inhibition of cancer cell growth.

ASCIA‐P69: A NOVEL AICDA MUTATION IN A CASE OF AUTOSOMAL RECESSIVE HYPER‐IGM SYNDROME, GROWTH HORMONE DEFICIENCY AND AUTOIMMUNITY

The Hyper-immunoglobulin M syndromes (HIGM) or immunoglobulin class switch recombination (Ig-CSR) deficiencies are rare primary immunodeficiency (PID) disorders. A 9-year-old girl with recurrent ear infections and failure to thrive since the age of 6 months had normal lymphocyte subsets, but extremely elevated IgM and significantly decreased IgG and IgA. In view of the patient's short stature, growth hormone evaluation was carried out and growth hormone deficiency established. The patient underwent Ig replacement therapy and received short course of growth hormone therapy and responded well. Furthermore, the patient developed benign cervical lymphadenopathy, as well as elevated ESR, positive autoantibodies to SSA-Ro, and severely dry eyes, which partially responded to both the punctate occlusion and systemic corticosteroids, at the age of 7 years. Sequencing analysis of the exons from activation-induced cytidine deaminase ( AICDA ) gene revealed that the patient was homozygous for a single T to C transversion at position 455 in exon 4, which replaces a Valine with an Alanine. To our knowledge, this is a new AICDA mutation, which has not been reported previously in HIGM. Autoimmune complications have been formerly described in the reported series of AICDA deficient HIGM; however the association with growth hormone deficiency is rarely reported.

The war against cancer: Suicide gene therapy

<p>The National Cancer Institute and the American Cancer Society announced that 1.6 million new cancer cases are projected to occur in the USA in 2016. One of the most innovative approaches against cancer is suicide gene therapy, in which suicide-inducing transgenes are introduced into cancer cells. When cancer treatments target the total elimination of tumor cells, there will be no side effects for normal cells. Cancer tissues are targeted through various targeted transport methods, followed by tissue-specific enzymes converting a systemically suitable prodrug into an active drug in the tumor. Suicidal genes are delivered by transporters, such as viral and non-viral vectors, into cancer cells. Suicide gene therapeutic strategies currently pursued are herpes simplex virus thymidine kinase gene with prodrug ganciclovir, cytosine deaminase gene, carboxyl esterase/irinotecan, varicella zoster virus thymidine kinase/6-methoxypurine arabinonucleoside, nitroreductase Nfsb/5-(aziridin-1-yl)-2,4-dinitrobenzamide, carboxypeptidase G2/4-[(2-chloroethyl)(2- mesyloxyethyl)amino]benzoyl-L-glutamic acid, cytochrome p450-isofosfamide, and cytochrome p450-cyclophosphamide. The goal of this review is to summarize the different suicide gene systems and gene delivery vectors addressed to cancer cells, with a particular emphasis on recently developed systems. Finally, we briefly describe the advantageous clinical applications and potential side effects of suicide gene therapy. </p>

Role of the N-acetylglucosamine kinase (Hxk1) in the regulation of white-gray-opaque tristable phenotypic transitions in C. albicans

The amino sugar N-acetylglucosamine (GlcNAc) is a host-related environmental cue and a potent inducer of morphological transitions in the human fungal pathogen Candida albicans. It has been well established that GlcNAc promotes white-to-opaque switching and yeast-to-hyphal growth transition primarily through the Ras-cAMP signaling pathway. As a commensal yeast of humans, C. albicans can efficiently use GlcNAc as the carbon source. In this study, we sought to investigate whether the catabolic pathway of GlcNAc is involved in the regulation of white-gray-opaque tristable transitions in C. albicans. Phenotypic switching assays demonstrated that deletion of the GlcNAc kinase gene, HXK1, induced the gray and opaque phenotypes in a SC5314 background strain, which is heterozygous at the mating type locus (a/α) and is unable to switch to the gray or opaque phenotype under standard culture conditions. Cell type-enriched genes were exclusively expressed in the white, gray, and opaque cells of the hxk1/hxk1 mutant. Mating assays demonstrated that, similar to the counterparts of BJ1097 (a natural white-gray-opaque switchable strain), opaque cells of the hxk1/hxk1 mutant (Δ/α) mated more efficiently than white and gray cells. The transcription factors, Wor1 and Efg1, are required for the development of the opaque and white cell types in the hxk1/hxk1 mutant, respectively. However, deletion of the GlcNAc-specific transporter gene (NGT1), GlcNAc-6-phosphate deacetylase gene (DAC1), and glucosamine-6-phosphate deaminase gene (NAG1) in the same background strain had no obvious effect on white-gray-opaque transitions. Our findings suggest that the GlcNAc kinase, Hxk1, may function as a morphological regulator independent on its catabolic role in C. albicans.

205. Cytotoxic and Immunotherapeutic Effects of Toca 511 and 5-Fluorocytosine in an Intraperitoneal Model of Metastatic Colorectal Cancer

Toca 511 (vocimagene amiretrorepvec), a gamma retroviral replicating vector encoding an optimized yeast cytosine deaminase (CD) gene, selectively replicates and spreads in tumors. In infected cells, CD enzyme is expressed and converts 5-FC (5-fluorocytosine, an orally-available anti-fungal drug) to 5-FU (5-fluorouracil), leading to both direct tumor cytotoxicity and extended immunotherapeutic effects in preclinical models. Toca 511 in combination with Toca FC (extended-release 5-FC) recently entered a Phase 2/3 trial (NCT02414165) in patients with recurrent HGG (high grade glioma). Toca 511 is also under investigation delivered via intravenous (IV) infusion followed by injection into the wall of the resection cavity (NCT01985256), followed by Toca FC, in patients with recurrent HGG. IV administration of vectors is minimally invasive, can easily be repeated if desired, and may be applicable to other tumor types including metastatic colorectal cancer (mCRC). Previously we have shown that IV delivery of Toca 511 in a mouse syngeneic mCRC liver model resulted in expression of CD in tumor foci, but not in adjacent normal liver, and followed by courses of 5-FC resulted in direct tumor response, improved survival, and a systemic anti-tumor immune response. Elevated circulating myeloid-derived suppressor cells (MDSC) are associated with advanced disease stages in CRC patients and failure of immunotherapeutic strategies. We further investigated the effect of intralesional administration of Toca 511 with 5-FC treatment on tumor recurrence and immune infiltrates in a model of CRC brain metastases. A significant decrease in MDSC in spleens and tumors was observed with Toca 511 and 5-FC compared to controls, via in situ production of 5-FU (p=0.03, p<0.0001; respectively). Currently, we are investigating the efficacy of Toca 511 and 5-FC in a mouse syngeneic intraperitoneal (IP) model. We identified the optimal delivery method for treatment of IP metastases, and evaluated survival after IV and IP vector delivery followed by courses of 5-FC. Treatment with Toca 511 and 5-FC led to an improved median survival compared to control. Systemic 5-FU has hematological toxicity even at low doses (20 mg/kg) in both naive and CRC tumor-bearing mice which could have an adverse effect on anti-tumor immune responses. We further evaluated Toca 511 and 5-FC treatment compared to systemic 5-FU in terms of efficacy, hematologic toxicity, and induction of anti-tumor immune responses in the IP mCRC model. The effect of Toca 511 and 5-FC compared to systemic 5-FU on MDSC and other immune cell populations will be presented. Our data provides support for the development of Toca 511 and 5-FC as a unique approach targeting both the tumor and the immune system for the treatment of metastatic cancers such as mCRC. A phase 1 study of IV Toca 511 and Toca FC in solid tumors, including mCRC, is planned (NCT02576665).

128. Targeting a High-Expression FVIII Transgene to Exogenous Locations in the Genome without Disrupting Endogenous Gene Expression

The technology that is now available for targeted genome editing consists of artificial nucleases that create double stranded breaks at specific genomic locations that can then be corrected by intrinsic cellular repair processes. Genome editing can be achieved by exploiting the repair mechanism of homologous recombination by providing a donor vector containing the gene(s) of interest flanked by sequences homologous to the site of the double strand break. To date, gene addition in this manner is targeted to defined inert safe harbor loci. We developed an innovative targeting strategy in which homologous recombination could be utilized to target a transcriptionally active genomic locus without disrupting expression of the endogenous gene. In this manner, essentially any location in the genome becomes a potential safe harbor for homologous recombination-mediated genome editing. One advantage to this strategy is that it allows for transgene expression to be under the precise control of endogenous regulatory elements, rather than using heterologous promoters. Therefore, the optimal locus with the most advantageous regulatory elements to drive transgene expression can be selected for gene addition. Pilot experiments confirmed the expression of exogenous reporter genes (such as the green fluorescent protein or the more therapeutically relevant biologically inert surface selectable marker delta NGFR) from either an exogenous ubiquitous promoter or from the exogenous promoter due to the addition of a T2A element incorporated downstream of the endogenous gene. Notably, expression of the endogenous gene was confirmed to be unaltered. These experiments were performed at three separate genomic locations. To demonstrate the feasibility of this strategy therapeutically however, a high-expression FVIII chimeric transgene (HPFVIII) was incorporated into two distinctly active genomic loci: the IL2R gamma chain locus and the adenosine deaminase locus. The donor vectors utilized contained the cDNA for the endogenous gene locus (either the IL2R gamma chain gene or the adenosine deaminase gene) followed by a ubiquitous promoter intended to drive the expression of HPFVIII, all of which was flanked by one kilobase arms of homology. Both the myeloid erythroid-leukemic K562 cell line and the acute T cell leukemic Jurkat cell line were modified upon nucleofection and confirmed to be targeted by sequencing. Single cell clones were produced and assessed for HPFVIII expression by a one-stage APTT based coagulation assay. Clones were found to express therapeutic levels of FVIII from both loci in both cell types (1 Unit / 2 million cells / 24 hrs). These experiments set the stage for targeting of HPFVIII into hematopoietic stem and progenitor CD34+ cells for the purpose of treating Hemophilia A.

Conservation and Innovation of APOBEC3A Restriction Functions during Primate Evolution.

LINE-1 (long interspersed element-1) retroelements are the only active autonomous endogenous retroelements in human genomes. Their retrotransposition activity has created close to 50% of the current human genome. Due to the apparent costs of this proliferation, host genomes have evolved multiple mechanisms to curb LINE-1 retrotransposition. Here, we investigate the evolution and function of the LINE-1 restriction factor APOBEC3A, a member of the APOBEC3 cytidine deaminase gene family. We find that APOBEC3A genes have evolved rapidly under diversifying selection in primates, suggesting changes in APOBEC3A have been recurrently selected in a host-pathogen "arms race." Nonetheless, in contrast to previous reports, we find that the LINE-1 restriction activity of APOBEC3A proteins has been strictly conserved throughout simian primate evolution in spite of its pervasive diversifying selection. Based on these results, we conclude that LINE-1s have not driven the rapid evolution of APOBEC3A in primates. In contrast to this conserved LINE-1 restriction, we find that a subset of primate APOBEC3A genes have enhanced antiviral restriction. We trace this gain of antiviral restriction in APOBEC3A to the common ancestor of a subset of Old World monkeys. Thus, APOBEC3A has not only maintained its LINE-1 restriction ability, but also evolved a gain of antiviral specificity against other pathogens. Our findings suggest that while APOBEC3A has evolved to restrict additional pathogens, only those adaptive amino acid changes that leave LINE-1 restriction unperturbed have been tolerated.

High expression of the human equilibrative nucleoside transporter 1 gene predicts a good response to decitabine in patients with myelodysplastic syndrome.

BackgroundDespite the efficacy of decitabine treatment in myelodysplastic syndrome (MDS), no definite predictor of response is known. In this study, we investigated whether the expression levels of human equilibrative nucleoside transporter 1 (hENT1), hENT2, deoxycytidine kinase (DCK) and cytidine deaminase (CDA) genes could predict response to decitabine in MDS.MethodsWe performed quantitative real-time PCR in marrow mononuclear cells to examine the expression of hENT1, hENT2, DCK, and CDA prior to therapy in 98 MDS patients initially treated with decitabine. Response and overall survival of patients treated with decitabine were analyzed according to gene expression levels. HENT1 knockdown was performed by shRNA in the SKM-1 cell line, and the effect of this on the demethylation ability of decitabine on long interspersed nucleotide element 1 (LINE1) was investigated.ResultsPatients responding to decitabine presented with significantly higher hENT1 expression levels than non-responders (p = 0.004). Overall response, complete response, and cytogenetic complete response rate in patients with high hENT1 expression (79.4, 41.3, and 43.8 %) were significantly higher than those in patients with low hENT1 expression (48.6, 20.0, and 5.9 %, respectively) (p = 0.004, 0.033, and 0.006, respectively). In higher-risk MDS, patients with high hENT1 expression showed prolonged survival compared with those with low hENT1 expression (22.0 vs 14.0 months; p = 0.027). However, the expression levels of hENT2, DCK, and CDA did not affect response rate. Knockdown of hENT1 in SKM-1 cells weakened the demethylation effect on LINE1 induced by decitabine.ConclusionsHigh expression of hENT1 appears to predict a good response to decitabine and a prolonged survival in higher-risk MDS patients treated with decitabine. HENT1 expression knockdown weakens the demethylation effect of decitabine.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0817-9) contains supplementary material, which is available to authorized users.

Genetic variability within Adenosine Deaminase gene and uterine leiomyomas

ObjectiveThe recent observation of an association of colon cancer with two polymorphic sites within the Adenosine Deaminase (ADA) gene suggests an involvement of these polymorphisms in the development of solid tumors. This prompted us to search for a similar association in uterine leiomyomas. Study designWe have studied 181 women admitted to the hospital for leiomyomas requiring surgical intervention and 248 women of comparable age without clinical signs of leiomyomas. All women were from the White population of Rome and gave verbal consent to participate in the study. The genotypes of three polymorphic sites (ADA1, ADA2, ADA6) of ADA gene were determined by DNA analysis. ResultsA higher proportion of ADA2*1/*1 genotype and of carriers of the ADA6*1 allele was observed in women with leiomyomas as compared to controls. This parallels the association found in colon cancer. ConclusionsThis pattern is identical to that previously observed in colon cancer making the possibility of mere sample chance artifact unlikely and supporting the hypothesis that genetic polymorphisms within the ADA gene could be involved in the susceptibility to solid tumors. Genetic variability within the ADA gene may influence adenosine concentration and in turn the immune response by lymphocytes in solid tumors. On the other hand ADA molecules acting as ecto-enzyme may be involved in the transduction of signals in the cell surface with important effects on tumor development.

Hyperglycemia alters E-NTPDases, ecto-5′-nucleotidase, and ectosolic and cytosolic adenosine deaminase activities and expression from encephala of adult zebrafish (Danio rerio)

Hyperglycemia is the main feature for the diagnosis of diabetes mellitus (DM). Some studies have demonstrated the relationship between DM and dysfunction on neurotransmission systems, such as the purinergic system. In this study, we evaluated the extracellular nucleotide hydrolysis and adenosine deamination activities from encephalic membranes of hyperglycemic zebrafish. A significant decrease in ATP, ADP, and AMP hydrolyses was observed at 111-mM glucose-treated group, which returned to normal levels after 7days of glucose withdrawal. A significant increase in ecto-adenosine deaminase activity was observed in 111-mM glucose group, which remain elevated after 7days of glucose withdrawal. The soluble-adenosine deaminase activity was significantly increased just after 7days of glucose withdrawal. We also evaluated the gene expressions of ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases), ecto-5'-nucleotidase, ADA, and adenosine receptors from encephala of adult zebrafish. The entpd 2a.1, entpd 2a.2, entpd 3, and entpd 8 mRNA levels from encephala of adult zebrafish were decreased in 111-mM glucose-treated and glucose withdrawal groups. The gene expressions of adenosine receptors (adora 1 , adora 2aa , adora 2ab , and adora 2b ) were decreased in 111-mM glucose-treated and glucose withdrawal groups. The gene expression of ADA (ada 2a.1) was decreased in glucose withdrawal group. Maltodextrin, used as a control, did not affect the expression of adenosine receptors, ADA and E-NTPDases 2, 3, and 8, while the expression of ecto-5'-nucleotidase was slightly increased and the E-NTPDases 1 decreased. These findings demonstrated that hyperglycemia might affect the ecto-nucleotidase and adenosine deaminase activities and gene expression in zebrafish, probably through a mechanism involving the osmotic effect, suggesting that the modifications caused on purinergic system may also contribute to the diabetes-induced progressive cognitive impairment.

Dihydropyrimidine Dehydrogenase Is a Prognostic Marker for Mesenchymal Stem Cell-Mediated Cytosine Deaminase Gene and 5-Fluorocytosine Prodrug Therapy for the Treatment of Recurrent Gliomas.

We investigated a therapeutic strategy for recurrent malignant gliomas using mesenchymal stem cells (MSC), expressing cytosine deaminase (CD), and prodrug 5-Fluorocytosine (5-FC) as a more specific and less toxic option. MSCs are emerging as a novel cell therapeutic agent with a cancer-targeting property, and CD is considered a promising enzyme in cancer gene therapy which can convert non-toxic 5-FC to toxic 5-Fluorouracil (5-FU). Therefore, use of prodrug 5-FC can minimize normal cell toxicity. Analyses of microarrays revealed that targeting DNA damage and its repair is a selectable option for gliomas after the standard chemo/radio-therapy. 5-FU is the most frequently used anti-cancer drug, which induces DNA breaks. Because dihydropyrimidine dehydrogenase (DPD) was reported to be involved in 5-FU metabolism to block DNA damage, we compared the survival rate with 5-FU treatment and the level of DPD expression in 15 different glioma cell lines. DPD-deficient cells showed higher sensitivity to 5-FU, and the regulation of DPD level by either siRNA or overexpression was directly related to the 5-FU sensitivity. For MSC/CD with 5-FC therapy, DPD-deficient cells such as U87MG, GBM28, and GBM37 showed higher sensitivity compared to DPD-high U373 cells. Effective inhibition of tumor growth was also observed in an orthotopic mouse model using DPD- deficient U87MG, indicating that DPD gene expression is indeed closely related to the efficacy of MSC/CD-mediated 5-FC therapy. Our results suggested that DPD can be used as a biomarker for selecting glioma patients who may possibly benefit from this therapy.

Targeted Treatment of Experimental Spinal Cord Glioma With Dual Gene-Engineered Human Neural Stem Cells.

There are currently no satisfactory treatments or experimental models showing autonomic dysfunction for intramedullary spinal cord gliomas (ISCG). To develop a rat model of ISCG and investigate whether genetically engineered human neural stem cells (F3.hNSCs) could be developed into effective therapies for ISCG. Immunodeficient/Rowett Nude rats received C6 implantation of G55 human glioblastoma cells (10K/each). F3.hNSCs engineered to express either cytosine deaminase gene only (i.e., F3.CD) or dual genes of CD and thymidine kinase (i.e., F3.CD-TK) converted benign 5-fluorocytosine and ganciclovir into oncolytic 5-fluorouracil and ganciclovir-triphosphate, respectively. ISCG rats received injection of F3.CD-TK, F3.CD, or F3.CD-TK debris near the tumor epicenter 7 days after G55 seeding, followed with 5-FC (500 mg/kg/5 mL) and ganciclovir administrations (25 mg/kg/1 mL/day × 5/each repeat, intraperitoneal injection). Per humane standards for animals, loss of weight-bearing stepping in the hindlimb was used to determine post-tumor survival. Also evaluated were autonomic functions and tumor growth rate in vivo. ISCG rats with F3.CD-TK treatment survived significantly longer (37.5 ± 4.78 days) than those receiving F3.CD (21.5 ± 1.75 days) or F3.CD-TK debris (19.3 ± 0.85 days; n = 4/group; P < .05, median rank test), with significantly improved autonomic function and reduced tumor growth rate. F3.DC-TK cells migrated diffusively into ISCG clusters to mediate oncolytic effect. Dual gene-engineered human neural stem cell regimen markedly prolonged survival in a rat model that emulates somatomotor and autonomic dysfunctions of human cervical ISCG. F3.CD-TK may provide a novel approach to treating clinical ISCG. 5FC, 5-fluorocytosineBBB, Basso, Beattie, and BresnahanCD, cytosine deaminaseDP, diastolic blood pressureGCV, ganciclovir; hNSCs, human neural stem cellsISCG, intramedullary spinal cord gliomasMAP, mean arterial blood pressureNSCs, neural stem cellsSP, systolic blood pressureTK, thymidine kinase.

Exposure to Inflammatory Immune Responses As Driver of Clonal Evolution in Childhood Acute Lymphoblastic Leukemia

Background: Pediatric pre-B acute lymphoblastic leukemia (ALL) may develop from prenatal chromosomal translocations acquired in utero. For instance, the ETV6-RUNX1 gene rearrangement (~25% of childhood ALL) is found in the umbilical cord blood and Guthrie blood spots of 1 in 100 healthy newborns, however, only 1 in 14,000 carriers develop overt leukemia. The molecular mechanisms driving clonal evolution towards overt leukemia were not clear.Rationale: Activation Induced Cytidine Deaminase (AID) and Recombination Activation Genes 1 and 2 (RAG1-RAG2) are genetic modifiers of the immunoglobulin (Ig) genes that are expressed during normal B cell development. Although AID and RAG1/RAG2 are thought to be segregated to early (RAG1/RAG2) and late (AID) stages of B cell development, respectively, we found that the two enzymes can be concurrently expressed during early B-lymphopoiesis in the context of repeated inflammatory stimuli.Results: Our experiments identified transitional pre-B cells as the subset that is particularly vulnerable to concomitant expression of AID and RAG1-RAG2 with earlier B cells being protected by IL7 signaling.Human B cells from children lacking a functional IL-7 receptor (IL-7R) displayed both increased expression and activity of AID concurrently with RAG1-RAG2. These results demonstrated that AID activation in both mouse and human early B cell compartments increases genetic instability. Although concurrent activation of AID and RAG1-RAG2 in patient samples implicated a correlation between the two enzymes in the pathogenesis of leukemia, this as such did not prove that the enzymes causally induce overt leukemogenesis. Therefore, we next evaluated the requirement of AID and RAG1-RAG2 in leukemogenic transformation, and identified a condition that leads to massive activation of these enzymes in a pre-leukemic B cell. Importantly, AID and RAG1-RAG2 expression increased dramatically during inflammatory immune responses (e.g. infection), where both these enzymes diversify the antibody repertoire and improve its affinity to antigens from infectious pathogens. We therefore tested whether the pre-B cell subset that concurrently expresses AID and RAG1-RAG2 can respond to an inflammatory stimulus, such as LPS. We observed that pre-B cells require protection from IL7, which prevents aberrant activation of AID. In the absence of protective IL-7, these pre-B cells acquired responsiveness to LPS and strongly activated AID concurrently with RAG1-RAG2 enzymes. We developed IL7-dependent pre-B cell cultures as a disease model for ETV6-RUNX1 pre-leukemia and tested the role of AID and RAG1 in the progression of pre-leukemic clones. To this end, we expanded ETV6-RUNX1 pre-B cells from wildtype (AID and RAG1 expressing) mice, or from mice lacking AID (Aid-/-Rag1+/+) or RAG1 (Aid+/+Rag1-/-). We then challenged pre-B cell cultures by withdrawal of IL7 (loss of protection) and inflammatory stimuli (LPS) and transplanted pre-B cells that had undergone five cycles of -IL7/LPS challenge. Upon transplanting -IL7/LPS-treated Aid+/+Rag1+/+ or Aid-/-Rag1+/+ or Aid+/+Rag1-/- pre-B cells containing ETV6-RUNX1 into NOD-SCID recipient mice, we observed that loss of either Aid or Rag1 dramatically prolonged the latency and reduced the penetrance of leukemia in transplant recipients. This proved that AID and RAG1-RAG2 causally accelerate clonal evolution of a pre-leukemic B cell towards leukemia. Our findings provide a mechanism by which pre-leukemic clones carrying a prenatal genetic lesion such as ETV6-RUNX1 can evolve through infectious and inflammatory stimuli ultimately leading to full blown leukemia.Conclusion: The impact of inflammatory stimuli on leukemogenesis has been previously implicated in multiple epidemiological studies. For instance, day-care attendance primed the immune system during early childhood and is thought to protect against exacerbation of B cell responses and to prevent collateral damage driving clonal evolution towards leukemia. Although inflammation (LPS stimulation) seems to play a role in accelerating pre-B leukemogenesis in our model, further experiments testing actual infectious pathogens are needed to corroborate this concept. Moreover, it is crucial to test whether leukemogenesis is accelerated in individuals infected with restricted classes of pathogens, not all of which may activate AID in pre-B cells. DisclosuresNo relevant conflicts of interest to declare.

Chemoprotection of murine hematopoietic cells by combined gene transfer of cytidine deaminase (CDD) and multidrug resistance 1 gene (MDR1).

BackgroundHematologic toxicity represents a major side effect of cytotoxic chemotherapy frequently preventing adequately dosed chemotherapy application and impeding therapeutic success. Transgenic (over)expression of chemotherapy resistance (CTX-R) genes in hematopoietic stem- and progenitor cells represents a potential strategy to overcome this problem. To apply this concept in the context of acute myeloid leukemia and myelodysplasia, we have investigated the overexpression of the multidrug resistance 1 (MDR1) and the cytidine deaminase (CDD) gene conferring resistance to anthracyclines and cytarabine (Ara-C), the two most important drugs in the treatment of these diseases.MethodsState-of-the-art, third generation, self-inactivating (SIN) lentiviral vectors were utilized to overexpress a human CDD-cDNA and a codon-optimized human MDR1-cDNA corrected for cryptic splice sites from a spleen focus forming virus derived internal promoter. Studies were performed in myeloid 32D cells as well as primary lineage marker negative (lin−) murine bone marrow cells and flow cytometric analysis of suspension cultures and clonogenic analysis of vector transduced cells following cytotoxic drug challenge were utilized as read outs.ResultsEfficient chemoprotection of CDD and MDR1 transduced hematopoietic 32D as well as primary lin− cells was proven in the context of Ara-C and anthracycline application. Both, CTX-R transduced 32D as well as primary hematopoietic cells displayed marked resistance at concentrations 5–20 times the LD50 of non-transduced control cells. Moreover, simultaneous CDD/MDR1 gene transfer resulted in similar protection levels even when combined Ara-C anthracycline treatment was applied. Furthermore, significant enrichment of transduced cells was observed upon cytotoxic drug administration.ConclusionsOur data demonstrate efficient chemoprotection as well as enrichment of transduced cells in hematopoietic cell lines as well as primary murine hematopoietic progenitor cells following Ara-C and/or anthracycline application, arguing for the efficacy as well as feasibility of our approach and warranting further evaluation of this concept.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-015-0260-4) contains supplementary material, which is available to authorized users.

Exogenous spermidine is enhancing tomato tolerance to salinity-alkalinity stress by regulating chloroplast antioxidant system and chlorophyll metabolism.

BackgroundSalinity–alkalinity stress is known to adversely affect a variety of processes in plants, thus inhibiting growth and decreasing crop yield. Polyamines protect plants against a variety of environmental stresses. However, whether exogenous spermidine increases the tolerance of tomato seedlings via effects on chloroplast antioxidant enzymes and chlorophyll metabolism is unknown. In this study, we examined the effect of exogenous spermidine on chlorophyll synthesis and degradation pathway intermediates and related enzyme activities, as well as chloroplast ultrastructure, gene expression, and antioxidants in salinity–alkalinity–stressed tomato seedlings.ResultsSalinity–alkalinity stress disrupted chlorophyll metabolism and hindered uroorphyrinogen III conversion to protoporphyrin IX. These effects were more pronounced in seedlings of cultivar Zhongza No. 9 than cultivar Jinpengchaoguan. Under salinity–alkalinity stress, exogenous spermidine alleviated decreases in the contents of total chlorophyll and chlorophyll a and b in seedlings of both cultivars following 4 days of stress. With extended stress, exogenous spermidine reduced the accumulation of δ–aminolevulinic acid, porphobilinogen, and uroorphyrinogen III and increased the levels of protoporphyrin IX, Mg–protoporphyrin IX, and protochlorophyllide, suggesting that spermidine promotes the conversion of uroorphyrinogen III to protoporphyrin IX. The effect occurred earlier in cultivar Jinpengchaoguan than in cultivar Zhongza No. 9. Exogenous spermidine also alleviated the stress–induced increases in malondialdehyde content, superoxide radical generation rate, chlorophyllase activity, and expression of the chlorophyllase gene and the stress–induced decreases in the activities of antioxidant enzymes, antioxidants, and expression of the porphobilinogen deaminase gene. In addition, exogenous spermidine stabilized the chloroplast ultrastructure in stressed tomato seedlings.ConclusionsThe tomato cultivars examined exhibited different capacities for responding to salinity–alkalinity stress. Exogenous spermidine triggers effective protection against damage induced by salinity–alkalinity stress in tomato seedlings, probably by maintaining chloroplast structural integrity and alleviating salinity–alkalinity–induced oxidative damage, most likely through regulation of chlorophyll metabolism and the enzymatic and non–enzymatic antioxidant systems in chloroplast. Exogenous spermidine also exerts positive effects at the transcription level, such as down–regulation of the expression of the chlorophyllase gene and up–regulation of the expression of the porphobilinogen deaminase gene.

IMCT-04TOCA 5: PHASE 2/3 RANDOMIZED, OPEN-LABEL STUDY OF TOCA 511 WITH TOCA FC VERSUS STANDARD OF CARE IN PATIENTS UNDERGOING PLANNED RESECTION FOR RECURRENT HIGH GRADE GLIOMA (NCT02414165)

Recurrent glioblastoma and anaplastic astrocytoma have a dismal prognosis and a high unmet need for effective therapies. Toca 511 is a retroviral replicating vector derived from a cloned Moloney murine leukemia virus with the original ecotropic envelope gene replaced with an amphotropic envelope gene to enable the virus to infect human cells. A modified yeast cytosine deaminase (CD) gene has been inserted into this vector. The expressed CD enzyme catalyzes conversion of antifungal drug 5-flucytosine (administered as investigational extended-release formulation Toca FC) to antineoplastic drug 5-fluorouracil. Toca 5 is a multicenter, randomized, open-label Phase 2/3 trial of Toca 511 and Toca FC versus standard of care (Investigator's choice of single agent lomustine, temozolomide, or bevacizumab) administered to patients undergoing resection for first or second recurrence of glioblastoma or anaplastic astrocytoma. The trial will enroll approximately 370 patients (Phase 2-170 and Phase 3-200). Primary endpoint is overall survival (OS). Key secondary endpoints are safety, objective response rate, clinical benefit rate, progression-free survival, and landmark OS. Key inclusion criteria are age 18-75 years, histologically proven glioblastoma or anaplastic astrocytoma, measurable disease preoperatively of at least 1 cm, candidate for ≥ 80% resection of enhancing tumor based on pre-operative evaluation, KPS ≥ 70. Selected exclusion criteria are enhancing tumor > 5 cm, more than two prior recurrences and prior bevacizumab other than for newly diagnosed glioma. Assays will be performed to evaluate evidence for immunologic mechanisms of disease control, including tumor reactive PBMC measurement by stimulation via ex vivo glioma antigen presentation, flow cytometry based phenotyping of PBMCs with an effector, memory, Treg, and myeloid derived suppressor cell panel. Molecular profiling of resected tumor samples will be correlated with primary and secondary endpoints to identify potential biomarkers for treatment-related response. Toca 5 is expected to begin enrollment in 3Q 2015.

CBIO-40THREE-DIMENSIONAL ASSESSMENT OF BYSTANDER EFFECTS OF MESENCHYMAL STEM CELLS CARRYING A CYTOSINE DEAMINASE GENE ON GLIOMA CELLS

Stem cells carrying a suicide gene have emerged as therapeutic candidates for their cytotoxic bystander effects on neighboring cancers, while being non-toxic to other parts of the body. However, traditional cytotoxicity assays are unable to adequately assess the therapeutic effects of bystander cells. Here, we report a method to assess bystander effects of therapeutic stem cells against 3-dimensionally grown glioma cells in real time. U87 glioma cells were stably transduced to express a green fluorescence protein and co-cultivated with mesenchymal stem cells engineered to carry a bacterial cytosine deaminase gene (MSC/CD). Following addition of a 5-fluorocytine (5-FC) prodrug to the co-culture, fluorescence from U87 cells was obtained and analyzed in real time. Notably, the IC50 of 5-FC was higher when U87 cells were grown 3-dimensionally in soft agar medium for 3 weeks, as compared to those grown for one week in two-dimensional monolayer cultures. Additionally, more MSC/CD cells were required to maintain a similar level of efficacy. Since three-dimensional growth of glioma cells under our co-culture condition mimics the long-term expansion of cancer cells in vivo, our method can extend to an in vitro assay system to assess stem cell-mediated anti-cancer effects before advancing into preclinical animal studies.

Modulatory effect of iron chelators on adenosine deaminase activity and gene expression in Trichomonas vaginalis.

Trichomonas vaginalis is a flagellate protozoan that parasitises the urogenital human tract and causes trichomoniasis. During the infection, the acquisition of nutrients, such as iron and purine and pyrimidine nucleosides, is essential for the survival of the parasite. The enzymes for purinergic signalling, including adenosine deaminase (ADA), which degrades adenosine to inosine, have been characterised in T. vaginalis. In the evaluation of the ADA profile in different T. vaginalis isolates treated with different iron sources or with limited iron availability, a decrease in activity and an increase in ADA gene expression after iron limitation by 2,2-bipyridyl and ferrozine chelators were observed. This supported the hypothesis that iron can modulate the activity of the enzymes involved in purinergic signalling. Under bovine serum limitation conditions, no significant differences were observed. The results obtained in this study allow for the assessment of important aspects of ADA and contribute to a better understanding of the purinergic system in T. vaginalis and the role of iron in establishing infection and parasite survival.

Oncolytic virotherapy with an armed vaccinia virus in an orthotopic model of renal carcinoma is associated with modification of the tumor microenvironment

ABSTRACTOncolytic virotherapy is an emergent promising therapeutic approach for the treatment of cancer. We have constructed a vaccinia virus (WR strain) deleted for thymidine kinase (TK) and ribonucleotide reductase (RR) genes that expressed the fusion suicide gene FCU1 derived from the yeast cytosine deaminase and uracil phosphoribosyltransferase genes. We evaluated this construct (VV-FCU1) in the orthotopic model of renal carcinoma (RenCa). Systemic administration of VV-FCU1 resulted in orthotopic tumor growth inhibition, despite temporary expression of viral proteins. VV-FCU1 treatment was associated with an infiltration of tumors by CD8+ T lymphocytes and a decrease in the proportion of infiltrating Tregs, thus modifying the ratio of CD8+/CD4+ Treg in favor of CD8+cytotoxic T cells. We demonstrated that VV-FCU1 treatment prolonged survival of animals implanted with RenCa cells in kidney. Depletion of CD8+ T cells abolished the therapeutic effect of VV-FCU1 while depletion of CD4+ T cells enhanced its protective activity. Administration of the prodrug 5-fluorocytosine (5-FC) resulted in a sustained control of tumor growth but did not extend survival. This study shows the importance of CD4+ and CD8+ T cells in vaccinia virus-mediated oncolytic virotherapy and suggests that this approach may be evaluated for the treatment of human renal cell carcinoma.

Acute intermittent porphyria: Long-term follow up of 35 patients

Background and objectivesAcute intermittent porphyria (AIP) is a rare disease that results from a deficiency of porphobilinogen deaminase, the third enzyme of the heme biosynthetic pathway. AIP carriers are at risk of presenting acute neurovisceral attacks associated with overproduction of heme-precursors in the liver. Patients and methodWe report the characteristics of all AIP patients attended in the Hospital Clinic of Barcelona during the years 1993–2013 and their long-term follow-up. ResultsThirty-five AIP patients (33 women, 2 men) experienced acute attacks. Treatment with hemin resolved the acute neurovisceral crisis in all cases. Nine patients presented peripheral neuropathy and persistent sequelae. Long-term follow-up allowed classifying the patients into groups: A, patients with acute symptoms during 1–2 years and subsequent long-lasting clinical remission (n=24) or a few sporadic crises (n=3), and B, patients with recurrent attacks requiring chronic administration of hemin (n=8). In a majority of the patients of group A, the urinary excretion of heme-precursors decreased gradually over time. However, the chronic hemin regime did not induce a decline of urinary heme-precursors in the patients of group B. Additionally, we identified 44 asymptomatic AIP carriers, most (70.5%) with normal values of heme-precursors in urine. ConclusionsA majority of the AIP patients of our series achieved a long-lasting clinical remission. A minority (23%) presented recurrent attacks that required chronic hemin infusions without feasible interruption and without long-term biochemical remission. The type of mutation within the porphobilinogen deaminase gene and also life-style related factors may determine remission time-course.