Riki Perlman

The Oncolytic Activity of Newcastle Disease Virus NDV-HUJ on Chemoresistant Primary Melanoma Cells Is Dependent on the Proapoptotic Activity of the Inhibitor of Apoptosis Protein Livin

ABSTRACT Patients with advanced melanoma usually do not benefit from conventional chemotherapy treatment. There is therefore a true need for a new kind of therapy for melanoma. One factor responsible for the poor prognosis of melanoma is the inhibitor of apoptosis protein (IAP) family member Livin. In this study, we applied a novel approach for the treatment of melanoma, using a unique strain of the oncolytic Newcastle disease virus (NDV-HUJ). We found that, unlike chemotherapeutic drugs, NDV-HUJ, a one-cycle replicating virus, overcomes the resistance to apoptosis of melanoma primary cultures that over express the Livin protein. In contrast, melanoma tumor cells that do not express Livin are relatively resistant to NDV-HUJ treatment. Furthermore, we show that NDV-HUJ-induced oncolysis is attributed to the dual function of Livin: although Livin inhibits apoptosis through the inhibition of caspases, under the robust apoptotic stimulation of NDV-HUJ, caspases can cleave Livin to create a truncated protein with a paradoxical proapoptotic activity. Thus, NDV-HUJ is a potent inducer of apoptosis that can overcome the antiapoptotic effect of Livin and allow cleavage of Livin into the proapoptotic tLivin protein. Moreover, the results indicate that the interferon system, which is functional in melanoma, is not involved in NDV-induced oncolysis. Taken together, our data offer the possibility of a new viral oncolytic treatment for chemoresistant melanoma.

Transmembrane signalling in Saccharomyces cerevisiae

Bakers yeast, a unicellular eukaryote, has been a model organism for biochemists, geneticists and most recently for molecular biologists. Pioneering biochemical studies were conducted on yeast, such as the study of glucose fermentation and amino acid metabolism. The powerful tools of yeast genetics have allowed a comprehensive study of important issues such as the cell cycle and meiosis. In recent years, it has been established that Saccharomyces cerevisiae, the most extensively characterized of the yeasts, shares key molecules and biochemical pathways with higher eukaryotes. For example, actin, tubulin, ubiquitin, calmodulin, GTP regulatory proteins, different protein kinases including protein tyrosine kinases, were all found to play central roles in yeast. Furthermore, structurally homologous proteins, as well as transcription regulating elements, of yeast and higher eukaryotes, including mammals, were shown to be structurally and functionally interchangeable. It has also been found that yeast can express human genes. Technically, yeasts are simple to handle, inexpensive to grow, complete a cell cycle within 90 min, and therefore can yield relatively quick results. These qualities are useful in biotechnological applications. Saccharomyces cerevisiae, can be genetically manipulated fairly easily, and has been tinkered with more than any other system. A cloned, in vitro mutated gene, can be transformed into wild type yeast and by homologous recombination, can replace the native gene and generate the desired mutant. Such manipulations, not possible yet in other eukaryotic cells, allow the precise definition of the role played by different genes and their domains. These unique features of Saccharomyces cerevisiae, together with rapidly evolving techniques of molecular biology, have made it a successful model organism for the study of numerous questions.(ABSTRACT TRUNCATED AT 250 WORDS)

The Inhibitor of Apoptosis Protein Livin (ML-IAP) Plays a Dual Role in Tumorigenicity

The inhibitor of apoptosis protein (IAP) family can inhibit apoptosis induced by a variety of stimuli. We and others previously described the IAP Livin (ML-IAP). We found that Livin is unique among the IAP members as, on a strong apoptotic stimulus, it is specifically cleaved by caspases to produce a truncated protein with paradoxical proapoptotic activity (tLivin). We also showed that Livin encodes two splicing variants, termed Livin alpha and beta, with diverse antiapoptotic effects in vitro. In this study, we compared the Livin isoforms in vivo. An animal model was established and the effects of Livin alpha and beta on the initiation and development of tumors were compared. In the animal model, Livin alpha promotes tumor initiation in comparison with control. Interestingly, the growth of tumors originating from cells expressing Livin beta was inhibited. In these tumors, Livin beta was cleaved and produced a high level of the proapoptotic tLivin beta that repressed tumor development. When we eliminated the proapoptotic effect of Livin beta by point mutations, the resulting antiapoptotic Livin beta mutants contributed to tumor progression. In terms of mechanism, we show that Livin beta tumors develop only in mice lacking natural killer (NK) cell activity. Thus, from the animal model, we can conclude that Livin plays a major role in tumorigenicity and that NK cells induce cleavage of Livin to its proapoptotic truncated protein that in turn inhibits tumor growth. Therefore, Livin and tLivin may serve as potential targets for cancer therapy.

Transmembrane signaling in Saccharomyces cerevisiae as a model for signaling in metazoans: state of the art after 25 years.

In the very first article that appeared in Cellular Signalling, published in its inaugural issue in October 1989, we reviewed signal transduction pathways in Saccharomyces cerevisiae. Although this yeast was already a powerful model organism for the study of cellular processes, it was not yet a valuable instrument for the investigation of signaling cascades. In 1989, therefore, we discussed only two pathways, the Ras/cAMP and the mating (Fus3) signaling cascades. The pivotal findings concerning those pathways undoubtedly contributed to the realization that yeast is a relevant model for understanding signal transduction in higher eukaryotes. Consequently, the last 25 years have witnessed the discovery of many signal transduction pathways in S. cerevisiae, including the high osmotic glycerol (Hog1), Stl2/Mpk1 and Smk1 mitogen-activated protein (MAP) kinase pathways, the TOR, AMPK/Snf1, SPS, PLC1 and Pkr/Gcn2 cascades, and systems that sense and respond to various types of stress. For many cascades, orthologous pathways were identified in mammals following their discovery in yeast. Here we review advances in the understanding of signaling in S. cerevisiae over the last 25 years. When all pathways are analyzed together, some prominent themes emerge. First, wiring of signaling cascades may not be identical in all S. cerevisiae strains, but is probably specific to each genetic background. This situation complicates attempts to decipher and generalize these webs of reactions. Secondly, the Ras/cAMP and the TOR cascades are pivotal pathways that affect all processes of the life of the yeast cell, whereas the yeast MAP kinase pathways are not essential. Yeast cells deficient in all MAP kinases proliferate normally. Another theme is the existence of central molecular hubs, either as single proteins (e.g., Msn2/4, Flo11) or as multisubunit complexes (e.g., TORC1/2), which are controlled by numerous pathways and in turn determine the fate of the cell. It is also apparent that lipid signaling is less developed in yeast than in higher eukaryotes. Finally, feedback regulatory mechanisms seem to be at least as important and powerful as the pathways themselves. In the final chapter of this essay we dare to imagine the essence of our next review on signaling in yeast, to be published on the 50th anniversary of Cellular Signalling in 2039.

Subcellular localization determines the delicate balance between the anti- and pro-apoptotic activity of Livin.

Livin is a member of the Inhibitor of Apoptosis Protein family which inhibits apoptosis induced by a variety of stimuli. We previously identified Livin and demonstrated that following apoptotic stimuli, Livin is cleaved by effector caspases to produce a truncated form with paradoxical pro-apoptotic activity. In the present study, we reveal that while full-length Livin shows diffuse cytoplasmic localization, truncated Livin (tLivin) is found in a peri-nuclear distribution with marked localization to the Golgi apparatus. Using mutation analysis, we identified two domains that are crucial for the pro-apoptotic activity of tLivin: the N-terminal region of tLivin which is exposed by cleavage, and the RING domain. We demonstrate that, of the N-terminal sequence, only the first N-terminal glycine residue dictates the peri-nuclear distribution of tLivin. However, while the perinuclear localization of tLivin is essential, it is not sufficient for tLivin to exert its pro-apoptotic function. Once tLivin is properly localized, an intact RING domain enables its pro-apoptotic function.

The Clinical Effect of the Inhibitor of Apopotosis Protein Livin in Melanoma

Objective: The inhibitor of apoptosis protein (IAP) livin is frequently overexpressed in melanoma. Livin binds caspases and thereby inhibits apoptosis. We found that caspases cleave livin to produce a truncated form with a paradoxical proapoptotic activity. Methods: We assessed the correlation of livin expression with survival among 114 melanoma patients treated with an autologous melanoma vaccine. In 52 patients, resection resulted in no evidence of disease (NED) and 62 remained with active disease (WAD). Protein levels were assessed using Western blot. Results: We found livin protein expression in 44/114 samples (38.4%). Median overall survival was 1.4 years in NED patients with high levels of livin protein, 8.4 years in those with low-intermediate levels and not reached in patients who did not express livin (p = 0.025). The corresponding overall survival was 2.3 years among WAD patients with high levels of livin protein, 11.3 years in those with low-intermediate levels and, paradoxically, only 4.0 years in patients who did not express livin (p = 0.012). Conclusion: Livin protein expression may play a role in the progression of melanoma and correlates with survival. A high level of the protein is associated with a poor prognosis. However, in WAD patients low to intermediate level of livin, rather than absence of the protein, is associated with a favorable prognosis. This is probably due to the paradoxical proapoptotic activity of this important regulator of apoptosis.

Extracellular matrix constituents interfere with Newcastle disease virus spread in solid tissue and diminish its potential oncolytic activity

Advanced melanoma cells, characterized by resistance to chemotherapy, have been shown to be highly sensitive to oncolysis by Newcastle disease virus (NDV). In the present study, we investigated the capacity of NDV to specifically infect and spread into solid tissues of human melanoma and lung carcinoma, in vivo and ex vivo. For this purpose a new model of SCID-beige mice implanted with human melanoma was developed. Surprisingly, the replication competent NDV-MTH and the attenuated, single-cycle replication NDV-HUJ strains, demonstrated a similar oncolytic activity in the melanoma-implanted mice. Further, ex vivo analysis, using organ cultures derived from the melanoma tissues indicated a limited spread of the two NDV strains in the tissue. Extracellular matrix (ECM) molecules, notably heparin sulfate and collagen, were found to limit viral spread in the tissue. This observation was validated with yet another solid tumour of human lung carcinoma. Taken together, the results indicate that the ECM acts as a barrier to virus spread within solid tumour tissues and that this restriction must be overcome to achieve effective oncolysis with NDV.

Janus Kinase V617F mutation in cigarette smokers

The JAK2 V617F mutation is responsible for the constitutive activation of the erythropoietin receptor signaling pathway in most cases of polycythemia vera (PV). The mutation has also been described in healthy people. As smoking may result in secondary polycythemia, the goal of this trial was to examine the effect of smoking on the prevalence of the JAK2 mutation and its correlation to erythrocytosis. The study was case–control. Hospitalized smokers (n = 81) and nonsmokers (n = 61) were recruited. Serum was drawn for complete blood count, erythropoietin, ferritin and venous blood gases. JAK2 mutation was analyzed by highly sensitive allele‐specific Quantitative Real Time PCR. The JAK2 mutation was found in 29/81 (35.8%) of smokers in comparison to only 9/61 (14.8%) of the control group (P = 0.007). The frequency of the mutation among smokers who were positive for the JAK2 mutation had a mean of 6.78 × 10−4 ± 1.08 × 10−3 vs. 1.51 × 10−4 ± 2.04 × 10−4 among nonsmokers (P = 0.027). Both frequencies are much lower than those found in PV. There was a medium correlation between older age and mutation frequency in nonsmokers (r= 0.67, P = 0.043). Hematocrit was higher in smokers (47.8 ± 6 vs. 41.7 ± 4.7, P < 0.0001), but no correlation was found to JAK2 mutation. In a cohort of hospitalized smokers and nonsmokers, JAK2 mutation was more prevalent and found in higher frequencies among smokers than nonsmokers. We suggest that accelerated erythropoiesis renders the cells susceptible to JAK2 mutation. Am. J. Hematol., 2011.

Bortezomib-induced peripheral neuropathy is related to altered levels of brain-derived neurotrophic factor in the peripheral blood of patients with multiple myeloma

Loss of nerve growth factor-mediated neuronal survival has recently been proposed as a candidate mechanism underlying bortezomib-induced peripheral neuropathy (BIPN) (Broyl et al, 2010). However the literature does not reveal any data from patients that can support this hypothesis. Brain-derived neurotrophic factor (BDNF) is a neuronal growth factor that is crucial for neuronal survival and repair (Hofer & Barde, 1988). We report on alterations in BDNF peripheral blood levels and the development of BIPN in patients with multiple myeloma (MM). Following approval of the Ethics Committee and obtaining patient’s informed consent, peripheral neuropathy was assessed and graded in 25 MM patients using the abbreviated version of the Total Neuropathy Score (TNS) tool (Argyriou et al, 2008). These patients were examined at diagnosis and after receiving four courses of a bortezomib-based regimen given intravenously either weekly or biweekly (Table I). Patients that developed TNS ≥ 2 during treatment were determined to have BIPN and three patients with TNS ≥ 2 at diagnosis were excluded from the study. At the time of neurological examination, a venous blood sample was obtained and soluble BDNF (sBDNF) level was determined by a commercial enzyme-linked immunosorbent assay kit (R&D Systems, Minneapolis, MN, USA) in platelet-poor-plasma. One of our patients passed away after two courses of bortezomib. Eight of the remaining patients (36%) developed BIPN. We found lower levels of sBDNF in the plasma of patients that developed BIPN as compared to patients that did not develop BIPN [BDNF level standard deviation (SD) in BIPN 2 164 0 721 vs. 4 62 0 61 ng/ml in non-BIPN; P = 0 007; Fig 1A]. By analysing the difference between BDNF levels at diagnosis and after four courses of treatment of each patient, we demonstrated that sBDNF level was reduced in patients developing BIPN while it remained stable or even minimally elevated in patients that did not develop BIPN (difference in BDNF SD in BIPN 1 668 0 670 vs. 0 405 0 708 ng/ml in non-BIPN P = 0 02) (Fig 1B). Platelets are thought to be responsible for the homeostasis of BDNF in the blood as they take up, store and secrete BDNF (Fujimura et al, 2002). As we did not observe differences in the platelet counts of patients that developed BIPN compared to patients that did not develop BIPN (data not shown), we reasoned that decreased sBDNF levels in the plasma of patients with BIPN may result from lack of secretion of BDNF from the platelets. To test this hypothesis, we determined the content of BDNF in the platelets of patients that developed BIPN relative to those who did not develop BIPN by two different methods. First, platelets that were collected and stored in 20°C at the time of the patients’ examination were lysed and the BDNF immunoreactive band was determined by gel electrophoresis using specific rabbit polyclonal anti-human BDNF mAb (Abcam, Cambridge, MA, USA). Second, BDNF and the platelet activation marker CD62p were determined in freshly isolated platelets of patients with BIPN and patients without BIPN using flow cytometry. Briefly, 20 ll of platelet-rich-plasma from each patient was stained with phycoerythrin-cyanin 5 (PE-CY5) Anti human CD41a monclonal antobody (mAb) (Beckmann Coulter, Brea, CA, USA) and PE anti human CD62p mAb (Biolegends, San Diego, CA, USA) or fixed permeabilized (Invitrogen, Frederick, MD, USA) and stained with ATTO-488 Anti human proBDNF pAb (Alomone Labs Ltd., Jerusalem, Israel). The intensity of surface CD62p or intracellular BDNF signal was determined in 10 000 platelets. Analysis of BDNF in platelets by gel electrophoresis suggested that BDNF content was increased in platelets of patients who developed BIPN as compared to platelets of patients that did not (mean BDNF expression level post-treatment relative to pre-treatment SD in BIPN 4 33 1 15-fold vs. 1 67 0 57-fold in non-BIPN P = 0 02) (Fig 1C). Flow cytometric analysis confirmed the increase of BDNF content in platelets of patients with BIPN, as detected by higher intensity of proBDNF compared to platelets of patients without BIPN [mean fluorescence intensity (MFI) of BDNF SD in BIPN 43 12 6 04 vs. 18 267 10 162 ng/ml in non-BIPN P = 0 009]. As expected, the increased BDNF signal in platelets of patients with BIPN coincided with lower

Associations between B-cell non-Hodgkin lymphoma and exposure, persistence and immune response to hepatitis B.

Although 90–95% of adults recover completely from Hepatitis B (HBV) infection, a minority are unable to clear the virus.[1][1] Epidemiological studies have demonstrated an increased risk of B-NHL among those with persistent HBV and B-NHL.[2][2]–[5][3] However, the roles of exposure per se,