Publications by authors named "David Sharon"

29 Publications

  • Page 1 of 1

Nicotinamide phosphoribosyltransferase inhibitors selectively induce apoptosis of AML stem cells by disrupting lipid homeostasis.

Cell Stem Cell 2021 Jul 12. Epub 2021 Jul 12.

Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada; Department of Medicine, University of Toronto, ON, Canada; Division of Medical Oncology and Hematology, Department of Medicine, University Health Network, Toronto, ON, Canada. Electronic address:

Current treatments for acute myeloid leukemia (AML) are often ineffective in eliminating leukemic stem cells (LSCs), which perpetuate the disease. Here, we performed a metabolic drug screen to identify LSC-specific vulnerabilities and found that nicotinamide phosphoribosyltransferase (NAMPT) inhibitors selectively killed LSCs, while sparing normal hematopoietic stem and progenitor cells. Treatment with KPT-9274, a NAMPT inhibitor, suppressed the conversion of saturated fatty acids to monounsaturated fatty acids, a reaction catalyzed by the stearoyl-CoA desaturase (SCD) enzyme, resulting in apoptosis of AML cells. Transcriptomic analysis of LSCs treated with KPT-9274 revealed an upregulation of sterol regulatory-element binding protein (SREBP)-regulated genes, including SCD, which conferred partial protection against NAMPT inhibitors. Inhibition of SREBP signaling with dipyridamole enhanced the cytotoxicity of KPT-9274 on LSCs in vivo. Our work demonstrates that altered lipid homeostasis plays a key role in NAMPT inhibitor-induced apoptosis and identifies NAMPT inhibition as a therapeutic strategy for targeting LSCs in AML.
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http://dx.doi.org/10.1016/j.stem.2021.06.004DOI Listing
July 2021

A mean-field approach for modeling the propagation of perturbations in biochemical reaction networks.

Eur J Pharm Sci 2021 Oct 24;165:105919. Epub 2021 Jun 24.

Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada.

Often, the time evolution of a biochemical reaction network is crucial for determining the effects of combining multiple pharmaceuticals. Here we illustrate a mathematical framework for modeling the dominant temporal behaviour of a complicated molecular pathway or biochemical reaction network in response to an arbitrary perturbation, such as resulting from the administration of a therapeutic agent. The method enables the determination of the temporal evolution of a target protein as the perturbation propagates through its regulatory network. The mathematical approach is particularly useful when the experimental data that is available for characterizing or parameterizing the regulatory network is limited or incomplete. To illustrate the method, we consider the examples of the regulatory networks for the target proteins c-Myc and Chop, which play an important role in venetoclax resistance in acute myeloid leukemia. First we show how the networks that regulate each target protein can be reduced to a mean-field model by identifying the distinct effects that groups of proteins in the regulatory network have on the target protein. Then we show how limited protein-level data can be used to further simplify the mean-field model to pinpoint the dominant effects of the network perturbation on the target protein. This enables a further reduction in the number of parameters in the model. The result is an ordinary differential equation model that captures the temporal evolution of the expression of a target protein when one or more proteins in its regulatory network have been perturbed. Finally, we show how the dominant effects predicted by the mathematical model agree with RNA sequencing data for the regulatory proteins comprising the molecular network, despite the model not having a priori knowledge of this data. Thus, while the approach gives a simplified model for the expression of the target protein, it allows for the interpretation of the effects of the perturbation on the regulatory network itself. This method can be easily extended to sets of target proteins to model components of a larger systems biology model, and provides an approach for partially integrating RNA sequencing data and protein expression data. Moreover, it is a general approach that can be used to study drug effects on specific protein(s) in any disease or condition.
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http://dx.doi.org/10.1016/j.ejps.2021.105919DOI Listing
October 2021

The Perspective of a Breast Cancer Patient: A Survey Study Assessing Needs and Expectations.

Cureus 2020 Jul 13;12(7):e9171. Epub 2020 Jul 13.

Hospice and Palliative Care, Monmouth Medical Center, Long Branch, USA.

Background Patient satisfaction is one of the key indicators of health care quality. We aim to identify patient's needs and expectations in a breast cancer clinic to provide patient-centered care and better overall satisfaction.  Methods A 17-item survey was administered to 110 patients at a breast cancer clinic. The survey was designed after a thorough literature review and approved by an oncologist and a palliative care physician.  Results Self-reported knowledge about the disease was reported adequate by 90.9% of our patients yet only 55.45% of our patients could identify the stage of their cancer. More education was desired by 32.7% of patients including various treatment options (29%), common complications (24.5%), prognosis (26.3%) and risk factors (11.8%). The majority of our patients were having some form of cancer-related emotional stress and physical symptoms. The majority of our patients (57.27%) wanted their oncologist to address social/emotional issues and 25.45% felt the need for more focus on physical symptoms in their subsequent visits. End-of-life (EoL) care discussions were considered an integral component of overall care by 29% of our patients. Components of EoL care discussions that patients stated they could benefit from included prognosis (27.27%), life expectancy (29%), the treatment effect on the quality of life (22.7%), palliative care (9%), hospice (10.9%), advance directives (11.8%), and family involvement in medical decision-making (13.6%). There was a difference noted regarding their EoL care discussion based on the stage of cancer. Patients with early-stage disease wanted their oncologists to decide on the frequency of this discussion (72.7%). Patients with advanced disease wanted EoL care discussion to be done more frequently as initiated by them or their oncologist or if there's a change in the treatment plan.  Conclusions A discrepancy between self-reported and actual knowledge in breast cancer patients emphasizes the need for patient education. Most patients rely on their oncologists for their diagnosis-related emotional and social issues. Surprisingly, more than a quarter of our patients consider EoL care discussions important even though the majority of our patients were healthy and having stage I and II disease.
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http://dx.doi.org/10.7759/cureus.9171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7398723PMC
July 2020

A pooled genome-wide screening strategy to identify and rank influenza host restriction factors in cell-based vaccine production platforms.

Sci Rep 2020 07 22;10(1):12166. Epub 2020 Jul 22.

Department of Bioengineering, McGill University, McConnell Engineering Building, Room 363, 3480 Rue University, Montreal, QC, H3A 2K6, Canada.

Cell-derived influenza vaccines provide better protection and a host of other advantages compared to the egg-derived vaccines that currently dominate the market, but their widespread use is hampered by a lack of high yield, low cost production platforms. Identification and knockout of innate immune and metabolic restriction factors within relevant host cell lines used to grow the virus could offer a means to substantially increase vaccine yield. In this paper, we describe and validate a novel genome-wide pooled CRISPR/Cas9 screening strategy that incorporates a reporter virus and a FACS selection step to identify and rank restriction factors in a given vaccine production cell line. Using the HEK-293SF cell line and A/PuertoRico/8/1934 H1N1 influenza as a model, we identify 64 putative influenza restriction factors to direct the creation of high yield knockout cell lines. In addition, gene ontology and protein complex enrichment analysis of this list of putative restriction factors offers broader insights into the primary host cell determinants of viral yield in cell-based vaccine production systems. Overall, this work will advance efforts to address the public health burden posed by influenza.
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http://dx.doi.org/10.1038/s41598-020-68934-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7376217PMC
July 2020

Disrupting Mitochondrial Copper Distribution Inhibits Leukemic Stem Cell Self-Renewal.

Cell Stem Cell 2020 06 15;26(6):926-937.e10. Epub 2020 May 15.

Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada. Electronic address:

Leukemic stem cells (LSCs) rely on oxidative metabolism and are differentially sensitive to targeting mitochondrial pathways, which spares normal hematopoietic cells. A subset of mitochondrial proteins is folded in the intermembrane space via the mitochondrial intermembrane assembly (MIA) pathway. We found increased mRNA expression of MIA pathway substrates in acute myeloid leukemia (AML) stem cells. Therefore, we evaluated the effects of inhibiting this pathway in AML. Genetic and chemical inhibition of ALR reduces AML growth and viability, disrupts LSC self-renewal, and induces their differentiation. ALR inhibition preferentially decreases its substrate COX17, a mitochondrial copper chaperone, and knockdown of COX17 phenocopies ALR loss. Inhibiting ALR and COX17 increases mitochondrial copper levels which in turn inhibit S-adenosylhomocysteine hydrolase (SAHH) and lower levels of S-adenosylmethionine (SAM), DNA methylation, and chromatin accessibility to lower LSC viability. These results provide insight into mechanisms through which mitochondrial copper controls epigenetic status and viability of LSCs.
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http://dx.doi.org/10.1016/j.stem.2020.04.010DOI Listing
June 2020

Efficacy of Ibrutinib-Based Regimen in Chronic Lymphocytic Leukemia: A Systematic Review.

J Hematol 2019 Mar 30;8(1):1-10. Epub 2019 Mar 30.

Department of Hematology Oncology, Cleveland Clinic, Cleveland, OH, USA.

Ibrutinib has shown to have better efficacy than standard chemoimmunotherapy in del17 positive chronic lymphocytic leukemia (CLL) patients; however its role in del17 negative patients is less clear. We aim to evaluate the efficacy of ibrutinib-based regimens in CLL. Seven databases were searched in accordance with PRISMA statement guidelines using the following keywords: chronic lymphocytic leukemia, CLL, Bruton tyrosine kinase inhibitor, BTK inhibitor, ibrutinib, and PCI-32765. Data from only prospective clinical trials was included. In a phase 3 trial (n = 136), the overall response rate (ORR) with ibrutinib was 92% whereas 18% patients had a complete response (CR). Progression free survival (PFS) and overall survival (OS) at 2 years were 89% and 95% respectively. Phase 3 trial (n = 195) with single agent ibrutinib showed ORR of 63%. PFS at 6 months and OS at 12 months were 88% and 90% respectively. In a phase 2 trial of relapsed and/or refractory (R/R) or high risk treatment naive (TN) patients, combination of ibrutinib and rituximab (n = 104) achieved an ORR of 100% (CR 28%) as compared to ORR 98% (CR 21%) with ibrutinib monotherapy (n = 102) with no significant difference in PFS. Combination of ibrutinib and ublituximab (n = 64) had an ORR of 78% (CR 7%) in a phase 3 study. In del17p negative R/R patients, combination of bendamustine/rituximab (BR) and ibrutinib (n = 289) achieved an ORR of 83% (CR/CRi 10%) and the 18 month PFS was 79%. In a phase 2 trial treated with ibrutinib (n = 145), patients with del17p R/R disease achieved an ORR of 64% and the 24 month PFS and OS was 63% and 75% respectively. In TN del17p patients (n = 35), ORR was 97% (CR-0) and the 24 month PFS and OS were 82% and 84% respectively with single agent ibrutinib. Ibrutinib is the treatment of choice for patients with del17p mutation and has good efficacy in RR/TN patients without del17p mutation. Ibrutinib is being evaluated in combination with rituximab for del17p mutations. Future prospects include combination of ibrutinib with frontline chemotherapy and other novel agents for TN and RR del17p negative patients.
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http://dx.doi.org/10.14740/jh482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7153674PMC
March 2019

The mitochondrial peptidase, neurolysin, regulates respiratory chain supercomplex formation and is necessary for AML viability.

Sci Transl Med 2020 04;12(538)

Princess Margaret Cancer Centre, Toronto, Ontario M5G 1L7, Canada.

Neurolysin (NLN) is a zinc metallopeptidase whose mitochondrial function is unclear. We found that NLN was overexpressed in almost half of patients with acute myeloid leukemia (AML), and inhibition of NLN was selectively cytotoxic to AML cells and stem cells while sparing normal hematopoietic cells. Mechanistically, NLN interacted with the mitochondrial respiratory chain. Genetic and chemical inhibition of NLN impaired oxidative metabolism and disrupted the formation of respiratory chain supercomplexes (RCS). Furthermore, NLN interacted with the known RCS regulator, LETM1, and inhibition of NLN disrupted LETM1 complex formation. RCS were increased in patients with AML and positively correlated with NLN expression. These findings demonstrate that inhibiting RCS formation selectively targets AML cells and stem cells and highlights the therapeutic potential of pharmacologically targeting NLN in AML.
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http://dx.doi.org/10.1126/scitranslmed.aaz8264DOI Listing
April 2020

Repurposing ribosome-targeting antibiotics to overcome resistance to venetoclax in acute myeloid leukemia.

Mol Cell Oncol 2020 28;7(2):1712182. Epub 2020 Jan 28.

Department of Hematology and Medical Oncology, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.

Venetoclax, a selective B-cell lymphoma 2 inhibitor, has shown promise in the treatment of acute myeloid leukemia. However, the development of drug resistance limits its clinical efficacy. In our study, we discovered that ribosome-targeting antibiotics can be repurposed to overcome venetoclax resistance in AML cells through activation of the integrated stress response.
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http://dx.doi.org/10.1080/23723556.2020.1712182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7051130PMC
January 2020

Inhibition of mitochondrial translation overcomes venetoclax resistance in AML through activation of the integrated stress response.

Sci Transl Med 2019 10;11(516)

Princess Margaret Cancer Centre, Toronto, Ontario M5G 1L7, Canada.

Venetoclax is a specific B cell lymphoma 2 (BCL-2) inhibitor with promising activity against acute myeloid leukemia (AML), but its clinical efficacy as a single agent or in combination with hypomethylating agents (HMAs), such as azacitidine, is hampered by intrinsic and acquired resistance. Here, we performed a genome-wide CRISPR knockout screen and found that inactivation of genes involved in mitochondrial translation restored sensitivity to venetoclax in resistant AML cells. Pharmacologic inhibition of mitochondrial protein synthesis with antibiotics that target the ribosome, including tedizolid and doxycycline, effectively overcame venetoclax resistance. Mechanistic studies showed that both tedizolid and venetoclax suppressed mitochondrial respiration, with the latter demonstrating inhibitory activity against complex I [nicotinamide adenine dinucleotide plus hydrogen (NADH) dehydrogenase] of the electron transport chain (ETC). The drugs cooperated to activate a heightened integrated stress response (ISR), which, in turn, suppressed glycolytic capacity, resulting in adenosine triphosphate (ATP) depletion and subsequent cell death. Combination treatment with tedizolid and venetoclax was superior to either agent alone in reducing leukemic burden in mice engrafted with treatment-resistant human AML. The addition of tedizolid to azacitidine and venetoclax further enhanced the killing of resistant AML cells in vitro and in vivo. Our findings demonstrate that inhibition of mitochondrial translation is an effective approach to overcoming venetoclax resistance and provide a rationale for combining tedizolid, azacitidine, and venetoclax as a triplet therapy for AML.
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http://dx.doi.org/10.1126/scitranslmed.aax2863DOI Listing
October 2019

Application of CRISPR-Cas9 Screening Technologies to Study Mitochondrial Biology in Healthy and Disease States.

Adv Exp Med Biol 2019 ;1158:269-277

Princess Margaret Cancer Centre, Toronto, ON, Canada.

Mitochondria play a central role in maintaining normal cellular homeostasis as well as contributing to the pathogenesis of numerous disease states. The advent of CRISPR-Cas9 screening technologies has greatly accelerated the study of mitochondrial biology. In this chapter, we review the various CRISPR-Cas9 screening platforms that are currently available and prior studies that leveraged this technology to identify genes involved in mitochondrial biology in both healthy and disease states. In addition, we discuss the challenges associated with current CRISPR-Cas9 platforms and potential solutions to further enhance this promising technology.
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http://dx.doi.org/10.1007/978-981-13-8367-0_15DOI Listing
September 2019

The Mitochondrial Transacylase, Tafazzin, Regulates for AML Stemness by Modulating Intracellular Levels of Phospholipids.

Cell Stem Cell 2019 04 28;24(4):621-636.e16. Epub 2019 Mar 28.

Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.

Tafazzin (TAZ) is a mitochondrial transacylase that remodels the mitochondrial cardiolipin into its mature form. Through a CRISPR screen, we identified TAZ as necessary for the growth and viability of acute myeloid leukemia (AML) cells. Genetic inhibition of TAZ reduced stemness and increased differentiation of AML cells both in vitro and in vivo. In contrast, knockdown of TAZ did not impair normal hematopoiesis under basal conditions. Mechanistically, inhibition of TAZ decreased levels of cardiolipin but also altered global levels of intracellular phospholipids, including phosphatidylserine, which controlled AML stemness and differentiation by modulating toll-like receptor (TLR) signaling.
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http://dx.doi.org/10.1016/j.stem.2019.02.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7137093PMC
April 2019

Possible Predictive Factors for In-hospital Cardiac Arrest in Patients with Cancer: A Retrospective Single Center Study.

Cureus 2018 Jun 18;10(6):e2828. Epub 2018 Jun 18.

Internal Medicine, Monmouth Medical Center, Long Branch, USA.

Background: Despite cancer being the second most common cause of death in the United States, more people are living longer after the diagnosis of cancer than before. Healthcare workers will be treating an increasing number of patients with cancer. Various studies have identified predictors of cardiac arrest in the general population, however, none have been done to identify such factors in cancer patients who form a more vulnerable group with lower survival rate following cardiac arrest.

Methods: We retrospectively analysed charts of all patients with active cancer who experienced in-hospital cardiac arrest (IHCA) and underwent cardio-pulmonary resuscitation (CPR) from January 2015 to December 2017 at our hospital (n=44, group A). We compared this group to 44 consecutive patients with active cancer admitted to the oncology unit who did not experience cardiac arrest (n=44, group B). We excluded patients in remission.

Results: Both the groups were comparable in terms of age (69 ± 14 vs 68 ± 15, p=0.776) and gender distribution (50% vs 56% males, p=0.521). Prevalence of coronary artery disease (CAD) (25% vs 11%, p=0.097), hypertension (68% vs 66%, p=0.821), hyperlipidaemia (34% in both groups, p=1.000), tobacco abuse (18% vs 27%, p=0.308), and diabetes mellitus (34% vs 23%, p=0.237) was not significantly different between the two groups. Group with cardiac arrest had significantly higher alanine aminotransferase (100 U/L ± 150 vs 47 U/L ± 87, p=0.043), alkaline phosphatase (288 U/L ± 512 vs 118 U/L ± 80, p=0.032), creatinine (1.8 mg/dl ± 1.74 vs 1.1 mg/dl ± 0.76, p=0.023), international normalised ratio (INR) (2.1 ± 1.5 vs 1.2 ± 0.5, p=0.005), and lower estimated -glomerular filtration rate (43 mL/min/1.73m ± 17 vs 51 mL/min/1.73m ± 15, p=0.022) on admission. Group A also had significantly higher incidence of sepsis during the hospital course as compared to group B (30% vs 2%, p<0.001). In group A, 11.4% survived to discharge as compared to 95.5% in group B. Significantly higher number of patients in group B were taking chemotherapy (77.27% vs 34.09%, p=0.000046) and radiation therapy (65.9% vs 22.72%, p=0.000046) as compared to group A.

Conclusion: Cancer patients who experienced IHCA had worse renal and hepatic function; they were frequently diagnosed with sepsis and had similar cardiovascular risk factors as compared to cancer patients who did not experience cardiac arrest. Furthermore, a higher number of patients with active cancer who did not experience cardiac arrest were on chemotherapy, immunotherapy or radiation therapy.
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http://dx.doi.org/10.7759/cureus.2828DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6101448PMC
June 2018

Cardiovascular effects of Hodgkin's lymphoma: a review of literature.

J Cancer Res Clin Oncol 2018 Jan 18;144(1):99-107. Epub 2017 Dec 18.

Monmouth Medical Center, 300, 2nd Ave, Long Branch, NJ, 07740, USA.

Hodgkin's lymphoma (HL) constitutes 0.6% of all the cancers diagnosed worldwide and 10% of all lymphomas. Ten-year survival rate for HL is estimated to be 80% and cardiovascular death is the prevalent cause for a non-malignant death among these HL survivors. We are reviewing the cardiovascular morbidities associated with Hodgkin's lymphoma from the available literature. We performed a systematic review of all articles published from January 1, 1960 to October 1, 2016 on the MEDLINE database using PubMed search engine. Key factors in the diagnosis and management of these conditions are discussed in individual sections.
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http://dx.doi.org/10.1007/s00432-017-2560-xDOI Listing
January 2018

Advancements in the design and scalable production of viral gene transfer vectors.

Biotechnol Bioeng 2018 Jan 30;115(1):25-40. Epub 2017 Oct 30.

Department of Bioengineering, McGill University, Montreal, Quebec, Canada.

The last 10 years have seen a rapid expansion in the use of viral gene transfer vectors, with approved therapies and late stage clinical trials underway for the treatment of genetic disorders, and multiple forms of cancer, as well as prevention of infectious diseases through vaccination. With this increased interest and widespread adoption of viral vectors by clinicians and biopharmaceutical industries, there is an imperative to engineer safer and more efficacious vectors, and develop robust, scalable and cost-effective production platforms for industrialization. This review will focus on major innovations in viral vector design and production systems for three of the most widely used viral vectors: Adenovirus, Adeno-Associated Virus, and Lentivirus.
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http://dx.doi.org/10.1002/bit.26461DOI Listing
January 2018

Activation of the Chicken Anemia Virus Apoptin Protein by Chk1/2 Phosphorylation Is Required for Apoptotic Activity and Efficient Viral Replication.

J Virol 2016 10 29;90(20):9433-45. Epub 2016 Sep 29.

Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada Department of Biochemistry, McGill University, Montréal, QC, Canada Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada

Unlabelled: Chicken anemia virus (CAV) is a single-stranded circular DNA virus that carries 3 genes, the most studied of which is the gene encoding VP3, also known as apoptin. This protein has been demonstrated to specifically kill transformed cells while leaving normal cells unharmed in a manner that is independent of p53 status. Although the mechanistic basis for this differential activity is unclear, it is evident that the subcellular localization of the protein is important for the difference. In normal cells, apoptin exists in filamentous networks in the cytoplasm, whereas in transformed cells, apoptin is present in the nucleus and appears as distinct foci. We have previously demonstrated that DNA damage signaling through the ataxia telangiectasia mutated (ATM) pathway induces the translocation of apoptin from the cytoplasm to the nucleus, where it induces apoptosis. We found that apoptin contains four checkpoint kinase consensus sites and that mutation of either threonine 56 or 61 to alanine restricts apoptin to the cytoplasm. Furthermore, treatment of tumor cells expressing apoptin with inhibitors of checkpoint kinase 1 (Chk1) and Chk2 causes apoptin to localize to the cytoplasm. Importantly, silencing of Chk2 rescues cancer cells from the cytotoxic effects of apoptin. Finally, treatment of virus-producing cells with Chk inhibitor protects them from virus-mediated toxicity and reduces the titer of progeny virus. Taken together, our results indicate that apoptin is a sensor of DNA damage signaling through the ATM-Chk2 pathway, which induces it to migrate to the nucleus during viral replication.

Importance: The chicken anemia virus (CAV) protein apoptin is known to induce tumor cell-specific death when expressed. Therefore, understanding its regulation and mechanism of action could provide new insights into tumor cell biology. We have determined that checkpoint kinase 1 and 2 signaling is important for apoptin regulation and is a likely feature of both tumor cells and host cells producing virus progeny. Inhibition of checkpoint signaling prevents apoptin toxicity in tumor cells and attenuates CAV replication, suggesting it may be a future target for antiviral therapy.
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http://dx.doi.org/10.1128/JVI.00936-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5044837PMC
October 2016

Persistent Hypoglycemia in Patient with Hodgkin's Disease.

Case Rep Oncol Med 2015 29;2015:820286. Epub 2015 Dec 29.

Department of Internal Medicine, Monmouth Medical Center, Long Branch, NJ 07740, USA; Section of Hematology and Oncology, Monmouth Medical Center, Long Branch, NJ 07740, USA.

Hypoglycemia is a rare complication of Hodgkin's disease. Several explanations have been postulated but the exact pathophysiology is not well understood. We are presenting a case of newly diagnosed Stage IV Hodgkin's disease that developed persistent and recurrent hypoglycemia despite giving glucagon, repeated 50% dextrose, and D5 and D10 continuous infusion. Hypoglycemia workup showed the C-peptide level to be low. Patient was suspected of having hypoglycemia related to lymphoma and was given a trial of prednisone which resolved the hypoglycemic episodes and made the patient euglycemic for the rest of his hospital stay. The presence of a substance that mimicked the effects of insulin was highly suspected. Several case reports strengthen the hypothesis of an insulin-like growth factor or antibodies secreted by the cancer cells causing hypoglycemia in Hodgkin's disease but none of them have been confirmed. Further investigation is warranted to more clearly define the pathophysiology of persistent hypoglycemia in patients with Hodgkin's disease.
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http://dx.doi.org/10.1155/2015/820286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4709603PMC
February 2016

Pericentriolar Targeting of the Mouse Mammary Tumor Virus GAG Protein.

PLoS One 2015 29;10(6):e0131515. Epub 2015 Jun 29.

Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.

The Gag protein of the mouse mammary tumor virus (MMTV) is the chief determinant of subcellular targeting. Electron microscopy studies show that MMTV Gag forms capsids within the cytoplasm and assembles as immature particles with MMTV RNA and the Y box binding protein-1, required for centrosome maturation. Other betaretroviruses, such as Mason-Pfizer monkey retrovirus (M-PMV), assemble adjacent to the pericentriolar region because of a cytoplasmic targeting and retention signal in the Matrix protein. Previous studies suggest that the MMTV Matrix protein may also harbor a similar cytoplasmic targeting and retention signal. Herein, we show that a substantial fraction of MMTV Gag localizes to the pericentriolar region. This was observed in HEK293T, HeLa human cell lines and the mouse derived NMuMG mammary gland cells. Moreover, MMTV capsids were observed adjacent to centrioles when expressed from plasmids encoding either MMTV Gag alone, Gag-Pro-Pol or full-length virus. We found that the cytoplasmic targeting and retention signal in the MMTV Matrix protein was sufficient for pericentriolar targeting, whereas mutation of the glutamine to alanine at position 56 (D56/A) resulted in plasma membrane localization, similar to previous observations from mutational studies of M-PMV Gag. Furthermore, transmission electron microscopy studies showed that MMTV capsids accumulate around centrioles suggesting that, similar to M-PMV, the pericentriolar region may be a site for MMTV assembly. Together, the data imply that MMTV Gag targets the pericentriolar region as a result of the MMTV cytoplasmic targeting and retention signal, possibly aided by the Y box protein-1 required for the assembly of centrosomal microtubules.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131515PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4486188PMC
March 2016

Mediastinal B-cell lymphoma presenting with jugular-subclavian deep vein thrombosis as the first presentation.

Case Rep Vasc Med 2015 4;2015:929127. Epub 2015 Mar 4.

Department of Internal Medicine, Monmouth Medical Center, Long Branch, NJ 07740, USA ; Department of Oncological Medicine, Monmouth Medical Center, Long Branch, NJ 07740, USA.

Jugular venous thrombosis infrequently could be secondary to malignancy and has seldom been reported secondary to mediastinal large B-cell lymphomas. The postulated mechanisms are mechanical compression that leads to stagnation of blood in the venous system of the neck and/or an increase in the circulating thrombogenic elements that could cause venous thromboembolism as a paraneoplastic phenomenon. We report the case of a middle aged male presenting with right sided neck pain and arm swelling secondary to ipsilateral jugular-subclavian deep vein thrombosis. Investigations revealed it to be secondary to a mediastinal mass shown on CT scan of the chest.
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http://dx.doi.org/10.1155/2015/929127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4364112PMC
March 2015

Role of novel retroviruses in chronic liver disease: assessing the link of human betaretrovirus with primary biliary cirrhosis.

Curr Infect Dis Rep 2015 Feb;17(2):460

Department of Medicine, University of Alberta, Edmonton, AB, Canada.

A human betaretrovirus resembling mouse mammary tumor virus has been characterized in patients with primary biliary cirrhosis. The agent triggers a disease-specific phenotype in vitro with aberrant cell-surface expression of mitochondrial antigens. The presentation of a usually sequestered self-protein is thought to lead to the loss of tolerance and the production of anti-mitochondrial antibodies associated with the disease. Similar observations have been made in mouse models, where mouse mammary tumor virus infection has been linked with the development of cholangitis and production of anti-mitochondrial antibodies. The use of combination antiretroviral therapy has been shown to impact on histological and biochemical disease in mouse models of autoimmune biliary disease and in clinical trials of patients with primary biliary cirrhosis. However, the HIV protease inhibitors are not well tolerated in patients with primary biliary cirrhosis, and more efficacious regimens will be required to clearly link reduction of viral load with improvement of cholangitis.
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http://dx.doi.org/10.1007/s11908-014-0460-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4353873PMC
February 2015

Metastatic malignant melanoma of the inguinal lymph node with unknown primary lesion.

Case Rep Med 2015 1;2015:879460. Epub 2015 Feb 1.

Department of Oncology, Monmouth Medical Center, Long Branch, NJ 07740, USA.

Background. Malignant melanoma could present with metastasis with unknown primary (MUP) and this happens in 2-3% according to the studies. Around 90% of melanomas have cutaneous origin, but still there are melanomas that could be found in visceral organs or lymph nodes with unknown primary site. Spontaneous regression of the primary site could be an explanation. Case Report. We report a 58-year-old Caucasian male who presented with a right sided swelling in the inguinal region. Surgery was performed and biopsy showed metastatic malignant melanoma. No cutaneous lesions were identified by history or physical examination. Work up could not detect the primary lesion and patient was started on radiotherapy and immunotherapy. Conclusion. We present a case of malignant melanoma of unknown primary presenting in an unusual place which is the inguinal lymph node. Theories try to explain the pathway of development of such tumors and one of the theories mentions that it could be a spontaneous regression of the primary cutaneous lesion. Another theory is that it could be from transformation of aberrant melanocyte within the lymph node. Prognosis is postulated to be better in this case than in melanoma with a known primary.
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http://dx.doi.org/10.1155/2015/879460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4331473PMC
February 2015

Impact of combination antiretroviral therapy in the NOD.c3c4 mouse model of autoimmune biliary disease.

Liver Int 2015 Apr 31;35(4):1442-50. Epub 2014 Oct 31.

Department of Medicine, University of Alberta, Edmonton, AB, Canada.

Background & Aims: The NOD.c3c4 mouse model develops autoimmune biliary disease characterized by spontaneous granulomatous cholangitis, antimitochondrial antibodies and liver failure. This model for primary biliary cirrhosis (PBC) has evidence of biliary infection with mouse mammary tumour virus (MMTV), suggesting that the virus may have a role in cholangitis development and progression of liver disease in this mouse model. We tested the hypothesis that MMTV infection is associated with cholangitis in the NOD.c3c4 mouse model by investigating whether antiretroviral therapy impacts on viral levels and liver disease.

Methods: NOD.c3c4 mice were treated with combination antiretroviral therapy. Response to treatment was studied by measuring MMTV RNA in the liver, liver enzyme levels in serum and liver histology using a modified Ishak score.

Results: Combination therapy with the reverse transcriptase inhibitors, tenofovir and emtricitabine, resulted in a significant reduction in serum liver enzyme levels, attenuation of cholangitis and decreased MMTV levels in the livers of NOD.c3c4 mice. Furthermore, treatment with the retroviral protease inhibitors, lopinavir and ritonavir, in addition to the reverse transcriptase inhibitors, resulted in further decrease in MMTV levels and attenuation of liver disease in this model.

Conclusions: The attenuation of cholangitis with regimens containing the reverse transcriptase inhibitors, tenofovir and emtricitabine, and the protease inhibitors, lopinavir and ritonavir, suggests that retroviral infection may play a role in the development of cholangitis in this model.
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http://dx.doi.org/10.1111/liv.12699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4403978PMC
April 2015

2-aminopurine enhances the oncolytic activity of an E1b-deleted adenovirus in hepatocellular carcinoma cells.

PLoS One 2013 4;8(6):e65222. Epub 2013 Jun 4.

Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.

Adenoviruses with deletions of viral genes have been extensively studied as potential cancer therapeutics. Although a high degree of cancer selectivity has been demonstrated with these conditionally replicating adenoviruses, low levels of virus replication can be detected in normal cells. Furthermore, these mutations were also found to reduce the activity of the replicating viruses in certain cancer cells. Recent studies have shown that co-administration of chemotherapeutic drugs may increase the activity of these viruses without affecting their specificity. We constructed an adenovirus with deletions of both the E1b and the VA-RNA genes and found that replication of this virus was selective for human hepatocellular carcinoma (HCC) cell lines when compared to normal cell lines. Furthermore, we show that 2-aminopurine (2'AP) treatment selectively enhanced virus replication and virus-mediated death of HCC cells. 2'AP did not compensate for the loss of VA-RNA activities, but rather the loss of an E1b-55K activity, such as the DNA damage response, suggesting that co-administration of 2'AP derivatives that block host DNA damage response, may increase the oncolytic activity of AdΔE1bΔVA without reducing its selectivity for HCC cells.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065222PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3672087PMC
September 2014

The expression and oncogenic effects of the embryonic stem cell marker SALL4 in ALK-positive anaplastic large cell lymphoma.

Cell Signal 2012 Oct 26;24(10):1955-63. Epub 2012 Jun 26.

Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Canada.

SALL4 is one of the master transcriptional factors that are crucial in maintaining the pluripotency of embryonic stem cells (ESCs). While the expression of SALL4 is normally restricted to ESCs and somatic stem cells, we found that it is aberrantly expressed in ALK-positive anaplastic large cell lymphoma (ALK+ ALCL), a type of lymphoid malignancy carrying a mature T-cell immunophenotype. shRNA knockdown of SALL4 in ALK+ ALCL cell lines resulted in apoptosis and cell-cycle arrest, and significantly decreased colony formation on soft agar. These changes correlated with the downregulation of several anti-apoptotic proteins and facilitators of cell-cycle progression. Based on the differential response to a SALL4 reporter construct, we were able to separate two distinct cell subsets in Karpas 299 (an ALK+ ALCL cell line), namely SALL4(high) and SALL4(low). Importantly, the biological effects induced by SALL4 knock-down in Karpas 299 were restricted to the purified SALL4(high) cells, and this finding further supports the concept that SALL4 is biologically important in ALK+ ALCL. Lastly, the expression of SALL4 was not dependent on the nucleophosmin (NPM)-anaplastic lymphoma kinase (ALK)/STAT3 signaling axis, the key oncogenic driver in ALK+ ALCL. To conclude, for the first time, our study has revealed the oncogenic contributions of an ESC protein in the pathogenesis of ALK+ ALCL.
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http://dx.doi.org/10.1016/j.cellsig.2012.06.005DOI Listing
October 2012

EscA is a crucial component of the type III secretion system of enteropathogenic Escherichia coli.

J Bacteriol 2012 Jun 23;194(11):2819-28. Epub 2012 Mar 23.

Michael Smith Laboratories, Vancouver, British Columbia, Canada.

The virulence of many Gram-negative pathogens is associated with type III secretion systems (T3SSs), which deliver virulence effector proteins into the cytoplasm of host cells. Components of enteropathogenic Escherichia coli (EPEC) T3SS are encoded within the locus of enterocyte effacement (LEE). While most LEE-encoded T3SS proteins in EPEC have assigned names and functions, a few of them remain poorly characterized. Here, we studied a small LEE-encoded protein, Orf15, that shows no homology to other T3SS/flagellar proteins and is only present in attaching and effacing pathogens, including enterohemorrhagic E. coli and Citrobacter rodentium. Our findings demonstrated that it is essential for type III secretion (T3S) and that it is localized to the periplasm and associated with the inner membrane. Membrane association was driven by the N-terminal 19 amino acid residues, which were also shown to be essential for T3S. Consistent with its localization, Orf15 was found to interact with the EPEC T3SS outer membrane ring component, EscC, which was previously shown to be embedded within the outer membrane and protruding into the periplasmic space. Interestingly, we found that the predicted coiled-coil structure of Orf15 is critical for the protein's function. Overall, our findings suggest that Orf15 is a structural protein that contributes to the structural integrity of the T3S complex, and therefore we propose to rename it EscA.
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http://dx.doi.org/10.1128/JB.00103-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370638PMC
June 2012

Aberrant expression of the transcriptional factor Twist1 promotes invasiveness in ALK-positive anaplastic large cell lymphoma.

Cell Signal 2012 Apr 8;24(4):852-8. Epub 2011 Dec 8.

Department of Surgery, University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada; Department of Medical Oncology, The First Hospital of China Medical University, Shen Yang 110001, PR China.

The transcriptional factor Twist1 has been shown to play a key role in regulating epithelial mesenchymal transition, invasiveness and migratory properties in solid tumors. We found that Twist1 is aberrantly expressed in ALK-positive anaplastic large cell lymphoma (ALK+ALCL), a type of T-cell lymphoid malignancy. Using RT-PCR and Western blots, Twist1 was detectable in all 3 ALK+ALCL cell lines examined but absent in normal T-cells. By immunohistochemistry, Twist1 was detectable in all 10 cases of ALK+ALCL examined; benign lymphoid tissues were consistently negative. Twist1 expression in ALK+ALCL cells can be attributed to the NPM-ALK/STAT3 signaling axis, the key oncogenic driving force in this tumor type. Twist1 is biologically important in ALK+ALCL cells, as Twist1 knockdown resulted in a significant decrease in their invasiveness in an in-vitro assay. Further investigation revealed that this increase in invasiveness is linked to the activation of AKT and down-regulation of p66Shc, two signaling proteins known to be involved in NPM-ALK-mediated oncogenesis. Lastly, knockdown of Twist1 sensitizes ALK+ALCL cells to the growth inhibitory effect of PF-2341066 (Crizotinib®), an ALK inhibitor being used in clinical trials. In conclusion, Twist1 expression, owing to the abnormal NPM-ALK/STAT3 signaling, contributes to its invasiveness and decreased sensitivity to PF-2341066 in ALK+ALCL.
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http://dx.doi.org/10.1016/j.cellsig.2011.11.020DOI Listing
April 2012

Lenalidomide and rituximab in Waldenstrom's macroglobulinemia.

Clin Cancer Res 2009 Jan;15(1):355-60

Bing Center for Waldenstrom's Macroglobulinemia, Dana-Farber Cancer Institute, Boston, MA 02115, USA.

Purpose: Thalidomide and its more potent immunomodulatory derivative lenalidomide enhance rituximab-mediated antibody-dependent cell-mediated cytotoxicity. We therefore evaluated lenalidomide and rituximab in symptomatic Waldenstrom's macroglobulinemia (WM) patients naive to either agent.

Experimental Design: Intended therapy consisted of 48 weeks of lenalidomide (25 mg/d for 3 weeks and then 1 week off) along with rituximab (375 mg/m(2)/wk) dosed on weeks 2 to 5 and 13 to 16. Sixteen patients were enrolled, 12 of whom were previously untreated.

Results: Unexpectedly, we observed an acute decrease in hematocrit in 13 of 16 patients (median hematocrit decrease, 4.8%), which was attributable to lenalidomide patients and which led to cessation of further enrollment on this study. Lenalidomide-related anemia was observed even at doses as low as 5 mg/d and occurred in the absence of hemolysis or other cytopenias. The overall response and major response (<50% decrease in serum IgM) rates were 50% and 25%, respectively, on an intent-to-treat basis. With a median follow-up of 31.3 months, 4 of 8 responding patients have progressed with a median time to progression of 18.9 months.

Conclusion: Lenalidomide produces unexpected but clinically significant acute anemia in patients with WM. In comparison with our previous study with thalidomide and rituximab in an analogous patient population, the responses achieved in WM patients with lenalidomide and rituximab appear less favorable.
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http://dx.doi.org/10.1158/1078-0432.CCR-08-0862DOI Listing
January 2009

Multicenter clinical trial of bortezomib in relapsed/refractory Waldenstrom's macroglobulinemia: results of WMCTG Trial 03-248.

Clin Cancer Res 2007 Jun;13(11):3320-5

Bing Center for Waldenstrom's Macroglobulinemia, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.

Purpose: Waldenstrom's macroglobulinemia (WM) is a B-cell disorder. Despite advances in the therapy, WM remains incurable. As such, novel therapeutic agents are needed for the treatment of WM.

Experimental Design: In this multicenter study, 27 patients with WM received up to eight cycles of bortezomib at 1.3 mg/m(2) on days 1, 4, 8, and 11. All but one patient had relapsed/or refractory disease.

Results: Following therapy, median serum IgM levels declined from 4,660 to 2,092 mg/dL (P < 0.0001). The overall response rate was 85%, with 10 and 13 patients achieving minor and major responses, respectively. Responses were prompt and occurred at median of 1.4 months. The median time to progression for all responding patients was 7.9 (range, 3-21.4+) months. The most common grade III/IV toxicities occurring in > or =5% of patients were sensory neuropathies (22.2%), leukopenia (18.5%), neutropenia (14.8%), dizziness (11.1%), and thrombocytopenia (7.4%). Sensory neuropathies resolved or improved in nearly all patients following cessation of therapy.

Conclusions: The results of these studies show that bortezomib is an active agent in relapsed and refractory WM.
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http://dx.doi.org/10.1158/1078-0432.CCR-06-2511DOI Listing
June 2007
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