Publications by authors named "Jennifer Totonchy"

18 Publications

  • Page 1 of 1

SARS-CoV-2 early infection signature identified potential key infection mechanisms and drug targets.

BMC Genomics 2021 Feb 18;22(1):125. Epub 2021 Feb 18.

School of Pharmacy, Chapman University, Irvine, CA, 92618, USA.

Background: The ongoing COVID-19 outbreak has caused devastating mortality and posed a significant threat to public health worldwide. Despite the severity of this illness and 2.3 million worldwide deaths, the disease mechanism is mostly unknown. Previous studies that characterized differential gene expression due to SARS-CoV-2 infection lacked robust validation. Although vaccines are  now available, effective treatment options are still out of reach.

Results: To characterize the transcriptional activity of SARS-CoV-2 infection, a gene signature consisting of 25 genes was generated using a publicly available RNA-Sequencing (RNA-Seq) dataset of cultured cells infected with SARS-CoV-2. The signature estimated infection level accurately in bronchoalveolar lavage fluid (BALF) cells and peripheral blood mononuclear cells (PBMCs) from healthy and infected patients (mean 0.001 vs. 0.958; P < 0.0001). These signature genes were investigated in their ability to distinguish the severity of SARS-CoV-2 infection in a single-cell RNA-Sequencing dataset. TNFAIP3, PPP1R15A, NFKBIA, and IFIT2 had shown bimodal gene expression in various immune cells from severely infected patients compared to healthy or moderate infection cases. Finally, this signature was assessed using the publicly available ConnectivityMap database to identify potential disease mechanisms and drug repurposing candidates. Pharmacological classes of tricyclic antidepressants, SRC-inhibitors, HDAC inhibitors, MEK inhibitors, and drugs such as atorvastatin, ibuprofen, and ketoconazole showed strong negative associations (connectivity score < - 90), highlighting the need for further evaluation of these candidates for their efficacy in treating SARS-CoV-2 infection.

Conclusions: Thus, using the 25-gene SARS-CoV-2 infection signature, the SARS-CoV-2 infection status was captured in BALF cells, PBMCs and postmortem lung biopsies. In addition, candidate SARS-CoV-2 therapies with known safety profiles were identified. The signature genes could potentially also be used to characterize the COVID-19 disease severity in patients' expression profiles of BALF cells.
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http://dx.doi.org/10.1186/s12864-021-07433-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889713PMC
February 2021

Differential modulation of SK channel subtypes by phosphorylation.

Cell Calcium 2021 03 6;94:102346. Epub 2021 Jan 6.

Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA. Electronic address:

Small-conductance Ca-activated K (SK) channels are voltage-independent and are activated by Ca binding to the calmodulin constitutively associated with the channels. Both the pore-forming subunits and the associated calmodulin are subject to phosphorylation. Here, we investigated the modulation of different SK channel subtypes by phosphorylation, using the cultured endothelial cells as a tool. We report that casein kinase 2 (CK2) negatively modulates the apparent Ca sensitivity of SK1 and IK channel subtypes by more than 5-fold, whereas the apparent Ca sensitivity of the SK3 and SK2 subtypes is only reduced by ∼2-fold, when heterologously expressed on the plasma membrane of cultured endothelial cells. The SK2 channel subtype exhibits limited cell surface expression in these cells, partly as a result of the phosphorylation of its C-terminus by cyclic AMP-dependent protein kinase (PKA). SK2 channels expressed on the ER and mitochondria membranes may protect against cell death. This work reveals the subtype-specific modulation of the apparent Ca sensitivity and subcellular localization of SK channels by phosphorylation in cultured endothelial cells.
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http://dx.doi.org/10.1016/j.ceca.2020.102346DOI Listing
March 2021

Molecular Virology of KSHV in the Lymphocyte Compartment-Insights From Patient Samples and Infection Models.

Front Cell Infect Microbiol 2020 4;10:607663. Epub 2020 Dec 4.

Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, United States.

The incidence of Kaposi's sarcoma-associated herpesvirus (KSHV)-associated Kaposi Sarcoma has declined precipitously in the present era of effective HIV treatment. However, KSHV-associated lymphoproliferative disorders although rare, have not seen a similar decline. Lymphoma is now a leading cause of death in people living with HIV (PLWH), indicating that the immune reconstitution provided by antiretroviral therapy is not sufficient to fully correct the lymphomagenic immune dysregulation perpetrated by HIV infection. As such, novel insights into the mechanisms of KSHV-mediated pathogenesis in the immune compartment are urgently needed in order to develop novel therapeutics aimed at prevention and treatment of KSHV-associated lymphoproliferations. In this review, we will discuss our current understanding of KSHV molecular virology in the lymphocyte compartment, concentrating on studies which explore mechanisms unique to infection in B lymphocytes.
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http://dx.doi.org/10.3389/fcimb.2020.607663DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7746649PMC
December 2020

An Update of the Virion Proteome of Kaposi Sarcoma-Associated Herpesvirus.

Viruses 2020 12 2;12(12). Epub 2020 Dec 2.

Biomedical and Pharmaceutical Sciences Department, Chapman University School of Pharmacy, Irvine, CA 92618, USA.

The virion proteins of Kaposi sarcoma-associated herpesvirus (KSHV) were initially characterized in 2005 in two separate studies that combined the detection of 24 viral proteins and a few cellular components via LC-MS/MS or MALDI-TOF. Despite considerable advances in the sensitivity and specificity of mass spectrometry instrumentation in recent years, leading to significantly higher yields in detections, the KSHV virion proteome has not been revisited. In this study, we have re-examined the protein composition of purified KSHV virions via ultra-high resolution Qq time-of-flight mass spectrometry (UHR-QqTOF). Our results confirm the detection of all previously reported virion proteins, in addition to 17 other viral proteins, some of which have been characterized as virion-associated using other methods, and 10 novel proteins identified as virion-associated for the first time in this study. These results add KSHV ORF9, ORF23, ORF35, ORF48, ORF58, ORF72/vCyclin, K3, K9/vIRF1, K10/vIRF4, and K10.5/vIRF3 to the list of KSHV proteins that can be incorporated into virions. The addition of these proteins to the KSHV virion proteome provides novel and important insight into early events in KSHV infection mediated by virion-associated proteins. Data are available via ProteomeXchange with identifier PXD022626.
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http://dx.doi.org/10.3390/v12121382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7761624PMC
December 2020

Analysis of KSHV B lymphocyte lineage tropism in human tonsil reveals efficient infection of CD138+ plasma cells.

PLoS Pathog 2020 10 19;16(10):e1008968. Epub 2020 Oct 19.

School of Pharmacy, Chapman University, Irvine, California, United States of America.

Despite 25 years of research, the basic virology of Kaposi Sarcoma Herpesviruses (KSHV) in B lymphocytes remains poorly understood. This study seeks to fill critical gaps in our understanding by characterizing the B lymphocyte lineage-specific tropism of KSHV. Here, we use lymphocytes derived from 40 human tonsil specimens to determine the B lymphocyte lineages targeted by KSHV early during de novo infection in our ex vivo model system. We characterize the immunological diversity of our tonsil specimens and determine that overall susceptibility of tonsil lymphocytes to KSHV infection varies substantially between donors. We demonstrate that a variety of B lymphocyte subtypes are susceptible to KSHV infection and identify CD138+ plasma cells as a highly targeted cell type for de novo KSHV infection. We determine that infection of tonsil B cell lineages is primarily latent with few lineages contributing to lytic replication. We explore the use of CD138 and heparin sulfate proteoglycans as attachment factors for the infection of B lymphocytes and conclude that they do not play a substantial role. Finally, we determine that the host T cell microenvironment influences the course of de novo infection in B lymphocytes. These results improve our understanding of KSHV transmission and the biology of early KSHV infection in a naïve human host, and lay a foundation for further characterization of KSHV molecular virology in B lymphocyte lineages.
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http://dx.doi.org/10.1371/journal.ppat.1008968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7595638PMC
October 2020

Cytokine-Targeted Therapeutics for KSHV-Associated Disease.

Viruses 2020 09 28;12(10). Epub 2020 Sep 28.

Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA.

Kaposi's sarcoma-associated herpesvirus (KSHV) also known as human herpesvirus 8 (HHV-8), is linked to several human malignancies including Kaposi sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman's disease (MCD) and recently KSHV inflammatory cytokine syndrome (KICS). As with other diseases that have a significant inflammatory component, current therapy for KSHV-associated disease is associated with significant off-target effects. However, recent advances in our understanding of the pathogenesis of KSHV have produced new insight into the use of cytokines as potential therapeutic targets. Better understanding of the role of cytokines during KSHV infection and tumorigenesis may lead to new preventive or therapeutic strategies to limit KSHV spread and improve clinical outcomes. The cytokines that appear to be promising candidates as KSHV antiviral therapies include interleukins 6, 10, and 12 as well as interferons and tumor necrosis factor-family cytokines. This review explores our current understanding of the roles that cytokines play in promoting KSHV infection and tumorigenesis, and summarizes the current use of cytokines as therapeutic targets in KSHV-associated diseases.
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http://dx.doi.org/10.3390/v12101097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600567PMC
September 2020

A multivalent Kaposi sarcoma-associated herpesvirus-like particle vaccine capable of eliciting high titers of neutralizing antibodies in immunized rabbits.

Vaccine 2019 07 11;37(30):4184-4194. Epub 2019 Jun 11.

Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, CA, United States. Electronic address:

Kaposi sarcoma-associated herpesvirus (KSHV) is an emerging pathogen and the causative agent of multiple cancers in immunocompromised patients. To date, there is no licensed prophylactic KSHV vaccine. In this study, we generated a novel subunit vaccine that incorporates four key KSHV envelope glycoproteins required for viral entry in diverse cell types (gpK8.1, gB, and gH/gL) into a single multivalent KSHV-like particle (KSHV-LP). Purified KSHV-LPs were similar in size, shape, and morphology to KSHV virions. Vaccination of rabbits with adjuvanted KSHV-LPs generated strong glycoprotein-specific antibody responses, and purified immunoglobulins from KSHV-LP-immunized rabbits neutralized KSHV infection in epithelial, endothelial, fibroblast, and B cell lines (60-90% at the highest concentration tested). These findings suggest that KSHV-LPs may be an ideal platform for developing a safe and effective prophylactic KSHV vaccine. We envision performing future studies in animal models that are susceptible to KSHV infection, to determine correlates of immune protection in vivo.
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http://dx.doi.org/10.1016/j.vaccine.2019.04.071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6876619PMC
July 2019

Kaposi Sarcoma-Associated Herpesvirus Glycoprotein H Is Indispensable for Infection of Epithelial, Endothelial, and Fibroblast Cell Types.

J Virol 2019 08 30;93(16). Epub 2019 Jul 30.

Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA

Kaposi sarcoma-associated herpesvirus (KSHV) is an emerging pathogen and is the causative infectious agent of Kaposi sarcoma and two malignancies of B cell origin. To date, there is no licensed KSHV vaccine. Development of an effective vaccine against KSHV continues to be limited by a poor understanding of how the virus initiates acute primary infection in diverse human cell types. The role of glycoprotein H (gH) in herpesvirus entry mechanisms remains largely unresolved. To characterize the requirement for KSHV gH in the viral life cycle and in determination of cell tropism, we generated and characterized a mutant KSHV in which expression of gH was abrogated. Using a bacterial artificial chromosome containing a complete recombinant KSHV genome and recombinant DNA technology, we inserted stop codons into the gH coding region. We used electron microscopy to reveal that the gH-null mutant virus assembled and exited from cells normally, compared to wild-type virus. Using purified virions, we assessed infectivity of the gH-null mutant in diverse mammalian cell types Unlike wild-type virus or a gH-containing revertant, the gH-null mutant was unable to infect any of the epithelial, endothelial, or fibroblast cell types tested. However, its ability to infect B cells was equivocal and remains to be investigated due to generally poor infectivity Together, these results suggest that gH is critical for KSHV infection of highly permissive cell types, including epithelial, endothelial, and fibroblast cells. All homologues of herpesvirus gH studied to date have been implicated in playing an essential role in viral infection of diverse permissive cell types. However, the role of gH in the mechanism of KSHV infection remains largely unresolved. In this study, we generated a gH-null mutant KSHV and provided evidence that deficiency of gH expression did not affect viral particle assembly or egress. Using the gH-null mutant, we showed that gH was indispensable for KSHV infection of epithelial, endothelial, and fibroblast cells This suggests that gH is an important target for the development of a KSHV prophylactic vaccine to prevent initial viral infection.
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http://dx.doi.org/10.1128/JVI.00630-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6675886PMC
August 2019

Src Family Kinase Inhibitors Block Translation of Alphavirus Subgenomic mRNAs.

Antimicrob Agents Chemother 2019 04 27;63(4). Epub 2019 Mar 27.

Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon, USA

Alphaviruses are arthropod-transmitted RNA viruses that can cause arthralgia, myalgia, and encephalitis in humans. Since the role of cellular kinases in alphavirus replication is unknown, we profiled kinetic changes in host kinase abundance and phosphorylation following chikungunya virus (CHIKV) infection of fibroblasts. Based upon the results of this study, we treated CHIKV-infected cells with kinase inhibitors targeting the Src family kinase (SFK)-phosphatidylinositol 3-kinase (PI3K)-AKT-mTORC signaling pathways. Treatment of cells with SFK inhibitors blocked the replication of CHIKV as well as multiple other alphaviruses, including Mayaro virus, O'nyong-nyong virus, Ross River virus, and Venezuelan equine encephalitis virus. Dissecting the effect of SFK inhibition on alphavirus replication, we found that viral structural protein levels were significantly reduced, but synthesis of viral genomic and subgenomic RNAs was unaffected. By measuring the association of viral RNA with polyribosomes, we found that the SFK inhibitor dasatinib blocks alphavirus subgenomic RNA translation. Our results demonstrate a role for SFK signaling in alphavirus subgenomic RNA translation and replication. Targeting host factors involved in alphavirus replication represents an innovative, perhaps paradigm-shifting, strategy for exploring the replication of CHIKV and other alphaviruses while promoting antiviral therapeutic development.
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http://dx.doi.org/10.1128/AAC.02325-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6496153PMC
April 2019

KSHV induces immunoglobulin rearrangements in mature B lymphocytes.

PLoS Pathog 2018 04 16;14(4):e1006967. Epub 2018 Apr 16.

Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, United States of Amercia.

Kaposi sarcoma herpesvirus (KSHV/HHV-8) is a B cell tropic human pathogen, which is present in vivo in monotypic immunoglobulin λ (Igλ) light chain but polyclonal B cells. In the current study, we use cell sorting to infect specific B cell lineages from human tonsil specimens in order to examine the immunophenotypic alterations associated with KSHV infection. We describe IL-6 dependent maturation of naïve B lymphocytes in response to KSHV infection and determine that the Igλ monotypic bias of KSHV infection in vivo is due to viral induction of BCR revision. Infection of immunoglobulin κ (Igκ) naïve B cells induces expression of Igλ and isotypic inclusion, with eventual loss of Igκ. We show that this phenotypic shift occurs via re-induction of Rag-mediated V(D)J recombination. These data explain the selective presence of KSHV in Igλ B cells in vivo and provide the first evidence that a human pathogen can manipulate the molecular mechanisms responsible for immunoglobulin diversity.
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http://dx.doi.org/10.1371/journal.ppat.1006967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5919685PMC
April 2018

Extrafollicular activities: perspectives on HIV infection, germinal center-independent maturation pathways, and KSHV-mediated lymphoproliferation.

Curr Opin Virol 2017 10 3;26:69-73. Epub 2017 Aug 3.

Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, United States. Electronic address:

Early events in the pathogenesis of KSHV-associated lymphoproliferations in the context of HIV disease remain poorly understood. Recent research indicates that latent HIV infection causes persistent immune dysfunction in B cell follicles. Simultaneously, lack of T cell immune surveillance in the lymph nodes dysregulates the biology of EBV. In sum, these defects bias B lymphocyte maturation away from traditional T cell-dependent germinal center-mediated pathways and towards extrafollicular pathways. Recent advances in B lymphocyte immunology suggest that extrafollicular maturation pathways for antibody secreting cells are more flexible and robust than previously believed. These responses are now understood to be both durable and antigen-specific, and even canonically germinal center-restricted events such as class switch recombination and somatic hypermutation have now been demonstrated in an extrafollicular context. As a lymphotrophic pathogen which causes disease primarily in the context of HIV and EBV co-infection, future studies examining the interactions of KSHV biology with extrafollicular B cell maturation pathways will be critical to uncovering key aspects of KSHV-mediated immune pathology.
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http://dx.doi.org/10.1016/j.coviro.2017.07.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673501PMC
October 2017

Inhibition of Hsp90 Suppresses PI3K/AKT/mTOR Signaling and Has Antitumor Activity in Burkitt Lymphoma.

Mol Cancer Ther 2017 09 15;16(9):1779-1790. Epub 2017 Jun 15.

Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, New York.

Hsp90 is a molecular chaperone that protects proteins, including oncogenic signaling complexes, from proteolytic degradation. PU-H71 is a next-generation Hsp90 inhibitor that preferentially targets the functionally distinct pool of Hsp90 present in tumor cells. Tumors that are driven by the MYC oncoprotein may be particularly sensitive to PU-H71 due to the essential role of Hsp90 in the epichaperome, which maintains the malignant phenotype in the setting of MYC. Burkitt lymphoma (BL) is an aggressive B-cell lymphoma characterized by MYC dysregulation. In this study, we evaluated Hsp90 as a potential therapeutic target in BL. We found that primary BL tumors overexpress Hsp90 and that Hsp90 inhibition has antitumor activity and , including potent activity in a patient-derived xenograft model of BL. To evaluate the targets of PU-H71 in BL, we performed high-affinity capture followed by proteomic analysis using mass spectrometry. We found that Hsp90 inhibition targets multiple components of PI3K/AKT/mTOR signaling, highlighting the importance of this pathway in BL. Finally, we found that the anti-lymphoma activity of PU-H71 is synergistic with dual PI3K/mTOR inhibition and Overall, this work provides support for Hsp90 as a therapeutic target in BL and suggests the potential for combination therapy with PU-H71 and inhibitors of PI3K/mTOR. .
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http://dx.doi.org/10.1158/1535-7163.MCT-16-0848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587381PMC
September 2017

Identification of a nucleoside analog active against adenosine kinase-expressing plasma cell malignancies.

J Clin Invest 2017 Jun 15;127(6):2066-2080. Epub 2017 May 15.

Department of Pathology and Laboratory Medicine.

Primary effusion lymphoma (PEL) is a largely incurable malignancy of B cell origin with plasmacytic differentiation. Here, we report the identification of a highly effective inhibitor of PEL. This compound, 6-ethylthioinosine (6-ETI), is a nucleoside analog with toxicity to PEL in vitro and in vivo, but not to other lymphoma cell lines tested. We developed and performed resistome analysis, an unbiased approach based on RNA sequencing of resistant subclones, to discover the molecular mechanisms of sensitivity. We found different adenosine kinase-inactivating (ADK-inactivating) alterations in all resistant clones and determined that ADK is required to phosphorylate and activate 6-ETI. Further, we observed that 6-ETI induces ATP depletion and cell death accompanied by S phase arrest and DNA damage only in ADK-expressing cells. Immunohistochemistry for ADK served as a biomarker approach to identify 6-ETI-sensitive tumors, which we documented for other lymphoid malignancies with plasmacytic features. Notably, multiple myeloma (MM) expresses high levels of ADK, and 6-ETI was toxic to MM cell lines and primary specimens and had a robust antitumor effect in a disseminated MM mouse model. Several nucleoside analogs are effective in treating leukemias and T cell lymphomas, and 6-ETI may fill this niche for the treatment of PEL, plasmablastic lymphoma, MM, and other ADK-expressing cancers.
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http://dx.doi.org/10.1172/JCI83936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5451239PMC
June 2017

Does persistent HIV replication explain continued lymphoma incidence in the era of effective antiretroviral therapy?

Curr Opin Virol 2016 10 23;20:71-77. Epub 2016 Sep 23.

Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, United States. Electronic address:

Non-Hodgkin lymphomas are highly increased in incidence in individuals infected with HIV, and this continues to be the case in spite of highly effective combined antiretroviral therapy (cART). New evidence has demonstrated that while successful virtual recovery of CD4 counts and elimination of HIV from peripheral blood can be achieved with cART, viral replication can still occur in lymphoid tissues. In addition, recent studies have suggested that adipose tissue provides an additional reservoir for HIV-infected macrophages and T lymphocytes even in the context of successful cART therapy. In this review article, we discuss possible mechanisms leading to the development of lymphoma in the cART era.
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http://dx.doi.org/10.1016/j.coviro.2016.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102761PMC
October 2016

Kaposi Sarcoma Herpesvirus Induces HO-1 during De Novo Infection of Endothelial Cells via Viral miRNA-Dependent and -Independent Mechanisms.

mBio 2015 Jun 4;6(3):e00668. Epub 2015 Jun 4.

Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon, USA

Unlabelled: Kaposi sarcoma (KS) herpesvirus (KSHV) infection of endothelial cells (EC) is associated with strong induction of heme oxygenase-1 (HO-1), a stress-inducible host gene that encodes the rate-limiting enzyme responsible for heme catabolism. KS is an angioproliferative tumor characterized by the proliferation of KSHV-infected spindle cells, and HO-1 is highly expressed in such cells. HO-1 converts the pro-oxidant, proinflammatory heme molecule into metabolites with antioxidant, anti-inflammatory, and proliferative activities. Previously published work has shown that KSHV-infected EC in vitro proliferate in response to free heme in a HO-1-dependent manner, thus implicating virus-enhanced HO-1 activity in KS tumorigenesis. The present study investigated the molecular mechanisms underlying KSHV induction of HO-1 in lymphatic EC (LEC), which are the likely spindle cell precursors. In a time course analysis of KSHV-infected cells, HO-1 expression displays biphasic kinetics characterized by an early transient induction that is followed by a more sustained upregulation coincident with the establishment of viral latency. A viral microRNA miR-K12-11 deletion mutant of KSHV was found to be defective for induction of HO-1 during latency. A potential mechanism for this phenotype was provided by BACH1, a cellular HO-1 transcriptional repressor targeted by miR-K12-11. In fact, in KSHV-infected LEC, the BACH1 message level is reduced, BACH1 subcellular localization is altered, and miR-K12-11 mediates the inverse regulation of HO-1 and BACH1 during viral latency. Interestingly, the data indicate that neither miR-K12-11 nor de novo KSHV gene expression is required for the burst of HO-1 expression observed at early times postinfection, which suggests that additional virion components promote this phenotype.

Importance: While the mechanisms underlying KSHV induction of HO-1 remain unknown, the cellular mechanisms that regulate HO-1 expression have been extensively investigated in the context of basal and pathophysiological states. The detoxifying action of HO-1 is critical for the protection of cells exposed to high heme levels. KS spindle cells are erythrophagocytic and contain erythrocyte ghosts. Erythrocyte degeneration leads to the localized release of heme, creating oxidative stress that may be further exacerbated by environmental or other cofactors. Our previous work showed that KSHV-infected cells proliferate in response to heme and that this occurs in a HO-1-dependent manner. We therefore hypothesize that KSHV induction of HO-1 contributes to KS tumor development via heme metabolism and propose that HO-1 be evaluated as a therapeutic target for KS. Our present work, which aimed to understand the mechanisms whereby KSHV induces HO-1, will be important for the design and implementation of such a strategy.
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http://dx.doi.org/10.1128/mBio.00668-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4462627PMC
June 2015

Flow sorting and exome sequencing reveal the oncogenome of primary Hodgkin and Reed-Sternberg cells.

Blood 2015 Feb 8;125(7):1061-72. Epub 2014 Dec 8.

Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY;

Classical Hodgkin lymphoma (cHL) is characterized by sparsely distributed Hodgkin and Reed-Sternberg (HRS) cells amid reactive host background, complicating the acquisition of neoplastic DNA without extensive background contamination. We overcame this limitation by using flow-sorted HRS and intratumor T cells and optimized low-input exome sequencing of 10 patient samples to reveal alterations in genes involved in antigen presentation, chromosome integrity, transcriptional regulation, and ubiquitination. β-2-microglobulin (B2M) is the most commonly altered gene in HRS cells, with 7 of 10 cases having inactivating mutations that lead to loss of major histocompatibility complex class I (MHC-I) expression. Enforced wild-type B2M expression in a cHL cell line restored MHC-I expression. In an extended cohort of 145 patients, the absence of B2M protein in the HRS cells was associated with lower stage of disease, younger age at diagnosis, and better overall and progression-free survival. B2M-deficient cases encompassed most of the nodular sclerosis subtype cases and only a minority of mixed cellularity cases, suggesting that B2M deficiency determines the tumor microenvironment and may define a major subset of cHL that has more uniform clinical and morphologic features. In addition, we report previously unknown genetic alterations that may render selected patients sensitive to specific targeted therapies.
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http://dx.doi.org/10.1182/blood-2014-11-610436DOI Listing
February 2015

CXCR7 expression disrupts endothelial cell homeostasis and causes ligand-dependent invasion.

Cell Adh Migr 2014 ;8(2):165-76

Vaccine and Gene Therapy Institute; Oregon Health and Science University; Portland, OR USA.

The homeostatic function of endothelial cells (EC) is critical for a number of physiological processes including vascular integrity, immunity, and wound healing. Indeed, vascular abnormalities resulting from EC dysfunction contribute to the development and spread of malignancies. The alternative SDF-1/CXCL12 receptor CXCR7 is frequently and specifically highly expressed in tumor-associated vessels. In this study, we investigate whether CXCR7 contributes to vascular dysfunction by specifically examining the effect of CXCR7 expression on EC barrier function and motility. We demonstrate that CXCR7 expression in EC results in redistribution of CD31/PECAM-1 and loss of contact inhibition. Moreover, CXCR7+ EC are deficient in barrier formation. We show that CXCR7-mediated motility has no influence on angiogenesis but contributes to another motile process, the invasion of CXCR7+ EC into ligand-rich niches. These results identify CXCR7 as a novel manipulator of EC barrier function via alteration of PECAM-1 homophilic junctions. As such, aberrant expression of CXCR7 in the vasculature has the potential to disrupt vascular homeostasis and could contribute to vascular dysfunction in cancer systems.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4049862PMC
http://dx.doi.org/10.4161/cam.28495DOI Listing
May 2015

Aberrant proliferation in CXCR7+ endothelial cells via degradation of the retinoblastoma protein.

PLoS One 2013 23;8(7):e69828. Epub 2013 Jul 23.

Vaccine and Gene Therapy Institute, Oregon Health and Science University, Portland, Oregon, USA.

Angiogenesis is a critical factor in the growth and dissemination of solid tumors. Indeed, tumor vasculature is abnormal and contributes to the development and spread of malignancies by creating a hostile microenvironment. The alternative SDF-1/CXCL12 receptor, CXCR7, is frequently and specifically expressed in tumor-associated vessels. In this study, we examine the role of endothelium-expressed CXCR7 in tumor vascular dysfunction by specifically examining the contribution of CXCR7 to endothelial cell (EC) proliferation. We demonstrate that CXCR7 expression is sufficient to drive post-confluent growth in EC cultures. Further, we provide a novel mechanism for CXCR7-mediated proliferation via proteasomal degradation of the tumor suppressor protein Rb. These findings identify a heretofore unappreciated role for CXCR7 in vascular dysfunction and confirm this receptor as a plausible target for anti-tumor therapy.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0069828PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3720914PMC
March 2014