Molecular and clinical analyses of PHF6 mutant myeloid neoplasia provide their pathogenesis and therapeutic targeting

PHF6 mutations (PHF6MT) are identified in various myeloid neoplasms (MN). However, little is known about the precise function and consequences of PHF6 in MN. Here we show three main findings in our comprehensive genomic and proteomic study. Firstly, we show a different pattern of genes correlating with PHF6MT in male and female cases. When analyzing male and female cases separately, in only male cases, RUNX1 and U2AF1 are co-mutated with PHF6. In contrast, female cases reveal co-occurrence of ASXL1 mutations and X-chromosome deletions with PHF6MT. Next, proteomics analysis reveals a direct interaction between PHF6 and RUNX1. Both proteins co-localize in active enhancer regions that define the context of lineage differentiation. Finally, we demonstrate a negative prognostic role of PHF6MT, especially in association with RUNX1. The negative effects on survival are additive as PHF6MT cases with RUNX1 mutations have worse outcomes when compared to cases carrying single mutation or wild-type.

TET2 mutation as prototypic clonal hematopoiesis lesion

Loss of function TET2 mutation (TET2MT) is one of the most frequently observed lesions in clonal hematopoiesis (CH). TET2 a member TET-dioxygenase family of enzymes that along with TET1 and TET3, progressively oxidize 5-methyl cytosine (mC) resulting in regulated demethylation of promoter, enhancer and silencer elements of the genome. This process is critical for efficient transcription that determine cell lineage fate, proliferation and survival and the maintenance of the genomic fidelity with aging of the organism. Partial or complete loss-of-function TET2 mutations create regional and contextual DNA hypermethylation leading to gene silencing or activation that result in skewed myeloid differentiation and clonal expansion. In addition to myeloid skewing, loss of TET2 creates differentiation block and provides proliferative advantage to hematopoietic stem and progenitor cells (HSPCs). TET2MT is a prototypical lesion in CH, since the mutant clones dominate during stress hematopoiesis and often associates with evolution of myeloid malignancies. TET2MT clones has unique privilege to create and persist in pro-inflammatory milieu. Despite extensive knowledge regarding biochemical mechanisms underlying distorted myeloid differentiation, and enhanced self-replication of TET2MT HSPC, the mechanistic link of various pathogenesis associated with TET2 loss in CHIP is less understood. Here we review the recent development in TET2 biology and its probable mechanistic link in CH with aging and inflammation. We also explored the therapeutic strategies of targeting TET2MT associated CHIP and the utility of targeting TET2 in normal hematopoiesis and somatic cell reprograming. We explore the biochemical mechanisms and candidate therapies that emerged in last decade of research.

Multiple Myeloma Therapy: Emerging Trends and Challenges

Multiple myeloma (MM) is a complex hematologic malignancy characterized by the uncontrolled proliferation of clonal plasma cells in the bone marrow that secrete large amounts of immunoglobulins and other non-functional proteins. Despite decades of progress and several landmark therapeutic advancements, MM remains incurable in most cases. Standard of care frontline therapies have limited durable efficacy, with the majority of patients eventually relapsing, either early or later. Induced drug resistance via up-modulations of signaling cascades that circumvent the effect of drugs and the emergence of genetically heterogeneous sub-clones are the major causes of the relapsed-refractory state of MM. Cytopenias from cumulative treatment toxicity and disease refractoriness limit therapeutic options, hence creating an urgent need for innovative approaches effective against highly heterogeneous myeloma cell populations. Here, we present a comprehensive overview of the current and future treatment paradigm of MM, and highlight the gaps in therapeutic translations of recent advances in targeted therapy and immunotherapy. We also discuss the therapeutic potential of emerging preclinical research in multiple myeloma.

Rare germline alterations of myeloperoxidase predispose to myeloid neoplasms

Myeloperoxidase (MPO) gene alterations with variable clinical penetrance have been found in hereditary MPO deficiency, but their leukemia association in patients and carriers has not been established. Germline MPO alterations were found to be significantly enriched in myeloid neoplasms: 28 pathogenic/likely pathogenic variants were identified in 100 patients. The most common alterations were c.2031-2 A > C, R569W, M519fs* and Y173C accounting for about half of the cases. While functional experiments showed that the marrow stem cell pool of Mpo^-/- mice was not increased, using competitive repopulation demonstrated that Mpo^-/- grafts gained growth advantage over MPO wild type cells. This finding also correlated with increased clonogenic potential after serial replating in the setting of H₂O₂-induced oxidative stress. Furthermore, we demonstrated that H₂O₂-induced DNA damage and activation of error-prone DNA repair may result in secondary genetic damage potentially predisposing to leukemia leukemic evolution. In conclusion, our study for the first time demonstrates that germline MPO variants may constitute risk alleles for MN evolution.

Sulfur Amino Acid Supplementation Abrogates Protective Effects of Caloric Restriction for Enhancing Bone Marrow Regrowth Following Ionizing Radiation

Radiation therapy damages and depletes total bone marrow (BM) cellularity, compromising safety and limiting effective dosing. Aging also strains total BM and BM hematopoietic stem and progenitor cell (HSPC) renewal and function, resulting in multi-system defects. Interventions that preserve BM and BM HSPC homeostasis thus have potential clinical significance. Here, we report that 50% calorie restriction (CR) for 7-days or fasting for 3-days prior to irradiation improved mouse BM regrowth in the days and weeks post irradiation. Specifically, one week of 50% CR ameliorated loss of total BM cellularity post irradiation compared to ad libitum-fed controls. CR-mediated BM protection was abrogated by dietary sulfur amino acid (i.e., cysteine, methionine) supplementation or pharmacological inhibition of sulfur amino acid metabolizing and hydrogen sulfide (H₂S) producing enzymes. Up to 2-fold increased proliferative capacity of ex vivo-irradiated BM isolated from food restricted mice relative to control mice indicates cell autonomy of the protective effect. Pretreatment with H₂S in vitro was sufficient to preserve proliferative capacity by over 50% compared to non-treated cells in ex vivo-irradiated BM and BM HSPCs. The exogenous addition of H₂S inhibited Ten eleven translocation 2 (TET2) activity in vitro, thus providing a potential mechanism of action. Short-term CR or fasting therefore offers BM radioprotection and promotes regrowth in part via altered sulfur amino acid metabolism and H₂S generation, with translational implications for radiation treatment and aging.

Circulating microbial content in myeloid malignancy patients is associated with disease subtypes and patient outcomes

Although recent work has described the microbiome in solid tumors, microbial content in hematological malignancies is not well-characterized. Here we analyze existing deep DNA sequence data from the blood and bone marrow of 1870 patients with myeloid malignancies, along with healthy controls, for bacterial, fungal, and viral content. After strict quality filtering, we find evidence for dysbiosis in disease cases, and distinct microbial signatures among disease subtypes. We also find that microbial content is associated with host gene mutations and with myeloblast cell percentages. In patients with low-risk myelodysplastic syndrome, we provide evidence that Epstein-Barr virus status refines risk stratification into more precise categories than the current standard. Motivated by these observations, we construct machine-learning classifiers that can discriminate among disease subtypes based solely on bacterial content. Our study highlights the association between the circulating microbiome and patient outcome, and its relationship with disease subtype.

Eltrombopag inhibits TET dioxygenase to contribute to hematopoietic stem cell expansion in aplastic anemia

Eltrombopag, an FDA-approved non-peptidyl thrombopoietin receptor agonist, is clinically used for the treatment of aplastic anemia, a disease characterized by hematopoietic stem cell failure and pancytopenia, to improve platelet counts and stem cell function. Eltrombopag treatment results in a durable trilineage hematopoietic expansion in patients. Some of the eltrombopag hematopoietic activity has been attributed to its off-target effects, including iron chelation properties. However, the mechanism of action for its full spectrum of clinical effects is still poorly understood. Here, we report that eltrombopag bound to the TET2 catalytic domain and inhibited its dioxygenase activity, which was independent of its role as an iron chelator. The DNA demethylating enzyme TET2, essential for hematopoietic stem cell differentiation and lineage commitment, is frequently mutated in myeloid malignancies. Eltrombopag treatment expanded TET2-proficient normal hematopoietic stem and progenitor cells, in part because of its ability to mimic loss of TET2 with simultaneous thrombopoietin receptor activation. On the contrary, TET inhibition in TET2 mutant malignant myeloid cells prevented neoplastic clonal evolution in vitro and in vivo. This mechanism of action may offer a restorative therapeutic index and provide a scientific rationale to treat selected patients with TET2 mutant-associated or TET deficiency-associated myeloid malignancies.

The similarity of class II HLA genotypes defines patterns of autoreactivity in idiopathic bone marrow failure disorders

Idiopathic aplastic anemia (IAA) is a rare autoimmune bone marrow failure (BMF) disorder initiated by a human leukocyte antigen (HLA)-restricted T-cell response to unknown antigens. As in other autoimmune disorders, the predilection for certain HLA profiles seems to represent an etiologic factor; however, the structure-function patterns involved in the self-presentation in this disease remain unclear. Herein, we analyzed the molecular landscape of HLA complexes of a cohort of 300 IAA patients and almost 3000 healthy and disease controls by deeply dissecting their genotypic configurations, functional divergence, self-antigen binding capabilities, and T-cell receptor (TCR) repertoire specificities. Specifically, analysis of the evolutionary divergence of HLA genotypes (HED) showed that IAA patients carried class II HLA molecules whose antigen-binding sites were characterized by a high level of structural homology, only partially explained by specific risk allele profiles. This pattern implies reduced HLA binding capabilities, confirmed by binding analysis of hematopoietic stem cell (HSC)-derived self-peptides. IAA phenotype was associated with the enrichment in a few amino acids at specific positions within the peptide-binding groove of DRB1 molecules, affecting the interface HLA-antigen-TCR β and potentially constituting the basis of T-cell dysfunction and autoreactivity. When analyzing associations with clinical outcomes, low HED was associated with risk of malignant progression and worse survival, underlying reduced tumor surveillance in clearing potential neoantigens derived from mechanisms of clonal hematopoiesis. Our data shed light on the immunogenetic risk associated with IAA etiology and clonal evolution and on general pathophysiological mechanisms potentially involved in other autoimmune disorders.

Clinical and basic implications of dynamic T cell receptor clonotyping in hematopoietic cell transplantation

TCR repertoire diversification constitutes a foundation for successful immune reconstitution after allogeneic hematopoietic cell transplantation (allo-HCT). Deep TCR Vβ sequencing of 135 serial specimens from a cohort of 35 allo-HCT recipients/donors was performed to dissect posttransplant TCR architecture and dynamics. Paired analysis of clonotypic repertoires showed a minimal overlap with donor expansions. Rarefied and hyperexpanded clonotypic patterns were hallmarks of T cell reconstitution and influenced clinical outcomes. Donor and pretransplant TCR diversity as well as divergence of class I human leukocyte antigen genotypes were major predictors of recipient TCR repertoire recovery. Complementary determining region 3–based specificity spectrum analysis indicated a predominant expansion of pathogen- and tumor-associated clonotypes in the late post–allo-HCT phase, while autoreactive clones were more expanded in the case of graft-versus-host disease occurrence. These findings shed light on post–allo-HCT adaptive immune reconstitution processes and possibly help in tracking alloreactive responses.

Therapeutic Targeting of Protein Disulfide Isomerase PDIA1 in Multiple Myeloma

Multiple myeloma is a genetically complex hematologic neoplasia in which malignant plasma cells constantly operate at the maximum limit of their unfolded protein response (UPR) due to a high secretory burden of immunoglobulins and cytokines. The endoplasmic reticulum (ER) resident protein disulfide isomerase, PDIA1 is indispensable for maintaining structural integrity of cysteine-rich antibodies and cytokines that require accurate intramolecular disulfide bond arrangement. PDIA1 expression analysis from RNA-seq of multiple myeloma patients demonstrated an inverse relationship with survival in relapsed or refractory disease, supporting its critical role in myeloma persistence. Using a structure-guided medicinal chemistry approach, we developed a potent, orally bioavailable small molecule PDIA1 inhibitor CCF642-34. The inhibition of PDIA1 overwhelms the UPR in myeloma cells, resulting in their apoptotic cell death at doses that do not affect the normal CD34⁺ hematopoietic stem and progenitor cells. Bortezomib resistance leads to increased PDIA1 expression and thus CCF642-34 sensitivity, suggesting that proteasome inhibitor resistance leads to PDIA1 dependence for proteostasis and survival. CCF642-34 induces acute unresolvable UPR in myeloma cells, and oral treatment increased survival of mice in the syngeneic 5TGM1 model of myeloma. Results support development of CCF642-34 to selectively target the plasma cell program and overcome the treatment-refractory state in myeloma.

Interaction of tacrolimus through hedgehog signaling pathway: An in vitro evaluation using rat hepatocytes

Tacrolimus (TAC) is the drug of choice in immunosuppressive therapy for organ transplantation; however, adverse effects are still a major concern. The current study aims to decipher the short-term exposure of TAC on rat hepatocytes in relation to activation of hedgehog (HH) signaling pathway. Time dependent study was conducted using primary rat hepatocytes treated with TAC (36 µM) for 6, 12, 24 and 48 h. Western blot analysis was performed using cell lysate in order to analyze the regulation of HH pathway proteins including HHIP, SMO, PTCH, IHH, SHH, and GLI transcription factors. The study revealed change in protein expression of HH signaling molecules with activation of HH pathway, due to downregulation of HHIP, and enrichment of HH ligands with activation of SMO and GLI transcription factors. It is therefore, concluded that short term TAC exposure leads to upregulation of HH pathway in liver, which may initially act to repair the liver damage but can worsen the condition in case of prolonged immunosuppressive therapy. This insight could lead to understand association of off target effects of immunosuppressive drugs and occurrence of other liver diseases in transplant patients when it comes to long term immunosuppressive therapy. These findings also illuminate a novel direction that use of HH inhibitor might provide a therapeutic strategy for immune suppression related liver disorders.

SAR insights into TET2 catalytic domain inhibition: Synthesis of 2-Hydroxy-4-Methylene-pentanedicarboxylates

The TET (Ten-Eleven Translocation) dioxygenase enzyme family comprising 3 members, TET1-3, play key roles in DNA demethylation. These processes regulate transcription programs that determine cell lineage, survival, proliferation, and differentiation. The impetus for our investigations described here is derived from the need to develop illuminating small molecule probes for TET enzymes with cellular activity and specificity. The studies were done so in the context of the importance of TET2 in the hematopoietic system and the preponderance of loss of function somatic TET2 mutations in myeloid diseases. We have identified that 2-hydroxy-4-methylene-pentanedicarboxylic acid 2a reversibly competes with the co-substrate α-KG in the TET2 catalytic domain and inhibits the dioxygenase activity with an IC₅₀ = 11.0 ± 0.9 μM at 10 μM α-KG in a cell free system and binds in the TET2 catalytic domain with K_d = 0.3 ± 0.12 μM.

Decitabine- and 5-azacytidine resistance emerges from adaptive responses of the pyrimidine metabolism network

Mechanisms-of-resistance to decitabine and 5-azacytidine, mainstay treatments for myeloid malignancies, require investigation and countermeasures. Both are nucleoside analog pro-drugs processed by pyrimidine metabolism into a deoxynucleotide analog that depletes the key epigenetic regulator DNA methyltranseferase 1 (DNMT1). Here, upon serial analyses of DNMT1 levels in patients' bone marrows on-therapy, we found DNMT1 was not depleted at relapse. Showing why, bone marrows at relapse exhibited shifts in expression of key pyrimidine metabolism enzymes in directions adverse to pro-drug activation. Further investigation revealed the origin of these shifts. Pyrimidine metabolism is a network that senses and regulates deoxynucleotide amounts. Deoxynucleotide amounts were disturbed by single exposures to decitabine or 5-azacytidine, via off-target depletion of thymidylate synthase and ribonucleotide reductase respectively. Compensating pyrimidine metabolism shifts peaked 72-96 h later. Continuous pro-drug exposures stabilized these adaptive metabolic responses to thereby prevent DNMT1-depletion and permit exponential leukemia out-growth as soon as day 40. The consistency of the acute metabolic responses enabled exploitation: simple treatment modifications in xenotransplant models of chemorefractory leukemia extended noncytotoxic DNMT1-depletion and leukemia control by several months. In sum, resistance to decitabine and 5-azacytidine originates from adaptive responses of the pyrimidine metabolism network; these responses can be anticipated and thus exploited.

TET-dioxygenase deficiency in oncogenesis and its targeting for tumor-selective therapeutics

TET2 is one of the most frequently mutated genes in myeloid neoplasms. TET2 loss-of-function perturbs myeloid differentiation and causes clonal expansion. Despite extensive knowledge regarding biochemical mechanisms underlying distorted myeloid differentiation, targeted therapies are lagging. Here we review known biochemical mechanisms and candidate therapies that emerge from this. Specifically, we discuss the potential utility of vitamin C to compensate for TET-dioxygenase deficiency, to thereby restore the biochemical function. An alternative approach exploits the TET-deficient state for synthetic lethality, exploiting the fact that a minimum level of TET-dioxygenase activity is required for cell survival, rendering TET2-mutant malignant cells selectively vulnerable to inhibitors of TET-function.

DNA methylation inhibition in myeloma: Experience from a phase 1b study of low-dose continuous azacitidine in combination with lenalidomide and low-dose dexamethasone in relapsed or refractory multiple myeloma

The DNA methyltransferase inhibitor azacytidine (aza) may reactivate pathways associated with plasma cell differentiation, cell cycle control, apoptosis, and immune recognition and thereby restore sensitivity to lenalidomide (len) and dexamethasone (dex) in relapsed and/or refractory multiple myeloma (RRMM). We aimed to develop an aza regimen that reaches epigenetically active levels 8 times in 28 days with less bone marrow toxicity than the myeloid malignancy standard of 7 consecutive doses to enable safe combination with len. Aza was escalated from 30 mg/m² once a week up to a predefined maximum of 50 mg/m² twice a week in combination with GFR-adjusted len (≥ 60 mL/min: 25 mg, 3059 mL/min: 10 mg) day 1 to 21 every 28 days and dex 40 mg once a week followed by a limited expansion study to a total N of 23 at the highest tolerated dose. Fifty-one patients (pts) with RRMM were screened, 42 were treated and 41 were evaluable for response based on at least 1 response assessment or progression after treatment start. The median number of prior lines of therapy was 5 (1-11) and 81% (34) were refractory to len and/or pomalidomide (pom). Two DLTs occurred in different cohorts, 1 neutropenic fever in 1/6 pts on the aza 40 mg/m² twice a week GFR ≥ 60 mL/min cohort and 1 GGT elevation in 1/6 pts on the aza 50 mg/m² GFR 30-59 mL/min cohort. An MTD was not reached and aza 50 mg/m² SC twice a week was chosen for the expansion study. At least possibly related Grade 3/4 AEs occurred in 28 pts (67%) with the following in > 1 pt: neutropenia (N = 16, 38%), anemia (N = 6, 14%), lymphopenia (N = 5, 12%), thrombocytopenia (N = 4, 10%), leukopenia (N = 4, 10%), febrile neutropenia (N = 4, 10%), fatigue (N = 3, 7%), fever (N = 2, 5%), and infection (N = 2, 5%). At a median follow up time for alive pts of 60.2 months (range: 36.1-82.5 months), the overall response rate (≥ partial response) and clinical benefit response rate (≥ minor response) was 22 and 32%, respectively, with 4 very good partial responses (10%), 5 partial responses (12%), and 4 minor responses (10%). The median PFS was 3.1 months (95% confidence interval [CI]: 2.1-5.1 months), median TTP 2.7 months (95% CI: 2.1-7.5 months), and median OS 18.6 months (95% CI: 12.9-33.0 months). Achieving at least minor response and reaching TTP > 6 months was associated with approximately 35% lower median plasma levels of the enzyme that inactivates aza, plasma cytidine deaminase (CDA, P< .0001). Two of the len refractory pts achieved longer disease control than with any prior regimen and 1 responded immediately after progression on len, bortezomib, and prednisone. Analyses of the methylation state of over 480,000 CpG sites in purified myeloma cells at screening were possible in 11 pts and on day 28 in 8 of them. As in other studies, the majority of differentially methylated CpGs compared to normal plasma cells were hypomethylated in myeloma. Treatment decreased the number of CpGs that were differentially methylated in normal plasma cells by > 0.5% in 6 and by > 5% in 3 of the 8 pts, most pronounced in 2 pts with clinically convincing aza contribution who achieved a reduction in overall differentially methylated CpGs by 23 and 68%, respectively, associated with increased expression of immunoglobulin genes. The study demonstrated tolerability of twice a week SC aza at 50 mg/m² with len and dex in RRMM and suggested aza may help overcome the len/pom refractory state, possibly by activating differentiation pathways. Relatively low response rates and association of clinical benefit with low plasma levels of the aza inactivating enzyme CDA suggest the aza regimen will need to be optimized further and pt selection may be required to maximize benefit.

Epigenetic modifier directed therapeutics to unleash healthy genes in unhealthy cells

A common thread through malignant and nonmalignant diseases alerts us to a therapeutic opportunity to seize: disease may originate from genetic mutations, but resulting maladaptive/unhealthy cell fates and functions are mediated by epigenetic enzymes, that are druggable. Epigenetic enzymes modify DNA, and/or the histones around which DNA is organized, to regulate access to genes by the basal transcription factor machinery that transcribes genes. Epigenetic enzymes can be divided usefully into those that facilitate gene transcription ("on" enzymes or coactivators) and those that favor gene repression ("off" enzymes or corepressors). DNA-binding master transcription factors cooperate to recruit coactivators, and repulse corepressors, from thousands of genes, to thereby activate the gene expression programs that define cell fates and functions. In malignancy, this usual exchange of corepressors for coactivators fails, because of mutations to master transcription factors or the coactivators they recruit. Inhibiting corepressor enzymes using small molecules uses pharmacology to redress this coactivator/corepressor imbalance that originates from genetics, to in this way release cancer cells to the terminal lineage-fates intended by their master transcription factor content. Similarly, in nonmalignant β-hemoglobinopathies, inhibiting corepressors exploits transcription factor and lineage-context to activate unmutated fetal over mutated adult globin genes, to thereby treat these nonmalignant genetic diseases. Master transcription factors then are the "natural forces" in the Hippocratic dictum "Natural forces within us are the true healers of disease," and drugging epigenetic enzymes (corepressors) a way to harness these forces to heal.

A Therapeutic Strategy for Preferential Targeting of TET2 Mutant and TET-dioxygenase Deficient Cells in Myeloid Neoplasms

TET2 is frequently mutated in myeloid neoplasms. Genetic TET2 deficiency leads to skewed myeloid differentiation and clonal expansion, but minimal residual TET activity is critical for survival of neoplastic progenitor and stem cells. Consistent with mutual exclusivity of TET2 and neomorphic IDH1/2 mutations, here we report that IDH1/2 mutant-derived 2-hydroxyglutarate is synthetically lethal to TET-dioxygenase deficient cells. In addition, a TET-selective small molecule inhibitor decreased cytosine hydroxymethylation and restricted clonal outgrowth of TET2 mutant, but not normal hematopoietic precursor cells in vitro and in vivo. While TET-inhibitor phenocopied somatic TET2 mutations, its pharmacologic effects on normal stem cells were, unlike mutations, reversible. Treatment with TET inhibitor suppressed the clonal evolution of TET2 mutant cells in murine models and TET2-mutated human leukemia xenografts. These results suggest that TET inhibitors may constitute a new class of targeted agents in TET2 mutant neoplasia.

Context dependent effects of ascorbic acid treatment in TET2 mutant myeloid neoplasia

Loss-of-function TET2 mutations (TET2^MT) are common in myeloid neoplasia. TET2, a DNA dioxygenase, requires 2-oxoglutarate and Fe(II) to oxidize 5-methylcytosine. TET2^MT thus result in hypermethylation and transcriptional repression. Ascorbic acid (AA) increases dioxygenase activity by facilitating Fe(III)/Fe(II) redox reaction and may alleviate some biological consequences of TET2^MT by restoring dioxygenase activity. Here, we report the utility of AA in the prevention of TET2^MT myeloid neoplasia (MN), clarify the mechanistic underpinning of the TET2-AA interactions, and demonstrate that the ability of AA to restore TET2 activity in cells depends on N- and C-terminal lysine acetylation and nature of TET2^MT. Consequently, pharmacologic modulation of acetyltransferases and histone deacetylases may regulate TET dioxygenase-dependent AA effects. Thus, our study highlights the contribution of factors that may enhance or attenuate AA effects on TET2 and provides a rationale for novel therapeutic approaches including combinations of AA with class I/II HDAC inhibitor or sirtuin activators in TET2^MT leukemia.

Using TET2- and ascorbic acid deficient model systems Guan et al show that long term treatment with ascorbic acid delays myeloid neoplasia in mice and reveal a complex interplay of post-translational modification of lysine residues that modulate TET2 activity in neoplastic evolution.

Suppressing PARylation by 2',5'-oligoadenylate synthetase 1 inhibits DNA damage-induced cell death

High expression of 2',5'-oligoadenylate synthetase 1 (OAS1), which adds AMP residues in 2',5' linkage to a variety of substrates, is observed in many cancers as a part of the interferon-related DNA damage resistance signature (IRDS). Poly(ADP-ribose) (PAR) is rapidly synthesized from NAD⁺ at sites of DNA damage to facilitate repair, but excessive PAR synthesis due to extensive DNA damage results in cell death by energy depletion and/or activation of PAR-dependent programmed cell death pathways. We find that OAS1 adds AMP residues in 2',5' linkage to PAR, inhibiting its synthesis in vitro and reducing its accumulation in cells. Increased OAS1 expression substantially improves cell viability following DNA-damaging treatments that stimulate PAR synthesis during DNA repair. We conclude that high expression of OAS1 in cancer cells promotes their ability to survive DNA damage by attenuating PAR synthesis and thus preventing cell death.

Leukemogenic nucleophosmin mutation disrupts the transcription factor hub that regulates granulomonocytic fates

Nucleophosmin (NPM1) is among the most frequently mutated genes in acute myeloid leukemia (AML). It is not known, however, how the resulting oncoprotein mutant NPM1 is leukemogenic. To reveal the cellular machinery in which NPM1 participates in myeloid cells, we analyzed the endogenous NPM1 protein interactome by mass spectrometry and discovered abundant amounts of the master transcription factor driver of monocyte lineage differentiation PU.1 (also known as SPI1). Mutant NPM1, which aberrantly accumulates in cytoplasm, dislocated PU.1 into cytoplasm with it. CEBPA and RUNX1, the master transcription factors that collaborate with PU.1 to activate granulomonocytic lineage fates, remained nuclear; but without PU.1, their coregulator interactions were toggled from coactivators to corepressors, repressing instead of activating more than 500 granulocyte and monocyte terminal differentiation genes. An inhibitor of nuclear export, selinexor, by locking mutant NPM1/PU.1 in the nucleus, activated terminal monocytic fates. Direct depletion of the corepressor DNA methyltransferase 1 (DNMT1) from the CEBPA/RUNX1 protein interactome using the clinical drug decitabine activated terminal granulocytic fates. Together, these noncytotoxic treatments extended survival by more than 160 days versus vehicle in a patient-derived xenotransplant model of NPM1/FLT3-mutated AML. In sum, mutant NPM1 represses monocyte and granulocyte terminal differentiation by disrupting PU.1/CEBPA/RUNX1 collaboration, a transforming action that can be reversed by pharmacodynamically directed dosing of clinical small molecules.

Case study: patient-derived clear cell adenocarcinoma xenograft model longitudinally predicts treatment response

There has been little progress in the use of patient-derived xenografts (PDX) to guide individual therapeutic strategies. In part, this can be attributed to the operational challenges of effecting successful engraftment and testing multiple candidate drugs in a clinically workable timeframe. It also remains unclear whether the ancestral tumor will evolve along similar evolutionary trajectories in its human and rodent hosts in response to similar selective pressures (i.e., drugs). Herein, we combine a metastatic clear cell adenocarcinoma PDX with a timely 3 mouse x 1 drug experimental design, followed by a co-clinical trial to longitudinally guide a patient's care. Using this approach, we accurately predict response to first- and second-line therapies in so far as tumor response in mice correlated with the patient's clinical response to first-line therapy (gemcitabine/nivolumab), development of resistance and response to second-line therapy (paclitaxel/neratinib) before these events were observed in the patient. Treatment resistance to first-line therapy in the PDX is coincident with biologically relevant changes in gene and gene set expression, including upregulation of phase I/II drug metabolism (CYP2C18, UGT2A, and ATP2A1) and DNA interstrand cross-link repair (i.e., XPA, FANCE, FANCG, and FANCL) genes. A total of 5.3% of our engrafted PDX collection is established within 2 weeks of implantation, suggesting our experimental designs can be broadened to other cancers. These findings could have significant implications for PDX-based avatars of aggressive human cancers.

Abstract 1501: Developing novel strategy for the treatment of acute myeloid leukemia by targeting retinoic acid signaling pathways

Retinoic acid (RA), the active metabolite of vitamin A, influences biological processes by activating the retinoic acid receptor (RAR). RARs are ligand-controlled transcription factors that function as heterodimers with retinoid X receptors (RXRs) to regulate cell growth and survival. The success of RAR modulation in the treatment of acute promyelocytic leukaemia (APL) particularly by the use of all-trans retinoic acid (atRA) has stimulated considerable interest in the development of small molecules that can modulate RAR and RXR. Recent studies have demonstrated that RA can also activate the peroxisome proliferator-activated receptor β/δ (PPARβ/δ). In the aqueous intracellular milieu, RA is transported by the cellular retinoid-binding protein CRABP-II, or by the fatty-acid-binding protein FABP5, depending on the ratio of FABP5 to CRABP-II. In cells expressing high CRABP-II and low FABP5, RA activates the RAR, whereas in the presence of the reverse ratio, RA activates PPAR β/δ. These two different mode of RA delivery due to different ratio of these two cargos leads to opposite cellular outcomes. Cells harboring high level of CRABP-II, RA is delivered to RAR leading to apoptosis, growth arrest, and anticancer activity. However, when FABP5 expression is high RA is delivered to PPAR β/δ resulting in survival, proliferation, and tumor growth. In both cases, retinoid X receptor (RXR) is the indispensable partner of the nuclear receptor involved. The analysis of TCGA data set revealed that a certain class of AML patients have low level of CRABP-II and high level of FABP5, that in part explain the inability of at-RA to induce terminal differentiation in AML cells. To test our hypothesis, we screened AML and APL patient bone marrow cells and found that a number of AML patients bone marrow have high FABP5 and low CRABP-II protein levels while the atRA responding APL patients has opposite ratio determined by western blotting. Therefore, low CRABP-II and high FABP5 levels in a subset of AML patients lead to the activation of pro-survival PPAR β/δ pathway that promotes proliferation and opposes the differentiation. We also analyzed different AML cell lines for mRNA expression using qRT-PCR and protein by western blotting in using highly specific antibodies against FABP5 and CRABP-II. High FABP5 levels were observed in the majority of the AML cell lines. Efficacy of novel small molecule FABP5 inhibitor as a single agent and in combination with atRA was evaluated in HL-60 cells. Here, we demonstrate that a small molecule inhibitor of FABP5 synergizes with atRA and induces the differentiation in AML cells.

Citation Format: Metis Hasipek, Dale Grabowski, James G. Phillips, Yihong Guan, Hetty Carraway, Jaroslaw Maciejewski, Babal K. Jha. Developing novel strategy for the treatment of acute myeloid leukemia by targeting retinoic acid signaling pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1501.

Novel Protein Disulfide Isomerase Inhibitor with Anticancer Activity in Multiple Myeloma

Multiple myeloma cells secrete more disulfide bond-rich proteins than any other mammalian cell. Thus, inhibition of protein disulfide isomerases (PDI) required for protein folding in the endoplasmic reticulum (ER) should increase ER stress beyond repair in this incurable cancer. Here, we report the mechanistically unbiased discovery of a novel PDI-inhibiting compound with antimyeloma activity. We screened a 30,355 small-molecule library using a multilayered multiple myeloma cell-based cytotoxicity assay that modeled disease niche, normal liver, kidney, and bone marrow. CCF642, a bone marrow-sparing compound, exhibited a submicromolar IC50 in 10 of 10 multiple myeloma cell lines. An active biotinylated analog of CCF642 defined binding to the PDI isoenzymes A1, A3, and A4 in MM cells. In vitro, CCF642 inhibited PDI reductase activity about 100-fold more potently than the structurally distinct established inhibitors PACMA 31 and LOC14. Computational modeling suggested a novel covalent binding mode in active-site CGHCK motifs. Remarkably, without any further chemistry optimization, CCF642 displayed potent efficacy in an aggressive syngeneic mouse model of multiple myeloma and prolonged the lifespan of C57BL/KaLwRij mice engrafted with 5TGM1-luc myeloma, an effect comparable to the first-line multiple myeloma therapeutic bortezomib. Consistent with PDI inhibition, CCF642 caused acute ER stress in multiple myeloma cells accompanied by apoptosis-inducing calcium release. Overall, our results provide an illustration of the utility of simple in vivo simulations as part of a drug discovery effort, along with a sound preclinical rationale to develop a new small-molecule therapeutic to treat multiple myeloma. Cancer Res; 76(11); 3340-50. ©2016 AACR.

Crystal structure of the mouse hepatitis virus ns2 phosphodiesterase domain that antagonizes RNase L activation

Prior studies have demonstrated that the mouse hepatitis virus (MHV) A59 strain ns2 protein is a member of the 2H phosphoesterase family and exhibits 2',5'-phosphodiesterase (PDE) activity. During the IFN antiviral response, ns2 cleaves 2',5'-oligoadenylate (2-5A), a key mediator of RNase L activation, thereby subverting the activation of RNase L and evading host innate immunity. However, the mechanism of 2-5A cleavage by ns2 remains unclear. Here, we present the crystal structure of the MHV ns2 PDE domain and demonstrate a PDE fold similar to that of the cellular protein, a kinase anchoring protein 7 central domain (AKAP7(CD)) and rotavirus VP3 carboxy-terminal domain. The structure displays a pair of strictly conserved HxT/Sx motifs and forms a deep, positively charged catalytic groove with β-sheets and an arginine-containing loop. These findings provide insight into the structural basis for 2-5A binding of MHV ns2.

Menopausal Health Status of Women of Kapilvastu District of Nepal

BACKGROUND

Women face numerous health problems in their post-reproductive and menopausal years, including issues such as pelvic pain, incontinence and obstetric fistula. In Nepal, the importance of these health issues is increasing with the aging of the population, yet women are often unable to access adequate health care due to entrenched gender structures and misconceptions regarding menopause. This study aimed to describe the prevalence of menopause, the associated health problems and their severity amongst women aged 40-60 years in Kapilvastu.

METHODS

A descriptive study was conducted in Kapilvastu district. Multi stage cluster sampling technique was adopted: Illakas of Kapilvastu were identified, then one Village Development Committee (VDC) from each Illaka of the district, and two wards from each of these VDCs, were selected randomly.

RESULTS

The median age of onset of menopause was 47 years (25 th and 75 percentiles = 43 and 50 years), and >90% of women had entered menopause by 54. All symptoms in the Menopause Rating Scale were experienced to some extent by at least 30% of women, even amongst the premenopausal group. The most common problems experienced by menopausal women were: sexual problems (81.7%, 95%CI: 78.0-85.4), physical and mental exhaustion (81.5%, 95%CI: 77.8-85.2) and joint and muscular discomfort (78.5%, 95%CI: 74.6-82.4). The symptoms most frequently deemed "severe" or "very severe" were: sexual problems (40.5%), joint and muscular discomfort (27.4%), and sleep problems (21.0%). th

CONCLUSIONS

Middle-aged women in Kapilvastu experienced menopausal symptoms to a substantial degree. The prevalence and severity of these symptoms increased with the menopausal transition, and with increasing age. Menopause itself did not appear to be the primary risk factor for typical "menopausal" symptoms.

Abstract 4689: Targeting constitutive GLI activation in colon carcinomas and cancers with oncogenic KRAS signaling

The GLI genes, GLI1 and GLI2, encode transcription factors that regulate target genes at the distal end of the canonical Hedgehog signaling (HH) pathway (SHH-&gt;PTCH-&gt;SMO-&gt;GLI), tightly regulated in embryonic development, tissue patterning and differentiation. In cancers, both GLI1 and GLI2 are oncogenes, aberrantly and constitutively activated. Oncogene-driven signaling pathways, in particular KRAS/BRAF in colon cancer, circumvent the HH-GLI axis to further drive GLI activation, which serves as a nodal channel for oncogenic signals, and provides a pivotal role for GLI in cell survival. GANT61, a small molecule inhibitor of GLI-dependent transcription, terminates oncogenic HH-GLI and KRAS/BRAF-GLI signaling, inducing DNA damage and extensive cell death in seven human colon carcinoma cell line models examined. The overall goal is to understand how GANT61 induces cell death by inhibiting GLI-dependent transcription mechanisms. We have demonstrated that GANT61 is: a) specific for binding to GLI, and does not bind to DNA or to other transcription factors; b) selective for cancer cells vs normal cells that lack constitutive GLI activation. Inhibition of GLI1 and GLI2 by GANT61 rapidly reduces GLI binding to consensus sequences in target gene promoters and inhibits GLI-dependent transcription. Stalling of Pol II occurs adjacent to GLI binding regions at target gene promoters (FOXM1, BCL-2), associated with inhibition of GLI binding, enrichment of Pol II, and modification of promoter-bound pause (DSIF, NELF) or pause-release (P-TEFb) factors within a 300bp region of the FOXM1 promoter. Single-stranded DNA and RNA:DNA hybrids determining R-loop formation (distributed throughout the nucleoplasm) occur at sites of stalled Pol II, inhibited by RNAseH. Consistent with transcriptional inhibition, GANT61 induced DNA damage (γH2AX foci) in S-phase and non-S-phase cells, recognized at the initiation of S-phase (G1/S), prior to the onset of cell death. This may be due to one of two mechanisms: 1) The GLI1 target gene FOXM1, and its transcriptional target CDC6, downregulated in GANT61-treated cells, regulate Pre-Replication Complex assembly at G1/S thereby inhibiting the initiation of DNA replication; this controls outcome of the GANT61 response, dependent on GLI; 2) Transcriptional R-loop formation can conflict with DNA replication in GANT61-treated cells. These events inhibit initiation of DNA replication from unfired origins at early replicons and inhibit further progression through S-phase. GLI1 and/or GLI2 are constitutively activated in epithelial cancers of the GI tract, brain tumors, melanoma, pediatric solid tumors, liver, lung, breast, pancreatic and prostate cancers. Further, KRAS is mutated in one third of all human cancers and in 50% of colon carcinomas. Targeting GLI therefore has the potential for high impact in therapeutics, and is anticipated to lead to new approaches and therapeutic strategies for treating cancer.

Citation Format: Tapati Mazumdar, Babal K. Jha, Akwasi Agyeman, Janet A. Houghton. Targeting constitutive GLI activation in colon carcinomas and cancers with oncogenic KRAS signaling. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4689. doi:10.1158/1538-7445.AM2015-4689

Abstract 1759: Targeting GLI-dependent transcription by GANT61 in human colon carcinoma cells (CC); a new therapeutic approach

Colorectal cancer constitutes the second leading cause of cancer mortality in the United States with limited therapeutic options and poor survival for advanced stage disease. The GLI genes, GLI1 and GLI2, are transcription factors, which act at the distal end of the Hedgehog pathway (SHH-&gt;PTCH-&gt;SMO-&gt;GLI) to regulate organogenesis and differentiation in the colon. In cancer GLI1 and GLI2 are activated, are oncogenes, and we have shown are critical to the survival of colon carcinoma cells. Inhibition of GLI by the small molecule inhibitor, GANT61, induces extensive cell death downstream of γH2AX foci formation in CC. GANT61 rapidly reduces GLI binding to consensus sequences in target gene promoters (1 hr) and inhibits GLI1- and GLI2- dependent transcription. Using the known crystal structure of the five zinc finger GLI1-DNA complex we demonstrated, by computational docking, that GANT61 binds to the GLI1 protein, but not to the DNA binding site, via H bonds at amino acids E119 and E167. These sites lie within the groove between zinc fingers 2 and 3, on the opposite surface from, but in close proximity to, the GLI1-DNA binding regions. GANT61 is not observed to dock with DNA. The predicted binding constant for GANT61 (Kd = 2.6 μM) is consistent with GANT61 concentrations required to induce cell death in CC. Surface plasmon resonance (Biacore) confirmed the model predictions using immobilized GLI1 or DNA and GANT61 or GANT61/DNA as anylate, respectively (KD= 7.5 µM; IC50= 3.2μM). Following GANT61 treatment of CC we demonstrated transcriptional stalling of RNA Polymerase II (Pol II) at sites of early elongation adjacent to GLI binding regions at target gene promoters. This is associated with modification of promoter-bound pause (DSIF, NELF) or pause-release (P-TEFb) factors. Single-stranded DNA (R-loops) is detected at sites of stalled Pol II; γH2AX foci are induced. Consistent with inhibition of transcription, GANT61 induces γH2AX foci in S-phase and non-S-phase cells. A transient intra-S-phase checkpoint is induced and cells accumulate in early S without further progression prior to the onset of cell death. The GLI1 target gene FOXM1, and its transcriptional target CDC6, regulate the G1/S transition and initiation of DNA replication, and are decreased in GANT61-treated cells. Data suggest that: 1) GANT61 inhibits GLI-mediated transcription by direct binding to GLI; 2) GLI-dependent Pol II transcription is stalled at early elongation in GANT61-treated cells, with formation of R-loops and DNA DSBs; 3) GLI1, FOXM1 and CDC6 regulate events at G1/S and initiation of DNA replication that controls outcome of the GANT61 response. These studies open the door to exploring the role of GLI as a therapeutic target. Since dysregulated HH signaling occurs in a wide variety of human cancers, the proposed studies are of broad impact.

Citation Format: Akwasi Agyeman, Babal K. Jha, Tapati Mazumder, Janet A. Houghton. Targeting GLI-dependent transcription by GANT61 in human colon carcinoma cells (CC); a new therapeutic approach. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1759. doi:10.1158/1538-7445.AM2014-1759

Ribonuclease L and metal-ion-independent endoribonuclease cleavage sites in host and viral RNAs

Ribonuclease L (RNase L) is a metal-ion–independent endoribonuclease associated with antiviral and antibacterial defense, cancer and lifespan. Despite the biological significance of RNase L, the RNAs cleaved by this enzyme are poorly defined. In this study, we used deep sequencing methods to reveal the frequency and location of RNase L cleavage sites within host and viral RNAs. To make cDNA libraries, we exploited the 2′, 3′-cyclic phosphate at the end of RNA fragments produced by RNase L and other metal-ion–independent endoribonucleases. We optimized and validated 2′, 3′-cyclic phosphate cDNA synthesis and Illumina sequencing methods using viral RNAs cleaved with purified RNase L, viral RNAs cleaved with purified RNase A and RNA from uninfected and poliovirus-infected HeLa cells. Using these methods, we identified (i) discrete regions of hepatitis C virus and poliovirus RNA genomes that were profoundly susceptible to RNase L and other single-strand specific endoribonucleases, (ii) RNase L-dependent and RNase L-independent cleavage sites within ribosomal RNAs (rRNAs) and (iii) 2′, 3′-cyclic phosphates at the ends of 5S rRNA and U6 snRNA. Monitoring the frequency and location of metal-ion–independent endoribonuclease cleavage sites within host and viral RNAs reveals, in part, how these enzymes contribute to health and disease.

Molecular identification of dermatophytosis by polymerase chain reaction (PCR) and detection of source of infection by restricted fragment length polymorphism (RFLP)

Introduction Dermatophytes are responsible for most superficial fungal infections and the estimated lifetime risk of acquiring a dermatophyte infection is between 10-20%. These fungi are mainly classified in three major genera Microsporum, Trichophyton and Epidermophyton. Materials and Methods Clinically suspected 200 cases of dermatophyte infected patients from K. R. Hospital Mysore and Mission Hospital Mysore were included in this descriptive study from January 2011 to June 2012. All the culture positive smear- 10% Potassium Hydroxide (KOH) and culture in different dermatophytic medium patients were confirmed by PCR and source of infection was detected (n=10) from PCR positive patients and (n=10) from their domestic animals by PCR-RFLP methods targeting 18S rDNA regions of fungi. Results Out of 200 clinically suspected cases KOH mount was positive in 143 (71.5%) cases and culture was positive in 132(66%) cases. The isolates belonged to three genera and eight species as T.mentagrophytes 52(39.4%), T.rubrum 30(22.7%), T.violacium 18(13.6%), T.verrucosum 11(8.3%), E.floccosum 10(7.6%), M.canis 6(4.5%), T.tonsurans 03(2.3%) and T.schollenii 2(1.5%). To identify the source of infection 10 animals ,one each from the houses of 10 patients who were PCR positive were also subjected to PCR and RFLP. The animals and the patients were found to be infected by same organisms T.verrucosum .This indicates that T.verrucosum infection is from animal source. Conclusion Dermatophytic infections are more common infectious disease. Preliminary diagnosis of dermatophytosis can be done by KOH mount and culture, which takes longer time to report and cannot differentiate at the genus and species level. Results indicate that PCR-RFLP may be considered as gold standard for the diagnosis and confirmation of source of infection of dermatophytosis and can aid the clinician in initiating prompt and appropriate antifungal therapy. Journal of College of Medical Sciences-Nepal, 2012, Vol-8, No-4, 7-15 DOI: http://dx.doi.org/10.3126/jcmsn.v8i4.8694

Suppression of antiviral innate immunity by sunitinib enhances oncolytic virotherapy

The use of lytic viruses to preferentially infect and eliminate cancer cells while sparing normal cells is a promising experimental therapeutic approach for treating cancer. However, the efficacy of oncolytic virotherapy is often limited by two innate immunity pathways, the protein kinase PKR and the 2'-5'-oligoadenylate (OAS)/RNase L systems, which are widely present in many but not all tumor cell types. Previously, we reported that the anticancer drug, sunitinib, an inhibitor of VEGF-R and PDGF-R, has off-target effects against both PKR and RNase L. Here we show that combining sunitinib treatments with infection by an oncolytic virus, vesicular stomatitis virus (VSV), led to the elimination of prostate, breast, and kidney malignant tumors in mice. In contrast, either virus or sunitinib alone slowed tumor progression but did not eliminate tumors. In prostate tumors excised from treated mice, sunitinib decreased levels of the phosphorylated form of translation initiation factor, eIF2-α, a substrate of PKR, by 10-fold while increasing median viral titers by 23-fold. The sunitinib/VSV regimen caused complete and sustained tumor regression in both immunodeficient and immunocompetent animals. Results indicate that transient inhibition of innate immunity with sunitinib enhances oncolytic virotherapy allowing the recovery of tumor-bearing animals.

Assessment of district health system within inter-sectoral context in Nepal

BACKGROUND

Inter-sectoral coordination has been one of the different factors in the district health system that produces efficient output which has been identified by the Alma Ata declaration as an essential component to achieve notion of 'Health for All'. This study was therefore aimed to describe the major four key functions of the health systems and to find out the situation of inter-sectoral coordination in Nepal.

METHODS

A mixed method with Focus Group Discussion (FGD) and In-Depth Interview with relevant personnel to collect the majority of the data was carried out from June 2012 to November 2012 from six districts selected purposively based on the health performance indicators.

RESULTS

The major findings in relation to the key functions of district health systems showed that the overall management of the district health system happens under the leadership of chief of District Health Office of Public health office with the cooperation of all the personnel in different sections in a predetermined pattern and inter-sectoral coordination and collaboration exist only to a very limited extent.

CONCLUSIONS

The major constraints for inter-sectoral coordination to be effective is lack of its planning and enforcement where inter-sectoral coordination could be important for both preventive and promotive health care, waste management, water supply and sanitation, health service utilization, pesticides and human health, agriculture and nutrition, air pollution. The main components in the district health system needs an immediate attention and inter-sectoral effort should be initiated from the central level and implemented in all the levels.

Phosphoinositide 3-kinase γ inhibits cardiac GSK-3 independently of Akt

Activation of cardiac phosphoinositide 3-kinase α (PI3Kα) by growth factors, such as insulin, or activation of PI3Kγ downstream of heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors stimulates the activity of the kinase Akt, which phosphorylates and inhibits glycogen synthase kinase-3 (GSK-3). We found that PI3Kγ inhibited GSK-3 independently of the insulin-PI3Kα-Akt axis. Although insulin treatment activated Akt in PI3Kγ knockout mice, phosphorylation of GSK-3 was decreased compared to control mice. GSK-3 is activated when dephosphorylated by the protein phosphatase 2A (PP2A), which is activated when methylated by the PP2A methyltransferase PPMT-1. PI3Kγ knockout mice showed increased activity of PPMT-1 and PP2A and enhanced nuclear export of the GSK-3 substrate NFATc3. GSK-3 inhibits cardiac hypertrophy, and the hearts of PI3Kγ knockout mice were smaller compared to those of wild-type mice. Cardiac overexpression of a catalytically inactive PI3Kγ (PI3Kγ(inact)) transgene in PI3Kγ knockout mice reduced the activities of PPMT-1 and PP2A and increased phosphorylation of GSK-3. Furthermore, PI3Kγ knockout mice expressing the PI3Kγ(inact) transgene had larger hearts than wild-type or PI3Kγ knockout mice. Our studies show that a kinase-independent function of PI3Kγ could directly inhibit GSK-3 function by preventing the PP2A-PPMT-1 interaction and that this inhibition of GSK-3 was independent of Akt.

Antagonism of the interferon-induced OAS-RNase L pathway by murine coronavirus ns2 protein is required for virus replication and liver pathology

Many viruses induce hepatitis in humans, highlighting the need to understand the underlying mechanisms of virus-induced liver pathology. The murine coronavirus, mouse hepatitis virus (MHV), causes acute hepatitis in its natural host and provides a useful model for understanding virus interaction with liver cells. The MHV accessory protein, ns2, antagonizes the type I interferon response and promotes hepatitis. We show that ns2 has 2′,5′-phosphodiesterase activity, which blocks the interferon inducible 2′,5′-oligoadenylate synthetase (OAS)-RNase L pathway to facilitate hepatitis development. Ns2 cleaves 2′,5′-oligoadenylate, the product of OAS, to prevent activation of the cellular endoribonuclease RNase L and consequently block viral RNA degradation. An ns2 mutant virus was unable to replicate in the liver or induce hepatitis in wild-type mice, but was highly pathogenic in RNase L deficient mice. Thus, RNase L is a critical cellular factor for protection against viral infection of the liver and the resulting hepatitis.

Septicemia detection by blood buffy coat smear in primary health care centers

Early diagnosis of childhood septicemia can be done by simple tests like C-reactive protein (CRP) and anticoagulant added blood centrifuged buffy coat smear (BBCS) examination, where there is no well equipped hospital setting for blood culture and identification facility in remote health care centers. This study was conducted between 1st Jan. 2007 to 27th Dec. 2007 in College of Medical Sciences, Bharatpur, Nepal. In this study we have selected 150 suspected cases of childhood septicemia for screening CRP by kit method and BBCS by two slide techniques. This kit is supplied by Span Diagnostic Pvt. Ltd. (Surat, India). Out of 150 cases of childhood septicemia of age group 0-14 years, 83 had positive C- reactive protein (CRP >6ì g/ml), 70 were positive for BBCS and blood culture was positive only in 83 cases, where predominant organism being Klebsiella species followed by Staphylococcus species. CRP test showed 100.0% sensitivity and 87.30% specificity, where BBCS showed 76.5% sensitivity and 91.2% specificity. Blood culture reports are available only after 48-72 hours and this facility is available only in well equipped centers but CRP and BBCS are easy and cheap procedure to perform even in remote areas for early diagnosis of childhood septicemia. DOI: http://dx.doi.org/10.3126/jcmsn.v7i1.5968 JCMSN 2011; 7(1): 19-23

Assessment of medical and health institutions registered as research centres in Nepal

BACKGROUND

There were several reports in the various mass media regarding misuse of the word "research" by various organization and it has been argued that putting the word "Research" in any agency's name made easier to get the various medical from abroad without paying or paying minimum or discounted government tax than others. The objectives of the study was to find out the status Medical and Health institutions designated as Research Centres in Nepal.

METHODS

A cross sectional prospective study was carried in medical and health institutions of Nepal. Data regarding the registration of institutions/organizations having the word "research" in its name were collected from concerned registered organizations. Formative evaluation method was adopted in which information were added continuously, organized systematically and analysed periodically during the evaluation period.

RESULTS

There were altogether 370 health related research centers registered in MoI and CDO at the district level till 31 December 2010. These research centers were located in 33 districts of Nepal. Among these there were 65 (82%) health facilities and 305 (18%) NGOs designated as research centers. The region wise the range of number of research centers among five regions was 4 to 283. The highest number of research centers level. The highest number of research centers was found in Kathmandu district. Out of 370 research centers, 85 research centers (72 from among health facility related research centers and 13 from among NGO related research centers) were selected randomly for evaluation purpose, which represented 23 percent of sample selection. The sample selection was not less than 20 percent in each category of research centers. One fifth research centers were found to conduct health related research progam. Among which majority (more than 50%) of NGO related research centers was found to conduct health research. There were few (14%) health facility related research centers that actually conducted health related research program. The study also shows that majority 73 (86%) of the research centers didn't start the research yet.

CONCLUSIONS

Forty percent of the research centers in Nepal didn't know the actual reason for putting the word "research" into their signboard. A regulation has to be made to safeguard and maintain the integrity of research in Nepal.

Effectiveness and efficiency of Aama Surakshya Karyakram in terms of barriers in accessing maternal health services in Nepal

BACKGROUND

The Family Health Division along with the MoHP developed a policy that recommended provision of incentives to all delivering mother by removing the parity condition and termed Safe Delivery Incentive Programme (SDIP) to make it more appropriate. The SDIP was branded as AamaSurakshyaKaryakram (ASK). The main objective of the study was to find out the effectiveness and efficiency of AamaSurakshyaKaryakram to address barrier in accessing maternal health services in Nepal.

METHODS

An exploratory and cross sectional descriptive study was conducted by quantitative and qualitative tools and techniques. To provide comprehensive coverage, five districts have been selected representing four development (eastern, central, western and far-western) and three (mountain, hill and flat) ecological region were selected.

RESULTS

Out of 47 exit client interviews conducted in this study, 51 percent were done in Sunsari, followed by Sarlahi (17%), Dadeldhura (17%), and Arghakhanchi (15%). Most of these mothers (94%) delivered their children in the hospitals, and rest (6%) in PHCCs. Sixty percent mothers were in the age group of 20-25 years, while 45 percent were from Tarai/Madhesi group followed by Brahmins/Chhetries group (34%). Total 70% mothers were found to be literate. 55% mothers were found to be visiting health facilities during labour pain. 2% mothers were visiting heath facilities before labour pain started. Rest mothers were visiting health facilities after one or two days of labour pain. Total 70% mothers were able to reach the health facility within 60 minutes, while 13 percent mothers were able to reach the facility more than 3 hours, and 17% were in between. All mothers who visited PHCCs were able to reach the facility within 60 minutes while analyzing health facility-wise.

CONCLUSIONS

Mothers delivered at home as they were not well prepared to go to health facility. Lack of transportation facility hindered for institutional delivery. None of them figured out that there was a provision of transport incentive; they only knew that there was a cash payment, but they didn't know exactly for what specific purpose mothers were receiving such payments. Ask found to be effective and efficient in order to address barriers occurring inside the health facility and financial barrier except geo-graphical barrier in accessing maternal health services in Nepal.

Nucleoside modifications in RNA limit activation of 2'-5'-oligoadenylate synthetase and increase resistance to cleavage by RNase L

The interferon-induced enzymes 2′-5′-oligoadenylate synthetase (OAS) and RNase L are key components of innate immunity involved in sensory and effector functions following viral infections. Upon binding target RNA, OAS is activated to produce 2′-5′-linked oligoadenylates (2-5A) that activate RNase L, which then cleaves single-stranded self and non-self RNA. Modified nucleosides that are present in cellular transcripts have been shown to suppress activation of several RNA sensors. Here, we demonstrate that in vitro transcribed, unmodified RNA activates OAS, induces RNase L-mediated ribosomal RNA (rRNA) cleavage and is rapidly cleaved by RNase L. In contrast, RNA containing modified nucleosides activates OAS less efficiently and induces limited rRNA cleavage. Nucleoside modifications also make RNA resistant to cleavage by RNase L. Examining translation in RNase L^−/− cells and mice confirmed that RNase L activity reduces translation of unmodified mRNA, which is not observed with modified mRNA. Additionally, mRNA containing the nucleoside modification pseudouridine is translated longer and has an extended half-life. The observation that modified nucleosides in RNA reduce 2-5A pathway activation joins OAS and RNase L to the list of RNA sensors and effectors whose functions are limited when RNA is modified, confirming the role of nucleoside modifications in suppressing immune recognition of RNA.

Prevalence of methicillin resistant Staphylococcus aureus (MRSA) among skin infection cases at a hospital in Chitwan, Nepal

This study was carried out to see the methicillin resistance of Staphylococcus aureus isolated from patients with skin and soft tissue infection. In this study, a total of 600 S. aureus isolates isolated from 1,334 specimens from skin and soft tissue infection were included. For the screening of methicillin resistant of S. aureus (MRSA), specimens were inoculated on lipovitellin mannitol salt agar (LMSA) and MRSA were screened by testing resistance to oxacillin in AST plate following the standard bacteriological technique. The overall prevalence of MRSA was 68.0% (408/600). MRSA infection was higher among patients above 30 years of age. Tibeto-Burmans had high MRSA infection rate (72.5%) than Indo-Aryans (56.8%) and the rate was significantly higher among males (75.0%) than females (63.4%) (p<0.05). MRSA isolation rate was higher from wound (76.9%), followed by purulent exudates (67.7%) and abscesses (64.1%). The high prevalence of MRSA found in this study might be due to hospital based specimen.

The Flvr-encoded murine oligoadenylate synthetase 1b (Oas1b) suppresses 2-5A synthesis in intact cells

Resistance to flavivirus-induced disease in mice is conferred by the autosomal gene Flv, identified as 2'-5' oligoadenylate synthetase 1b (Oas1b). Resistant mice express a full-length Oas1b protein while susceptible mice express the truncated Oas1btr. In this study, Oas1b was shown to be an inactive synthetase. Although the Oas/RNase L pathway was previously shown to have an antiviral role during flavivirus infections, Oas1b protein inhibited Oas1a in vitro synthetase activity in a dose-dependent manner and reduced 2-5A production in vivo in response to poly(I:C). These findings suggest that negative regulation of 2-5A by inactive Oas1 proteins may fine tune the RNase L response that if not tightly controlled could cause significant damage in cells. The results also indicate that flavivirus resistance conferred by Oas1b is not mediated by 2-5A. Instead, Oas1b inhibits flavivirus replication by an alternative mechanism that overrides the proviral effect of reducing 2-5A accumulation and RNase L activation.

Prevalence of asymptomatic bacteriuria among elderly diabetic patients residing in Chitwan

BACKGROUND

A retrospective study was done on Asymptomatic Bacteriuria (ASB), among elderly diabetic patients residing in Chitwan, Nepal from 1st January 2006 to 12th December 2006. Diabetic patients above 40 years of age were included in this study where as below 40 years of age group were excluded.

OBJECTIVE

To study the prevalence of ASB among elderly diabetic patients for the Bacteriological profile and their antibiotic susceptibility pattern.

MATERIALS AND METHODS

Urine sample was collected from 636 diabetic patients above 40 years age attending College of Medical Sciences Teaching Hospital for regular blood sugar estimation. Culture and Antibiotic susceptibility test (AST) were performed using standard microbiological technique. ASB was determined as presence of > 105(5) bacteria/ml in a culture of urine sample.

RESULTS

The prevalence of ASB among diabetic patients in Bharatpur was found to be 9.43% (12.07% in females and 5.08% in males). The most common bacterial isolate was Escherichia coli (41.66%). Nitrofurantoin, Cefotaxime and Chloramphenicol were the most effective drugs for the majority of isolates.

CONCLUSION

The study shows necessity of regular urine culture to detect ASB, along with blood sugar estimation for diabetic patients to prevent them from further complications due to it.

A putative loop E motif and an H-H kissing loop interaction are conserved and functional features in a group C enterovirus RNA that inhibits ribonuclease L

A phylogenetically conserved RNA structure within the open reading frame of poliovirus and other group C enteroviruses functions as a competitive inhibitor of the antiviral endoribonuclease RNase L. Hence, we call this viral RNA the RNase L competitive inhibitor RNA (RNase L ciRNA). In this investigation we used phylogenetic information, RNA structure prediction software, site-directed mutagenesis, and RNase L activity assays to identify functionally important sequences and structures of the RNase L ciRNA. A putative loop E motif is phylogenetically conserved in the RNA structure and mutations of nucleotides within the putative loop E motif destroyed the ability of the RNA molecule to inhibit RNase L. A putative H-H kissing loop interaction is phylogenetically conserved in the RNA structure and covariant polymorphisms that maintain the Watson-Crick complementarity required for the kissing interaction provide evidence of its importance. Compensatory mutations that disrupted and then restored the putative kissing interaction confirm that it contributes to the ability of the viral RNA to inhibit RNase L. RNase L was activated late during the course of poliovirus replication in HeLa cells, as virus replication and assembly neared completion. We conclude that a putative loop E motif and an H-H kissing loop interaction are key features of the group C enterovirus RNA associated with the inhibition of RNase L.

A viral RNA competitively inhibits the antiviral endoribonuclease domain of RNase L

Ribonuclease L (RNase L) is a latent endoribonuclease in an evolutionarily ancient interferon-regulated dsRNA-activated antiviral pathway. 2'-5' oligoadenylate (2-5A), the product of dsRNA-activated oligoadenylate synthetases (OASes), binds to ankyrin repeats near the amino terminus of RNase L, initiating a series of conformational changes that result in the activation of the endoribonuclease. A phylogenetically conserved RNA structure within group C enteroviruses inhibits the endoribonuclease activity of RNase L. In this study we report the mechanism by which group C enterovirus RNA inhibits RNase L. Viral RNA did not affect 2-5A binding to RNase L. Rather, the viral RNA inhibited the endoribonuclease domain. We used purified RNase L, purified 2-5A, and an RNA substrate with a 5' fluorophore and 3' quencher in FRET assays to measure inhibition of RNase L activity by the viral RNA. The group C enterovirus RNA was a competitive inhibitor of the endoribonuclease with a K(i) of 34 nM. Consistent with the kinetic profile of a competitive inhibitor, the viral RNA inhibited the constitutively active endoribonuclease domain of RNase L. We call this viral RNA the RNase L competitive inhibitor RNA (RNase L ciRNA).

Prevalence of asymptomatic bacteriuria in school going children in Pokhara valley

OBJECTIVES

There were mainly two objectives of the study. One was to detect bacteriuria in school going children in Pokhara valley and the other was to identify the causative organisms in various age groups in children.

MATERIALS AND METHODS

This study was carried out in the Microbiology laboratory of The School of Pharmaceutical and Biomedical Sciences, Simalchaur, Pokhara University, Nepal. A total of 502 urine samples of 5 to 13 years children from different schools of Pokhara valley were screened to see asymptomatic bacteriuria during January 2005 to June 2005. A sterile wide mouth container was given to each student to collect mid-stream urine samples. All the urine samples were transported to the Microbiology laboratory within half an hour to one hour. The samples were processed for microscopical examination to observe for turbidity and the presence of protein and sugar by dipstick method, microscopical examination to see pus cells, RBCs, epithelial cells, casts and crystals, culture of urine samples on Blood agar and MacConkey agar to identify the potential pathogens. The antibiotic sensitivity test was performed for those bacteria which were grown on culture. The colony count was evaluated and organisms were identified by biochemical tests.

RESULT

Out of 502 samples, 7(1.39%) samples grew the bacterial pathogens that are responsible to cause urinary tract infection. Among them Escherichia coli 4(57.14%) was the predominant bacterial pathogen.

CONCLUSION

Study of asymptomatic bacteriuria is important as found in the present study in which Escherichia coli was the most frequently incriminated as the causative agents.

Role of 2-5A-dependent RNase-L in senescence and longevity

Senescence is a permanent growth arrest that restricts the lifespan of primary cells in culture, and represents an in vitro model for aging. Senescence functions as a tumor suppressor mechanism that can be induced independent of replicative crisis by diverse stress stimuli. RNase-L mediates antiproliferative activities and functions as a tumor suppressor in prostate cancer, therefore, we examined a role for RNase-L in cellular senescence and aging. Ectopic expression of RNase-L induced a senescent morphology, a decrease in DNA synthesis, an increase in senescence-associated beta-galactosidase activity, and accelerated replicative senescence. In contrast, senescence was retarded in RNase-L-null fibroblasts compared with wild-type fibroblasts. Activation of endogenous RNase-L by 2-5A transfection induced distinct senescent and apoptotic responses in parental and Simian virus 40-transformed WI38 fibroblasts, respectively, demonstrating cell type specific differences in the antiproliferative response to RNase-L activation. Replicative senescence is a model for in vivo aging; therefore, genetic disruption of senescence effectors may impact lifespan. RNase-L-/- mice survived 31.7% (P<0.0001) longer than strain-matched RNase-L+/+ mice providing evidence for a physiological role for RNase-L in aging. These findings identify a novel role for RNase-L in senescence that may contribute to its tumor suppressive function and to the enhanced longevity of RNase-L-/- mice.