Medical Biology - Research Publications
Now showing items 1-12 of 186
Cytokine signatures of Plasmodium vivax infection during pregnancy and delivery outcomes.
(Public Library of Science (PLoS), 2020-05)
Plasmodium vivax malaria is a neglected disease, particularly during pregnancy. Severe vivax malaria is associated with inflammatory responses but in pregnancy immune alterations make it uncertain as to what cytokine signatures predominate, and how the type and quantity of blood immune mediators influence delivery outcomes. We measured the plasma concentrations of a set of thirty-one biomarkers, comprising cytokines, chemokines and growth factors, in 987 plasma samples from a cohort of 572 pregnant women from five malaria-endemic tropical countries and related these concentrations to delivery outcomes (birth weight and hemoglobin levels) and malaria infection. Samples were collected at recruitment (first antenatal visit) and at delivery (periphery, cord and placenta). At recruitment, we found that P. vivax-infected pregnant women had higher plasma concentrations of proinflammatory (IL-6, IL-1β, CCL4, CCL2, CXCL10) and TH1-related cytokines (mainly IL-12) than uninfected women. This biomarker signature was essentially lost at delivery and was not associated with birth weight nor hemoglobin levels. Antiinflammatory cytokines (IL-10) were positively associated with infection and poor delivery outcomes. CCL11 was the only biomarker to show a negative association with P. vivax infection and its concentration at recruitment was positively associated with hemoglobin levels at delivery. Birth weight was negatively associated with peripheral IL-4 levels at delivery. Our multi-biomarker multicenter study is the first comprehensive one to characterize the immunological signature of P. vivax infection in pregnancy thus far. In conclusion, data show that while TH1 and pro-inflammatory responses are dominant during P. vivax infection in pregnancy, antiinflammatory cytokines may compensate excessive inflammation avoiding poor delivery outcomes, and skewness toward a TH2 response may trigger worse delivery outcomes. CCL11, a chemokine largely neglected in the field of malaria, emerges as an important marker of exposure or mediator in this condition.
Cotargeting BCL-2 and MCL-1 in high-risk B-ALL
(AMER SOC HEMATOLOGY, 2020-06-23)
Improving survival outcomes in adult B-cell acute lymphoblastic leukemia (B-ALL) remains a clinical challenge. Relapsed disease has a poor prognosis despite the use of tyrosine kinase inhibitors (TKIs) for Philadelphia chromosome positive (Ph+ ALL) cases and immunotherapeutic approaches, including blinatumomab and chimeric antigen receptor T cells. Targeting aberrant cell survival pathways with selective small molecule BH3-mimetic inhibitors of BCL-2 (venetoclax, S55746), BCL-XL (A1331852), or MCL1 (S63845) is an emerging therapeutic option. We report that combined targeting of BCL-2 and MCL1 is synergistic in B-ALL in vitro. The combination demonstrated greater efficacy than standard chemotherapeutics and TKIs in primary samples from adult B-ALL with Ph+ ALL, Ph-like ALL, and other B-ALL. Moreover, combined BCL-2 or MCL1 inhibition with dasatinib showed potent killing in primary Ph+ B-ALL cases, but the BH3-mimetic combination appeared superior in vitro in a variety of Ph-like ALL samples. In PDX models, combined BCL-2 and MCL1 targeting eradicated ALL from Ph- and Ph+ B-ALL cases, although fatal tumor lysis was observed in some instances of high tumor burden. We conclude that a dual BH3-mimetic approach is highly effective in diverse models of high-risk human B-ALL and warrants assessment in clinical trials that incorporate tumor lysis precautions.
Impact of elevated anti-apoptotic MCL-1 and BCL-2 on the development and treatment of MLL-AF9 AML in mice
(NATURE PUBLISHING GROUP, 2019-07-01)
Many acute myeloid leukaemias (AMLs) express high levels of BCL-2 and MCL-1, especially after therapy. To test the impact of these anti-apoptotic proteins on AML development and treatment, we used haemopoietic reconstitution to generate MLL-AF9 AMLs expressing BCL-2 or Mcl-1 transgenes. AMLs with elevated BCL-2 or MCL-1 had a higher proportion of mature myeloid cells but, like conventional MLL-AF9 AMLs, were readily transplantable. Short-term cell lines established from multiple primary AMLs of each genotype were tested in vitro for susceptibility to chemotherapeutics currently used for treating AML (daunorubicin, etoposide, cytarabine); the proteasome inhibitor bortezomib; CDK7/9 inhibitors; and BH3 mimetics, which bind and inhibit pro-survival proteins. The BH3 mimetics tested, alone and in combination with the other drugs, were: ABT-737 which, like its clinical counterpart navitoclax, targets BCL-2, BCL-XL and BCL-W; BCL-2-specific ABT-199 (venetoclax); BCL-XL-specific A-1331852; and S63845, a new MCL-1-specific BH3 mimetic. As single agents, daunorubicin and bortezomib had the greatest efficacy. Elevated MCL-1 or BCL-2 reduced sensitivity to daunorubicin but, surprisingly, not to bortezomib. MCL-1 markedly enhanced resistance to ABT-737 and ABT-199 but not S63845, and BCL-2 increased resistance to S63845 but not to ABT-737 or ABT-199. Notable synergies were achieved by combining BH3 mimetics with daunorubicin: S63845 increased the sensitivity of both MCL-1 and BCL-2 overexpressing MLL-AF9 AMLs, and ABT-737 aided in killing those overexpressing BCL-2. Synergy between daunorubicin and ABT-199 was also apparent in vivo, although not curative. Impressive synergistic responses were achieved for human MLL-fusion AML cell lines treated with daunorubicin plus either ABT-737, ABT-199 or S63845, and with ABT-199 plus S63845, with or without daunorubicin. Our data suggest that AML patients may benefit from combining conventional cytotoxic drugs with BH3 mimetics targeting BCL-2 or MCL-1 or, if tolerated, both these agents.
Exome-wide analysis of rare coding variation identifies novel associations with COPD and airflow limitation in MOCS3, IFIT3 and SERPINA12
(BMJ PUBLISHING GROUP, 2016-06-01)
BACKGROUND: Several regions of the genome have shown to be associated with COPD in genome-wide association studies of common variants. OBJECTIVE: To determine rare and potentially functional single nucleotide polymorphisms (SNPs) associated with the risk of COPD and severity of airflow limitation. METHODS: 3226 current or former smokers of European ancestry with lung function measures indicative of Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2 COPD or worse were genotyped using an exome array. An analysis of risk of COPD was carried out using ever smoking controls (n=4784). Associations with %predicted FEV1 were tested in cases. We followed-up signals of interest (p<10(-5)) in independent samples from a subset of the UK Biobank population and also undertook a more powerful discovery study by meta-analysing the exome array data and UK Biobank data for variants represented on both arrays. RESULTS: Among the associated variants were two in regions previously unreported for COPD; a low frequency non-synonymous SNP in MOCS3 (rs7269297, pdiscovery=3.08×10(-6), preplication=0.019) and a rare SNP in IFIT3, which emerged in the meta-analysis (rs140549288, pmeta=8.56×10(-6)). In the meta-analysis of % predicted FEV1 in cases, the strongest association was shown for a splice variant in a previously unreported region, SERPINA12 (rs140198372, pmeta=5.72×10(-6)). We also confirmed previously reported associations with COPD risk at MMP12, HHIP, GPR126 and CHRNA5. No associations in novel regions reached a stringent exome-wide significance threshold (p<3.7×10(-7)). CONCLUSIONS: This study identified several associations with the risk of COPD and severity of airflow limitation, including novel regions MOCS3, IFIT3 and SERPINA12, which warrant further study.
Sixteen new lung function signals identified through 1000 Genomes Project reference panel imputation
(Nature Research (part of Springer Nature), 2015-12-01)
Lung function measures are used in the diagnosis of chronic obstructive pulmonary disease. In 38,199 European ancestry individuals, we studied genome-wide association of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC with 1000 Genomes Project (phase 1)-imputed genotypes and followed up top associations in 54,550 Europeans. We identify 14 novel loci (P<5 × 10−8) in or near ENSA, RNU5F-1, KCNS3, AK097794, ASTN2, LHX3, CCDC91, TBX3, TRIP11, RIN3, TEKT5, LTBP4, MN1 and AP1S2, and two novel signals at known loci NPNT and GPR126, providing a basis for new understanding of the genetic determinants of these traits and pulmonary diseases in which they are altered.
A novel metabarcoding diagnostic tool to explore protozoan haemoparasite diversity in mammals: a proof-of-concept study using canines from the tropics
(NATURE PUBLISHING GROUP, 2019-09-02)
Haemoparasites are responsible for some of the most prevalent and debilitating canine illnesses across the globe, whilst also posing a significant zoonotic risk to humankind. Nowhere are the effects of such parasites more pronounced than in developing countries in the tropics where the abundance and diversity of ectoparasites that transmit these pathogens reaches its zenith. Here we describe the use of a novel next-generation sequencing (NGS) metabarcoding based approach to screen for a range of blood-borne apicomplexan and kinetoplastid parasites from populations of temple dogs in Bangkok, Thailand. Our methodology elucidated high rates of Hepatozoon canis and Babesia vogeli infection, whilst also being able to characterise co-infections. In addition, our approach was confirmed to be more sensitive than conventional endpoint PCR diagnostic methods. Two kinetoplastid infections were also detected, including one by Trypanosoma evansi, a pathogen that is rarely screened for in dogs and another by Parabodo caudatus, a poorly documented organism that has been previously reported inhabiting the urinary tract of a dog with haematuria. Such results demonstrate the power of NGS methodologies to unearth rare and unusual pathogens, especially in regions of the world where limited information on canine vector-borne haemoparasites exist.
EGFRvIII-mediated transactivation of receptor tyrosine kinases in glioma: mechanism and therapeutic implications
(NATURE PUBLISHING GROUP, 2015-10-01)
A truncation mutant of the epidermal growth factor receptor, EGFRvIII, is commonly expressed in glioma, an incurable brain cancer. EGFRvIII is tumorigenic, in part, through its transactivation of other receptor tyrosine kinases (RTKs). Preventing the effects of this transactivation could form part of an effective therapy for glioma; however, the mechanism by which the transactivation occurs is unknown. Focusing on the RTK MET, we show that MET transactivation in U87MG human glioma cells in vitro is proportional to EGFRvIII activity and involves MET heterodimerization associated with a focal adhesion kinase (FAK) scaffold. The transactivation of certain other RTKs was, however, independent of FAK. Simultaneously targeting EGFRvIII (with panitumumab) and the transactivated RTKs themselves (with motesanib) in an intracranial mouse model of glioma resulted in significantly greater survival than with either agent alone, indicating that cotargeting these RTKs has potent antitumor efficacy and providing a strategy for treating EGFRvIII-expressing gliomas, which are usually refractory to treatment.
Unique properties of a subset of human pluripotent stem cells with high capacity for self-renewal
(NATURE PUBLISHING GROUP, 2020-05-15)
Archetypal human pluripotent stem cells (hPSC) are widely considered to be equivalent in developmental status to mouse epiblast stem cells, which correspond to pluripotent cells at a late post-implantation stage of embryogenesis. Heterogeneity within hPSC cultures complicates this interspecies comparison. Here we show that a subpopulation of archetypal hPSC enriched for high self-renewal capacity (ESR) has distinct properties relative to the bulk of the population, including a cell cycle with a very low G1 fraction and a metabolomic profile that reflects a combination of oxidative phosphorylation and glycolysis. ESR cells are pluripotent and capable of differentiation into primordial germ cell-like cells. Global DNA methylation levels in the ESR subpopulation are lower than those in mouse epiblast stem cells. Chromatin accessibility analysis revealed a unique set of open chromatin sites in ESR cells. RNA-seq at the subpopulation and single cell levels shows that, unlike mouse epiblast stem cells, the ESR subset of hPSC displays no lineage priming, and that it can be clearly distinguished from gastrulating and extraembryonic cell populations in the primate embryo. ESR hPSC correspond to an earlier stage of post-implantation development than mouse epiblast stem cells.
An Erg-driven transcriptional program controls B cell lymphopoiesis.
(Nature Research (part of Springer Nature), 2020-06-15)
B lymphoid development is initiated by the differentiation of hematopoietic stem cells into lineage committed progenitors, ultimately generating mature B cells. This highly regulated process generates clonal immunological diversity via recombination of immunoglobulin V, D and J gene segments. While several transcription factors that control B cell development and V(D)J recombination have been defined, how these processes are initiated and coordinated into a precise regulatory network remains poorly understood. Here, we show that the transcription factor ETS Related Gene (Erg) is essential for early B lymphoid differentiation. Erg initiates a transcriptional network involving the B cell lineage defining genes, Ebf1 and Pax5, which directly promotes expression of key genes involved in V(D)J recombination and formation of the B cell receptor. Complementation of Erg deficiency with a productively rearranged immunoglobulin gene rescued B lineage development, demonstrating that Erg is an essential and stage-specific regulator of the gene regulatory network controlling B lymphopoiesis.
Targeting platelets for improved outcome in KRAS-driven lung adenocarcinoma.
(Springer Nature, 2020-06-13)
Elevated platelet count is associated with poor survival in certain solid cancers, including lung cancer. In addition, experimental transplantation of cancer cell lines has uncovered a role for platelets in blood-borne metastasis. These studies, however, do not account for heterogeneity between lung cancer subtypes. Subsequently, the role of platelets in the major subtypes of non-small cell lung cancer (adenocarcinoma (ADC) and squamous cell carcinoma (SqCC)) is not fully understood. We utilised an autochthonous KrasLSL-G12D/+;p53flox/flox mouse model of lung ADC together with genetic models of thrombocytopenia to interrogate the role of platelets in lung cancer growth and progression. While thrombocytopenia failed to impact primary tumour growth, in experimental metastatic models however, thrombocytopenic mice displayed significantly extended survival. Utilising a novel thrombocytopenic immunocompromised mouse, the importance of platelets in metastatic dissemination was confirmed with human KRAS-mutant ADC cell lines. Finally, retrospective analysis of a NSCLC patient cohort revealed thrombocytosis was predictive of poor survival in ADC patients with metastatic disease. Interestingly, this association was not apparent in SqCC patients. Overall, these data highlight the possibility of patient stratification using thrombocytosis as a biomarker, and indicates opportunities for potential novel treatment strategies that combine anti-platelet and lung cancer therapies.
CX-5461 activates the DNA damage response and demonstrates therapeutic efficacy in high-grade serous ovarian cancer
(NATURE PUBLISHING GROUP, 2020-05-26)
Acquired resistance to PARP inhibitors (PARPi) is a major challenge for the clinical management of high grade serous ovarian cancer (HGSOC). Here, we demonstrate CX-5461, the first-in-class inhibitor of RNA polymerase I transcription of ribosomal RNA genes (rDNA), induces replication stress and activates the DNA damage response. CX-5461 co-operates with PARPi in exacerbating replication stress and enhances therapeutic efficacy against homologous recombination (HR) DNA repair-deficient HGSOC-patient-derived xenograft (PDX) in vivo. We demonstrate CX-5461 has a different sensitivity spectrum to PARPi involving MRE11-dependent degradation of replication forks. Importantly, CX-5461 exhibits in vivo single agent efficacy in a HGSOC-PDX with reduced sensitivity to PARPi by overcoming replication fork protection. Further, we identify CX-5461-sensitivity gene expression signatures in primary and relapsed HGSOC. We propose CX-5461 is a promising therapy in combination with PARPi in HR-deficient HGSOC and also as a single agent for the treatment of relapsed disease.
Regulation of PRMT5-MDM4 axis is critical in the response to CDK4/6 inhibitors in melanoma
(NATL ACAD SCIENCES, 2019-09-03)
Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are an established treatment in estrogen receptor-positive breast cancer and are currently in clinical development in melanoma, a tumor that exhibits high rates of CDK4 activation. We analyzed melanoma cells with acquired resistance to the CDK4/6 inhibitor palbociclib and demonstrate that the activity of PRMT5, a protein arginine methyltransferase and indirect target of CDK4, is essential for CDK4/6 inhibitor sensitivity. By indirectly suppressing PRMT5 activity, palbociclib alters the pre-mRNA splicing of MDM4, a negative regulator of p53, leading to decreased MDM4 protein expression and subsequent p53 activation. In turn, p53 induces p21, leading to inhibition of CDK2, the main kinase substituting for CDK4/6 and a key driver of resistance to palbociclib. Loss of the ability of palbociclib to regulate the PRMT5-MDM4 axis leads to resistance. Importantly, combining palbociclib with the PRMT5 inhibitor GSK3326595 enhances the efficacy of palbociclib in treating naive and resistant models and also delays the emergence of resistance. Our studies have uncovered a mechanism of action of CDK4/6 inhibitors in regulating the MDM4 oncogene and the tumor suppressor, p53. Furthermore, we have established that palbociclib inhibition of the PRMT5-MDM4 axis is essential for robust melanoma cell sensitivity and provide preclinical evidence that coinhibition of CDK4/6 and PRMT5 is an effective and well-tolerated therapeutic strategy. Overall, our data provide a strong rationale for further investigation of novel combinations of CDK4/6 and PRMT5 inhibitors, not only in melanoma but other tumor types, including breast, pancreatic, and esophageal carcinoma.