Rae-Anne Hardie

Genetic diversity and population structure of the endangered marsupial Sarcophilus harrisii (Tasmanian devil)

The Tasmanian devil (Sarcophilus harrisii) is threatened with extinction because of a contagious cancer known as Devil Facial Tumor Disease. The inability to mount an immune response and to reject these tumors might be caused by a lack of genetic diversity within a dwindling population. Here we report a whole-genome analysis of two animals originating from extreme northwest and southeast Tasmania, the maximal geographic spread, together with the genome from a tumor taken from one of them. A 3.3-Gb de novo assembly of the sequence data from two complementary next-generation sequencing platforms was used to identify 1 million polymorphic genomic positions, roughly one-quarter of the number observed between two genetically distant human genomes. Analysis of 14 complete mitochondrial genomes from current and museum specimens, as well as mitochondrial and nuclear SNP markers in 175 animals, suggests that the observed low genetic diversity in todays population preceded the Devil Facial Tumor Disease disease outbreak by at least 100 y. Using a genetically characterized breeding stock based on the genome sequence will enable preservation of the extant genetic diversity in future Tasmanian devil populations.

Targeting ASCT2-mediated glutamine uptake blocks prostate cancer growth and tumour development

Glutamine is conditionally essential in cancer cells, being utilized as a carbon and nitrogen source for macromolecule production, as well as for anaplerotic reactions fuelling the tricarboxylic acid (TCA) cycle. In this study, we demonstrated that the glutamine transporter ASCT2 (SLC1A5) is highly expressed in prostate cancer patient samples. Using LNCaP and PC‐3 prostate cancer cell lines, we showed that chemical or shRNA‐mediated inhibition of ASCT2 function in vitro decreases glutamine uptake, cell cycle progression through E2F transcription factors, mTORC1 pathway activation and cell growth. Chemical inhibition also reduces basal oxygen consumption and fatty acid synthesis, showing that downstream metabolic function is reliant on ASCT2‐mediated glutamine uptake. Furthermore, shRNA knockdown of ASCT2 in PC‐3 cell xenografts significantly inhibits tumour growth and metastasis in vivo, associated with the down‐regulation of E2F cell cycle pathway proteins. In conclusion, ASCT2‐mediated glutamine uptake is essential for multiple pathways regulating the cell cycle and cell growth, and is therefore a putative therapeutic target in prostate cancer.

Report from the killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop: worldwide variation in the KIR loci and further evidence for the co-evolution of KIR and HLA

The killer immunoglobulin-like receptor (KIR) anthropology component of the 15th International Histocompatibility Workshop (IHIWS) sought to explore worldwide population variation in the KIR loci, and to examine the relationship between KIR genes and their human leukocyte antigen (HLA) ligands. Fifteen laboratories submitted KIR genotype and HLA ligand data in 27 populations from six broad ethnic groups. Data were analyzed for correlations between the frequencies of KIR and their known HLA ligands. In addition, allelic typing was performed for KIR2DL2 and 3DL1 in a subset of populations. Strong and significant correlations were observed between KIR2DL2, 2DL3 genotype frequencies and the frequency of their ligand, HLA-C1. In contrast, only weak associations were seen for 3DL1, 3DS1 and the HLA-Bw4 ligand. Although some aspects of the correlations observed here differ from those reported in other populations, these data provide additional evidence of linked evolutionary histories for some KIR and HLA loci. Investigation of allele-level variation for the B haplotype locus KIR 2DL2 showed that two alleles, *001 and *003, predominate in all populations in this study. Much more allelic variation was observed for the A haplotype locus 3DL1, with several alleles observed at moderate frequencies and extensive variation observed between populations.

Human leukocyte antigen-DQ alleles and haplotypes and their associations with resistance and susceptibility to HIV-1 infection

Objectives:To determine the association of DQ antigens with resistance and susceptibility to HIV-1. Design:Despite repeated exposure to HIV-1, a subset of women in the Pumwani Sex Worker cohort established in Nairobi, Kenya in 1985 have remained HIV-1 negative for at least 3 years and are classified as resistant. Differential susceptibility to HIV-1 infection is associated with HIV-1 specific CD4+ and CD8+ T cell responses. As human leukocyte antigen-DQ antigens present viral peptides to CD4+ cells, we genotyped human leukocyte antigen -DQ alleles for 978 women enrolled in the cohort and performed cross-sectional and longitudinal analyses to identify associations of human leukocyte antigen -DQ with resistance/susceptibility to HIV-1. Methods:DQA1 and DQB1 were genotyped using taxonomy-based sequence analysis. SPSS 13.0 was used to determine associations of DQ alleles/haplotypes with HIV-1 resistance, susceptibility, and seroconversion rates. Results:Several DQB1 alleles and DQ haplotypes were associated with resistance to HIV-1 infection. These included DQB1*050301 (P = 0.055, Odds Ratio = 12.77, 95% Confidence Interval = 1.44–112), DQB1*0603 and DQB1*0609 (P = 0.037, Odds Ratio = 3.25, 95% Confidence Interval = 1.12–9.47), and DQA1*010201–DQB1*0603 (P = 0.044, Odds Ratio = 17.33, 95% Confidence Interval = 1.79–168). Conversely, DQB1*0602 (P = 0.048, Odds Ratio = 0.68, 95% Confidence Interval = 0.44–1.05) and DQA1*010201–DQB1*0602 (P = 0.039, Odds Ratio = 0.64, 95% Confidence Interval = 0.41–1.03) were overrepresented in the HIV-1 infected population. DQA1*0504-DQB1*0201, DQA1*010201–DQB1*0201, DQA1*0402-DQB1*0402 and DQA1*0402-DQB1*030101 genotypes were only found in HIV-1 positive subjects (Odds Ratio = 0.30-0.31, 95% Confidence Interval = 0.03–3.70), and these women seroconverted rapidly. The associations of these DQ alleles and haplotypes with resistance and susceptibility to HIV-1 were independent of the previously reported human leukocyte antigen-DRB*01, human leukocyte antigen A2/6802, and human leukocyte antigen-A*2301. Conclusion:The associations of DQ alleles and haplotypes with resistance and susceptibility to HIV-1 emphasize the importance of human leukocyte antigen-DQ and CD4 in anti-HIV-1 immunity.

A common human leucocyte antigen-DP genotype is associated with resistance to HIV-1 infection in Kenyan sex workers.

Human leucocyte antigen-DP presents peptides to CD4+ T cells and plays an important role in parasitic infections and autoimmune diseases, yet its influence on HIV-1 susceptibility has not been well studied. Here, we report several human leucocyte antigen-DP genotypes associated with HIV-1 susceptibility in Kenyan sex workers. Among these, one common genotype stands out. DPA1*010301 (frequency = 60.4%) was associated with HIV-1 resistance (P = 0.033, odds ratio = 1.585, 95% confidence interval = 1.036–2.425) and slower seroconversion (P = 0.001, log rank = 0.595, 95% confidence interval = 0.433–0.817). The discovery of common human leucocyte antigen-DP genotypes contributing to HIV-1 immunity may help overcome difficulties encountered with highly polymorphic human leucocyte antigens.

Clinical presentation of prostate cancer in black South Africans.

Compared with White Americans, Black American men are at a significant increased risk of presenting with prostate cancer (PCa) and associated mortality, suggesting a link to African‐ancestry. However, PCa status within Africa is largely unknown. We address the clinical presentation of PCa within Black South African men.

Identification of four novel KIR2DL2 alleles and two novel KIR2DL3 alleles in an East African population

We report four novel KIR2DL2 alleles and two novel KIR2DL3 alleles identified from an East African population using sequence-based typing. Sequencing and molecular cloning of exon 4 confirmed that the new 2DL2 alleles were identical to 2DL2*003, except for the following nucleotide differences: 2DL2*00601 had a difference at codon 16 (CGC→CCC), resulting in a coding change from arginine to proline; 2DL2*00602 also had this difference at codon 16, as well as a synonymous difference (GAT→GAC) at codon 31; 2DL2*00303 had a synonymous difference (AAA→AAG) at codon 61; and 2DL2*00304 had a synonymous difference (GGG→GGA) at codon 75. 2DL3*017 was identical to 2DL3*005 except at codon 11 (CGG→CTG, arginine→leucine) and exon 9, codons 297 (CAC→CGC, histidine→arginine) and 321 (TGA→AGA, stop codon→arginine). 2DL3*00104 was identical to KIR2DL3*001 except for a synonymous difference (GAG→GAA) at codon 54. Identification of novel killer cell immunoglobulin-like receptor (KIR) alleles is a testament to the genetic diversity in this population.

Mitochondrial mutations and metabolic adaptation in pancreatic cancer

BackgroundPancreatic cancer has a five-year survival rate of ~8%, with characteristic molecular heterogeneity and restricted treatment options. Targeting metabolism has emerged as a potentially effective therapeutic strategy for cancers such as pancreatic cancer, which are driven by genetic alterations that are not tractable drug targets. Although somatic mitochondrial genome (mtDNA) mutations have been observed in various tumors types, understanding of metabolic genotype-phenotype relationships is limited.MethodsWe deployed an integrated approach combining genomics, metabolomics, and phenotypic analysis on a unique cohort of patient-derived pancreatic cancer cell lines (PDCLs). Genome analysis was performed via targeted sequencing of the mitochondrial genome (mtDNA) and nuclear genes encoding mitochondrial components and metabolic genes. Phenotypic characterization of PDCLs included measurement of cellular oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) using a Seahorse XF extracellular flux analyser, targeted metabolomics and pathway profiling, and radiolabelled glutamine tracing.ResultsWe identified 24 somatic mutations in the mtDNA of 12 patient-derived pancreatic cancer cell lines (PDCLs). A further 18 mutations were identified in a targeted study of ~1000 nuclear genes important for mitochondrial function and metabolism. Comparison with reference datasets indicated a strong selection bias for non-synonymous mutants with predicted functional effects. Phenotypic analysis showed metabolic changes consistent with mitochondrial dysfunction, including reduced oxygen consumption and increased glycolysis. Metabolomics and radiolabeled substrate tracing indicated the initiation of reductive glutamine metabolism and lipid synthesis in tumours.ConclusionsThe heterogeneous genomic landscape of pancreatic tumours may converge on a common metabolic phenotype, with individual tumours adapting to increased anabolic demands via different genetic mechanisms. Targeting resulting metabolic phenotypes may be a productive therapeutic strategy.

Revised timeline and distribution of the earliest diverged human maternal lineages in southern Africa

The oldest extant human maternal lineages include mitochondrial haplogroups L0d and L0k found in the southern African click-speaking forager peoples broadly classified as Khoesan. Profiling these early mitochondrial lineages allows for better understanding of modern human evolution. In this study, we profile 77 new early-diverged complete mitochondrial genomes and sub-classify another 105 L0d/L0k individuals from southern Africa. We use this data to refine basal phylogenetic divergence, coalescence times and Khoesan prehistory. Our results confirm L0d as the earliest diverged lineage (∼172 kya, 95%CI: 149–199 kya), followed by L0k (∼159 kya, 95%CI: 136–183 kya) and a new lineage we name L0g (∼94 kya, 95%CI: 72–116 kya). We identify two new L0d1 subclades we name L0d1d and L0d1c4/L0d1e, and estimate L0d2 and L0d1 divergence at ∼93 kya (95%CI:76–112 kya). We concur the earliest emerging L0d1’2 sublineage L0d1b (∼49 kya, 95%CI:37–58 kya) is widely distributed across southern Africa. Concomitantly, we find the most recent sublineage L0d2a (∼17 kya, 95%CI:10–27 kya) to be equally common. While we agree that lineages L0d1c and L0k1a are restricted to contemporary inland Khoesan populations, our observed predominance of L0d2a and L0d1a in non-Khoesan populations suggests a once independent coastal Khoesan prehistory. The distribution of early-diverged human maternal lineages within contemporary southern Africans suggests a rich history of human existence prior to any archaeological evidence of migration into the region. For the first time, we provide a genetic-based evidence for significant modern human evolution in southern Africa at the time of the Last Glacial Maximum at between ∼21–17 kya, coinciding with the emergence of major lineages L0d1a, L0d2b, L0d2d and L0d2a.

Longitudinal study of user experiences of a CPOE system in a pediatric hospital

OBJECTIVE To explore the views of nurses and doctors during the early stages of implementation of a computerized provider order entry (CPOE) system in a pediatric hospital and to examine changes in perceptions and reported behaviors as use of the CPOE system became routine. METHODS Semi-structured interviews were undertaken at four time points following CPOE implementation: during week one, week three, week six and then six months following implementation. In total, 122 users were interviewed. Interviews were audio-recorded and transcribed verbatim. Emergent themes were mapped to the Extended Technology Acceptance Model (e-TAM). RESULTS Initial perceptions were driven by unfamiliarity with the system. As users became more proficient and efficient in using the CPOE system, additional safety benefits become apparent. However, accompanying increased reports of benefits were reports of usability problems and new types of errors arising from CPOE use. Reports of workarounds appeared for the first time at 6-month interviews. These workarounds were adopted to allow routine work to continue and to attenuate some of the perceived negative consequences of CPOE, including delayed medications and reduced patient interaction. CONCLUSION This study is one of the first to examine changes in perceptions of CPOE at multiple points, demonstrating the trajectory of changes in views over time. It provides new information about the time point at which workarounds begin to be embedded in practice and are potentially most receptive to identification and remediation. It suggests an adaptive implementation and support program would be beneficial, as reported difficulties and concerns change during the first six months of use.