Abstract
Background
Overcoming oxidative stress is a critical step for tumor progression; however, the underlying mechanisms in colorectal cancer (CRC) remain unclear.
Methods
We investigated ...nicotinamide adenine dinucleotide (phosphate) (NAD(P))-dependent enzyme methylene tetrahydrofolate dehydrogenase 2 (MTHFD2) expression, clinical relevance, redox modification, and molecular mechanisms using the CRC cells and tissues (n = 462 paired samples). The antitumor effects of MTHFD2 inhibitor LY345899 on CRC tumorigenesis and metastasis were evaluated in vitro and in vivo. Data analysis used Kaplan-Meier, Pearson’s correlation, and Student t test where appropriate. All statistical tests were two-sided.
Results
Here, we report that the patients with high expression of MTHFD2 have a shorter overall survival (HR = 1.62, 95% CI = 1.12 to 2.36, P = .01) and disease-free survival (HR = 1.55, 95% CI = 1.07 to 2.27, P = .02) than patients with low MTHFD2 expression. Suppression of MTHFD2 disturbs NADPH and redox homeostasis and accelerates cell death under oxidative stress, such as hypoxia or anchorage independence (P ≤ .01 for all). Also, genetic or pharmacological inhibition of MTHFD2 suppresses CRC cell growth and lung and peritoneal metastasis in cell-based xenografts (n = 5–8 mice per group). Importantly, LY345899 treatment statistically significantly suppresses tumor growth and decreases the tumor weight in CRC patient-derived xenograft models (n = 10 mice per group, mean SD tumor weight of the vehicle-treated group was 1.83 0.19 mg vs 0.74 0.30 mg for the LY345899-treated group, P < .001)
Conclusions
Our study presents evidence that MTHFD2 confers redox homeostasis and promotes CRC cell growth and metastasis. The folate analog LY345899 as MTHFD2 inhibitor displays therapeutic activity against CRC and warrants further clinical investigation for CRC treatment.
Objective
To assess polymorphism in Kelch 13 gene of Plasmodium falciparum isolates in Lagos, Nigeria.
Methods
195 Plasmodium falciparum‐positive dried blood spots collected from individuals that ...accessed diagnostic care at some health facilities and during community surveys across several Local Government Areas of Lagos State, Nigeria, were investigated for the presence of mutations in the K13 gene by nested polymerase chain reaction (PCR) using haplotype‐specific probes and sequencing.
Results
Three mutant genotypes of K13 gene were observed: A578S in 0.5%, D464N in 0.5% and Q613H in 1.5%. The frequency of K13 polymorphism was 3.1%, while the remaining parasite population had the wild K13 propeller genes.
Conclusion
No validated Kelch 13 polymorphism associated with artemisinin resistance was seen among P. falciparum isolates from Lagos, Nigeria. As no clinical study was done, this could not be correlated with artemisinin sensitivity.
Objectif
Evaluer le polymorphisme du gène Kelch 13 dans les isolats de Plasmodium falciparum à Lagos, au Nigéria.
Méthodes
195 gouttes de sang séchées positives pour Plasmodium falciparum recueillies auprès d'individus ayant accédé à des soins de diagnostic dans certains centres de santé et lors d'enquêtes communautaires menées dans plusieurs zones du gouvernement local de l'Etat de Lagos, au Nigéria, ont été examinées pour rechercher la présence de mutations du gène K13 par la réaction en chaîne imbriquée de la polymérase (PCR) en utilisant des sondes spécifiques à l'haplotype et par le séquençage.
Résultats
Trois génotypes mutants du gène K13 ont été observés: A578S dans 0,5%, D464N dans 0,5% et Q613H dans 1,5%. La fréquence du polymorphisme K13 était de 3,1%, alors que la population parasitaire restante avait les gènes sauvages de l'hélice K13.
Conclusion
Aucun polymorphisme validé de Kelch 13 associé à une résistance à l'artémisinine n'a été observé parmi les isolats de P. falciparum de Lagos, au Nigéria. Aucune étude clinique n'ayant été réalisée, il n'a pas été possible d’établir une corrélation entre cette observation et la sensibilité à l'artémisinine.
Given the wide presence of heterogeneous natural organic matter (NOM) and metal ions (Na+/Ca2+/Mg2+), as well as their significant role in governing nanoparticle stability in aqueous environments, it ...is of great importance to understand how the molecular weight (MW)-dependent physicochemical properties of NOM impact fundamental transportation processes like the aggregation of engineered nanoparticles (ENPs) in the presence of Na+/Ca2+/Mg2+. Here, we report on the aggregation behavior of a model ENP, fullerene nanoparticles (nC60) in the presence of five MW fractions of Suwannee River NOM (Mf-SRNOMs, separated by ultrafiltration techniques) and three electrolytes (NaCl, CaCl2 and MgCl2). We found that in all NaCl treatments and low concentration CaCl2/MgCl2 treatments, the enhancement of nC60 stability positively correlated with the MW of Mf-SRNOMs. Whereas, the stability efficiency of identical Mf-SRNOM in different electrolytes followed an order of NaCl > MgCl2 > CaCl2, and the enhanced attachment of nC60-SRNOM associations was observed in high MW Mf-SRNOM (SRNOM>100 kD and SRNOM 30–100 kD) at high concentration CaCl2/MgCl2. Our results indicate that although the high MW NOM with large humic-like material is the key component for stabilizing nC60 in monovalent electrolyte, it could play a reversed role in promoting the attachment of nC60, especially in long term aggregations and at high concentrations of divalent cations. Therefore, a detailed understanding of the effects of heterogeneous NOM on the aggregation of ENPs should be highly valued, and properly assessed against different cation species and concentrations.
Display omitted
•Enhancement of nC60 stability positively correlates with the MW of NOM in NaCl.•nC60 stability in NOM is electrolyte dependent and follows NaCl > MgCl2> CaCl2.•High MW NOMs stabilize nC60 in NaCl more effectively than low MW counterparts.•High MW NOMs promote nC60 attachment and thus aggregation in divalent cations.
Currently in China, the trend of Plasmodium vivax cases imported from Southeast Asia was increased especially in the China-Myanmar border area. Driven by the increase in P. vivax cases and stronger ...need for vaccine and drug development, several P. vivax isolates genome sequencing projects are underway. However, little is known about the genetic variability in this area until now.
The sequencing of the first P. vivax isolate from China-Myanmar border area (CMB-1) generated 120 million paired-end reads. A percentage of 10.6 of the quality-evaluated reads were aligned onto 99.9% of the reference strain Sal I genome in 62-fold coverage with an average of 4.8 SNPs per kb. We present a 539-SNP marker data set for P. vivax that can identify different parasites from different geographic origins with high sensitivity. We also identified exceptionally high levels of genetic variability in members of multigene families such as RBP, SERA, vir, MSP3 and AP2. The de-novo assembly yielded a database composed of 8,409 contigs with N50 lengths of 6.6 kb and revealed 661 novel predicted genes including 78 vir genes, suggesting a greater functional variation in P. vivax from this area.
Our result contributes to a better understanding of P. vivax genetic variation, and provides a fundamental basis for the geographic differentiation of vivax malaria from China-Myanmar border area using a direct sequencing approach without leukocyte depletion. This novel sequencing method can be used as an essential tool for the genomic research of P. vivax in the near future.
The fast growing and abundant use of silver nanoparticles (AgNPs) in commercial products alerts us to be cautious of their unknown health and environmental risks. Because of the inherent redox ...instability of silver, AgNPs are highly dynamic in the aquatic system, and the cycle of chemical oxidation of AgNPs to release Ag(+) and reconstitution to form AgNPs is expected to occur in aquatic environments. This study investigated how inevitable environmentally relevant factors like sunlight, dissolved organic matter (DOM), pH, Ca(2+)/Mg(2+), Cl(-), and S(2-) individually or in combination affect the chemical transformation of AgNPs. It was demonstrated that simulated sunlight induced the aggregation of AgNPs, causing particle fusion or self-assembly to form larger structures and aggregates. Meanwhile, AgNPs were significantly stabilized by DOM, indicating that AgNPs may exist as single particles and be suspended in natural water for a long time or delivered far distances. Dissolution (ion release) kinetics of AgNPs in sunlit DOM-rich water showed that dissolved Ag concentration increased gradually first and then suddenly decreased with external light irradiation, along with the regeneration of new tiny AgNPs. pH variation and addition of Ca(2+) and Mg(2+) within environmental levels did not affect the tendency, showing that this phenomenon was general in real aquatic systems. Given that a great number of studies have proven the toxicity of dissolved Ag (commonly regarded as the source of AgNP toxicity) to many aquatic organisms, our finding that the effect of DOM and sunlight on AgNP dissolution can regulate AgNP toxicity under these conditions is important. The fact that the release of Ag(+) and regeneration of AgNPs could both happen in sunlit DOM-rich water implies that previous results of toxicity studies gained by focusing on the original nature of AgNPs should be reconsidered and highlights the necessity to monitor the fate and toxicity of AgNPs under more environmentally relevant conditions.
Malaria is a public health concern worldwide, and Togo has proven to be no exception. Effective approaches to provide information on biological insights for disease elimination are therefore a ...research priority. Local selection on malaria pathogens is due to multiple factors including host immunity. We undertook genome-wide analysis of sequence variation on a sample of 10
(Pf) clinical isolates from Togo to identify local-specific signals of selection. Paired-end short-read sequences were mapped and aligned onto > 95% of the 3D7 Pf reference genome sequence in high fold coverage. Data on 266 963 single nucleotide polymorphisms were obtained, with average nucleotide diversity π = 1.79 × 10
. Both principal component and neighbor-joining tree analyses showed that the Togo parasites clustered according to their geographic (Africa) origin. In addition, the average genome-wide diversity of Pf from Togo was much higher than that from other African samples. Tajima's
value of the Togo isolates was -0.56, suggesting evidence of directional selection and/or recent population expansion. Against this background, within-population analyses identifying loci of balancing and recent positive selections evidenced that host immunity has been the major selective agent. Importantly, 87 and 296 parasite antigen genes with Tajima's
values > 1 and in the top 1% haplotype scores, respectively, include a significant representation of membrane proteins at the merozoite stage that invaded red blood cells (RBCs) and parasitized RBCs surface proteins that play roles in immunoevasion, adhesion, or rosetting. This is consistent with expectations that elevated signals of selection due to allele-specific acquired immunity are likely to operate on antigenic targets. Collectively, our data suggest a recent expansion of Pf population in Togo and evidence strong host immune selection on membrane/surface antigens reflected in signals of balancing/positive selection of important gene loci. Findings from this study provide a fundamental basis to engage studies for effective malaria control in Togo.
In malaria-free countries, imported cases are challenging because interconnections with neighboring countries with higher transmission rates increase the risk of parasite reintroduction. Establishing ...a genetic database for rapidly identifying malaria importation or reintroduction is crucial in addressing these challenges. This study aimed to examine genomic epidemiology during the pre-elimination stage by retrospectively reporting whole-genome sequence variation of 10
isolates from inland China.
The samples were collected during the last few inland outbreaks from 2011 to 2012 when China implemented a malaria control plan. After next-generation sequencing, we completed a genetic analysis of the population, explored the geographic specificity of the samples, and examined clustering of selection pressures. We also scanned genes for signals of positive selection.
China's inland populations were highly structured compared to the surrounding area, with a single potential ancestor. Additionally, we identified genes under selection and evaluated the selection pressure on drug-resistance genes. In the inland population, positive selection was detected in some critical gene families, including
, and
. Meanwhile, we identified selection signatures in drug resistance, such as
, and
, and noticed that the ratio of wild-type
and
increased after China banned sulfadoxine-pyrimethamine (SP) for decades.
Our data provides an opportunity to investigate the molecular epidemiology of pre-elimination inland malaria populations, which exhibited lower selection pressure on invasion and immune evasion genes than neighbouring areas, but increased drug resistance in low transmission settings. Our results revealed that the inland population was severely fragmented with low relatedness among infections, despite a higher incidence of multiclonal infections, suggesting that superinfection or co-transmission events are rare in low-endemic circumstances. We identified selective signatures of resistance and found that the proportion of susceptible isolates fluctuated in response to the prohibition of specific drugs. This finding is consistent with the alterations in medication strategies during the malaria elimination campaign in inland China. Such findings could provide a genetic basis for future population studies, assessing changes in other pre-elimination countries.
Malaria incidence has declined dramatically over the past decade and China was certified malaria-free in 2021. However, the presence of malaria in border areas and the importation of cases of malaria ...parasites are major challenges for the consolidation of the achievements made by China.
Duffy binding protein (PvDBP) performs a significant role in erythrocyte invasion, and is considered a promising
vaccine. However, the highly polymorphic region of PvDBP (PvDBP-II) impedes the development of blood-stage vaccine against
. In this study, we investigated the genetic diversity and natural selection of PvDBP-II among 124
isolates collected from the China-Myanmar border (CMB) in Yunnan Province, China, during 2009-2011. To compare genetic diversity, natural selection, and population structure with CMB isolates, 85
II sequences of eastern Myanmar isolates were obtained from GenBank. In addition, global sequences of
-II were retrieved from GenBank to establish genetic differentiation relationships and networks with the CMB isolates. In total, 22 single nucleotide polymorphisms reflected in 20 non-synonymous and two synonymous mutations were identified. The overall nucleotide diversity of PvDBP-II from the 124 CMB isolates was 0.0059 with 21 haplotypes identified (
= 0.91). The high ratio of non-synonymous to synonymous mutations suggests that PvDBP-II had evolved under positive selection. Population structure analysis of the CMB and eastern Myanmar isolates were optimally grouped into five sub-populations (
= 5). Polymorphisms of PvDBP-II display that CMB isolates were genetically diverse. Mutation, recombination, and positive selection promote polymorphism of PvDBP-II of
population. Although low-level genetic differentiation in eastern Myanmar was identified along with the more effective malaria control measures, the complexity of population structure in malaria parasites has maintained. In conclusion, findings from this study advance knowledge of the understanding of the dynamic of
population, which will contribute to guiding the rational design of a PvDBP-II based vaccine.
To reveal the genetic characteristics of one member of the Plasmodium falciparum repetitive interspersed family (rif), we sequenced the rif gene (PF3D7_1254800) in 53 field isolates collected from ...Ghana-imported cases into China and compared them with 350 publicly available P. falciparum rif sequences from global populations. In the Ghana-imported population, the nucleotide diversities were 0.05714 and 0.06616 for the full length and variable region of rif gene, respectively. Meanwhile, 22 and 20 haplotypes were identified for the full length and variable region of rif gene (Hd = 0.843 and 0.838, respectively). Diversity of rif gene in Ghana-imported population was higher than that observed in Cambodia, Thailand, Vietnam, Myanmar, Mali, Ghana, and Senegal populations. In this analysis, we found high genetic diversity of rif gene in global P. falciparum populations and identified 158 haplotypes. Tajima's D-test shows that there are large differences in the direction of selection between the conserved and variable region of rif gene. Tajima's D value for the variable region was 0.20074, indicating that balancing selection existed in this region. We found that the variable region was the main target of selection for positive diversification, and most mutation sites were located in this region. The population structure suggested optimized cluster values of K = 6. The five groups in Ghana-imported population included a unique subpopulation. Our results reveal the dynamics of the rif gene (PF3D7_1254800) in P. falciparum populations, which can aid in the rational design of P. falciparum rif-based vaccines.
•Genetic polymorphism of the rif gene (PF3D7_1254800) was analyzed from global P. falciparum isolates.•Nucleotide diversity of rif gene from the 53 Ghana imported isolates was 0.05714.•Variable region of rif gene is dominant target of positive selection for Ghana imported isolates.
Background Plasmodium falciparum-resistance to sulphadoxine-pyrimethamine (SP) has been largely reported among pregnant women. However, the profile of resistance markers to SP dihydrofolate reductase ...(dhfr) and dihydropteroate synthase (dhps) in the general population are varied and not frequently monitored. Currently, SP is used as partner drug for artemisinin combination therapy (SP-artesunate) in some sub-Saharan African countries or as a prophylactic drug in intermittent preventive treatment of malaria during pregnancy and infants and in seasonal malaria chemoprevention (SMC). Profiling of P. falciparum-resistant genotypes to SP is dynamic and critical in providing data that would be useful for malaria control programmes. This study assessed the profile of dhfr and dhps genes genotypes among individuals with malaria in Lagos, Nigeria. Methods Molecular markers of SP resistance were identified by nested PCR and sequenced among malaria positive dried blood spots (DBS) that were collected from individuals attending health facilities from January 2013 to February 2014 and during community surveys from October 2010 to September 2011 across different Local Government Areas of Lagos State, Nigeria. Results A total of 242 and 167 samples were sequenced for dhfr and dhps, respectively. Sequence analysis of dhfr showed that 95.5% (231/242), 96.3% (233/242) and 96.7% (234/242) of the samples had N51I, C59R and S108N mutant alleles, respectively. The prevalence of dhps mutation at codons A437G, A613S, S436A, A581G, I431V and K540E were 95.8% (160/167), 41.9% (70/167), 41.3% (69/167), 31.1% (52/167), 25.1% (42/167), and 1.2% (2/167) respectively. The prevalence of triple mutations (CIRNI) in dhfr was 93.8% and 44.3% for the single dhps haplotype mutation (SGKAA). Partial SP-resistance due to quadruple dhfr-dhps haplotype mutations (CIRNI-SGKAA) and octuple haplotype mutations (CIRNI-VAGKGS) with rate of 42.6% and 22.0%, respectively has been reported. Conclusions There was increased prevalence in dhfr triple haplotype mutations when compared with previous reports in the same environment but aligned with high prevalence in other locations in Nigeria and other countries in Africa. Also, high prevalence of dhfr and dhps mutant alleles occurred in the study areas in Lagos, Nigeria five to eight years after the introduction of artemisinin combination therapy underscores the need for continuous monitoring. Keywords: Plasmodium falciparum, Antimalarial drug resistance, Sulphadoxine-pyrimethamine, Dihydrofolate reductase, Dihydropteroate synthase
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