Topoisomerase 1 Inhibition in MYC-Driven Cancer Promotes Aberrant R-Loop Accumulation to Induce Synthetic Lethality

CRISPR screening reveals topoisomerase 1 as an immediately actionable vulnerability in cancers harboring MYC as a driver oncoprotein that can be targeted with clinically approved inhibitors. MYC is a central regulator of gene transcription and is frequently dysregulated in human cancers. As targeting MYC directly is challenging, an alternative strategy is to identify specific proteins or processes required for MYC to function as a potent cancer driver that can be targeted to result in synthetic lethality. To identify potential targets in MYC-driven cancers, we performed a genome-wide CRISPR knockout screen using an isogenic pair of breast cancer cell lines in which MYC dysregulation is the switch from benign to transformed tumor growth. Proteins that regulate R-loops were identified as a potential class of synthetic lethal targets. Dysregulated MYC elevated global transcription and coincident R-loop accumulation. Topoisomerase 1 (TOP1), a regulator of R-loops by DNA topology, was validated to be a vulnerability in cells with high MYC activity. Genetic knockdown of TOP1 in MYC-transformed cells resulted in reduced colony formation compared with control cells, demonstrating synthetic lethality. Overexpression of RNaseH1, a riboendonuclease that specifically degrades R-loops, rescued the reduction in clonogenicity induced by TOP1 deficiency, demonstrating that this vulnerability is driven by aberrant R-loop accumulation. Genetic and pharmacologic TOP1 inhibition selectively reduced the fitness of MYC-transformed tumors in vivo. Finally, drug response to TOP1 inhibitors (i.e., topotecan) significantly correlated with MYC levels and activity across panels of breast cancer cell lines and patient-derived organoids. Together, these results highlight TOP1 as a promising target for MYC-driven cancers.Significance: CRISPR screening reveals topoisomerase 1 as an immediately actionable vulnerability in cancers harboring MYC as a driver oncoprotein that can be targeted with clinically approved inhibitors

Panton-Valentine Leukocidin Is Not the Primary Determinant of Outcome for Staphylococcus aureus Skin Infections: Evaluation from the CANVAS Studies

The impact of Panton-Valentine leukocidin (PVL) on the severity of complicated skin and skin structure infections (cSSSI) caused by Staphylococcus aureus is controversial. We evaluated potential associations between clinical outcome and PVL presence in both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) isolates from patients enrolled in two large, multinational phase three clinical trials assessing ceftaroline fosamil for the treatment of cSSSI (the CANVAS 1 and 2 programs). Isolates from all microbiologically evaluable patients with monomicrobial MRSA or MSSA infections (n = 473) were genotyped by PCR for pvl and underwent pulsed-field gel electrophoresis (PFGE). Genes encoding pvl were present in 266/473 (56.2%) isolates. Infections caused by pvl-positive S. aureus were associated with younger patient age, North American acquisition, and presence of major abscesses (P<0.001 for each). Cure rates of patients infected with pvl-positive and pvl-negative S. aureus were similar overall (93.6% versus 92.8%; P = 0.72), and within MRSA-infected (94.5% vs. 93.1%; P = 0.67) and MSSA-infected patients (92.2% vs. 92.7%; P = 1.00). This finding persisted after adjustment for multiple patient characteristics. Outcomes were also similar when USA300 PVL+ and non-USA300 PVL+ infections were compared. The results of this contemporary, international study suggest that pvl presence was not the primary determinant of outcome in patients with cSSSI due to either MRSA or MSSA

Deep learning-based polygenic risk analysis for Alzheimer's disease prediction

BACKGROUND: The polygenic nature of Alzheimer's disease (AD) suggests that multiple variants jointly contribute to disease susceptibility. As an individual's genetic variants are constant throughout life, evaluating the combined effects of multiple disease-associated genetic risks enables reliable AD risk prediction. Because of the complexity of genomic data, current statistical analyses cannot comprehensively capture the polygenic risk of AD, resulting in unsatisfactory disease risk prediction. However, deep learning methods, which capture nonlinearity within high-dimensional genomic data, may enable more accurate disease risk prediction and improve our understanding of AD etiology. Accordingly, we developed deep learning neural network models for modeling AD polygenic risk. METHODS: We constructed neural network models to model AD polygenic risk and compared them with the widely used weighted polygenic risk score and lasso models. We conducted robust linear regression analysis to investigate the relationship between the AD polygenic risk derived from deep learning methods and AD endophenotypes (i.e., plasma biomarkers and individual cognitive performance). We stratified individuals by applying unsupervised clustering to the outputs from the hidden layers of the neural network model. RESULTS: The deep learning models outperform other statistical models for modeling AD risk. Moreover, the polygenic risk derived from the deep learning models enables the identification of disease-associated biological pathways and the stratification of individuals according to distinct pathological mechanisms. CONCLUSION: Our results suggest that deep learning methods are effective for modeling the genetic risks of AD and other diseases, classifying disease risks, and uncovering disease mechanisms

An IL1RL1 genetic variant lowers soluble ST2 levels and the risk effects of APOE-ε4 in female patients with Alzheimer’s disease

Changes in the levels of circulating proteins are associated with Alzheimer’s disease (AD), whereas their pathogenic roles in AD are unclear. Here, we identified soluble ST2 (sST2), a decoy receptor of interleukin-33–ST2 signaling, as a new disease-causing factor in AD. Increased circulating sST2 level is associated with more severe pathological changes in female individuals with AD. Genome-wide association analysis and CRISPR–Cas9 genome editing identified rs1921622, a genetic variant in an enhancer element of IL1RL1, which downregulates gene and protein levels of sST2. Mendelian randomization analysis using genetic variants, including rs1921622, demonstrated that decreased sST2 levels lower AD risk and related endophenotypes in females carrying the Apolipoprotein E (APOE)-ε4 genotype; the association is stronger in Chinese than in European-descent populations. Human and mouse transcriptome and immunohistochemical studies showed that rs1921622/sST2 regulates amyloid-beta (Aβ) pathology through the modulation of microglial activation and Aβ clearance. These findings demonstrate how sST2 level is modulated by a genetic variation and plays a disease-causing role in females with AD

Chromosomal-level assembly of the Asian Seabass genome using long sequence reads and multi-layered scaffolding

We report here the ~670 Mb genome assembly of the Asian seabass (Lates calcarifer), a tropical marine teleost. We used long-read sequencing augmented by transcriptomics, optical and genetic mapping along with shared synteny from closely related fish species to derive a chromosome-level assembly with a contig N50 size over 1 Mb and scaffold N50 size over 25 Mb that span ~90% of the genome. The population structure of L. calcarifer species complex was analyzed by re-sequencing 61 individuals representing various regions across the species' native range. SNP analyses identified high levels of genetic diversity and confirmed earlier indications of a population stratification comprising three clades with signs of admixture apparent in the South-East Asian population. The quality of the Asian seabass genome assembly far exceeds that of any other fish species, and will serve as a new standard for fish genomics

Ybp2 Associates with the Central Kinetochore of Saccharomyces cerevisiae and Mediates Proper Mitotic Progression

The spindle checkpoint ensures the accurate segregation of chromosomes by monitoring the status of kinetochore attachment to microtubules. Simultaneous mutations in one of several kinetochore and cohesion genes and a spindle checkpoint gene cause a synthetic-lethal or synthetic-sick phenotype. A synthetic genetic array (SGA) analysis using a mad2Δ query mutant strain of yeast identified YBP2, a gene whose product shares sequence similarity with the product of YBP1, which is required for H2O2-induced oxidation of the transcription factor Yap1. ybp2Δ was sensitive to benomyl and accumulated at the mitotic stage of the cell cycle. Ybp2 physically associates with proteins of the COMA complex (Ctf19, Okp1, Mcm21, and Ame1) and 3 components of the Ndc80 complex (Ndc80, Nuf2, and Spc25 but not Spc24) in the central kinetochore and with Cse4 (the centromeric histone and CENP-A homolog). Chromatin-immunoprecipitation analyses revealed that Ybp2 associates specifically with CEN DNA. Furthermore, ybp2Δ showed synthetic-sick interactions with mutants of the genes that encode the COMA complex components. Ybp2 seems to be part of a macromolecular kinetochore complex and appears to contribute to the proper associations among the central kinetochore subcomplexes and the kinetochore-specific nucleosome

Genomic Sequencing and Comparative Analysis of Epstein-Barr Virus Genome Isolated from Primary Nasopharyngeal Carcinoma Biopsy

Whether certain Epstein-Barr virus (EBV) strains are associated with pathogenesis of nasopharyngeal carcinoma (NPC) is still an unresolved question. In the present study, EBV genome contained in a primary NPC tumor biopsy was amplified by Polymerase Chain Reaction (PCR), and sequenced using next-generation (Illumina) and conventional dideoxy-DNA sequencing. The EBV genome, designated HKNPC1 (Genbank accession number JQ009376) is a type 1 EBV of approximately 171.5 kb. The virus appears to be a uniform strain in line with accepted monoclonal nature of EBV in NPC but is heterogeneous at 172 nucleotide positions. Phylogenetic analysis with the four published EBV strains, B95-8, AG876, GD1, and GD2, indicated HKNPC1 was more closely related to the Chinese NPC patient-derived strains, GD1 and GD2. HKNPC1 contains 1,589 single nucleotide variations (SNVs) and 132 insertions or deletions (indels) in comparison to the reference EBV sequence (accession number NC007605). When compared to AG876, a strain derived from Ghanaian Burkitt's lymphoma, we found 322 SNVs, of which 76 were non-synonymous SNVs and were shared amongst the Chinese GD1, GD2 and HKNPC1 isolates. We observed 88 non-synonymous SNVs shared only by HKNPC1 and GD2, the only other NPC tumor-derived strain reported thus far. Non-synonymous SNVs were mainly found in the latent, tegument and glycoprotein genes. The same point mutations were found in glycoprotein (BLLF1 and BALF4) genes of GD1, GD2 and HKNPC1 strains and might affect cell type specific binding. Variations in LMP1 and EBNA3B epitopes and mutations in Cp (11404 C>T) and Qp (50134 G>C) found in GD1, GD2 and HKNPC1 could potentially affect CD8+ T cell recognition and latent gene expression pattern in NPC, respectively. In conclusion, we showed that whole genome sequencing of EBV in NPC may facilitate discovery of previously unknown variations of pathogenic significance

Decreased aortic growth and middle aortic syndrome in patients with neuroblastoma after radiation therapy

Background: Long-term CT follow-up studies are required in pediatric patients who have received intraoperative radiation therapy (IORT) and external beam radiation therapy (EBRT) to assess vascular toxicities and to determine the exact complication rate. Objective: To analyze with CT the effects of radiation therapy (RT) on the growth of the aorta in neuroblastoma patients.Materials and methods Abdominal CT scans of 31 patients with intraabdominal neuroblastoma (stage II–IV), treated with RT (20 IORT±EBRT, 11 EBRT alone), were analyzed retrospectively. The diameter of the abdominal aorta was measured before and after RT. These data were compared to normal and predicted normal aortic diameters of children, according to the model of Fitzgerald, Donaldson and Poznanski (aortic diameter in centimeters = 0.844 + 0.0599 × age in years), and to the diameters of a control group of children who had not undergone RT. Statistical analyses for the primary aims were performed using the chi-squared test, t-test, Mann-Whitney test, nonparametric Wilcoxon matched-pairs test and analysis of variance for repeated measures. Clinical files and imaging studies were evaluated for signs of late vascular complications of neuroblastoma patients who had received RT. Results: The mean diameter before and after RT and the growth of the aorta were significantly lower than expected in patients with neuroblastoma (P<0.05 for each) and when compared to the growth in a control group with normal and nonirradiated aortas. Among the patients who had received RT, there was no difference due to the type of RT. Seven patients from the IORT±EBRT group developed vascular complications, which included hypertension (five), middle aortic syndrome (two), death due to mesenteric ischemia (one) and critical aortic stenosis, which required aortic bypass surgery (two).Conclusion Patients with neuroblastoma who had received RT showed impaired growth of the abdominal aorta. Significant long-term vascular complications occurred in seven patients who received IORT±EBRT. Thus, CT evaluation of patients with neuroblastoma who receive RT should include not only reports of changes in tumor extension, but also documentation of perfusion, and the size and growth of the aorta and its branches over time

Demographic and Clinical Features and Prescribing Patterns of Psychotropic Medications in Patients with the Melancholic Subtype of Major Depressive Disorder in China

BACKGROUND: Little has been known about the demographic and clinical features of the melancholic subtype of major depressive disorder (MDD) in Chinese patients. This study examined the frequency of melancholia in Chinese MDD patients and explored its demographic and clinical correlates and prescribing patterns of psychotropic drugs. METHODS: A consecutively collected sample of 1,178 patients with MDD were examined in 13 psychiatric hospitals or psychiatric units of general hospitals in China nationwide. The cross-sectional data of patients' demographic and clinical characteristics and prescriptions of psychotropic drugs were recorded using a standardized protocol and data collection procedure. The diagnosis of the melancholic subtype was established using the Mini International Neuropsychiatric Interview (MINI). Medications ascertained included antidepressants, mood stabilizers, antipsychotics and benzodiazepines. RESULTS: Six hundred and twenty nine (53.4%) of the 1,178 patients fulfilled criteria for melancholia. In multiple logistic regression analyses, compared to non-melancholic counterparts, melancholic MDD patients were more likely to be male and receive benzodiazepines, had more frequent suicide ideations and attempts and seasonal depressive episodes, while they were less likely to be employed and receive antidepressants and had less family history of psychiatric disorders and lifetime depressive episodes. CONCLUSIONS: The demographic and clinical features of melancholic MDD in Chinese patients were not entirely consistent with those found in Western populations. Compared to non-melancholic MDD patients, melancholic patients presented with different demographic and clinical features, which have implications for treatment decisions

Complete Sequencing of pNDM-HK Encoding NDM-1 Carbapenemase from a Multidrug-Resistant Escherichia coli Strain Isolated in Hong Kong

BACKGROUND: The emergence of plasmid-mediated carbapenemases, such as NDM-1 in Enterobacteriaceae is a major public health issue. Since they mediate resistance to virtually all β-lactam antibiotics and there is often co-resistance to other antibiotic classes, the therapeutic options for infections caused by these organisms are very limited. METHODOLOGY: We characterized the first NDM-1 producing E. coli isolate recovered in Hong Kong. The plasmid encoding the metallo-β-lactamase gene was sequenced. PRINCIPAL FINDINGS: The plasmid, pNDM-HK readily transferred to E. coli J53 at high frequencies. It belongs to the broad host range IncL/M incompatibility group and is 88803 bp in size. Sequence alignment showed that pNDM-HK has a 55 kb backbone which shared 97% homology with pEL60 originating from the plant pathogen, Erwina amylovora in Lebanon and a 28.9 kb variable region. The plasmid backbone includes the mucAB genes mediating ultraviolet light resistance. The 28.9 kb region has a composite transposon-like structure which includes intact or truncated genes associated with resistance to β-lactams (bla(TEM-1), bla(NDM-1), Δbla(DHA-1)), aminoglycosides (aacC2, armA), sulphonamides (sul1) and macrolides (mel, mph2). It also harbors the following mobile elements: IS26, ISCR1, tnpU, tnpAcp2, tnpD, ΔtnpATn1 and insL. Certain blocks within the 28.9 kb variable region had homology with the corresponding sequences in the widely disseminated plasmids, pCTX-M3, pMUR050 and pKP048 originating from bacteria in Poland in 1996, in Spain in 2002 and in China in 2006, respectively. SIGNIFICANCE: The genetic support of NDM-1 gene suggests that it has evolved through complex pathways. The association with broad host range plasmid and multiple mobile genetic elements explain its observed horizontal mobility in multiple bacterial taxa