[Prevalence of Echinococcus infections in small rodents in Yushu City, Qinghai Province in 2023]

OBJECTIVE

To investigate the prevalence of Echinococcus infections in small rodents around human residential areas in Yushu City, Qinghai Province in 2023, so as to provide insights into precision echinococcosis control.

METHODS

One or two quadrats, each measuring 50 m × 50 m, were randomly assigned in Shanglaxiu Township and Longbao Township, Yushu City, Qinghai Province on June 2023, respectively, and 300 plate-type mouse traps, each measuring 12.0 cm × 6.5 cm, were assigned in each quadrat. Small rodents were captured during the period between 10 : 00 and 18 : 00 each day for 4 days. Then, all captured small rodents were identified and dissected, and liver specimens with suspected Echinococcus infections were subjected to pathological examinations. The Echinococcus cytochrome c oxidase 1 (cox1) gene was amplified using PCR assay, and the sequence of the amplified product was aligned to that was recorded in the GenBank to characterize the parasite species. In addition, a phylogenetic tree of Echinococcus was generated based on the cox1 gene sequence using the neighbor-joining method.

RESULTS

A total of 236 small rodents were captured in Shanglaxiu and Longbao townships, Yushu City, including 65 Qinghai voles and 51 plateau pikas in Shanglaxiu Township, and 62 Qinghai voles and 58 plateau pikas in Longbao Township, and there was no significant difference in the constituent ratio of small rodents between the two townships (χ2 = 0.294, P > 0.05). Seven plateau pikas and 12 Qinghai voles were suspected to be infected with Echinococcus by dissection, and pathological examinations showed unclear structure of hepatic lobules and disordered hepatocyte arrangement in livers of small rodents suspected of Echinococcus infections. PCR assay identified E. shiquicus DNA in 7 Qinghai voles, which were all captured from Shanglaxiu Township. Phylogenetic analysis showed that the cox1 gene sequence of Echinococcus in small rodents was highly homologous to the E. shiquicus cox1 gene sequence reported previously.

CONCLUSIONS

Plateau pika and Qinghai vole were predominant small rodents around human residential areas in Yushu City, Qinghai Province in 2023, and E. shiquicus infection was detected in Qinghai voles.

Prediction of Alzheimer's Disease Based on 3D Genome Selected circRNA

Alzheimer's disease (AD) is a neurodegenerative disease and there is by far no effective treatment for it, especially in its late stage. Circular RNAs (circRNAs), known as a class of non-coding RNAs are widely observed in eukaryotic transcriptomes, and are reported to play an important role in neurodegenerative diseases including AD. circRNAs usually act as microRNA (miRNA) inhibitors or «sponges» to regulate the function of miRNAs, leading to subsequent changes in protein activities and functions. Accumulating evidence indicates that circRNAs can serve as potential biomarker in AD early prediction. The functional roles of circRNAs are very versatile including miRNAs binding - thus affecting downstream gene expression, generating abnormally translated protein peptides, and affecting epigenetic modifications which subsequently affect AD related gene expressions. Therefore, identifying AD-related circRNAs can contribute to AD early diagnosis and intervention. In this work, we collected and curated an AD-related circRNA dataset; by exploring the circRNAs' corresponding DNA loci distribution in chromatin 3D conformation (3D genome) and utilize the such 3D genome information, we were able to selected a concise yet predictively effective circRNA panel, based on which, significantly better AD prediction machine learning models were achieved.

Polarized tip-enhanced Raman spectroscopy at liquid He temperature in ultrahigh vacuum using an off-axis parabolic mirror

Tip-enhanced Raman spectroscopy (TERS) combines inelastic light scattering well below the diffraction limit down to the nanometer range and scanning probe microscopy and, possibly, spectroscopy. In this way, topographic and spectroscopic as well as single- and two-particle information may simultaneously be collected. While single molecules can now be studied successfully, bulk solids are still not meaningfully accessible. It is the purpose of the work presented here to outline approaches toward this objective. We describe a home-built, liquid helium cooled, ultrahigh vacuum TERS. The setup is based on a scanning tunneling microscope and, as an innovation, an off-axis parabolic mirror having a high numerical aperture of ∼0.85 and a large working distance. The system is equipped with a fast load-lock chamber, a chamber for the in situ preparation of tips, substrates, and samples, and a TERS chamber. Base pressure and temperature in the TERS chamber were ∼3 × 10-11 mbar and 15 K, respectively. Polarization dependent tip-enhanced Raman spectra of the vibration modes of carbon nanotubes were successfully acquired at cryogenic temperature. The new features described here including very low pressure and temperature and the external access to the light polarizations, thus the selection rules, may pave the way toward the investigation of bulk and surface materials.

Analysing neutron radiation damage in YBa2 Cu3 O7-x high temperature superconductor tapes

Superconducting windings will be necessary in future fusion reactors to generate the strong magnetic fields needed to confine the plasma, and these superconducting materials will inevitably be exposed to neutron damage. It is known that this exposure results in the creation of isolated damage cascades, but the presence of these defects alone is not sufficient to explain the degradation of macroscopic superconducting properties and a quantitative method is needed to assess the subtle lattice damage in between the clusters. We have studied REBCO coated conductors irradiated with neutrons to a cumulative dose of 3.3×10²²  n*m^-2  that show a degradation of both T_c  and J_c values, and use HRTEM analysis to show that this irradiation introduces ∼10 nm amorphous collision cascades. In addition we introduce a new method for the analysis of these images to quantify the degree of lattice disorder in the apparently perfect matrix between these cascades. This method utilises Fast Fourier and Discrete Cosine Transformations of a statistically-relevant number of HRTEM images of pristine, neutron-irradiated, and amorphous samples, and extracts the degree of randomness in terms of entropy values. Our results show that these entropy values in both mid-frequency band FFT and DCT domains correlate with the expected level of lattice damage, with the pristine samples having the lowest and the fully amorphous regions the highest entropy values.  Our methodology allows us to quantify 'invisible' lattice damage to and correlate these values to the degradation of superconducting properties, and also has relevance for a wider range of applications in the field of electron microscopy where small changes in lattice perfection need to be measured. This article is protected by copyright. All rights reserved.

Abstract P053: VAL-083 (dianhydrogalactitol) synergizes with PARP inhibitors in BRCA-proficient and BRCA-deficient ovarian cancer models

Platinum (Pt)-based chemotherapy plays a key role in ovarian cancer treatment, but patients frequently develop Pt-resistance. Dysfunctional p53 is implicated in Pt-resistance, comprising a therapeutic challenge in high grade serous ovarian carcinoma (HGSOC), where p53 is universally mutated. Attempts to overcome Pt-resistance in HGSOC include agents blocking the DNA repair pathways, most notably PARP inhibitors (PARPi), leading to accumulation of DNA double strand breaks (DSBs) and cancer cell death. Sensitivity to PARPi is correlated with deficiencies in the homologous recombination (HR) DNA repair system, which accurately repairs DSBs. BRCA1 and BRCA2 are key proteins in HR, and mutated BRCA1/2 are well-established biomarkers for PARPi sensitivity. PARPi treatment of Pt-sensitive ovarian cancers have improved progression free survival; however, improvements in overall survival have not been achieved and a 5-year survival rate of 40% remains in ovarian cancer. Additionally, resistance to PARPi has emerged as a significant clinical challenge. VAL-083 is a first-in-class bifunctional DNA damaging agent with demonstrated clinical activity against a range of cancers, including ovarian. VAL-083 rapidly induces interstrand cross-links at guanine-N7 leading to DSBs, activation of the HR repair pathway and cancer cell death. VAL-083 is able to overcome cisplatin-resistance in a panel of ovarian cancer in vitro models. We have also shown that VAL-083 maintains activity independent of prominent DNA repair mechanisms implicated in resistance to numerous chemotherapeutics including cisplatin and PARPi such as MGMT, non-homologous end-joining and mismatch repair. Cancer cells thus rely heavily on a functional HR pathway for repair of VAL-083-induced DSBs. This rationalizes VAL-083 combination therapy with agents inducing DSBs or blocking their repair, including PARPi. Taken together, these data highlight VAL-083's potential for targeting Pt-resistant HGSOC in combination with PARPi. METHODS: The cytotoxicity of VAL-083 in combination with PARPi (olaparib, niraparib, rucaparib, veliparib or talazoparib) against HR-impaired (BRCA siRNA knockdown) and HR-proficient (control siRNA) ovarian cancer cells was studied. RESULTS: We report increased VAL-083 cytotoxicity against HR-impaired A2780 cancer cells. In addition, synergy between VAL-083 and olaparib, talazoparib and niraparib in both HR-proficient and deficient settings. VAL-083 combination with rucaparib produced synergistic cytotoxicity in the HR-deficient setting, while VAL-083 combination with veliparib was additive. These data demonstrate that VAL-083 can synergize with some PARPi in both HR-proficient and HR-deficient settings. CONCLUSION: Our results demonstrate a distinct DNA-damaging mechanism for VAL-083, resulting in the ability to overcome cisplatin-resistance in HR-impaired tumors. In addition, VAL-083 synergized with several PARPi, particularly olaparib, rucaparib and talazoparib, in both HR-proficient and deficient ovarian tumor cells.

Citation Format: Anne Steino, Guangan He, Beibei Zhai, Jeffrey Bacha, Dennis M. Brown, Mads Daugaard, Zahid H. Siddik. VAL-083 (dianhydrogalactitol) synergizes with PARP inhibitors in BRCA-proficient and BRCA-deficient ovarian cancer models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P053.

Abstract 1073: Preclinical tissue biodistribution and plasma pharmacokinetic studies with oxaliTEX, a novel platinum(IV)-based oxaliplatin prodrug

Purpose: OxaliTEX is a texaphyrin-platinum(IV) prodrug with the ability to deliver the oxaliplatin payload to cisplatin-resistant tumor cells and restore wild-type p53 activation. As a result, the conjugate overcomes both multifactorial mechanisms of cisplatin resistance and transport-defective mechanism of oxaliplatin resistance. In an effort to prepare for translational studies, we have explored its distribution and pharmacokinetics (PK) in mice.

Experimental Procedures: Athymic male and/or female nude mice (3-4/group), with or without subcutaneously implanted (flank) HCT-116 colon xenograft, received oxaliplatin (4 mg/kg) and an equimolar (17 mg/kg) or a similar therapeutic (50 mg/kg) dose of oxaliTEX iv. After 24 hours, mice were exsanguinated under anesthesia and plasma and tissues isolated. A separate group of female mice received oxaliTEX (50 mg/kg) and blood was taken at multiple times over the next 24 hours, plasma isolated and samples denatured to prepare protein-free supernatant (PFS) representing “free” platinum. Samples were analyzed for platinum (Pt) by flameless atomic absorption spectrophotometry.

Results: At equimolar doses, gross sex differences in plasma or tissue concentrations were not observed for either drug. However, plasma Pt levels with oxaliTEX (0.6-0.7 ng Pt/ml) were 7-fold greater than with oxaliplatin (0.08-0.1 ng/ml). Similarly, a 3-fold greater concentration was also noted in liver (~1.4 vs. ~0.4 ng/mg) and heart (~0.5 vs. ~0.15 ng/mg) from mice treated with the prodrug. Tissues with ≤2-fold differences between the drugs in Pt levels were testes, kidney, ovary, lung, ileum and spleen, with undetectable levels in brain. In female mice bearing HCT-116 xenografts, the general tissue distribution pattern of each drug at the therapeutic dose was unchanged and demonstrated that increasing the oxaliTEX dose resulted in proportionate increase in tissue Pt levels. Notably, tumor Pt levels were ~5-fold greater with the conjugate (oxaliTEX, 1.1 ng Pt/mg; oxaliplatin, 0.21 ng/mg). PK analysis revealed that Pt in plasma and PFS was detectable for the entire 24 hr period and decayed in a biphasic manner, with respective α-phase half-life of 0.07 and 0.2 hr and β-phase half-life of 27 and 11 hr. The AUC in plasma and PFS was 172 and 3.7 μg.hr/ml, respectively.

Conclusions: Results suggest that oxaliTEX is sequestered in the plasma by protein binding, leaving low-level systemic exposure to “free” non-protein bound Pt. Since the tissue levels are greater than oxaliplatin at equimolar and/or therapeutic doses in specific organs, this suggests that the low level exposure to “free” Pt contributes to drug tolerance of normal tissues, whereas the tumor-targeting design feature contributes to greater tumor uptake that enhances antitumor effects. Funding was provided by Cancer Prevention and Research Institute of Texas

Citation Format: Guangan He, Gregory Thiabaud, Kathyrin A. Shelton, Luke J. Segura, Jonathan L. Sessler, Rick A. Finch, Zahid H. Siddik, Jonathan F. Arambula. Preclinical tissue biodistribution and plasma pharmacokinetic studies with oxaliTEX, a novel platinum(IV)-based oxaliplatin prodrug [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1073.

Histological analysis of spermatogenesis and the germ cell seasonal development within the testis of domesticated tree shrews (Tupaia belangeri chinensis)

This study aimed to address the lack of information on the male germ cell seasonal development of domesticated tree shrews (Tupaia belangeri chinensis). Testicular tissues were collected from 60 tree shrews (n=5 per month). The ultrastructures of the testes and spermatids were examined via transmission electron microscopy. Apoptosis of spermatogenic cells was measured through terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The expression of proliferation factors, namely, proliferating cell nuclear antigen (PCNA) and Ki67, in testicular tissues was assayed through immunohistochemistry. Spermatids ultrastructure showed seasonal differences, and spermatogenesis was relatively active in June and July and relatively stagnant from October to November. The percentage of TUNEL-positive germ cells was less during October and November, while greater in July than other phases. The number of PCNA-nucleus-positive germ cells was most in June and July, but with cytoplasm staining from October to November. Ki67 presented positive expression in the testes from April to September, with highest expression in June, but with no expression from October to March. In summary, there are seasonal differences in tissue morphology related to spermatogenesis in domesticated tree shrews. PCNA expression and Ki67 expression are good indicators of seasonal differences in male germ cells.

Remote Mesoscopic Signatures of Induced Magnetic Texture in Graphene

Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this Letter, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and remote phenomena in transport. Our experiments are performed in a graphene-based interaction-detection geometry, in which an artificial magnetic texture is induced in the graphene layer by covering a portion of it with a micromagnet. When probing conduction at some distance from this region, the strong influence of remote factors is manifested through the appearance of giant conductance fluctuations, with amplitude much larger than e^{2}/h. This violation of one of the fundamental tenets of mesoscopic physics dramatically demonstrates how local considerations can be overwhelmed by remote signatures in phase-coherent conductors.

Oncolytic HSV Therapy Modulates Vesicular Trafficking Inducing Cisplatin Sensitivity and Antitumor Immunity

PURPOSE

Here we investigated the impact of oncolytic herpes simplex virus (HSV) treatment on cisplatin sensitivity of platinum-resistant ovarian cancer, and the impact of the combination on immunotherapy.

EXPERIMENTAL DESIGN

Therapeutic efficacy of the combination was assessed in platinum-resistant human and murine ovarian cancer peritoneal metastatic mouse models (n = 9-10/group). RNA sequencing along with flow cytometry of splenocytes from treated mice was employed to examine the effect of antitumor immune response (n = 3/group). Anti-PD-1 antibody was performed to evaluate impact on checkpoint inhibition in vivo.

RESULTS

Gene Ontology pathway analysis uncovered disruption of cellular extracellular vesicle (EV)-related pathways in infected cells (FDR = 2.97E-57). Mechanistically, we identified reduced expression of transporters expressed on EV implicated in cisplatin efflux. The increased cisplatin retention led to increased cisplatin-DNA adducts, which resulted in micronuclei and the subsequent activation of cGAS-STING pathway with a significant activation of innate immune cells and translated to an increase in antitumor immunity and efficacy. In mice bearing platinum-resistant ovarian cancer, we also observed a feedback induction of PD-L1 on tumor cells, which sensitized combination-treated mice to anti-PD-1 immune checkpoint therapy.

CONCLUSIONS

To our knowledge, this is the first report to show HSV-induced cisplatin retention in infected cells. The consequential increased damaged DNA was then expelled from cells as micronuclei which resulted in induction of inflammatory responses and education of antitumor immunity. The combination therapy also created an environment that sensitized tumors to immune checkpoint therapy.

Raman Study of Cooper Pairing Instabilities in (Li_{1-x}Fe_{x})OHFeSe

We studied the electronic Raman spectra of (Li_{1-x}Fe_{x})OHFeSe as a function of light polarization and temperature. In the B_{1g} spectra alone we observe the redistribution of spectral weight expected for a superconductor and two well-resolved peaks below T_{c}. The nearly resolution-limited peak at 110  cm^{-1} (13.6 meV) is identified as a collective mode. The peak at 190  cm^{-1} (23.6 meV) is presumably another collective mode since the line is symmetric and its energy is significantly below the gap energy observed by single-particle spectroscopies. Given the experimental band structure of (Li_{1-x}Fe_{x})OHFeSe, the most plausible explanations include conventional spin-fluctuation pairing between the electron bands and the incipient hole band and pairing between the hybridized electron bands. The absence of gap features in A_{1g} and B_{2g} symmetry favors the second case. Thus, in spite of various differences between the pnictides and chalcogenides, this Letter demonstrates the proximity of pairing states and the importance of band structure effects in the Fe-based compounds.

Universal scaling of weak localization in graphene due to bias-induced dispersion decoherence

The differential conductance of graphene is shown to exhibit a zero-bias anomaly at low temperatures, arising from a suppression of the quantum corrections due to weak localization and electron interactions. A simple rescaling of these data, free of any adjustable parameters, shows that this anomaly exhibits a universal, temperature- (T) independent form. According to this, the differential conductance is approximately constant at small voltages (V < kBT/e), while at larger voltages it increases logarithmically with the applied bias. For theoretical insight into the origins of this behaviour, which is inconsistent with electron heating, we formulate a model for weak-localization in the presence of nonequilibrium transport. According to this model, the applied voltage causes unavoidable dispersion decoherence, which arises as diffusing electron partial waves, with a spread of energies defined by the value of the applied voltage, gradually decohere with one another as they diffuse through the system. The decoherence yields a universal scaling of the conductance as a function of eV/kBT, with a logarithmic variation for eV/kBT > 1, variations in accordance with the results of experiment. Our theoretical description of nonequilibrium transport in the presence of this source of decoherence exhibits strong similarities with the results of experiment, including the aforementioned rescaling of the conductance and its logarithmic variation as a function of the applied voltage.

Effects of wet atmospheric nitrogen deposition on epiphytic lichens in the subtropical forests of Central China: Evaluation of the lichen food supply and quality of two endangered primates

Over the last few decades, the threat posed to biodiversity and ecosystem function by atmospheric nitrogen (N) deposition has been increasingly recognized. The disturbed nutrient balance and species composition of plants induced by higher N deposition can impact the biodiversity of the organisms that consume the plants. In this research, we implemented several experiments to estimate the effects of increased N deposition on the growth, survival, and nutrients of the dominant epiphytic lichens in the subtropical mountains in Central China to assess the lichen food amount and nutritional quality for two endangered primates endemic to China. Our results indicated that the thallus growth and propagule survival of the lichens were significantly decreased when nitrogen addition changed from 6.25 to 50.0 kg N·ha^-1·y^-1; it was also shown that lichen biomass could be decreased by 11.2%-70.2% when the deposition addition exceeded 6.25 kg N·ha^-1·y^-1. Further, our study revealed that increased nitrogen deposition also reduced the nutritional quality of the lichens via reducing the soluble protein and soluble sugar levels and increasing the fiber content, which would substantially affect the diet selection of the plants consumers in the region, particularly the populations of the two lichen-eating endangered primate species, Rhinopithecus roxellana and R. bieti. Our experimental study suggested that the nitrogen pollution derived from anthropogenic activities could cause cascading effects for the whole forest ecosystem of Central China; thus, more studies about nitrogen deposition in this region are required.

Cisplatin in Combination with MDM2 Inhibition Downregulates Rad51 Recombinase in a Bimodal Manner to Inhibit Homologous Recombination and Augment Tumor Cell Kill

Dysfunction of p53 and resistance to cancer drugs can arise through mutually exclusive overexpression of MDM2 or MDM4. Cisplatin-resistant cells, however, can demonstrate increased binding of both MDM2 and MDM4 to p53 but in absence of cellular overexpression. Whether MDM2 inhibitors alone can activate p53 in these resistant cells was investigated with the goal to establish the mechanism for potential synergy with cisplatin. Thus, growth inhibition by individual drugs and combinations was assessed by a colorimetric assay. Drug-treated parental A2780 and resistant tumor cells were also examined for protein expression using immunoblot and reverse phase protein array (RPPA) and then subjected to Ingenuity Pathway Analysis (IPA). Gene expression was assessed by real-time polymerase chain reaction, DNA damage by confocal microscopy, cell cycle by flow cytometry, and homologous recombination (HR) by a GFP reporter assay. Our results demonstrate that Nutlin-3 but not RITA (reactivation of p53 and induction of tumor cell apoptosis) effectively disrupted the p53-MDM2-MDM4 complex to activate p53, which increased robustly with cisplatin/Nutlin-3 combination and enhanced antitumor effects more than either agent alone. RPPA, IPA, and confocal microscopy provided evidence for an "apparent" increase in DNA damage resulting from HR inhibition by cisplatin/Nutlin-3. Molecularly, the specific HR protein Rad51 was severely downregulated by the combination via two mechanisms: p53-dependent transrepression and p53/MDM2-mediated proteasomal degradation. In conclusion, Nutlin-3 fully destabilizes the p53-MDM2-MDM4 complex and synergizes with cisplatin to intensify p53 function, which then downregulates Rad51 through a bimodal mechanism. As a result, HR is inhibited and antitumor activity enhanced in otherwise HR-proficient sensitive and resistant tumor cells. SIGNIFICANCE STATEMENT: Rad51 downregulation by the combination of cisplatin and Nutlin-3 inhibits homologous recombination (HR), which leads to persistence in DNA damage but not an increase. Thus, inhibition of HR enhances antitumor activity in otherwise HR-proficient sensitive and resistant tumor cells.

Abstract NT-109: VAL-083 (DIANHYDROGALACTITOL) SYNERGIZES WITH PARP INHIBITORS IN BRCA-PROFICIENT AND BRCA-DEFICIENT OVARIAN CANCER MODELS

BACKGROUND: Ovarian cancer is normally treated with platinum (Pt)-based chemotherapy, but patients frequently develop Pt-resistance. Dysfunctional p53 is implicated in Pt-resistance, comprising a therapeutic challenge in high grade serous ovarian carcinoma (HGSC), where p53 is universally mutated (96%). Attempts to overcome Pt-resistance in HGSC include agents blocking the DNA repair pathways, most notably the PARP inhibitors (PARPi), leading to the accumulation of DNA double strand breaks (DSBs) and cancer cell death. Sensitivity to PARPi is correlated with deficiencies in the homologous recombination (HR) DNA repair system, which is in charge of accurately repairing DSBs. BRCA1 and BRCA2 are key proteins in HR, and mutated BRCA1/2 (present in 20% of HGSC) are well-established biomarkers for PARPi sensitivity. PARPi treatment of Pt-sensitive gynecologic malignancies have improved progression free survival (PFS); however, improvements in overall survival have not been achieved and a 5-year survival rate of only 40% remains in ovarian cancer. Additionally, resistance to PARPi in the clinical setting is emerging as a significant medical challenge. VAL-083 is a first-in-class bifunctional DNA damaging agent with demonstrated clinical activity against a range of cancers, including ovarian. VAL-083 rapidly induces interstrand cross-links at guanine-N7 leading to DSBs, activation of the HR repair pathway and cancer cell death. Notably, VAL-083 induces cell death through two parallel pathways - one p53-independent and one p53-dependent. We have shown that VAL-083 is able to overcome cisplatin-resistance in a panel of ovarian cancer in vitro models, independent of p53 status. We have also shown that VAL-083 maintains activity independent of prominent DNA repair mechanisms such as O6-methylguanine DNA methyltransferase (MGMT), non-homologous end-joining (NHEJ) and mismatch repair (MMR) implicated in resistance to numerous chemotherapeutics, including cisplatin and PARPi. Cancer cells thus rely heavily on functional HR pathway for repair of VAL-083-induced DSBs. This suggests combination therapy with agents further inducing DSBs or blocking their repair, including PARPi. Taken together, these data propose VAL-083's potential for targeting Pt-resistant HGSC and for combination treatment with PARPi.

METHODS: In this study, we examined the cytotoxicity of VAL-083 in combination with PARPi (olaparib, niraparib, rucaparib, veliparib or talazoparib) against HR-proficient and HR-impaired ovarian cancer cells. VAL-083 cytotoxicity alone and in combination with PARPi was investigated using the 5-day MTT assay in HR-proficient (control siRNA) and HR-impaired (BRCA1 siRNA knockdown) A2780 ovarian cancer cells. RESULTS: We report increased VAL-083 cytotoxicity against HR-impaired A2780 cancer cells. We further report synergy between VAL-083 and PARPi olaparib, talazoparib and niraparib in both HR-proficient and HR-deficient settings. VAL-083 combination with rucaparib produced synergistic cytotoxicity in the HR-deficient setting, while VAL-083 combination with veliparib was no more than additive. These data demonstrate that VAL-083 can synergize with some PARP inhibitors in both a HR-proficient and HR-deficient setting.

CONCLUSION: Our results demonstrate a distinct DNA damaging mechanism for VAL-083, resulting in the ability to overcome cisplatin-resistance, target HR-impaired tumors and overcome MGMT, MMR and NHEJ-related chemoresistance. In addition, VAL-083 synergized with several PARPi, particularly olaparib, rucaparib and talazoparib, in both HR-proficient and HR-deficient ovarian tumor cells.

Citation Format: Anne Steino, Guangan He, Jeffrey Bacha, Dennis M. Brown and Zahid H. Siddik. VAL-083 (DIANHYDROGALACTITOL) SYNERGIZES WITH PARP INHIBITORS IN BRCA-PROFICIENT AND BRCA-DEFICIENT OVARIAN CANCER MODELS [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr NT-109.

Isolation of H8N4 avian influenza virus from wild birds in Shanghai, China

The H8 subtype viruses are rarely isolated from wild ducks. Shanghai is one of the important wintering or stopover sites on the East Asia-Australia Migration Flyway. An influenza virus, subtype H8N4, was firstly isolated from a common teal (Anas crecca) in Shanghai during 2017-2018 in this study. To clarify the genetic characteristics of the H8N4 virus, the whole genome sequences were analyzed. Phylogenetic analysis of the hemagglutinin and neuraminidase genes showed that they shared highest nucleotide identity (99.19%-99.64%) with the Japan duck-origin H8N4 virus collected in 2016 (A/duck/Aichi/231003/2016) and belonged to the Eurasian-like avian lineage. Six other genes of the H8N4 isolated virus were all highly similar to the corresponding genes of a wide range of AIV subtypes including H9N2, H5N7, H3N8, H1N2, H4N6 and H1N1. The results indicated that the H8N4 virus was a multiple reassortant virus. The study emphasized that the continuous surveillance of influenza virus in wild birds should be strengthened. Keywords: avian influenza virus; H8N4; phylogenetic analysis; Shanghai.

PTGER3 induces ovary tumorigenesis and confers resistance to cisplatin therapy through up-regulation Ras-MAPK/Erk-ETS1-ELK1/CFTR1 axis

Background

Inflammatory mediator prostaglandin E2–prostaglandin E2 receptor EP3 (PTGER3) signaling is critical for tumor-associated angiogenesis, tumor growth, and chemoresistance. However, the mechanism underlying these effects in ovarian cancer is not known.

Methods

An association between higher tumoral expression of PTGER3 and shorter patient survival in the ovarian cancer dataset of The Cancer Genome Atlas prompted investigation of the antitumor effects of PTGER3 downmodulation. PTGER3 mRNA and protein levels were higher in cisplatin-resistant ovarian cancer cells than in their cisplatin-sensitive counterparts.

Findings

Silencing of PTGER3 via siRNA in cancer cells was associated with decreased cell growth and less invasiveness, as well as cell-cycle arrest and increased apoptosis, mediated through the Ras-MAPK/Erk-ETS1-ELK1/CFTR1 axis. Furthermore, sustained PTGER3 silencing with multistage vector and liposomal 2’-F-phosphorodithioate-siRNA–mediated silencing of PTGER3 combined with cisplatin resulted in robust antitumor effects in cisplatin-resistant ovarian cancer models.

Interpretation

These findings identify PTGER3 as a potential therapeutic target in chemoresistant ovarian cancers expressing high levels of this oncogenic protein.

Fund

National Institutes of Health/National Cancer Institute, USA.