Nonfuel Antineutrino Contributions in the High Flux Isotope Reactor

Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of ν ¯ e is important when making theoretical predictions. One source of ν ¯ e that is often neglected arises from the irradiation of the nonfuel materials in reactors. The ν ¯ e rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible ν ¯ e sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the ν ¯ e source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel ν ¯ e contributions from HFIR to PROSPECT amount to 1% above the inverse beta decay threshold with a maximum contribution of 9% in the 1.8-2.0 MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel ν ¯ e contribution.

First Measurement of Differential Charged Current Quasielasticlike ν_{μ}-Argon Scattering Cross Sections with the MicroBooNE Detector

We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino (ν_{μ}) scattering on argon with a muon and a proton in the final state, ^{40}Ar (ν_{μ},μp)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59×10^{19} protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e., for interactions leading to a muon, one proton, and no pions above detection threshold) of (4.93±0.76_{stat}±1.29_{sys})×10^{-38}  cm^{2}, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low-momentum-transfer events.

Abstract 2586: Identification of cancer-associated RhoA mutants and analogous K-Ras mutants that induce gain-of function despite low GTP binding

While the Ras GTPases are frequently mutated, especially at codons 12, 13, or 61, the structurally related Rho GTPases, although they are implicated in tumor invasion and metastasis, are rarely mutated in solid tumors, except for diffuse gastric cancer. The vast majority of cancer-associated RHO mutations are not located in codons 14, 15, or 63, which correspond to the 3 canonical mutant Ras codons. Here we have evaluated the biological and biochemical phenotypes of several cancer-associated RhoA mutants, which indicated that some RhoA mutants have unusual phenotypes and therefore prompted us to generalize our findings to other small GTPases by constructing and analyzing the analogous mutants in K-Ras.

We constructed 8 cancer-associated RhoA mutants from the TCGA database, and found that each was gain-of-function biologically. Using the Rhotekin binding assay to infer RhoGTP levels, 5 mutants (Y42C, L57V, D59G, A61D, D76G), had higher binding than WT RhoA. However, 3 mutants (G62E. L69P and L69R) did not bind Rhotekin, but did bind strongly to Citron, a Rho-dependent kinase implicated in cytokinesis and cell cycle regulation. Because the three mutants were highly transforming, we directly determined GTP/GDP binding levels, the “gold-standard” assay, for all mutants, which indicated G62E had high GTP-binding and low GDP-binding, in contrast to its negative binding to Rhotekin, while L69P and L69R had high GDP-binding and low GTP-binding similar to WT. Purified GDP-bound L69P and L69R formed a complex with Citron more efficiently than did WT GTP-bound or GDP-bound RhoA. Endogenous Citron and CDK1 contribute to anchorage-independent growth, as siRNA knockdown of either gene in lines transformed by G62E, L69R or L69P inhibited this phenotype.

The cancer-associated K-Ras mutants G60E and M67L (which correspond to RhoA G62E and L69R) and also K-Ras M67R displayed gain-of-function biologically, and the GTP/GDP-binding phenotype of each was analogous to the respective RhoA mutant: high GTP-binding for G60E, and low Raf-RBD binding and high GDP-binding for M67L and M67R. The low GTP K-Ras mutants bound more strongly to the RBD domain of Ras effectors other than Raf, resulting in activation of RAP and AKT in transfected cells. Our microarray data revealed that these GDP-bound mutant K-Ras or RhoA can up-regulate cell-cycle progression genes and down-regulate tumor suppressor genes compared to WT, which may account for their transforming phenotype.

We conclude that some cancer-associated RhoA mutants are transforming when GDP-bound, a phenotype that has not been described for any small GTPase. The equivalent K-Ras mutants display a similar phenotype, which implies the findings should be extrapolatable to many small GTPases. Such mutants can be strongly transforming, although they only bind a subset of preferred downstream effectors and activate their respective pathways. In addition, the widely used Rhotekin binding assay to infer RhoGTP levels may give misleading results for some mutants.

Citation Format: Xiaolan Qian, Alex Papageorge, Dunrui Wang, Brajendra Tripathi, Yucheng Gao, Marian Durkin, Beatriz Sanchez-Solana, Dominic Esposito, Timothy Waybright, Andrew Stephen, Douglas R. Lowy. Identification of cancer-associated RhoA mutants and analogous K-Ras mutants that induce gain-of function despite low GTP binding [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2586.

Abstract 2137: A high proportion of protein phosphorylation sites identified in CPTAC breast cancer and lung adenocarcinoma may result from direct phosphorylation by CDK1

Cyclin-dependent kinase 1 (CDK1) is a serine/threonine kinase that drives the G2/M phase of the cell cycle, and increased CDK1 kinase activity is a frequent feature of several tumor types. In the current study, we have used the National Cancer Institute's Clinical Proteomic Tumor Analysis Consortium (CPTAC) datasets to identify potential target phosphorylation sites associated with CDK1 activity in breast and lung adenocarcinoma and to experimentally study some of their biologic effects. Among the global protein phosphorylation sites detected in CPTAC, 80% and 81% of the identified phosphorylation sites in breast cancer and lung adenocarcinoma were found to correlate well with the level of an activating phosphorylation site in CDK1, t161. Positive correlations (r > 0.6) were present in most paired samples of tumor tissue and normal tissue. In addition, 42% and 40% of all phosphorylation sites in both of these tumor types were found to contain the minimum CDK1 consensus motif Ser/Thr-Pro (S/T-P). This result suggests that many of the sites with this motif are directly phosphorylated by CDK1, while most of the sites that lack this sequence are likely to be phosphorylated by other kinases. In both tumor types, increased phosphorylation of proteins in several signaling pathways, including those for glycolysis and the cell cycle, were found to be associated with phosphorylation of CDK1 t161. To study a possible direct effect of CDK1-dependent phosphorylation on a protein involved in cell cycle progression, we selected Epithelial Cell Transforming 2 (ECT2), which is a Rho family-specific GEF (guanine nucleotide exchange factor) with a role in G2/M. In agreement with the proteomic data, mass spectrometry analysis showed elevated ECT2 phosphorylation on T359, S367, T373, S376 and S861 in the G2/M phase that was sensitive to treatment with a CDK1 inhibitor. Biological experiments confirmed that phosphorylation of these sites enhanced the pro-oncogenic and GEF activity of ECT2. Additional experimental mechanistic analysis is needed to demonstrate whether specific phosphorylations are attributable to direct or indirect effects of CDK1.

Citation Format: Dunrui Wang, Xiaolan Qian, Sarah Eng, Lisa Jenkins, Marian Durkin, Douglas Lowy. A high proportion of protein phosphorylation sites identified in CPTAC breast cancer and lung adenocarcinoma may result from direct phosphorylation by CDK1 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2137.

Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments

Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{μe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Δm_{41}^{2}, excluding the 90% C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90% CL_{s} for Δm_{41}^{2}<13  eV^{2}. Furthermore, the LSND and MiniBooNE 99% C.L. allowed regions are excluded at 99% CL_{s} for Δm_{41}^{2}<1.6 eV^{2}.

Cancer-Associated Point Mutations in the DLC1 Tumor Suppressor and Other Rho-GAPs Occur Frequently and Are Associated with Decreased Function

In advanced cancer, the RHOA GTPase is often active together with reduced expression of genes encoding Rho-specific GTPase-accelerating proteins (Rho-GAP), which negatively regulate RHOA and related GTPases. Here we used the The Cancer Genome Atlas dataset to examine 12 tumor types (including colon, breast, prostate, pancreas, lung adenocarcinoma, and squamous cell carcinoma) for the frequency of codon mutations of 10 Rho-GAP and experimentally tested biochemical and biological consequences for cancer-associated mutants that arose in the DLC1 tumor suppressor gene. DLC1 was the Rho-GAP gene mutated most frequently, with 5%-8% of tumors in five of the tumor types evaluated having DLC1 missense mutations. Furthermore, 20%-26% of the tumors in four of these five tumor types harbored missense mutations in at least one of the 10 Rho-GAPs. Experimental analysis of the DLC1 mutants indicated 7 of 9 mutants whose lesions were located in the Rho-GAP domain were deficient for Rho-GAP activity and for suppressing cell migration and anchorage-independent growth. Analysis of a DLC1 linker region mutant and a START domain mutant showed each was deficient for suppressing migration and growth in agar, but their Rho-GAP activity was similar to that of wild-type DLC1. Compared with the wild-type, the linker region mutant bound 14-3-3 proteins less efficiently, while the START domain mutant displayed reduced binding to Caveolin-1. Thus, mutation of Rho-GAP genes occurs frequently in some cancer types and the majority of cancer-associated DLC1 mutants evaluated were deficient biologically, with various mechanisms contributing to their reduced activity. SIGNIFICANCE: These findings indicate that point mutation of Rho-GAP genes is unexpectedly frequent in several cancer types, with DLC1 mutants exhibiting reduced function by various mechanisms.

miR-485-5p improves the progression of ovarian cancer by targeting SRC in vitro and in vivo

miR-485-5p is involved in many tumors, but its role in ovarian cancer has been rarely reported. This paper mainly studied the expression and mechanism of miR-485-5p in ovarian cancer. The expression of miR-485-5p in ovarian cancer was compared with that in adjacent tissues, and the expression of miR-485-5p in various ovarian cancer cell lines was detected by RT-PCR. miR-485-5p mimics and pcDNA plasmid or pcDNA-SRC were transfected into SKOV3 cells. Cell proliferation was detected by CCK-8, cell cycle and apoptosis were detected by flow cytometry, and cell migration and invasion were detected by wound assay and transwell assay. Nude mice were inoculated with SKOV3 cells to detect the effect of miR-485-5p on xenograft. SRC and its downstream proteins were detected by western blot. Our data suggested that the expression of miR-485-5p was low in ovarian cancer tissues and ovarian cancer cell lines. miR-485-5p mimics can inhibit the proliferation, migration, invasion, and the induction of cycle arrest and apoptosis of SKOV3 cells in vivo and in vitro, and pcDNA-SRC can reverse the effect of miR-485-5p mimics on ovarian cancer. Our findings suggest that miR-485-5p could inhibit the progression of ovarian cancer by targeting SRC, which might be a new target for ovarian cancer therapy as the SRC inhibitor.

[Genomic analysis of a 2019-novel coronavirus (2019-nCoV) strain in the first COVID-19 patient found in Hangzhou]

Objective: To understand the viral genomic characteristics of a 2019-novel coronavirus (2019-nCoV) strain in the first COVID-19 patient found in Hangzhou, China. Methods: Viral RNA was extracted in throat swab and sputum sample of the patient and was performed real-time reverse transcription PCR detection and obtained viral genome by high-throughput sequencing method. Phylogenetic analysis was conducted using 29 2019-nCoV genomes and 30 β-coronavirus genomes deposited in NCBI GenBank. Fifteen genomes from Wuhan were grouped by mutation sites and others were identified by Wuhan's or specific mutation sites. Results: A 29 833 bp length genome of the first 2019-nCoV strain in Hangzhou was obtained, covering full length of the coding regions of coronavirus. Phylogenetic analysis showed that the genome was closest to the genome of a bat SARS-like coronavirus strain RaTG13 with an identity of 96.11% (28 666/29 826). Among the genes between two genomes, E genes were highly conserved (99.56%), while S genes had lowest identity (92.87%). The genome sequence similarities among 29 strains from China (Hangzhou, Wuhan, and Shenzhen), Japan, USA, and Finland, were all more than 99.9%; however, some single nucleotide polymorphisms were identified in some strains. Conclusion: The genome of Hangzhou 2019-nCoV strain was very close to the genomes of strains from other cities in China and overseas collected at early epidemic phase. The 2019-nCoV genome sequencing method used in this paper provides an useful tool for monitoring variation of viral genes.

Association of obesity with bone mineral density and osteoporosis in adults: a systematic review and meta-analysis

OBJECTIVES

Results from previous studies investigating the association of obesity with bone mineral density (BMD) and osteoporosis (OP) are inconsistent. The purpose of the present study was to examine whether obesity is associated with BMD and the risk of OP.

STUDY DESIGN

This is a meta-analysis.

METHODS

A computerised literature search was conducted using the PubMed, Web of Science, China National Knowledge Internet (CNKI) (Chinese) and Wanfang (Chinese) databases for relevant articles published in English or Chinese before the end of December 2017. Means with standard deviations and odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) were computed to estimate the association between obesity and BMD and the risk of OP by using a random-effects model. In addition, a heterogeneity test and sensitivity analysis were conducted.

RESULTS

Adults with obesity had higher BMD than healthy-weight subjects in both the lumbar spine and femoral neck measurement sites. Obesity was positively related to BMD in the two sites, with merged weighted mean difference (WMD) of 0.07 g/cm² in the lumbar spine (95% CI: 0.045, 0.095; P < 0.001; P_{heterogeneity} <0.001; I² = 89.1%) and WMD of 0.087 g/cm² in the femoral neck (95% CI: 0.063, 0.112; P < 0.001; P_{heterogeneity} <0.001; I² = 92.8%). General obesity was negatively related to femoral neck OP, indicating that obesity is a protective factor for OP, with a merged OR of 0.169 (95% CI: 0.132, 0.216; P < 0.001; P_{heterogeneity} = 0.716; I² = 0.0%).

CONCLUSIONS

Adults with obesity had significantly higher BMD than healthy-weight adults. Obesity was positively associated with BMD and negatively correlated with OP.

Immunotherapeutics for head and neck squamous cell carcinoma stem cells

Cancer stem cell (CSC)-related therapy resistance has become a new obstacle to the successful application of cancer treatment and head and neck squamous cell carcinoma (HNSCC) is no exception to this finding. Head and neck squamous cell carcinoma is highly immune-suppressive, and recently the immune suppression and invasion of HNSCC-CSCs have been characterized. These characteristics have received research and clinical attention because they would enable the stratification of patients into specific cancer subtypes and, consequently, the establishment of new therapeutic approaches with improved efficacy. This review discusses the feasibility of CSC-targeted strategies and their incorporation with nanotechnology to improve the efficacy of cancer immunotherapy.

Correlations and incipient antiferromagnetic order within the linear Mn chains of metallic Ti4MnBi2

We report measurements on Ti4MnBi2, where a crystal structure involving linear chains of Mn ions suggests one-dimensional magnetic character. The electrical resistivity is metallic, consistent with the results of electronic-structure calculations that find a robust Fermi surface albeit with moderate electronic correlations. A Curie-Weiss fit to the magnetic susceptibility suggests that the Mn moments are in the low-spin S = 1/2 configuration. Neutron diffraction measurements detect weak antiferromagnetic order within the Mn chains, with further evidence for the small staggered moment coming from the entropy associated with the ordering peak in the specific heat as well as from the results of spin-polarized electronic-structure calculations. The antiferromagnetic moments are apparently associated with thed x 2 - y 2 and d xy orbitals of Mn while the remaining Mn orbitals are delocalized and nonmagnetic. Strong quantum fluctuations, possibly related to an electronic instability that forms the Mn moment or to the one-dimensional character of Ti4MnBi2, nearly overcome magnetic order.

First Measurement of Inclusive Muon Neutrino Charged Current Differential Cross Sections on Argon at E_{ν}∼0.8 GeV with the MicroBooNE Detector

We report the first measurement of the double-differential and total muon neutrino charged current inclusive cross sections on argon at a mean neutrino energy of 0.8 GeV. Data were collected using the MicroBooNE liquid argon time projection chamber located in the Fermilab Booster neutrino beam and correspond to 1.6×10^{20} protons on target of exposure. The measured differential cross sections are presented as a function of muon momentum, using multiple Coulomb scattering as a momentum measurement technique, and the muon angle with respect to the beam direction. We compare the measured cross sections to multiple neutrino event generators and find better agreement with those containing more complete treatment of quasielastic scattering processes at low Q^{2}. The total flux integrated cross section is measured to be 0.693±0.010(stat)±0.165(syst)×10^{-38}  cm^{2}.

Extraction of the ^{235}U and ^{239}Pu Antineutrino Spectra at Daya Bay

This Letter reports the first extraction of individual antineutrino spectra from ^{235}U and ^{239}Pu fission and an improved measurement of the prompt energy spectrum of reactor antineutrinos at Daya Bay. The analysis uses 3.5×10^{6} inverse beta-decay candidates in four near antineutrino detectors in 1958 days. The individual antineutrino spectra of the two dominant isotopes, ^{235}U and ^{239}Pu, are extracted using the evolution of the prompt spectrum as a function of the isotope fission fractions. In the energy window of 4-6 MeV, a 7% (9%) excess of events is observed for the ^{235}U (^{239}Pu) spectrum compared with the normalized Huber-Mueller model prediction. The significance of discrepancy is 4.0σ for ^{235}U spectral shape compared with the Huber-Mueller model prediction. The shape of the measured inverse beta-decay prompt energy spectrum disagrees with the prediction of the Huber-Mueller model at 5.3σ. In the energy range of 4-6 MeV, a maximal local discrepancy of 6.3σ is observed.

SRC and ERK cooperatively phosphorylate DLC1 and attenuate its Rho-GAP and tumor suppressor functions

DLC1 controls focal adhesion dynamics and other processes that suppress tumorigenesis; therefore, it is unclear why some cancers maintain high levels of DLC1. Tripathi et al. show that phosphorylation of DLC1 by SRC and ERK mitigates DLC1’s tumor suppressor activities but these can be reactivated by kinase inhibition as a potential cancer treatment.

SRC and ERK kinases control many cell biological processes that promote tumorigenesis by altering the activity of oncogenic and tumor suppressor proteins. We identify here a physiological interaction between DLC1, a focal adhesion protein and tumor suppressor, with SRC and ERK. The tumor suppressor function of DLC1 is attenuated by phosphorylation of tyrosines Y451 and Y701 by SRC, which down-regulates DLC1’s tensin-binding and Rho-GAP activities. ERK1/2 phosphorylate DLC1 on serine S129, which increases both the binding of SRC to DLC1 and SRC-dependent phosphorylation of DLC1. SRC inhibitors exhibit potent antitumor activity in a DLC1-positive transgenic cancer model and a DLC1-positive tumor xenograft model, due to reactivation of the tumor suppressor activities of DLC1. Combined treatment of DLC1-positive tumors with SRC plus AKT inhibitors has even greater antitumor activity. Together, these findings indicate cooperation between the SRC, ERK1/2, and AKT kinases to reduce DLC1 Rho-GAP and tumor suppressor activities in cancer cells, which can be reactivated by the kinase inhibitors.

[Review on preconception cohort studies in China]

The preconception cohort is of great importance to explore and analyze the impact of multiple factors before and during pregnancy on human reproductive health, pregnancy outcomes and offspring health. This paper summarizes the information and characteristics of the preconception cohort studies in recent years in China.

Abstract 1762: The START domain of the DLC1 tumor suppressor binds phosphatidylserine and two proteins, PLCD1 and Caveolin-1

The tumor suppressor gene DLC1 encodes a multi-domain protein, which includes a Rho-GAP domain (Rho GTPase activating protein domain) that negatively regulates the activity of RhoA, B, and C, and has been hypothesized to be the basis of its tumor suppressor functions. DLC1 also contains a less well characterized START (StAR-related lipid transfer) domain in its C-terminus, whose overall contribution to DLC1 function remains incompletely understood. START domains in other proteins have been shown to bind lipids, but no lipid has yet been identified that binds the DLC1 START domain. In the present study, we attempted to gain further insight into the molecular function and lipid binding properties of the DLC1 START domain.

We previously determined that Caveolin-1, the main structural component and marker of caveolae, interacts with the DLC1 START domain, and this interaction contributes to the full tumor suppressor activity of DLC1. In unpublished studies, we additionally identified Phospholipase C delta 1 (PLCD1), which participates in intracellular Ca2+ mobilization, forming a complex with the DLC1 START domain and with Caveolin-1.

We have now developed evidence that, in addition to binding Caveolin-1 and PLCD1, the DLC1 START domain binds a lipid, phosphatidylserine (PS), and have identified a colon cancer-associated DLC1-START domain mutant (R947C) that results in a protein deficient in forming a complex with all three binding partners and displays reduced tumor suppressor activity but intact RhoGAP activity. The interaction between the DLC1-START domain and PS can occur independently of PLCD1 and/or Caveolin-1, but PS promotes complex formation between the DLC1 START domain and PLCD1 or Caveolin-1, without altering PLCD1 to Caveolin-1 binding. Biological assays with wild type DLC1 show cooperation between DLC1 and PLCD1 or Caveolin-1 to inhibit cell migration, but no cooperation is observed when all three genes are overexpressed, suggesting that Caveolin-1 and PLCD1 occupy the same migration signaling pathway. Thus, we have identified a biologically relevant complex between DLC1 and three macromolecules (PLCD1, PS and Caveolin-1) that contributes to the full tumor suppressor function of DLC1 independently of its RhoGAP activity, and are testing the hypothesis that PS serves as a linker between the DLC1 START domain and PLCD1 or Caveolin-1.

Citation Format: Beatriz Sanchez-Solana, Dunrui Wang, Xiaolan Qian, Alex Papageorge, Parthibane Velayoudame, Jairaj Acharya, Douglas R. Lowy. The START domain of the DLC1 tumor suppressor binds phosphatidylserine and two proteins, PLCD1 and Caveolin-1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1762.

Abstract 4235: Phosphorylation of Serine 861 in the ECT2 guanine nucleotide exchange factor activates Rho family GTPases and is a biomarker for several tumor types

The Rho family of GTPases, which cycle between inactive GDP-bound and active GTP-bound states, have high activity in many cancers. One mechanism for their activation is by guanine nucleotide exchange factors (GEFs), which stimulate the replacement of GDP-bound Rho with GTP-bound Rho. In this study, we report phosphorylation of Epithelial Cell Transforming 2 (ECT2), which is a Rho family-specific GEF, is a biomarker in several tumor types, based on bioinformatic analysis and biological assays. Our analysis of the NCI Clinical Proteomic Tumor Analysis Consortium (CPTAC) database found that Serine 861 (S861) in ECT2 is more highly phosphorylated in several tumor types compared to its phosphorylation in the relevant normal tissue. S861 phosphorylation is 2.1-fold and 2.4-fold higher in colon cancer and ovarian cancer, respectively, and high S861 phosphorylation in breast cancer is correlated with a poorer prognosis. Phosphorylation of S861 is especially high in triple-negative breast cancer, as it is 2.3-fold higher in this type compared with the other types of breast cancer. Increased phosphorylation of S861 is associated increased ECT2 mRNA and protein levels in colon cancer and breast cancer. In experimental studies, siRNA knockdown of endogenous ECT2 in two triple-negative breast cancer lines resulted in lower levels of RhoA-GTP, Rac-GTP, and Cdc42-GTP, and led to reduced cell migration, cell proliferation, and anchorage-independent growth, suggesting that ECT2 is a key regulator of cellular signaling and oncogenic growth in the triple-negative lines. Conversely, ectopic expression of wild-type ECT2 induced increased levels of RhoA-GTP, Rac-GTP, and Cdc42-GTP and promoted migration, proliferation, and anchorage-independent growth. Compared with wild type ECT2, ectopic expression of ECT2 carrying a phospho-defective (S861A) or phospho-mimic (S861D) mutation, respectively, reduced or enhanced ECT2 GEF and biological activities. Our results indicate that phosphorylation of S861 enhances the pro-oncogenic activity of ECT2, which is correlated with the increased phosphorylation of S861 in the three cancer types, the increased expression of ECT2 in two of these cancer types, and the prognostic significance of S861 phosphorylation in breast cancer. * Dunrui Wang and Xiaolan Qian are Equal contributors

Citation Format: Dunrui Wang, Xiaolan Qian, Sarah Eng, Shivani Nellore, Alex G. Papageorge, Douglas R. Lowy. Phosphorylation of Serine 861 in the ECT2 guanine nucleotide exchange factor activates Rho family GTPases and is a biomarker for several tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4235.

Measurement of the Antineutrino Spectrum from ^{235}U Fission at HFIR with PROSPECT

This Letter reports the first measurement of the ^{235}U ν[over ¯]_{e} energy spectrum by PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, operating 7.9 m from the 85  MW_{th} highly enriched uranium (HEU) High Flux Isotope Reactor. With a surface-based, segmented detector, PROSPECT has observed 31678±304(stat) ν[over ¯]_{e}-induced inverse beta decays, the largest sample from HEU fission to date, 99% of which are attributed to ^{235}U. Despite broad agreement, comparison of the Huber ^{235}U model to the measured spectrum produces a χ^{2}/ndf=51.4/31, driven primarily by deviations in two localized energy regions. The measured ^{235}U spectrum shape is consistent with a deviation relative to prediction equal in size to that observed at low-enriched uranium power reactors in the ν[over ¯]_{e} energy region of 5-7 MeV.

Effects of DLC1 Deficiency on Endothelial Cell Contact Growth Inhibition and Angiosarcoma Progression

Background

Deleted in Liver Cancer 1 (DLC1) is a tumor suppressor gene frequently deleted in cancer. However, DLC1 is not known to be deleted in angiosarcoma, an aggressive malignancy of endothelial cell derivation. Additionally, the physiologic functions of DLC1 protein in endothelial cells are poorly defined.

Methods

We investigated the effects of shRNA-induced DLC1 depletion in endothelial cells. Cell growth was measured by 3H thymidine incorporation, IncuCyte imaging, and population doublings; cell death by cell cycle analysis; gene expression by Affimetrix arrays and quantitative polymerase chain reaction; NF-κB activity by reporter assays; and protein levels by immunoblotting and immunofluorescence staining. We tested Tanespimycin/17-AAG and Fasudil treatment in groups of nine to 10 mice bearing ISOS-1 angiosarcoma. All statistical tests were two-sided.

Results

We discovered that DLC1 is a critical regulator of cell contact inhibition of proliferation in endothelial cells, promoting statistically significant (P < .001) cell death when cells are confluent (mean [SD] % viability: control DLC1 = 15.6 [19.3]; shDLC1 = 73.4 [13.1]). This prosurvival phenotype of DLC1-depleted confluent endothelial cells is attributable to a statistically significant and sustained increase of NF-κB activity (day 5, P = .001; day 8, P = .03) associated with increased tumor necrosis factor alpha-induced protein 3 (TNFAIP3/A20) signaling. Consistently, we found that DLC1 is statistically significantly reduced (P < .001 in 5 of 6) and TNFAIP3/A20 is statistically significantly increased (P < .001 in 2 of 3 and P = 0.02 in 1 of 3) in human angiosarcoma compared with normal adjacent endothelium. Treatment with the NF-κB inhibitor Tanespimycin/17-AAG statistically significantly reduced angiosarcoma tumor growth in mice (treatment tumor weight vs control, 0.50 [0.19] g vs 0.91 [0.21] g, P = .001 experiment 1; 0.66 [0.26] g vs 1.10 [0.31] g, P = .01 experiment 2).

Conclusions

These results identify DLC1 as a previously unrecognized regulator of endothelial cell contact inhibition of proliferation that is depleted in angiosarcoma and support NF-κB targeting for the treatment of angiosarcoma where DLC1 is lost.

First Search for Short-Baseline Neutrino Oscillations at HFIR with PROSPECT

This Letter reports the first scientific results from the observation of antineutrinos emitted by fission products of ^{235}U at the High Flux Isotope Reactor. PROSPECT, the Precision Reactor Oscillation and Spectrum Experiment, consists of a segmented 4 ton ^{6}Li-doped liquid scintillator detector covering a baseline range of 7-9 m from the reactor and operating under less than 1 m water equivalent overburden. Data collected during 33 live days of reactor operation at a nominal power of 85 MW yield a detection of 25 461±283 (stat) inverse beta decays. Observation of reactor antineutrinos can be achieved in PROSPECT at 5σ statistical significance within 2 h of on-surface reactor-on data taking. A reactor model independent analysis of the inverse beta decay prompt energy spectrum as a function of baseline constrains significant portions of the previously allowed sterile neutrino oscillation parameter space at 95% confidence level and disfavors the best fit of the reactor antineutrino anomaly at 2.2σ confidence level.