105 research outputs found

    Neurofilament Heavy Polypeptide Regulates the Akt-β-Catenin Pathway in Human Esophageal Squamous Cell Carcinoma

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    Aerobic glycolysis and mitochondrial dysfunction are common features of aggressive cancer growth. We observed promoter methylation and loss of expression in neurofilament heavy polypeptide (NEFH) in a significant proportion of primary esophageal squamous cell carcinoma (ESCC) samples that were of a high tumor grade and advanced stage. RNA interference-mediated knockdown of NEFH accelerated ESCC cell growth in culture and increased tumorigenicity in vivo, whereas forced expression of NEFH significantly inhibited cell growth and colony formation. Loss of NEFH caused up-regulation of pyruvate kinase-M2 type and down-regulation of pyruvate dehydrogenase, via activation of the Akt/β-catenin pathway, resulting in enhanced aerobic glycolysis and mitochondrial dysfunction. The acceleration of glycolysis and mitochondrial dysfunction in NEFH-knockdown cells was suppressed in the absence of β-catenin expression, and was decreased by the treatment of 2-Deoxyglucose, a glycolytic inhibitor, or API-2, an Akt inhibitor. Loss of NEFH activates the Akt/β-catenin pathway and increases glycolysis and mitochondrial dysfunction. Cancer cells with methylated NEFH can be targeted for destruction with specific inhibitors of deregulated downstream pathways

    SEGUE-2 Limits on Metal-Rich Old-Population Hypervelocity Stars In the Galactic Halo

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    We present new limits on the ejection of metal-rich old-population hypervelocity stars from the Galactic center (GC) as probed by the SEGUE-2 survey. Our limits are a factor of 3-10 more stringent than previously reported, depending on stellar type. Compared to the known population of B-star ejectees, there can be no more than 30 times more metal-rich old-population F/G stars ejected from the GC. Because B stars comprise a tiny fraction of a normal stellar population, this places significant limits on a combination of the GC mass function and the ejection mechanism for hypervelocity stars. In the presence of a normal GC mass function, our results require an ejection mechanism that is about 5.5 times more efficient at ejecting B-stars compared to low-mass F/G stars.Comment: 18 pages including 5 figures; Submitted to Ap

    Old-Population Hypervelocity Stars from the Galactic Center: Limits from the SDSS

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    We present limits on the ejection of old-population HVS from a sample of over 290,000 stars selected from the SDSS. We derive the speed at the solar circle from the measured positions and radial velocities by assuming a radial orbit and adopting a simple isothermal model of the Galactic halo, which enables us to identify candidate bound and unbound ejectees. We find 4 candidate bound F-stars from this sample, all with negative Galactocentric radial velocity (i.e., returning toward the GC). We additionally find 2 candidate unbound stars (one F and one G), however, existing proper motion measurements make these unlikely to be emerging from the GC. These data place an upper limit on the rate of ejection of old-population stars from the GC of ~45/Myr. Comparing to the rate for more massive B-star ejectees of ~0.5/Myr, our limit on the rate of ejection of old-population HVS shows that the mass function at the GC is not bottom-heavy and is consistent with being normal. Future targeted surveys of old-population HVS could determine if it is indeed top-heavy.Comment: Submitted to ApJ; 14 pages including 2 figure

    ssDNA-binding protein 2 is frequently hypermethylated and suppresses cell growth in human prostate cancer

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    Purpose: Prostate cancer is a major cause of cancer death among men and the development of new biomarkers is important to augment current detection approaches. Experimental Design: We identified hypermethylation of the ssDNA-binding protein 2 (SSBP2) promoter as a potential DNA marker for human prostate cancer based on previous bioinformatics results and pharmacologic unmasking microarray. We then did quantitative methylation-specific PCR in primary prostate cancer tissues to confirm hypermethylation of the SSBP2 promoter, and analyzed its correlation with clinicopathologic data. We further examined SSBP2 expression in primary prostate cancer and studied its role in cell growth. Results: Quantitative methylation-specific PCR results showed that the SSBP2 promoter was hypermethylated in 54 of 88 (61.4%) primary prostate cancers versus 0 of 23 (0%) in benign prostatic hyperplasia using a cutoff value of 120. Furthermore, we found that expression of SSBP2 was down-regulated in primary prostate cancers and cancer cell lines. Hypermethylation of the SSBP2 promoter and its expression were closely associated with higher stages of prostate cancer. Reactivation of SSBP2 expression by the demethylating agent 5-aza-2'-deoxycytidine in prostate cancer cell lines confirmed epigenetic inactivation as one major mechanism of SSBP2 regulation. Moreover, forced expression of SSBP2 inhibited prostate cancer cell proliferation in the colony formation assay and caused cell cycle arrest. Conclusion: SSBP2 inhibits prostate cancer cell proliferation and seems to represent a novel prostate cancer - specific DNA marker, especially in high stages of human prostate cancer

    TOI-150: A transiting hot Jupiter in the TESS southern CVZ

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    We report the detection of a hot Jupiter ($M_{p}=1.75_{-0.17}^{+0.14}\ M_{J},, R_{p}=1.38\pm0.04\ R_{J})orbitingamiddleagedstar() orbiting a middle-aged star (\log g=4.152^{+0.030}_{-0.043})intheTransitingExoplanetSurveySatellite(TESS)southerncontinuousviewingzone() in the Transiting Exoplanet Survey Satellite (TESS) southern continuous viewing zone (\beta=-79.59^{\circ}$). We confirm the planetary nature of the candidate TOI-150.01 using radial velocity observations from the APOGEE-2 South spectrograph and the Carnegie Planet Finder Spectrograph, ground-based photometric observations from the robotic Three-hundred MilliMeter Telescope at Las Campanas Observatory, and Gaia distance estimates. Large-scale spectroscopic surveys, such as APOGEE/APOGEE-2, now have sufficient radial velocity precision to directly confirm the signature of giant exoplanets, making such data sets valuable tools in the TESS era. Continual monitoring of TOI-150 by TESS can reveal additional planets and subsequent observations can provide insights into planetary system architectures involving a hot Jupiter around a star about halfway through its main-sequence life.Comment: 13 pages, 3 figures, 2 tables, accepted to ApJ

    Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

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    We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of Δχ24630\Delta\chi^2\sim 4630, but the interpretation of the signal suffers from two types of degeneracies. One type is caused by the previously known close/wide degeneracy, and the other is caused by an ambiguity between two solutions, in which one solution requires to incorporate finite-source effects, while the other solution is consistent with a point-source interpretation. Although difficult to be firmly resolved based on only the photometric data, the degeneracy is resolved in strong favor of the point-source solution with the additional external information obtained from astrometric and spectroscopic observations. The small astrometric offset between the source and baseline object supports that the blend is the lens and this interpretation is further secured by the consistency of the spectroscopic distance estimate of the blend with the lensing parameters of the point-source solution. The estimated mass of the host is 1.0±0.1 M1.0\pm 0.1~M_\odot and the mass of the planet is 4.5±0.6 MJ4.5\pm 0.6~M_{\rm J} (close solution) or 4.8±0.6 MJ4.8\pm 0.6~M_{\rm J} (wide solution) and the lens is located at a distance of 3.2±0.53.2\pm 0.5~kpc. The bright nature of the lens, with I17.1I\sim 17.1 (V18.2V\sim 18.2), combined with its dominance of the observed flux suggest that radial-velocity (RV) follow-up observations of the lens can be done using high-resolution spectrometers mounted on large telescopes, e.g., VLT/ESPRESSO, and this can potentially not only measure the period and eccentricity of the planet but also probe for close-in planets. We estimate that the expected RV amplitude would be 60sini m s1\sim 60\sin i ~{\rm m~s}^{-1}.Comment: 12 pages, 11 figures, 4 table

    Human AQP5 Plays a Role in the Progression of Chronic Myelogenous Leukemia (CML)

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    Aquaporins (AQPs) have previously been associated with increased expression in solid tumors. However, its expression in hematologic malignancies including CML has not been described yet. Here, we report the expression of AQP5 in CML cells by RT-PCR and immunohistochemistry. While normal bone marrow biopsy samples (n = 5) showed no expression of AQP5, 32% of CML patient samples (n = 41) demonstrated AQP5 expression. In addition, AQP5 expression level increased with the emergence of imatinib mesylate resistance in paired samples (p = 0.047). We have found that the overexpression of AQP5 in K562 cells resulted in increased cell proliferation. In addition, small interfering RNA (siRNA) targeting AQP5 reduced the cell proliferation rate in both K562 and LAMA84 CML cells. Moreover, by immunoblotting and flow cytometry, we show that phosphorylation of BCR-ABL1 is increased in AQP5-overexpressing CML cells and decreased in AQP5 siRNA-treated CML cells. Interestingly, caspase9 activity increased in AQP5 siRNA-treated cells. Finally, FISH showed no evidence of AQP5 gene amplification in CML from bone marrow. In summary, we report for the first time that AQP5 is overexpressed in CML cells and plays a role in promoting cell proliferation and inhibiting apoptosis. Furthermore, our findings may provide the basis for a novel CML therapy targeting AQP5
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