The identification and validation of a targeted therapy for patients with triple‐negative breast cancer (TNBC) is currently one of the most urgent needs in breast cancer therapeutics. One of the key ...reasons for the failure to develop a new therapy for this subgroup of breast cancer patients has been the difficulty in identifying a highly prevalent, targetable molecular alteration in these tumors. Recently however, the p53 gene was found to be mutated in approximately 80% of basal/TNBC, raising the possibility that targeting the mutant p53 protein product might be a new approach for the treatment of this form of breast cancer. In this study, we investigated the anti‐cancer activity of PRIMA‐1 and PRIMA‐1MET (APR‐246), two compounds which were previously reported to reactivate mutant p53 and convert it to a form with wild‐type (WT) properties. Using a panel of 18 breast cancer cell lines and 2 immortalized breast cell lines, inhibition of proliferation by PRIMA‐1 and PRIMA‐1MET was found to be cell‐line dependent, but independent of cell line molecular subtype. Although response was independent of molecular subtype, p53 mutated cell lines were significantly more sensitive to PRIMA‐1MET than p53 WT cells (p = 0.029). Furthermore, response (measured as IC50 value) correlated significantly with p53 protein level as measured by ELISA (p = 0.0089, r=−0.57, n = 19). In addition to inhibiting cell proliferation, PRIMA‐1MET induced apoptosis and inhibited migration in a p53 mutant‐dependent manner. Based on our data, we conclude that targeting mutant p53 with PRIMA‐1MET is a potential new approach for treating p53‐mutated breast cancer, including the subgroup with triple‐negative (TN) disease.
What's new?
There is an urgent need for new therapies that specifically target triple‐negative breast cancer (TNBC). Surprisingly, about 80% of basal/TNBCs have recently been found to carry mutations in the p53 gene. A number of novel compounds can restore normal p53 activity. In this study, the authors found that one of these compounds, called PRIMA‐1MET, can inhibit proliferation and migration, and induce apoptosis, in TNBC cells in vitro. These results suggest that PRIMA‐1MET might offer a potential new therapeutic approach for treating p53‐mutated breast cancers, including TNBCs.
We present microphysical observations of cumulus clouds measured over the southwest peninsula of the UK during the COnvective Precipitation Experiment (COPE) in August 2013, which are framed into a ...wider context using ground-based and airborne radar measurements. Two lines of cumulus clouds formed in the early afternoon along convergence lines aligned with the peninsula. The lines became longer and broader during the afternoon due to new cell formation and stratiform regions forming downwind of the convective cells. Ice concentrations up to 350 L−1, well in excess of the expected ice nuclei (IN) concentrations, were measured in the mature stratiform regions, suggesting that secondary ice production was active. Detailed sampling focused on an isolated liquid cloud that glaciated as it matured to merge with a band of cloud downwind. In the initial cell, drizzle concentrations increased from ∼ 0.5 to ∼ 20 L−1 in around 20 min. Ice concentrations developed up to a few per litre, which is around the level expected of primary IN. The ice images were most consistent with freezing drizzle, rather than smaller cloud drops or interstitial IN forming the first ice. As new cells emerged in and around the cloud, ice concentrations up to 2 orders of magnitude higher than the predicted IN concentrations developed, and the cloud glaciated over a period of 12–15 min. Almost all of the first ice particles to be observed were frozen drops, while vapour-grown ice crystals were dominant in the latter stages. Our observations are consistent with the production of large numbers of small secondary ice crystals/fragments, by a mechanism such as Hallett–Mossop or droplets shattering upon freezing. Some of the small ice froze drizzle drops on contact, while others grew more slowly by vapour deposition. Graupel and columns were seen in cloud penetrations up to the −12 °C level, though many ice particles were mixed habit due to riming and growth by vapour deposition at multiple temperatures. Our observations demonstrate that the freezing of drizzle/raindrops is an important process that dominates the formation of large ice in the intermediate stages of cloud development. As these frozen drops were the first precipitation observed, interactions between the warm-rain and secondary ice production processes appear to be key to determining the timing and location of precipitation.
Total bacteria, fungal spore and yeast counts were compared with ultraviolet-light-induced fluorescence (UV-LIF) measurements of ambient aerosol at the summit of the Puy de Dôme (PdD) mountain in ...central France (1465 m a.s.l), which represents a background elevated site. Bacteria, fungal spores and yeast were enumerated by epifluorescence microscopy (EFM) and found to number 2.2 to 23 L−1 and 0.8 to 2 L−1, respectively. Bacteria counts on two successive nights were an order of magnitude larger than in the intervening day. A wide issue bioaerosol spectrometer, version 3 (WIBS-3) was used to perform UV-LIF measurements on ambient aerosol sized 0.8 to 20 μm. Mean total number concentration was 270 L−1 (σ = 66 L−1), found predominantly in a size mode at 2 μm for most of the campaign. Total concentration (fluorescent + non-fluorescent aerosol) peaked at 500 L−1 with a size mode at 1 μm because of a change in air mass origin lasting around 48 h. The WIBS-3 features two excitation and fluorescence detection wavelengths corresponding to different biological molecules, although non-biological interferents also contribute. The mean fluorescent particle concentration after short-wave (280 nm; associated with tryptophan) excitation was 12 L−1 (σ = 6 L−1), and did not vary much throughout the campaign. In contrast, the mean concentration of particles fluorescent after long-wave (370 nm; associated with NADH) excitation was 95 L−1 (σ = 25 L−1), and a nightly rise and subsequent fall of up to 100 L−1 formed a strong diurnal cycle in the latter. The two fluorescent populations exhibited size modes at 3 μm and 2 to 3 μm, respectively. A hierarchical agglomerative cluster analysis algorithm was applied to the data and used to extract different particle factors. A cluster concentration time series representative of bacteria was identified. This was found to exhibit a diurnal cycle with a maximum peak appearing during the day. Analysis of organic mass spectra recorded using an aerosol mass spectrometer (AMS; Aerodyne Inc.) suggests that aerosol reaching the site at night was more aged than that during the day, indicative of sampling the residual layer at night. Supplementary meteorological data and previous work also show that PdD lies in the residual layer/free troposphere at night, and this is thought to cause the observed diurnal cycles in organic-type and fluorescent aerosol particles. Based on the observed disparity between bacteria and fluorescent particle concentrations, fluorescent non-PBA is likely to be important in the WIBS-3 data and the surprisingly high fluorescent concentration in the residual layer/free troposphere raises questions about a ubiquitous background in continental air during the summer.
Black carbon aerosols (BC) at a London urban site were characterised in both winter- and summertime 2012 during the Clean Air for London (ClearfLo) project. Positive matrix factorisation (PMF) ...factors of organic aerosol mass spectra measured by a high-resolution aerosol mass spectrometer (HR-AMS) showed traffic-dominant sources in summer but in winter the influence of additional non-traffic sources became more important, mainly from solid fuel sources (SF). Measurements using a single particle soot photometer (SP2, DMT), showed the traffic-dominant BC exhibited an almost uniform BC core size (Dc) distribution with very thin coating thickness throughout the detectable range of Dc. However, the size distribution of Dc (project average mass median Dc = 149 ± 22 nm in winter, and 120 ± 6 nm in summer) and BC coating thickness varied significantly in winter. A novel methodology was developed to attribute the BC number concentrations and mass abundances from traffic (BCtr) and from SF (BCsf), by using a 2-D histogram of the particle optical properties as a function of BC core size, as measured by the SP2. The BCtr and BCsf showed distinctly different Dc distributions and coating thicknesses, with BCsf displaying larger Dc and larger coating thickness compared to BCtr. BC particles from different sources were also apportioned by applying a multiple linear regression between the total BC mass and each AMS-PMF factor (BC–AMS–PMF method), and also attributed by applying the absorption spectral dependence of carbonaceous aerosols to 7-wavelength Aethalometer measurements (Aethalometer method). Air masses that originated from westerly (W), southeasterly (SE), and easterly (E) sectors showed BCsf fractions that ranged from low to high, and whose mass median Dc values were 137 ± 10 nm, 143 ± 11 nm and 169 ± 29 nm, respectively. The corresponding bulk relative coating thickness of BC (coated particle size/BC core – Dp/Dc) for these same sectors was 1.28 ± 0.07, 1.45 ± 0.16 and 1.65 ± 0.19. For W, SE and E air masses, the number fraction of BCsf ranged from 6 ± 2% to 11 ± 5% to 18 ± 10%, respectively, but importantly the larger BC core sizes lead to an increased fraction of BCsf in terms of mass than number (for W, SE and E air masses, the BCsf mass fractions ranged from 16 ± 6%, 24 ± 10% and 39 ± 14%, respectively). An increased fraction of non-BC particles (particles that did not contain a BC core) was also observed when SF sources were more significant. The BC mass attribution by the SP2 method agreed well with the BC–AMS–PMF multiple linear regression method (BC–AMS–PMF : SP2 ratio = 1.05, r2 = 0.80) over the entire experimental period. Good agreement was found between BCsf attributed with the Aethalometer model and the SP2. However, the assumed absorption Ångström exponent (αwb) had to be changed according to the different air mass sectors to yield the best comparison with the SP2. This could be due to influences of fuel type or burn phase.
Black carbon aerosol (BC) deposited to the Arctic sea ice or present in the free troposphere can significantly affect the Earth's radiation budget at high latitudes yet the BC burden in these regions ...and the regional source contributions are poorly constrained. Aircraft measurements of aerosol composition in the European Arctic were conducted during the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Pollutant plumes were encountered throughout the lower to upper Arctic troposphere featuring enhancements in CO and aerosol mass loadings, which were chemically speciated into BC and non-refractory sulphate and organic matter. FLEXPART-WRF simulations have been performed to evaluate the likely contribution to the pollutants from regional ground sources. By combining up-to-date anthropogenic and open fire biomass burning (OBB) inventories, we have been able to compare the contributions made to the observed pollution layers from the sources of eastern/northern Asia (AS), Europe (EU) and North America (NA). Over 90 % of the contribution to the BC was shown to arise from non-OBB anthropogenic sources. AS sources were found to be the major contributor to the BC burden, increasing background BC loadings by a factor of 3–5 to 100.8 ± 48.4 ng sm−3 (in standard air m3 at 273.15 K and 1013.25 mbar) and 55.8 ± 22.4 ng sm−3 in the middle and upper troposphere respectively. AS plumes close to the tropopause (about 7.5–8 km) were also observed, with BC concentrations ranging from 55 to 73 ng sm−3, which will potentially have a significant radiative impact. EU sources influenced the middle troposphere with a BC mean concentration of 70.8 ± 39.1 ng sm−3 but made a minor contribution to the upper troposphere due to the relatively high latitude of the source region. The contribution of NA was shown to be much lower at all altitudes with BC mean concentration of 20 ng sm−3. The BC transported to the Arctic is mixed with a non-BC volume fraction representing between 90–95 % of the mass, and has a relatively uniform core size distribution with mass median diameter 190–210 nm and geometric standard deviation σg = 1.55–1.65 and this varied little across all source regions. It is estimated that 60–95 % of BC is scavenged between emission and receptor based on BC / ΔCO comparisons between source inventories and measurement. We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to BC across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase.
During the winter of 2013 and 2014 measurements of cloud microphysical properties over a 5-week period at the high-alpine site Jungfraujoch, Switzerland, were carried out as part of the Cloud Aerosol ...Characterisation Experiments (CLACE) and the Ice Nucleation Process Investigation and Quantification project (INUPIAQ). Measurements of aerosol properties at a second, lower site, Schilthorn, Switzerland, were used as input for a primary ice nucleation scheme to predict ice nuclei concentrations at Jungfraujoch. Frequent, rapid transitions in the ice and liquid properties of the clouds at Jungfraujoch were identified that led to large fluctuations in ice mass fractions over temporal scales of seconds to hours. During the measurement period we observed high concentrations of ice particles that exceeded 1000 L−1 at temperatures around −15 °C, verified by multiple instruments. These concentrations could not be explained using the usual primary ice nucleation schemes, which predicted ice nucleus concentrations several orders of magnitude smaller than the peak ice crystal number concentrations. Secondary ice production through the Hallett–Mossop process as a possible explanation was ruled out, as the cloud was rarely within the active temperature range for this process. It is shown that other mechanisms of secondary ice particle production cannot explain the highest ice particle concentrations. We describe four possible mechanisms that could lead to high cloud ice concentrations generated from the snow-covered surfaces surrounding the measurement site. Of these we show that hoar frost crystals generated at the cloud enveloped snow surface could be the most important source of cloud ice concentrations. Blowing snow was also observed to make significant contributions at higher wind speeds when ice crystal concentrations were < 100 L−1.
Adult Mesenchymal Stem Cells (MSCs) have a well-established tumor-homing capacity, highlighting potential as tumor-targeted delivery vehicles. MSCs secrete extracellular vesicle (EV)-encapsulated ...microRNAs, which play a role in intercellular communication. The aim of this study was to characterize a potential tumor suppressor microRNA, miR-379, and engineer MSCs to secrete EVs enriched with miR-379 for in vivo therapy of breast cancer. miR-379 expression was significantly reduced in lymph node metastases compared to primary tumor tissue from the same patients. A significant reduction in the rate of tumor formation and growth in vivo was observed in T47D breast cancer cells stably expressing miR-379. In more aggressive HER2-amplified HCC-1954 cells, HCC-379 and HCC-NTC tumor growth rate in vivo was similar, but increased tumor necrosis was observed in HCC-379 tumors. In response to elevated miR-379, COX-2 mRNA and protein was also significantly reduced in vitro and in vivo. MSCs were successfully engineered to secrete EVs enriched with miR-379, with the majority found to be of the appropriate size and morphology of exosomal EVs. Administration of MSC-379 or MSC-NTC cells, or EVs derived from either cell population, resulted in no adverse effects in vivo. While MSC-379 cells did not impact tumor growth, systemic administration of cell-free EVs enriched with miR-379 was demonstrated to have a therapeutic effect. The data presented support miR-379 as a potent tumor suppressor in breast cancer, mediated in part through regulation of COX-2. Exploiting the tumor-homing capacity of MSCs while engineering the cells to secrete EVs enriched with miR-379 holds exciting potential as an innovative therapy for metastatic breast cancer.
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