Targeted Pten deletion plus p53-R270H mutation in mouse mammary epithelium induces aggressive claudin-low and basal-like breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC), an aggressive disease comprising several subtypes including basal-like and claudin-low, involves frequent deletions or point mutations in TP53, as well as loss of PTEN. We previously showed that combined deletion of both tumor suppressors in the mouse mammary epithelium invariably induced claudin-low-like TNBC. The effect of p53 mutation plus Pten deletion on mammary tumorigenesis and whether this combination can induce basal-like TNBC in the mouse are unknown.

METHODS

WAP-Cre:Pten(f/f):p53(lox.stop.lox_R270H) composite mice were generated in which Pten is deleted and a p53-R270H mutation in the DNA-binding domain is induced upon expression of Cre-recombinase in pregnancy-identified alveolar progenitors. Tumors were characterized by histology, marker analysis, transcriptional profiling [GEO-GSE75989], bioinformatics, high-throughput (HTP) FDA drug screen as well as orthotopic injection to quantify tumor-initiating cells (TICs) and tail vein injection to identify lung metastasis.

RESULTS

Combined Pten deletion plus induction of p53-R270H mutation accelerated formation of four distinct mammary tumors including poorly differentiated adenocarcinoma (PDA) and spindle/mesenchymal-like lesions. Transplantation assays revealed highest frequency of TICs in PDA and spindle tumors compared with other subtypes. Hierarchical clustering demonstrated that the PDA and spindle tumors grouped closely with human as well as mouse models of basal and claudin-low subtypes, respectively. HTP screens of primary Pten(∆):p53(∆) vs. Pten(∆):p53(R270H) spindle tumor cells with 1120 FDA-approved drugs identified 8-azaguanine as most potent for both tumor types, but found no allele-specific inhibitor. A gene set enrichment analysis revealed increased expression of a metastasis pathway in Pten(∆):p53(R270H) vs. Pten(∆):p53(∆) spindle tumors. Accordingly, following tail vein injection, both Pten(∆):p53(R270H) spindle and PDA tumor cells induced lung metastases and morbidity significantly faster than Pten(∆):p53(∆) double-deletion cells, and this was associated with the ability of Pten(∆):p53(R270H) tumor cells to upregulate E-cadherin expression in lung metastases.

CONCLUSIONS

Our results demonstrate that WAP-Cre:Pten(f/f):p53(lox.stop.lox_R270H) mice represent a tractable model to study basal-like breast cancer because unlike p53 deletion, p53(R270H) mutation in the mouse does not skew tumors toward the claudin-low subtype. The WAP-Cre:Pten(f/f):p53(lox.stop.lox_R270H) mice develop basal-like breast cancer that is enriched in TICs, can readily form lung metastasis, and provides a preclinical model to study both basal-like and claudin-low TNBC in immune-competent mice.

Fractionation and release behaviors of metals (In, Mo, Sr) from industrial sludge

Little is known on the fate of rare metals in the environment and the associated risks. The fractionation and release of three metals of an industrial sludge were assessed. The average concentration ranges from 39.3 to 41.5 mg/kg for indium (In), 43.1-77.8 mg/kg for molybdenum (Mo), and 131.1-376.4 mg/kg for strontium (Sr). Sequential extraction results implied that In was mobile, while Mo and Sr were immobile. However, experimental results from effects of Eh/pH revealed that In was slightly mobile under acidic (pH 4.5) in Eh range of 210-260 mV, and immobile under alkaline conditions (9.0) in Eh range of -250 to 125 mV. The release of Mo was slightly mobile under acidic conditions. However, Mo was very mobile under alkaline conditions and it increased with decreasing Eh. The release of Sr was significant under acidic conditions; however, it was immobile under alkaline conditions. Solubility and adsorption as affected by pH, and speciation could explain their release behaviors. Discrepancy in predictions from sequential extraction and actual observation from Eh/pH experiments was discussed.

Ras Signaling Is a Key Determinant for Metastatic Dissemination and Poor Survival of Luminal Breast Cancer Patients

Breast cancer is associated with alterations in a number of growth factor and hormone-regulated signaling pathways. Mouse models of metastatic breast cancer typically feature mutated oncoproteins that activate PI3K, Stat3, and Ras signaling, but the individual and combined roles of these pathways in breast cancer progression are poorly understood. In this study, we examined the relationship between oncogenic pathway activation and breast cancer subtype by analyzing mouse mammary tumor formation in which each pathway was activated singly or pairwise. All three oncogenes showed cooperation during primary tumor formation, but efficient dissemination was only dependent on Ras. In addition, transcriptional profiling demonstrated that Ras induced adenocarcinomas with molecular characteristics related to human basal-like and HER2(+) tumors. In contrast, Ras combined with PIK3CA(H1047R), an oncogenic mutant linked to ERα(+)/luminal breast cancer in humans, induced metastatic luminal B-like tumors. Consistent with these data, elevated Ras signaling was associated with basal-like and HER2(+) subtype tumors in humans and showed a statistically significant negative association with estrogen receptor (ER) signaling across all breast cancer. Despite this, there are luminal tumors with elevated Ras signaling. Importantly, when considered as a continuous variable, Ras pathway activation was strongly linked to reduced survival of patients with ERα(+) disease independent of PI3K or Stat3 activation. Therefore, our studies suggest that Ras activation is a key determinant for dissemination and poor prognosis of ERα(+)/luminal breast cancer in humans, and hormone therapy supplemented with Ras-targeting agents may be beneficial for treating this aggressive subtype.

New measurement of antineutrino oscillation with the full detector configuration at Daya Bay

We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th}  ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3}  eV^{2} in the three-neutrino framework.

Reduction of concentrated nitrate by using in situ synthesized zero-valent copper

Although zero-valent iron represents a promising approach for reduction of nitrate (NO(3)(-)) in water, its application in concentrated nitrate is limited by surface passivation. In this study, an alternative approach using in situ synthesized zero-valent copper (Cu(0)) produced by borohydride (NaBH(4)) was investigated. Complete reduction was observed within 55 min by reacting 677 mg-N/L of NO(3)(-) with CuO (0.312 g/L) and NaBH(4) (4.16 g/L) at 60 °C. The pseudo-first-order rate constant was 0.059 min(-1), and it increased threefold when the CuO dose was increased to 1.24 g/L. Increasing the NaBH(4) dose produced less nitrite (NO(2)(-)) throughout the experiments, indicating that it is the primary agent for reducing NO(2)(-). The initial pH exerted a significant effect on the reaction rate, and NO(3)(-) was rapidly reduced when the initial pH was less than 4. Based on the research findings, possible reaction pathways for NO(3)(-) reduction by Cu(0) are proposed in this work.

Combined deletion of Pten and p53 in mammary epithelium accelerates triple-negative breast cancer with dependency on eEF2K

The tumor suppressors Pten and p53 are frequently lost in breast cancer, yet the consequences of their combined inactivation are poorly understood. Here, we show that mammary-specific deletion of Pten via WAP-Cre, which targets alveolar progenitors, induced tumors with shortened latency compared to those induced by MMTV-Cre, which targets basal/luminal progenitors. Combined Pten-p53 mutations accelerated formation of claudin-low, triple-negative-like breast cancer (TNBC) that exhibited hyper-activated AKT signaling and more mesenchymal features relative to Pten or p53 single-mutant tumors. Twenty-four genes that were significantly and differentially expressed between WAP-Cre:Pten/p53 and MMTV-Cre:Pten/p53 tumors predicted poor survival for claudin-low patients. Kinome screens identified eukaryotic elongation factor-2 kinase (eEF2K) inhibitors as more potent than PI3K/AKT/mTOR inhibitors on both mouse and human Pten/p53-deficient TNBC cells. Sensitivity to eEF2K inhibition correlated with AKT pathway activity. eEF2K monotherapy suppressed growth of Pten/p53-deficient TNBC xenografts in vivo and cooperated with doxorubicin to efficiently kill tumor cells in vitro. Our results identify a prognostic signature for claudin-low patients and provide a rationale for using eEF2K inhibitors for treatment of TNBC with elevated AKT signaling.

Search for a light sterile neutrino at Daya Bay

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.

Microalgae harvesting by flotation using natural saponin and chitosan

This study aims to investigate the harvesting of microalgae by dispersed air flotation (DiAF) using natural biosurfactant saponin as the collector and chitosan as the flocculant. Two types of microalgae, Chlorella vulgaris and Scenedesmus obliquus, were used in this study. It was observed that saponin was a good frother, but not an effective collector when used alone for flotation separation of algae. However, with the pre-flocculation of 5 mg/L of chitosan, separation efficiency of >93% microalgae cells was found at 20 mg/L of saponin. Removal efficiency of >54.4% and >73.0% was found for polysaccharide and protein, respectively at 20 mg/L of saponin and chitosan each. Experimental results show that DiAF using saponin and chitosan is effective for separation of microalgae, and algogenic organic matter (AOM). It can potentially be applied in the integrated microalgae-based biorefinery.

A Tumor initiating cell-enriched prognostic signature for HER2+:ERα- breast cancer; rationale, new features, controversies and future directions

The high intra- and inter-tumor heterogeneity of many types of cancers, including breast cancer (BC), poses great challenge to development of subtype-specific prognosis. In BC, the classification of tumors as either ERα⁺ (Luminal A and Luminal B), HER2⁺ (ERα⁺ or ERα⁻) or triple-negative (TNBC)(Basal-like, claudin-low) guides both prognostication and therapy. Indeed, prognostic signatures for ERα⁺ BC are being incorporated into clinical use. However, these signatures distinguish between luminal A (low risk) and Luminal B (high risk) BC; signatures that identify low/high risk patients with luminal B BC are yet to be developed. Likewise, no signature is in clinical use for HER2⁺ or TNBC. The major obstacles to development of robust signatures stem from diversity of BC, clonal evolution and heterogeneity within each subtype. We have recently generated a prognostic signature for HER2⁺:ERα⁻ BC based on the identification of genes that were differentially expressed in a tumor-initiating cell (TIC)-enriched fraction versus non-TIC fraction from a mouse model of HER2⁺ BC (MMTV-Hers/Neu). Here we describe the rationale behind development of this prognosticator, and present new features of the signature, including elevated PI3K pathway activity and low TNFalpha and IFNgamma signaling in high-risk tumors. In addition, we address controversies in the field such as whether random gene expression signatures significantly associate with cancer outcome. Finally, we suggest a guideline for development of prognostic signatures and discuss future directions.

Mesenteric lymph reperfusion exacerbates spleen injury caused by superior mesenteric artery occlusion shock

The intestinal lymph pathway plays an important role in the pathogenesis of organ injury following superior mesenteric artery occlusion (SMAO) shock. We hypothesized that mesenteric lymph reperfusion (MLR) is a major cause of spleen injury after SMAO shock. To test this hypothesis, SMAO shock was induced in Wistar rats by clamping the superior mesenteric artery (SMA) for 1 h, followed by reperfusion for 2 h. Similarly, MLR was performed by clamping the mesenteric lymph duct (MLD) for 1 h, followed by reperfusion for 2 h. In the MLR+SMAO group rats, both the SMA and MLD were clamped and then released for reperfusion for 2 h. SMAO shock alone elicited: 1) splenic structure injury, 2) increased levels of malondialdehyde, nitric oxide (NO), intercellular adhesion molecule-1, endotoxin, lipopolysaccharide receptor (CD14), lipopolysaccharide-binding protein, and tumor necrosis factor-α, 3) enhanced activities of NO synthase and myeloperoxidase, and 4) decreased activities of superoxide dismutase and ATPase. MLR following SMAO shock further aggravated these deleterious effects. We conclude that MLR exacerbates spleen injury caused by SMAO shock, which itself is associated with oxidative stress, excessive release of NO, recruitment of polymorphonuclear neutrophils, endotoxin translocation, and enhanced inflammatory responses.

Targeting HER2(+) breast cancer: the TBK1/IKKε axis

HER2⁺ breast cancer (BC) is a highly aggressive subtype, affecting ~20% of BC patients. Current treatments include adjuvant or neoadjuvant chemotherapy plus anti-HER2 agents such as trastuzumab, a monoclonal antibody directed against HER2. Despite improvement in disease free survival, most patients eventually succumb to metastatic disease, which is largely incurable. Consequently, there is an urgent need to identify novel drugs that can efficiently kill HER2⁺ BC and/or potentiate the effect of existing anti-HER2 therapies. We performed a lenti-viral shRNA kinome screen on non-adherent mouse Her2/Neu tumorspheres and identified TBK1, a non-canonical IκB kinase (IKK), as the most potent target [1]. TBK1 knock-down, or treatment with TBK1-II, a drug that efficiently inhibits TBK1 and its close relative IKKε (IKBKE), suppressed growth of human HER2⁺ BC cells and induced cellular senescence. Senescence was associated with inhibition of phosphorylated/active p65-NFkB and induction of the cell cycle inhibitor, p16^ink4a. In addition, TBK1-II cooperated with lapatinib, a EGFR/HER2 inhibitor, to accelerate apoptosis in vitro and suppress tumor growth in a xenograft model of HER2⁺ BC. Thus, TBK1/IKKε inhibitors may improve treatment of HER2⁺ BC in cooperation with anti-HER2 therapy.

Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

shRNA kinome screen identifies TBK1 as a therapeutic target for HER2+ breast cancer

HER2(+) breast cancer is currently treated with chemotherapy plus anti-HER2 inhibitors. Many patients do not respond or relapse with aggressive metastatic disease. Therefore, there is an urgent need for new therapeutics that can target HER2(+) breast cancer and potentiate the effect of anti-HER2 inhibitors, in particular those that can target tumor-initiating cells (TIC). Here, we show that MMTV-Her2/Neu mammary tumor cells cultured as nonadherent spheres or as adherent monolayer cells select for stabilizing mutations in p53 that "immortalize" the cultures and that, after serial passages, sphere conditions maintain TICs, whereas monolayer cells gradually lose these tumorigenic cells. Using tumorsphere formation as surrogate for TICs, we screened p53-mutant Her2/Neu(+) tumorsphere versus monolayer cells with a lentivirus short hairpin RNA kinome library. We identified kinases such as the mitogen-activated protein kinase and the TGFβR protein family, previously implicated in HER2(+) breast cancer, as well as autophagy factor ATG1/ULK1 and the noncanonical IκB kinase (IKK), TANK-binding kinase 1 (TBK1), which have not been previously linked to HER2(+) breast cancer. Knockdown of TBK1 or pharmacologic inhibition of TBK1 and the related protein, IKKε, suppressed growth of both mouse and human HER2(+) breast cancer cells. TBK1/IKKε inhibition promoted cellular senescence by suppressing p65-NF-κB and inducing p16(Ink4a). In addition, TBK1/IKKε inhibition cooperated with lapatinib, a HER2/EGFR1-targeted drug, to accelerate apoptosis and kill HER2(+) breast cancer cells both in culture and in xenografts. Our results suggest that patients with HER2(+) breast cancer may benefit from anti-TBK1/IKKε plus anti-HER2 combination therapies and establish conditions that can be used to screen for additional TIC-specific inhibitors of HER2(+) breast cancer.

Enhanced adsorption of quaternary amine using modified activated carbon

This study examined different methodologies to modify activated carbon (AC) for the removal of quaternary amine, tetramethylammonium hydroxide (TMAH), from water. Commercial carbon (WAC) was treated by nitric acid oxidation (NA-WAC), silica impregnation (SM-WAC0.5), and oxygen plasma (P10-WAC), and their characteristics and adsorption capacity were compared. The Langmuir model fitted the equilibrium adsorption data well under different pH. The maximum adsorption capacity of WAC was 27.77 mg/g, while those of NA-WAC, SM-WAC 0.5, and P10-WAC were 37.46, 32.83 and 29.03 mg/g, respectively. Nitric acid oxidation was the most effective method for enhancing the adsorption capacity of TMAH. Higher pH was favorable for TMAH adsorption. Desorption study revealed that NA-WAC had no considerable reduction in performance even after five cycles of regeneration by 0.1 N hydrochloric acid. It was proposed that electrostatic interaction was the main mechanism of TMAH adsorption on activated carbon.

RB1 status in triple negative breast cancer cells dictates response to radiation treatment and selective therapeutic drugs

Triple negative breast cancer (TNBC) includes basal-like and claudin-low subtypes for which only chemotherapy and radiation therapy are currently available. The retinoblastoma (RB1) tumor suppressor is frequently lost in human TNBC. Knockdown of RB1 in luminal BC cells was shown to affect response to endocrine, radiation and several antineoplastic drugs. However, the effect of RB1 status on radiation and chemo-sensitivity in TNBC cells and whether RB1 status affects response to divergent or specific treatment are unknown. Using multiple basal-like and claudin-low cell lines, we hereby demonstrate that RB-negative TNBC cell lines are highly sensitive to gamma-irradiation, and moderately more sensitive to doxorubicin and methotrexate compared to RB-positive TNBC cell lines. In contrast, RB1 status did not affect sensitivity of TNBC cells to multiple other drugs including cisplatin (CDDP), 5-fluorouracil, idarubicin, epirubicin, PRIMA-1^met, fludarabine and PD-0332991, some of which are used to treat TNBC patients. Moreover, a non-biased screen of ∼3400 compounds, including FDA-approved drugs, revealed similar sensitivity of RB-proficient and -deficient TNBC cells. Finally, ESA⁺/CD24^−/low/CD44⁺ cancer stem cells from RB-negative TNBC lines were consistently more sensitive to gamma-irradiation than RB-positive lines, whereas the effect of chemotherapy on the cancer stem cell fraction varied irrespective of RB1 expression. Our results suggest that patients carrying RB-deficient TNBCs would benefit from gamma-irradiation as well as doxorubicin and methotrexate therapy, but not necessarily from many other anti-neoplastic drugs.

High-throughput screen identifies disulfiram as a potential therapeutic for triple-negative breast cancer cells: interaction with IQ motif-containing factors

Triple-negative breast cancer (TNBC) represents an aggressive subtype, for which radiation and chemotherapy are the only options. Here we describe the identification of disulfiram, an FDA-approved drug used to treat alcoholism, as well as the related compound thiram, as the most potent growth inhibitors following high-throughput screens of 3185 compounds against multiple TNBC cell lines. The average IC₅₀ for disulfiram was ~300 nM. Drug affinity responsive target stability (DARTS) analysis identified IQ motif-containing factors IQGAP1 and MYH9 as direct binding targets of disulfiram. Indeed, knockdown of these factors reduced, though did not completely abolish, cell growth. Combination treatment with 4 different drugs commonly used to treat TNBC revealed that disulfiram synergizes most effectively with doxorubicin to inhibit cell growth of TNBC cells. Disulfiram and doxorubicin cooperated to induce cell death as well as cellular senescence, and targeted the ESA⁺/CD24^-/low/CD44⁺ cancer stem cell population. Our results suggest that disulfiram may be repurposed to treat TNBC in combination with doxorubicin.

Oxidative removal of arsenite by Fe(II)- and polyoxometalate (POM)-amended zero-valent aluminum (ZVAl) under oxic conditions

Abiotic transformation of As(III) to As(V) is possible which would decrease As toxicity. This study investigated the potential applications of zero-valent Al (ZVAl) or Al wastes, such as Al beverage cans, for converting As(III) to As(V) in an acidic solution under aerobic conditions. Results showed that As(III) could not be oxidized by ZVAl within 150 min reaction at pH 1 because of the presence of an oxide layer on ZVAl. However, 85 μM As(III) could be completely oxidized with the addition of Fe(II) or POM due to the generation of a Fenton reaction or the enhancement of H2O2 production, respectively, on the ZVAl surfaces. Because Fe(II) or polyoxometalate (POM) exhibited more stable at low pH and scavenged rapidly the H2O2 produced on the aerated ZVAl surfaces, OH radical productions were more efficient and As(III) was rapidly oxidized in the ZVAl/O2 system with theses two catalysts. The catalytic oxidation kinetics of As(III) in the presence of Fe(II) or POM were best described by zero-order reaction, and the rate constants increased with a decrease of pH from 2 to 1. Following the oxidative conversion of As(III) to As(V) in the ZVAl/Fe/O2 system, As(V) was removed by the newly formed hydrous Al/Fe precipitates by increasing the solution pH to 6. Nonetheless, the As(V) removal was incomplete in the ZVAl/POM/O2 system because the hydrolyzed products of POM, e.g., PO4(3-), inhibited As(V) removal due to the competitive adsorption of the oxyanion on Al precipitates. Discarded Al-based beverage cans exhibit a higher efficiency for As(III) oxidation and final As removal compared with that of ZVAl, and thus, the potential application of Al beverage cans to scavenge As in solutions is feasible.

mda-7/IL-24 expression inhibits breast cancer through upregulation of growth arrest-specific gene 3 (gas3) and disruption of β1 integrin function

Melanoma differentiation-associated gene (MDA)-7)/interleukin (IL)-24, a member of the IL-10 family of cytokines, inhibits growth of various human cancer cells, yet the underlying mechanism is largely unknown. Here, we report that mda-7/IL-24 efficiently suppresses the development of rat mammary tumors in vivo. Microarray analysis for genes differentially expressed in rat mammary tumor cells overexpressing MDA-7/IL-24 compared with those that do not express this cytokine identified growth arrest-specific gene-3 (gas3) as a target for mda-7/IL-24. Upregulation of gas3 by mda-7/IL-24 was STAT3 dependent. Induction of gas3 inhibited attachment and proliferation of tumor cells in vitro and in vivo by inhibiting the interaction of β1 integrin with fibronectin. A mutated GAS3, which is unable to bind β1 integrin, was also unable to inhibit fibronectin-mediated attachment and cell growth both in adherent and suspension cultures, suggesting that GAS3 exerts its effects through interaction with and regulation of β1 integrin. Thus, mda-7/IL-24 inhibits breast cancer growth, at least in part, through upregulation of GAS3 and disruption of β1 integrin function. Importantly, the expression of the mda-7/IL-24 receptor, IL-20R1, is highly correlated with GAS3 expression in human breast cancer (P = 1.02 × 10(-9)), and the incidence of metastases is significantly reduced in patients with HER2(+) breast cancer expressing high-levels of IL-20R1. Together, our results identify a novel MDA-7/IL-24-GAS3-β1integrin-fibronectin signaling pathway that suppresses breast cancer growth and can be targeted for therapy.

Effects of ozone and peroxone on algal separation via dispersed air flotation

Effects of pre-oxidation on algal separation by dispersed air flotation were examined. Ozone (O3) and peroxone (O3 and H2O2) could induce cell lysis, release of intracellular organic matter (IOM), and mineralization of organic substances. Separation efficiency of algal cells improved when pre-oxidized. Total of 76.4% algal cells was separated at 40 mg/L of N-cetyl-N-N-N-trimethylammonium bromide (CTAB), while 95% were separated after 30-min ozonation. Pre-oxidation by ozone and peroxone also enhanced flotation separation efficiency of dissolved organic carbon (DOC), polysaccharide, and protein, in which peroxone process exerted more significantly than O3. Two main mechanisms were involved in flotation separation of unoxidized algal suspension, namely hydrophobic cell surface and cell flocculation resulting from CTAB adsorption. However, flocculation by CTAB was hindered for pre-oxidized algal suspensions. It implied that the compositional changes in extracellular organic matter (EOM) by pre-oxidation were more determined for flotation separation of pre-oxidized cells.

Effect of O3 and O3/H2O2 on algae harvesting using chitosan

We examined the effects of pre-oxidation using ozone (O3) and a combination of O3 and hydrogen peroxide (O3/H2O2) on algae suspensions and their harvesting. Inactivation of algae cells, release of intracellular organic matter (IOM), mineralization of extracellular organic matter (EOM), and changes in molecular weight distribution of EOM were found after pre-oxidation. Enhanced separation efficiency of turbidity, dissolved organic carbon (DOC), protein, and polysaccharide using chitosan and polyaluminum chloride (PACl) was found after pre-oxidation, especially when algae cells were subject to O3/H2O2. Chitosan showed higher efficiency than PACl. Judging from the remarkable increase in floc size, it was proposed that released IOM formed complexes with cationic chitosan and resulted in enhanced dual flocculation and facilitated algae separation.

Abstract P1-04-05: Role of the Rb and p53 Tumor Suppressor Pathways in Mammary Tumorigenesis

The retinoblastoma (Rb) and p53 tumor suppressor pathways are frequently altered in human malignancies including breast cancer. To investigate the role of these pathways in mammary tumorigenesis, we crossed mice expressing Cre recombinase in the mammary epithelium (MMTV-Cre) with mice harboring Rb and p53 floxed alleles to generate MMTV-Cre:Rbf/f:p53f/f mutant mice. Combined somatic loss of Rb and p53 led to the formation of aggressive triple-negative tumors (ER−, PR−, HER2−) that often displayed features of an epithelial to mesenchymal transition (EMT) including sarcomatoid differentiation and high expression of the mesenchymal marker N-Cadherin. Molecular profiling revealed Rb/p53 deficient tumors shared similar gene expression profiles with mouse and human claudin-low breast cancers. Interstingly, limiting dilution transplantation analysis also suggests that Rb/p53 deficient claudin-low tumors are enriched for tumor-initiating cells (TICs).

To investigate the cellular origin of claudin-low tumors, the Rbf/f and p53f/f alleles were deleted within the luminal and basal compartments of the mammary gland using a Cre-expressing adenovirus (Ad-Cre) and CD24-CD49f-based FACS analysis. The different cellular fractions were then transplanted into the cleared mammary fat pad of recipient mice which are currently being monitored for tumor development.

Finally, primary cell lines isolated from Rb/p53 deficient mammary tumors were used in conjunction with high-throughput chemical and genetic screens to identify new therapeutic targets. A primary screen of 260 kinase inhibitors and 312 FDA-approved off-patent drugs has identified novel candidates and a genome wide negative selection (‘drop-out’) screen is currently in progress.

Ultimately, the results of this research will provide important insight into the biology of triple-negative breast cancer and will lead to the identification of novel therapeutic targets for the treatment of patients living with this disease.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-04-05.

Chromate reduction on humic acid derived from a peat soil--exploration of the activated sites on HAs for chromate removal

Humic substances are a major component of soil organic matter that influence the behavior and fate of heavy metals such as Cr(VI), a toxic and carcinogenic element. In the study, a repetitive extraction technique was used to fractionate humic acids (HAs) from a peat soil into three fractions (denoted as F1, F2, and F3), and the relative importance of O-containing aromatic and aliphatic domains in humic substances for scavenging Cr(VI) was addressed at pH 1. Spectroscopic analyses indicated that the concentrations of aromatic C and O-containing functional groups decreased with a progressive extraction as follows: F1>F2>F3. Cr(VI) removal by HA proceeded slowly, but it was enhanced when light was applied due to the production of efficient reductants, such as superoxide radical and H(2)O(2), for Cr(VI). Higher aromatic- and O-containing F1 fraction exhibited a greater efficiency for Cr(VI) reduction (with a removal rate of ca. 2.89 mmol g(-1) HA under illumination for 3 h). (13)C NMR and FTIR spectra further demonstrated that the carboxyl groups were primarily responsible for Cr(VI) reduction. This study implied the mobility and fate of Cr(VI) would be greatly inhibited in the environments containing such organic groups.

Observation of electron-antineutrino disappearance at Daya Bay

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.

Chromate removal as influenced by the structural changes of soil components upon carbonization at different temperatures

Surface fire could induce heat transferring into the soil, creating a carbonized environment, which may alter the chemical compositions of soil organic matters (SOM). In the study, a surface soil was carbonized at up to 600 °C with limited air to simulate soils experiencing a surface fire, and Cr(VI) removal on the carbonized soils was investigated. NMR and FTIR analyses demonstrated a remarkable change of SOM structures at 300-400 °C. TGA-MS spectra indicated that (e.g. C(2)H(4), CH(3)OH and C(3)H(8)) were the major components in the evolved gases from the pyrolyzed soil. A maximum amount of Cr(VI) removal (ca. 4 mg g(-1) soil) occurred for the 200 °C-carbonized soils, attributed mainly to a significant increase of Cr(VI) reduction by 0.1 M KCl extractable organic carbon (EOC) with abundant carboxylic groups. Nonetheless, the formation of aromatic C upon carbonization of the soil at >400 °C may be responsible for Cr(VI) reduction.