Variability in N2O emission controls among different ponds within a hilly watershed.

While it is well established that small water bodies like ponds play a disproportionately large role in contributing to N2O emissions, few studies have focused on lowland ponds in hilly watersheds. Here, we explored the characteristics of N2O concentrations and emissions from various typical ponds (village, tea, forested, and aquaculture ponds) in a hilly watershed and examined the specific controls influencing N2O production. Our findings revealed that tea ponds exhibited the highest N2O flux (8.42 ± 8.23 µmol m-2 d-1), which was 2.8 to 3.3 times greater than other types of ponds. Remarkable seasonal variations were observed in tea and forested ponds due to the seasonality of nutrient-enriched runoff, whereas such variations were less pronounced in village and aquaculture ponds. Key factors such as nitrogen levels, temperature, and dissolved oxygen (DO) emerged as the primary controls of N2O concentrations in ponds, heavily influenced by land use and human activities in their drainage areas. Specifically, N2O production in tea and aquaculture ponds was driven by N inputs from fertilization and feed, respectively, while DO levels governed the process in village and forested ponds, influenced by abundant algae and forest vegetation. This study emphasizes that environmental factors predominantly drive N2O production in ponds within hilly watersheds, but land use in the pond drainages acts as an indirect yet crucial influence. This highlights the need for future research to develop targeted emission reduction strategies based on land use to effectively mitigate N2O emissions, promising a path toward more sustainable and climate-friendly watershed management.

Preclinical evaluation of protein synthesis inhibitor omacetaxine in pediatric brainstem gliomas.

Background: Diffuse intrinsic pontine gliomas (DIPGs) pose a significant challenge as a highly aggressive and currently incurable form of pediatric brain cancer, necessitating the development of novel therapeutic strategies. Omacetaxine, an FDA-approved protein synthesis inhibitor for treating certain hematological malignancies, was investigated for its potential antitumor effects against preclinical DIPG models. Methods: We employed primary DIPG cultures to study omacetaxine's cytotoxicity and its impact on colony formation. Annexin V staining and flow cytometry assessed apoptosis. Wound healing assays evaluated migration, while western blotting determined inhibition of oncogenic proteins. We tested omacetaxine's therapeutic efficacy in an orthotopic DIPG model and assessed brain penetration using mass spectrometry. Results: We found a pronounced cytotoxic activity of omacetaxine against DIPG neurospheres, with low IC50 values of approximately 20 nM. Omacetaxine exerted its anti-proliferative effect by inhibiting protein synthesis and the induction of apoptotic pathways, evidenced by significant elevated levels of cleaved caspase 3 and cleaved PARP, both key markers of apoptosis. Omacetaxine effectively targeted oncogenic players such as PDGFRα and PI3K without additional effects on the mTOR signaling pathway. Furthermore, our study revealed the inhibitory effects of omacetaxine on cell migration, and a significant reduction in integrin/FAK signaling, which plays a crucial role in tumor progression and metastasis. Conclusions: Despite these promising in vitro effects, omacetaxine's efficacy in an orthotopic DIPG model was limited due to inadequate penetration across the blood-brain barrier. As such, further research and advancements are crucial to improve the drug's brain penetration, thus enhancing its overall therapeutic potential.

CdS Nanoparticles Supported by Cobalt@Carbon-Derived MOFs for the Improved Adsorption and Photodegradation of Ciprofloxacin.

The design and synthesis of efficient photocatalysts that promote the degradation of organic pollutants in water have attracted extensive attention in recent years. In this work, CdS nanoparticles are grown in situ on Co@C derived from metal-organic frameworks. The resulting hierarchical CdS/Co@C nanostructures are evaluated in terms of their adsorption and photocatalytic ciprofloxacin degradation efficiency under visible-light irradiation. The results show that, apart from offering a large surface area (55.69 m2·g-1), the prepared material can effectively suppress the self-agglomeration of CdS and enhance the absorption of visible light. The CdS/Co@C-7 composite containing 7% wt Co@C has the highest photodegradation rate, and its activity is approximately 4.4 times greater than that of CdS alone. Moreover, this composite exhibits remarkable stability after three successive cycles of photocatalysis. The enhanced photocatalytic performance is largely ascribed to the rapid separation of electron-hole pairs and the effective electron transfer between CdS and Co@C, which is confirmed via electrochemical experiments and photoluminescence spectra. The active substance capture experiment and the electron spin resonance technique show that h+ is the main active entity implicated in the degradation of CIP, and accordingly, a possible mechanism of CIP photocatalytic degradation over CdS/Co@C is proposed. In general, this work presents a new perspective on designing novel photocatalysts that promote the degradation of organic pollutants in water.

A Novel Ultra-Low Work Function TbFx for High Efficiency Dopant-Free Silicon Solar Cells.

The ability of carrier selective contact is mainly determined by the surface passivation and work function for dopant-free materials applied in crystalline silicon (c-Si) solar cells, which have received considerable attention in recent years. In this contribution, a novel electron-selective material, lanthanide terbium trifluoride (TbFx ), with an ultra-low work function of 2.4 eV characteristic, is presented, allowing a low contact resistivity (ρc ) of ≈3 mΩ cm2 . Additionally, the insertion of ultrathin passivated SiOx layer deposited by PECVD between TbFx and n-Si resulted in ρc only increase slightly. SiOx /TbFx stack eliminated fermi pinning between aluminum and n-type c-Si (n-Si), which further enhanced the electron selectivity of TbFx on full-area contacts to n-Si. Last, SiOx /TbFx /Al electron-selective contacts significantly improves the open circuit voltage (Voc ) for silicon solar cells, but rarely impacts the short circuit current (Jsc ) and fill factor (FF), thus champion efficiency cell achieved approaching 22% power conversion efficiency (PCE). This study indicates a great potential for using lanthanide fluorides as electron-selective material in photovoltaic devices.

Delivery of PEGylated liposomal doxorubicin by bispecific antibodies improves treatment in models of high-risk childhood leukemia.

High-risk childhood leukemia has a poor prognosis because of treatment failure and toxic side effects of therapy. Drug encapsulation into liposomal nanocarriers has shown clinical success at improving biodistribution and tolerability of chemotherapy. However, enhancements in drug efficacy have been limited because of a lack of selectivity of the liposomal formulations for the cancer cells. Here, we report on the generation of bispecific antibodies (BsAbs) with dual binding to a leukemic cell receptor, such as CD19, CD20, CD22, or CD38, and methoxy polyethylene glycol (PEG) for the targeted delivery of PEGylated liposomal drugs to leukemia cells. This liposome targeting system follows a "mix-and-match" principle where BsAbs were selected on the specific receptors expressed on leukemia cells. BsAbs improved the targeting and cytotoxic activity of a clinically approved and low-toxic PEGylated liposomal formulation of doxorubicin (Caelyx) toward leukemia cell lines and patient-derived samples that are immunophenotypically heterogeneous and representative of high-risk subtypes of childhood leukemia. BsAb-assisted improvements in leukemia cell targeting and cytotoxic potency of Caelyx correlated with receptor expression and were minimally detrimental in vitro and in vivo toward expansion and functionality of normal peripheral blood mononuclear cells and hematopoietic progenitors. Targeted delivery of Caelyx using BsAbs further enhanced leukemia suppression while reducing drug accumulation in the heart and kidneys and extended overall survival in patient-derived xenograft models of high-risk childhood leukemia. Our methodology using BsAbs therefore represents an attractive targeting platform to potentiate the therapeutic efficacy and safety of liposomal drugs for improved treatment of high-risk leukemia.

Facile Synthesis of 2D/2D Ti2C3/ZnIn2S4 Heterostructure for Enhanced Photocatalytic Hydrogen Generation.

ZnIn2S4, a novel two-dimensional visible light-responsive photocatalyst, has attracted much attention in the photocatalytic evolution of H2 under visible light irradiation due to its attractive intrinsic photoelectric properties and geometric configuration. However, ZnIn2S4 still has severe charge recombination, which results in moderate photocatalytic performance. Herein, we report the successful synthesis of 2D/2D ZnIn2S4/Ti3C2 nanocomposites by a facile one-step hydrothermal method. The efficiency of the nanocomposites in photocatalytic hydrogen evolution under visible light irradiation was also evaluated for different ratios of Ti3C2, and the optimal photocatalytic activity was achieved at 5% Ti3C2. Importantly, the activity was significantly higher than that of pure ZnIn2S4, ZnIn2S4/Pt, and ZnIn2S4/graphene. The enhanced photocatalytic activity is mainly due to the close interfacial contact between Ti3C2 and ZnIn2S4 nanosheets, which amplifies the transport of photogenerated electrons and enhances the separation of photogenerated carriers. This research describes a novel approach for the synthesis of 2D MXenes for photocatalytic hydrogen production and expands the utility of MXene composite materials in the fields of energy storage and conversion.

Inclusion of the in-chain sulfur in 3-thiaCTU increases the efficiency of mitochondrial targeting and cell killing by anticancer aryl-urea fatty acids.

Mitochondria in tumor cells are functionally different from those in normal cells and could be targeted to develop new anticancer agents. We showed recently that the aryl-ureido fatty acid CTU is the prototype of a new class of mitochondrion-targeted agents that kill cancer cells by increasing the production of reactive oxygen species (ROS), activating endoplasmic reticulum (ER)-stress and promoting apoptosis. However, prolonged treatment with high doses of CTU were required for in vivo anti-tumor activity. Thus, new strategies are now required to produce agents that have enhanced anticancer activity over CTU. In the present study we prepared a novel aryl-urea termed 3-thiaCTU, that contained an in-chain sulfur heteroatom, for evaluation in tumor cell lines and in mice carrying tumor xenografts. The principal finding to emerge was that 3-thiaCTU was several-fold more active than CTU in the activation of aryl-urea mechanisms that promoted cancer cell killing. Thus, in in vitro studies 3-thiaCTU disrupted the mitochondrial membrane potential, increased ROS production, activated ER-stress and promoted tumor cell apoptosis more effectively than CTU. 3-ThiaCTU was also significantly more active than CTUin vivo in mice that carried MDA-MB-231 cell xenografts. Compared to CTU, 3-thiaCTU prevented tumor growth more effectively and at much lower doses. These findings indicate that, in comparison to CTU, 3-thiaCTU is an aryl-urea with markedly enhanced activity that could now be suitable for development as a novel anticancer agent.

Preclinical Evaluation of Ixabepilone in Combination with VEGF Receptor and PARP Inhibitors in Taxane-Sensitive and Taxane-Resistant MDA-MB-231 Breast Cancer Cells.

Long-term use of cytotoxic agents promotes drug-resistance in triple-negative breast cancer (TNBC). The identification of new drug combinations with efficacy against drug-resistant TNBC cells in vitro is valuable in developing new clinical strategies to produce further cancer remissions. We undertook combination analysis of the cytotoxic agent ixabepilone with small molecule inhibitors of vascular endothelial growth factor receptor (VEGFR) and poly (ADP-ribose) polymerase (PARP) in taxane-sensitive (231C) and taxane-resistant (TXT) MDA-MB-231-derived cells. As single agents, the VEGFR inhibitors cediranib and bosutinib decreased both 231C and TXT cell viability, but four other VEGFR inhibitors and two PARP inhibitors were less effective. Combinations of ixabepilone with either cediranib or bosutinib synergistically decreased 231C cell viability. However, only the ixabepilone/cediranib combination was synergistic in TXT cells, with predicted 15.3-fold and 1.65-fold clinical dose reductions for ixabepilone and cediranib, respectively. Flow cytometry and immunoblotting were used to further evaluate the loss of cell viability. Thus, TXT cell killing by ixabepilone/cediranib was enhanced over ixabepilone alone, and expression of proapoptotic cleaved caspase-3 and the Bak/Bcl-2 protein ratio were increased. These findings suggest that the synergistic activity of the ixabepilone/cediranib combination in taxane-sensitive and taxane-resistant cells may warrant clinical evaluation in TNBC patients.

Biotemplated CdS Nano-Aggregate Networks for Highly Effective Visible-Light Photocatalytic Hydrogen Production.

In the last few decades, many new synthesis techniques have been developed in order to obtain an effective visible-light responsive photocatalyst for hydrogen production by water splitting. Among these new approaches, the biotemplated synthesis method has aroused much attention because of its unique advantages in preparing materials with special morphology and structure. In this work, Hydrilla verticillata (L. f.) Royle was used as a biotemplate to synthesize a CdS photocatalyst. The as-synthesized sample had the microstructure of nano-scaled aggregate networks and its activity for photocatalytic hydrogen production was six times higher than that of CdS synthesized without a template in an Na2S-Na2SO3 sacrificial system. The use of Pt and PdS as cocatalysts further improved the hydrogen production rate to 14.86 mmol/g·h under visible-light (λ ≥ 420 nm) irradiation, so the hydrogen production can be directly observed by the naked eye. The results of characterization showed that the as-synthesized CdS photocatalyst has a high specific surface area and narrow band gap, which is favorable for light absorption and photocatalytic reaction. This work provides a new way to search for efficient visible-light catalysts and confirms the uniqueness of a biotemplated synthesis method in obtaining specially structured materials.

The aryl-ureido fatty acid CTU activates endoplasmic reticulum stress and PERK/NOXA-mediated apoptosis in tumor cells by a dual mitochondrial-targeting mechanism.

The cancer cell mitochondrion is functionally different from that in normal cells and could be targeted to develop novel experimental therapeutics. The aryl-ureido fatty acid CTU (16({[4-chloro-3-(trifluoromethyl)phenyl]-carbamoyl}amino)hexadecanoic acid) is the prototype of a new class of mitochondrion-targeted agents that kill cancer cells. Here we show that CTU rapidly depolarized the inner mitochondrial membrane, selectively inhibited complex III of the electron transport chain and increased reactive oxygen species (ROS) production. From RNA-seq analysis, endoplasmic reticulum (ER)-stress was a major activated pathway in CTU-treated cells and in MDA-MB-231 tumor xenografts from CTU-treated nu/nu mice. Mitochondrion-derived ROS activated the PERK-linked ER-stress pathway and induced the BH3-only protein NOXA leading to outer mitochondrial membrane (OMM) disruption. The lipid peroxyl scavenger α-tocopherol attenuated CTU-dependent ER-stress and apoptosis which confirmed the critical role of ROS. Oleic acid protected against CTU-mediated apoptosis by activating Mcl-1 expression, which increased NOXA sequestration and prevented OMM disruption. Taken together, CTU both uncouples mitochondrial electron transport and activates ROS production which promotes ER-stress-dependent OMM disruption and tumor cell death. Dual-mitochondrial targeting agents like CTU offer a novel approach for development of new anti-cancer therapeutics.

PTU, a novel ureido-fatty acid, inhibits MDA-MB-231 cell invasion and dissemination by modulating Wnt5a secretion and cytoskeletal signaling.

Migration and invasion promote tumor cell metastasis, which is the leading cause of cancer death. At present there are no effective treatments. Epidemiological studies have suggested that ω-3 polyunsaturated fatty acids (PUFA) may decrease cancer aggressiveness. In recent studies epoxide metabolites of ω-3 PUFA exhibited anti-cancer activity, although increased in vivo stability is required to develop useful drugs. Here we synthesized novel stabilized ureido-fatty acid ω-3 epoxide isosteres and found that one analogue - p-tolyl-ureidopalmitic acid (PTU) - inhibited migration and invasion by MDA-MB-231 breast cancer cells in vitro and in vivo in xenografted nu/nu mice. From proteomics analysis of PTU-treated cells major regulated pathways were linked to the actin cytoskeleton and actin-based motility. The principal finding was that PTU impaired the formation of actin protrusions by decreasing the secretion of Wnt5a, which dysregulated the Wnt/planar cell polarity (PCP) pathway and actin cytoskeletal dynamics. Exogenous Wnt5a restored invasion and Wnt/PCP signalling in PTU-treated cells. PTU is the prototype of a novel class of agents that selectively dysregulate the Wnt/PCP pathway by inhibiting Wnt5a secretion and actin dynamics to impair MDA-MB-231 cell migration and invasion.

Carbon Chain Length Modulates MDA-MB-231 Breast Cancer Cell Killing Mechanisms by Mitochondrially Targeted Aryl-Urea Fatty Acids.

Targeting the tumor cell mitochondrion could produce novel anticancer agents. We designed an aryl-urea fatty acid (1 g; 16({[4-chloro-3-(trifluoromethyl)phenyl]carbamoyl}amino)hexadecanoic acid) that disrupted the mitochondrion and decreased MDA-MB-231 breast cancer cell viability. To optimize the aryl-ureas the present study evaluated mitochondrial targeting by 1 g analogues containing alkyl chains between 10-17 carbons. Using the dye JC-1, the C12-C17 analogues efficiently disrupted the mitochondrial membrane potential (IC50 s 3.5±1.2 to 7.6±1.1 µM) and impaired ATP production; shorter analogues were less active. 7-Aminoactinomycin D/annexin V staining and flow cytometry showed that these agents activated the killing mechanisms of necrosis and apoptosis to varying extents (7-aminoactinomycin D/annexin V staining ratios 4.3-6.0). Indeed, 1 g and its C17 analogue preferentially activated necrosis and apoptosis, respectively (ratios 2.1 and 16). Taken together, alkyl chain length is a determinant of mitochondrial targeting by aryl-ureas and can be varied to develop analogues that activate apoptosis or necrosis in a regulated fashion.

Facile direct synthesis of graphene-wrapped ZnO nanospheres from cyanobacterial cells.

Graphene-based composite materials are versatile but not easily procurable. Cyanobacterial cells, an outgrowth of eutrophic freshwater lake, were simultaneously employed as a template for the growth of ZnO nanoparticles and as a biomass carbon source for graphene sheets, resulting in chlorophyll-containing graphene-wrapped ZnO nanospheres.

Efficient Charge Carrier Separation in l-Alanine Acids Derived N-TiO2 Nanospheres: The Role of Oxygen Vacancies in Tetrahedral Ti4+ Sites.

N-doped TiO2 with oxygen vacancies exhibits many advantages for photocatalysis, such as enhanced visible light absorbency, inhibition of the photogenerated charge carrier recombination, etc. However, preparation of N-doped TiO2 with oxygen vacancies under mild conditions is still a challenge. Herein, N-doped TiO2 nanospheres with tetrahedral Ti4+ sites were synthesized by using dodecylamine as template and assisted by l-alanine acids. The obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectra (UV-Vis DRS). It was found that the dodecylamine as a neutral surfactant controlled the structure of TiO2 spherical, while l-alanine acids provided a nitrogen source. The existence of tetrahedral Ti4+ sites in N-doped TiO2 was also confirmed. The N-doped TiO2 sample with tetrahedral Ti4+ sites exhibited significantly improved photocatalytic performance for degradation of methylene blue solution under UV light or visible light irradiation. A combined time-resolved infrared (IR) spectroscopy study reveals that the enhanced photocatalytic performance could be attributed to a large amount of photogenerated charge carriers and efficient charge separation. It is demonstrated that the shallow donor state produced by oxygen vacancies of tetrahedral Ti4+ sites can effectively promote separation of charge carriers besides capturing electrons.

Aryl-urea fatty acids that activate the p38 MAP kinase and down-regulate multiple cyclins decrease the viability of MDA-MB-231 breast cancer cells.

We recently developed a novel aryl-urea fatty acid (CTU; 16({[4-chloro-3-(trifluoromethyl)phenyl]carbamoyl}amino)hexadecanoic acid) that impaired the viability of MDA-MB-231 breast cancer cells in vitro and in mouse xenograft models in vivo. At present there is a deficiency of information on the structural requirements for the activity of CTU. Our initial study suggested that electron withdrawing groups were required on the aryl ring, and in this study we further evaluated the influence of the electronic properties of aromatic substitution on the capacity of CTU analogues to decrease MDA-MB-231 breast cancer cell viability. Analogues that contained strong electron-withdrawing groups in the meta- and para-positions of the aryl ring exhibited improved activity over CTU. Effective analogues down-regulated the cyclins D1, E1 and B1, and the cyclin-dependent kinases (CDKs) 4 and 6, that form complexes to coordinate cell cycle progression. Active CTU analogues also stimulated the phosphorylation and activation of the p38 MAP kinase signalling pathway in cells and both decreased proliferation (5-bromo-2'-deoxyuridine (brdU) incorporation) and activated apoptosis (executioner caspase-3/7 activity). These agents offer a new approach to target the cell cycle at multiple phases in order to efficiently prevent cancer cell expansion. Inclusion of the present structural information in drug design approaches could enhance the development of optimal analogues of aryl-urea fatty acids as potential anti-cancer agents.

Nanoemulsion-Enabled Oral Delivery of Novel Anticancer ω-3 Fatty Acid Derivatives.

Lipid-based drugs are emerging as an interesting class of novel anticancer drugs with the potential to target specific cancer cell metabolic pathways linked to their proliferation and invasiveness. In particular, ω-3 polyunsaturated fatty acids (PUFA) derivatives such as epoxides and their bioisosteres have demonstrated the potential to suppress growth and promote apoptosis in triple-negative human breast cancer cells MDA-MB-231. In this study, 16-(4'-chloro-3'-trifluorophenyl)carbamoylamino]hexadecanoic acid (ClFPh-CHA), an anticancer lipid derived from ω-3,17,18-epoxyeicosanoic acid, was formulated as a stable nanoemulsion with size around 150 nm and narrow droplet size distribution (PDI < 0.200) through phase-inversion emulsification process followed by high pressure homogenization in view of an oral administration. The ClFPh-CHA-loaded nanoemulsions were able to significantly decrease the relative tumor volume in mice bearing an intramammary tumor xenograft at all doses tested (2.5, 10 and 40 mg/kg) after 32 days of daily oral administration. Furthermore, absolute tumor weight was decreased to 50% of untreated control at 10 and 40 mg/kg, while intraperitoneal administration could achieve a significant reduction only at the highest dose of 40 mg/kg. Results suggest that oral administration of ClFPh-CHA formulated as a nanoemulsion has a sufficient bioavailability to provide an anticancer effect in mice and that the activity is at least equal if not superior to that obtained by a conventional parenteral administration of equivalent doses of the same drug.

[Influences of Anthropogenic Activities on the Community Structure of N-DAMO Bacteria in the North Canal].

Stream ecosystems are the primary receivers of nutrients and organic carbon exported from terrestrial ecosystems and are profoundly influenced by the land of the surrounding landscape. Anthropogenic activities increased the nutrient and organic carbon levels in both stream and benthic biofilms, which are closely related to the differences in the N-DAMO (Nitrate/nitrite-dependent anaerobic methane oxidation) bacterial communities. We studied N-DAMO bacterial communities in streams flowing through anthropogenic land in the city of Beijing. The results showed that anthropogenic activities increase the nutrient and organic carbon levels both midstream and downstream; these are closely related to the difference in the N-DAMO bacterial communities. Phylogenetic analysis revealed that most of the cloned 16S rRNA and pmoA sequences in the North Canal were similar to those recovered from activated sludge and wastewater. The effect of nitrogen on N-DAMO bacteria in the North Canal mainly depended on the main form of available nitrogen and the source of pollutant. Moreover, N-DAMO bacteria present downstream of the North Canal, had a more connected and modular microbial network than those present midstream, where bacterial communities with tightly connected species that were shown to be more vulnerable and sensitive to various disturbances were found.

A Novel Arylurea Fatty Acid That Targets the Mitochondrion and Depletes Cardiolipin To Promote Killing of Breast Cancer Cells.

Cancer cell mitochondria are promising anticancer drug targets because they control cell death and are structurally and functionally different from normal cell mitochondria. We synthesized arylurea fatty acids and found that the analogue 16-({[4-chloro-3-(trifluoromethyl)phenyl]carbamoyl}amino)hexadecanoic acid (13b) decreased proliferation and activated apoptosis in MDA-MB-231 breast cancer cells in vitro and in vivo. In mechanistic studies 13b emerged as the prototype of a novel class of mitochondrion-targeted agents that deplete cardiolipin and promote cancer cell death.

A novel synthetic analogue of ω-3 17,18-epoxyeicosatetraenoic acid activates TNF receptor-1/ASK1/JNK signaling to promote apoptosis in human breast cancer cells.

A saturated analog of the cytochrome P450-mediated ω-3-17,18-epoxide of ω-3-eicosapentaenoic acid (C20E) activated apoptosis in human triple-negative MDA-MB-231 breast cancer cells. This study evaluated the apoptotic mechanism of C20E. Increased cytosolic cytochrome c expression and altered expression of pro- and antiapoptotic B-cell lymphoma-2 proteins indicated activation of the mitochondrial pathway. Caspase-3 activation by C20E was prevented by pharmacological inhibition and silencing of the JNK and p38 MAP kinases (MAPK), upstream MAPK kinases MKK4 and MKK7, and the upstream MAPK kinase kinase apoptosis signal-regulating kinase 1 (ASK1). Silencing of the death receptor TNF receptor 1 (TNFR1), but not Fas, DR4, or DR5, and the adapters TRADD and TNF receptor-associated factor 2, but not Fas-associated death domain, prevented C20E-mediated apoptosis. B-cell lymphoma-2 homology 3-interacting domain death agonist (Bid) cleavage by JNK/p38 MAPK linked the extrinsic and mitochondrial pathways of apoptosis. In further studies, an antibody against the extracellular domain of TNFR1 prevented apoptosis by TNF-α but not C20E. These findings suggest that C20E acts intracellularly at TNFR1 to activate ASK1-MKK4/7-JNK/p38 MAPK signaling and to promote Bid-dependent mitochondrial disruption and apoptosis. In in vivo studies, tumors isolated from C20E-treated nu/nu mice carrying MDA-MB-231 xenografts showed increased TUNEL staining and decreased Ki67 staining, reflecting increased apoptosis and decreased proliferation, respectively. ω-3-Epoxy fatty acids like C20E could be incorporated into treatments for triple-negative breast cancers.-Dyari, H. R. E., Rawling, T., Chen, Y., Sudarmana, W., Bourget, K., Dwyer, J. M., Allison, S. E., Murray, M. A novel synthetic analogue of ω-3 17,18-epoxyeicosatetraenoic acid activates TNF receptor-1/ASK1/JNK signaling to promote apoptosis in human breast cancer cells.

Activation of ALDH1A1 in MDA-MB-468 breast cancer cells that over-express CYP2J2 protects against paclitaxel-dependent cell death mediated by reactive oxygen species.

Cytochrome P450 2J2 (CYP2J2) expression is elevated in breast and other tumours, and is known to be protective against cytotoxic agents that may be used in cancer chemotherapy. This study evaluated the mechanisms by which MDA-MB-468 breast cancer cells that stably expressed CYP2J2 (MDA-2J2 cells) were protected against killing by the anti-cancer agent paclitaxel. Compared to control cells caspase-3/7 activation by paclitaxel was lower in MDA-2J2 cells, while cell proliferation and colony formation following paclitaxel treatment were increased. Basal lipid peroxidation was lower in MDA-2J2 cells than in control cells, and the paclitaxel-mediated increase in peroxidation was attenuated. The mitochondrial complex III inhibitor antimycin A modulated basal and paclitaxel-activated reactive oxygen species (ROS) formation in control cells; paclitaxel-activated ROS production was also modulated by the NADPH oxidase inhibitor diphenyleneiodonium. Paclitaxel increased the formation of protein adducts by the reactive aldehyde 4-hydroxynonenal that is produced by lipid peroxidation; adduct formation was attenuated in MDA-2J2 cells. ALDH1A1 expression and activity was strongly upregulated in MDA-2J2 cells that was attributed to CYP2J2-derived 14,15-epoxyeicosatrienoic acid (14,15-EET); the 8,9- and 11,12-EET regioisomers did not activate ALDH1A1 expression. Silencing of ALDH1A1 restored the sensitivity of MDA-2J2 cells to paclitaxel, as indicated by a more pronounced decrease in proliferation, and greater increases in caspase activity and formation of ROS to levels comparable with control cells. Similar findings were observed with doxorubicin, sorafenib and staurosporine, that also promoted ROS-mediated cell death that was attenuated in MDA-2J2 cells and reversed by ALDH1A1 gene silencing. These findings implicate ALDH1A1 as an important gene that is activated in MDA-MB-468-derived cells that contain high levels of CYP2J2. ALDH1A1 modulates the production of ROS by anti-cancer agents such as paclitaxel and diminishes their efficacy. Future approaches could adapt this information to facilitate the targeting of ALDH1A1 to promote the efficacy of ROS-generating cytotoxic agents and enhance the treatment of breast cancer.