Phthalic acid chemical probes synthesized for protein-protein interaction analysis

Antioxidant Capacity and Protective Effects on H2O2-Induced Oxidative Damage in PC12 Cells of the Active Fraction of Brassica rapa L

Brassica rapa L. (BR), a traditional biennial herb belonging to the Brassica species of Brassicaceae, has been widely used for functions of anti-inflammatory, antitumor, antioxidation, antiaging, and regulation of immunity. In this study, antioxidant activity and protective effects on H2O2-induced oxidative damage in PC12 cells of the active fractions of BR were investigated in vitro. Among all active fractions, the ethyl acetate fraction of ethanol extract from BR (BREE-Ea) showed the strongest antioxidant activity. Additionally, it was noted that BREE-Ea and n-butyl alcohol fraction of ethanol extract from BR (BREE-Ba) both have protective effects in oxidatively damaged PC12 cells, while BREE-Ea displayed the best protective effect in all determined experimental doses. Furthermore, flow cytometry (DCFH-DA staining) analysis indicated that BREE-Ea could reduce the H2O2-induced apoptosis in PC12 cells by reducing the production of intracellular reactive oxygen species (ROS) and increasing enzymatic activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Moreover, BREE-Ea could decrease the malondialdehyde (MDA) content and reduce the release of extracellular lactic dehydrogenase (LDH) from H2O2-induced PC12 cells. All these results demonstrate that BREE-Ea has a good antioxidant capacity and protective effect on PC12 cells against apoptosis induced by H2O2 and that it can be used as a good edible antioxidant to improve the body's endogenous antioxidant defense.

The influence of silica nanoparticle geometry on the interfacial interactions of organic molecules: a molecular dynamics study

The role of nanoparticle shape in the interaction and adsorption of organic molecules on the particle surface is an unexplored area. On the other hand, such knowledge is not only vital for a basic understanding of organic molecule interaction with nanoparticle surfaces but also essential for evaluating the cellular uptake of nanoparticles for living organisms. The current study investigates the role of silica nanoparticle shape in the interactions of phthalic acid organic molecules by using molecular dynamics simulations. Silica nanoparticles of two different geometries namely spheroid and cuboid with varying charge densities along with protonated and deprotonated phthalic acid molecules are studied. The adsorption characteristics of phthalic acid molecules on these nanoparticles have been analysed under different aquatic environments. The interactions of phthalic acid molecules, water molecules and ions were found to be different for spheroid and cubic shaped particles at pH values of 2-3, 7 and 9-10. The interaction of phthalic acid molecules with cubical silica nanoparticles is enhanced compared to the spherical shape particles. Such an enhanced interaction was seen when the silica surface is neutral, pH 2-3 and when the silica surface is charged at pH 7 and pH 9-10 in the presence of 0.5 M NaCl electrolyte. The cuboid-shaped silica also exhibited more hydrophilicity and less negative surface potential compared to spheroid shaped particles at pH 9-10. This is due to the enhanced condensation of Na⁺ counter-ions at the cuboid nanoparticle solution interface as to the interface of spheroid particles, which is well in agreement with Manning's theory of counter-ion condensation. Simulation results presented in this study indicate that the shape of the silica nanoparticle has significant influence on the interaction of water molecules, counter-ions and organic molecules which consequently determine the adsorption behaviour of organic molecules on the nanoparticle surface.

DEHP mediates drug resistance by directly targeting AhR in human breast cancer

Resistance to chemotherapy and hormonal therapy is a major clinical problem in breast cancer medicine, especially for cancer metastasis and recurrence. Di(2-ethylhexyl)phthalate (DEHP) affects drug resistance by an unknown mechanism of action. Here we analyzed breast cancer patients (N = 457) and found that Σ₄MEHP (the sum of MEHP, MEHHP, MECPP and MEOHP concentrations) in urine was significantly higher (P = 0.018) in the recurrent breast cancer group compared with non-recurrent patients. Σ₄MEHP-High was positively and significantly correlated with tumor stage (P = 0.005), lymph node status (P = 0.001), estrogen receptor status (P = 0.010), Her2/Neu status (P = 0.004), recurrence (P = 0.000) and tumor size (P = 0.002), as well as an independent prognostic marker (OR = 1.868; 95% CI = 1.424-2.451; P < 0.000) associated with poor survival rates based on a positive Her2/Neu status (P = 0.035). In addition, we found that DEHP inhibited paclitaxel and doxorubicin effects in breast cancer cell lines MCF-7 and MDA-MB-231 and in zebrafish and mouse tumor initiation models. DEHP induced trefoil factor 3 (TFF3) expression through the vinculin/aryl hydrocarbon receptor (AhR)/ERK signaling pathway and induced CYP2D6, CYP2C8 and CYP3A4 expression through the AhR genomic pathway to increase the epithelial-mesenchymal transition (EMT) and doxorubicin metabolism, respectably. DEHP mediated AhR-related alterations in estrogen receptor expression through the ubiquitination system, which decreased tamoxifen effects in AhR knockout mice. These findings suggest a novel therapeutic avenue by targeting AhR in drug-resistant and recurrent breast cancer.

Impacts of Endocrine Disruptor di-n-Butyl Phthalate Ester on Microalga Chlorella vulgaris Verified by Approaches of Proteomics and Gene Ontology

Di-n-butyl phthalate (DBP) is an extensively used plasticizer. Most investigations on DBP have been concentrated on its environmental distribution and toxicity to humans. However, information on the effects of plasticizers on algal species is scarce. This study verified the impacts of endocrine disruptor di-n-butyl phthalate ester on microalga Chlorella vulgaris by approaches of proteomics and gene ontology. The algal acute biotoxicity results showed that the 24h-EC50 of DBP for C. vulgaris was 4.95 mg L^-1, which caused a decrease in the chlorophyll a content and an increase in the DBP concentration of C. vulgaris. Proteomic analysis led to the identification of 1257 C. vulgaris proteins. Sixty-one more proteins showed increased expression, compared to proteins with decreased expression. This result illustrates that exposure to DBP generally enhances protein expression in C. vulgaris. GO annotation showed that both acetolactate synthase (ALS) and GDP-L-fucose synthase 2 (GER2) decreased more than 1.5-fold after exposure to DBP. These effects could inhibit both the valine biosynthetic process and the nucleotide-sugar metabolic process in C. vulgaris. The results of this study demonstrate that DBP could inhibit growth and cause significant changes to the biosynthesis-relevant proteins in C. vulgaris.

The use of chemical probes to detect the proteomics of renal tubular injury induced by maleic acid

Maleic acid (MA), an industrial raw material, was found to be illegally added to edible starch-based food products in Taiwan in 2013, a practice unheard of in most of the world. MA has been associated with renal dysfunction in many experimental animal studies. In this study, we developed chemical probes to investigate protein-protein interactions between MA and renal proteins. In the fabrication of the MA probes, we used silicon dioxide (SiO₂) modified with a silanized linker (3-aminopropyl triethoxyslane, APTES) to generate MA with APTES-SiO₂ particles. The probes were then incubated with the cell lysates of normal human kidney cell lines (HK-2) and subjected to MS/MS for identifying several MA-related proteins, including nucleophosmin, neutral alpha-glucosidase AB, translocon-associated protein subunit alpha, elongation factor 1-gamma, 60S acidic ribosomal protein P0-like, and heat shock protein (HSP 90-alpha and beta). Based on our findings, we believed that the probe can potentially be used to identify and detect the target proteins and help characterize a network of MA protein-protein interactions.

Analysis of protein-protein interactions in MCF-7 and MDA-MB-231 cell lines using phthalic acid chemical probes

Phthalates are a class of plasticizers that have been characterized as endocrine disrupters, and are associated with genital diseases, cardiotoxicity, hepatotoxicity, and nephrotoxicity in the GeneOntology gene/protein database. In this study, we synthesized phthalic acid chemical probes and demonstrated differing protein–protein interactions between MCF-7 cells and MDA-MB-231 breast cancer cell lines. Phthalic acid chemical probes were synthesized using silicon dioxide particle carriers, which were modified using the silanized linker 3-aminopropyl triethoxyslane (APTES). Incubation with cell lysates from breast cancer cell lines revealed interactions between phthalic acid and cellular proteins in MCF-7 and MDA-MB-231 cells. Subsequent proteomics analyses indicated 22 phthalic acid-binding proteins in both cell types, including heat shock cognate 71-kDa protein, ATP synthase subunit beta, and heat shock protein HSP 90-beta. In addition, 21 MCF-7-specific and 32 MDA-MB-231 specific phthalic acid-binding proteins were identified, including related proteasome proteins, heat shock 70-kDa protein, and NADPH dehydrogenase and ribosomal correlated proteins, ras-related proteins, and members of the heat shock protein family, respectively.