Effect of high-frequency low-intensity pulsed electric field on protecting SH-SY5Y cells against hydrogen peroxide and ß-amyloid-induced cell injury via ERK pathway.

As the most common type of neurodegenerative diseases (NDDs), Alzheimer's disease (AD) is thought to be caused mainly by the excessive aggregation of ß-amyloid protein (Aß). However, a growing number of studies have found that reactive oxygen species (ROS) play a key role in the onset and progression of AD. The present study aimed to probe the neuroprotective effect of high-frequency low-intensity pulsed electric field (H-LIPEF) for SH-SY5Y cells against hydrogen peroxide (H2O2) and Aß-induced cytotoxicity. By looking in a systematic way into the frequency- and amplitude-dependent neuroprotective effect of pulsed electric field (PEF), the study finds that H-LIPEF at 200 Hz produces the optimal protective effect for SH-SY5Y cells. The underlying mechanisms were confirmed to be due to the activation of extracellular signal-regulated kinase (ERK) pathway and the downstream prosurvival and antioxidant proteins. Because the electric field can be modified to focus on specific area in a non-contact manner, the study suggests that H-LIPEF holds great potential for treating NDDs, whose effect can be further augmented with the administering of drugs or natural compounds at the same time.

Thermal cycling protects SH-SY5Y cells against hydrogen peroxide and ß-amyloid-induced cell injury through stress response mechanisms involving Akt pathway.

Neurodegenerative diseases (NDDs) are becoming a major threat to public health, according to the World Health Organization (WHO). The most common form of NDDs is Alzheimer's disease (AD), boasting 60-70% share. Although some debates still exist, excessive aggregation of ß-amyloid protein (Aß) and neurofibrillary tangles has been deemed one of the major causes for the pathogenesis of AD. A growing number of evidences from studies, however, have suggested that reactive oxygen species (ROS) also play a key role in the onset and progression of AD. Although scientists have had some understanding of the pathogenesis of AD, the disease still cannot be cured, with existing treatment only capable of providing a temporary relief at best, partly due to the obstacle of blood-brain barrier (BBB). The study was aimed to ascertain the neuroprotective effect of thermal cycle hyperthermia (TC-HT) against hydrogen peroxide (H2O2) and Aß-induced cytotoxicity in SH-SY5Y cells. Treating cells with this physical stimulation beforehand significantly improved the cell viability and decreased the ROS content. The underlying mechanisms may be due to the activation of Akt pathway and the downstream antioxidant and prosurvival proteins. The findings manifest significant potential of TC-HT in neuroprotection, via inhibition of oxidative stress and cell apoptosis. It is believed that coupled with the use of drugs or natural compounds, this methodology can be even more effective in treating NDDs.

Thermal cycling as a novel thermal therapy to synergistically enhance the anticancer effect of propolis on PANC­1 cells.

Hyperthermia (HT) has shown potential in cancer therapy. In particular, it appears to sensitize cancer cells to chemotherapy. However, a major concern associated with HT is that the thermal dosage applied to the tumor cells may also harm the normal tissue cells. Besides, the drugs used in HT are conventional chemotherapy drugs, which may cause serious side effects. The present study demonstrated a novel methodology in HT therapy called thermal cycle (TC)­HT. With this strategy, a therapeutic window with a maximum synergistic effect was created by combining TC­HT with natural compounds, with minimal unwanted cell damage. The natural compound propolis was selected, and the synergistic anticancer effect of TC­HT and propolis was investigated in pancreatic cancer cells. The present results demonstrated for the first time that TC­HT could enhance the anticancer effect of propolis on PANC­1 cancer cells through the mitochondria­dependent apoptosis pathway and cell cycle arrest. Combined treatment greatly suppressed mitochondrial membrane potential, which is an important indicator of damaged and dysfunctional mitochondria. Furthermore, the cell cycle­regulating protein cell division cycle protein 2 was downregulated upon combined treatment, which prevented cellular progression into mitosis. The present study offers the first report, to the best of our knowledge, on the combination of TC­HT with a natural compound for pancreatic cancer treatment. It is anticipated that this methodology may be a starting point for more sophisticated cancer treatments and may thereby improve the quality of life of many patients with cancer.

Molecular evolution of cystine-stabilized miniproteins as stable proteinaceous binders.

Small cystine-stabilized proteins are desirable scaffolds for therapeutics and diagnostics. Specific folding and binding properties of the proteinaceous binders can be engineered with combinatorial protein libraries in connection with artificial molecular evolution. The combinatorial protein libraries are composed of scaffold variants with random sequence variation, which inevitably produces a portion of the library sequences incompatible with the parent structure. Here, we used artificial molecular evolution to elucidate structure-determining residues in a smallest cystine-stabilized scaffold. The structural determinant information was then applied to designing cystine-stabilized miniproteins binding to human vascular endothelial growth factor. This work demonstrated a general methodology on engineering artificial cystine-stabilized proteins as antibody mimetics with simultaneously enhanced folding and binding properties.

[Non-apoptotic programmed cell death induced by extract of Spatholobus suberctus in human lung cancer A549 cells].

OBJECTIVE: The goal of study is to explore the cytotoxic activity and its underlying mechanisms of the extract of Spatholobus suberctus in human lung cancer A549 cells. METHOD: The inhibitory effects of the extract on proliferation of human lung cancer cell line A549 was measured by MTT cell viability assay and growth curve. Cell cycle was analyzed using flow cytometry. Apoptotic morphological changes was observed by HE staining technique and AO/PI double-staining confocal laser scanning microscope (CLSM). Employing agarose gel electrophoresis and Annexin V-PI assay, we examed the presence of cytoplasmic histone-associated DNA fragments, and membrane phosphatidylserine (PS) externalization as well as caspase-3 activation. RESULT: The extract of S. suberctus shows strong cytotoxic power on A549 cells during 24 hours and IC50 is 25.54 mg x L(-1). The cells in S-phase increase while the cells in G0-G1 and G2-M decrease. These changes recovered after 48 hours. The nucleus became pyknosis between 8 to 12 hours and many vacuoles and granules in cytoplasm can be seen. Membrane phosphatidylserine externalization occurs in a dose-dependent and time-dependent manner afer 12 hours. Caspase-3 activity has no more changes in a converse dose-dependent manner. No cytoplasmic histone-associated DNA fragments was detected by agarose gel electrophoresis. CONCLUSION: The extract of S. suberctus shows a direct anti-tumor activity. The drug acts quickly and causes S delay in one cell cycle. The main cell death feature appears to be non-apoptotic programmed cell death.

Factor Xa active site substrate specificity with substrate phage display and computational molecular modeling.

Structural origin of substrate-enzyme recognition remains incompletely understood. In the model enzyme system of serine protease, canonical anti-parallel beta-structure substrate-enzyme complex is the predominant hypothesis for the substrate-enzyme interaction at the atomic level. We used factor Xa (fXa), a key serine protease of the coagulation system, as a model enzyme to test the canonical conformation hypothesis. More than 160 fXa-cleavable substrate phage variants were experimentally selected from three designed substrate phage display libraries. These substrate phage variants were sequenced and their specificities to the model enzyme were quantified with quantitative enzyme-linked immunosorbent assay for substrate phage-enzyme reaction kinetics. At least three substrate-enzyme recognition modes emerged from the experimental data as necessary to account for the sequence-dependent specificity of the model enzyme. Computational molecular models were constructed, with both energetics and pharmacophore criteria, for the substrate-enzyme complexes of several of the representative substrate peptide sequences. In contrast to the canonical conformation hypothesis, the binding modes of the substrates to the model enzyme varied according to the substrate peptide sequence, indicating that an ensemble of binding modes underlay the observed specificity of the model serine protease.