Overexpression of antimicrobial peptides contributes to aging through cytotoxic effects in Drosophila tissues.

The innate immune response tends to become hyperactive and proinflammatory in older organisms. We investigated connections between activity of the immune-related genes and aging using the Drosophila model. A hallmark of Drosophila immunity is the production of antimicrobial peptides (AMP), whose expression is triggered via activation of the Toll and Imd immune pathways and regulated by NF-ĸB-like transcription factors, Dif/Dorsal and Relish. It was previously shown that overexpression of the upstream component of the immune pathways shortens lifespan via activation of the Relish-dependent immune response. Here we show that direct overexpression of the Relish target AMP genes broadly at high levels or in the fat body induced apoptosis, elicited depolarization of the mitochondria and significantly shortened lifespan. Underexpression of Relish in the fat body beginning in the second half of lifespan prevented overactivation of AMPs and extended longevity. Unlike infection-induced responses, the age-related increase in AMPs does not require the upstream recognition/transduction module of the Imd pathway. It does however require downstream elements, including Relish and Ird5, a component of the downstream IKK complex. Together, these results established causal links between high-level production of antimicrobial peptides and longevity.

Mitochondrial peroxiredoxins are essential in regulating the relationship between Drosophila immunity and aging.

Previously, we have shown that flies under-expressing the two mitochondrial peroxiredoxins (Prxs), dPrx3 and dPrx5, display increases in tissue-specific apoptosis and dramatically shortened life span, associated with a redox crisis, manifested as changes in GSH:GSSG and accumulation of protein mixed disulfides. To identify specific pathways responsible for the observed biological effects, we performed a transcriptome analysis. Functional clustering revealed a prominent group enriched for immunity-related genes, including a considerable number of NF-kB-dependent antimicrobial peptides (AMP) that are up-regulated in the Prx double mutant. Using qRT-PCR analysis we determined that the age-dependent changes in AMP levels in mutant flies were similar to those observed in controls when scaled to percentage of life span. To further clarify the role of Prx-dependent mitochondrial signaling, we expressed different forms of dPrx5, which unlike the uniquely mitochondrial dPrx3 is found in multiple subcellular compartments, including mitochondrion, nucleus and cytosol. Ectopic expression of dPrx5 in mitochondria but not nucleus or cytosol partially extended longevity under normal or oxidative stress conditions while complete restoration of life span occurred when all three forms of dPrx5 were expressed from the wild type dPrx5 transgene. When dPrx5 was expressed in mitochondria or in all three compartments, it substantially delayed the development of hyperactive immunity while expression of cytosolic or nuclear forms had no effect on the immune phenotype. The data suggest a critical role of mitochondria in development of chronic activation of the immune response triggered by impaired redox control.

Peroxiredoxins Play an Important Role in the Regulation of Immunity and Aging in Drosophila.

Aberrant immune responses and chronic inflammation can impose significant health risks and promote premature aging. Pro-inflammatory responses are largely mediated via reactive oxygen species (ROS) and reduction-oxidation reactions. A pivotal role in maintaining cellular redox homeostasis and the proper control of redox-sensitive signaling belongs to a family of antioxidant and redox-regulating thiol-related peroxidases designated as peroxiredoxins (Prx). Our recent studies in Drosophila have shown that Prxs play a critical role in aging and immunity. We identified two important 'hubs', the endoplasmic reticulum (ER) and mitochondria, where extracellular and intracellular stress signals are transformed into pro-inflammatory responses that are modulated by the activity of the Prxs residing in these cellular organelles. Here, we found that mitochondrial Prx activity in the intestinal epithelium is required to prevent the development of intestinal barrier dysfunction, which can drive systemic inflammation and premature aging. Using a redox-negative mutant, we demonstrated that Prx acts in a redox-dependent manner in regulating the age-related immune response. The hyperactive immune response observed in flies under-expressing mitochondrial Prxs is due to a response to abiotic signals but not to changes in the bacterial content. This hyperactive response, but not reduced lifespan phenotype, can be rescued by the ER-localized Prx.

Establishment, characterization, and drug sensitivity of a new Ewing sarcoma cell line (SS-ES-1).

Ewing sarcoma (ES) is one of the most malignant tumors in children and young adults. We present here a new ES cell line, SS-ES-1, established from the left thoracic tumor of a 16-year-old female patient. The SS-ES-1 cells retained genotype, morphology, and growth rate for over 150 passages. Immunocytochemical staining showed the strong immunoreactivity for cytokeratin, epithelial membrane antigen, neurofilament, CD99, P53, Ki-67, platelet-derived growth factor receptor-ß, estrogen receptor-α (ER-α), and Bcl-2, but no reactivity for glial fibrillary acidic protein, epidermal growth factor receptor, and HER-2/neu. The presence of the type 1 EWS/FLI-1 fusion transcripts was confirmed by reverse transcriptase-polymerase chain reaction. On the basis of the MTT assay results, GW2974, a dual inhibitor of epidermal growth factor receptor and HER-2/neu, exhibited only a weak cytotoxic response in SS-ES-1 cells. In contrast, tyrphostin A9, a specific inhibitor of platelet-derived growth factor receptor, had a high cytotoxic effect against these cells. Surprisingly, it was found that SS-ES-1 cells displayed a high sensitivity to 4OH-tamoxifen. In conclusion, the SS-ES-1 cell line shows unique cellular properties, which makes it a useful model for studying various aspects of the biology of ES. In addition, the results suggest that ER can be a good therapeutic target for ER + ES.

Diclofenac inhibits proliferation but not NGF-induced differentiation of PC12 cells.

Diclofenac is a non-steroidal anti-inflammatory drug that is prescribed for treatment of rheumatic diseases and as an analgesic. Although the information about these side effects has been widely reported, little is know about the effect of diclofenac on the neural cells. In this study, we investigated the effects of diclofenac on the proliferation and differentiation of PC12 cells. The cell proliferation was evaluated by using XTT assay in the both free-serum neurobasal medium supplemented with B27 supplement and DMEM/F12 medium containing 10% FBS. The nerve growth factor (NGF)-induced differentiation was assessed by measuring the neurite length. The drug toxicity was exhibited at the concentrations more than 310 microM in the supplemented neurobasal medium. The treatment of cells in the DMEM/F12 medium increased their sensitivity to diclofenac, with 40% and 75% growth inhibition at the 155 and 310 microM concentrations, respectively. The NGF-induced differentiation was not reduced by toxic and subtoxic concentrations of diclofenac. The results of this study indicated that diclofenac may be able to exhibit its neurotoxic effects through growth inhibition, but not differentiation inhibition. Supplement of B27 has several antioxidant compounds. Therefore, the difference of diclofenac cytotoxic effects in two culture media suggest that drug cytotoxicity may be related to the oxidative stress.

Modulatory effect of semelil (ANGIPARS™) on isoproterenol induced cardiac injury.

Administration of semelil (ANGIPARS™) has been successful in the treatment of diabetic foot ulcer. Considering the improvement of blood flow and anti-inflammatory effect that are attributed to this drug, we investigated its effect on cardiovascular performance in rabbits with isoproterenol (ISO) induced myocardial injury. Animal groups included: control group; ISO group, received ISO 50 mg/kg s.c. for two consecutive days; S1+ISO, S5+ISO and S10+ISO groups, received semelil 1, 5, and 10 mg/kg/day i.p. respectively, 30 min before ISO. On the 3(rd) day, electrocardiogram (ECG) and hemodynamic parameters were recorded; blood samples were taken and hearts were removed for lab investigations. ISO induced heart injury, ECG disturbance, raise of cardiac troponin I and significant decrease in LVSP (p<0.05), +dp/dt max (p<0.01), -dp/dt max (p<0.05) along with increase of LVEDP (p<0.01). Semelil had no significant effects on ECG and plasma cardiac troponin I. Impairment of +dp/dt max and -dp/dt max was significantly improved in S5+ISO and S10+ISO groups (P<0.05 versus ISO). In addition, LVSP and LVEDP was somewhat recovered in these groups, although semelil (1 mg/kg/day) to some extent exacerbated the myocardial lesions induced by ISO (P<0.05). Therefore, in stressful conditions, semelil may improve myocardial contractility; however, it may aggravate the severity of injury.

N-Substituted piperazinyl quinolones as potential cytotoxic agents: structure-activity relationships study.

As part of a continuing search for new potential anticancer candidates in the piperazinyl quinolone series, the cytotoxicity evaluation of new N-substituted piperazinyl quinolones was of our interest. The growth inhibitory activities of 12 new compounds, namely N-[2-(5-chlorothiophen-2-yl)-2-oxoethyl] and N-[2-(5-chlorothiophen-2-yl)-2-oxyiminoethyl] piperazinyl quinolones 1-12 were determined against six cancer cell lines using MTT colorimetric assay. Preliminary screening showed that most of the new N-[2-(5-chlorothiophen-2-yl)ethyl]piperazinyl quinolones 4-12 containing (un)substituted oxime moiety showed significant cytotoxic activity and the modification of functionality on ethyl spacer produced a relatively minor change of activity. Thus, in the piperazinyl quinolone series, cytotoxic activity can be positively modulated through the introduction of 2-(5-chlorothiophen-2-yl)ethyl residue on the piperazine ring. The results revealed that the introduction of 2-(5-chlorothiophen-2-yl)ethyl moiety on the piperazine ring of quinolone antibacterials (ciprofloxacin, norfloxacin and enoxacin) changes the biological profile of piperazinyl quinolones from antibacterials to cytotoxic agents.