Marti Jett

Growth control of lung cancer by interruption of 5-lipoxygenase-mediated growth factor signaling.

Signal transduction pathways shared by different autocrine growth factors may provide an efficient approach to accomplish clinically significant control of lung cancer growth. In this study, we demonstrate that two autocrine growth factors activate 5-lipoxygenase action of the arachidonic acid metabolic pathway in lung cancer cell lines. Both growth factors increased the production of 5(S)-hydrooxyeicosa-6E,8Z,11Z,14Z-tetraeno ic acid (5-HETE), a major early 5-lipoxygenase metabolic product. Exogenously added 5-HETE stimulated lung cancer cell growth in vitro. Inhibition of 5-lipoxygenase metabolism by selective antagonists resulted in significant growth reduction for a number of lung cancer cell lines. Primary clinical specimens and lung cancer cell lines express the message for the 5-lipoxygenase enzymes responsible for the generation of active metabolites. In vivo evaluation demonstrated that interruption of 5-lipoxygenase signaling resulted in enhanced levels of programmed cell death. These findings demonstrate that 5-lipoxygenase activation is involved with growth factor-mediated growth stimulation for lung cancer cell lines. Pharmacological intervention with lipoxygenase inhibitors may be an important new clinical strategy to regulate growth factor-dependent stages of lung carcinogenesis.

Five-lipoxygenase inhibitors can mediate apoptosis in human breast cancer cell lines through complex eicosanoid interactions.

Many arachidonic acid metabolites function in growth signaling for epithelial cells, and we previously reported the expression of the major arachidonic acid enzymes in human breast cancer cell lines. To evaluate the role of the 5‐lipoxygenase (5‐LO) pathway on breast cancer growth regulation, we exposed cells to insulinlike growth factor‐1 or transferrin, which increased the levels of the 5‐LO metabolite, 5(S)‐hydrooxyeicosa‐6E,8C,11Z,14Z‐tetraenoic acid (5‐HETE), by radioimmunoassay and high‐performance liquid chromatography. Addition of 5‐HETE to breast cancer cells resulted in growth stimulation, whereas selective biochemical inhibitors of 5‐LO reduced the levels of 5‐HETE and related metabolites. Application of 5‐LO or 5‐LO activating protein‐directed inhibitors, but not a cyclooxygenase inhibitor, reduced growth, increased apoptosis, down‐regulated bcl‐2, up‐regulated bax, and increased G1 arrest. Exposure of breast cancer cells to a 5‐LO inhibitor up‐regulated peroxisome proliferator‐activated receptor (PPAR)α and PPARγ expression, and these same cells were growth inhibited when exposed to relevant PPAR agonists. These results suggest that disruption of the 5‐LO signaling pathway mediates growth arrest and apoptosis in breast cancer cells. Additional experiments suggest that this involves the interplay of several factors, including the loss of growth stimulation by 5‐LO products, the induction of PPARγ, and the potential activation of PPARγ by interactions with shunted endoperoxides.

Effect of NASA Light-Emitting Diode Irradiation on Molecular Changes for Wound Healing in Diabetic Mice

OBJECTIVE The purpose of this study was to assess the changes in gene expression of near-infrared light therapy in a model of impaired wound healing. BACKGROUND DATA Light-Emitting Diodes (LED), originally developed for NASA plant growth experiments in space, show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper we present the effects of LED treatment on wounds in a genetically diabetic mouse model. MATERIALS AND METHODS Polyvinyl acetal (PVA) sponges were subcutaneously implanted in the dorsum of BKS.Cg-m +/+ Lepr(db) mice. LED treatments were given once daily, and at the sacrifice day, the sponges, incision line and skin over the sponges were harvested and used for RNA extraction. The RNA was subsequently analyzed by cDNA array. RESULTS Our studies have revealed certain tissue regenerating genes that were significantly upregulated upon LED treatment when compared to the untreated sample. Integrins, laminin, gap junction proteins, and kinesin superfamily motor proteins are some of the genes involved during regeneration process. These are some of the genes that were identified upon gene array experiments with RNA isolated from sponges from the wound site in mouse with LED treatment. CONCLUSION We believe that the use of NASA light-emitting diodes (LED) for light therapy will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the Defense Advanced Research Projects Agency (DARPA) and NASA Marshall Space Flight Center-SBIR Program.

A study of the enterotoxigenicity of coagulase-negative and coagulase-positive staphylococcal isolates from food poisoning outbreaks in Minas Gerais, Brazil

OBJECTIVES The purpose of this study was to identify enterotoxin genes from isolates of coagulase-negative staphylococci and coagulase-positive staphylococci obtained from dairy products, responsible for 16 outbreaks of food poisoning. METHODS From the pool of 152 staphylococcal isolates, 15 coagulase-negative and 15 coagulase-positive representatives were selected for this study. The 15 coagulase-negative isolates were tested for the presence of coa and femA genes, which are known to be characteristic of Staphylococcus aureus. After testing for enterotoxin genes by polymerase chain reaction (PCR), the 30 selected isolates were tested for the presence of toxin by immunoassay. RESULTS Seven of the coagulase-negative isolates amplified the coa gene and were subsequently reclassified as coagulase-positive. Twenty-one of 30 selected isolates had staphylococcal enterotoxin genes and most of these produced toxin as well. The most frequently encountered enterotoxin genes were sea and seb. Among eight coagulase-negative isolates, five had enterotoxin genes, all of which were found to have detectable toxin by immunoassay. CONCLUSIONS The results from this study demonstrate that coagulase-negative as well as coagulase-positive staphylococci isolated from dairy products are capable of genotypic and phenotypic enterotoxigenicity. Furthermore, these data demonstrate that PCR is a sensitive and specific method for screening outbreak isolates regardless of coagulase expression.

Safety, immunogenicity, and efficacy of the ML29 reassortant vaccine for Lassa fever in small non-human primates

A single injection of ML29 reassortant vaccine for Lassa fever induces low, transient viremia, and low or moderate levels of ML29 replication in tissues of common marmosets depending on the dose of the vaccination. The vaccination elicits specific immune responses and completely protects marmosets against fatal disease by induction of sterilizing cell-mediated immunity. DNA array analysis of human peripheral blood mononuclear cells from healthy donors exposed to ML29 revealed that gene expression patterns in ML29-exposed PBMC and control, media-exposed PBMC, clustered together confirming safety profile of the ML29 in non-human primates. The ML29 reassortant is a promising vaccine candidate for Lassa fever.

Identification of a Transcytosis Epitope on Staphylococcal Enterotoxins

ABSTRACT Staphylococcal enterotoxins (SE) are exoproteins produced by Staphylococcus aureus that act as superantigens and have been implicated as a leading cause of food-borne disease and toxic shock. Little is known about how these molecules penetrate the gut lining and gain access to both local and systemic immune tissues. To model movement in vitro of staphylococcal enterotoxins, we have employed a monolayer system composed of crypt-like human colonic T-84 cells. SEB and SEA showed comparable dose-dependent transcytosis in vitro, while toxic shock syndrome toxin (TSST-1) exhibited increased movement at lower doses. Synthetic peptides corresponding to specific regions of the SEB molecule were tested in vitro to identify the domain of the protein involved in the transcytosis of SE. A toxin peptide of particular interest contains the amino acid sequence KKKVTAQELD, which is highly conserved across all SE. At a toxin-to-peptide ratio of 1:10, movement of SEB across the monolayers was reduced by 85%. Antisera made against the SEB peptide recognized native SEB and also inhibited SEB transcytosis. Finally, the conserved 10-amino-acid peptide inhibited transcytosis of multiple staphylococcal enterotoxins, SEA, SEE, and TSST-1. These data demonstrate that this region of the staphylococcal enterotoxins plays a distinct role in toxin movement across epithelial cells. It has implications for the prevention of staphylococcal enterotoxin-mediated disease by design of a peptide vaccine that could reduce systemic exposure to oral or inhaled superantigens. Since the sequence identified is highly conserved, it allows for a single epitope blocking the transcytosis of multiple SE.

Early Blood Profiles of Virus Infection in a Monkey Model for Lassa Fever

ABSTRACT Acute arenavirus disease in primates, like Lassa hemorrhagic fever in humans, begins with flu-like symptoms and leads to death approximately 2 weeks after infection. Our goal was to identify molecular changes in blood that are related to disease progression. Rhesus macaques (Macaca mulatta) infected intravenously with a lethal dose of lymphocytic choriomeningitis virus (LCMV) provide a model for Lassa virus infection of humans. Blood samples taken before and during the course of infection were used to monitor gene expression changes that paralleled disease onset. Changes in blood showed major disruptions in eicosanoid, immune response, and hormone response pathways. Approximately 12% of host genes alter their expression after LCMV infection, and a subset of these genes can discriminate between virulent and nonvirulent LCMV infection. Major transcription changes have been given preliminary confirmation by quantitative PCR and protein studies and will be valuable candidates for future validation as biomarkers for arenavirus disease.

An experimental model system for HIV-1-induced brain injury

The pathological hallmark of HIV infection in brain is productive viral replication in cells of mononuclear phagocyte lineage including brain macrophages, microglia and multinucleated giant cells (Koenig et al., 1986; Wiley et al., 1986; Gabuzda et al., 1986; Stoler et al., 1986). These cells secrete viral and cell encoded neurotoxins that lead to neuronal injury, glial proliferation and myelin pallor during advancing disease (Genis et al., 1992; Giulian et al., 1990, 1993; Pulliam et al., 1991). The apparent paradox between the distribution and numbers of virus infected cells and brain tissue pathology support indirect mechanisms for CNS damage (Epstein, 1993; Geleziunas et al., 1992; Merrill and Chen, 1992; Michaels et al., 1988; Price et al., 1988). First, brain macrophages and microglia can produce neurotoxins by secretion of viral proteins (for example, gp120) (Dawson et al., 1991; Merrill et al., 1989; Lipton et al., 1990; Lipton, 1993). Second, HIV primes macrophages for immune activation to produce neurotoxins including: cytokines (TNF alpha and IL-1 beta), eicosanoids: quinolinate and nitric oxide (NO). Chronic immune stimulation mediated by opportunistic infections and chronic interferon gamma (IFN gamma) production (in and outside the CNS) continues the process of macrophage activation leading to progressive neural injury. The hyperresponsiveness of HIV-infected macrophages to activation results in production of cellular factors that activate uninfected macrophages. This suggests that HIV-infected macrophages are both perpetrators and amplifiers for neurotoxic activities.

Control of the growth of human breast cancer cells in culture by manipulation of arachidonate metabolism.

BackgroundArachidonate metabolites are important regulators of human breast cancer cells. Production of bioactive lipids are frequently initiated by the enzyme phospholipase A2 which releases arachidonic acid (AA) that is rapidly metabolized by cyclooxygenases (COX) or lipoxygenases (LO) to other highly potent lipids.MethodsIn this study we screened a number of inhibitors which blocked specific pathways of AA metabolism for their antiproliferative activity on MCF-7 wild type and MCF-7 ADR drug resistant breast cancer cells. The toxicity of these inhibitors was further tested on human bone marrow cell proliferation.ResultsInhibitors of LO pathways (specifically the 5-LO pathway) were most effective in blocking proliferation. Inhibitors of platelet activating factor, a byproduct of arachidonate release, were also effective antiproliferative agents. Curcumin, an inhibitor of both COX and LO pathways of eicosanoid metabolism, was 12-fold more effective in blocking proliferation of the MCF-7 ADRs cells compared to MCF-7 wild type (WT) cells. These inhibitors that effectively blocked the proliferation of breast cancer cells showed varying degrees of toxicity to cultures of human bone marrow cells. We observed greater toxicity to bone marrow cells with inhibitors that interfere with the utilization of AA in contrast to those which block utilization of its downstream metabolites. MK-591, MK-886, PCA-4248, and AA-861 blocked proliferation of breast cancer cells but showed no toxicity to bone marrow cells.ConclusionThese inhibitors were effective in blocking the proliferation of breast cancer cells and may be potentially useful in human breast cancer therapy.

A genome-wide identified risk variant for PTSD is a methylation quantitative trait locus and confers decreased cortical activation to fearful faces

Genetic factors appear to be highly relevant to predicting differential risk for the development of post‐traumatic stress disorder (PTSD). In a discovery sample, we conducted a genome‐wide association study (GWAS) for PTSD using a small military cohort (Systems Biology PTSD Biomarkers Consortium; SBPBC, N = 147) that was designed as a case‐controlled sample of highly exposed, recently returning veterans with and without combat‐related PTSD. A genome‐wide significant single nucleotide polymorphism (SNP), rs717947, at chromosome 4p15 (N = 147, β = 31.34, P = 1.28 × 10−8) was found to associate with the gold‐standard diagnostic measure for PTSD (the Clinician Administered PTSD Scale). We conducted replication and follow‐up studies in an external sample, a larger urban community cohort (Grady Trauma Project, GTP, N = 2006), to determine the robustness and putative functionality of this risk variant. In the GTP replication sample, SNP rs717947 associated with PTSD diagnosis in females (N = 2006, P = 0.005), but not males. SNP rs717947 was also found to be a methylation quantitative trait locus (meQTL) in the GTP replication sample (N = 157, P = 0.002). Further, the risk allele of rs717947 was associated with decreased medial and dorsolateral cortical activation to fearful faces (N = 53, P < 0.05) in the GTP replication sample. These data identify a genome‐wide significant polymorphism conferring risk for PTSD, which was associated with differential epigenetic regulation and with differential cortical responses to fear in a replication sample. These results may provide new insight into understanding genetic and epigenetic regulation of PTSD and intermediate phenotypes that contribute to this disorder.