piplartine and Necrosis

Excessive necroptosis contributes to the pathogenesis of several inflammatory and neurodegenerative diseases. Here, using a high-throughput screening approach, we investigated the anti-necroptosis effects of piperlongumine, an alkaloid isolated from the long pepper plant, in vitro and in a mouse model of systemic inflammatory response syndrome (SIRS).. A natural compound library was screened for anti-necroptosis effects in cellular. The underlying mechanism of action of the top candidate piperlongumine was explored by quantifying the necroptosis marker phosphorylated receptor-interacting protein kinase 1 (p-RIPK1) by Western blotting. The anti-inflammatory effect of piperlongumine was assessed in a tumor necrosis factor α (TNFα)-induced SIRS model in mice.. Among the compounds investigated, piperlongumine significantly rescued cell viability. The half maximal effective concentration (EC. As a potent necroptosis inhibitor, piperlongumine prevents phosphorylation of RIPK1 at its activation residue Ser166. Piperlongumine thus potently inhibits necroptosis at concentrations safe enough for human cells in vitro and inhibits TNFα-induced SIRS in mice. Piperlongumine has potential clinical translational value for the treatment of the spectrum of diseases associated with necroptosis, including SIRS.

Topics: Animals; Apoptosis; Humans; Mice; Necrosis; Systemic Inflammatory Response Syndrome; Tumor Necrosis Factor-alpha

Piperlongumine (PL), a natural product isolated from the plant species Piper longum L., can selectively induce apoptotic cell death in cancer cells by targeting the stress response to reactive oxygen species (ROS). Here we show that PL induces cell death in the presence of benzyloxycarbonylvalyl-alanyl-aspartic acid (O-methyl)-fluoro-methylketone (zVAD-fmk), a pan-apoptotic inhibitor, and in the presence of necrostatin-1, a necrotic inhibitor. Instead PL-induced cell death can be suppressed by 3-methyladenine, an autophagy inhibitor, and substantially attenuated in cells lacking the autophagy-related 5 (Atg5) gene. We further show that PL enhances autophagy activity without blocking autophagy flux. Application of N-acetyl-cysteine, an antioxidant, markedly reduces PL-induced autophagy and cell death, suggesting an essential role for intracellular ROS in PL-induced autophagy. Furthermore, PL stimulates the activation of p38 protein kinase through ROS-induced stress response and p38 signaling is necessary for the action of PL as SB203580, a p38 inhibitor, or dominant-negative p38 can effectively reduce PL-mediated autophagy. Thus, we have characterized a new mechanism for PL-induced cell death through the ROS-p38 pathway. Our findings support the therapeutic potential of PL by triggering autophagic cell death.

Topics: Animals; Apoptosis; Autophagy; Cell Line; Dioxolanes; Energy Metabolism; Homeostasis; Humans; Intracellular Space; MAP Kinase Signaling System; Mice; Necrosis; p38 Mitogen-Activated Protein Kinases; Phagosomes; Reactive Oxygen Species

Piplartine {5,6-dihydro-1-[1-oxo-3-(3,4,5-trimethoxyphenyl)-2-propenyl]-2(1H)pyridinone} is an alkaloid/amide component of Piper species. The purpose of the present study was to examine the antiproliferative effects of piplartine on human leukemia cell lines HL-60, K562, Jukart, and Molt-4 using the trypan blue exclusion method, as well as the effect of piplartine on DNA synthesis. The viability of all human leukemia cell lines were not affected by piplartine after 6 h, 9 h, and 12 h exposure, whereas a steady decline was seen after an exposure time of 24 h. The antiproliferative activity of piplartine seemed to be related to the inhibition of DNA synthesis, as revealed by the reduction of 5-bromo-2'-deoxyuridine (BrdU) incorporation after 24h of incubation. Piplartine-mediated reduction in cell number was associated with an increasing number of dead cells at a concentration of 10 microg/ml. These findings were corroborated by morphologic analysis. However, at the lowest concentration (2.5 microg/ml), piplartine-treated cells exhibited typical apoptotic morphological changes. The increase in caspase-3 activity was also observed in lysates of piplartine-treated cells (2.5 microg/ml). Our findings suggest that piplartine can suppress leukemia growth and reduce cell survival, triggering both apoptosis and/or necrosis, depending on the concentration used.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cell Survival; DNA; DNA, Neoplasm; Dose-Response Relationship, Drug; Enzyme Activation; HL-60 Cells; Humans; In Vitro Techniques; K562 Cells; Leukemia; Leukemia, T-Cell; Microscopy, Fluorescence; Monocytes; Necrosis; Nucleic Acid Conformation; Piper; Piperidones; Signal Transduction