Verrucarin A enhances TRAIL-induced apoptosis via NF-κB-mediated Fas overexpression

Trichothecenes from an Endophytic Fungus Alternaria sp. sb23

Three new (alterchothecenes A - C, 1:  -3: ) and 3 known (4:  -6: ) trichothecenes, along with 9 known compounds (7:  -15: ), were isolated from the culture of Alternaria sp. sb23, an endophytic fungus separated from the root of Schisandra sphenanthera Rehd. et Wils. Their structures were elucidated by spectroscopic analyses, and the absolute configurations of 1: -3: were determined through comparison of the experimental electronic circular dichroism (ECD) spectra and optical rotations with similar analogues. In vitro cytotoxicity tests of compounds 1: -6: against human HT-29 colon carcinoma and human MCF-7 breast cancer cell lines indicated that 4: -6: exhibited significant cytotoxic effects, with IC₅₀ values ranging from 0.89 to 9.38 µM. And the potential of compounds 1: -6: as tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) sensitizers in HT-29 cells was evaluated. The results revealed that combination treatment of TRAIL with compounds 1: -6: synergistically decreased cell viability compared with the sole treatment with those compounds.

Establishment and transcriptomic analyses of a cattle rumen epithelial primary cells (REPC) culture by bulk and single-cell RNA sequencing to elucidate interactions of butyrate and rumen development

As a critical and high-value tool to study the development of rumen, we established a stable rumen epithelial primary cell (REPC) culture from a two-week-old Holstein bull calf rumen epithelial tissue. The transcriptomic profiling of the REPC and the direct effects of butyrate on gene expression were assessed. Correlated gene networks elucidated the putative roles and mechanisms of butyrate action in rumen epithelial development. The top networks perturbed by butyrate were associated with epithelial tissue development. Additionally, two critical upstream regulators, E2F1 and TGFB1, were identified to play critical roles in the differentiation, development, and growth of epithelial cells. Significant expression changes of upstream regulators and transcription factors provided further evidence in support that butyrate plays a specific and central role in regulating genomic and epigenomic activities influencing rumen development. This work is the essential component to obtain a complete global landscape of regulatory elements in cattle and to explore the dynamics of chromatin states in rumen epithelial cells induced by butyrate at early developmental stages.

Ginsenoside Rb1, A Major Saponin from Panax ginseng, Exerts Protective Effects Against Acetaminophen-Induced Hepatotoxicity in Mice

Acute liver injury (ALI) induced by acetaminophen (APAP) is the main cause of drug-induced liver injury. Previous reports indicated liver failure could be alleviated by saponins (ginsenosides) from Panax ginseng against APAP-induced inflammatory responses in vivo. However, validation towards ginsenoside Rb1 as a major and marker saponin may protect liver from APAP-induced ALI and its mechanisms are poorly elucidated. In this study, the protective effects and the latent mechanisms of Rb1 action against APAP-induced hepatotoxicity were investigated. Rb1 was administered orally with 10mg/kg and 20mg/kg daily for 1 week before a single injection of APAP (250mg/kg, i.p.) 1h after the last treatment of Rb1. Serum alanine/aspartate aminotransferases (ALT/AST), liver glutathione (GSH) depletion, as well as the inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), were analyzed to indicate the underlying protective effects of Rb1 against APAP-induced hepatotoxicity with significant inflammatory responses. Histological examination further proved Rb1's protective effects. Importantly, Rb1 mitigated the changes in the phosphorylation of MAPK and PI3K/Akt, as well as its downstream factor NF-κB. In conclusion, experimental data clearly demonstrated that Rb1 exhibited a remarkable liver protective effect against APAP-induced ALI, partly through regulating MAPK and PI3K/Akt signaling pathways-mediated inflammatory responses.

Impact of NF-κB pathway on the apoptosis-inflammation-autophagy crosstalk in human degenerative nucleus pulposus cells

The NF-κB pathway has been reported to play a very important role in the process of intervertebral disc degeneration (IVDD). Our results demonstrated that knockdown of NF-κB with P65-siRNA can significantly decrease cell apoptosis and the expression of pro-inflammation factors TNF-α and IL-1β in LPS-induced nucleus pulposus cells (NPCs). However, the molecular mechanism of NF-κB pathway exerting anti-inflammation and anti-apoptosis function remains unclear. Some researchers reported that inhibiting NF-κB pathway can attenuate the catabolic effect by promoting autophagy during inflammatory conditions in rat nucleus pulposus cells. Therefore, we hypothesized that in human NPCs, inhibiting NF-κB pathway may also promote autophagy. Our results indicated that after knockdown of NF-κB, the autophagy was significantly increased and the expression of p-AKT and p-mTOR protein markedly decreased, but the level of autophagy was inhibited after treatment with AKT activator SC79, suggesting the involvement of AKT/mTOR-mediated autophagy was under autophagy activation. However, both LPS-induced NPCs apoptosis and expression of pro-inflammation factors were further increased by pretreatment with the autophagy inhibitor chloroquine (CQ). These suggested that inhibiting NF-κB pathway can promote autophagy and decrease apoptosis and inflammation response in LPS-induced NPCs. Meanwhile, autophagy triggered by NF-κB inhibition plays a protective role against apoptosis and inflammation.

Maltol Improves APAP-Induced Hepatotoxicity by Inhibiting Oxidative Stress and Inflammation Response via NF-κB and PI3K/Akt Signal Pathways

Maltol, a food-flavoring agent and Maillard reaction product formed during the processing of red ginseng (Panax ginseng, C.A. Meyer), has been confirmed to exert a hepatoprotective effect in alcohol-induced oxidative damage in mice. However, its beneficial effects on acetaminophen (APAP)-induced hepatotoxicity and the related molecular mechanisms remain unclear. The purpose of this article was to investigate the protective effect and elucidate the mechanisms of action of maltol on APAP-induced liver injury in vivo. Maltol was administered orally at 50 and 100 mg/kg daily for seven consecutive days, then a single intraperitoneal injection of APAP (250 mg/kg) was performed after the final maltol administration. Liver function, oxidative indices, inflammatory factors—including serum alanine and aspartate aminotransferases (ALT and AST), tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), liver glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), cytochrome P450 E1 (CYP2E1) and 4-hydroxynonenal (4-HNE) were measured. Results demonstrated that maltol possessed a protective effect on APAP-induced liver injury. Liver histological changes and Hoechst 33258 staining also provided strong evidence for the protective effect of maltol. Furthermore, a maltol supplement mitigated APAP-induced inflammatory responses by increasing phosphorylated nuclear factor-kappa B (NF-κB), inhibitor kappa B kinase α/β (IKKα/β), and NF-kappa-B inhibitor alpha (IκBα) in NF-κB signal pathways. Immunoblotting results showed that maltol pretreatment downregulated the protein expression levels of the B-cell-lymphoma-2 (Bcl-2) family and caspase and altered the phosphorylation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) in a dose-dependent manner. In conclusion, our findings clearly demonstrate that maltol exerts a significant liver protection effect, which may partly be ascribed to its anti-inflammatory and anti-apoptotic action via regulation of the PI3K/Akt signaling pathway.

Trichothecenes: immunomodulatory effects, mechanisms, and anti-cancer potential

Paradoxically, trichothecenes have both immunosuppressive and immunostimulatory effects. The underlying mechanisms have not been fully explored. Early studies show that dose, exposure timing, and the time at which immune function is assessed influence whether trichothecenes act in an immunosuppressive or immunostimulatory fashion. Recent studies suggest that the immunomodulatory function of trichothecenes is also actively shaped by competing cell-survival and death-signaling pathways. Autophagy may also promote trichothecene immunosuppression, although the mechanism may be complicated. Moreover, trichothecenes may generate an "immune evasion" milieu that allows pathogens to escape host and vaccine immune defenses. Some trichothecenes, especially macrocyclic trichothecenes, also potently kill cancer cells. T-2 toxin conjugated with anti-cancer monoclonal antibodies significantly suppresses the growth of thymoma EL-4 cells and colon cancer cells. The type B trichothecene diacetoxyscirpenol specifically inhibits the tumor-promoting factor HIF-1 in cancer cells under hypoxic conditions. Trichothecin markedly inhibits the growth of multiple cancer cells with constitutively activated NF-κB. The type D macrocyclic toxin Verrucarin A is also a promising therapeutic candidate for leukemia, breast cancer, prostate cancer, and pancreatic cancer. The anti-cancer activities of trichothecenes have not been comprehensively summarized. Here, we first summarize the data on the immunomodulatory effects of trichothecenes and discuss recent studies that shed light on the underlying cellular and molecular mechanisms. These mechanisms include autophagy and major signaling pathways and their crosstalk. Second, the anti-cancer potential of trichothecenes and the underlying mechanisms will be discussed. We hope that this review will show how trichothecene bioactivities can be exploited to generate therapies against pathogens and cancer.

Kallistatin protects against sepsis-related acute lung injury via inhibiting inflammation and apoptosis

Kallistatin, an endogenous plasma protein, exhibits pleiotropic properties in inhibiting inflammation, oxidative stress and apoptosis, as evidenced in various animal models and cultured cells. Here, we demonstrate that kallistatin levels were positively correlated with the concentration of total protein in bronchoalveolar lavage fluids (BALF) from patients with sepsis-related acute respiratory distress syndrome (ARDS), indicating a compensatory mechanism. Lower ratio of kallistatin to total protein in BALF showed a significant trend toward elevated neutrophil counts (P = 0.002) in BALF and increased mortality (P = 0.046). In lipopolysaccharide (LPS)-treated mice, expression of human kallistatin in lung by gene transfer with human kallistatin-encoding plasmid ameliorated acute lung injury (ALI) and reduced cytokine/chemokine levels in BALF. These mice exhibited attenuated lung epithelial apoptosis and decreased Fas/FasL expression compared to the control mice. Mouse survival was improved by kallistatin gene transfer or recombinant human kallistatin treatment after LPS challenge. In LPS-stimulated A549 human lung epithelial cells, kallistatin attenuated apoptosis, down-regulated Fas/FasL signaling, suppressed intracellular reactive oxygen species (ROS) and inhibited ROS-mediated NF-κB activation and inflammation. Furthermore, LPS-induced apoptosis was blocked by antioxidant N-acetylcysteine or NF-κB inhibitor via down-regulating Fas expression. These findings suggest the therapeutic potential of kallistatin for sepsis-related ALI/ARDS.

Drugs from marine sources: modulation of TRAIL induced apoptosis in cancer cells

There have been overwhelming advances in molecular oncology and data obtained through high-throughput technologies have started to shed light on wide ranging molecular mechanisms that underpin cancer progression. Increasingly it is being realized that marine micro-organisms and the biodiversity of plankton are rich sources of various anticancer compounds. Marine derived compounds play major roles in inducing apoptosis in cancer cells. More importantly, various agents have been noted to enhance TRAIL induced apoptosis in cancer cells by functionalizing intrinsic and extrinsic pathways. In this commentary, a list of marine derived compounds reported to induce apoptosis is discussed.

Identification of verrucarin a as a potent and selective steroid receptor coactivator-3 small molecule inhibitor

Members of the steroid receptor coactivator (SRC) family are overexpressed in numerous types of cancers. In particular, steroid receptor coactivator 3 (SRC-3) has been recognized as a critical coactivator associated with tumor initiation, progression, recurrence, metastasis, and chemoresistance where it interacts with multiple nuclear receptors and other transcription factors to enhance their transcriptional activities and facilitate cross-talk between pathways that stimulate cancer progression. Because of its central role as an integrator of growth signaling pathways, development of small molecule inhibitors (SMIs) against SRCs have the potential to simultaneously disrupt multiple signal transduction networks and transcription factors involved in tumor progression. Here, high-throughput screening was performed to identify compounds able to inhibit the intrinsic transcriptional activities of the three members of the SRC family. Verrucarin A was identified as a SMI that can selectively promote the degradation of the SRC-3 protein, while affecting SRC-1 and SRC-2 to a lesser extent and having no impact on CARM-1 and p300 protein levels. Verrucarin A was cytotoxic toward multiple types of cancer cells at low nanomolar concentrations, but not toward normal liver cells. Moreover, verrucarin A was able to inhibit expression of the SRC-3 target genes MMP2 and MMP13 and attenuated cancer cell migration. We found that verrucarin A effectively sensitized cancer cells to treatment with other anti-cancer drugs. Binding studies revealed that verrucarin A does not bind directly to SRC-3, suggesting that it inhibits SRC-3 through its interaction with an upstream effector. In conclusion, unlike other SRC SMIs characterized by our laboratory that directly bind to SRCs, verrucarin A is a potent and selective SMI that blocks SRC-3 function through an indirect mechanism.