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Hepatocellular carcinoma (HCC) is a leading cause of death, resulting in over 700 thousand deaths annually worldwide. Chemotherapy is the primary therapeutic strategy for patients with late-stage HCC. Heteronemin is a marine natural product isolated from Hippospongia sp. that has been found to protect against carcinogenesis in cholangiocarcinoma, prostate cancer, and acute myeloid leukemia. In this study, heteronemin was found to inhibit the proliferation of the HCC cell lines HA22T and HA59T and induce apoptosis via the caspase pathway. Heteronemin treatment also induced the formation of reactive oxygen species (ROS), which are associated with heteronemin-induced cell death, and to trigger ROS removal by mitochondrial SOD2 rather than cytosolic SOD1. The mitogen-activated protein kinase (MAPK) signaling pathway was associated with ROS-induced cell death, and heteronemin downregulated the expression of ERK, a MAPK that is associated with cell proliferation. Inhibitors of JNK and p38, which are MAPKs associated with apoptosis, restored heteronemin-induced cell death. In addition, heteronemin treatment reduced the expression of GPX4, a protein that inhibits ferroptosis, which is a novel form of nonapoptotic programmed cell death. Ferroptosis inhibitor treatment also restored heteronemin-induced cell death. Thus, with appropriate structural modification, heteronemin can act as a potent therapeutic against HCC.

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SummaryThe Zap1 transcription factor is a central player in zinc homeostasis in yeast. This protein regulates the expression of genes involved in zinc accumulation and storage. For most of its target genes, Zap1 activates expression in zinc-limited cells and this function is inhibited in replete cells. Zap1 has two activation domains, AD1 and AD2, which are independently regulated by zinc status. In this study, we characterized AD1 and its regulation by zinc. AD1 was mapped using deletions to residues 332-402 of Zap1. The region required for the zinc responsiveness of this activation domain, designated 'ZRD AD1, was mapped to residues 182-502. Thus, AD1 is embedded within its larger zinc-responsive domain. Using a combination of in silico analysis, random mutagenesis and site-directed mutagenesis, we identified key residues within ZRD AD1 required for its regulation by zinc. Most of these residues are cysteines and histidines that could potentially serve as Zn(II) ligands. These results suggest that ZRD AD1 senses zinc by direct Zn(II) binding. Consistent with this hypothesis, purified ZRD AD1 bound multiple Zn(II) ions. Finally, our results indicate that, in the context of the full-length Zap1 protein, AD1 and AD2 are both critical to the full control of gene expression in response to zinc.

Propofol is one of the most widely used intravenous anesthetics. However, repeated exposure to propofol may cause neurodegeneration in the developing brain. Dexmedetomidine (Dex), an α2 adrenoceptor agonist, has been previously demonstrated to provide neuroprotection against neuroapoptosis and neurocognitive impairments induced by several anesthetics. Thus, the current study aimed to investigate the effect of Dex on neonatal propofol-induced neuroapoptosis and juvenile spatial learning/memory deficits. Propofol (30 mg/kg) was intraperiotoneally administered to 7-day-old Sprague Dawley rats (n=75) three times each day at 90 min intervals for seven consecutive days with or without Dex (75 µg/kg) treatment 20 min prior to propofol injection. Following repeated propofol exposure, reduced Akt and GSK-3β phosphorylation, increased cleaved caspase-3 expression levels, an increased Bax/Bcl-2 ratio, and increased terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells in the CA1 hippocampal subregion were observed. Morris Water Maze testing at postnatal day 29 also demonstrated spatial learning and memory deficits following propofol treatment compared with the control group. Notably, these changes were significantly attenuated by Dex pretreatment. The results of the current study demonstrated that Dex ameliorates the neurocognitive impairment induced by repeated neonatal propofol challenge in rats, partially via its anti-apoptotic action and normalization of the disruption to the PI3K/Akt/GSK-3β signaling pathway. The present study provides preliminary evidence demonstrating the safety of propofol on the neonatal brain and the potential use of dexmedetomidine pretreatment in pediatric patients.

The anticancer effects of ceramide have been reported in many types of cancers but less in lung cancer. In this study, we used C2-ceramide to further investigate its possible anticancer effects and mechanisms on non-small cell lung cancer (NSCLC) H1299 cells. The result of cell proliferation in terms of trypan blue assay showed high dose of C2-ceramide inhibited cell survival after 24 h treatment. The flow cytometry-based assays indicated the effect of apoptosis, chromatin condensation, and G1 arrest in terms of Annexin V/propidium iodide (PI), DAPI, and PI stainings, respectively. Moreover, the decreased protein level of p-Akt, p-NFκB, survivin and cyclin A2 were detected by Western blot assay. Taken together, these results indicated the antiproliferative effect of C2-ceramide is majorly responsible for cell apoptosis in lung cancer H1299 cells.

Soft corals-derived natural product, sinularin, was antiproliferative against some cancers but its effect and detailed mechanism on oral cancer cells remain unclear. The subject of this study is to examine the antioral cancer effects and underlying detailed mechanisms in terms of cell viability, oxidative stress, cell cycle analysis, and apoptosis analyses. In MTS assay, sinularin dose-responsively decreased cell viability of three oral cancer cells (Ca9-22, HSC-3, and CAL 27) but only little damage to oral normal cells (HGF-1). This cell killing effect was rescued by the antioxidant N-acetylcysteine (NAC) pretreatment. Abnormal cell morphology and induction of reactive oxygen species (ROS) were found in sinularin-treated oral cancer Ca9-22 cells, however, NAC pretreatment also recovered these changes. Sinularin arrested the Ca9-22 cells at G2/M phase and dysregulated the G2/M regulatory proteins such as cdc2 and cyclin B1. Sinularin dose-responsively induced apoptosis on Ca9-22 cells in terms of flow cytometry (annexin V and pancaspase analyses) and western blotting (caspases 3, 8, 9) and poly (ADP-ribose) polymerase (PARP). These apoptotic changes of sinularin-treated Ca9-22 cells were rescued by NAC pretreatment. Taken together, sinularin induces oxidative stress-mediated antiproliferation, G2/M arrest, and apoptosis against oral cancer cells and may be a potential marine drug for antioral cancer therapy.

A suitable small animal model may help in the screening and evaluation of new drugs, especially those from natural products, which can be administered at lower dosages, fulfilling an urgent worldwide need. In this study, we explore whether zebrafish could be a model organism for carrageenan-induced abdominal edema. The research results showed that intraperitoneal (i.p.) administration of 1.5% λ-carrageenan in a volume of 20 µL significantly increased abdominal edema in adult zebrafish. Levels of the proinflammatory proteins tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) were increased in carrageenan-injected adult zebrafish during the development of abdominal edema. An associated enhancement was also observed in the leukocyte marker, myeloperoxidase (MPO). To support these results, we further observed that i.p. methylprednisolone (MP; 1 µg), a positive control, significantly inhibited carrageenan-induced inflammation 24 h after carrageenan administration. Furthermore, i.p. pretreatment with either an anti-TNF-α antibody (1∶5 dilution in a volume of 20 µL) or the iNOS-selective inhibitor aminoguanidine (AG; 1 µg) inhibited carrageenan-induced abdominal edema in adult zebrafish. This new animal model is uncomplicated, easy to develop, and involves a straightforward inducement of inflammatory edema for the evaluation of small volumes of drugs or test compounds.