A novel sesquiterpene lactone fraction from Eupatorium chinense L. suppresses hepatocellular carcinoma growth by triggering ferritinophagy and mitochondrial damage

BACKGROUND

Hepatocellular carcinoma (HCC) is an aggressive tumor with limited treatment options, and it is the third leading cause of cancer-related deaths. Hence, novel therapeutic strategies are required to treat HCC. Eupatorium chinense L. is a traditional Chinese medicine (TCM) that can effectively neutralize heat and smoothen the flow of "Qi" through the liver. However, the anti-HCC effects of Eupatorium chinense L. remain unknown.

PURPOSE

The present study investigated the anti-HCC effects and the underlying mechanisms of the electrophilic sesquiterpenes isolated from E. chinense L. (EChLESs) in the regulation of ferroptosis and apoptosis in HCC cells.

STUDY DESIGN/METHODS

Cell viability was assessed by the MTT assay. Cell apoptosis was confirmed by flow cytometry and western blotting assay. Ferroptosis was assessed by flow cytometry, transmission electron microscopy, and western blotting assay. Ferritinophagy was detected by acridine orange staining and western blotting assay. Small interfering RNA of nuclear receptor coactivator 4 (NCOA4) was used to confirm the role of ferritinophagy in the therapeutic effect of EChLESs on HCC cells. A mouse xenograft model was constructed to determine the inhibitory effect of EChLESs on HCC in vivo.

RESULTS

EChLESs induced apoptosis by disrupting mitochondrial membrane potential depolarization and mitochondrial reactive oxygen species. EChLESs induced ferroptosis as noted by a significant increase in mitochondrial disruption, lipid peroxidation, and intracellular iron level and decreased glutathione level. The apoptosis inhibitor Z-VAD-FMK and lipid reactive oxygen species scavenger ferrostatin 1 attenuated EChLESs-induced cell death. NCOA4-mediated ferritinophagy through autophagic flux was the crucial pathway for ferroptosis induced by EChLESs. NCOA4 knockdown alleviated EChLESs-induced cell death. EChLESs controlled the expression of NCOA4 at the transcriptional and post-transcriptional levels. In the in vivo experiment, EChLESs suppressed HCC growth in the xenograft tumor mouse model.

CONCLUSION

EChLESs enhances cell apoptosis through mitochondrial dysfunction and ferroptosis through NCOA4-mediated ferritinophagy. Thus, Eupatorium chinense L. could be a potential TCM for treating HCC.

Effect of dietary Bacillus subtilis on proportion of Bacteroidetes and Firmicutes in swine intestine and lipid metabolism

The ratio of Bacteroidetes and Firmicutes bacterial groups in the gut can affect the ability to absorb nutrients. We investigated the effect of probiotic Bacillus subtilis supplementation of diets on growth performance, fat deposition, blood lipids, copy numbers, and percentage of Bacteroidetes and Firmicutes in cecal contents, as well as mRNA expression of key lipid metabolism enzymes in the liver and adipose tissue of finishing pigs. Twenty-four Duroc x Meishan crossbreed 8-week-old pigs (10.28 ± 0.59 kg) were randomly allocated to two dietary treatments: maize-soybean meal-based diets with B. subtilis (probiotic group) and without B. subtilis (control group). The probiotic diet led to a significant increase in the average daily gain and feed conversion ratio of pigs weighing 10 to 110 kg. The mean backfat depth was increased while leaf lard weights were decreased by probiotic supplementation. Ingestion of probiotics decreased the serum triglyceride and glucose concentrations, but did not change the levels of total cholesterol and free fatty acids in the serum. The mRNA expressions of fatty acid synthase (FAS) and acetyl-CoA carboxylase α (ACCα) in the liver were down-regulated by the dietary probiotic supplement. Conversely, the gene expressions of FAS and ACCα in the adipose tissue increased. The probiotic diet decreased the copy numbers and percentage of Bacteroidetes, while it increased the percentage of Firmicutes in the cecal contents. We conclude that the addition of B. subtilis improves growth performance and up-regulates lipid metabolism in subcutaneous fat of finishing pigs. We conclude that B. subtilis affects lipid metabolism through regulation of the proportion of Bacteroidetes and Firmicutes in the gut.

Transcriptional repression by Drosophila methyl-CpG-binding proteins

C methylation at genomic CpG dinucleotides has been implicated in the regulation of a number of genetic activities during vertebrate cell differentiation and embryo development. The methylated CpG could induce chromatin condensation through the recruitment of histone deacetylase (HDAC)-containing complexes by methyl-CpG-binding proteins. These proteins consist of the methylated-DNA binding domain (MBD). Unexpectedly, however, several studies have identified MBD-containing proteins encoded by genes of Drosophila melanogaster, an invertebrate species supposed to be void of detectable m(5)CpG. We now report the genomic structure of a Drosophila gene, dMBD2/3, that codes for two MBD-containing, alternatively spliced, and developmentally regulated isoforms of proteins, dMBD2/3 and dMBD2/3Delta. Interestingly, in vitro binding experiments showed that as was the case for vertebrate MBD proteins, dMBD2/3Delta could preferentially recognize m(5)CpG-containing DNA through its MBD. Furthermore, dMBD2/3Delta as well as one of its orthologs in mouse, MBD2b, could function in human cells as a transcriptional corepressor or repressor. The activities of HDACs appeared to be dispensable for transcriptional repression by dMBD2/3Delta. Finally, dMBD2/3Delta also could repress transcription effectively in transfected Drosophila cells. The surprisingly similar structures and characteristics of the MBD proteins as well as DNA cytosine (C-5) methyltransferase-related proteins in Drosophila and vertebrates suggest interesting scenarios for their roles in eukaryotic cellular functions.

Drosophila proteins related to vertebrate DNA (5-cytosine) methyltransferases

DNA methylation at CpG residues is closely associated with a number of biological processes during vertebrate development. Unlike the vertebrates, however, several invertebrate species, including the Drosophila, do not have apparent DNA methylation in their genomes. Nor have there been reports on a DNA (5-cytosine) methyltransferase (CpG MTase) found in these invertebrates. We now present evidence for two CpG MTase-like proteins expressed in Drosophila cells. One of these, DmMTR1, is a protein containing peptide epitopes immunologically related to the conserved motifs I and IV in the catalytic domain of the mammalian dnmt1. DmMTR1 has an apparent molecular mass of 220 kDa and, similar to mammalian dnmt1, it also interacts in vivo with the proliferating cell nuclear antigen. During interphase of the syncytial Drosophila embryos, the DmMTR1 molecules are located outside the nuclei, as is dnmt1 in the mouse blastocyst. However, DmMTR1 appears to be rapidly transported into, and then out of the nuclei again, as the embryos undergo mitotic waves. Immunofluorescent data indicate that DmMTR1 molecules "paint" the whole set of condensed Drosophila chromosomes throughout the mitotic phase, suggesting they may play an essential function in the cell-cycle regulated condensation of the Drosophila chromosomes. Through search in the genomic database, we also have identified a Drosophila polypeptide, DmMT2, that exhibits high sequence homology to the mammalian dnmt2 and the yeast CpG MTase homolog pmt1. The expression of DmMT2 appears to be developmentally regulated. We discuss the evolutionary and functional implications of the discovery of these two Drosophila proteins related to mammalian CpG MTases.

Interaction of WW domains with hematopoietic transcription factor p45/NF-E2 and RNA polymerase II

NF-E2 is an erythroid-specific transcription factor required for expression of several erythroid-specific genes. By Far-Western blotting and yeast two-hybrid assay, we demonstrate that p45, the large subunit of NF-E2, is capable of binding to a specific set of WW domain-containing proteins, including the ubiquitin ligase hRPF1. This binding is mediated through the interaction between the WW domains and a PY motif located within the amino-terminal region of p45. Interestingly, the carboxyl-terminal domain of mammalian RNA polymerase II binds a similar set of WW domains to which p45 interacts with. We discuss the data in terms of possible new pathways through which the processes of transcriptional regulation by NF-E2 could be regulated in erythroid and megakaryote cells.

Cleavage patterns of Drosophila melanogaster satellite DNA by restriction enzymes

The five satellite DNAs of Drosophila melanogaster have been isolated by the combined use of different equilibrium density gradients and hydrolyzed by seven different restriction enzymes; Hae III, Hind II + Hind III, Hinf, Hpa II, EcoR I and EcoR II. The 1.705 satellite is not hydrolyzed by any of the enzymes tested. Hae III is the only restriction enzyme that cuts the 1.672 and 1.686 satellites. The cleavage products from either of these reactions has a heterogeneous size distribution. Part of the 1.688 satellite is cut by Hae III and by Hinf into three discrete fragments with M.W. that are multiples of 2.3 X 10(5) daltons (approximately 350 base pairs). In addition, two minor bands are detected in the 1.688-Hinf products. The mole ratios of the trimer, dimer and monomer are: 1:6.30 : 63.6 for 1.688-Hae III and 1 : 22.0 : 403 for 1.688-Hinf. Circular mitochondrial DNA (rho = 1.680) is cut into discrete fragments by all of the enzymes tested and molecular weights of these fragments have been determined.