Emodin Decreases Hepatic Hypoxia-Inducible Factor-1[Formula: see text] by Inhibiting its Biosynthesis

HEPATOCELLULAR TOXICITY OF THE METABOLITE EMODIN PRODUCED BY THE COMMON BUCKTHORN (RHAMNUS CATHARTICA) IN GREEN FROG (LITHOBATES CLAMITANS) TADPOLES

The secondary metabolite emodin, produced by the widely distributed invasive shrub known as the common buckthorn (Rhamnus cathartica), has been shown to produce deformities and mortality in invertebrates, fish, and amphibian larvae. Here, we describe the effects on the liver of green frog (Lithobates clamitans) tadpoles after 21 d of exposure to high concentrations of emodin in a controlled environment. Histopathologic analysis showed fibrosis, bile duct proliferation, hepatocellular swelling, and accumulations of flocculent material consistent with emodin within the gall bladder and bile ducts of exposed individuals. The extensive fibrosis produced probably impeded the blood flow within the portal triads, limiting the detoxification function of the liver and resulting in hepatocellular necrosis and premature death for the individuals exposed. Exposure to emodin in the environment could represent a significant threat to developing amphibian larvae and contribute to local declines of populations.

Advances in the study of emodin: an update on pharmacological properties and mechanistic basis

Rhei Radix et Rhizoma, also known as rhubarb or Da Huang, has been widely used as a spice and as traditional herbal medicine for centuries, and is currently marketed in China as the principal herbs in various prescriptions, such as Da-Huang-Zhe-Chong pills and Da-Huang-Qing-Wei pills. Emodin, a major bioactive anthraquinone derivative extracted from rhubarb, represents multiple health benefits in the treatment of a host of diseases, such as immune-inflammatory abnormality, tumor progression, bacterial or viral infections, and metabolic syndrome. Emerging evidence has made great strides in clarifying the multi-targeting therapeutic mechanisms underlying the efficacious therapeutic potential of emodin, including anti-inflammatory, immunomodulatory, anti-fibrosis, anti-tumor, anti-viral, anti-bacterial, and anti-diabetic properties. This comprehensive review aims to provide an updated summary of recent developments on these pharmacological efficacies and molecular mechanisms of emodin, with a focus on the underlying molecular targets and signaling networks. We also reviewed recent attempts to improve the pharmacokinetic properties and biological activities of emodin by structural modification and novel material-based targeted delivery. In conclusion, emodin still has great potential to become promising therapeutic options to immune and inflammation abnormality, organ fibrosis, common malignancy, pathogenic bacteria or virus infections, and endocrine disease or disorder. Scientifically addressing concerns regarding the poor bioavailability and vague molecular targets would significantly contribute to the widespread acceptance of rhubarb not only as a dietary supplement in food flavorings and colorings but also as a health-promoting TCM in the coming years.

Cancer cachexia has many symptoms but only one cause: anoxia

During nearly 100 years of research on cancer cachexia (CC), science has been reciting the same mantra: it is a multifactorial syndrome. The aim of this paper is to show that the symptoms are many, but they have a single cause: anoxia. CC is a complex and devastating condition that affects a high proportion of advanced cancer patients. Unfortunately, it cannot be reversed by traditional nutritional support and it generally reduces survival time. It is characterized by significant weight loss, mainly from fat deposits and skeletal muscles. The occurrence of cachexia in cancer patients is usually a late phenomenon. The conundrum is why do similar patients with similar tumors, develop cachexia and others do not? Even if cachexia is mainly a metabolic dysfunction, there are other issues involved such as the activation of inflammatory responses and crosstalk between different cell types.  The exact mechanism leading to a wasting syndrome is not known, however there are some factors that are surely involved, such as anorexia with lower calorie intake, increased glycolytic flux, gluconeogenesis, increased lipolysis and severe tumor hypoxia. Based on this incomplete knowledge we put together a scheme explaining the molecular mechanisms behind cancer cachexia, and surprisingly, there is one cause that explains all of its characteristics: anoxia.  With this different view of CC we propose a treatment based on the physiopathology that leads from anoxia to the symptoms of CC.  The fundamentals of this hypothesis are based on the idea that CC is the result of anoxia causing intracellular lactic acidosis. This is a dangerous situation for cell survival which can be solved by activating energy consuming gluconeogenesis. The process is conducted by the hypoxia inducible factor-1α. This hypothesis was built by putting together pieces of evidence produced by authors working on related topics.

Modified Da-chai-hu Decoction regulates the expression of occludin and NF-κB to alleviate organ injury in severe acute pancreatitis rats

Modified Da-chai-hu Decoction (MDD), a traditional Chinese medicinal formulation, which was empirically generated from Da-chai-hu decoction, has been utilized to treat severe acute pancreatitis (SAP) for decades. The aim of the present study was to explore its potential organprotective mechanism in SAP. In the present study, rat SAP model was induced by retrograde injection of 3.5% sodium taurocholate into the biliopancreatic duct, MDD (23.35 g/kg body weight, twelve times the clinical dose) were orally given at 2 h before and 10 h after injection. At 12 h after model induction, blood was taken from vena cava for analysis of amylase, diamine oxidase (DAO), pulmonary surfactant protein-A (SP-A), and C-reactive protein (CRP). Histopathological change of pancreas, ileum and lung was assayed by H&E staining, myeloperoxidase (MPO) activity were determinated using colorimetric assay, and the expressions of occludin and nuclear factor-κB (NF-κB) were detected by real-time RT-PCR and western blot, respectively. In addition, the tissue concentrations of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and monocyte chemoattractant protein-1 (MCP-1) were measured by enzyme-linked immunosorbent assay (ELISA). The results showed that in SAP rats, MDD significantly alleviated histopathological damage, depressed the MPO activity and the concentrations of TNF-α, IL-1β, and MCP-1 of pancreas, ileum and lung, and reduced the serum levels of amylase [(3283.4 ± 585.5) U·L^-1vs (5626.4 ± 795.1)U·L^-1], DAO [(1100.1 ± 334.3) U·L^-1vs (1666.4 ± 525.3) U·L^-1] and CRP [(7.6 ± 1.2) μg·mL^-1vs (17.8 ± 3.8) μg·mL^-1]. However, the serum SP-A concentration [(106.1 ± 16.6) pg·mL^-1vs (90.1 ± 14.9) pg·mL^-1] was elevated when treated SAP rats with MDD. Furthermore, MDD increased the occludin expression and reduced the NF-κB expression in pancreas, ileum and lung of SAP rats. Our findings suggested that MDD administration was an effective therapeutic approach for SAP treatment. It could up-regulate occludin expression to protect intercellular tight junction and down-regulate NF-κB expression to inhibit inflammatory reaction of pancreas, ileum and lung.

Rhein enhances the cytotoxicity of effector lymphocytes in colon cancer under hypoxic conditions

The immunosuppressive tumor microenvironment limits the application of adoptive immunotherapy for solid tumors. Hypoxia is closely associated with the formation of the immunosuppressive tumor microenvironment. Hypoxia-inducible factor-1 (HIF-1) is an oxygen-sensitive transcriptional activator that drives the transcription of several immunosuppressive molecules. In addition, previous studies confirmed that rhein downregulated the expression of HIF-1α, a subunit of HIF-1, in pancreatic cancer cells. The present study established correlations between mRNA expression levels of HIF-1α and six immunosuppressive molecules in colorectal cancer (CRC) tissue samples. This study examined the effect of rhein on the expression levels of HIF-1α and six immunosuppressive molecules in CRC cell lines under hypoxic conditions by western blot analysis and reverse transcription-quantitative polymerase chain reaction. This study demonstrated that rhein downregulated the expression of HIF-1α and immunosuppressive molecules in CRC cells under hypoxic conditions. In addition, the present study analyzed the cytotoxicity of peripheral blood lymphocytes in vitro using a non-toxic cytotoxicity assay. This study demonstrated that in vitro, rhein enhanced the cytotoxicity of effector lymphocytes toward tumor cells under hypoxic conditions, and therefore rhein may be used in combination with effector lymphocytes for the treatment of CRC.

Emodin and rhein decrease levels of hypoxia-inducible factor-1α in human pancreatic cancer cells and attenuate cancer cachexia in athymic mice carrying these cells

The transcription factor hypoxia-inducible factor-1 (HIF-1) consists of oxygen-sensitive HIF-1α and constitutive HIF-1β. HIF-1α is undetectable in normal cells, but cancer cells frequently express HIF-1α to support their growth, angiogenesis, and high glycolysis (also known as the Warburg effect). The Warburg effect in cancer cells increases energy expenditure and thus participates in cancer-induced metabolic disorder, cancer cachexia. In the present study, we investigated whether two components of Rheum palmatum, emodin and rhein, inhibited HIF-1α expression in human pancreatic cancer cells and whether the inhibiting effect, if any, attenuated cancer cachexia. Using Western blotting, we demonstrated that emodin and rhein decreased HIF-1α expression in MiaPaCa2 and four other human pancreatic cancer cell lines. We also examined HIF-1α expression when MiaPaCa2 cells were exposed to PX-478, noscapine, and phenethyl isothiocyanate, as these compounds were known to inhibit HIF-1α expression in different cancer cells. PX-478 and noscapine inhibited HIF-1α expression to a less extent than emodin and rhein, and phenethyl isothiocyanate did not inhibit HIF-1α expression in tested concentrations. We obtained evidence that emodin and rhein decreased HIF-1α by decreasing its biosynthesis but not gene transcription or protein stability. When MiaPaCa2 cells were implanted in athymic mice, emodin and rhein inhibited cancer-cell growth and HIF-1α expression. In these athymic mice, emodin and rhein also attenuated two pathological constituents of cancer cachexia, namely high hepatic gluconeogenesis and skeletal-muscle proteolysis. In conclusion, emodin and rhein decrease pancreatic cancer cell's growth and HIF-1α expression and attenuate cancer cachexia in the athymic mice carrying the cancer cells.