Characterization of liver injury, oval cell proliferation and cholangiocarcinogenesis in glutathione S-transferase A3 knockout mice

Antioxidant, anti-inflammatory, and anti-apoptotic effects of genkwanin against aflatoxin B1-induced testicular toxicity

Aflatoxin B1 (AFB1) is the most hazardous aflatoxin that causes significant damage to the male reproductive system. Genkwanin (GNK) is a bioactive flavonoid that shows antioxidant and anti-inflammatory potential. Therefore, the current study was planned to evaluate the effects of GNK against AFB1-induced testicular toxicity. Forty-eight male rats were distributed into four groups (n = 12 rats). AFB1 (50 μg/kg) and GNK (20 mg/kg) were administered to the rats for eight weeks. Results of the current study revealed that AFB1 exposure induced adverse effects on the Nrf2/Keap1 pathway and reduced the expressions and activities of antioxidant enzymes. Additionally, it increased the levels of oxidative stress markers. Furthermore, expressions of steroidogenic enzymes were down-regulated by AFB1 intoxication. Besides, AFB1 exposure reduced the levels of gonadotropins and plasma testosterone, which subsequently reduced the epididymal sperm count, motility, and hypo-osmotic swelled (HOS) sperms, while increasing the number of dead sperms and causing morphological anomalies of the head, midpiece, and tail of the sperms. In addition, AFB1 decreased the activities of testicular function marker enzymes and the levels of inflammatory markers. Moreover, it severely affected the apoptotic profile by up-regulating the expressions of Bax and Casp3, while down-regulating the Bcl2 expression. Besides, AFB1 significantly damaged the histoarchitecture of testicular tissues. However, GNK treatment reversed all the AFB1-induced damages in the rats. Taken together, the current study reports the potential use of GNK as a therapeutic agent to prevent AFB1-induced testicular toxicity due to its antioxidant, anti-inflammatory, and anti-apoptotic properties.

Molecular Signatures Integral to Natural Reprogramming in the Pigment Epithelium Cells after Retinal Detachment in Pleurodeles waltl

The reprogramming of retinal pigment epithelium (RPE) cells into retinal cells (transdifferentiation) lies in the bases of retinal regeneration in several Urodela. The identification of the key genes involved in this process helps with looking for approaches to the prevention and treatment of RPE-related degenerative diseases of the human retina. The purpose of our study was to examine the transcriptome changes at initial stages of RPE cell reprogramming in adult newt Pleurodeles waltl. RPE was isolated from the eye samples of day 0, 4, and 7 after experimental surgical detachment of the neural retina and was used for a de novo transcriptome assembly through the RNA-Seq method. A total of 1019 transcripts corresponding to the differently expressed genes have been revealed in silico: the 83 increased the expression at an early stage, and 168 increased the expression at a late stage of RPE reprogramming. We have identified up-regulation of classical early response genes, chaperones and co-chaperones, genes involved in the regulation of protein biosynthesis, suppressors of oncogenes, and EMT-related genes. We revealed the growth in the proportion of down-regulated ribosomal and translation-associated genes. Our findings contribute to revealing the molecular mechanism of RPE reprogramming in Urodela.

Gender Differences in Oxidative Stress in Relation to Cancer Susceptibility and Survival

Genetic, developmental, biochemical, and environmental variables interact intricately to produce sex differences. The significance of sex differences in cancer susceptibility is being clarified by numerous studies. Epidemiological research and cancer registries have revealed over the past few years that there are definite sex variations in cancer incidence, progression, and survival. However, oxidative stress and mitochondrial dysfunction also have a significant impact on the response to treatment of neoplastic diseases. Young women may be more protected from cancer than men because most of the proteins implicated in the regulation of redox state and mitochondrial function are under the control of sexual hormones. In this review, we describe how sexual hormones control the activity of antioxidant enzymes and mitochondria, as well as how they affect several neoplastic diseases. The molecular pathways that underlie the gender-related discrepancies in cancer that have been identified may be better understood, which may lead to more effective precision medicine and vital information on treatment options for both males and females with neoplastic illnesses.

Criteria for preclinical models of cholangiocarcinoma: scientific and medical relevance

Cholangiocarcinoma (CCA) is a rare malignancy that develops at any point along the biliary tree. CCA has a poor prognosis, its clinical management remains challenging, and effective treatments are lacking. Therefore, preclinical research is of pivotal importance and necessary to acquire a deeper understanding of CCA and improve therapeutic outcomes. Preclinical research involves developing and managing complementary experimental models, from in vitro assays using primary cells or cell lines cultured in 2D or 3D to in vivo models with engrafted material, chemically induced CCA or genetically engineered models. All are valuable tools with well-defined advantages and limitations. The choice of a preclinical model is guided by the question(s) to be addressed; ideally, results should be recapitulated in independent approaches. In this Consensus Statement, a task force of 45 experts in CCA molecular and cellular biology and clinicians, including pathologists, from ten countries provides recommendations on the minimal criteria for preclinical models to provide a uniform approach. These recommendations are based on two rounds of questionnaires completed by 35 (first round) and 45 (second round) experts to reach a consensus with 13 statements. An agreement was defined when at least 90% of the participants voting anonymously agreed with a statement. The ultimate goal was to transfer basic laboratory research to the clinics through increased disease understanding and to develop clinical biomarkers and innovative therapies for patients with CCA.

Dissecting novel mechanisms of hepatitis B virus related hepatocellular carcinoma using meta-analysis of public data

BACKGROUND

Hepatitis B virus (HBV) is a cause of hepatocellular carcinoma (HCC). Interestingly, this process is not necessarily mediated through cirrhosis and may in fact involve oncogenic processes. Prior studies have suggested specific oncogenic gene expression pathways were affected by viral regulatory proteins. Thus, identifying these genes and associated pathways could highlight predictive factors for HCC transformation and has implications in early diagnosis and treatment.

AIM

To elucidate HBV oncogenesis in HCC and identify potential therapeutic targets.

METHODS

We employed our Search, Tag, Analyze, Resource platform to conduct a meta-analysis of public data from National Center for Biotechnology Information’s Gene Expression Omnibus. We performed meta-analysis consisting of 155 tumor samples compared against 185 adjacent non-tumor samples and analyzed results with ingenuity pathway analysis.

RESULTS

Our analysis revealed liver X receptors/retinoid X receptor (RXR) activation and farnesoid X receptor/RXR activation as top canonical pathways amongst others. Top upstream regulators identified included the Ras family gene rab-like protein 6 (RABL6). The role of RABL6 in oncogenesis is beginning to unfold but its specific role in HBV-related HCC remains undefined. Our causal analysis suggests RABL6 mediates pathogenesis of HBV-related HCC through promotion of genes related to cell division, epigenetic regulation, and Akt signaling. We conducted survival analysis that demonstrated increased mortality with higher RABL6 expression. Additionally, homeobox A10 (HOXA10) was a top upstream regulator and was strongly upregulated in our analysis. HOXA10 has recently been demonstrated to contribute to HCC pathogenesis in vitro. Our causal analysis suggests an in vivo role through downregulation of tumor suppressors and other mechanisms.

CONCLUSION

This meta-analysis describes possible roles of RABL6 and HOXA10 in the pathogenesis of HBV-related HCC. RABL6 and HOXA10 represent potential therapeutic targets and warrant further investigation.

Early Deregulation of Cholangiocyte NR0B2 During Primary Sclerosing Cholangitis

Background and Aims

Primary sclerosing cholangitis (PSC) is a probable autoimmune liver disease characterized by persistent and progressive biliary inflammation that leads to biliary infection, cirrhosis, or cholangiocarcinoma. Genome-wide omics data are scarce regarding this severe disease.

Methods

MEDLINE database gene prioritization by text mining (biliary inflammation, biliary fibrosis, biliary stasis) was integrated in distinct omics data: (1) PSC liver transcriptome training and validation cohorts, (2) farnesoid X receptor (FXR) mice liver transcriptome subjected to an FXR agonist or FXR knockout mice; (3) liver single-cell transcriptome of the Abcb4-/- mice model of PSC.

Results

A liver molecular network highlighted the involvement of nuclear receptor subfamily 0 group B member 2 (NR0B2) and its associated nuclear receptor FXR in a metabolic cascade that may influence the immune response. NR0B2 upregulation in PSC liver was independent of gender, age, body mass index, liver fibrosis, and PSC complications. Heterogeneity of NR0B2 upregulation was found in cholangiocyte cell types in which the NR0B2-based cell fate decision revealed the involvement of several metabolic pathways for detoxification (sulfur, glutathione derivative, and monocarboxylic acid metabolisms). Genes potentially implicated in carcinogenesis were also discovered on this cholangiocyte trajectory: GSTA3, inhibitor of DNA binding 2, and above all, TMEM45A, a transmembrane molecule from the Golgi apparatus considered as oncogenic in several cancers.

Conclusion

By revisiting PSC through PubMed data mining, we evidenced the early cholangiocyte deregulation of NR0B2, highlighting a metabolic and premalignant reprogramming of the cholangiocyte cell type. The therapeutic targeting of NR0B2 could potentiate that of FXR and enable action on early events of the disease and prevent its progression.

Regulatory network identified by pulmonary transcriptome and proteome profiling reveals extensive change of tumor-related genes in microRNA-21 knockout mice

PURPOSE

MicroRNA-21 (miR-21) is a well-known oncomiR and plays key roles in regulating various biological processes related to pulmonary diseases, especially lung carcinoma. The regulatory roles and downstream targets of miR-21 remain far from well understood. We aimed to identify miR-21-gene regulatory network in lung tissue.

METHODS

Transcriptome and proteome analyses were performed on lung tissues from miR-21 knockout (KO) mice and their wildtype (WT) littermates. Differentially expressed genes (DEGs) and proteins (DEPs) between miR-21KO and WT were analyzed, and correlation analysis was performed between transcriptional and translational level. DEPs were used for prediction of miR-21 target genes and construction of co-expression network.

RESULTS

Comparing with WT mice, 820 DEGs and 623 DEPs were identified in lung tissues of miR-21KO mice. Upregulated DEGs and DEPs were both significantly enriched in pathways of metabolism of xenobiotics by cytochrome P450, drug metabolism, and chemical carcinogenesis. Of the 31 molecules commonly identified in DEGs and DEPs, 9 upregulated genes were tumor suppressor genes while 8 downregulated genes were oncogenes, and 12 genes showed closely positive correlation between mRNA and protein expression. Real-time PCR validation results were consistent with the omics data. Among the upregulated DEPs in miR-21KO mice, 21 genes were predicted as miR-21 targets. The miR-21 regulatory network was constructed by target genes and their highly co-expressed proteins, which identified the miR-21 target Itih4 as a hub gene.

CONCLUSION

MiR-21-gene regulatory network was constructed in mouse lung tissue. MiR-21KO resulted in extensive upregulation of tumor suppressor genes and downregulation of oncogenes.

HIF-2α-targeted interventional chemoembolization multifunctional microspheres for effective elimination of hepatocellular carcinoma

Transcatheter arterial chemoembolization (TACE) is widely used for the treatment of advanced hepatocellular carcinoma (HCC). However, the long-term hypoxic microenvironment caused by TACE seriously affects the therapeutic effect of TACE. HIF-2α plays a crucial role on the chronic hypoxia process, which might be an ideal target for TACE therapy. Herein, a multifunctional polyvinyl alcohol (PVA)/hyaluronic acid (HA)-based microsphere (PT/DOX-MS) co-loaded with doxorubicin (DOX) and PT-2385, an effective HIF-2α inhibitor, was developed for enhanced TACE treatment efficacy. In vitro and in vivo studies revealed that PT/DOX-MS had a superior ability to treat HCC by blocking the tumor cells in G2/M phase, prompting cell apoptosis, and inhibiting tumor angiogenesis. The antitumor mechanisms of PT/DOX-MS were possibly due to that the introduction of PT-2385 could effectively inhibit the expression level of HIF-2α in hypoxic HCC cells, thereby down-regulating the expression levels of Cyclin D1, VEGF and TGF-α. In addition, the combination of DOX and PT-2385 could jointly inhibit VEGF expression, which was another reason accounting for the combined anti-cancer effect of PT/DOX-MS. Overall, our study demonstrated that PT/DOX-MS is a promising embolic agent for enhanced HCC treatment via the combined effect of hypoxia microenvironment improvement, chemotherapy, and embolization.

The Intervention and Mechanism of Action for Aloin against Subchronic Aflatoxin B1 Induced Hepatic Injury in Rats

As a class of difurancoumarin compounds with similar structures, aflatoxins (AF) are commonly found in the environment, soil, and food crops. AF pose a serious threat to the health of humans, poultry, and livestock. This study aimed to investigate the neuroprotective effect and detailed mechanism of aloin on hepatic injury induced by subchronic AFB1 in rats. The result showed that aloin could significantly inhibit the decrease in food intake, body weight growth, immune organ index, and serum albumin content caused by long-term AFB1 exposure. Meanwhile, aloin reduced the level of serum liver function and improved renal swelling and pathological changes of liver tissue. Aloin could also inhibit liver lipid peroxidation and improve liver antioxidant capacity. Further investigation revealed that aloin inhibited the activity and expression of hepatic CYP1A2 and CYP3A4 and down-regulated IL-1β expression in subchronic AFB1-induced liver injury rats. The above study demonstrated that aloin played an important role in blocking or delaying the development process of subchronic AFB1-induced hepatotoxicity. Therefore, aloin is considered to have a potential role as a protective agent against AFB1.

Subcellular spatio-temporal intravital kinetics of aflatoxin B1 and ochratoxin A in liver and kidney

Local accumulation of xenobiotics in human and animal tissues may cause adverse effects. Large differences in their concentrations may exist between individual cell types, often due to the expression of specific uptake and export carriers. Here we established a two-photon microscopy-based technique for spatio-temporal detection of the distribution of mycotoxins in intact kidneys and livers of anesthetized mice with subcellular resolution. The mycotoxins ochratoxin A (OTA, 10 mg/kg b.w.) and aflatoxin B1 (AFB1, 1.5 mg/kg b.w.), which both show blue auto-fluorescence, were analyzed after intravenous bolus injections. Within seconds after administration, OTA was filtered by glomeruli, and enriched in distal tubular epithelial cells (dTEC). A striking feature of AFB1 toxicokinetics was its very rapid uptake from sinusoidal blood into hepatocytes (t1/2 ~ 4 min) and excretion into bile canaliculi. Interestingly, AFB1 was enriched in the nuclei of hepatocytes with zonal differences in clearance. In the cytoplasm of pericentral hepatocytes, the half-life (t1/2~ 63 min) was much longer compared to periportal hepatocytes of the same lobules (t1/2 ~ 9 min). In addition, nuclear AFB1 from periportal hepatocytes cleared faster compared to the pericentral region. These local differences in AFB1 clearance may be due to the pericentral expression of cytochrome P450 enzymes that activate AFB1 to protein- and DNA-binding metabolites. In conclusion, the present study shows that large spatio-temporal concentration differences exist within the same tissues and its analysis may provide valuable additional information to conventional toxicokinetic studies.

Research progress on the protection and detoxification of phytochemicals against aflatoxin B1-Induced liver toxicity

Aflatoxin B₁ (AFB₁) is a potent hepatotoxic toxin, which can cause hepatitis, cirrhosis, and liver immunological damage. It has been involved in the etiology of human hepatocellular carcinoma. AFB₁ can cause oxidative stress in the body's metabolism process, and then cause cytotoxicity, such as apoptosis and DNA damage. Scientific research has discovered that phytochemicals can induce the detoxification pathway of AFB₁ through its biotransformation, thereby reducing the damage of AFB₁ to the human body. In clinical treatment, certain phytochemicals have been effectively used in the treatment of liver injury due to the advantages of multiple targets, multiple pathways, low toxicity and side effects. Therefore, the article summarizes the toxic mechanism of AFB₁-induced hepatoxicity, and the related research progress of phytochemicals for preventing and treating its cytotoxicity and genotoxicity. We also look forward to the existing problems and application prospects of phytochemicals in the pharmaceutical industry, in order to provide theoretical reference for the prevention and treatment of AFB₁ poisoning in future research work.

NRF2 and the Ambiguous Consequences of Its Activation during Initiation and the Subsequent Stages of Tumourigenesis

NF-E2 p45-related factor 2 (NRF2, encoded in the human by NFE2L2) mediates short-term adaptation to thiol-reactive stressors. In normal cells, activation of NRF2 by a thiol-reactive stressor helps prevent, for a limited period of time, the initiation of cancer by chemical carcinogens through induction of genes encoding drug-metabolising enzymes. However, in many tumour types, NRF2 is permanently upregulated. In such cases, its overexpressed target genes support the promotion and progression of cancer by suppressing oxidative stress, because they constitutively increase the capacity to scavenge reactive oxygen species (ROS), and they support cell proliferation by increasing ribonucleotide synthesis, serine biosynthesis and autophagy. Herein, we describe cancer chemoprevention and the discovery of the essential role played by NRF2 in orchestrating protection against chemical carcinogenesis. We similarly describe the discoveries of somatic mutations in NFE2L2 and the gene encoding the principal NRF2 repressor, Kelch-like ECH-associated protein 1 (KEAP1) along with that encoding a component of the E3 ubiquitin-ligase complex Cullin 3 (CUL3), which result in permanent activation of NRF2, and the recognition that such mutations occur frequently in many types of cancer. Notably, mutations in NFE2L2, KEAP1 and CUL3 that cause persistent upregulation of NRF2 often co-exist with mutations that activate KRAS and the PI3K-PKB/Akt pathway, suggesting NRF2 supports growth of tumours in which KRAS or PKB/Akt are hyperactive. Besides somatic mutations, NRF2 activation in human tumours can occur by other means, such as alternative splicing that results in a NRF2 protein which lacks the KEAP1-binding domain or overexpression of other KEAP1-binding partners that compete with NRF2. Lastly, as NRF2 upregulation is associated with resistance to cancer chemotherapy and radiotherapy, we describe strategies that might be employed to suppress growth and overcome drug resistance in tumours with overactive NRF2.

Lower concentrations of curcumin inhibit Her2-Akt pathway components in human breast cancer cells, and other dietary botanicals potentiate this and lapatinib inhibition

Her2-dependent breast cancer is treated with pharmacological drugs (eg, Herceptin, lapatinib) that target Her2 signaling. Curcumin has emerged as a potential co-treatment for this and other cancers, but prior studies have focused on non-attainable concentrations. Here we test the hypothesis that attainable in vivo levels of dietary curcumin can reduce Her2 signaling. Consistent with previous studies, higher dose curcumin (18 μmol/L) inhibits Her2-Akt pathway signaling (pHer2, total Her2 and pAkt levels) and cell growth using AU565 human breast cancer cells. We then examined lower, more physiologically relevant concentrations of curcumin, alone and in combination with other dietary botanicals (quercetin and OptiBerry fruit extract). At 4 μmol/L, curcumin reduced Her2 signaling, and even more when combined with quercetin or OptiBerry. At 1.5 μmol/L curcumin, pHer2 and Her2 (but not pAkt) were reduced, with all three pathway markers reduced more in the presence of quercetin. We also found that 1.5 μmol/L curcumin strongly potentiated lapatinib inhibition of Her2-Akt pathway signaling, and more so for pAkt, when combined with quercetin plus OptiBerry (CQO). Parallel analyses revealed cell growth inhibition at 18 and 4 μmol/L but not 1.5 μmol/L curcumin, and potentiation of 1.5 μmol/L curcumin growth arrest with other botanicals +/- lapatinib. These studies demonstrate that a physiological attainable level of curcumin (1.5 μmol/L) can reduce some components of the critical Her2-Akt pathway; that even more complete inhibition can be achieved by combination with other dietary botanicals; and that curcumin and other botanicals can potentiate the action of the Her2-cancer metastatic drug lapatinib, in turn suggesting the potential anti-cancer clinical use of these botanicals.

Nrf2 in liver toxicology

Liver plays essential roles in the metabolism of many endogenous chemicals and exogenous toxicants. Mechanistic studies in liver have been at the forefront of efforts to probe the roles of bioactivation and detoxication of environmental toxins and toxicants in hepatotoxicity. Moreover, idiosyncratic hepatoxicity remains a key barrier in the clinical development of drugs. The now vast Nrf2 field emerged in part from biochemical and molecular studies on chemical inducers of hepatic detoxication enzymes and subsequent characterization of the modulation of drug/toxicant induced hepatotoxicities in mice through disruption of either Nrf2 or Keap1 genes. In general, loss of Nrf2 increases the sensitivity to such toxic chemicals, highlighting a central role of this transcription factor and its downstream target genes as a modifier to chemical stress. In this review, we summarize the impact of Nrf2 on the toxicology of multiple hepatotoxicants, and discuss efforts to utilize the Nrf2 response in predictive toxicology.

GSTA3 regulates TGF-1-induced renal interstitial fibrosis in NRK-52E cells as a component of the PI3K-Keap1/Nrf2 pathway

Objective

To evaluate the effect of GSTA3 within the PI3K–Keap1/Nrf2 pathway in renal interstitial fibrosis (RIF).

Methods

An in vitro RIF model with TGF-β1 stimulation in NRK-52E cells was established to identify potential signaling pathways that modulate GSTA3. Changes in GSTA3 expression were observed in the RIF model after silencing or enhancing Nrf2 expression. Changes in GSTA3, Keap1, and Nrf2 expression were detected after blocking the upstream of the Keap1/Nrf2 signaling pathway (including MAPK and PI3K/Akt). The effect of Nrf2 on GSTA3 expression was evaluated by overexpressing Nrf2.

Results

Protein and mRNA levels of GSTA3, FN, Nrf2, and Keap1 were significantly increased after TGF-β1 stimulation. GSTA3 was also upregulated following overexpression of Nrf2. TGF-β1 activated the PI3K/Akt signaling pathway, leading to RIF. After blocking this pathway, the production of superoxide dismutase, reactive oxygen species, and fibronectin were reduced. The MAPK pathway was not involved in the development of RIF via regulating GSTA3 expression.

Conclusions

The PI3K–KEAP1/Nrf2–GSTA3 signaling pathway is a possible mechanism of resisting external stimulation of renal fibrosis factors, regulating oxidative stress, and preventing RIF.

A novel role of glutathione S-transferase A3 in inhibiting hepatic stellate cell activation and rat hepatic fibrosis

Background and aims

Glutathione S-transferase A3 (GSTA3) is known as an antioxidative protease, however, the crucial role of GSTA3 in liver fibrosis remains unclear. As a recently we developed water-soluble pyridone agent with antifibrotic features, fluorofenidone (AKF-PD) can attenuate liver fibrosis, present studies were designed to explore the role of GSTA3 in liver fibrosis and its modulation by AKF-PD in vivo and in vitro.

Methods

Rats liver fibrosis models were induced by dimethylnitrosamine (DMN) or carbon tetrachloride (CCl4). The two activated hepatic stellate cells (HSCs) lines, rat CFSC-2G and human LX2 were treated with AKF-PD respectively. The lipid peroxidation byproduct malondialdehyde (MDA) in rat serum was determined by ELISA. The accumulation of reactive oxygen species (ROS) was measured by dichlorodihydrofluorescein fluorescence analysis. The expression of α-smooth muscle actin (α-SMA), fibronectin (FN), and phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2), p38 mitogen-activated protein kinase (p38 MAPK), c-Jun N-terminal kinase (JNK) and glycogen synthase kinase 3 beta (GSK-3β) were detected by western blotting (WB).

Results

GSTA3 was substantially reduced in the experimental fibrotic livers and transdifferentiated HSCs. AKF-PD alleviated rat hepatic fibrosis and potently inhibited HSCs activation correlated with restoring GSTA3. Moreover, GSTA3 overexpression prevented HSCs activation and fibrogenesis, while GSTA3 knockdown enhanced HSCs activation and fibrogenesis resulted from increasing accumulation of ROS and subsequent amplified MAPK signaling and GSK-3β phosphorylation.

Conclusions

We demonstrated firstly that GSTA3 inhibited HSCs activation and liver fibrosis through suppression of the MAPK and GSK-3β signaling pathways. GSTA3 may represent a promising target for potential therapeutic intervention in liver fibrotic diseases.

Identification and expression profile of Delta-GST in black tiger shrimp (Penaeus monodon) exposed to aflatoxin B1 (AFB1)

Delta GST is an insect-specific class and a prominent class of the glutathione S-transferases family that is involved in xenobiotic detoxification and antioxidant defense. The full-length complementary DNA of delta-class GST from Penaeus monodon (PmDeltaGST; 839 bp long with a 657 bp coding region) was cloned. The encoded polypeptide of 218 amino acids had a predicted molecular mass of 24.30 kDa. Sequence homology and phylogenetic analysis showed that PmDeltaGST was significant similarity to GST genes in crustaceans and insects. Tissue expression profile analysis by quantitative real-time reverse-transcription polymerase chain showed that PmDeltaGST was constitutively expressed in all the examined tissues, with the highest expression in hepatopancreas and intestine and the weakest expression in ovary. PmDeltaGST messenger RNA expression and protein levels in hepatopancreas was significantly increased at 14 days postexposure of aflatoxin B1 (AFB1), keeping on the high level at 28 days, but decreased at 56 days. The results suggested that PmDeltaGST was involved in the response to AFB1 exposure.

Contraction of the ROS Scavenging Enzyme Glutathione S-Transferase Gene Family in Cetaceans

Cetaceans are a group of marine mammals whose ancestors were adaptated for life on land. Life in an aquatic environment poses many challenges for air-breathing mammals. Diving marine mammals have adapted to rapid reoxygenation and reactive oxygen species (ROS)-mediated reperfusion injury. Here, we considered the evolution of the glutathione transferase (GST) gene family which has important roles in the detoxification of endogenously-derived ROS and environmental pollutants. We characterized the cytosolic GST gene family in 21 mammalian species; cetaceans, sirenians, pinnipeds, and their terrestrial relatives. All seven GST classes were identified, showing that GSTs are ubiquitous in mammals. Some GST genes are the product of lineage-specific duplications and losses, in line with a birth-and-death evolutionary model. We detected sites with signatures of positive selection that possibly influence GST structure and function, suggesting that adaptive evolution of GST genes is important for defending mammals from various types of noxious environmental compounds. We also found evidence for loss of alpha and mu GST subclass genes in cetacean lineages. Notably, cetaceans have retained a homolog of at least one of the genes GSTA1, GSTA4, and GSTM1; GSTs that are present in both the cytosol and mitochondria. The observed variation in number and selection pressure on GST genes suggest that the gene family structure is dynamic within cetaceans.

Experimental models to unravel the molecular pathogenesis, cell of origin and stem cell properties of cholangiocarcinoma

Human cholangiocarcinoma (CCA) is an aggressive tumour entity arising from the biliary tree, whose molecular pathogenesis remains largely undeciphered. Over the last decade, the advent of high-throughput and cell-based techniques has significantly increased our knowledge on the molecular mechanisms underlying this disease while, at the same time, unravelling CCA complexity. In particular, it becomes clear that CCA displays pronounced inter- and intratumoural heterogeneity, which is presumably the consequence of the interplay between distinct tissues and cells of origin, the underlying diseases, and the associated molecular alterations. To better characterize these events and to design novel and more effective therapeutic strategies, a number of CCA experimental and preclinical models have been developed and are currently generated. This review summarizes the current knowledge and understanding of these models, critically underlining their translational usefulness and limitations. Furthermore, this review aims to provide a comprehensive overview on cells of origin, cancers stem cells and their dynamic interplay within CCA tissue.

Participation of liver stem cells in cholangiocarcinogenesis after aflatoxin B1 exposure of glutathione S-transferase A3 knockout mice

Aflatoxin B1, arguably the most potent human carcinogen, induces liver cancer in humans, rats, trout, ducks, and so on, but adult mice are totally resistant. This resistance is because of a detoxifying enzyme, mouse glutathione S-transferase A3, which binds to and inactivates aflatoxin B1 epoxide, preventing the epoxide from binding to DNA and causing mutations. Glutathione S-transferase A3 or its analog has not been detected in any of the sensitive species, including humans. The generation of a glutathione S-transferase A3 knockout (represented as KO or -/-) mice has allowed us to study the induction of liver cancer in mice by aflatoxin B1. In contrast to the induction of hepatocellular carcinomas in other species, aflatoxin B1 induces cholangiocarcinomas in GSTA3-/- mice. In other species and in knockout mice, the induction of liver cancer is preceded by extensive proliferation of small oval cells, providing additional evidence that oval cells are bipolar stem cells and may give rise to either hepatocellular carcinoma or cholangiocarcinoma depending on the nature of the hepatocarcinogen and the species of animal. The recent development of mouse oval cell lines in our laboratory from aflatoxin B1-treated GSTA3-/- mice should provide a new venue for study of the properties and potential of putative mouse liver stem cells.