Discovery of CYP2E1 as a novel target in rheumatoid arthritis and validation by a new specific CYP2E1 inhibitor

Considerable evidence indicates that CYP2E1 is associated with a variety of inflammatory diseases. Here we evaluated CYP2E1 as a potential therapeutic target for rheumatoid arthritis (RA) and established the protective effect of a new CYP2E1 inhibitor. Gene-expression datasets were used to analyze the change in expression of CYP2E1 in RA patients; CYP2E1 activity in collagen-induced arthritis (CIA) rats was determined by HPLC. We further evaluated the protective effects of Cyp2e1 knockout and a CYP2E1-specific inhibitor, Q11, synthesized by our group, in CIA and adjuvant-induced arthritis (AIA) rats. The expression of CYP2E1 in synovial tissue was elevated in RA patients and in CIA rats and the activity of CYP2E1 in vivo and in vitro in CIA rats was greater than that of controls. Cyp2e1 knockout significantly reduced the incidence of CIA and alleviated the severity of symptoms. Treatment with different doses of Q11 decreased paw thickness, volume and arthritis scores and reduced the serum levels of IL-6, TNF-α, IL-1β and MDA, and increased the level of GSH in CIA rats. A similar inhibitory effect was exhibited for Q11 in the AIA rats. Moreover, Q11 significantly impeded proliferation, migration, and invasion of human rheumatoid arthritis synovial fibroblasts cells. Q11 decreased the release of ROS and enhanced Nrf2 nuclear translocation and HO-1 expression in the cell nucleus. Overall, our results indicated that CYP2E1 may be a new target for RA and Q11 has potential protective effects against RA by reducing oxidative stress and opposing the inflammatory response via the ROS/Nrf2/HO-1 signaling pathway.

Past, present, and future of chemically induced hepatocarcinogenesis rodent models: Perspectives concerning classic and new cancer hallmarks

Hepatocellular carcinoma (HCC), the main primary liver cancer, accounts for 5 % of all incident cases and 8.4 % of all cancer-related deaths worldwide. HCC displays a spectrum of environmental risk factors (viral chronic infections, aflatoxin exposure, alcoholic- and nonalcoholic fatty liver diseases) that result in molecular complexity and heterogeneity, contributing to a rising epidemiological burden, poor prognosis, and non-satisfactory treatment options. The emergence of HCC (i.e., hepatocarcinogenesis) is a multistep and complex process that addresses many (epi)genetic alterations and phenotypic traits, the so-called cancer hallmarks. "Polymorphic microbiomes", "epigenetic reprogramming", "senescent cells" and "unlocking phenotypic plasticity" are trending hallmarks/enabling features in cancer biology. As the main molecular drivers of HCC are still undruggable, chemically induced in vivo models of hepatocarcinogenesis are useful tools in preclinical research. Thus, this narrative review aimed at recapitulating the basic features of chemically induced rodent models of hepatocarcinogenesis, eliciting their permanent translational value regarding the "classic" and the "new" cancer hallmarks/enabling features. We gathered state-of-art preclinical evidence on non-cirrhotic, inflammation-, alcoholic liver disease- and nonalcoholic fatty liver-associated HCC models, demonstrating that these bioassays indeed express the recently added hallmarks, as well as reflect the interplay between classical and new cancer traits. Our review demonstrated that these protocols remain valuable for translational preclinical application, as they recapitulate trending features of cancer science. Further "omics-based" approaches are warranted while multimodel investigations are encouraged in order to avoid "model-biased" responses.

Identification of Cytochrome P450 2E1 as a Novel Target in Glioma and Development of Its Inhibitor as an Anti-Tumor Agent

Glioblastoma (GBM) is a devastating inflammation-related cancer for which novel therapeutic targets are urgently required. Previous studies of the authors indicate Cytochrome P450 2E1 (CYP2E1) as a novel inflammatory target and develop a specific inhibitor Q11. Here it is demonstrated that CYP2E1 overexpression is closely related to higher malignancy in GBM patients. CYP2E1 activity is positively correlated with tumor weight in GBM rats. Significantly higher CYP2E1 expression accompanied by increased inflammation is detected in a mouse GBM model. Q11, 1-(4-methyl-5-thialzolyl) ethenone, a newly developed specific inhibitor of CYP2E1 here remarkably attenuates tumor growth and prolongs survival in vivo. Q11 does not directly affect tumor cells but blocks the tumor-promoting effect of microglia/macrophage (M/Mφ) in the tumor microenvironment through PPARγ-mediated activation of the STAT-1 and NF-κB pathways and inhibition of the STAT-3 and STAT-6 pathways. The effectiveness and safety of targeting CYP2E1 in GBM are further supported by studies with Cyp2e1 knockout rodents. In conclusion, a pro-GBM mechanism in which CYP2E1-PPARγ-STAT-1/NF-κB/STAT-3/STAT-6 axis fueled tumorigenesis by reprogramming M/Mφ and Q11 as a promising anti-inflammatory agent for GBM treatment is uncovered.

The CYP2E1 inhibitor Q11 ameliorates LPS-induced sepsis in mice by suppressing oxidative stress and NLRP3 activation

Sepsis is an infection-induced, multi-organ system failure with a pathophysiology related to inflammation and oxidative stress. Increasing evidence indicates that cytochrome P450 2E1 (CYP2E1) is involved in the incidence and development of inflammatory diseases. However, a role for CYP2E1 in lipopolysaccharide (LPS)-induced sepsis has not been completely explored. Here we use Cyp2e1 knockout (cyp2e1-/-) mice to determine if CYP2E1 could be a therapeutic target for sepsis. We also evaluated the ability of Q11, a new specific CYP2E1 inhibitor, to prevent and ameliorate LPS-induced sepsis in mice and in LPS-treated J774A.1 and RAW264.7 cells. Cyp2e1 deletion significantly reduced hypothermia, multi-organ dysfunction and histological abnormalities in LPS-treated mice; consistent with this finding, the CYP2E1 inhibitor Q11 significantly prolonged the survival time of septic mice and ameliorated multi-organ injury induced by LPS. CYP2E1 activity in liver correlated with indicators of multi-organ injury, such as the level of lactate dehydrogenase (LDH) and blood urea nitrogen (BUN) (P<0.05). Q11 significantly suppressed the expression of NLRP3 in tissues after LPS injection; in vitro studies revealed that activation of NLRP3 signaling and increase of ROS was attenuated by Q11 in LPS-stimulated macrophages, which was reflected by reduced expression of caspase-1 and formation of ASC specks. Overall, our results indicate that Q11 improves the survival of mice with LPS-induced sepsis and attenuates sepsis-induced multiple-organ injury, suggesting that CYP2E1 could be a therapeutic target for sepsis.

An iron-deficient diet prevents alcohol- or diethylnitrosamine-induced acute hepatotoxicity in mice by inhibiting ferroptosis

The liver is easily injured by exogenous chemicals through reactive oxygen species (ROS), which lead to ferroptosis, a ROS-dependent programmed cell death characterized by iron accumulation and lipid peroxidation. However, whether iron restriction has a positive role in chemicals-induced liver injuries is unknown. The present study investigated the effects of an iron-deficient diet on liver injuries induced by alcohol or diethylnitrosamine (DEN). Mice were fed an iron-deficient diet for four weeks, then treated with three doses of alcohol (5 g/kg, 24 h interval, gavage) to mimic mild liver injury or five doses of DEN (50 mg/kg, 24 h interval, i. p.) to mimic severe liver failure. The results showed that mice were iron-deficient after four weeks of feeding. Interestingly, as evaluated by H&E staining of liver slices, liver/body weight ratio, serum ALT and AST, iron deficiency significantly alleviated liver injuries triggered by alcohol or DEN. The activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), and the expression of CYP2E1 were increased by iron deficiency. Mechanistically, iron deficiency prevented the decrease of glutathione peroxidase 4 (GPX4), which eliminated malondialdehyde (MDA) by utilizing glutathione (GSH). In summary, alcohol- or DEN-induced liver injuries were mitigated by the iron-deficient diet by inhibiting ferroptosis, which might be a promising measure for preventing liver injuries induced by alcohol, DEN, or other exogenous chemicals.

The effect of aging on the repeated-dose liver micronucleus assay using diethylnitrosamine

Background

The repeated-dose liver micronucleus (RDLMN) assay has been well-developed and applied because of its simplicity and the ease of integration into general toxicity studies which is the preferred method from the 3R’s point of view. In this assay, we observed micronucleated hepatocytes which accumulated during a rather long-term dosing period. When considering integration into general toxicity studies, the effects of age of the animals used in the micronucleus assay becomes a major issue. The effect of age on the micronucleus induction rate has been reported in bone marrow micronucleus assays, and it is considered that the decrease in cell proliferation rate due to aging is the cause of the decrease in sensitivity. A decrease in sensitivity due to aging was also reported in a liver micronucleus assay using clofibrate and the cause is considered to be a decrease in hepatocyte proliferation activity due to aging. However, no actual decrease in hepatocyte proliferation rate due to aging has been reported. In addition, there are no reports, so far, on whether similar effects of aging appear when other substances were administered. To investigate the effects of aging in the RDLMN assay, this study focused on the effects of 14-day repeated administration of DEN, a well-known genotoxic hepatocarcinogen with the hepatocyte toxicity which should cause an elevation of cell proliferation rate as a reflective regeneration.

Results

The liver micronuclei induced by DEN were equivalent between the two age groups (i.e., six and eight weeks of age at the start of dosing). In the histopathological examination for the liver, single cell necrosis, karyomegaly, and increased mitosis were observed in the hepatocytes, and the frequency and severity were increased dose-dependently. Ki-67 immunohistochemical analysis which can detect all cells in the cell cycle other than those in the G0 phase revealed dose-dependent increase of cell proliferation activity, and the difference between ages was not observed.

Conclusion

The effect of aging on the RDLMN assay could not be recognized when DEN was administered for 14 days in rats. Meanwhile, it was supported by the histopathological examination and Ki-67 immunohistochemical analysis that such an effect of aging was masked by the compensatory hepatocyte proliferation which was induced by the hepatocyte toxicity of DEN.

The POR rs10954732 polymorphism decreases susceptibility to hepatocellular carcinoma and hepsin as a prognostic biomarker correlated with immune infiltration based on proteomics

The effect of the cytochrome P450 oxidoreductase (POR) rs10954732 (G > A) polymorphism on hepatocellular carcinoma (HCC) susceptibility is unknown. Here we found that A allele carriers showed a 69% decrease in susceptibility to HCC with overall survival (OS) prolonged to 199%, accompanied by lower activity for cytochrome P450 2E1. A total of 222 differentially expressed proteins were mainly enriched in neutrophil and T cell activation and involved in the immune and inflammatory responses, constituting the altered immune tumor microenvironment related with A allele by proteomics analysis. Hepsin (HPN) showed significant down-regulation in HCC and up-regulation in A allele carriers. A lower HPN level was associated with increased susceptibility to HCC and a worse prognosis. Moreover, HPN is a potential independent prognostic biomarker for HCC and is strongly associated with clinicopathological features, tumor-infiltrating status of immune cells both in our discovery cohort and database surveys. Our findings provide a new potential mechanism by which HPN may play an important role in the susceptibility of rs10954732 A allele carriers to HCC and their prognosis through tumor immune infiltration, thus offering potential insights for future studies on tumor immunotherapy.

Stat4 rs7574865 polymorphism promotes the occurrence and progression of hepatocellular carcinoma via the Stat4/CYP2E1/FGL2 pathway

Although there are many studies on the relationship between genetic polymorphisms and the incidence of diseases, mechanisms are rarely known. We report the mechanism by which signal transducer and activator of transcription 4 (stat4) rs7574865 promotes the occurrence and progression of hepatocellular carcinoma (HCC). We found that the GG genotype at stat4 rs7574865 was a risk genotype, and STAT4 levels in serum and peritumoral tissue from HCC patients with the GG genotype were significantly higher than those found in TT or TG carriers. Furthermore, HCC patients with the GG genotype or elevated STAT4 levels had poor prognoses. In vitro experiments demonstrated that STAT4 silencing promoted apoptosis and inhibited the invasion and migration of HepG2 and L02 cells. Proteomic analysis of HCC peritumors identified 273 proteins related to STAT4, of which CYP2E1 activity and FGL2 content exhibited the highest positive correlation. The relationship between CYP2E1 and FGL2 was also confirmed in cyp2e1^−/− mice and in CYP2E1 inhibitor-treated mice. In conclusion, this study elucidates the mechanism by which the stat4 rs7574865 polymorphism promotes the occurrence and progression of HCC via the Stat4/CYP2E1/FGL2 pathway.

The proteomic characterization of the peritumor microenvironment in human hepatocellular carcinoma

The tumor microenvironment (TME) was usually studied in tumor tissue and in relation to only tumor progression, with little involved in occurrence, recurrence and metastasis of tumor. Thus, a new concept "peritumor microenvironment (PME)" was proposed in the proteomic characterization of peritumor liver tissues in human hepatocellular carcinoma (HCC). The PME for occurrence (PME-O) and progression (PME-P) were almost totally different at proteome composition and function. Proteins for occurrence and progression rarely overlapped and crossed. Immunity played a central role in PME-O, whereas inflammation, angiogenesis and metabolism were critical in PME-P. Proteome profiling identified three PME subtypes with different features of HCC. Thymidine phosphorylase (TYMP) was validated as an antiangiogenic target in an orthotopic HCC mouse model. Overall, the proteomic characterization of the PME revealed that the entire processes of HCC occurrence and progression differ substantially. These findings could enable advances in cancer biology, diagnostics and therapeutics.

In Vivo and In Vitro Models of Hepatocellular Carcinoma: Current Strategies for Translational Modeling

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and the third leading cause of cancer-related death globally. HCC is a complex multistep disease and usually emerges in the setting of chronic liver diseases. The molecular pathogenesis of HCC varies according to the etiology, mainly caused by chronic hepatitis B and C virus infections, chronic alcohol consumption, aflatoxin-contaminated food, and non-alcoholic fatty liver disease associated with metabolic syndrome or diabetes mellitus. The establishment of HCC models has become essential for both basic and translational research to improve our understanding of the pathophysiology and unravel new molecular drivers of this disease. The ideal model should recapitulate key events observed during hepatocarcinogenesis and HCC progression in view of establishing effective diagnostic and therapeutic strategies to be translated into clinical practice. Despite considerable efforts currently devoted to liver cancer research, only a few anti-HCC drugs are available, and patient prognosis and survival are still poor. The present paper provides a state-of-the-art overview of in vivo and in vitro models used for translational modeling of HCC with a specific focus on their key molecular hallmarks.

Standardization of diethylnitrosamine-induced hepatocellular carcinoma rat model with time based molecular assessment

This study was intended (1) to develop a robust animal model for hepatocellular carcinoma (HCC) research, in which HCC tumors develop in a background of fibrosis or cirrhosis; and (2) to explore time-dependent regulatory changes in key molecular markers during disease advancement and HCC development. With the aim of establishing such HCC model, male Sprague-Dawley rats were injected with diethylnitrosamine (DEN) at a dose of 30 mg/kg twice a week for 10 weeks then once a week from 12th to 16th weeks. The rats were kept under observation until 18th week. At defined time intervals (2nd, 4th, 12th, and 18th week), serum biomarkers and microscopic components of tissue samples were used to investigate the chronic progression of liver disease, while gene and protein analysis was used to monitor expression patterns during HCC development. DEN-intoxicated rats manifested inflammation at week 4, fibrosis at week 12 and cirrhosis with early HCC tumors at week 18. Molecular analysis revealed that key markers of inflammation (Il-1β, Il-6, and Tnf-α), fibrosis (Tgf-β1, Col1α1, Col3α1, and Timp-1), and angiogenesis (Hif1-α and Vegf) were promptly (P ≤ 0.001) up-regulated at week 4, week 12 and week 18, respectively. Oxidative stress (iNos, Cyp2e1, and Sod1) and pro-apoptotic (Bax) markers showed significant upregulation from week 4 to week 12. However, Sod1 and Bax expressions dropped after week 12 and reached a minimum at 18th week. Strikingly, expressions of anti-apoptotic (Bcl-2) and cell proliferation (Pcna, Hgf, and Afp) markers were abruptly increased at week 18. Collectively, we describe an 18-week HCC model in DEN-intoxicated rats that exhibit chronic inflammation, oxidative imbalance, advance fibrosis/cirrhosis, halted apoptosis, and angiogenic sprouting, progressively.

Use of proteomics to identify mechanisms of hepatocellular carcinoma with the CYP2D6*10 polymorphism and identification of ANGPTL6 as a new diagnostic and prognostic biomarker

BACKGROUND

Although an association between the cytochrome P4502D6 (CYP2D6) *10 (100C>T) polymorphism and hepatocellular carcinoma (HCC) is known, the mechanism remains unclear. Here we aimed to explore mechanisms of CYP2D6*10 (100C>T) polymorphism conferring to HCC, and screen markers for HCC.

METHODS

Label-free global proteome profiling with 34 normal livers and peritumor tissue from 61 HCC patients was performed, and angiopoietin-like protein-6 (ANGPTL6) was evaluated in 2 liver samples validation cohorts and 2 blood specimens validation cohorts.

RESULTS

We found a significantly decreased frequency of TT in HCC patients which reduced HCC susceptibility by 69.2% and was accompanied by lowered enzymatic activity for CYP2D6. Proteomic analysis revealed 1342 differentially expressed proteins (DEPs) that were associated with HCC and 88 DEPs were identified as 100 TT-related proteins, likely underlying the susceptibility to HCC. Twenty-two upregulated DEPs and 66 downregulated DEPs were mainly related to lipid metabolism and the extracellular matrix, respectively. High ANGPTL6 was associated with a higher risk to HCC and worse prognosis. ANGPTL6 was both an independent risk factor and an independent prognostic factor for HCC and exhibited strong potential for predicting HCC occurrence, with comparable AUC values and higher sensitivity compared with alpha-fetoprotein.

CONCLUSIONS

The TT genotype-associated decreased risk of HCC appears to be related to lowered CYP2D6 activity and altered protein expression in the tumor microenvironment, and ANGPTL6 is a promising new diagnostic and prognostic biomarker for HCC. Our findings reveal new mechanistic insights for polymorphisms related to HCC risk and provide avenues for screening for HCC.

Ferulic acid prevents aflatoxin B1-induced liver injury in rats via inhibiting cytochrome P450 enzyme, activating Nrf2/GST pathway and regulating mitochondrial pathway

Aflatoxin B1 (AFB1) causes oxidative stress and hepatocyte apoptosis through its epoxidized metabolite AFBO, which is catalyzed by CYP450 enzymes. Ferulic acid (FA) is a phenolic acid commonly found in plants and is known for its antioxidant capacity. However, the role of FA in AFB1-induced liver injury is still elusive. In this study, rats were exposed to AFB1 and simultaneously treated with FA for 30 days. The results showed that I) FA alleviated the histopathological changes induced by AFB1, inhibited the elevation of serological indexes induced by AFB1, and reduced the production of AFBO in liver. II) AFB1-induced increase in CYP450 expression was significantly reduced by FA. The molecular docking results of FA and CYP2A6 showed high fitness score and interaction. III) FA obviously inhibited the production of MDA, and significantly activated the Nrf2/GST pathway and antioxidant enzymes (SOD and GST). IV) AFB1-induced hepatocyte apoptosis, the high expression of p53, bax, cyt-c, caspase-9, caspase-3, and the low expression of bcl-2 were all restored by FA. It has been suggested from these results that FA proved effective against AFB1-induced liver damage in rats via inhibiting CYP450 enzyme, promoting antioxidant pathway Nrf2/GST, activating antioxidant enzymes (SOD and GST), and regulating the mitochondrial pathway.

CD276 Promotes Vasculogenic Mimicry Formation in Hepatocellular Carcinoma via the PI3K/AKT/MMPs Pathway

Purpose

CD276 protein expression and vasculogenic mimicry (VM) formation are associated with the poor prognosis of hepatocellular carcinoma (HCC) patients. Although both the effects of CD276 and VM formation involve the activation of matrix metalloproteinases, and their relationship has not yet been explored. The following study investigated the effect of CD276 expression on VM formation and the potential mechanisms.

Materials and Methods

CD276 expression and VM were examined in commercial tissue microarrays by immunohistochemistry and CD31/PAS double staining. Tumor cell proliferation, invasion, migration and, tube formation were detected in vitro after transfecting HCC cell lines with an shRNA lentiviral vector against CD276. The expression of MMP14, MMP2, VE-cadherin, E-cadherin, and vimentin and MMPs activation was detected by Western blot, immunofluorescence and gelatin zymography assay. In addition, an orthotopic xenograft model of HCC cells was established in vivo, after which VM was detected, along with its marker molecules.

Results

CD276 expression was associated with VM and poor prognosis in HCC patients. RNA interference of CD276 reduced tumor cell proliferation, invasion, migration, and VM formation in vitro and in vivo. Furthermore, CD276 knockdown up-regulated the expression of E-cadherin but inhibited the phosphorylation of AKT, the expression of MMP14, MMP2, VE-cadherin, vimentin and the activation of MMP2 and MMP9 in HCC cell lines.

Conclusion

CD276 may promote VM formation by activating the PI3K/AKT/MMPs pathway and inducing the EMT process in HCC. CD276 may serve as a promising candidate for the anti-VM treatment of HCC.

Ascorbic acid prevents N-nitrosodiethylamine-induced hepatic injury and hepatocarcinogenesis in Akr1a-knockout mice

To gain insights into the benefits of ascorbic acid (AsA) in hepatoprotection, we examined the status of Akr1a^-/- (KO) mice, which biosynthesize AsA at about 10% the rate as Akr1a^+/+ (WT) mice, in terms of their response to an N-nitrosodiethylamine (NDEA)-induced hepatic injury. The intraperitoneal injection of NDEA (35 mg/kg) started at 4 weeks of age and was performed at weekly intervals thereafter. While the fatality rate was substantial in the KO mice, AsA supplementation (1.5 mg/ml in the drinking water) greatly extended their life-spans. Only two out of 54 KO mice survived to 28 weeks, and both contained approximately an order of magnitude greater number of tumor nodules compared to WT mice or KO mice with AsA supplementation. Histological and biochemical examinations at 20 weeks indicated that AsA potently protected against the hepatotoxic action of NDEA. Interestingly, the AsA levels in the liver were higher in the AsA-supplemented KO mouse groups that had received the NDEA treatment compared to the corresponding control group. While the protein levels of Cyp2e1, an enzyme that plays a major role in the bioactivation of NDEA, had declined to a similar extent among the experimental groups, p-nitrophenol-oxidizing activity was sustained at high levels in the KO mouse livers but AsA supplementation suppressed this activity. These findings confirm that AsA is a potent micronutrient that copes with hepatic injury and cancer development caused by exposure to NDEA in the livers of Akr1a-knockout mice.

Chondroitin-modified lipid nanoparticles target the Golgi to degrade extracellular matrix for liver cancer management

Liver cancer is a serious liver disease in which hepatoma cells and activated hepatic stellate cells (HSCs) overproduce extracellular matrix (ECM), which involves the Golgi apparatus. Here chondroitin-modified lipid nanoparticles (CSNs) were prepared and loaded with doxorubicin (DOX) and retinoic acid (RA) using a thin-film hydration-high pressure homogenization method. The resulting DOX + RA-CSNs were efficiently taken up by SMMC-7721 hepatoma cells and HSCs in culture, where they accumulated in the Golgi apparatus and destroyed it, inhibiting ECM production. Injecting DOX + RA-CSNs into mice with primary liver cancer or H22 allografts led to significantly higher tumor penetration by DOX and RA, greater antitumor efficacy, and lower DOX-related toxicity than injecting a solution of the two drugs. Immunofluorescence and immunohistochemistry of liver tissues showed that DOX + RA-CSNs dramatically reduced expression of the ECM components. These results suggest that CSNs show potential for targeting drugs to the Golgi apparatus of liver cancer cells and potentially other types of tumors.

Metabolism of N-nitrosodimethylamine, methylation of macromolecules, and development of hepatic fibrosis in rodent models

Hepatic fibrosis and cirrhosis are chronic diseases affecting liver and a major health problem throughout the world. The hallmark of fibrosis and cirrhosis is inordinate synthesis and deposition of fibril forming collagens in the extracellular matrix of the liver leading to nodule formation and loss of normal architecture. Hepatic stellate cells play a crucial role in the pathogenesis and progression of liver fibrosis through secretion of several potent fibrogenic factors that trigger hepatocytes, portal fibrocytes, and bone marrow-derived fibroblasts to synthesize and deposit several connective tissue proteins, especially collagens between hepatocytes and space of Disse. Regulation of various events involved in the activation and transformation of hepatic stellate cells seems to be an appropriate strategy for the arrest of hepatic fibrosis and liver cirrhosis. In order to unravel the molecular mechanisms involved in the pathogenesis and progression of hepatic fibrosis, to determine proper and potent targets to arrest fibrosis, and to discover powerful therapeutic agents, a quick and reproducible animal model of hepatic fibrosis and liver cirrhosis that display all decompensating features of human condition is required. This review thoroughly evaluates the biochemical, histological, and pathological features of N-nitrosodimethylamine-induced model of liver injury, hepatic fibrosis, and early cirrhosis in rodents.

Dendrimer-conjugated podophyllotoxin suppresses DENA-induced HCC progression by modulation of inflammatory and fibrogenic factors

Podophyllotoxin has been explored as an anticancer, antiviral, and antibacterial agent; however, its low water solubility and toxicity limit its use. In this study, the efficacy of a more soluble and less toxic polyamidoamine (PAMAM) dendrimer-conjugated podophyllotoxin (DPODO) was evaluated against chemically induced hepatocellular carcinoma (HCC) in mice. HCC was induced by giving 0.01% diethylnitrosamine (DENA) in drinking water for 16 weeks. The HCC-induced mice were treated with 10 or 20 mg per kg body weight DPODO. The DENA administration led to HCC development, characterized by anisocytosis, karyomegaly, inflammation and degenerative changes in the liver. The DPODO treatment at 10 mg and 20 mg doses significantly reduced the histopathological changes in liver tissue. The DPODO treatment also significantly lowered the levels of inflammatory markers IL-6 and NF-κB in serum and tissue, respectively. Further, the treatment also significantly reduced fibrous tissue deposition in the liver, which was further confirmed by the reduced mRNA levels and tissue expression of fibrogenic markers TGF-β and α-SMA in the liver. The results of the present study indicate that DPODO treatment suppresses the progression of HCC by modulating the inflammatory and fibrogenic factors, which play important roles in HCC development.

Molecular mechanisms in the pathogenesis of N-nitrosodimethylamine induced hepatic fibrosis

Hepatic fibrosis is marked by excessive synthesis and deposition of connective tissue proteins, especially interstitial collagens in the extracellular matrix of the liver. It is a result of an abnormal wound healing in response to chronic liver injury from various causes such as ethanol, viruses, toxins, drugs, or cholestasis. The chronic stimuli involved in the initiation of fibrosis leads to oxidative stress and generation of reactive oxygen species that serve as mediators of molecular events involved in the pathogenesis of hepatic fibrosis. These processes lead to cellular injury and initiate inflammatory responses releasing a variety of cytokines and growth factors that trigger activation and transformation of resting hepatic stellate cells into myofibroblast like cells, which in turn start excessive synthesis of connective tissue proteins, especially collagens. Uncontrolled and extensive fibrosis results in distortion of lobular architecture of the liver leading to nodular formation and cirrhosis. The perpetual injury and regeneration process could also results in genomic aberrations and mutations that lead to the development of hepatocellular carcinoma. This review covers most aspects of the molecular mechanisms involved in the pathogenesis of hepatic fibrosis with special emphasize on N-Nitrosodimethylamine (NDMA; Dimethylnitorsmaine, DMN) as the inducing agent.