Effects of Wnt-1 blockade in DEN-induced hepatocellular adenomas of mice

Leaf paste of Telfairia occidentalis favourably modulates deleterious effects associated with exposure to diethylnitrosamine in male Wistar rats

OBJECTIVES

Diethylnitrosamine (DEN) is found in workplaces, processed meats, tobacco smoke, whiskey, etc. It is capable of forming DNA-adducts. Fluted pumpkin (Telfairia occidentalis [To]) is a medicinal plant, and its herbal preparations have been employed variously in ethnomedicine. Furthermore, it has been reported to possess anti-oxidant, anti-cancer, anti-inflammatory properties. We investigated the possible mitigating effect of the leaf paste of To on DEN-induced deleterious effects in male Wistar rats.

METHODS

Forty-five rats weighing between 100 and 150 g were equally divided into nine groups and treated thus: Group 1 (negative control), Group 2 (0.05 mg/kg carboxymethyl cellulose [CMC] daily), Group 3 (positive control, 25 mg/kg bw DEN administered intraperitoneally thrice per week), Group 4 (25 mg/kg bw quercetin [QUE] daily alone), Groups 5 and 6 (100 and 200 mg/kg bw To daily, respectively), Group 7 (25 mg/kg bw DEN and QUE), Groups 8 and 9 (25 mg/kg bw DEN with 100 and 200 mg/kg bw To, respectively). Blood glucose levels, liver damage biomarkers (aspartate aminotransferase [AST], alanine aminotransferase [ALT] and gamma-glutamyltransferase [γ-GT]), frequency of micronucleated polychromatic erythrocyte (mPCEs), and liver histology were assessed.

RESULTS

DEN significantly (p<0.05) increased blood glucose levels, activities of ALT, AST and γ-GT, and frequency of mPCEs. Histologically, DEN caused a severe architectural anarchy. However, the intervention groups demonstrated the remarkable protective properties of To by ameliorating the adverse effects caused by DEN.

CONCLUSIONS

Taken together, the leaf paste of To is capable of mitigating DEN-induced hepatotoxicity and clastogenicity in male Wistar rats.

β-arrestin2 regulating β2-adrenergic receptor signaling in hepatic stellate cells contributes to hepatocellular carcinoma progression

Background: β-arrestin2 and β2-adrenergic receptor (β2-AR) have important roles in malignant tumors, the present study aims to investigate the role of activated β2-AR in hepatic stellate cells (HSCs) during hepatocellular carcinoma (HCC) progression and the regulatory effect of β-arrestin2.

Methods: Immunofluorescence and Western blot were used to detect the expression of β-arrestin2 and β2-AR in HSCs of liver tissues from human HCC samples and diethylnitrosamine (DEN)-induced HCC model mice. We next used β-arrestin2^-/- mice to demonstrate the regulatory role of β-arrestin2 in DEN mice. The subsets of T cells were quantified by flow cytometry. MTT and wound healing assay were applied to detect the proliferation and migration of cells. Co-immunoprecipitation assay was used to detect the link of β-arrestin2 and β2-AR in HSCs. Effect of β-arrestin2 overexpression on β2-AR downstream signaling pathway was verified by Western blot. The secretion of CCL2 was detected by ELISA.

Results: The expression of β2-AR was significantly increased, while β-arrestin2 was decreased in HSCs of HCC tissues. And β-arrestin2 deficiency exacerbates DEN-induced HCC accompanied with increased β2-AR expression. The results of flow cytometry showed that the percentage of activated T cells decreased gradually after DEN injection. β-arrestin2 knockout down-regulated the ratio of activated T cells. In vitro, selective activation of β2-AR in HSCs promoted the proliferation and migration of HCC cells. β-arrestin2 overexpression enhanced co-immunoprecipitation of β-arrestin2 and β2-AR in activated HSCs, and decreased its downstream Akt phosphorylation. Akt inhibitor decreased secretion of CCL2 in activated HSCs.

Conclusion: Our study demonstrated that β2-AR activation in HSCs induces the proliferation and migration of HCC cells may be through Akt signaling, and this effect appears to be regulated by β-arrestin2.

Regulation of Wnt Signaling Pathways at the Plasma Membrane and Their Misregulation in Cancer

Wnt signaling is one of the key signaling pathways that govern numerous physiological activities such as growth, differentiation and migration during development and homeostasis. As pathway misregulation has been extensively linked to pathological processes including malignant tumors, a thorough understanding of pathway regulation is essential for development of effective therapeutic approaches. A prominent feature of cancer cells is that they significantly differ from healthy cells with respect to their plasma membrane composition and lipid organization. Here, we review the key role of membrane composition and lipid order in activation of Wnt signaling pathway by tightly regulating formation and interactions of the Wnt-receptor complex. We also discuss in detail how plasma membrane components, in particular the ligands, (co)receptors and extracellular or membrane-bound modulators, of Wnt pathways are affected in lung, colorectal, liver and breast cancers that have been associated with abnormal activation of Wnt signaling. Wnt-receptor complex components and their modulators are frequently misexpressed in these cancers and this appears to correlate with metastasis and cancer progression. Thus, composition and organization of the plasma membrane can be exploited to develop new anticancer drugs that are targeted in a highly specific manner to the Wnt-receptor complex, rendering a more effective therapeutic outcome possible.

6-Gingerol, a Major Ingredient of Ginger Attenuates Diethylnitrosamine-Induced Liver Injury in Rats through the Modulation of Oxidative Stress and Anti-Inflammatory Activity

Diethylnitrosamine (DEN) is a well-known hepatocarcinogen, and its oral administration causes severe liver damage including cancer. DEN induces the pathogenesis of the liver through reactive oxygen species mediated inflammation and modulation of various biological activities. 6-Gingerol, a major component of ginger, is reported to prevent liver diseases by reducing the oxidative stress and proinflammatory mediators. The present study investigated the hepatoprotective effects of 6-gingerol through the measurement of oxidative stress, anti-inflammatory markers, liver function enzyme parameter, and histopathological analysis. The rats were randomly divided into four groups as the control, DEN treated (50 mg/kg b.w.), DEN+6-gingerol (each 50 mg/kg b.w.), and 6-gingerol only. To evaluate the hepatoprotective effects, liver function enzymes (ALT, AST, and ALP), oxidative stress markers (SOD, GSH, GST, and TAC), lipid peroxidation, inflammatory markers (CRP, TNF-α, IL-6, and ICAM1), haematoxylin and eosin staining, Sirius red staining, immunohistochemistry, and electron microscopy were performed. The results showed a significant increase in liver function enzymes, oxidative stress, and inflammatory markers in the DEN-treated group as compared to the control group. Besides this, altered architecture of hepatocytes (infiltration of inflammatory cells, congestion, blood vessel dilation, and edema), abundant collagen fiber and organelle structures like distorted shaped and swollen mitochondria, and broken endoplasmic reticulum were noticed. The administration of 6-gingerol significantly ameliorated the biochemical and histopathological changes. The increased expression of TNF-α protein was noticed in the DEN-treated group whereas the administration of 6-gingerol significantly decreased the expression of this protein. Based on these findings, it can be suggested that 6-gingerol may be an alternative therapy for the prevention and treatment of liver diseases.

HDAC1/2 Inhibitor Romidepsin Suppresses DEN-Induced Hepatocellular Carcinogenesis in Mice

Background

Hepatocellular carcinoma (HCC) is a frequently diagnosed cancer and a leading cause of cancer-related death worldwide. Its rapid progression, combined with the limited treatment options at late stages, imposes the need for early detection and aggressive intervention. Based on the knowledge that hepatocarcinogenesis is significantly influenced by histone acetylation, we directed our search for novel HCC therapeutics among histone deacetylation inhibitors (HDACi). The aim of the present study was to investigate the effect of HDAC1/2 inhibitor Romidepsin in the well-established mouse model of diethylnitrosamine (DEN)-induced HCC.

Materials and Methods

C56BL/6 mice were treated with Romidepsin at the critical point of 10 months after DEN challenge and their livers were examined 2 months later using histopathology and morphometry. Protein levels were assessed in serum using ELISA and in liver tissues using Western blot and immunohistochemistry (in-situ detection). Gene expression was quantified using real-time PCR.

Results

Romidepsin suppressed cancer progression. This effect was associated with decreased proliferation and increased apoptosis of cancer cells. The cell cycle regulator CK2a, the anti-inflammatory molecule PPAR-γ, and the tumor suppressors PTEN and CYLD were upregulated in treated HCC. By contrast, the expression of PI3K, NF-κB p65 and c-Jun was reduced. In line with this result, the levels of two major apoptosis regulators, ie, BAD and the multifunctional protein c-Met, were lower in the blood serum of treated mice compared to the untreated mice with HCC.

Conclusion

These findings suggest that Romidepsin, a drug currently used in the treatment of lymphoma, could also be considered in the management of early-stage HCC.

Diethylnitrosamine Increases Proliferation in Early Stages of Hepatic Carcinogenesis in Insulin-Treated Type 1 Diabetic Mice

Diethylnitrosamine (DEN) induces hepatocarcinogenesis, increasing mitotic hepatocytes and leading to chronic inflammation. In addition, type 1 diabetes mellitus (T1DM) is also characterized by a proinflammatory state and by requiring insulin exogenous treatment. Given the association of diabetes, insulin treatment, and cell proliferation, our specific goal was to determine whether the liver in the diabetic state presents a greater response to DEN-induced cell cycle alteration, which is essential for the malignant transformation. Male C57BL/6 mice (four-week-old) were divided into 4 groups: C, C + DEN, T1DM, and T1DM + DEN. Mice were euthanized ten weeks after DEN injection. DEN per se produced an increase in liver lipid peroxidation levels. Besides, in T1DM + DEN, we found a greater increase in the proliferation index, in comparison with C + DEN. These results are in agreement with the increased expression observed in cell cycle progression markers: cyclin D1 and E1. In addition, a proapoptotic factor, such as activated caspase-3, evidenced a decrease in T1DM + DEN, while the Vascular Endothelial Growth Factor (VEGF) and the protooncogene p53 showed a higher increase with respect to C + DEN. Overall, the results allow us to highlight a major DEN response in T1DM, which may explain in part the greater predisposition to the development of hepatocarcinoma (HCC) during the diabetic state.