Smad3 phospho-isoform signaling in hepatitis C virus-related chronic liver diseases

Astragaloside IV suppresses migration and invasion of TGF-β1-induced human hepatoma HuH-7 cells by regulating Nrf2/HO-1 and TGF-β1/Smad3 pathways

Astragaloside IV (AS-IV), one of the major compounds extract from Astragalus membranaceus, has shown attractive anti-cancer effects in certain malignancies. Oxidative stress (OS) is considered as a crucial factor in promoting the progression of hepatocellular carcinoma (HCC). In response to OS, nuclear factor erythroid 2-related factor 2 (Nrf2) upregulates and induces heme oxygenase 1 (HO-1) to combat oxidative damages. The phosphorylation of the COOH-terminal of Smad3 (pSmad3C) activates p21 to resist HCC progression, while the phosphorylation of the linker region of Smad3 (pSmad3L) up-regulates c-Myc transcription to exert promoting effect towards HCC. This study aimed to explore whether AS-IV suppresses migration and invasion of human hepatoma HuH-7 cells by regulating Nrf2/HO-1 and TGF-β₁/Smad3 pathways. HuH-7 cells were induced with TGF-β₁ (9 or 40 pM) to establish HCC model in vitro and pretreated with AS-IV at different concentration (5, 10, and 20 μM) for 24 h. Cell proliferation, migration, invasion, and intracellular reactive oxygen species (ROS) of HuH-7 cells were measured. The expression of Nrf2, pSmad3C, Nrf2/pNrf2, HO-1, pSmad3C/3L, c-Myc, and p21 were detected. Exposure of HuH-7 cells to TGF-β₁ enhanced the cell proliferation, migration, invasion, and ROS production. Pretreatment with AS-IV (5, 10, and 20 μM) significantly reduced the cell proliferation, migration, invasion, and ROS production in HuH-7 cells. Furthermore, AS-IV increased the expressions of Nrf2/pNrf2, HO-1, pSmad3C, and p21, meanwhile reduced the expressions of pSmad3L and c-Myc. In conclusion, our study suggested that AS-IV inhibit HuH-7 cells migration and invasion, which related to activate Nrf2/HO-1 pathway, up-regulation pSmad3C/p21 pathway, and down-regulation pSmad3L/c-Myc pathway. The present research supports the notion that AS-IV may be a latent agent for the treatment of HCC.

Role of phosphorylated Smad3 signal components in intraductal papillary mucinous neoplasm of pancreas

BACKGROUND

Malignant intraductal papillary mucinous neoplasm (IPMN) has poor prognosis. The carcinogenesis of IPMN is not clear. The aim of this study was to clarify transitions in phosphorylated Smad3 signaling during IPMN carcinogenesis.

METHODS

By using immunohistochemistry, we examined the expression of pSmad3C and pSmad3L from 51 IPMN surgical specimens resected at our institution between 2010 and 2013. We also examined the expression of Ki-67, c-Myc and p-JNK.

RESULTS

The median immunostaining index of pSmad3C was 79.2% in low-grade dysplasia, 74.9% in high-grade dysplasia, and 42.0% in invasive carcinoma (P < 0.01), whereas that of pSmad3L was 3.4%, 4.3%, and 42.4%, respectively (P < 0.01). There was a negative relationship between the expression of pSmad3C and c-Myc (P < 0.001, r = -0.615) and a positive relationship between the expression of pSmad3L and c-Myc (P < 0.001, r = 0.696). Negative relationship between the expression of pSmad3C and Ki-67 (P < 0.01, r = -0.610) and positive relationship between the expression of pSmad3L and Ki-67 (P < 0.01, r = 0.731) were confirmed. p-JNK-positive cells were frequently observed among pSmad3L-positive cancer cells. The median of pSmad3L/pSmad3C ratio in the non-recurrence group and the recurrence group were 0.58 (range, 0.05-0.93), 3.83 (range, 0.85-5.96), respectively (P = 0.02). The median immunostaining index of c-Myc in the non-recurrence group and the recurrence group were 2.91 (range, 0-36.9) and 82.1 (range, 46.2-97.1), respectively (P = 0.02). The median immunostaining index of Ki-67 in the non-recurrence group and the recurrence group were 12.9 (range 5.7-30.8) and 90.9 (range 52.9-98.5), respectively (P = 0.02).

CONCLUSIONS

pSmad3L was upregulated in malignant IPMN. pSmad3L/pSmad3C ratio may be a useful prognostic factor in IPMN.

Stevia prevents experimental cirrhosis by reducing hepatic myofibroblasts and modulating molecular profibrotic pathways

AIM

The aims of the present study were to investigate the capacity of stevia leaves to prevent experimental cirrhosis induced by chronic administration of carbon tetrachloride (CCl₄ ) in rats and to explore the action mechanism involved.

METHODS

Liver cirrhosis was established by CCl₄ treatment (400 mg/kg i.p. three times a week for 12 weeks); stevia powder was administered (100 mg/kg by gavage daily) during the CCl₄ treatment. Serum markers of liver damage and hydroxyproline were evaluated and histopathological analyses were carried out. The profibrotic pathways were analyzed by western blot and immunohistochemistry.

RESULTS

We found for the first time that stevia cotreatment prevented the elevation of serum markers of necrosis and cholestasis and the occurrence of liver fibrosis. It is worth noting that stevia downregulated several profibrogenic pathways, including the reduction of hepatic myofibroblasts and decreased matrix metalloproteinase (MMP)2 and MMP13 expression, thereby blocking the liberation of transforming growth factor-β from the extracellular matrix. Notably, stevia reduced the phosphorylation of pSmad3L, the most profibrogenic and mitogenic Smad, by inhibiting the activation of c-Jun N-terminal kinase and extracellular signal-regulated kinase. Interestingly, Smad7, an important antifibrotic molecule, was upregulated by stevia treatment in cirrhotic rats. These multitarget mechanisms led to the prevention of experimental cirrhosis.

CONCLUSIONS

Because stevia possesses a reasonable safety profile, our results indicate that it could be useful in the clinical setting to treat chronic liver diseases.

Significance of pSmad2/3 and Smad4 in hepatitis C virus-related liver fibrosis and hepatocellular carcinoma

Chronic hepatitis C (CHC) is a major public health problem, especially in Egypt. Risk of hepatocellular carcinoma (HCC) development increases as hepatitis C virus (HCV)-related liver diseases progress. Smads act as substrates for the transforming growth factor-beta (TGF-β) family of receptors. This study aims to assess hepatic expression of pSmad2/3 and Smad4 in CHC with different stages of fibrosis and grades of necro-inflammation as well as in HCC on top of CHC. This study was done on 33 core liver biopsies from patients with CHC (15 with early fibrosis and 18 with late fibrosis), 15 liver specimens from HCC cases on top of CHC, as well as five normal controls. pSmad2/3 and Smad4 show more immunopositivity, higher percentage of positive hepatocytes and stronger staining intensity in CHC with late fibrosis compared to early fibrosis. pSmad2/3 shows increase of the previous parameters in CHC with high grade activity than those with low activity. Smad4 shows increase of the previous parameters in HCC compared to CHC cases. pSmad2/3 and Smad4 can be used as diagnostic and/or prognostic markers for progression of HCV-related fibrosis to cirrhosis and further progression to HCC.

Exploring the associations of host genes for viral infection revealed by genome-wide RNAi and virus–host protein interactions

Genome-wide RNA interference screens have greatly facilitated the identification of essential host factors (EHFs) for viral infections, whose knockdown effects significantly influence virus replication but not host cell viability.