Effect of Smad7 deficiency on rat cardiac fibroblasts proliferation, migration, cell differentiation and collagen I secretion in vitro / 解剖学报

Objective To investigate the effects of Smad7 knock down by lentivirus on rat cardiac fibroblasts proliferation, migration, cell differentiation and collagen secretion in vitro. Methods The primary cardiac fibroblasts were separated from the hearts of ten SD rats and identified by immunohistochemical method. The lentivirus transfection knocked down the expresson of Smad7 in cardiac fibroblasts, Western blotting was used to detect the efficiency of Smad7 knock down by lentivirus. The proliferation of cardiac fibroblasts was quantified by real-time unlabeled cell analyzer. Cell migration was evaluted by cell wound scratch assay. Western blotting was used to detect expression of α-smooth muscle actin（α-SMA） and collagen Ⅰ（Col Ⅰ）. Results Myocardial fibroblasts were successfully cultured and identified by immunocytochemical methods. The multiplicity of infection（MOI） that lentivirus transduction of myocardial fibroblasts was 100. After lentivirus transduction, 88.33% myocardial fibroblasts expressed green fluorescent protein, showed that the lentivirus could significantly reduce the protein expression of Smad7. Smad7 deficiency decreased the proliferation and migration of cardiac fibroblasts, increased the protein expression of α-SMA and decreased collagen secretion. The results indicated that Smad7 deficiency significantly down-regulated the proliferation and migration of cardiac fibroblasts, increased α-SMA protein expression and reduced ColⅠ protein expression. Conclusion Smad7 deficiency can significantly change the cardiac fibroblasts function, that is related to the pathological mechanism that lead to myocardial fibrosis

Premalignant alteration assessment in liver-like tissue derived from embryonic stem cells by aristolochic acid I exposure.

The in vitro predictive evaluation of chemical carcinogenicity based on hepatic premalignance has so far not been established. Here, we report a novel approach to investigate the premalignant events triggered by human carcinogen aristolochic acid I (AAI) in the liver-like tissue derived from mouse embryonic stem cells. By AAI exposure, the liver-like tissue exhibited the paracrine interleukin-6 phenotypic characteristics. Hepatocytes expressed STAT3/p-STAT3, c-Myc and Lin28B in parallel. Some of them displayed the dedifferentiation characteristics, such as full of α-fetoprotein granules, increase in size, and nucleocytoplasmic shuttle of Oct4. When these cells were injected into mice, the xenografts mostly displayed the uniform area of hepatic-like tissue with malignant nuclei. The hepatic malignant markers, α-fetoprotein, cytokeratin 7 and cytokeratin 19, were co-expressed in albumin-positive areas, respectively. In conclusion, we established an approach to predict the hepatic premalignance triggered by carcinogen AAI. This premalignant assay system might aid to evaluate the effects of potential carcinogens in liver, and probably to screen the protecting against hepatocarcinogenic efficacy of pharmaceuticals in vitro.

Hepatic Premalignant Alterations Triggered by Human Nephrotoxin Aristolochic Acid I in Canines.

Aristolochic acid I (AAI) existing in plant drugs from Aristolochia species is an environmental human carcinogen associated with urothelial cancer. Although gene association network analysis demonstrated gene expression profile changes in the liver of human TP53 knock-in mice after acute AAI exposure, to date, whether AAI causes hepatic tumorigenesis is still not confirmed. Here, we show that hepatic premalignant alterations appeared in canines after a 10-day AAI oral administration (3 mg/kg/day). We observed c-Myc oncoprotein and oncofetal RNA-binding protein Lin28B overexpressions accompanied by cancer progenitor-like cell formation in the liver by AAI exposure. Meanwhile, we found that forkhead box O1 (FOXO1) was robustly phosphorylated, thereby shuttling into the cytoplasm of hepatocytes. Furthermore, utilizing microarray and qRT-PCR analysis, we confirmed that microRNA expression significantly dysregulated in the liver treated with AAI. Among them, we particularly focused on the members in let-7 miRNAs and miR-23a clusters, the downstream of c-Myc and IL6 receptor (IL6R) signaling pathway linking the premalignant alteration. Strikingly, when IL6 was added in vitro, IL6R/NF-κB signaling activation contributed to the increase of FOXO1 phosphorylation by the let-7b inhibitor. Therefore, it highlights the new insight into the interplay of the network in hepatic tumorigenesis by AAI exposure, and also suggests that anti-premalignant therapy may be crucial for preventing AAI-induced hepatocarcinogenesis.