Fate of extrahepatic human stem and precursor cells after transplantation into mouse livers.

In recent years, a large number of groups studied the fate of human stem cells in livers of immunodeficient animals. However, the interpretation of the results is quite controversial. We transplanted 4 different types of human extrahepatic precursor cells (derived from cord blood, monocytes, bone marrow, and pancreas) into livers of nonobese diabetic/severe combined immunodeficiency mice. Human hepatocytes were used as positive controls. Tracking of the transplanted human cells could be achieved by in situ hybridization with alu probes. Cells with alu-positive nuclei stained positive for human albumin and glycogen. Both markers were negative before transplantation. However, cells with alu-p…

CYP2D6 increases toxicity of the designer drug 4-methylthioamphetamine (4-MTA)

4-Methylthioamphetamine (4-MTA) belongs to a group of new amphetamine derivatives that is usually sold as "ecstasy" or "flatliners" on the illicit drug market. Large interindividual differences in 4-MTA mediated toxicity have been reported in humans. Therefore, we tested whether CYP2D6 or its variant alleles as well as CYP3A4 influence the susceptibility to 4-MTA. For this purpose, we used the colony formation assay with Chinese hamster lung fibroblast V79 cells expressing human wild-type CYP2D6 (CYP2D6*1), the low activity alleles CYP2D6*2, CYP2D6*9, as well as human CYP3A4. The obtained results showed that the expression of wild type CYP2D6*1 clearly enhanced the susceptibility to the cyt…

ErbB-3 predicts survival in ovarian cancer.

Background HER3 (erbB-3) is a member of the epidermal growth factor receptor (EGFR) family. After dimerization with other members of the EGFR family several signal transduction cascades can be activated, including phosphoinosite 3′-kinase (PI3-K)/Akt and extracellular signal-regulated kinase (ERK1/2). Here, we studied a possible association between HER3 expression and prognosis in patients with ovarian cancer. Methods Tumor tissue of 116 consecutive patients diagnosed with primary epithelial ovarian cancer between 1986 and 1995 was analyzed immunohistochemically for HER3 expression. A possible influence of HER3 expression on survival was studied by multivariate Cox regression adjusting for …

In Vitro Cultured Islet‐Derived Progenitor Cells of Human Origin Express Human Albumin in Severe Combined Immunodeficiency Mouse Liver In Vivo

Studies in rodents suggest the presence of a hepatopancreatic stem cell in adult pancreas that may give rise to liver cells in vivo. The aim of the present study was to determine the ability of human islet-derived cells to adopt a hepatic phenotype in vivo. Cultured human islet-derived progenitor cells that did not express albumin in vitro were stained with the red fluorescent dye PKH26 and injected into the liver of severe combined immunodeficiency mice. After 3 or 12 weeks, red fluorescent cells were detected in 11 of 15 livers and were mostly single cells that were well integrated into the liver tissue. Human albumin was found in 8 of 11 animals by immunohistochemistry, and human albumin…

Trastuzumab therapy vs tetracycline controlled ERBB2 downregulation: influence on tumour development in an ERBB2-dependent mouse tumour model

Trastuzumab (Herceptin) has improved therapy of breast cancer. Only patients overexpressing ERBB2 are treated with trastuzumab, whereas its use in tumours without ERBB2 expression is useless. This led to the concept that the subgroup of trastuzumab-sensitive tumours is ‘ERBB2-dependent', meaning that ERBB2 signalling is indispensable for growth of these tumours. We used a mouse model that allows anhydrotetracycline (ATc)-controlled downregulation of ERBB2 in tumour tissue. ERBB2 mRNA and protein expression were downregulated below detection limit leading to a macroscopically complete tumour remission within 14 days. Tumour remission was accompanied by a strong decrease in proliferation, a m…

Role of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) for prognosis in endometrial cancer

Abstract Background. Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) contribute to the invasiveness of many carcinomas. Here, we studied a possible association between cytosolic uPA and PA-1 concentrations in tumor tissue with prognosis in patients with endometrial cancer. Methods. Cytosolic concentrations of uPA and PAI-1 were determined in 69 primary endothelial adenocarcinomas using an enzyme-linked immunoassay (ELISA). A possible influence of uPA and PAI-1 was studied by multivariate Cox regression adjusting for the established clinical prognostic factors FIGO-stage, grading, depth of invasion, diabetes mellitus and age. Results. Both uPA ( …

ERBB2 Induces an Antiapoptotic Expression Pattern of Bcl-2 Family Members in Node-Negative Breast Cancer

AbstractPurpose: Members of the Bcl-2 family act as master regulators of mitochondrial homeostasis and apoptosis. We analyzed whether ERBB2 influences the prognosis of breast cancer by influencing the proapoptotic versus antiapoptotic balance of Bcl-2 family members.Experimental Design: ERBB2-regulated Bcl-2 family members were identified by inducible expression of ERBB2 in MCF-7 breast cancer cells and by correlation analysis with ERBB2 expression in breast carcinomas. The prognostic relevance of ERBB2-regulated and all additional Bcl-2 family members was determined in 782 patients with untreated node-negative breast cancer. The biological relevance of ERBB2-induced inhibition of apoptosis…

Influence of CYP2D6 polymorphism on the cytotoxicity of the designer drug 4-methylthioamphetamine (4-MTA)

Hepatocytes cultured in alginate microspheres: an optimized technique to study enzyme induction.

An important application of hepatocyte cultures is identification of drugs acting as inducers of biotransformation enzymes that alter metabolic clearance of other therapeutic agents. In the present study we optimized an in vitro system with hepatocytes cultured in alginate microspheres that allow studies of enzyme induction with excellent sensitivity. Induction factors obtained with standard inducers, such as 3-methylcholanthrene or phenobarbital, were higher compared to those with conventional hepatocyte co-cultures on collagen coated dishes. This is illustrated by activities of 7-ethoxyresorufin-O-deethylase (EROD) after incubation with 5 microM 3-methylcholanthrene (3-MC), a standard ind…

4-Epidoxycycline: an alternative to doxycycline to control gene expression in conditional mouse models

Since the pioneering work by Gossen and Bujard in 1992 demonstrating the usefulness of the Escherichia coli derived tet resistance operon for regulating gene expression a large collection of doxycycline-controlled transgenic mice has been established. Gene switching in eukaryotic tissue culture cells or mice requires administration of tetracycline, anhydrotetracycline or doxycycline to efficiently inactivate the transactivator protein tTA (TET-OFF system) or alternatively to activate the reverse transactivator protein rtTA (TET-ON system). However, the antibiotic activity of doxycycline can create an imbalance of the intestinal flora, resulting in diarrhoea and in a smaller number of animal…

Generation of human hepatocytes by stem cell technology: definition of the hepatocyte

Since 1999, numerous articles have reported the generation of hepatocytes from different types of extrahepatic stem or precursor cells. This opens exciting new possibilities for pharmacology and toxicology, as well as for cell therapy. Hepatocyte marker expression, including albumin, cytokeratin 18, c-met, alpha-fetoprotein and cytochrome P450 3A4 and -2B6, has been observed after transplantation of different types of human stem cells into the liver of laboratory animals or in vitro after incubation with cytokines. These intriguing observations have prompted scientists to classify stem cell-derived cell populations as hepatocytes. However, this conclusion may be premature. It has been shown…

Role of the progesterone receptor for paclitaxel resistance in primary breast cancer

Paclitaxel plays an important role in the treatment of primary breast cancer. However, a substantial proportion of patients treated with paclitaxel does not appear to derive any benefit from this therapy. We performed a prospective study using tumour cells isolated from 50 primary breast carcinomas. Sensitivity of primary tumour cells to paclitaxel was determined in a clinically relevant range of concentrations (0.85-27.2 microg ml(-1) paclitaxel) using an ATP assay. Chemosensitivity data were used to study a possible association with immunohistochemically determined oestrogen and progesterone receptor (ER and PR) status, as well as histopathological parameters. Progesterone receptor (PR) m…

Dephosphorylation of p-ERK1/2 in relation to tumor remission after HER-2 and Raf1 blocking therapy in a conditional mouse tumor model

Several studies have shown that HER-2/neu (erbB-2) blocking therapy strategies can cause tumor remission. However, the responsible molecular mechanisms are not yet known. Both ERK1/2 and Akt/PKB are critical for HER-2-mediated signal transduction. Therefore, we used a mouse tumor model that allows downregulation of HER-2 in tumor tissue by administration of anhydrotetracycline (ATc). Switching-off HER-2 caused a rapid tumor remission by more than 95% within 7 d of ATc administration compared to the volume before switching-off HER-2. Interestingly, HER-2 downregulation caused a dephosphorylation of p-ERK1/2 by more than 80% already before tumor remission occurred. Levels of total ERK protein…