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  • MEMBRANE  (2)
  • 1
    Keywords: CELLS ; EXPRESSION ; tumor ; BLOOD ; carcinoma ; human ; MICROSCOPY ; liver ; PROTEIN ; PROTEINS ; TUMORS ; FAMILY ; RAT ; hepatocytes ; MEMBER ; MEMBERS ; antibodies ; MOUSE ; IDENTIFICATION ; RAT-LIVER ; MEMBRANE ; metastases ; CONJUGATE ; LOCALIZATION ; EPITHELIAL-CELLS ; HEPATOCYTE CANALICULAR ISOFORM ; METASTATIC CARCINOMAS ; MULTIDRUG-RESISTANCE PROTEIN ; POLYPEPTIDE OATP2
    Abstract: Transport proteins mediating the selective uptake of organic anions into human hepatocytes include the organic anion transporters SLC21A6 (also termed OATP2, OATP-C, or LST-1) and SLC21A8 (OATP8). Both transporters are localized to the basolateral membrane of human hepatocytes. Because of the importance of these transporters for hepatobiliary elimination, including the removal of bilirubin and its conjugates from the blood circulation, we have generated monoclonal antibodies for studies on the expression and localization of these transport proteins. We describe two antibodies, designated monoclonal antibody MDQ (mMDQ) and monoclonal antibody ESL (mESL), directed against the amino terminus and the carboxyl terminus of human SLC21A6, respectively. Both antibodies have been characterized by immunoblot analysis, immunoprecipitation, and immunofluorescence microscopy. While mESL reacted specifically with SLC21A6, mMDQ detects both SLC21A6 and SLC21A8. Neither of the two antibodies reacted with other human, or with dog, rat, or mouse liver SLC21A family members. Antibody mMDQ may be used for the simultaneous detection of SLC21A6 and SLC21A8 in immunoblotting because of its immunoreactivity with both molecules and because of the different molecular masses of both glycosylated proteins in human hepatocytes. This is exemplified in hepatocellular carcinomas where SLC21A6 and SLC21A8 were differentially synthesized and showed an irregular staining pattern. Both transport proteins have not been detected in human hepatoma HepG2 cells. In routine paraffin sections, 10 of 12 hepatocellular carcinomas were focally positive with antibody mMDQ. In contrast, cholangiocarcinomas and liver metastases of colorectal and pancreatic adenocarcinoma were negative without exception. This suggests the usefulness of SLC21A6/SLC21A8 within a panel of tumor markers for hepatocellular carcinomas. Moreover, both antibodies should be useful in studies on the expression and localization of two important uptake transporters of human hepatocytes under physiologic and pathophysiologic conditions
    Type of Publication: Journal article published
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  • 2
    Keywords: CELLS ; EXPRESSION ; GROWTH ; GROWTH-FACTOR ; IN-VITRO ; proliferation ; Germany ; MODEL ; THERAPY ; VITRO ; GENE ; PROTEIN ; TISSUE ; ACTIVATION ; MECHANISM ; MARKER ; ANTIGEN ; mechanisms ; ALPHA ; MEMBRANE ; LINE ; MARKERS ; EXTRACELLULAR-MATRIX ; BETA ; EPITHELIAL-CELLS ; PHENOTYPE ; vimentin ; adenocarcinoma ; GROWTH-FACTOR-BETA ; chronic pancreatitis ; LONG-TERM CULTURE ; FACTOR-BETA ; molecular ; MATRIX ; fibrosis ; pancreas ; RE ; immortalization ; basement membrane ; BASEMENT-MEMBRANE ; collagen ; HUMAN-FIBROBLASTS ; TRANSFECTION ; TGF-BETA ; VITAMIN-A ; DESMIN ; ACIDIC PROTEIN ; MOLECULAR-MECHANISMS ; DUCT CELLS ; TGF beta ; ABILITY ; PLUS ; CYCLE ARREST ; HEPATIC-FIBROSIS ; LIVER FIBROSIS ; pancreatic stellate cells ; TRANSFORMING GROWTH-FACTOR-BETA-1
    Abstract: Tissue fibrosis is one of the characteristics of chronic pancreatitis and pancreatic adenocarcinoma. Activated pancreatic stellate cells (PSC) play a central role in this process. However, analysis of the molecular mechanisms leading to PSC activation is hampered by the lack of an established human PSC line. To overcome this problem, we immortalized and characterized primary human PSC. The cells were isolated by the outgrowth method and were immortalized by transfection with SV40 large T antigen and human telomerase ( hTERT). Primary human PSC served as controls. An immortalized line, RLT-PSC, was analyzed for the expression of stellate cell markers. Moreover, the effects of transforming growth factor beta 1(TGF beta 1) or platelet-derived growth factor stimulation and of cultivation on basement membrane components or N-acetylcysteine (NAC) treatment on gene and protein expression and proliferation were analyzed. Immortal RLT-PSC cells retained the phenotype of activated PSC proven by the expression of alpha-smooth muscle actin (alpha SMA), vimentin, desmin and glial fibrillary acidic protein (GFAP). TGF beta 1 treatment upregulated the expression of alpha SMA, collagen type I (Col I), fibronectin and TGF beta 1. Incubation of RLT-PSC cells and primary human activated PSC on Matrigel plus NAC treatment resulted in a deactivated phenotype as evidenced by a decrease of aSMA, connective tissue growth factor and Col I expression and by a decreased proliferation of the cells. Moreover, this treatment restored the ability of the cells to store vitamin A in cytoplasmic vesicles. In conclusion, we have established an immortal pancreatic stellate cell line, without changing the characteristic phenotype. Importantly, we were able to demonstrate that besides soluble factors, the matrix surrounding PSC plays a pivotal role in the maintenance of the activation process of PSC. Cultivation of activated PSC on a reconstituted basement membrane plus treatment with NAC was able to deactivate the cells, thus pointing to the possibility of an antifibrosis therapy in chronic pancreatitis
    Type of Publication: Journal article published
    PubMed ID: 16127427
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