Matrigel induces L-plastin expression and promotes L-plastin-dependent invasion in human cholangiocarcinoma cells.

The function of the extracellular matrix (ECM) in the tumor microenvironment is not limited to forming a barrier against tumor invasion. As demonstrated in pathological specimens, cholangiocarcinoma samples exhibit an enrichment of the ECM surrounding the tumor cells. In this study, we examined involvement of the ECM in the regulation of the invasiveness of cholangiocarcinoma cells. The RMCCA1 cholangiocarcinoma cell line was cultured in culture plates either with or without a coating of reconstituted ECM basement membrane preparation (BD Matrigel matrix). In vitro invasion assays were then performed. In addition, the protein expression profile of the cell line was examined using two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry. The proteins expressed and their functional associations with cancer progression were determined. Culturing the RMCCA1 cell line in the BD Matrigel matrix induced cell invasion. Numerous proteins were induced by culturing the RMCCA1 cells in the matrix gel. The expression of L-plastin, an actin-binding protein, was significantly upregulated. The knockdown of L-plastin expression by siRNA silencing significantly suppressed the cellular response to matrix gel-stimulated cancer cell invasion. The ECM promotes the invasiveness of cholangiocarcinoma cells by upregulating L-plastin. These findings suggest the potential exploitation of this mechanism as a means of inhibiting the invasiveness of cholangiocarcinoma cells.

Proteomic profiles of mesenchymal stem cells induced by a liver differentiation protocol.

The replacement of disease hepatocytes and the stimulation of endogenous or exogenous regeneration by human mesenchymal stem cells (MSCs) are promising candidates for liver-directed cell therapy. In this study, we isolated MSCs from adult bone marrow by plastic adhesion and induced differentiation with a liver differentiation protocol. Western blot analyses were used to assess the expression of liver-specific markers. Next, MSC-specific proteins were analyzed with two-dimensional (2D) gel electrophoresis and peptide mass fingerprinting matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-mass spectrometry (MS). To confirm the results from the proteomic study, semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analyses were performed. We demonstrated that MSCs treated with the liver differentiation protocol expressed significantly more albumin, CK19 and CK20, than did undifferentiated cells. In addition the results of proteomic study demonstrated increases expression of FEM1B, PSMC2 and disulfide-isomerase A3 in MSCs treated with the liver differentiation protocol. These results from proteomic profiling will not only provide insight into the global responses of MSCs to hepatocyte differentiation, but will also lead to in-depth studies on the mechanisms of proteomic changes in MSCs.

Comparative proteomic profiles and the potential markers between Burkholderia pseudomallei and Burkholderia thailandensis.

Burkholderia pseudomallei is a bacterial pathogen causing the melioidosis disease, which is predominantly found in tropical areas of Southeast Asia and Northern Australia. Burkholderia thailandensis is a closely related species to B. pseudomallei but it is non-pathogenic species. In this study, we have constructed a proteome reference map of B. pseudomallei at the stationary phase of growth by using two-dimensional gel electrophoresis with a pH 4-7 immobilized pH gradient combined with matrix-assisted laser desorption ionization time of flight mass spectrometry. Approximately 550 spots could be detected by Coomassie brilliant blue G-250 staining, and 88 spots representing 77 unique proteins were identified. Eleven of the gene products were found in multiple spots indicating as isoforms. In attempt to detect distinctive expressed proteins between a virulent and a non-virulent species, the use of comparative proteomic profiles under the same condition were performed. We could identify more than 20 different spots. Twelve out of 14 spots are detected in B. pseudomallei and six proteins have been identified and indicated that they are involved in virulent characters of bacteria. Two hypothetical proteins were expressed and found only in B. pseudomallei. These proteins are potential markers to distinguish between these two species. Our study also provides a useful information of global intracellular protein expression and is a valuable starting point for analyzing a proteomic pathogenicity of the bacterial pathogen.