ALCAM is a Novel Cytoplasmic Membrane Protein in TNF-α Stimulated Invasive Cholangiocarcinoma Cells

Abstract

<b>Background:</b> Cholangiocarcinoma (CCA), or bile duct cancer, is incurable with a high mortality rate dueto a lack of effective early diagnosis and treatment. Identifying cytoplasmic membrane proteins of invasiveCCA that facilitate cancer progression would contribute toward the development of novel tumor markers andeffective chemotherapy. Materials and <br/><b>Methods</b>: An invasive CCA cell line (KKU-100) was stimulated usingTNF-α and then biotinylated and purified for mass spectrometry analysis. Novel proteins expressed wereselected and their mRNAs expression levels were determined by real-time RT-PCR. In addition, the expressionof ALCAM was selected for further observation by Western blot analysis, immunofluorescent imaging, andantibody neutralization assay. <br/><b>Results</b>: After comparing the proteomics profile of TNF-α induced invasive withnon-treated control cells, over-expression of seven novel proteins was observed in the cytoplasmic membraneof TNF-α stimulated CCA cells. Among these, ALCAM is a novel candidate which showed significant highermRNA- and protein levels. Immunofluorescent assay also supported that ALCAM was expressed on the cellmembrane of the cancer, with increasing intensity associated with TNF-α. <br/><b>Conclusions</b>: This study indicatedthat ALCAM may be a novel protein candidate expressed on cytoplasmic membranes of invasive CCA cells thatcould be used as a biomarker for development of diagnosis, prognosis, and drug or antibody-based targetedtherapies in the future.