Cellular prion protein contributes to LS 174T colon cancer cell carcinogenesis by increasing invasiveness and resistance against doxorubicin-induced apoptosis

As the cellular prion protein (PrP(C)) has been implicated in carcinogenesis, we aimed to investigate the effects of cancer cell-specific PrP(C) overexpression from the invasion, metastasis, and apoptosis aspects, by performing cell motility assays, cell proliferation assays under anchorage-dependent and anchorage-independent conditions, and apoptosis evasion when subjected to multiple anti-cancer drugs. Overexpression of PrP(C) in LS 174T was achieved by stable transfection. PrP(C) overexpression was shown to increase cell proliferation in anchorage-dependent and anchorage-independent manners, as shown by more viable cells in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, more colonies formed in soft agar assay and increased resistance to anoikis in poly-2-hydroxyethyl methacrylate-coated surface. PrP(C) overexpression also increased cell motility and invasiveness of LS 174T. Cell adhesion to extracellular matrix using collagen- and fibronectin-coated surfaces revealed increased cell attachment in LS 174T cells overexpressing PrP(C). Analysis of apoptotic and necrotic cells by propidium iodide/annexin V-fluorescein isothiocyanate microscopy and 7-amino-actinomycin D/annexin V-phycoerythrin flow cytometry revealed that PrP(C) overexpression attenuated doxorubicin-induced apoptosis. Human apoptosis antibody array with 35 apoptosis-related proteins revealed that three inhibitor of apoptosis proteins (IAPs)-survivin, X-linked inhibitor of apoptosis protein (XIAP), and cellular inhibitor of apoptosis protein-1 (cIAP-1)-were upregulated in LS 174T cells overexpressing PrP(C) in doxorubicin-induced apoptosis. In conclusion, the overexpression of PrP(C) could enhance the invasiveness and survival of LS 174T colorectal cancer cells, indicating that PrP(C) plays a role in colorectal cancer biology.