In MT110 containing co-cultures, 50% of the initial GLuc activity was observed. of high risk HB. strong class=”kwd-title” Keywords: EpCAM (CD326), PBMC, hepatoblastoma, immunotherapy, therapeutic antibodies, T cells Introduction Hepatoblastoma (HB) is the most common solid liver tumors in children and account for approximately 1.5% of all pediatric malignancies.1-3 A complete resection of the tumor represents the only curative chance for young patients. However, 60% of the HB are not resectable due to their advanced stage at diagnosis, and chemotherapy based on the DNA-damaging agent cisplatin (CDDP) is needed.4 Despite aggressive SB-674042 chemotherapeutic treatment post-surgery, recurrence is frequent among high-risk HB patients.5 Experimental approaches such as targeted therapy based on the multikinase inhibitor sorafenib are being tested to ameliorate disease outcome.6 Furthermore, combined transplantation of liver and peripheral blood stem cells may be a valid therapeutic option for recurrent HB.7 Pathological HB appears as an embryonal malignancy manifesting epithelial differentiation with mesenchymal components. HB cells secrete the -fetoprotein (AFP) and are present on their surface a high density of cell adhesion molecules like glypican 3 and CD326 (best known as epithelial cell adhesion molecule, EpCAM). Using immunohistochemistry and immunoelectron microscopy, the expression of EpCAM was observed in 70C80% of HB cases, in up to 100% of cells in epithelial tumor areas.8,9 EpCAM is expressed on a variety of human tissues and is overexpressed by some neoplasms including hepatic tumor, breast cancer, ovarian cancer and gallbladder carcinoma.10-13 EpCAM is involved in cell adhesion, intracellular signaling, migration, proliferation and differentiation.14 The overexpression of SB-674042 CD326 in hepatic malignancies is associated with a poor survival rate13 as CD326 promotes tumor progression by activating the expression of proto-oncogene em c-MYC /em .15 EpCAM is a well-known target for therapeutic antibodies against epithelial tumors.16 Antibodies achieve their therapeutic effect by blocking EpCAM-mediated signal transduction and or by promoting antibody-dependent cell cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).17 The immune cells underlying these effects include natural killer (NK) cells as well as subpopulations of T cells. T cells are part of the innate immune system and represent a minor subset (1C10%) of peripheral T cells.18 Up to 90% T cells of the peripheral blood bear a T cell receptor (TCR) that SB-674042 is composed of V9 and V2 chains.19 These unconventional T cells lack classical restriction on major histocompatibility complex (MHC)20 and are activated via their TCR or NKG2D molecules.21,22 T cells are known for their capacity of lysing various tumor cells in vitro.23,24 The present study aimed at analyzing the value of EpCAM as a target for the immunotherapy of HB. An immunotherapeutic approach involving antibodies and T cells was investigated in HB cells previously exposed to CDDP. Results EpCAM expression by HB cells in vitro and in vivo To assess whether immunotherapy could be a Emr4 promising tool for treating HB we screened for tumor infiltrating lymphocytes (TILs) in vivo. CD45 is usually a tyrosine-protein phosphatase expressed on leukocytes and is overexpressed in up to 50% of HB cases, as revealed by a gene expression analysis (, data not shown). Slices from tumors explanted from a patient with epithelial HB were stained for the detection of CD45, revealing immune cells infiltrating the tumor parenchyma (Fig.?1). These leukocytes may play a prominent role during immunotherapy. Open in a separate window Physique?1. Staining for tumor-infiltrating leukocytes. Slices of a hepatoblastoma tissue sample revealed infiltrating CD45+ cells by DAB-based immunohistochemistry. Shown are two regions of the same tissue. Since CD326 is usually highly expressed by HB, it represents a possible target for immunotherapeutic applications.8,25 As demonstrated by flow cytometry, HUH6 and HepT1.