Decrease of human pancreatic cancer cell tumorigenicity by α1,3galactosyltransferase gene transfer

Abstract

The enzyme ␣1,3galactosyltransferase synthesizes the ␣Gal epitope, a carbohydrate structure (Gal␣1,3Gal␤1,4GlcNAc-R), on glycoconjugates in lower mammals. The enzyme is absent in humans but large amounts of natural antibodies that recognize ␣Gal epitopes are present in human serum. It is likely that these antibodies contribute to the host defense and participate in the hyperacute rejection of xenograft. Previous studies indicated that the glycosyltransferase gene transfer into tumoral cells can modify the structure of glycoconjugates at the cell surface and, as a consequence, modulates the metastatic and tumorigenic behaviors of these cells. The aim of our study was to determine whether the expression of ␣Gal epitope can modify the tumorigenicity of human pancreatic cancer cells In the past decades, the incidence of pancreatic cancer has been increasing and it is now the fourth-leading cause of cancer-related deaths in the United States and Western countries. 1,2 This cancer is extremely aggressive and very resistant to current treatments including surgery. 3 Diagnosis in most patients occurs once the tumor has spread over into lymph nodes or formed distant metastases. 4 The molecular mechanism regulating pancreatic tumor cell invasion, metastasis and tumor progression still remains poorly understood. Several studies, however, reported that aberrant glycosylation of glycosphingolipids and glycoproteins expressed in tumor cells has been implicated in metastatic and tumorigenic behaviors of these cells. 5,6 The most common alterations are modifications of ABH, Lewis and blood group-related antigens. Lewis b, Lewis y, H-type and T antigens were expressed in normal pancreas whereas Lewis x, sialyl-Lewis x, sialyl-Lewis a and sialyl-Tn antigens were principally detected in pancreatic cancer tissues. 7-11 Sialyl-Lewis a antigens expressed preferentially at the surface of circulating adenocarcinoma cells are recognized by selectins located on endothelial cell membrane and thus, may play an important role in the metastasis formation consecutive to pancreatic adenocarcinoma. [12][13][14][15] The mechanism by which these antigens arise is not well understood but may involve changes in the activity of glycosyltransferases. In particular, a substantial decrease of ␣1,2fuco-syltransferase activity and an enhanced ␣1,4fucosyltransferase activity have been observed in tumoral pancreatic cell lines compared to normal tissue. 16 This balance can favor the expression of sialyl-Lewis x and sialyl-Lewis a antigens. We have shown recently that the restoration of ␣1,2fucosyltransferase FUT1 expression or the invalidation of ␣1,3/1,4fucosyltransferase FUT3 in human pancreatic tumor cells resulted in the decrease of sialylLewis antigen expression associated with an in vivo decrease in metastatic properties in nude mice. 17,18 These tumor-associated carbohydrate antigens represent potential targets for diagnosis, imaging and new therapeutic treatments such as gene therapy and immune therapy.In this context, the carbohydrate epitope Gal␣...

In vivo targeting of vaccinating tumor cells to antigen-presenting cells by a gene therapy method with adenovirus containing the α1,3galactosyltransferase gene

“…50,[60][61][62][63] Freshly isolated tumor cells that are to be manipulated in a clinical setting to serve as an autologous tumor vaccine expressing a-gal epitopes, are mostly cells that are nondividing in vitro. Expression of these epitopes on nondividing tumor cells may be achieved by transduction with replication defective adenovirus containing the a1,3GT gene.…”

“…A similar selection of a-gal-positive tumor cells, after transfection with a retrovirus containing the a1,3GT gene, also requires the proliferation of the transfected cells for insertion of the gene into the genome of the cell, as previously demonstrated with human cell lines processed to express this epitope. [60][61][62][63] In contrast, transduction with AdaGT results in a-gal epitope expression in a large proportion of the tumor cells (Fig 2). Therefore, in vitro transduction with AdaGT is likely to be suitable for inducing expression of a-gal epitopes on freshly obtained tumor cells that are processed as autologous tumor vaccine.…”

CD55 limits sensitivity to complement-dependent cytolysis triggered by heterologous expression of α-gal xenoantigen in colon tumor cells

“…It has been successfully expressed in a number of human cell lines (14,24,27,53). The ␣-gal epitope increases the sensitivity of tumor cells to human complementdependent cytolysis (CDC) in cell lines of human pancreatic cancer (1), hepatocellular carcinoma (66), and breast cancer (52). In some cases, however, the ␣-gal epitope did not increase the sensitivity of human tumor cells to human complement-mediated lysis (64).…”