Association of downregulated glycotumor-markers and in vivo rejection

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Our original cholangiocarcinoma cell line, TK has a property to secrete some glycosylated tumor markers such as CA19-9, CA50 or sialyl Lewis x (sLe^x) in the culture medium. When IL-2 and/or B7-l gene was transfected into the TK, I observed strong cytopathic effects and in vivo rejections in subcutaneous implantation of the tumor cells in immunocompromised SCID mouse, which did not occur in the wild type cell line.From the precious results of studies, I reasoned that these characteristic changes might originate from aberrant expressions of gylcosylated antigens caused by forced expression of transfected genes. These antigens are glycosylated by glycotransferase, especially by Fuc-T group enzymes. Currently, 5 subtypes, TIII, TIV, TV, TVI, and TVII, has been cloned in human and FucTIII and TVII are proved to be frankly responsible for synthesis of CA19-9 and sLe^x as well as Le^a or Le^b. In this stance, I performed direct comparisons of glycotransferase activity and amounts of gylcosylated antigens in each transfectants. Furthermore, I studied if these cells have mutations in the key elements of glycotransferase gene. When determined by HPLC, although expressions of CA19-9, CA50, and sLex varied in each transfectant these variances were not correlated with enzyme activities. I also confirmed no changes in Fuc-TVII transcription by RT-PCR.In each transfectant, there were no mutations in Fuc-TIII gene specific region by genomic DNA sequences. However, since I reconfirmed significant tumor rejections by implantation study, further studies will be needed to explain the phenomenon.