Purpose: The 8 pancreatic cancer cell lines (BxPC-3, Capan-2, CFPAC-1, HPAC, Capan-1, AsPC-1, MIA PaCa-2, and PANC-1) were investigated to identify the factors which would increase CA19-9 related to the Lewis antigen. CA19-9 in serum is a
well-known tumor marker, and is frequently used for the clinical diagnosis of pancreatic cancer. The oligosaccharide on the CA19-9 epitope is a sialylated Lewis A blood group antigen.
Methods: β3Gal-T was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The phenotypes and genotypes of Lewis antigen were determined by flow cytometry analysis and restriction fragment length polymorphism (RFLP),
respectively. The phenotypes of sLea were assessed by flow cytometry analysis and the sLea on supernatants was detected by sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE). CA19-9 and DUPAN-2 on
supernatants
were measured by enzyme immunoassay.
Results: CA19-9 productions were possible from all cell lines since they all had β3Gal-T and there were no genotypical Lewis negative (le/le). The elevation of CA19-9 was noted on Capan-2 and CFPAC-1, which were phenotypically Lewis
positive
(Le(a+b+)), as expected. Interestingly, it was also elevated in BxPC-3 even though the line was known to be phenotypically Lewis negative (Le(a－b－)). Sialyl Lea appeared to play an important role in this phenomenon. Although CA 19-9
was not
detected in the phenotypically Lewis negative pancreatic cell line without sialyl Lea, the levels of DUPAN-2 were variable.
Conclusion: It was revealed that an elevated CA19-9 was related with increased expression of Lewis gene, not merely the existence of the gene. Further investigations on the role of ST3Gal are warranted to explain the mechanisms of the
variable
levels of DUPAN-2 in Le(a－b－) cell lines.
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