Factors Related to Increased CA19-9 andLewis Antigen in Pancreatic Cancer Cell Lines

ABSTRACT

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: beta3Gal-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 sLe(a) were assessed by flow cytometry analysis and the sLe(a) 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 beta3Gal-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 Le(a) 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 Le(a), 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.