Evaluation of BAT-26 as an indicator of microsatellite instability in gallbladder carcinomas.

Background/Aims: The genetic pathways of gallbladder cancer are not yet well defined, since the contribution of genetic abnormalities, clarified in other organs, remains questionable. Our aim was to evaluate the role a microsatellite instability in this organ's carcinogenesis. Methodology: We investigated a group of 20 gallbladder carcinomas from Greek patients with regard to alterations in length of the BAT-26 mononucleotide marker as an indicator of microsatellite instability. The findings were correlated with the presence of p53 and ras mutations, alterations of the bax and TGF-βRII genes and tumors' clinicopathological features. Polymerase chain reaction and electrophoretic analysis in a non-denaturating 25% polyacrylamide gel was performed for the detection of BAT-26 size variations. Results: None of our specimens showed microsatellite instability at the BAT-26 marker. Conclusions: BAT-26, an indicator of high-level microsatellite instability, may not be sufficient, when used alone, for determining the microsatellite instability status of gallbladder carcinomas, since these may be characterized by low-level instability. Bax and TGF-βRII genes may not also be targets of instability in this type of tumors.