OBJECTIVETo investigate 18q21 LOH in human pancreatic ductal adenocarcinomas and chronic pancreatitis by fluorescence in-situ hybrydization (FISH) technique, and to analyze the relationship between 18q21 LOH and clinicopathologic characteristics.

METHODSRP11-729G3 and RP11-850A17, the regions on 18q21, were selected as the target fragments, the region RP11-621L6, close to the centromere of chromosome 18, was selected as the reference fragment. The specific BAC clones were used to isolate and purify the corresponding genomic DNA, which were labeled with biotin or DIG by nick translation into dual color probes. 18q21 LOH was assessed by dual-color FISH in 30 cases of pancreatic ductal adenocarcinoma and 10 cases of chronic pancreatitis. All samples were 10% formalin fixed and paraffin embedded. The relationship between 18q21 LOH and clinicopathologic characteristics was analyzed.

RESULTSAmong 30 cases of pancreatic ductal adenocarcinoma, 25 cases showed LOH at the region RP11-729G3 (83.3%), and 26 cases showed LOH at the region RP11-850A17 (86.6%). Among these, 25 cases with LOH at both regions, 1 case showed LOH only at the region of RP11-850A17. No LOH was found in 10 cases of chronic pancreatitis.

CONCLUSIONS18q21 LOH is a high-frequency event in human pancreatic ductal adenocarcinomas. LOH at the regions RP11-729G3 and RP11-850A17 demonstrates a high concordance. 18q21 may play an important role during pancreatic carcinogenesis and tumor progression. 18q21 LOH may be used as a diagnostic marker for pancreatic ductal adenocarcinoma.