ALLELOTYPE OF PANCREATIC ADENOCARCINOMA

Knowledge of the patterns of allelic loss has been useful in identifyi ng the spectrum of the tumor suppressor genes involved in various tumo r types. Such analyses in pancreatic carcinoma have been difficult due to the characteristic host desmoplastic reaction to the neoplasm. We have assembled the first allelotype of pancreatic adenocarcinoma, a su rvey for allelic loss among each chromosomal arm, using seven cryostat -dissected neoplasms. The fractional allelic loss in these seven neopl asms was 0.18, a value similar to that seen previously in colorectal c arcinoma. Alleles of chromosome 18q (lost in five of six informative t umors) and of chromosome 17p (lost in four of five informative tumors) were commonly affected. Neither APC mutations (33 neoplasms), allelic shifts of dinucleotide repeats (26 neoplasms), nor immunohistochemica l evidence of retinoblastoma protein underexpression (7 neoplasms) wer e found. Further evaluation of allelic loss in pancreatic cancer would benefit from improved methods for the analysis of lost genetic materi al which overcome the problems posed by the high admixture of nonneopl astic stromal and inflammatory cells in these tumors.