BACKGROUND: The molecular pathogenesis of @entity8703 of the gastrointestinal tract (GI PDECs) remains unclear. It has been suggested that these lesions either originate from multipotent stem cells that also can serve as the origin of nonendocrine @entity420 or arise due to the @entity8703 (WDECs). METHODS: Ten gastric and 9 colorectal PDECs, 9 gastric WDECs, and 12 @entity14 ( @entity189 ) were analyzed for loss of heterozygosity (LOH) at 11q13 ( @entity16857 ), 17p13.1 ( @entity876 ), 3p14.2 ( @entity21900 ), 3p21.3 ( @entity15893 ), and 18q23 (DCC/ @entity1594 / @entity2536 ), and for immunohistochemical expression of @entity876 , @entity21900 , Rb, and @entity986 . RESULTS: PDECs exhibited high fractional allelic loss (FAL; 0.49), with frequent (> 40%) alterations in @entity876 , Rb, @entity16857 , @entity21900 , and 18q. No significant differences were found between gastric and colorectal PDECs. Gastric WDECs also exhibited high FAL (0.44), with frequent alterations in Rb and/or @entity986 , @entity16857 , and 3p21. @entity189 exhibited a low level of FAL (0.23), with frequent (> 50%) @entity986 and @entity876 alterations. When gastric PDECs and WDECs were compared, substantial similarities were found with respect to FAL (0.42 vs. 0.44) and with respect to individual gene alterations, except in @entity876 , which was consistently altered only in PDECs. @entity189 , which were characterized by a lower FAL (0.56 vs. 0.23) and which lacked alterations in both 3p and Rb, were found to be significantly different from colorectal PDECs. CONCLUSIONS: GI PDECs demonstrated a high level of chromosomal instability; consistent inactivation of both the @entity876 and @entity986 /Rb pathways; and frequent LOH at 3p (possibly involving @entity21900 ), the @entity16857 locus, and 18q. The profile of genetic alterations in PDECs was more consistent with the profile in WDECs than with the profile in @entity189 .

Genetic alterations in XXXX of the gastrointestinal tract.

@entity986 :: ('1029', 'Gene') :: ['p16'] @entity8703 :: ('MESH:D004701', 'Disease') :: ['dedifferentiation of well-differentiated endocrine carcinomas', 'poorly differentiated endocrine carcinomas'] @entity2536 :: ('4087', 'Gene') :: ['Smad2'] @entity189 :: ('MESH:D002277', 'Disease') :: ['CRCs'] @entity876 :: ('7157', 'Gene') :: ['p53'] @entity16857 :: ('4221', 'Gene') :: ['MEN1'] @entity14 :: ('MESH:D015179', 'Disease') :: ['colorectal carcinomas'] @entity15893 :: ('11186', 'Gene') :: ['RASSF1A'] @entity1594 :: ('4089', 'Gene') :: ['DPC4'] @entity420 :: ('MESH:D000230', 'Disease') :: ['adenocarcinomas'] @entity21900 :: ('2272', 'Gene') :: ['FHIT']
@entity8703 :: (MESH:D004701,Disease) :: ['poorly differentiated endocrine carcinomas']
