Alterations of transforming growth factor-beta 1 receptor type II occur in ulcerative colitis-associated carcinomas, sporadic colorectal neoplasms, and esophageal carcinomas, but not in gastric neoplasms.
OBJECTIVE
Gastric cancers, sporadic colorectal cancers, and ulcerative colitis (UC)-associated colorectal carcinomas and dysplasias manifest microsatellite instability (MI); however, esophageal carcinomas rarely exhibit MI. Recently, a transforming growth factor-beta 1 type II receptor (TGF-beta 1RII) mutation in a coding microsatellite was described in primary colorectal carcinomas demonstrating MI. No previous studies of TGF-beta 1RII have addressed mechanisms of inactivation other than MI in human tumors; furthermore, MI-negative tumors have not been examined for TGF-beta 1RII mutation. We evaluated 138 primary human neoplasms for mutation in the poly-A microsatellite tract of TGF-beta 1RII. Additionally, a group of esophageal tumors was evaluated for the expression of TGF-beta 1RII messenger RNA (mRNA).


METHODS
First, we determined whether MI was present at other chromosomal loci in these lesions. The poly-deoxyadenine (poly-A) microsatellite tract within the TGF-beta 1RII coding region was then PCR-amplified. In a group of MI-negative esophageal tumors, RT-PCR was performed to determine the expression of TGF-beta 1RII mRNA.


RESULTS
Among 17 MI+ UC specimens, 3 (18%) demonstrated TGF-beta 1RII poly-A tract mutation (2 cancers and 1 dysplasia), while 2 (4%) of 44 MI-negative UC specimens (1 dysplasia and 1 tumor), and 13 (81%) of 16 MI+ sporadic colorectal cancers, contained TGF-beta 1RII poly-A mutation. No gastric or esophageal tumors contained TGF-beta 1RII mutation. Among 21 MI-negative esophageal carcinomas. 6 cases (28.5%) had TGF-beta 1RII transcripts that were low or undetectable by RT-PCR.


CONCLUSIONS
Mutation within the poly-A microsatellite tract of TGF-beta 1RII occurs early in a subset of UC-neoplasms and commonly in sporadic colorectal cancers, but may be rare in MI+ gastric tumors. Diminished expression of TGF-beta 1RII mRNA in esophageal tumors suggests that mechanisms of inactivation in this gene other than MI play a role in esophageal carcinogenesis.
Souza
R F
RF
Department of Medicine (GI Division), University of Maryland School of Medicine, USA.
Garrigue-Antar
L
L
Lei
J
J
Yin
J
J
Appel
R
R
Vellucci
V F
VF
Zou
T T
TT
Zhou
X
X
Wang
S
S
Rhyu
M G
MG
Cymes
K
K
Chan
O
O
Park
W S
WS
Krasna
M J
MJ
Greenwald
B D
BD
Cottrell
J
J
Abraham
J M
JM
Simms
L
L
Leggett
B
B
Young
J
J
Harpaz
N
N
Reiss
M
M
Meltzer
S J
SJ
D003093:Colitis, Ulcerative / Q000150:complications*; D015179:Colorectal Neoplasms / Q000209:etiology / Q000235:genetics*; D004938:Esophageal Neoplasms / Q000235:genetics*; D006801:Humans; D018895:Microsatellite Repeats; D009154:Mutation; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000032:analysis; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics*; D016212:Transforming Growth Factor beta / Q000235:genetics*
D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II