Overexpression of claudin proteins in esophageal adenocarcinoma and its precursor lesions.
Claudins are components of tight junctions important in intercellular barriers and cell polarity. The authors identified upregulation of Claudins 3, 4, and 7 in gastric adenocarcinoma using Affymetrix U-133 oligonucleotide microarrays and immunohistochemistry (IHC). While normal gastric mucosa lacked Claudin 3, 4, and 7 expression, intestinal metaplasia and dysplasia showed these proteins. The authors hypothesized that Claudins would be similarly overexpressed in Barrett's esophagus (BE)/adenocarcinoma. Claudins 3, 4, and 7 gene expression was analyzed by Affymetrix U-133 microarrays in three esophageal adenocarcinomas, one case of BE, and three normal esophagi. IHC validation was performed using tissue microarrays constructed from esophageal resection specimens containing squamous (44 cases), gastric (40 cases), and non-dysplastic BE (16 cases), low-grade and high-grade dysplasia (16 and 26 cases), adenocarcinoma (58 cases), and nodal metastases (27 cases). IHC staining was scored semiquantitatively (0+ to 4+). By microarray analysis, Claudin 3 showed a marked increase in mRNA expression compared with normal esophagus (approximately 100-fold). Claudins 4 and 7 were modestly increased (2.2- and 1.3-fold). By IHC, Claudin 3 expression was 1+ in most (>95%) normal squamous or gastric tissues and 2+ to 4+ in more than 80% of high-grade dysplasia, adenocarcinoma, and metastases specimens. Claudin 4 protein expression was 2+ or less in most squamous and gastric mucosa (>90%) but 3+ or 4+ in BE, low- and high-grade dysplasia, adenocarcinoma, and metastases specimens (>90%). Claudin 7 expression was minimal in squamous and gastric mucosa but strong (3+ to 4+) in BE and low-grade dysplasia. In high-grade dysplasia, adenocarcinoma, and metastases, Claudin 7 was less intense, with 60% to 70% staining 3+ or 4+ and 30% to 40% staining weakly (1+ or 2+). The findings suggest that alterations in Claudin proteins are an early event in tumorigenesis and may provide targets for diagnosis and directed therapy for esophageal adenocarcinoma and its precursors.
Johns Hopkins University School of Medicine, Baltimore, Maryland 21230,USA. emontgom@jhmi.edu
Elizabeth
E
Montgomery
Adam J
AJ
Mamelak
Michael
M
Gibson
Anirban
A
Maitra
Salwa
S
Sheikh
Samir S
SS
Amr
Stephen
S
Yang
Malcolm
M
Brock
Arlene
A
Forastiere
Shengle
S
Zhang
Kathleen M
KM
Murphy
Karin D
KD
Berg
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001471:Barrett Esophagus / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D062465:Claudin-3; D062506:Claudin-4; D057167:Claudins; D004938:Esophageal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D011230:Precancerous Conditions / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D015854:Up-Regulation
D014408:Biomarkers, Tumor; C568122:CLDN3 protein, human; C568157:CLDN4 protein, human; C473255:CLDN7 protein, human; D062465:Claudin-3; D062506:Claudin-4; D057167:Claudins; D008565:Membrane Proteins; D012333:RNA, Messenger