Selective up-regulation of claudin-1 and claudin-2 in colorectal cancer.
BACKGROUND
To understand the molecular and morphological alterations in the tight junction in colorectal cancer (CRC) tissues, the expression of eight tight junction proteins in normal and cancer colorectal tissues were compared.


METHODS
Adenocarcinoma tissues and paired normal mucosa were resected from surgical specimens of CRC patients. The expression of occludin, ZO-1, ZO-2, and claudin-1 -5 was analyzed at the mRNA level by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by immunohistochemistry.


RESULTS
The expression of claudin-1 and claudin-2 in cancer tissues was upregulated 40- and 49.2-fold, respectively, at the mRNA level, as compared with that in normal tissues. The up-regulation of these two claudins was also observed at the protein level and it appeared to depend on the depth of tumor invasion.


CONCLUSIONS
Claudin-1 and claudin-2 were found to be overexpressed in CRC tissues. They may be useful as tumor markers and targets for the treatment of colorectal cancer.
Kinugasa
Tetsushi
T
Department of Biochemistry, Faculty of Medicine, Fukuoka University, Fukuoka, Japan. t-kinu@fukuoka-u.ac.jp
Huo
Qun
Q
Higashi
Daijiro
D
Shibaguchi
Hirotomo
H
Kuroki
Motomu
M
Tanaka
Toshihiro
T
Futami
Kitarou
K
Yamashita
Yuichi
Y
Hachimine
Ken
K
Maekawa
Shinichi
S
Nabeshima
Kazuki
K
Iwasaki
Hiroshi
H
Kuroki
Masahide
M
D000230:Adenocarcinoma / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D062445:Claudin-1; D057167:Claudins; D015179:Colorectal Neoplasms / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000378:metabolism*; D015854:Up-Regulation; D062826:Zonula Occludens-1 Protein
D014408:Biomarkers, Tumor; C568108:CLDN1 protein, human; C491875:CLDN2 protein, human; D062445:Claudin-1; D057167:Claudins; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D012333:RNA, Messenger; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein