Alterations in connexin26 expression during colorectal carcinogenesis.
BACKGROUND
Gap junctional intercellular communication (GJIC) is a mechanism for direct cell-to-cell signalling and is mediated by gap junctions, which consist of transmembrane proteins called connexins (Cxs). Human colorectal epithelial cells express Cx32 and Cx43.


METHODS
Tissue samples (152 from colorectal cancer and 75 from adenoma) were investigated by immunohistochemistry, using the antibody for Cx26. Moreover, Cx26 was assessed in normal epithelium of the colon and rectum, adjacent to colorectal cancer.


RESULTS
In normal epithelium and adenomas, intercellular, punctate staining for Cx26 was observed. In adenomas with severe dysplasia, focally decreased expression of Cx26 was observed. Among 152 colorectal cancers, 55.9% classified only as adenocarcinoma stained positive for Cx26, but mainly cytoplasmic staining was found. We observed a positive correlation between Cx26 expression and tumor G2 grade (p < 0.005). The expression of Cx26 did not correlate with age, sex of patients, tumor localization, lymph node status or tumor size.


CONCLUSIONS
Our results show that during colorectal carcinogenesis, loss of normal intercellular Cx expression occurs. Furthermore, the cytoplasmic presence of Cx26 could indicate a different role of Cx26 in neoplastic cells than participation in GJIC.
Kanczuga-Koda
Luiza
L
Department of Pathology, Medical University of Bialystok, Bialystok, Poland.
Sulkowski
Stanislaw
S
Koda
Mariusz
M
Sulkowska
Mariola
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002450:Cell Communication; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D000072259:Connexin 26; D017630:Connexins / Q000276:immunology / Q000378:metabolism*; D003593:Cytoplasm; D005260:Female; D017629:Gap Junctions; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged
D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26