The significance of carbonic anhydrase expression in human colorectal cancer.
BACKGROUND
Carbonic anhydrase isoenzymes I and II are present in normal colorectal mucosa. This study aimed to determine if carbonic anhydrase is present in colorectal cancer and what is its potential clinical significance.


METHODS
The messenger RNA (mRNA) and protein expression of carbonic anhydrase isoenzyme I were analyzed in fresh specimens of colorectal adenocarcinoma by Northern and Western blots, respectively. The immunohistochemical expression was subsequently studied in a larger number of formalin-fixed surgical specimens.


RESULTS
All of 30 normal colon samples had a strong RNA hybridization signal. Only 4 of 39 paired colorectal cancer and none of 9 normal liver samples had detectable levels of carbonic anhydrase mRNA. Isoenzyme I protein expression showed similar results. In a separate group of patients, immunohistochemical studies showed that 16 of 96 colorectal tumors had positive staining cells. All positive tumors were well or moderately differentiated carcinomas (P < 0.05). When analyzed retrospectively, immunoreactive cases were more likely to be in a group with a good outcome (P < 0.01) and to lack vascular invasion (P < 0.01) than negative cases.


CONCLUSIONS
The majority of colorectal cancers do not express carbonic anhydrase isoenzyme I. The presence of any isoenzyme I-positive immunoreactive cancer cells may be associated with a more favorable outcome in colorectal cancer.
Mori
M
M
Division of Cellular and Molecular Biology, Dana-Farber Cancer Institute, Boston, Massachusetts.
Staniunas
R J
RJ
Barnard
G F
GF
Jessup
J M
JM
Steele
G D
GD
Chen
L B
LB
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015152:Blotting, Northern; D015153:Blotting, Western; D002256:Carbonic Anhydrases / Q000032:analysis* / Q000235:genetics; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000453:epidemiology / Q000473:pathology; D015179:Colorectal Neoplasms / Q000201:enzymology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000201:enzymology / Q000473:pathology; D007527:Isoenzymes / Q000032:analysis* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012189:Retrospective Studies; D014407:Tumor Cells, Cultured
D007527:Isoenzymes; D012333:RNA, Messenger; D002256:Carbonic Anhydrases