Expression of a novel carbonic anhydrase, CA XIII, in normal and neoplastic colorectal mucosa.
BACKGROUND
Carbonic anhydrase (CA) isozymes may have an important role in cancer development. Some isozymes control pH homeostasis in tumors that appears to modulate the behaviour of cancer cells. CA XIII is the newest member of the CA gene family. It is a cytosolic isozyme which is expressed in a number of normal tissues. The present study was designed to investigate CA XIII expression in prospectively collected colorectal tumor samples.


METHODS
Both neoplastic and normal tissue specimens were obtained from the same patients. The analyses were performed using CA XIII-specific antibodies and an immunohistochemical staining method. For comparison, the tissue sections were immunostained for other cytosolic isozymes, CA I and II.


RESULTS
The results indicated that the expression of CA XIII is down-regulated in tumor cells compared to the normal tissue. The lowest signal was detected in carcinoma samples. This pattern of expression was quite parallel for CA I and II.


CONCLUSIONS
The down-regulation of cytosolic CA I, II and XIII in colorectal cancer may result from reduced levels of a common transcription factor or loss of closely linked CA1, CA2 and CA13 alleles on chromosome 8. Their possible role as tumor suppressors should be further evaluated.
Kummola
Laura
L
Institute of Medical Technology, University of Tampere, and Tampere University Hospital, Tampere, Finland. laura.kummola@uta.fi
Hämäläinen
Jonna M
JM
Kivelä
Jyrki
J
Kivelä
Antti J
AJ
Saarnio
Juha
J
Karttunen
Tuomo
T
Parkkila
Seppo
S
D000230:Adenocarcinoma / Q000201:enzymology*; D000236:Adenoma / Q000201:enzymology*; D000483:Alleles; D024401:Carbonic Anhydrase I / Q000096:biosynthesis*; D024402:Carbonic Anhydrase II / Q000096:biosynthesis*; D002256:Carbonic Anhydrases / Q000096:biosynthesis* / Q000235:genetics*; D003106:Colon / Q000201:enzymology*; D015179:Colorectal Neoplasms / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D015536:Down-Regulation; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000201:enzymology*; D020033:Protein Isoforms; D014158:Transcription, Genetic
D020033:Protein Isoforms; D024401:Carbonic Anhydrase I; D024402:Carbonic Anhydrase II; C483903:CA13 protein, human; D002256:Carbonic Anhydrases