Hakutermit:

carbonic anhydrase IX, expression, mouse, human serum

Background and aims: Carbonic anhydrase IX (CA IX) is a unique member of the CA family. It participates in the regulation of acid-base balance, cell proliferation, adhesion, and malignant processes. This study consisted of two goals: the first was to study the expression of CA IX in mouse tissues, and the second was to develop an immunoassay to detect CA IX levels in human serum.

Methods: mRNA transcription was studied by reverse transcriptase PCR (RT-PCR). CA IX protein was studied by Western blot and immunohistochemistry. The principle behind the immunoassay was to detect CA IX with monoclonal antibodies and chemiluminescent reaction: it was applied to serum samples of controls, and to renal and breast cancer patients.

Results: In mouse tissues, strong expression was observed in the gastric mucosa. Moderate reactions were seen in the colonic enterocytes and pancreatic acini. RT-PCR surprisingly revealed strong signal for CA IX mRNA in the kidney and skeletal muscle, while signal for the protein could not be observed. The exact concentration of CA IX in serum could not be revealed with the immunoassay, although it seemed to detect CA IX protein. Higher values were observed in some serum samples obtained from renal cancer patients compared to the other groups.

Conclusions: The discrepancy between mRNA and protein in the kidney and muscle suggests a tissue-specific post-transcriptional control mechanism for CA IX, possibly related to physiological demands. The immunoassay results confirm that further studies are reasonable to evaluate the value of CA IX as a tumor marker.