Carbonic anhydrase IX (CA IX)expression in renal cell carcinoma and transitional cell carcinoma of urinary tract
Abstract
Aim: The aim of our study was to investigate the presence of soluble CA IX protein (s-CA IX) in tumor culture media in vitro and body fluids of patients carrying CA IX protein positive tumors. The final purpose was to improve present diagnostic methods to s-CA IX detection and to determine its possible use as a marker of renal clear cell carcinoma (RCC) and transitional cell carcinoma (TCC).
Material and methods: In the preliminary study were two groups of patients: 1. RCC patients, 2.
TCC patients. In the first group were included 31 RCC patients and 61 controles, in the second group 32 patients with endoscopic suspicion for TCC and 16 controles.
We used immunohistochemical staining employing MAb M75 for CA IX identification in tumor tissue. In tumor extracts and body fluids we used Western blotting and ELIS A for quantitation of the s-CA IX protein.
Results: In the RCC group s-CA IX protein was detected only in patients with proven RCC. In the blood 13 (41,9%) from 31 were positive.
In urine 19 (70%) from 27 were CA IX protein positive. Control specimens were all s-CA IX negative.
In the TCC group the tumor was identified in 23 patients histologically Positive s-CA IX was in 16 (69,6%) of them. Negative finding of s-CA IX was in 7 (30,4%) patients.
Serum from all TCC patients was s-CA IX negative, even the serum from patients with CA IX positive urine. Conclusion: We demonstrated shedding of CA IX into body fluids in patients with RCC and TCC, although in exremely low concentrations.
Nevertheless, Western blotting combined with enhanced chemiluminiscence is specific and extremely sensitive method allowing s-CA IX detection in body fluids. Our present data suggest that suitable quantitave method for s-CA IX detection should be developed, which in turn will enable evaluation of clinical significance of CA IX expression in RCC and TCC patients.