An immunochemical and immunohistochemical study of aldolase isozymes in renal cell carcinoma

To assess changes in aldolase isozyme patterns (A, B, and C) in renal cell carcinoma (RCC) tissues and to evaluate whether serum aldolase A might be a useful marker for RCC, quantitative analysis by enzyme immunoassay and immunohistochemical localization were performed. Concentrations of aldolase A in RCC (7300 +/- 6300 ng./mg. protein n = 26) were significantly higher than those of normal cortex (720 +/- 410 ng./mg. protein, n = 14, p less than 0.01); concentrations of aldolase C in RCC (48.0 +/- 8.0 ng./mg. protein) were also significantly higher than those of normal cortex (8.7 +/- 4.7 ng./mg. protein, p less than 0.01). On the other hand, concentrations of aldolase B in normal cortex were 18,100 +/- 10,100 ng./mg. protein (n = 14), whereas the values in RCC were only 130 +/- 270 ng./mg. protein, a significant lowering (p less than 0.01). Immunohistochemically, aldolases A and C were found localized in all RCC tissues (n = 10); aldolase B was faintly stained in only a few tumor cells of two cases (20%). Levels of serum aldolase A were elevated (greater than 300 ng./ml.) in 30 (75%) of 40 patients with RCC as compared to three (6.3%) of 48 individuals with urogenital benign diseases and in seven (21%) of 34 cases with non-RCC urogenital malignancies. Since it is generally accepted that RCC are derived from renal proximal tubules, these findings indicate that aldolase B, the predominant isozyme in the normal case, changes into aldolases A and C during carcinogenesis and that serum aldolase A could be a new useful biomarker for RCC.