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.