Carbonic anhydrase is aberrantly and constitutively expressed in both human and murine erythroleukemia cells

The levels of the erythrocyte proteins carbonic anhydrase (CA) and hemoglobin (Hb) change coordinately during human ontogeny. To further probe the coordinate gene expression of these two proteins in vitro, we used an immunoblotting technique to measure their levels during erythroid differentiation in normal human and murine erythroid progenitors, in human and murine erythroleukemia cells, and in normal murine erythroid progenitors infected with Friend virus. Levels of CA and Hb seem to gradually increase in normal differentiating stem cells. In contrast, both human and murine erythroleukemia cells show high levels of CA, but not of Hb, prior to induction of differentiation. Friend virus infection of normal murine progenitors appears to stimulate CA synthesis as an initial and integral step in transformation. In addition, both the erythroleukemia cells and the erythroid progenitors transformed with Friend virus seem to contain much higher levels of CA than Hb during the early stages of differentiation. This relationship is in marked contrast to normal erythroid differentiation, in which Hb levels are always higher than CA levels. Thus, neoplastic transformation seems to be associated with aberrant production of CA that does not correspond to a maturation arrest of the normal differentiation sequence.