Effect of Anti-NaPi2b Monoclonal Antibody on Phosphate Transport in Renal Cancer Cell Line SK-RC-18

The sodium-dependent phosphate transporter NaPi2b (SLC34A2, NaPi-IIb, NPT2b) is involved in regulation of inorganic phosphate metabolism. Its expression was detected in a set of normal and malignant tissues predominantly on mRNA level. Here we describe NaPi2b protein expression in tubules of human kidney by using immunohistochemical analysis with anti-NaPi2b mAb. Patch-clamp technique was used to study effect of anti-NaPi2b mAb on sodium-dependent phosphate current in renal cancer cells (SK-RC-18 cell line) expressing high level of NaPi2b protein. We demonstrate that incubation of SK-RC-18 cells with anti-NaPi2b mAb decreases phosphate current in 70% cells while unspecific antibody A33 does not produce any effect. Thus, anti-NaPi2b mAb can serves as a potential specific inhibitor of NaPi2b mediated phosphate transport. NaPi2b and anti-NaPi2b mAb have a great potential for diagnosis and treatment of different pathologies related to aberrant expression and function of NaPi2b phosphate transporter.