Recognition of the Sodium-Dependent Phosphate Transporter NaPi2b by Monoclonal Antibodies N-NaPi2b in Ovarian Cancer Cells

The sodium-dependent phosphate cotransporter NaPi2b encoded by the SLC34A2 gene is a trans-membrane protein that belongs to the family of phosphate transporters SLC34 and is involved in main-taining phosphate homeostasis in the human body. The phosphate transporter NaPi2b is expressed in several normal tissues and body organs, as well as in malignant neoplasms of the ovary, lung, colorectal, and other types of cancer. The membrane protein NaPi2b is a target for therapeutic humanized antibodies Rebmab200, XMT-1535, and XMT-1536 in cancer cells. These antibodies were created based on MX35 antibodies and are directed against the large extracellular domain of the transporter NaPi2b. Since the location of the N-terminal domain of NaPi2b in the cell has not been experimentally confirmed, this work aimed to analyze the recognition of the phosphate transporter NaPi2b in ovarian cancer cells OVCAR-4 and OVCAR-8 by antibodies against the N-terminal domain of the transporter using Western blot analysis and confocal microscopy.