Gryshkova V. Sodium-dependent phosphate transporter as ovarian cancer marker

The object - identification and characterization of tumor markers. The aim of the work was the identification and characterization of ovarian cancer marker MX35. Applied methods - screening of cDNA-lybrary with antibody, DNA cloning, expression and affinity purification of recombinant proteins, Western-blotting, immunoprecipitation, immunohistochemistry, transient and stable transfection of mammalian cells, hybridoma technique, RT-PCR. Results and novelty - it was firstly revealed that unknown antigen MX35 which is expressed in most of ovarian carcinomas corresponds to sodium-dependent phosphate transporter NaPi2b by screening of OVCAR-3 cDNA library with MX35 antibody. New monoclonal antibodies against large extracellular loop of human NaPi2b were developed. It was shown that these antibodies are able to recognize endogenous NaPi2b protein. The region of tranporter molecule which includes MX35 epitope was discovered. Stable cell line HEK293 that overexpress wild type NaPi2b was created. The high content of NaPi2b was revealed in well-differentiated papillary serous and endometrioid ovarian tumors as well as in normal fallopian tubes and endometrium compare to normal ovary. It was hypothesized that the overexpression of NaPi2b protein in well-differentiated papillary serous and endometriod tumors may be linked to differentiation of ovarian surface epithelium into fallopian tubes epithelium and endometrium, respectively.