Development and validation of nanobodies specific to the oncogenic phosphatase Protein Tyrosine Phosphatase 4A3 (PTP4A3 or PRL-3)

Protein Tyrosine Phosphatase 4A3 (PTP4A3 or PRL-3) is an oncogenic dual specificity phosphatase that drives tumor metastasis, promotes cancer cell survival, has been linked to poor patient prognosis in a variety of tumor types. The mechanisms by which PRL-3 promotes tumor progression are not well understood, which is in part due to lack of tools to study this protein. The development of small molecule inhibitors that are specific to PRL-3 has proven difficult, as the PRL family is >80% homologous. As research tools, antibodies directed against PRL-3 have been more successful, although they are limited to certain assay types. To address this, we have designed, purified, and tested alpaca-derived PRL-3 single domain antibodies, or nanobodies. We have identified 7 unique nanobodies that bind to PRL-3 in ELISA with no activity towards PRL-1 and PRL-2. Anti-PRL-3 nanobodies immunoprecipitated PRL-3 from cell lysates and were used to define PLR-3 localization in human colon cancer cells in immunofluorescence cell staining experiments. These anti-PRL-3 nanobodies represent an important expansion of the tool set used for the study of PRL-3, and can be used to better define the role of PRL-3 in cancer progression while serving as a useful first step in the development of biologics to target PRL-3 in the clinic.