Abstract 3296: The receptor-like protein tyrosine phosphatase PTPRH modulates dephosphorylation of the tyrosine kinases EPHA2 and EGFR, alters cell morphology and adhesion, and behaves as a tumor-suppressor in non-small cell lung cancer cell

Abstract Introduction: The delicate balance of protein phosphorylation is often disrupted in cancers, with hyperactivity of kinases and inactivation of phosphatases driving cell proliferation and survival pathways. PTPRH, a protein tyrosine phosphatase, is found to be mutated in ∼5% of non-small cell lung cancer (NSCLC) cases. However, the biological processes in which PTPRH is involved and how they may contribute to tumorigenesis are unknown. Methods: We uncovered PTPRH’s candidate interactors and associated pathways by applying a proximity-dependent biotinylation assay (BioID) and generating a signature transcriptomics in two NSCLC cell lines derived from the primary tumor (NCI-H23) or a metastatic site (NCI-H2023). Spatial subcellular localization, morphological analysis, and cell signaling alteration induced by PTPRH gain or loss were evaluated by confocal microscopy, image analysis, western blot, and cell adhesion assays under basal or stimulated conditions. Functional effects on migration and tumor suppression were assessed using in vitro assays and tail-vein or flank injections of PTPRH-overexpressing NSCLC cells in NOD-SCID mice. Results: PTPRH candidate interactors include signaling molecules and structural proteins linked to integrins and focal adhesions, adherens junctions, migration, and the cytoskeleton, besides stable or transient interactions with the receptor tyrosine kinases (RTK) EGFR, EPHA2, and ROR2, and the phosphatases PTPN3 and PTPRJ. Considering the importance of EGFR in driving lung cancers and the role of EPHA2 in regulating cell adhesion, we delved deeper into understanding how PTPRH regulates RTKs signaling. Overexpression of PTPRH decreased phosphorylation levels of EGFR at the tyrosine residue 1173 (1197) and EPHA2 at tyrosine residue 588 in the primary site-derived cell line following EGF or ephrin-A1/collagen I stimulation. Imaging revealed that the phosphatase and EPHA2 colocalize subcellularly, with PTPRH gain inducing morphological alterations, such as increased eccentricity and smaller size, besides changes in the cytoskeleton organization. These changes are accompanied by increased FAK Y397 phosphorylation, but reduced cell adhesion to the ECM. Additionally, pathway enrichment analysis revealed downregulation of multiple oncogenic, metabolic, and cell adhesion signaling pathways, with increased levels of the phosphatase leading to reduced migration in vitro, suppressed tumor growth, reduced cell colonization to the lungs, prolonged tumor latency, and tumor differentiation in vivo. Conclusion: PTPRH regulates key signaling and structural networks, modulating RTK activity, morphology, adhesion, and tumor behavior. Its loss may facilitate NSCLC progression. Citation Format: Mylena Ortiz, Deeya Patel, Jesus Garcia-Lerena, Andrew C. Nelson, Matthew Swiatnicki, Eran Andrechek. The receptor-like protein tyrosine phosphatase PTPRH modulates dephosphorylation of the tyrosine kinases EPHA2 and EGFR, alters cell morphology and adhesion, and behaves as a tumor-suppressor in non-small cell lung cancer cell [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3296.