Abstract 390: Direct interaction of Pin1 with HIF-prolyl hydroxylase 2: Implications for breast cancer cell growth and survival

Abstract

Abstract Prolyl hydroxylase domain 2 (PHD2) is the main hypoxia-inducible factor (HIF)-prolyl hydroxylase. PHD2 in normoxia hydroxylates specific proline residues in HIF-1α and HIF-2α, which facilitates their ubiquitination and proteasomal degradation. Although the activity of PHD2 is reduced in hypoxia, significant levels of residual activity of this monooxygenase are still detected under hypoxic conditions. However, its role under hypoxia is poorly understood. Peptidyl-prolyl isomerase (Pin1) binds to target proteins containing phosphorylated serine or threonine residues followed by proline (pS/T-P). As PHD2 harbors several pS/T-P motifs, it may be a potential substrate of Pin1. We found for the first time interaction between Pin1 and PHD2 in human breast cancer MDA-MB-231 cells in normoxic and hypoxic conditions. Additionally, the breast cancer tissue array showed elevated expression of PHD2 as well as Pin1 in tumors compared to adjacent normal tissues. LC-MS/MS spectrometry identified three amino acid residues (S125, T168, and S174) of PHD2 undergoing phosphorylation. Among these, serine 125 was found to be the principal site required for Pin1 binding. As a novel binding partner of Pin1, oncogenic PHD2 can be explored as a therapeutic target for the treatment of breast cancer. Citation Format: Yanymee Nimesia Guillen Quispe, Su-Jung Kim, Soma Saeidi, Gyo-Jin Choi, Chaithanya Chelakkot, Tianchi Zhou, Sang-Beom Bang, Tae-Won Kim, Young-Kee Shin, Young-Joon Surh. Direct interaction of Pin1 with HIF-prolyl hydroxylase 2: Implications for breast cancer cell growth and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 390.