1. Academic Validation
  2. Biphasic Effects of Ingenol 3,20-Dibenzoate on the Erythropoietin Receptor: Synergism at Low Doses and Antagonism at High Doses

Biphasic Effects of Ingenol 3,20-Dibenzoate on the Erythropoietin Receptor: Synergism at Low Doses and Antagonism at High Doses

  • Mol Pharmacol. 2015 Aug;88(2):392-400. doi: 10.1124/mol.114.097436.
Jin-Gyo Oh 1 Young-Won Chin 1 Sung-Jo Kim 1 Jong Min Choi 1 Sang Kyum Kim 1 Hee Eun Kang 1 Tae-Hwe Heo 2
Affiliations

Affiliations

  • 1 Laboratory of Pharmacoimmunology, Integrated Research Institute of Pharmaceutical Sciences, College of Pharmacy, Catholic University of Korea, Bucheon, Republic of Korea (J.-G.O., H.E.K., T.-H.H.); College of Pharmacy, Dongguk University-Seoul, Seoul, Republic of Korea (Y.-W.C.); Department of Biotechnology, Hoseo University, Baebang, Asan, Chungnam, Republic of Korea (S.-J.K.); and College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea (J.M.C., S.K.K.).
  • 2 Laboratory of Pharmacoimmunology, Integrated Research Institute of Pharmaceutical Sciences, College of Pharmacy, Catholic University of Korea, Bucheon, Republic of Korea (J.-G.O., H.E.K., T.-H.H.); College of Pharmacy, Dongguk University-Seoul, Seoul, Republic of Korea (Y.-W.C.); Department of Biotechnology, Hoseo University, Baebang, Asan, Chungnam, Republic of Korea (S.-J.K.); and College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea (J.M.C., S.K.K.) thhur92@catholic.ac.kr.
Abstract

Although ingenol 3,20-dibenzoate (IDB) is known as a selective novel protein kinase C (PKC) agonist, its biologic actions and underlying mechanisms remain incompletely understood. In this study, we identified IDB as a proliferative agent for an erythropoietin (EPO)-dependent cell line, UT-7/EPO, through the screening of a natural compound library. To clarify the underlying mechanism of IDB's EPO-like activities, we thoroughly analyzed the mutual relation between EPO and IDB in terms of in vitro and in vivo activities, signaling molecules, and a cellular receptor. IDB substantially induced the proliferation of UT-7/EPO cells, but not as much as EPO. IDB also lessened the anemia induced by 5-fluorouracil in an in vivo mouse model. Interestingly, IDB showed a synergistic effect on EPO at low concentration, but an antagonistic effect at higher concentration. Physical interaction and activation of PKCs by IDB- and EPO-competitive binding of IDB to EPO receptor (EPOR) explain these synergistic and antagonistic activities, respectively. Importantly, we addressed IDB's mechanism of action by demonstrating the direct binding of IDB to PKCs, and by identifying EPOR as a novel molecular target of IDB. Based on these dual targeting properties, IDB holds promise as a new small molecule modulator of EPO-related pathologic conditions.

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