Vitamin E‑Conjugated Phosphopeptide Inhibitor of the Polo-Box Domain of Polo-Like Kinase 1

• Published in: Molecular pharmaceutics 2019-12, Vol.16 (12), p.4867-4877
• Main Authors: Yim, Min Su, Soung, Nak Kyun, Han, Eun Hee, Min, Jin-Young, Han, HoJin, Son, Eun-Ju, Kim, Hak Nam, Kim, BoYeon, Bang, Jeong Kyu, Ryu, Eun kyoung
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Cell Cycle Checkpoints - drug effects; Cell Cycle Proteins - metabolism; Cell Survival - drug effects; Enzyme Activation - drug effects; Flow Cytometry; HeLa Cells; Humans; Mitosis - drug effects; Phosphopeptides - chemistry; Polo-Like Kinase 1; Protein Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins - metabolism; Vitamin E - chemistry
• ISSN: 1543-8384; 1543-8392
• DOI: 10.1021/acs.molpharmaceut.9b00757

Polo-like kinase 1 (Plk1) regulates cell cycle and cell proliferation, and is currently considered a potential biomarker in clinical trials for many cancers. A characteristic feature of Plks is their C-terminal polo-box domain (PBD). Pro-Leu-His-Ser-pThr (PLHS­[pT])the phosphopeptide inhibitor of the PBD of Plk1induces apoptosis in cancer cells. However, because of the low cell membrane-penetration ability of PLHS­[pT], new approaches are required to overcome these drawbacks. We therefore developed a vitamin E (VE) conjugate that is biodegradable by intracellular redox enzymes as an anticancer drug-delivery system. To ensure high efficiency of membrane penetration, we synthesized VE-S–S-PLHS­[pT]­KY (1) by conjugating PLHS­[pT] to VE via a disulfide bond. We found that 1 penetrated cancer cell membranes, blocked cancer cell proliferation, and induced apoptosis in cancer cells through cell cycle arrest in the G2/M phase. We synthesized a radiolabeled peptide (124I-1), and the radioligand was evaluated in in vivo tumor uptake using positron emission tomography. This study shows that combination conjugates are an excellent strategy for specifically targeting Plk PBD. These conjugates have a dual function, with possible uses in anticancer therapy and tumor diagnosis.