Everolimus-inhibited multiple isoforms of UDP-glucuronosyltransferases (UGTs)

Abstract

1. Everolimus is an inhibitor of mammalian target of rapamycin (mTOR) and has been clinically utilized to prevent the rejection of organ transplants. This study aims to determine the inhibition of everolimus on the activity of phase-II drug-metabolizing enzymes UDP-glucuronosyltransferases (UGTs). 2. The results showed that 100 μM of everolimus exerted more than 80% inhibition toward UGT1A1, UGT-1A3 and UGT-2B7. UGT1A3 and UGT2B7 were selected to elucidate the inhibition mechanism, and in silico docking showed that hydrogen bonds and hydrophobic interactions mainly contributed to the strong binding of everolimus toward the activity cavity of UGT1A3 and UGT2B7. Inhibition kinetic-type analysis using Lineweaver-Burk plot showed competitive inhibition toward all these UGT isoforms. The inhibition kinetic parameters (K) were calculated to be 2.3, 0.07 and 4.4 μM for the inhibition of everolimus toward UGT1A1, UGT-1A3 and UGT-2B7, respectively. 3. In vitro-in vivo extrapolation (IVIVE) showed that [I]/K value was calculated to be 0.004, 0.14 and 0.002 for UGT1A1, UGT-1A3 and UGT-2B7, respectively. Therefore, high DDI potential existed between everolimus and clinical drugs mainly undergoing UGT1A3-catalyzed glucuronidation.

Recent progress and challenges in screening and characterization of UGT1A1 inhibitors

“…More recently, everolimus, an inhibitor of the mammalian target of rapamycin (mTOR) that is utilized to prevent rejection of organ transplants, was characterized as a UGT1A1 inhibitor, with a K i value of 2.3 μmol/L 79 . The calculated [ I ]/ K i value in this case was 0.004, indicating that everolimus is unlikely to cause clinically significant DDI via UGT1A1 inhibition in vivo 79 . Diethylstilbestrol, a widely used toxic synthetic estrogen, is a strong competitive inhibitor of UGT1A1-catalyzed estradiol-3- O -glucuronidation in HLM, with a K i value of 2.1 μmol/L 80 , and of the UGT1A1-mediated 4-MU-glucuronidation, also competitively, with a K i value of 3.7 μmol/L 81 .…”

“…Other drugs that display inhibitory effects on UGT1A1 are listed in Table 560., 75., 76., 77., 78., 79., 80., 81., 82., 83.. Tolcapone and entacapone, catechol- O -methyltransferase inhibitors that are used as adjunct in the treatment of Parkinson׳s disease, have similar skeleton, but the use of tolcapone was suspended due to its higher toxicity, and it was replaced by entacapone84., 85..…”

Rapamycin suppresses the PI3K/AKT/mTOR signaling pathway by targeting SIRT1 in esophageal cancer

“…Its anticancer effect was first reported in 2002( 20 ). Rapamycin is an inhibitor of serine/threonine protein kinase mTOR, which is the mechanical target of rapamycin ( 7 ). During the past decade, the majority of studies have focused on the potential anti-aging role of rapamycin in age-related diseases, including cancer and Alzheimer's disease, as well as improving cardiovascular and cerebrovascular cognitive impairment ( 11 , 21 ).…”

“…Rapamycin exhibits antitumor and immunosuppressive properties. As a mTOR-targeting molecule, rapamycin has been approved to prevent the rejection of transplanted organs and to block restenosis after angioplasty ( 7 ). A combination of rapamycin and cisplatin inhibited the growth of various cancer cell lines, such as endometrial ECC-1 cells and cervical carcinoma HeLa cells ( 8 ).…”

In vitro and in vivo methods to assess pharmacokinetic drug– drug interactions in drug discovery and development

“…According to the regulatory guidelines, the inhibition potency, as a perpetrator, needs to be assessed for drug candidates against seven major CYPs, i.e.,1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4/5 (https://www.fda.gov/downloads/drugs/guidances/ucm292362.pdf, https://www.ema.europa.eu/en/documents/scientific‐guideline/guideline‐strategies‐identify‐mitigate‐risks‐first‐human‐early‐clinical‐trials‐investigational_en.pdf, http://www.pmda.go.jp/files/000228122.pdf). Although CYPs are the most important class of drug metabolizing enzymes, there are increasing numbers of DDI cases due to interaction with non‐CYP enzymes and transporters, such as UDP‐glucuronosyltransferases (UGTs), P‐gp, BCRP, OATPs, OATs, and OCTs (Du et al, ; Englund et al, ; Gufford et al, ; Matsunaga, Fukuchi, Imawaka, & Tamai, ; Varma et al, ).…”