Herein, we pursue the hypothesis that the structure of nordihydroguaiaretic acid (NDGA) can be refined for selective potency against the insulin-like growth factor 1 receptor (IGF-1R) as a potential therapeutic target for breast cancer while diminishing its action against other cellular targets. Thus, a set of NDGA analogs (7a-7h) was prepared and examined for inhibitory potency against IGF-1R kinase and an alternative target, 15-lipoxygenase (15 LOX). The anti-cancer effects of these compounds were determined by their ability to inhibit IGF-1 mediated cell growth of MCF-7 breast cancer cells. The design of the analogs was based upon a cursory Topliss approach in which one of NDGA's aromatic rings was modified with various substituents. Structural modification of one of the two catechol rings of NDGA was found to have little effect upon the inhibitory potency against both kinase activity of the IGF-1R and IGF-1 mediated cell growth of MCF-7 cells. 15-LOX was found to be most sensitive to structural modifications of NDGA. From the limited series of NDGA analogs examined, the compound that exhibited the greatest selectivity for IGF-1 mediated growth compared to 15-LOX inhibition was a cyclic analog 7h with a framework similar to a natural product isolated from Larrea divaricata. The results for 7h are significant because while NDGA displays biological promiscuity, 7h exhibits greater specificity toward the breast cancer target IGF-1R with that added benefit of possessing a 10-fold weaker potency against 15-LOX, an enzyme which has a purported tumor suppressing role in breast cancer. With increased specificity and potency, 7h may serve as a new lead in developing novel therapeutic agents for breast cancer.
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"Nordihydroguaiaretic acid (NDGA), the main metabolite of the creosote bush, has shown to have promising applications in the treatment of multiple diseases . NDGA was recently shown to inhibit several receptor tyrosine kinases, including insulin-like growth factor (IGF-1) receptor [22, 23], c-erbB2/HER2/neu (HER2/neu) receptor [23, 24], and fibroblast growth factor receptor-3 . NDGA likely exerts its anti-cancer activity in part through inhibiting these tumor-promoting receptor tyrosine kinases. "
[Show abstract][Hide abstract]ABSTRACT: Accumulating evidence suggests that high expression of FGFR1 is closely related to the development of lung cancer especially in non-small cell lung cancers (NSCLC), to which non-ATP competitive inhibitors represent an effective therapeutical approach due to their good specificity. Herein, a series of NDGA analogues with the framework of bisaryl-1,4-dien-3-one as novel FGFR1 inhibitors have been designed and screened. Among them Aea4 and Aea25 showed strong FGFR1`inhibition and high selectivity over other receptor kinases. The kinase inhibitory assay in different ATP concentrations and computer-assistant molecular docking showed that the FGFR1 inhibition mode of both Aea4 and Aea25 was non-ATP-competitive. The in vitro and in vivo study on anticancer efficacy of Aea4 and Aea25 against non-small cell lung cancer involves inhibition of cell proliferation, apoptosis induction and cell cycle arrest with no toxicity. Thus, these two novel non-ATP competitive inhibitors derived from NDGA may have a great therapeutic potential in the treatment of NSCLC. This work also provides a structural lead for the design of new non-ATP-competitive FGFR1 inhibitors.
"For example, CP-7518717, a fully human monoclonal antibody specific for IGF1R, is in phase III clinical trial as a component of combination therapies for the treatment of non-small cell lung cancer (NSCLC). Nordihydroguaiaretic acid Insm-18/NGDA8, a dual inhibitor of IGF1R and human epidermal growth factor receptor 2 (HER2), is in phase II clinical trial for the treatment of prostate cancer. In addition, several small molecule IGF1R inhibitors are currently in clinical or preclinical development, including picropodophyllin (PPP)9, NVP-AEW54110, AG-102411, BMS-53694212, BMS-55441713, and NVP-ADW74214. "
[Show abstract][Hide abstract]ABSTRACT: The insulin-like growth factor-1 receptor (IGF1R) is over-expressed in a wide variety of tumors and contributes to tumor cell proliferation, metastasis and drug resistance. The aim of this study was to establish a sensitive screening platform to identify novel IGF1R inhibitors.
The catalytic domain of IGF1R was expressed using the Bac-to-Bac baculovirus expression system. The screening platform for IGF1R inhibitors was established based on ELISA. The binding profile of IGF1R with the inhibitors was predicted with molecular docking and then subjected to the surface plasmon resonance (SPR) approach. The growth inhibition of cancer cells by the inhibitors was assessed with MTT assay. Apoptosis was analyzed using flow cytometry and Western blotting.
A naturally occurring small molecule compound hematoxylin was identified as the most potent inhibitor (IC₅₀ value=1.8±0.1 μmol/L) within a library of more than 200 compounds tested. Molecular simulation predicted the possible binding mode of hematoxylin with IGF1R. An SPR assay further confirmed that hematoxylin bound directly to IGF1R with high binding affinity (Kd=4.2 × 10⁻⁶ mol/L). In HL-60 cancer cells, hematoxylin inactivated the phosphorylation of IGF1R and downstream signaling and therefore suppressed cell proliferation. Mechanistic studies revealed that hematoxylin induced apoptosis in HL-60 cells via both extrinsic and intrinsic pathways.
A simple, sensitive ELISA-based screening platform for identifying IGF1R inhibitors was established. Hematoxylin was identified as a promising IGF1R inhibitor with effective antitumor activity that deserves further investigation.
Full-text · Article · Jun 2011 · Acta Pharmacologica Sinica
"These findings indicate that the structure of NDGA can be refined to achieve higher potency against TGF-β, and that a compound with a single catechol ring is likely to show improved performance against this target. Interestingly, the asymmetrical compounds tested in the present study that showed increased potency against TGF-β signaling were reported in our previous publication to show improved growth inhibition of breast cancer cells compared to NDGA (Blecha et al., 2007). "
[Show abstract][Hide abstract]ABSTRACT: It has been well documented that nordihydroguaiaretic acid (NDGA), a phenolic lignan isolated from the creosote bush, Larrea tridentate, has anti-cancer activity in vitro and in vivo. Several mechanisms have been identified that could contribute to these actions, as NDGA directly inhibits metabolic enzymes and receptor tyrosine kinases that are established anti-cancer targets. In the present study, we show that NDGA inhibits the transforming growth factor beta (TGF-beta) type I receptor, a serine threonine kinase receptor. In cultured cells, NDGA treatment repressed Smad2 phosphorylation induced by TGF-beta treatment and by a constitutively active mutant of TGF-beta type I receptor (T202D). NDGA also inhibited downstream transcriptional activation mediated by both TGF-beta treatment and the constitutively active mutant receptor. In vitro, NDGA inhibited TGF-beta type I receptor mediated Smad2 phosphorylation in crude cell lysates and in a purified preparation. Importantly, screening select analogs demonstrated that modification of NDGA's structure resulted in altered potency against the receptor. These results indicated that the structure of NDGA can be modified to achieve increased potency. Together our data provide a novel mechanism for NDGA activity which could help explain its anti-cancer activity, and suggest that NDGA could serve as a structural motif for developing serine/threonine kinase inhibitors with selectivity for TGF-beta type I receptor.
Preview · Article · Jul 2009 · European journal of pharmacology