The novel BH3 α-helix mimetic JY-1-106 induces apoptosis in a subset of cancer cells (lung cancer, colon cancer and mesothelioma) by disrupting Bcl-xL and Mcl-1 protein-protein interactions with Bak

Our plain-English summary of The novel BH3 α-helix mimetic JY-1-106 induces apoptosis in a subset of cancer cells (lung cancer, colon cancer and mesothelioma) by disrupting Bcl-xL and Mcl-1 protein-protein interactions with Bak, by X. Cao, J.L. Yap, M.K. Newell-Rogers, et al (Molecular Cancer, 2013).

The study

• Authors: X. Cao, J.L. Yap, M.K. Newell-Rogers, C. Peddaboina, W. Jiang, H.T. Papaconstantinou, D. Jupitor, A. Rai, K.Y. Jung, R.P. Tubin, W. Yu, K. Vanommeslaeghe, P.T. Wilder, A.D. MacKerell, S. Fletcher, R.W. Smythe
• Journal: Molecular Cancer
• Published: 2013;12(1):42
• Cited by: 70 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: It has been shown in many solid tumors that the overexpression of the pro-survival Bcl-2 family members Bcl-2/Bcl-xL and Mcl-1 confers resistance to a variety of chemotherapeutic agents. We designed the BH3 α-helix mimetic JY-1-106 to engage the hydrophobic BH3-binding grooves on the surfaces of both Bcl-xL and Mcl-1.

Methods: JY-1-106-protein complexes were studied using molecular dynamics (MD) simulations and the SILCS methodology. We have evaluated the in vitro effects of JY-1-106 by using a fluorescence polarization (FP) assay, an XTT assay, apoptosis assays, and immunoprecipitation and western-blot assays. A preclinical human cancer xenograft model was used to test the efficacy of JY-1-106 in vivo.

Results: MD and SILCS simulations of the JY-1-106-protein complexes indicated the importance of the aliphatic side chains of JY-1-106 to binding and successfully predicted the improved affinity of the ligand for Bcl-xL over Mcl-1. Ligand binding affinities were measured via an FP assay using a fluorescently labeled Bak-BH3 peptide in vitro. Apoptosis induction via JY-1-106 was evidenced by TUNEL assay and PARP cleavage as well as by Bax-Bax dimerization. Release of multi-domain Bak from its inhibitory binding to Bcl-2/Bcl-xL and Mcl-1 using JY-1-106 was detected via immunoprecipitation (IP) western blotting.At the cellular level, we compared the growth proliferation IC50s of JY-1-106 and ABT-737 in multiple cancer cell lines with various Bcl-xL and Mcl-1 expression levels. JY-1-106 effectively induced cell death regardless of the Mcl-1 expression level in ABT-737 resistant solid tumor cells, whilst toxicity toward normal human endothelial cells was limited. Furthermore, synergistic effects were observed in A549 cells using a combination of JY-1-106 and multiple chemotherapeutic agents. We also observed that JY-1-106 was a very effective agent in inducing apoptosis in metabolically stressed tumors. Finally, JY-1-106 was evaluated in a tumor-bearing nude mouse model, and was found to effectively repress tumor growth. Strong TUNEL signals in the tumor cells demonstrated the effectiveness of JY-1-106 in this animal model. No significant side effects were observed in mouse organs after multiple injections.

Conclusions: Taken together, these observations demonstrate that JY-1-106 is an effective pan-Bcl-2 inhibitor with very promising clinical potential.

In plain English

This laboratory study characterized JY-1-106, a synthetic BH3 alpha-helix mimetic built on a trisarylamide scaffold, combining molecular dynamics and SILCS computer simulations, cell-culture assays and a mouse xenograft experiment. Simulations predicted more favourable binding to Bcl-xL than to Mcl-1 (ligand grid free energy differences of 2 to 8 kcal/mol depending on method). In a fluorescence polarization assay with a FITC-labelled Bak-BH3 peptide, the authors measured an IC50 of 10.21 plus or minus 0.83 micromolar for Mcl-1, citing a previously published IC50 of 394 plus or minus 54 nM for Bcl-xL. Immunoprecipitation western blotting in REN mesothelioma cells showed JY-1-106 displaced Bak from both Bcl-xL and Mcl-1, whereas ABT-737 displaced Bak only from Bcl-xL. Cell lines tested included two human mesothelioma lines (I45, REN), lung cancer lines (A549, H1299, H23) and colon cancer lines (DLD-1, HCT116). At 20 micromolar, JY-1-106 caused less than 20% growth inhibition in normal human microvascular endothelial cells. In nude mice with A549 flank tumours, JY-1-106 inhibited tumour growth compared with vehicle (ANOVA, p less than 0.05).

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study combining computational molecular dynamics/SILCS simulations, in vitro biochemical and cell-culture assays, and a mouse tumour xenograft experiment
• Who was studied: Human cancer cell lines (mesothelioma I45 and REN; lung cancer A549, H1299, H23; colon cancer DLD-1, HCT116), normal human microvascular endothelial cells, and female nude mice bearing A549 xenografts (n = 6 per group)
• Exposure: Treatment with the BH3 alpha-helix mimetic JY-1-106 (typically 5 micromolar in cells; 25 mg/kg intraperitoneally in mice), compared with ABT-737, cisplatin, SAHA, Taxol and metabolic stress
• Main results:
  • In the fluorescence polarization assay, the IC50 for inhibition of the FITC-Bak-BH3 peptide interaction with Mcl-1 was 10.21 plus or minus 0.83 micromolar (Figure 2A); the Bcl-xL value of 394 plus or minus 54 nM is cited to an earlier publication by the authors (reference 15)
  • Ki values given were 179 plus or minus 24 nM for Bcl-xL and 1.79 plus or minus 0.15 micromolar for Mcl-1, about a ten-fold difference
  • In REN mesothelioma cells, JY-1-106 but not ABT-737 displaced Bak from Mcl-1; both displaced Bak from Bcl-xL
  • SILCS calculations predicted more favourable binding to Bcl-xL than Mcl-1 by 2 to 8 kcal/mol
  • In normal human microvascular endothelial cells, JY-1-106 at 20 micromolar caused less than 20% growth inhibition and no apoptosis by TUNEL
  • In A549 cells, combinations of Taxol and JY-1-106 gave combination index values indicating synergy at all doses examined
  • In nude mice with A549 flank xenografts, JY-1-106 inhibited tumour growth compared with vehicle control
  • No gross toxicity, no significant pathologic lesions in liver, kidney, lung and spleen, and normal BUN/creatinine and liver enzymes in treated mice
• The authors' conclusion: The authors concluded that JY-1-106 is an effective pan-Bcl-2 inhibitor showing single-agent activity in multiple human cancer cells and an animal tumour model, and that it warrants further evaluation as a novel anti-cancer drug

Topics

The National Library of Medicine indexes this study under subjects our site covers: Colon cancer, Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Apoptosis, Lung Cancer, Colorectal Cancer, Mesothelioma, Synergistic Effect, A549 Cells.

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