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Anti-tumor activity and mechanism of action for a cyanoaziridine-derivative, AMP423

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Abstract

Purpose

Preclinical studies evaluated the anti-tumor activity and mechanism of action of AMP423, a naphthyl derivative of 2-cyanoaziridine-1-carboxamide with structural similarity to the pro-oxidant anti-tumor agent imexon.

Methods

The cytotoxic potency was evaluated in vitro against a variety of human cancer cell lines. Mechanism-of-action studies were performed in the human 8226/S myeloma cell line and its imexon-resistant variant, 8226/IM10. In vivo activity was evaluated against human myeloma and lymphoma xenografts in SCID mice. Pharmacokinetics and toxicology were investigated in non-tumor-bearing mice.

Results

The 72-h IC50s for all cell types ranged from 2 to 36 μM, across a wide variety of human cancer cell lines. AMP423 was active in SCID mice bearing 8226/S myeloma and SU-DHL-6 B-cell lymphoma tumors, with a median tumor growth delay (T−C) of 21 days (P = 0.0002) and 5 days (P = 0.004), respectively, and a median tumor growth inhibition (T/C) of 33.3% (P = 0.03) and 82% (P = 0.01), respectively. In non-tumor-bearing mice, AMP423 was not myelosuppressive. Mechanistic studies show that AMP423’s mode of cell death is a mixture of necrosis and apoptosis, with generation of reactive oxygen species, inhibition of protein synthesis, and a decrease in reduced sulfhydryl levels, but no alkylation of nucleophiles. Unlike its structural analog imexon, which causes cell cycle arrest in G2/M, AMP423 induces the accumulation of cells in S-phase.

Conclusions

AMP423 has pro-oxidant effects similar to imexon, has greater cytotoxic potency in vitro, and has anti-tumor activity in hematologic tumors in vivo.

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Acknowledgments

This study is supported in part by grants CA-017094, CA-115626, and CA-023074 from the National Cancer Institute, National Institutes of Health, Bethesda, MD, U.S.A. We thank the University of Arizona Chemical Synthesis Facility, and the University of Arizona Cancer Center Flow Cytometry Core Service, Experimental Mouse Shared Service, and the Biostatistical Core Service for their expertise.

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Authors and Affiliations

  1. The University of Arizona Cancer Center, College of Medicine, 1515 N. Campbell Avenue, Tucson, AZ, 85724-5024, USA

    Robert T. Dorr, Lee Wisner, Betty K. Samulitis & Terry H. Landowski

  2. AmpliMed Corporation, 4380 N. Campbell Avenue, Suite 205, Tucson, AZ, USA

    Robert T. Dorr & William A. Remers

Authors
  1. Robert T. Dorr
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  2. Lee Wisner
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  3. Betty K. Samulitis
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  4. Terry H. Landowski
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  5. William A. Remers
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Corresponding author

Correspondence to Robert T. Dorr.

Electronic supplementary material

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280_2011_1784_MOESM1_ESM.tif

Analysis of binding to cellular thiols by AMP423 and imexon in 8226/S and 8226/IM10 cells. Binding to cellular thiols was analyzed by concurrent CMFDA and PI staining after 48 h exposure to increasing concentrations of AMP423 or imexon. Non-viable cells, indicated by positive PI staining, were gated out and the remaining population of viable cells were analyzed for intracellular reduced thiol content. The percent of CMFDA positive, viable cells is shown. Results shown are mean ± SEM (n = 3) (TIF 148 kb)

280_2011_1784_MOESM2_ESM.tif

Analysis of reactive oxygen species (ROS) upon exposure to AMP423 or imexon in 8226/S and 8226/IM10 cells. The increase in reactive oxygen species seen in 8226/S cells (Figs A, B) or 8226/IM10 cells (Figs C, D) after 24 h (left) or 48 h (right). The percent of HE positive cells is shown. Results shown are mean ± SEM (n = 6) (TIFF 166 kb)

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Dorr, R.T., Wisner, L., Samulitis, B.K. et al. Anti-tumor activity and mechanism of action for a cyanoaziridine-derivative, AMP423. Cancer Chemother Pharmacol 69, 1039–1049 (2012). https://doi.org/10.1007/s00280-011-1784-8

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  • DOI: https://doi.org/10.1007/s00280-011-1784-8

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