Identification of a selective small molecule inhibitor of breast cancer stem cells
ABSTRACT A high-throughput screen (HTS) with the National Institute of Health-Molecular Libraries Small Molecule Repository (NIH-MLSMR) compound collection identified a class of acyl hydrazones to be selectively lethal to breast cancer stem cell (CSC) enriched populations. Medicinal chemistry efforts were undertaken to optimize potency and selectivity of this class of compounds. The optimized compound was declared as a probe (ML239) with the NIH Molecular Libraries Program and displayed greater than 20-fold selective inhibition of the breast CSC-like cell line (HMLE_sh_Ecad) over the isogenic control line (HMLE_sh_GFP).
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ABSTRACT: Cancer stem cells (CSCs) are resistant to standard cancer treatments and are likely responsible for cancer recurrence, but few therapies target this subpopulation. Due to the difficulty in propagating CSCs outside of the tumor environment, previous work identified CSC-like cells by inducing human breast epithelial cells into an epithelial-to-mesenchymal transdifferentiated state (HMLE_sh_ECad). A phenotypic screen was conducted against HMLE_sh_ECad with 300 718 compounds from the Molecular Libraries Small Molecule Repository to identify selective inhibitors of CSC growth. The screen yielded 2244 hits that were evaluated for toxicity and selectivity toward an isogenic control cell line. An acyl hydrazone scaffold emerged as a potent and selective scaffold targeting HMLE_sh_ECad. Fifty-three analogues were acquired and tested; compounds ranged in potency from 790 nM to inactive against HMLE_sh_ECad. Of the analogues, ML239 was best-in-class with an IC(50)= 1.18 µM against HMLE_sh_ECad, demonstrated a >23-fold selectivity over the control line, and was toxic to another CSC-like line, HMLE_shTwist, and a breast carcinoma cell line, MDA-MB-231. Gene expression studies conducted with ML239-treated cells showed altered gene expression in the NF-κB pathway in the HMLE_sh_ECad line but not in the isogenic control line. Future studies will be directed toward the identification of ML239 target(s).Journal of Biomolecular Screening 08/2012; 17(9):1204-10. DOI:10.1177/1087057112458317 · 2.01 Impact Factor
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ABSTRACT: Cancer stem cells (CSCs) have been identified in a growing list of malignancies and are believed to be responsible for cancer initiation, metastasis and relapse following certain therapies, even though they may only represent a small fraction of the cells in a given cancer. Like somatic stem cells and embryonic stem cells, CSCs are capable of self-renewal and differentiation into more mature, less tumorigenic cells that make up the bulk populations of cancer cells. Elimination of CSCs promises intriguing therapeutic potential and this concept has been adopted in preclinical drug discovery programs. Herein we will discuss the progress of these efforts, general considerations in practice, major challenges and possible solutions.Future medicinal chemistry 09/2014; 6(14):1567-85. DOI:10.4155/fmc.14.106 · 4.00 Impact Factor
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ABSTRACT: Purpose: Epithelial-Mesenchymal Transition (EMT) features appear to be key events in development and progression of breast cancer. Epigenetic modifications contribute to the establishment and maintenance of cancer subclasses, as well as to the EMT process. Whether histone variants contribute to these transformations is not known. We investigated the relative expression levels of histone macroH2A1 splice variants and correlated it with breast cancer status/prognosis/types. Methods: To detect differential expression of macroH2A1 variant mRNAs in breast cancer cells and tumor samples, we used the following databases: GEO, EMBL-EBI and publisher databases (may-august 2012). We extracted macroH2A1.1/macroH2A1 mRNA ratios and performed correlation studies on intrinsic molecular subclasses of breast cancer and on molecular characteristics of EMT. Associations between molecular and survival data were determined. Results: We found increased macroH2A1.1/macroH2A1 mRNA ratios to be associated with the claudin-low intrinsic subtype in breast cancer cell lines. At the molecular level this association translates into a positive correlation between macroH2A1 ratios and molecular characteristics of the EMT process. Moreover, untreated Triple Negative Breast Cancers presenting a high macroH2A1.1 mRNA ratio exhibit a poor outcome. Conclusion: These results provide first evidence that macroH2A1.1 could be exploited as an actor in the maintenance of a transient cellular state in EMT progress towards metastatic development of breast tumors.PLoS ONE 06/2014; 9(6):e98930. DOI:10.1371/journal.pone.0098930 · 3.53 Impact Factor