Specific IKKbeta inhibitor IV blocks Streptonigrin-induced NF-kappaB activity and potentiates its cytotoxic effect on cancer cells.
ABSTRACT Many anticancer agents activate NF-kappaB, which plays an important role in the survival of cancer cells. Inhibition of NF-kappaB activity may therefore potentiate the efficacy of anticancer agents. We found that a previously used anticancer agent Streptonigrin (SN) was also a potent NF-kappaB inducer. Using a specific IKKbeta inhibitor IV (Podolin et al., J Pharmacol Exp Ther 2005; 312: 373-381), we revealed that the activation of NF-kappaB was mediated through DNA damage-induced activation of IKK complex. Furthermore, we demonstrated that SN-induced DNA damage was unrelated to reactive oxygen species but to the hydroquinone form of SN converted by the NAD(P)H:quinine oxidoreductase (NQO1). The study suggests that the combination of SN with IKK inhibitor may improve efficacy over the use of single agent.
- SourceAvailable from: Malgorzata Czyz
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- "Streptonigrin is converted by NAD(P)H:quinine oxidoreductase (NQO1) to the more active hydroquinone form. Therefore, tumors containing high levels of this enzyme might be sensitive to streptonigrin at concentrations that do not generate severe side effects . It was also shown that streptonigrin at 0.05 µM markedly decreased clonogenic survival of pancreatic cancer cells expressing NQO1 at elevated levels but not of colorectal cancer cells with lower levels of this enzyme . "
ABSTRACT: Accumulating evidence supports the concept that melanoma is highly heterogeneous and sustained by a small subpopulation of melanoma stem-like cells. Those cells are considered as responsible for tumor resistance to therapies. Moreover, melanoma cells are characterized by their high phenotypic plasticity. Consequently, both melanoma stem-like cells and their more differentiated progeny must be eradicated to achieve durable cure. By reevaluating compounds in heterogeneous melanoma populations, it might be possible to select compounds with activity not only against fast-cycling cells but also against cancer stem-like cells. Natural compounds were the focus of the present study. We analyzed 120 compounds from The Natural Products Set II to identify compounds active against melanoma populations grown in an anchorage-independent manner and enriched with cells exerting self-renewing capacity. Cell viability, cell cycle arrest, apoptosis, gene expression, clonogenic survival and label-retention were analyzed. Several compounds efficiently eradicated cells with clonogenic capacity and nanaomycin A, streptonigrin and toyocamycin were effective at 0.1 µM. Other anti-clonogenic but not highly cytotoxic compounds such as bryostatin 1, siomycin A, illudin M, michellamine B and pentoxifylline markedly reduced the frequency of ABCB5 (ATP-binding cassette, sub-family B, member 5)-positive cells. On the contrary, treatment with maytansine and colchicine selected for cells expressing this transporter. Maytansine, streptonigrin, toyocamycin and colchicine, even if highly cytotoxic, left a small subpopulation of slow-dividing cells unaffected. Compounds selected in the present study differentially altered the expression of melanocyte/melanoma specific microphthalmia-associated transcription factor (MITF) and proto-oncogene c-MYC. Selected anti-clonogenic compounds might be further investigated as potential adjuvants targeting melanoma stem-like cells in the combined anti-melanoma therapy, whereas selected cytotoxic but not anti-clonogenic compounds, which increased the frequency of ABCB5-positive cells and remained slow-cycling cells unaffected, might be considered as a tool to enrich cultures with cells exhibiting melanoma stem cell characteristics.PLoS ONE 03/2014; 9(3):e90783. DOI:10.1371/journal.pone.0090783 · 3.23 Impact Factor
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ABSTRACT: A series of tricyclic anilinopyrimidines were synthesized and evaluated as IKKbeta inhibitors. Several analogues, including tricyclic phenyl (10, 18a, 18c, 18d, and 18j) and thienyl (26 and 28) derivatives were shown to have good in vitro enzyme potency and excellent cellular activity. Pharmaceutical profiling of a select group of tricyclic compounds compared to the non-tricyclic analogues suggested that in some cases, the improved cellular activity may be due to increased clog P and permeability.Bioorganic & medicinal chemistry letters 06/2010; 20(12):3821-5. DOI:10.1016/j.bmcl.2010.04.022 · 2.33 Impact Factor
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ABSTRACT: Various inflammatory stimuli that activate the nuclear factor kappa B (NF-κB) signaling pathway converge on a serine/threonine kinase that displays a key role in the activation of NF-κB: the I kappa B kinase β (IKK-β). Therefore, IKK-β is considered an interesting target for combating inflammation and cancer. In our study, we developed a ligand-based pharmacophore model for IKK-β inhibitors. This model was employed to virtually screen commercial databases, giving a focused hit list of candidates. Subsequently, we scored by molecular shape to rank and further prioritized virtual hits by three-dimensional shape-based alignment. One out of ten acquired and biologically tested compounds showed inhibitory activity in the low micromolar range on IKK-β enzymatic activity in vitro and on NF-κB transactivation in intact cells. Compound 8 (2-(1-adamantyl)ethyl 4-[(2,5-dihydroxyphenyl)methylamino]benzoate) represents a novel chemical class of IKK-β inhibitors and shows that the presented model is a valid approach for identification and development of new IKK-β ligands.Bioorganic & medicinal chemistry letters 10/2010; 21(1):577-83. DOI:10.1016/j.bmcl.2010.10.051 · 2.33 Impact Factor