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Identification of hematein as a novel inhibitor of protein kinase CK2 from a natural product library.

Hung MS, Xu Z, Lin YC, Mao JH, Yang CT, Chang PJ, Jablons DM, You L - BMC Cancer (2009)

Bottom Line: Hematein was identified as a novel CK2 inhibitor that is highly selective among a panel of kinases.In this study, we showed that hematein is a novel selective and cell permeable small molecule CK2 inhibitor.This compound may represent a promising class of CK2 inhibitors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California, San Francisco, CA 94115, USA. Ming-Szu.Hung@ucsfmedctr.org

ABSTRACT

Background: Casein kinase 2 (CK2) is dysregulated in various human cancers and is a promising target for cancer therapy. To date, there is no small molecular CK2 inhibitor in clinical trial yet. With the aim to identify novel CK2 inhibitors, we screened a natural product library.

Methods: We adopted cell-based proliferation and CK2 kinase assays to screen CK2 inhibitors from a natural compound library. Dose-dependent response of CK2 inhibitors in vitro was determined by a radioisotope kinase assay. Western blot analysis was used to evaluate down stream Akt phosphorylation and apoptosis. Apoptosis was also evaluated by annexin-V/propidium iodide (PI) labeling method using flow cytometry. Inhibition effects of CK2 inhibitors on the growth of cancer and normal cells were evaluated by cell proliferation and viability assays.

Results: Hematein was identified as a novel CK2 inhibitor that is highly selective among a panel of kinases. It appears to be an ATP non-competitive and partially reversible CK2 inhibitor with an IC50 value of 0.55 muM. In addition, hematein inhibited cancer cell growth partially through down-regulation of Akt phosphorylation and induced apoptosis in these cells. Furthermore, hematein exerted stronger inhibition effects on the growth of cancer cells than in normal cells.

Conclusion: In this study, we showed that hematein is a novel selective and cell permeable small molecule CK2 inhibitor. Hematein showed stronger growth inhibition effects to cancer cells when compared to normal cells. This compound may represent a promising class of CK2 inhibitors.

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Inhibition effects of hematein on cellular growth in normal and cancer cells. A. Normal (WI-38, CCL-211) and cancer (Hela, A549 and A427, HCT116) cells were cultured in the absence and in increasing concentrations of hematein (10 μM to 100 μM) as indicated. Cellular viability (normalized to DMSO control) was measured after 48 hours using CellTiter-Glo® Luminescent cell viability assay. Data points represent the average of IC50 value of hematein in triplet experiments and bars indicate SD. "*" denotes p < 0.05 when compared with IC50 values of CCL-211 cells and "†" denotes p < 0.05 when compared with IC50 values of WI-38 cells. B. CCL-211 cells were incubated in the absence and presence of 50 μM hematein for 48 hours. Block arrows indicate staining of the nucleus after hematein incubation. Original magnification: × 100.
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Figure 5: Inhibition effects of hematein on cellular growth in normal and cancer cells. A. Normal (WI-38, CCL-211) and cancer (Hela, A549 and A427, HCT116) cells were cultured in the absence and in increasing concentrations of hematein (10 μM to 100 μM) as indicated. Cellular viability (normalized to DMSO control) was measured after 48 hours using CellTiter-Glo® Luminescent cell viability assay. Data points represent the average of IC50 value of hematein in triplet experiments and bars indicate SD. "*" denotes p < 0.05 when compared with IC50 values of CCL-211 cells and "†" denotes p < 0.05 when compared with IC50 values of WI-38 cells. B. CCL-211 cells were incubated in the absence and presence of 50 μM hematein for 48 hours. Block arrows indicate staining of the nucleus after hematein incubation. Original magnification: × 100.

Mentions: Finally, we compared inhibition effects of hematein on normal and cancer cells. Cytotoxicity of hematein against normal and cancer cells was measured using the CellTiter-Glo luminescent cell viability assay (Promega, Madison, WI) to overcome the interference of hematein to MTS assay. Indicated cells were treated with different concentrations of hematein for 48 hours, and cell viability was measured by the CellTiter-Glo luminescent cell viability assay. From dose response curve, IC50 values were calculated in CCL-211 (118.3 ± 15.7 μM) and WI-38 (150.3 ± 26 μM) normal cells than in Hela (57.7 ± 3.4 μM), A549 (90.0 ± 3.8 μM), A427 (62.9 ± 1.7 μM) and HCT116 (100.4 ± 7.3 μM) cancer cells (Fig 5A). Significantly higher IC50 values (p < 0.05) were noted in CCL-211 cells compared to Hela, A549 and A427 cells, and in WI-38 cells compared to Hela, A549, A427 and HCT116 cells. As the result, hematein has stronger inhibition effects towards cancer cells. We also took the advantage of the staining property of hematein to observe whether normal cells uptake hematein and hematein nuclear staining was noted in cells after treated with 50 μM hematein for 48 hours (Fig 5B).


Identification of hematein as a novel inhibitor of protein kinase CK2 from a natural product library.

Hung MS, Xu Z, Lin YC, Mao JH, Yang CT, Chang PJ, Jablons DM, You L - BMC Cancer (2009)

Inhibition effects of hematein on cellular growth in normal and cancer cells. A. Normal (WI-38, CCL-211) and cancer (Hela, A549 and A427, HCT116) cells were cultured in the absence and in increasing concentrations of hematein (10 μM to 100 μM) as indicated. Cellular viability (normalized to DMSO control) was measured after 48 hours using CellTiter-Glo® Luminescent cell viability assay. Data points represent the average of IC50 value of hematein in triplet experiments and bars indicate SD. "*" denotes p < 0.05 when compared with IC50 values of CCL-211 cells and "†" denotes p < 0.05 when compared with IC50 values of WI-38 cells. B. CCL-211 cells were incubated in the absence and presence of 50 μM hematein for 48 hours. Block arrows indicate staining of the nucleus after hematein incubation. Original magnification: × 100.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2696466&req=5

Figure 5: Inhibition effects of hematein on cellular growth in normal and cancer cells. A. Normal (WI-38, CCL-211) and cancer (Hela, A549 and A427, HCT116) cells were cultured in the absence and in increasing concentrations of hematein (10 μM to 100 μM) as indicated. Cellular viability (normalized to DMSO control) was measured after 48 hours using CellTiter-Glo® Luminescent cell viability assay. Data points represent the average of IC50 value of hematein in triplet experiments and bars indicate SD. "*" denotes p < 0.05 when compared with IC50 values of CCL-211 cells and "†" denotes p < 0.05 when compared with IC50 values of WI-38 cells. B. CCL-211 cells were incubated in the absence and presence of 50 μM hematein for 48 hours. Block arrows indicate staining of the nucleus after hematein incubation. Original magnification: × 100.
Mentions: Finally, we compared inhibition effects of hematein on normal and cancer cells. Cytotoxicity of hematein against normal and cancer cells was measured using the CellTiter-Glo luminescent cell viability assay (Promega, Madison, WI) to overcome the interference of hematein to MTS assay. Indicated cells were treated with different concentrations of hematein for 48 hours, and cell viability was measured by the CellTiter-Glo luminescent cell viability assay. From dose response curve, IC50 values were calculated in CCL-211 (118.3 ± 15.7 μM) and WI-38 (150.3 ± 26 μM) normal cells than in Hela (57.7 ± 3.4 μM), A549 (90.0 ± 3.8 μM), A427 (62.9 ± 1.7 μM) and HCT116 (100.4 ± 7.3 μM) cancer cells (Fig 5A). Significantly higher IC50 values (p < 0.05) were noted in CCL-211 cells compared to Hela, A549 and A427 cells, and in WI-38 cells compared to Hela, A549, A427 and HCT116 cells. As the result, hematein has stronger inhibition effects towards cancer cells. We also took the advantage of the staining property of hematein to observe whether normal cells uptake hematein and hematein nuclear staining was noted in cells after treated with 50 μM hematein for 48 hours (Fig 5B).

Bottom Line: Hematein was identified as a novel CK2 inhibitor that is highly selective among a panel of kinases.In this study, we showed that hematein is a novel selective and cell permeable small molecule CK2 inhibitor.This compound may represent a promising class of CK2 inhibitors.

View Article: PubMed Central - HTML - PubMed

Affiliation: Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California, San Francisco, CA 94115, USA. Ming-Szu.Hung@ucsfmedctr.org

ABSTRACT

Background: Casein kinase 2 (CK2) is dysregulated in various human cancers and is a promising target for cancer therapy. To date, there is no small molecular CK2 inhibitor in clinical trial yet. With the aim to identify novel CK2 inhibitors, we screened a natural product library.

Methods: We adopted cell-based proliferation and CK2 kinase assays to screen CK2 inhibitors from a natural compound library. Dose-dependent response of CK2 inhibitors in vitro was determined by a radioisotope kinase assay. Western blot analysis was used to evaluate down stream Akt phosphorylation and apoptosis. Apoptosis was also evaluated by annexin-V/propidium iodide (PI) labeling method using flow cytometry. Inhibition effects of CK2 inhibitors on the growth of cancer and normal cells were evaluated by cell proliferation and viability assays.

Results: Hematein was identified as a novel CK2 inhibitor that is highly selective among a panel of kinases. It appears to be an ATP non-competitive and partially reversible CK2 inhibitor with an IC50 value of 0.55 muM. In addition, hematein inhibited cancer cell growth partially through down-regulation of Akt phosphorylation and induced apoptosis in these cells. Furthermore, hematein exerted stronger inhibition effects on the growth of cancer cells than in normal cells.

Conclusion: In this study, we showed that hematein is a novel selective and cell permeable small molecule CK2 inhibitor. Hematein showed stronger growth inhibition effects to cancer cells when compared to normal cells. This compound may represent a promising class of CK2 inhibitors.

Show MeSH
Related in: MedlinePlus