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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 compounds plate 4 on HCT116 cells proliferation and in-vitro inhibition effects of selected compounds on CK2 kinase activity. A. After incubation with HCT116 cells for 48 hours, compounds 4A3 (hematein), 4A6 and 4A9 showed inhibitory effects on cell proliferation compared to the control sample (*4A1, DMSO). The longitudinal values revealed the absorbance at 490 nm recorded using an ELISA plate reader after addition of Cell Titer 96 AQueous One Solution Reagent to each well for 2 hours. Data represents the average of duplicate wells and bars indicate SD. Compound concentration: 4A3: 16.6 μM; 4A6: 23.1 μM; 4A9: 14.2 μM. B. Equal amounts (100 μM) of compounds were incubated with purified CK2, and CK2 activity was measured by Cyclex CK2 Assay/Inhibitor Screening Kit using 100 μM ATP. Ck2 kinase activity is represented as relative CK2 activity to controls (DMSO). Data represents the average of duplicate wells and bars indicate SD.4A3: hematein. Other negative results are not shown.
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Figure 1: Inhibition effects of compounds plate 4 on HCT116 cells proliferation and in-vitro inhibition effects of selected compounds on CK2 kinase activity. A. After incubation with HCT116 cells for 48 hours, compounds 4A3 (hematein), 4A6 and 4A9 showed inhibitory effects on cell proliferation compared to the control sample (*4A1, DMSO). The longitudinal values revealed the absorbance at 490 nm recorded using an ELISA plate reader after addition of Cell Titer 96 AQueous One Solution Reagent to each well for 2 hours. Data represents the average of duplicate wells and bars indicate SD. Compound concentration: 4A3: 16.6 μM; 4A6: 23.1 μM; 4A9: 14.2 μM. B. Equal amounts (100 μM) of compounds were incubated with purified CK2, and CK2 activity was measured by Cyclex CK2 Assay/Inhibitor Screening Kit using 100 μM ATP. Ck2 kinase activity is represented as relative CK2 activity to controls (DMSO). Data represents the average of duplicate wells and bars indicate SD.4A3: hematein. Other negative results are not shown.

Mentions: First, a cell based MTS cell proliferation assay was used to evaluate the inhibitory effects of 400 compounds from NPL compound library on cell proliferation of HCT116 cells. HCT116 cell was selected for initial screening because previous studies showed that this cell line was inhibited by CK2 inhibitors[17,18]. After incubation for 48 hours in 96-wells plates, a number of compounds including 4A3, 4A6 and 4A9, showed inhibition effects on HCT116 cells proliferation compared to control samples (DMSO) (Fig 1A).


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 compounds plate 4 on HCT116 cells proliferation and in-vitro inhibition effects of selected compounds on CK2 kinase activity. A. After incubation with HCT116 cells for 48 hours, compounds 4A3 (hematein), 4A6 and 4A9 showed inhibitory effects on cell proliferation compared to the control sample (*4A1, DMSO). The longitudinal values revealed the absorbance at 490 nm recorded using an ELISA plate reader after addition of Cell Titer 96 AQueous One Solution Reagent to each well for 2 hours. Data represents the average of duplicate wells and bars indicate SD. Compound concentration: 4A3: 16.6 μM; 4A6: 23.1 μM; 4A9: 14.2 μM. B. Equal amounts (100 μM) of compounds were incubated with purified CK2, and CK2 activity was measured by Cyclex CK2 Assay/Inhibitor Screening Kit using 100 μM ATP. Ck2 kinase activity is represented as relative CK2 activity to controls (DMSO). Data represents the average of duplicate wells and bars indicate SD.4A3: hematein. Other negative results are not shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2696466&req=5

Figure 1: Inhibition effects of compounds plate 4 on HCT116 cells proliferation and in-vitro inhibition effects of selected compounds on CK2 kinase activity. A. After incubation with HCT116 cells for 48 hours, compounds 4A3 (hematein), 4A6 and 4A9 showed inhibitory effects on cell proliferation compared to the control sample (*4A1, DMSO). The longitudinal values revealed the absorbance at 490 nm recorded using an ELISA plate reader after addition of Cell Titer 96 AQueous One Solution Reagent to each well for 2 hours. Data represents the average of duplicate wells and bars indicate SD. Compound concentration: 4A3: 16.6 μM; 4A6: 23.1 μM; 4A9: 14.2 μM. B. Equal amounts (100 μM) of compounds were incubated with purified CK2, and CK2 activity was measured by Cyclex CK2 Assay/Inhibitor Screening Kit using 100 μM ATP. Ck2 kinase activity is represented as relative CK2 activity to controls (DMSO). Data represents the average of duplicate wells and bars indicate SD.4A3: hematein. Other negative results are not shown.
Mentions: First, a cell based MTS cell proliferation assay was used to evaluate the inhibitory effects of 400 compounds from NPL compound library on cell proliferation of HCT116 cells. HCT116 cell was selected for initial screening because previous studies showed that this cell line was inhibited by CK2 inhibitors[17,18]. After incubation for 48 hours in 96-wells plates, a number of compounds including 4A3, 4A6 and 4A9, showed inhibition effects on HCT116 cells proliferation compared to control samples (DMSO) (Fig 1A).

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