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Inhibition of casein kinase 1-epsilon induces cancer-cell-selective, PERIOD2-dependent growth arrest.

Yang WS, Stockwell BR - Genome Biol. (2008)

Bottom Line: We employed a two-step screening strategy using human sarcoma cell lines and human fibroblast-derived isogenic cell lines, and found that short hairpin RNAs targeting CSNK1E, a clock gene that regulates circadian rhythms, can induce selective growth inhibition in engineered tumor cells.Treatment with IC261, a kinase domain inhibitor of casein kinase 1-epsilon (CK1epsilon), a protein product of CSNK1E, showed a similar degree of cancer-cell-selective growth inhibition.These data support the hypothesis that circadian clock genes can control the cell cycle and cell survival signaling, and emphasize a central role of CK1epsilon and PERIOD2 in linking these systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Columbia University, Fairchild Center, Amsterdam Avenue, New York, NY 10027, USA.

ABSTRACT

Background: Kinases are under extensive investigation as targets for drug development. Discovering novel kinases whose inhibition induces cancer-cell-selective lethality would be of value. Recent advances in RNA interference have enabled the realization of this goal.

Results: We screened 5,760 short hairpin RNA clones targeting the human kinome to detect human kinases on which cancer cells are more dependent than normal cells. We employed a two-step screening strategy using human sarcoma cell lines and human fibroblast-derived isogenic cell lines, and found that short hairpin RNAs targeting CSNK1E, a clock gene that regulates circadian rhythms, can induce selective growth inhibition in engineered tumor cells. Analysis of gene-expression data revealed that CSNK1E is overexpressed in several cancer tissue samples examined compared to non-tumorigenic normal tissue, suggesting a positive role of CSNK1E in neogenesis or maintenance. Treatment with IC261, a kinase domain inhibitor of casein kinase 1-epsilon (CK1epsilon), a protein product of CSNK1E, showed a similar degree of cancer-cell-selective growth inhibition. In a search for substrates of CK1epsilon that mediate IC261-induced growth inhibition, we discovered that knocking down PER2, another clock gene involved in circadian rhythm control, rescues IC261-induced growth inhibition.

Conclusion: We identified CK1epsilon as a potential target for developing anticancer reagents with a high therapeutic index. These data support the hypothesis that circadian clock genes can control the cell cycle and cell survival signaling, and emphasize a central role of CK1epsilon and PERIOD2 in linking these systems.

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CSNK1E is a target for developing anti-cancer drugs with a potentially high therapeutic index. (a) Retesting of six hit shRNA clones in isogenic BJ-derived cell lines. Knocking down CSNK1E induced cancer-cell-specific growth inhibition, whereas knocking down other survival genes did not display differential activity in the two cell lines. The graph is representative of multiple experiments. (b) The activity of shCSNK1E was examined in four isogenic BJ-derived cell lines. The growth inhibitory effect of shCSNK1E was proportional to the cell proliferation rate. The doubling time of each cell line is shown in parentheses. (c) Inhibition of HT1080 cell growth by independent shRNA clones that bind to different regions of CSNK1E mRNA. (d) The knockdown efficiency of each shRNA clone targeting CSNK1E as assessed by quantitative PCR analysis. Error bars in (b-d) indicate one standard deviation of triplicate data.
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Figure 2: CSNK1E is a target for developing anti-cancer drugs with a potentially high therapeutic index. (a) Retesting of six hit shRNA clones in isogenic BJ-derived cell lines. Knocking down CSNK1E induced cancer-cell-specific growth inhibition, whereas knocking down other survival genes did not display differential activity in the two cell lines. The graph is representative of multiple experiments. (b) The activity of shCSNK1E was examined in four isogenic BJ-derived cell lines. The growth inhibitory effect of shCSNK1E was proportional to the cell proliferation rate. The doubling time of each cell line is shown in parentheses. (c) Inhibition of HT1080 cell growth by independent shRNA clones that bind to different regions of CSNK1E mRNA. (d) The knockdown efficiency of each shRNA clone targeting CSNK1E as assessed by quantitative PCR analysis. Error bars in (b-d) indicate one standard deviation of triplicate data.

Mentions: Out of these six shRNA clones, five did not show differential activity in the two cell lines; however, the shRNA targeting CSNK1E (hereafter, shCSNK1E) had a tumorigenic-cell-line-specific activity (Figure 2a). The activity of shCSNK1E was further tested in four different BJ-derived cell lines, namely, BJ-TERT, BJ-TERT/LT/ST, BJ-TERT/LT/ST/RASV12, and DRD cells. DRD cells were engineered to express hTERT, ST, HRASG12V, dominant negative p53, and constitutively active cyclin-dependent kinase (CDK)4/cyclin D, which inactivates the RB protein [17]. The p53DD/CDK4/cyclin D1 combinations substitute for LT. DRD cells are tumorigenic in nude mice, which is expected from the fact that they are also derived from BJ primary cells and the effects of mutations in both cell lines should be similar. The growth inhibitory potential of shCSNK1E increased as the cell doubling time decreased, suggesting that the activity is proliferation-rate dependent rather than genotype dependent (Figure 2b).


Inhibition of casein kinase 1-epsilon induces cancer-cell-selective, PERIOD2-dependent growth arrest.

Yang WS, Stockwell BR - Genome Biol. (2008)

CSNK1E is a target for developing anti-cancer drugs with a potentially high therapeutic index. (a) Retesting of six hit shRNA clones in isogenic BJ-derived cell lines. Knocking down CSNK1E induced cancer-cell-specific growth inhibition, whereas knocking down other survival genes did not display differential activity in the two cell lines. The graph is representative of multiple experiments. (b) The activity of shCSNK1E was examined in four isogenic BJ-derived cell lines. The growth inhibitory effect of shCSNK1E was proportional to the cell proliferation rate. The doubling time of each cell line is shown in parentheses. (c) Inhibition of HT1080 cell growth by independent shRNA clones that bind to different regions of CSNK1E mRNA. (d) The knockdown efficiency of each shRNA clone targeting CSNK1E as assessed by quantitative PCR analysis. Error bars in (b-d) indicate one standard deviation of triplicate data.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2481424&req=5

Figure 2: CSNK1E is a target for developing anti-cancer drugs with a potentially high therapeutic index. (a) Retesting of six hit shRNA clones in isogenic BJ-derived cell lines. Knocking down CSNK1E induced cancer-cell-specific growth inhibition, whereas knocking down other survival genes did not display differential activity in the two cell lines. The graph is representative of multiple experiments. (b) The activity of shCSNK1E was examined in four isogenic BJ-derived cell lines. The growth inhibitory effect of shCSNK1E was proportional to the cell proliferation rate. The doubling time of each cell line is shown in parentheses. (c) Inhibition of HT1080 cell growth by independent shRNA clones that bind to different regions of CSNK1E mRNA. (d) The knockdown efficiency of each shRNA clone targeting CSNK1E as assessed by quantitative PCR analysis. Error bars in (b-d) indicate one standard deviation of triplicate data.
Mentions: Out of these six shRNA clones, five did not show differential activity in the two cell lines; however, the shRNA targeting CSNK1E (hereafter, shCSNK1E) had a tumorigenic-cell-line-specific activity (Figure 2a). The activity of shCSNK1E was further tested in four different BJ-derived cell lines, namely, BJ-TERT, BJ-TERT/LT/ST, BJ-TERT/LT/ST/RASV12, and DRD cells. DRD cells were engineered to express hTERT, ST, HRASG12V, dominant negative p53, and constitutively active cyclin-dependent kinase (CDK)4/cyclin D, which inactivates the RB protein [17]. The p53DD/CDK4/cyclin D1 combinations substitute for LT. DRD cells are tumorigenic in nude mice, which is expected from the fact that they are also derived from BJ primary cells and the effects of mutations in both cell lines should be similar. The growth inhibitory potential of shCSNK1E increased as the cell doubling time decreased, suggesting that the activity is proliferation-rate dependent rather than genotype dependent (Figure 2b).

Bottom Line: We employed a two-step screening strategy using human sarcoma cell lines and human fibroblast-derived isogenic cell lines, and found that short hairpin RNAs targeting CSNK1E, a clock gene that regulates circadian rhythms, can induce selective growth inhibition in engineered tumor cells.Treatment with IC261, a kinase domain inhibitor of casein kinase 1-epsilon (CK1epsilon), a protein product of CSNK1E, showed a similar degree of cancer-cell-selective growth inhibition.These data support the hypothesis that circadian clock genes can control the cell cycle and cell survival signaling, and emphasize a central role of CK1epsilon and PERIOD2 in linking these systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Columbia University, Fairchild Center, Amsterdam Avenue, New York, NY 10027, USA.

ABSTRACT

Background: Kinases are under extensive investigation as targets for drug development. Discovering novel kinases whose inhibition induces cancer-cell-selective lethality would be of value. Recent advances in RNA interference have enabled the realization of this goal.

Results: We screened 5,760 short hairpin RNA clones targeting the human kinome to detect human kinases on which cancer cells are more dependent than normal cells. We employed a two-step screening strategy using human sarcoma cell lines and human fibroblast-derived isogenic cell lines, and found that short hairpin RNAs targeting CSNK1E, a clock gene that regulates circadian rhythms, can induce selective growth inhibition in engineered tumor cells. Analysis of gene-expression data revealed that CSNK1E is overexpressed in several cancer tissue samples examined compared to non-tumorigenic normal tissue, suggesting a positive role of CSNK1E in neogenesis or maintenance. Treatment with IC261, a kinase domain inhibitor of casein kinase 1-epsilon (CK1epsilon), a protein product of CSNK1E, showed a similar degree of cancer-cell-selective growth inhibition. In a search for substrates of CK1epsilon that mediate IC261-induced growth inhibition, we discovered that knocking down PER2, another clock gene involved in circadian rhythm control, rescues IC261-induced growth inhibition.

Conclusion: We identified CK1epsilon as a potential target for developing anticancer reagents with a high therapeutic index. These data support the hypothesis that circadian clock genes can control the cell cycle and cell survival signaling, and emphasize a central role of CK1epsilon and PERIOD2 in linking these systems.

Show MeSH
Related in: MedlinePlus