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Co-inhibition of polo-like kinase 1 and Aurora kinases promotes mitotic catastrophe.

Li J, Hong MJ, Chow JP, Man WY, Mak JP, Ma HT, Poon RY - Oncotarget (2015)

Bottom Line: Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536).We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells.Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Science, Center for Cancer Research, and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.

ABSTRACT
Mitosis is choreographed by a number of protein kinases including polo-like kinases and Aurora kinases. As these kinases are frequently dysregulated in cancers, small-molecule inhibitors have been developed for targeted anticancer therapies. Given that PLK1 and Aurora kinases possess both unique functions as well as co-regulate multiple mitotic events, whether pharmacological inhibition of these kinases together can enhance mitotic catastrophe remains an outstanding issue to be determined. Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536). We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells. Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells. These observations underscore the mechanism and potential benefits of targeting PLK1 and Aurora kinases to induce mitotic catastrophe in cancer cells.

No MeSH data available.


Related in: MedlinePlus

Loss of Aurora kinases disrupts PLK1 activity during mitosis(A) Depletion of AURKA impairs the activation of PLK1. HeLa cells were transfected with control siRNA, siAURKA, or siAURKB. The cells were enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting. CDC27 analysis was included as a marker of mitosis. The positions of the unphosphorylated and mitotic form of CDC27 are indicated. Uniform loading of lysates was confirmed by immunoblotting for actin. (B) Depletion of PLK1 does not affect the activation of AURKA or AURKB. HeLa cells were transfected with control siRNA or siPLK1, before enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting.
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Figure 1: Loss of Aurora kinases disrupts PLK1 activity during mitosis(A) Depletion of AURKA impairs the activation of PLK1. HeLa cells were transfected with control siRNA, siAURKA, or siAURKB. The cells were enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting. CDC27 analysis was included as a marker of mitosis. The positions of the unphosphorylated and mitotic form of CDC27 are indicated. Uniform loading of lysates was confirmed by immunoblotting for actin. (B) Depletion of PLK1 does not affect the activation of AURKA or AURKB. HeLa cells were transfected with control siRNA or siPLK1, before enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting.

Mentions: To determine the relationship between Aurora kinases and PLK1 during G2 phase and mitosis, we first downregulated the Aurora kinases using specific siRNAs. After HeLa cells were transfected with siRNAs against AURKA and AURKB (siAURKA and siAURKB respectively), they were synchronized at either G2 phase (using a double thymidine blockÔÇôrelease procedure) or mitosis (using a procedure involving nocodazole followed by mechanical shake-off). Lysates were prepared and the activity of PLK1 was determined through the level of PLK1Thr210 phosphorylation. Figure 1A shows that depletion of AURKA reduced PLK1Thr210 phosphorylation without affecting the abundance of total PLK1, confirming that the presence of AURKA was important for PLK1 activation during mitosis. In contrast, depletion of AURKB did not significantly affect PLK1 activity. The immunoblotting analysis also confirmed the efficient depletion of AURKA and AURKB by the siRNAs.


Co-inhibition of polo-like kinase 1 and Aurora kinases promotes mitotic catastrophe.

Li J, Hong MJ, Chow JP, Man WY, Mak JP, Ma HT, Poon RY - Oncotarget (2015)

Loss of Aurora kinases disrupts PLK1 activity during mitosis(A) Depletion of AURKA impairs the activation of PLK1. HeLa cells were transfected with control siRNA, siAURKA, or siAURKB. The cells were enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting. CDC27 analysis was included as a marker of mitosis. The positions of the unphosphorylated and mitotic form of CDC27 are indicated. Uniform loading of lysates was confirmed by immunoblotting for actin. (B) Depletion of PLK1 does not affect the activation of AURKA or AURKB. HeLa cells were transfected with control siRNA or siPLK1, before enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496220&req=5

Figure 1: Loss of Aurora kinases disrupts PLK1 activity during mitosis(A) Depletion of AURKA impairs the activation of PLK1. HeLa cells were transfected with control siRNA, siAURKA, or siAURKB. The cells were enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting. CDC27 analysis was included as a marker of mitosis. The positions of the unphosphorylated and mitotic form of CDC27 are indicated. Uniform loading of lysates was confirmed by immunoblotting for actin. (B) Depletion of PLK1 does not affect the activation of AURKA or AURKB. HeLa cells were transfected with control siRNA or siPLK1, before enriched in G2 phase or mitosis as described in Materials and Methods. Lysates were prepared and the indicated proteins were detected with immunoblotting.
Mentions: To determine the relationship between Aurora kinases and PLK1 during G2 phase and mitosis, we first downregulated the Aurora kinases using specific siRNAs. After HeLa cells were transfected with siRNAs against AURKA and AURKB (siAURKA and siAURKB respectively), they were synchronized at either G2 phase (using a double thymidine blockÔÇôrelease procedure) or mitosis (using a procedure involving nocodazole followed by mechanical shake-off). Lysates were prepared and the activity of PLK1 was determined through the level of PLK1Thr210 phosphorylation. Figure 1A shows that depletion of AURKA reduced PLK1Thr210 phosphorylation without affecting the abundance of total PLK1, confirming that the presence of AURKA was important for PLK1 activation during mitosis. In contrast, depletion of AURKB did not significantly affect PLK1 activity. The immunoblotting analysis also confirmed the efficient depletion of AURKA and AURKB by the siRNAs.

Bottom Line: Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536).We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells.Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Science, Center for Cancer Research, and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.

ABSTRACT
Mitosis is choreographed by a number of protein kinases including polo-like kinases and Aurora kinases. As these kinases are frequently dysregulated in cancers, small-molecule inhibitors have been developed for targeted anticancer therapies. Given that PLK1 and Aurora kinases possess both unique functions as well as co-regulate multiple mitotic events, whether pharmacological inhibition of these kinases together can enhance mitotic catastrophe remains an outstanding issue to be determined. Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536). We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells. Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells. These observations underscore the mechanism and potential benefits of targeting PLK1 and Aurora kinases to induce mitotic catastrophe in cancer cells.

No MeSH data available.


Related in: MedlinePlus