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Isoalantolactone Enhances the Radiosensitivity of UMSCC-10A Cells via Specific Inhibition of Erk1/2 Phosphorylation.

Fan Y, Weng Z, Gao H, Hu J, Wang H, Li L, Liu H - PLoS ONE (2015)

Bottom Line: In this study, the mechanism of action of isoalantolactone as well as its radiosensitizing effect was investigated in UMSCC-10A cells.However, isoalantolactone was significantly reduced radiation-induced the phosphorylation of Erk1/2, whereas it altered the phosphorylation of Mek to a lesser extent.Our results suggested that isoalantolactone enhanced radiation-induced apoptosis, cell cycle arrested and reduced the cell proliferation of UMSCC-10A cells via specifically inhibited the phosphorylation of Erk1/2.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Liaoning Medical University, Jinzhou, Liaoning, China.

ABSTRACT

Background: Although radiotherapy is one of the mainstream approaches for the treatment of head and neck squamous cell carcinoma (HNSCC), this cancer is always associated with resistance to radiation. In this study, the mechanism of action of isoalantolactone as well as its radiosensitizing effect was investigated in UMSCC-10A cells.

Methods: The radiosensitization of UMSCC-10A cells treated with isoalantolactone was analyzed by colony formation assay. The radiosensitization effects of isoalantolactone on cell proliferation, cell cycle and apoptosis regulation were examined by BrdU incorporation assay, DNA content assay and flow cytometry, respectively. Western blotting was performed to determine the effects of isoalantolactone combined with radiation on the protein expression of Mek, extracellular signal-regulated kinase (Erk1/2) as well as phosphorylated Mek and Erk1/2. Erk1/2 knockdown by siRNA was used to confirm that isoalantolactone specifically inhibited the activation of Erk1/2 signaling pathway in UMSCC-10A cells.

Results: Isoalantolactone enhanced the radiosensitivity of UMSCC-10A cells; the sensitivity enhanced ratios (SERs) were 1.44 and 1.63, respectively, for 2.5 and 5 μM. Moreover, isoalantolactone enhanced radiation-induced cell proliferation and apoptosis and cell cycle arrested at G2/M phase. Furthermore, no marked changes were observed in the expression of total Erk1/2 and Mek protein after radiation treatment. However, isoalantolactone was significantly reduced radiation-induced the phosphorylation of Erk1/2, whereas it altered the phosphorylation of Mek to a lesser extent. In addition, the radiosensitivity of UMSCC-10A cells with Erk1/2 knockdown was increased. Isoalantolactone cannot further prevent the proliferation of UMSCC-10A cells with Erk1/2 knockdown which other mechanism regulated cell proliferation.

Conclusion: Our results suggested that isoalantolactone enhanced radiation-induced apoptosis, cell cycle arrested and reduced the cell proliferation of UMSCC-10A cells via specifically inhibited the phosphorylation of Erk1/2. Thus a low concentration of isoalantolactone may be used to overcome the resistance of UMSCC-10A cells to radiation and may be a promising radiosensitizer in cancer therapy.

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Related in: MedlinePlus

Isoalantolactone combined with radiation inhibits the proliferation of UMSCC-10A cells.(A) Representative images from a cell proliferation assay illustrate nuclear staining after the cells were treated with isoalantolactone at 5 μM for 72 hours or radiation at 4 Gy for 4 hours alone or with a combination. (B) The proliferative ability of UMSCC-10A cells was tested with BrdU incorporation assays. The results are representative of three independent experiments. Values represent the mean ± SEM, * P<0.05, **P<0.01compared with the control.
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pone.0145790.g002: Isoalantolactone combined with radiation inhibits the proliferation of UMSCC-10A cells.(A) Representative images from a cell proliferation assay illustrate nuclear staining after the cells were treated with isoalantolactone at 5 μM for 72 hours or radiation at 4 Gy for 4 hours alone or with a combination. (B) The proliferative ability of UMSCC-10A cells was tested with BrdU incorporation assays. The results are representative of three independent experiments. Values represent the mean ± SEM, * P<0.05, **P<0.01compared with the control.

Mentions: To evaluate whether isoalantolactone could enhance the radiation-induced inhibition of cell proliferation, we tested the proliferation of UMSCC-10A cells using a BrdU incorporation assay. As shown in Fig 2A, 5 μM isoalantolactone alone (44.8%) could not inhibit the proliferation of UMSCC-10A cells relative to the untreated cells (46.2%, P>0.05), whereas cells treated with radiation experienced a significant reduction in cell proliferation (28.1%, P<0.05). Compared with radiation or the control group, the proliferation rate of the cells treated with a combination of isoalantolactone and radiation was significantly decreased (11.3%, P< 0.01, Fig 2B).


Isoalantolactone Enhances the Radiosensitivity of UMSCC-10A Cells via Specific Inhibition of Erk1/2 Phosphorylation.

Fan Y, Weng Z, Gao H, Hu J, Wang H, Li L, Liu H - PLoS ONE (2015)

Isoalantolactone combined with radiation inhibits the proliferation of UMSCC-10A cells.(A) Representative images from a cell proliferation assay illustrate nuclear staining after the cells were treated with isoalantolactone at 5 μM for 72 hours or radiation at 4 Gy for 4 hours alone or with a combination. (B) The proliferative ability of UMSCC-10A cells was tested with BrdU incorporation assays. The results are representative of three independent experiments. Values represent the mean ± SEM, * P<0.05, **P<0.01compared with the control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696678&req=5

pone.0145790.g002: Isoalantolactone combined with radiation inhibits the proliferation of UMSCC-10A cells.(A) Representative images from a cell proliferation assay illustrate nuclear staining after the cells were treated with isoalantolactone at 5 μM for 72 hours or radiation at 4 Gy for 4 hours alone or with a combination. (B) The proliferative ability of UMSCC-10A cells was tested with BrdU incorporation assays. The results are representative of three independent experiments. Values represent the mean ± SEM, * P<0.05, **P<0.01compared with the control.
Mentions: To evaluate whether isoalantolactone could enhance the radiation-induced inhibition of cell proliferation, we tested the proliferation of UMSCC-10A cells using a BrdU incorporation assay. As shown in Fig 2A, 5 μM isoalantolactone alone (44.8%) could not inhibit the proliferation of UMSCC-10A cells relative to the untreated cells (46.2%, P>0.05), whereas cells treated with radiation experienced a significant reduction in cell proliferation (28.1%, P<0.05). Compared with radiation or the control group, the proliferation rate of the cells treated with a combination of isoalantolactone and radiation was significantly decreased (11.3%, P< 0.01, Fig 2B).

Bottom Line: In this study, the mechanism of action of isoalantolactone as well as its radiosensitizing effect was investigated in UMSCC-10A cells.However, isoalantolactone was significantly reduced radiation-induced the phosphorylation of Erk1/2, whereas it altered the phosphorylation of Mek to a lesser extent.Our results suggested that isoalantolactone enhanced radiation-induced apoptosis, cell cycle arrested and reduced the cell proliferation of UMSCC-10A cells via specifically inhibited the phosphorylation of Erk1/2.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Liaoning Medical University, Jinzhou, Liaoning, China.

ABSTRACT

Background: Although radiotherapy is one of the mainstream approaches for the treatment of head and neck squamous cell carcinoma (HNSCC), this cancer is always associated with resistance to radiation. In this study, the mechanism of action of isoalantolactone as well as its radiosensitizing effect was investigated in UMSCC-10A cells.

Methods: The radiosensitization of UMSCC-10A cells treated with isoalantolactone was analyzed by colony formation assay. The radiosensitization effects of isoalantolactone on cell proliferation, cell cycle and apoptosis regulation were examined by BrdU incorporation assay, DNA content assay and flow cytometry, respectively. Western blotting was performed to determine the effects of isoalantolactone combined with radiation on the protein expression of Mek, extracellular signal-regulated kinase (Erk1/2) as well as phosphorylated Mek and Erk1/2. Erk1/2 knockdown by siRNA was used to confirm that isoalantolactone specifically inhibited the activation of Erk1/2 signaling pathway in UMSCC-10A cells.

Results: Isoalantolactone enhanced the radiosensitivity of UMSCC-10A cells; the sensitivity enhanced ratios (SERs) were 1.44 and 1.63, respectively, for 2.5 and 5 μM. Moreover, isoalantolactone enhanced radiation-induced cell proliferation and apoptosis and cell cycle arrested at G2/M phase. Furthermore, no marked changes were observed in the expression of total Erk1/2 and Mek protein after radiation treatment. However, isoalantolactone was significantly reduced radiation-induced the phosphorylation of Erk1/2, whereas it altered the phosphorylation of Mek to a lesser extent. In addition, the radiosensitivity of UMSCC-10A cells with Erk1/2 knockdown was increased. Isoalantolactone cannot further prevent the proliferation of UMSCC-10A cells with Erk1/2 knockdown which other mechanism regulated cell proliferation.

Conclusion: Our results suggested that isoalantolactone enhanced radiation-induced apoptosis, cell cycle arrested and reduced the cell proliferation of UMSCC-10A cells via specifically inhibited the phosphorylation of Erk1/2. Thus a low concentration of isoalantolactone may be used to overcome the resistance of UMSCC-10A cells to radiation and may be a promising radiosensitizer in cancer therapy.

Show MeSH
Related in: MedlinePlus