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Breast cancer cell line MCF7 escapes from G1/S arrest induced by proteasome inhibition through a GSK-3β dependent mechanism.

Gavilán E, Giráldez S, Sánchez-Aguayo I, Romero F, Ruano D, Daza P - Sci Rep (2015)

Bottom Line: The study was performed in the breast cancer cell line MCF7 compared to the normal mammary cell line MCF10A.We found that the proteasome inhibitor MG132 induced G1/S arrest in MCF10A, but G2/M arrest in MCF7 cells.The effect of MG132 on MCF7 was reproduced on MCF10A cells in the presence of the glycogen synthase kinase 3β (GSK-3β) inhibitor VII.

View Article: PubMed Central - PubMed

Affiliation: 1] Instituto de Biomedicina de Sevilla (IBIS)-Hospital Universitario Virgen del Rocío, Universidad de Sevilla, Sevilla, Spain [2] Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Sevilla, Sevilla, Spain.

ABSTRACT
Targeting the ubiquitin proteasome pathway has emerged as a rational approach in the treatment of human cancers. Autophagy has been described as a cytoprotective mechanism to increase tumor cell survival under stress conditions. Here, we have focused on the role of proteasome inhibition in cell cycle progression and the role of autophagy in the proliferation recovery. The study was performed in the breast cancer cell line MCF7 compared to the normal mammary cell line MCF10A. We found that the proteasome inhibitor MG132 induced G1/S arrest in MCF10A, but G2/M arrest in MCF7 cells. The effect of MG132 on MCF7 was reproduced on MCF10A cells in the presence of the glycogen synthase kinase 3β (GSK-3β) inhibitor VII. Similarly, MCF7 cells overexpressing constitutively active GSK-3β behaved like MCF10A cells. On the other hand, MCF10A cells remained arrested after MG132 removal while MCF7 recovered the proliferative capacity. Importantly, this recovery was abolished in the presence of the autophagy inhibitor 3-methyladenine (3-MA). Thus, our results support the relevance of GSK-3β and autophagy as two targets for controlling cell cycle progression and proliferative capacity in MCF7, highlighting the co-treatment of breast cancer cells with 3-MA to synergize the effect of the proteasome inhibition.

No MeSH data available.


Related in: MedlinePlus

Analysis of cell recovery following proteasome inhibition. It is shown the proliferative capacity of MCF10A (a) and MCF7 (b) cells during a week after removing MG132 (1 and 5 μM). Data are expressed as average ± SD of cell number. Note MCF7 recovery following 1 μM of MG132, while this is not observed in MCF10A cells.
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f3: Analysis of cell recovery following proteasome inhibition. It is shown the proliferative capacity of MCF10A (a) and MCF7 (b) cells during a week after removing MG132 (1 and 5 μM). Data are expressed as average ± SD of cell number. Note MCF7 recovery following 1 μM of MG132, while this is not observed in MCF10A cells.

Mentions: Based on the different behavior induced by proteasome inhibition in both cell types, we wondered whether molecular and cellular differences could affect the proliferative capability. To address this issue, we analyzed for a week the growing rate of both cell types after removing MG132 (1 and 5 μM). As shown in Fig. 3a,b, control cells were growing properly, while MG132 treatment drastically affected cell proliferation in both cell lines. The higher dose of MG132 caused similar effects on both cell types and neither proliferation nor recovery was observed after a week. However, cellular response to the lower dose of MG132 was quite different in both cell types. While in MCF10A cells, proliferation was very limited (around 10% of control cell number at the end of the assay), the tumor cells started to proliferate 3 to 5 days after MG132 removal, reaching up to the 60% of control cell number at the end of the assay (Fig. 3a,b, respectively). These results indicated that tumor cells escaped from the cell cycle arrest induced by MG132 treatment, while MCF10A did not.


Breast cancer cell line MCF7 escapes from G1/S arrest induced by proteasome inhibition through a GSK-3β dependent mechanism.

Gavilán E, Giráldez S, Sánchez-Aguayo I, Romero F, Ruano D, Daza P - Sci Rep (2015)

Analysis of cell recovery following proteasome inhibition. It is shown the proliferative capacity of MCF10A (a) and MCF7 (b) cells during a week after removing MG132 (1 and 5 μM). Data are expressed as average ± SD of cell number. Note MCF7 recovery following 1 μM of MG132, while this is not observed in MCF10A cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4419540&req=5

f3: Analysis of cell recovery following proteasome inhibition. It is shown the proliferative capacity of MCF10A (a) and MCF7 (b) cells during a week after removing MG132 (1 and 5 μM). Data are expressed as average ± SD of cell number. Note MCF7 recovery following 1 μM of MG132, while this is not observed in MCF10A cells.
Mentions: Based on the different behavior induced by proteasome inhibition in both cell types, we wondered whether molecular and cellular differences could affect the proliferative capability. To address this issue, we analyzed for a week the growing rate of both cell types after removing MG132 (1 and 5 μM). As shown in Fig. 3a,b, control cells were growing properly, while MG132 treatment drastically affected cell proliferation in both cell lines. The higher dose of MG132 caused similar effects on both cell types and neither proliferation nor recovery was observed after a week. However, cellular response to the lower dose of MG132 was quite different in both cell types. While in MCF10A cells, proliferation was very limited (around 10% of control cell number at the end of the assay), the tumor cells started to proliferate 3 to 5 days after MG132 removal, reaching up to the 60% of control cell number at the end of the assay (Fig. 3a,b, respectively). These results indicated that tumor cells escaped from the cell cycle arrest induced by MG132 treatment, while MCF10A did not.

Bottom Line: The study was performed in the breast cancer cell line MCF7 compared to the normal mammary cell line MCF10A.We found that the proteasome inhibitor MG132 induced G1/S arrest in MCF10A, but G2/M arrest in MCF7 cells.The effect of MG132 on MCF7 was reproduced on MCF10A cells in the presence of the glycogen synthase kinase 3β (GSK-3β) inhibitor VII.

View Article: PubMed Central - PubMed

Affiliation: 1] Instituto de Biomedicina de Sevilla (IBIS)-Hospital Universitario Virgen del Rocío, Universidad de Sevilla, Sevilla, Spain [2] Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Sevilla, Sevilla, Spain.

ABSTRACT
Targeting the ubiquitin proteasome pathway has emerged as a rational approach in the treatment of human cancers. Autophagy has been described as a cytoprotective mechanism to increase tumor cell survival under stress conditions. Here, we have focused on the role of proteasome inhibition in cell cycle progression and the role of autophagy in the proliferation recovery. The study was performed in the breast cancer cell line MCF7 compared to the normal mammary cell line MCF10A. We found that the proteasome inhibitor MG132 induced G1/S arrest in MCF10A, but G2/M arrest in MCF7 cells. The effect of MG132 on MCF7 was reproduced on MCF10A cells in the presence of the glycogen synthase kinase 3β (GSK-3β) inhibitor VII. Similarly, MCF7 cells overexpressing constitutively active GSK-3β behaved like MCF10A cells. On the other hand, MCF10A cells remained arrested after MG132 removal while MCF7 recovered the proliferative capacity. Importantly, this recovery was abolished in the presence of the autophagy inhibitor 3-methyladenine (3-MA). Thus, our results support the relevance of GSK-3β and autophagy as two targets for controlling cell cycle progression and proliferative capacity in MCF7, highlighting the co-treatment of breast cancer cells with 3-MA to synergize the effect of the proteasome inhibition.

No MeSH data available.


Related in: MedlinePlus