Limits...
Expression of miR-34c induces G2/M cell cycle arrest in breast cancer cells.

Achari C, Winslow S, Ceder Y, Larsson C - BMC Cancer (2014)

Bottom Line: Additionally, miR-34c influenced the cell cycle mainly by inducing an arrest in the G2/M phase.We found that expression levels of the known cell cycle-regulating miR-34 targets CCND1, CDK4 and CDK6, were downregulated upon miR-34c expression in breast cancer cell lines.In addition, the levels of CDC23, an important mediator in mitotic progression, were suppressed following miR-34c expression, and siRNAs targeting CDC23 mimicked the effect of miR-34c on G2/M arrest.

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Translational Cancer Research, Lund University, Medicon Village, Building 404:C3, 223 81 Lund, Sweden. Christer.Larsson@med.lu.se.

ABSTRACT

Background: MicroRNA-34 is a family of three miRNAs that have been reported to function as tumor suppressor miRNAs and show decreased expression in various cancers. Here, we examine functions of miR-34c in basal-like breast cancer cells.

Methods: Data from The Cancer Genome Atlas (TCGA) were used for evaluation of expression in primary breast cancers. Cellular processes affected by miR-34c were investigated by thymidine incorporation, Annexin V-assays and cell cycle analysis using breast cancer cell lines. Effects on potential targets were analyzed with qPCR and Western blot.

Results: TCGA data revealed that miR-34c was expressed at lower levels in basal-like breast cancer tumors and low expression was associated with poor prognosis. Ectopic expression of miR-34c in basal-like breast cancer cell lines resulted in suppressed proliferation and increased cell death. Additionally, miR-34c influenced the cell cycle mainly by inducing an arrest in the G2/M phase. We found that expression levels of the known cell cycle-regulating miR-34 targets CCND1, CDK4 and CDK6, were downregulated upon miR-34c expression in breast cancer cell lines. In addition, the levels of CDC23, an important mediator in mitotic progression, were suppressed following miR-34c expression, and siRNAs targeting CDC23 mimicked the effect of miR-34c on G2/M arrest. However, protein levels of PRKCA, a predicted miR-34c target and a known regulator of breast cancer cell proliferation were not influenced by miR-34c.

Conclusions: Together, our results support the role of miR-34c as a tumor suppressor miRNA also in breast cancer.

Show MeSH

Related in: MedlinePlus

Effects ofCDC23down regulation on cell cycle distribution. MDA-MB-231 cells were treated for 72 h with three separate siRNAs targeting CDC23. Thereafter the cell cycle distribution was analyzed with flow cytometry (A) and CDC23 protein levels were analyzed with Western blot (B). The data in A are mean ± SEM from three separate experiments. Asterisks indicate statistically significant differences (* p < 0.05, *** p < 0.001, paired t-test) compared to control cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4125691&req=5

Fig6: Effects ofCDC23down regulation on cell cycle distribution. MDA-MB-231 cells were treated for 72 h with three separate siRNAs targeting CDC23. Thereafter the cell cycle distribution was analyzed with flow cytometry (A) and CDC23 protein levels were analyzed with Western blot (B). The data in A are mean ± SEM from three separate experiments. Asterisks indicate statistically significant differences (* p < 0.05, *** p < 0.001, paired t-test) compared to control cells.

Mentions: To analyse whether suppression of CDC23 levels is sufficient to elicit some miR-34c effects, MDA-MB-231 cells were treated with siRNA targeting CDC23 mRNA (Figure 6). This resulted in fewer cells in the G1 and increases in the G2/M phase. However, no effect on cells in the sub-G1 phase could be seen.Figure 6


Expression of miR-34c induces G2/M cell cycle arrest in breast cancer cells.

Achari C, Winslow S, Ceder Y, Larsson C - BMC Cancer (2014)

Effects ofCDC23down regulation on cell cycle distribution. MDA-MB-231 cells were treated for 72 h with three separate siRNAs targeting CDC23. Thereafter the cell cycle distribution was analyzed with flow cytometry (A) and CDC23 protein levels were analyzed with Western blot (B). The data in A are mean ± SEM from three separate experiments. Asterisks indicate statistically significant differences (* p < 0.05, *** p < 0.001, paired t-test) compared to control cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4125691&req=5

Fig6: Effects ofCDC23down regulation on cell cycle distribution. MDA-MB-231 cells were treated for 72 h with three separate siRNAs targeting CDC23. Thereafter the cell cycle distribution was analyzed with flow cytometry (A) and CDC23 protein levels were analyzed with Western blot (B). The data in A are mean ± SEM from three separate experiments. Asterisks indicate statistically significant differences (* p < 0.05, *** p < 0.001, paired t-test) compared to control cells.
Mentions: To analyse whether suppression of CDC23 levels is sufficient to elicit some miR-34c effects, MDA-MB-231 cells were treated with siRNA targeting CDC23 mRNA (Figure 6). This resulted in fewer cells in the G1 and increases in the G2/M phase. However, no effect on cells in the sub-G1 phase could be seen.Figure 6

Bottom Line: Additionally, miR-34c influenced the cell cycle mainly by inducing an arrest in the G2/M phase.We found that expression levels of the known cell cycle-regulating miR-34 targets CCND1, CDK4 and CDK6, were downregulated upon miR-34c expression in breast cancer cell lines.In addition, the levels of CDC23, an important mediator in mitotic progression, were suppressed following miR-34c expression, and siRNAs targeting CDC23 mimicked the effect of miR-34c on G2/M arrest.

View Article: PubMed Central - PubMed

Affiliation: Department of Laboratory Medicine, Translational Cancer Research, Lund University, Medicon Village, Building 404:C3, 223 81 Lund, Sweden. Christer.Larsson@med.lu.se.

ABSTRACT

Background: MicroRNA-34 is a family of three miRNAs that have been reported to function as tumor suppressor miRNAs and show decreased expression in various cancers. Here, we examine functions of miR-34c in basal-like breast cancer cells.

Methods: Data from The Cancer Genome Atlas (TCGA) were used for evaluation of expression in primary breast cancers. Cellular processes affected by miR-34c were investigated by thymidine incorporation, Annexin V-assays and cell cycle analysis using breast cancer cell lines. Effects on potential targets were analyzed with qPCR and Western blot.

Results: TCGA data revealed that miR-34c was expressed at lower levels in basal-like breast cancer tumors and low expression was associated with poor prognosis. Ectopic expression of miR-34c in basal-like breast cancer cell lines resulted in suppressed proliferation and increased cell death. Additionally, miR-34c influenced the cell cycle mainly by inducing an arrest in the G2/M phase. We found that expression levels of the known cell cycle-regulating miR-34 targets CCND1, CDK4 and CDK6, were downregulated upon miR-34c expression in breast cancer cell lines. In addition, the levels of CDC23, an important mediator in mitotic progression, were suppressed following miR-34c expression, and siRNAs targeting CDC23 mimicked the effect of miR-34c on G2/M arrest. However, protein levels of PRKCA, a predicted miR-34c target and a known regulator of breast cancer cell proliferation were not influenced by miR-34c.

Conclusions: Together, our results support the role of miR-34c as a tumor suppressor miRNA also in breast cancer.

Show MeSH
Related in: MedlinePlus