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Induction of p53-inducible microRNA miR-34 by gamma radiation and bleomycin are different.

Mert U, Ozgür E, Tiryakioglu D, Dalay N, Gezer U - Front Genet (2012)

Bottom Line: The basal level of p53 in MCF-7 cells was higher (approx. 6-fold) than in HeLa cells, and its accumulation was similar for both DNA-damaging agents in both cell lines.BLM did not significantly affect miR-34 expression in both cell types.In conclusion, our findings reveal that miR-34 induction by genotoxic stress may be cell-type specific.

View Article: PubMed Central - PubMed

Affiliation: Department of Basic Oncology, Oncology Institute, Istanbul University Istanbul, Turkey.

ABSTRACT
microRNAs (miRNAs) are small molecules in their mature form and master regulators of gene expression. Recent work has shown that miRNAs are involved in the p53 network. Of the various miRNAs, miR-34 is regulated by the p53 protein. miR-34 can be induced by ionizing radiation (IR) in vitro and in vivo. However, there is no data in the literature for induction of miR-34 by a chemical agent inducing DNA damage. Here we studied the expression of miR-34 in HeLa and MCF-7 cells exposed to genotoxic stress-induced by bleomycin (BLM) or γ-radiation. We first analyzed p53 accumulation upon DNA damage induction. The basal level of p53 in MCF-7 cells was higher (approx. 6-fold) than in HeLa cells, and its accumulation was similar for both DNA-damaging agents in both cell lines. We have shown that miR-34 is significantly induced by γ-radiation in HeLa cells, but not in MCF-7 cells. BLM did not significantly affect miR-34 expression in both cell types. In conclusion, our findings reveal that miR-34 induction by genotoxic stress may be cell-type specific.

No MeSH data available.


Related in: MedlinePlus

miR-34 expression in HeLa and MCF-7 cells. miR-34 levels were measured by quantitative PCR in HeLa (A) and MCF-7 (B) cells exposed to genotoxic stress. Results of three-independent cell culture experiments were evaluated to calculate the average value of relative gene expression. Each column represents mean + S.E.
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Figure 2: miR-34 expression in HeLa and MCF-7 cells. miR-34 levels were measured by quantitative PCR in HeLa (A) and MCF-7 (B) cells exposed to genotoxic stress. Results of three-independent cell culture experiments were evaluated to calculate the average value of relative gene expression. Each column represents mean + S.E.

Mentions: Subsequently, we investigated the expression of miR-34 at the same time point as above. Interestingly, miR-34 was significantly induced only by radiation in HeLa cells (Figure 2A) but not in MCF-7 cells (Figure 2B). BLM-induced DNA damage did not result in an increase of miR-34 levels in both cell lines. In irradiated HeLa cells miR-34 levels were elevated approx. 2 and 14-fold following radiation at doses of 2 and 5 Gy, respectively (p < 0.01). In contrast to miR-34, levels of miR-195 were not affected by genotoxic stress (data not shown) indicating the specificity of the induction.


Induction of p53-inducible microRNA miR-34 by gamma radiation and bleomycin are different.

Mert U, Ozgür E, Tiryakioglu D, Dalay N, Gezer U - Front Genet (2012)

miR-34 expression in HeLa and MCF-7 cells. miR-34 levels were measured by quantitative PCR in HeLa (A) and MCF-7 (B) cells exposed to genotoxic stress. Results of three-independent cell culture experiments were evaluated to calculate the average value of relative gene expression. Each column represents mean + S.E.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475997&req=5

Figure 2: miR-34 expression in HeLa and MCF-7 cells. miR-34 levels were measured by quantitative PCR in HeLa (A) and MCF-7 (B) cells exposed to genotoxic stress. Results of three-independent cell culture experiments were evaluated to calculate the average value of relative gene expression. Each column represents mean + S.E.
Mentions: Subsequently, we investigated the expression of miR-34 at the same time point as above. Interestingly, miR-34 was significantly induced only by radiation in HeLa cells (Figure 2A) but not in MCF-7 cells (Figure 2B). BLM-induced DNA damage did not result in an increase of miR-34 levels in both cell lines. In irradiated HeLa cells miR-34 levels were elevated approx. 2 and 14-fold following radiation at doses of 2 and 5 Gy, respectively (p < 0.01). In contrast to miR-34, levels of miR-195 were not affected by genotoxic stress (data not shown) indicating the specificity of the induction.

Bottom Line: The basal level of p53 in MCF-7 cells was higher (approx. 6-fold) than in HeLa cells, and its accumulation was similar for both DNA-damaging agents in both cell lines.BLM did not significantly affect miR-34 expression in both cell types.In conclusion, our findings reveal that miR-34 induction by genotoxic stress may be cell-type specific.

View Article: PubMed Central - PubMed

Affiliation: Department of Basic Oncology, Oncology Institute, Istanbul University Istanbul, Turkey.

ABSTRACT
microRNAs (miRNAs) are small molecules in their mature form and master regulators of gene expression. Recent work has shown that miRNAs are involved in the p53 network. Of the various miRNAs, miR-34 is regulated by the p53 protein. miR-34 can be induced by ionizing radiation (IR) in vitro and in vivo. However, there is no data in the literature for induction of miR-34 by a chemical agent inducing DNA damage. Here we studied the expression of miR-34 in HeLa and MCF-7 cells exposed to genotoxic stress-induced by bleomycin (BLM) or γ-radiation. We first analyzed p53 accumulation upon DNA damage induction. The basal level of p53 in MCF-7 cells was higher (approx. 6-fold) than in HeLa cells, and its accumulation was similar for both DNA-damaging agents in both cell lines. We have shown that miR-34 is significantly induced by γ-radiation in HeLa cells, but not in MCF-7 cells. BLM did not significantly affect miR-34 expression in both cell types. In conclusion, our findings reveal that miR-34 induction by genotoxic stress may be cell-type specific.

No MeSH data available.


Related in: MedlinePlus