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The Effect of MicroRNA-124 Overexpression on Anti-Tumor Drug Sensitivity.

Chen SM, Chou WC, Hu LY, Hsiung CN, Chu HW, Huang YL, Hsu HM, Yu JC, Shen CY - PLoS ONE (2015)

Bottom Line: In the present study, we found that overexpression of miR-124 was associated with reduced DNA repair capacity in cultured cancer cells and increased sensitivity of cells to DNA-damaging anti-tumor drugs, specifically those that cause the formation of DNA strand-breaks (SBs).The translational relevance of this role of miR-124 in anti-tumor drug sensitivity is suggested by the finding that increased miR-124 expression correlates with better breast cancer prognosis, specifically in patients receiving chemotherapy.These findings suggest that miR-124 could potentially be used as a therapeutic agent to improve the efficacy of chemotherapy with DNA-damaging agents.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.

ABSTRACT
MicroRNAs play critical roles in regulating various physiological processes, including growth and development. Previous studies have shown that microRNA-124 (miR-124) participates not only in regulation of early neurogenesis but also in suppression of tumorigenesis. In the present study, we found that overexpression of miR-124 was associated with reduced DNA repair capacity in cultured cancer cells and increased sensitivity of cells to DNA-damaging anti-tumor drugs, specifically those that cause the formation of DNA strand-breaks (SBs). We then examined which DNA repair-related genes, particularly the genes of SB repair, were regulated by miR-124. Two SB repair-related genes, encoding ATM interactor (ATMIN) and poly (ADP-ribose) polymerase 1 (PARP1), were strongly affected by miR-124 overexpression, by binding of miR-124 to the 3¢-untranslated region of their mRNAs. As a result, the capacity of cells to repair DNA SBs, such as those resulting from homologous recombination, was significantly reduced upon miR-124 overexpression. A particularly important therapeutic implication of this finding is that overexpression of miR-124 enhanced cell sensitivity to multiple DNA-damaging agents via ATMIN- and PARP1-mediated mechanisms. The translational relevance of this role of miR-124 in anti-tumor drug sensitivity is suggested by the finding that increased miR-124 expression correlates with better breast cancer prognosis, specifically in patients receiving chemotherapy. These findings suggest that miR-124 could potentially be used as a therapeutic agent to improve the efficacy of chemotherapy with DNA-damaging agents.

No MeSH data available.


Related in: MedlinePlus

Introduction of ATMIN and PARP1 reverses the DNA repair defect induced by miR-124 overexpression.(A) HR repair capacity in cells transfected with the indicated combinations of vector control (VC) or the constructs overexpressing miR-124, ATMIN, or PARP1. *Significantly different (P < 0.05) from VC. #Significantly different (P < 0.05) from the miR-124-overexpressing group. (B) Comet assay to detect DNA SBs in cells overexpressing VC, miR-124, miR-124 + ATMIN, or miR-124 + PARP1 after treatment with CPT. (C) Effects of ATMIN and PARP1 overexpression on miR-124 overexpression–enhanced sensitivity to CPT (left panel) or ETO (right panel). *Significantly different (P < 0.05) from VC.
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pone.0128472.g005: Introduction of ATMIN and PARP1 reverses the DNA repair defect induced by miR-124 overexpression.(A) HR repair capacity in cells transfected with the indicated combinations of vector control (VC) or the constructs overexpressing miR-124, ATMIN, or PARP1. *Significantly different (P < 0.05) from VC. #Significantly different (P < 0.05) from the miR-124-overexpressing group. (B) Comet assay to detect DNA SBs in cells overexpressing VC, miR-124, miR-124 + ATMIN, or miR-124 + PARP1 after treatment with CPT. (C) Effects of ATMIN and PARP1 overexpression on miR-124 overexpression–enhanced sensitivity to CPT (left panel) or ETO (right panel). *Significantly different (P < 0.05) from VC.

Mentions: To further explore whether miR-124 exerts its effects on DNA repair by downregulating the levels of mRNAs encoding ATMIN and PARP1, we restored ATMIN and PARP1 levels in a cell line stably expressing miR-124 and assessed the DNA repair capacity. In the HR assay, transient transfection with the ATMIN expression vector significantly increased DNA repair capacity in the miR-124-overexpressing cells to the level of the vector control. Restoration of PARP1 only slightly increased repair capacity compared with the miR-124-overexpressing group (Fig 5A and S4 Fig). This may be partially explained by that, as compared to ATMIN, PARP1 plays a relatively minor role of homologous recombination, which is the parameter measured in this HR assay. However, in the comet assay, restoration of PARP1 as well as ATMIN in miR-124-overexpressing cells decreased residual DNA damage after CPT treatment (Fig 5B). Next, we investigated whether restoration of ATMIN and PARP1 affected cell survival 5 days after CPT treatment. We found that increasing ATMIN or PARP1 equally increased cell survival in the miR-124-overexpressing groups. Similar increases in cell survival were seen when the levels of ATMIN and PARP1 were restored in miR-124-overexpressing ETO-treated cells (Fig 5C).


The Effect of MicroRNA-124 Overexpression on Anti-Tumor Drug Sensitivity.

Chen SM, Chou WC, Hu LY, Hsiung CN, Chu HW, Huang YL, Hsu HM, Yu JC, Shen CY - PLoS ONE (2015)

Introduction of ATMIN and PARP1 reverses the DNA repair defect induced by miR-124 overexpression.(A) HR repair capacity in cells transfected with the indicated combinations of vector control (VC) or the constructs overexpressing miR-124, ATMIN, or PARP1. *Significantly different (P < 0.05) from VC. #Significantly different (P < 0.05) from the miR-124-overexpressing group. (B) Comet assay to detect DNA SBs in cells overexpressing VC, miR-124, miR-124 + ATMIN, or miR-124 + PARP1 after treatment with CPT. (C) Effects of ATMIN and PARP1 overexpression on miR-124 overexpression–enhanced sensitivity to CPT (left panel) or ETO (right panel). *Significantly different (P < 0.05) from VC.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4482746&req=5

pone.0128472.g005: Introduction of ATMIN and PARP1 reverses the DNA repair defect induced by miR-124 overexpression.(A) HR repair capacity in cells transfected with the indicated combinations of vector control (VC) or the constructs overexpressing miR-124, ATMIN, or PARP1. *Significantly different (P < 0.05) from VC. #Significantly different (P < 0.05) from the miR-124-overexpressing group. (B) Comet assay to detect DNA SBs in cells overexpressing VC, miR-124, miR-124 + ATMIN, or miR-124 + PARP1 after treatment with CPT. (C) Effects of ATMIN and PARP1 overexpression on miR-124 overexpression–enhanced sensitivity to CPT (left panel) or ETO (right panel). *Significantly different (P < 0.05) from VC.
Mentions: To further explore whether miR-124 exerts its effects on DNA repair by downregulating the levels of mRNAs encoding ATMIN and PARP1, we restored ATMIN and PARP1 levels in a cell line stably expressing miR-124 and assessed the DNA repair capacity. In the HR assay, transient transfection with the ATMIN expression vector significantly increased DNA repair capacity in the miR-124-overexpressing cells to the level of the vector control. Restoration of PARP1 only slightly increased repair capacity compared with the miR-124-overexpressing group (Fig 5A and S4 Fig). This may be partially explained by that, as compared to ATMIN, PARP1 plays a relatively minor role of homologous recombination, which is the parameter measured in this HR assay. However, in the comet assay, restoration of PARP1 as well as ATMIN in miR-124-overexpressing cells decreased residual DNA damage after CPT treatment (Fig 5B). Next, we investigated whether restoration of ATMIN and PARP1 affected cell survival 5 days after CPT treatment. We found that increasing ATMIN or PARP1 equally increased cell survival in the miR-124-overexpressing groups. Similar increases in cell survival were seen when the levels of ATMIN and PARP1 were restored in miR-124-overexpressing ETO-treated cells (Fig 5C).

Bottom Line: In the present study, we found that overexpression of miR-124 was associated with reduced DNA repair capacity in cultured cancer cells and increased sensitivity of cells to DNA-damaging anti-tumor drugs, specifically those that cause the formation of DNA strand-breaks (SBs).The translational relevance of this role of miR-124 in anti-tumor drug sensitivity is suggested by the finding that increased miR-124 expression correlates with better breast cancer prognosis, specifically in patients receiving chemotherapy.These findings suggest that miR-124 could potentially be used as a therapeutic agent to improve the efficacy of chemotherapy with DNA-damaging agents.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.

ABSTRACT
MicroRNAs play critical roles in regulating various physiological processes, including growth and development. Previous studies have shown that microRNA-124 (miR-124) participates not only in regulation of early neurogenesis but also in suppression of tumorigenesis. In the present study, we found that overexpression of miR-124 was associated with reduced DNA repair capacity in cultured cancer cells and increased sensitivity of cells to DNA-damaging anti-tumor drugs, specifically those that cause the formation of DNA strand-breaks (SBs). We then examined which DNA repair-related genes, particularly the genes of SB repair, were regulated by miR-124. Two SB repair-related genes, encoding ATM interactor (ATMIN) and poly (ADP-ribose) polymerase 1 (PARP1), were strongly affected by miR-124 overexpression, by binding of miR-124 to the 3¢-untranslated region of their mRNAs. As a result, the capacity of cells to repair DNA SBs, such as those resulting from homologous recombination, was significantly reduced upon miR-124 overexpression. A particularly important therapeutic implication of this finding is that overexpression of miR-124 enhanced cell sensitivity to multiple DNA-damaging agents via ATMIN- and PARP1-mediated mechanisms. The translational relevance of this role of miR-124 in anti-tumor drug sensitivity is suggested by the finding that increased miR-124 expression correlates with better breast cancer prognosis, specifically in patients receiving chemotherapy. These findings suggest that miR-124 could potentially be used as a therapeutic agent to improve the efficacy of chemotherapy with DNA-damaging agents.

No MeSH data available.


Related in: MedlinePlus