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Class I histone deacetylase inhibitors inhibit the retention of BRCA1 and 53BP1 at the site of DNA damage.

Fukuda T, Wu W, Okada M, Maeda I, Kojima Y, Hayami R, Miyoshi Y, Tsugawa K, Ohta T - Cancer Sci. (2015)

Bottom Line: Reflecting their effects on histone modifications, the HDAC inhibitors inhibit ionizing radiation-induced foci (IRIF) formation of BRCA1 and BARD1 as well as 53BP1 and RIF1, whereas UNC0638 suppresses IRIF formation of BRCA1 and BARD1 but not 53BP1 and RIF1.Although HDAC inhibitors suppressed HDR, they did not cooperate with the poly(ADP-ribose) polymerase inhibitor olaparib to block cancer cell growth, possibly due to simultaneous suppression of NHEJ pathway components.Collectively, these results suggest the mechanism by that HDAC inhibitors inhibit both the HDR and NHEJ pathways, whereas HKMT inhibitor inhibits only the HDR pathway; this finding may affect the chemosensitizing effects of the inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Translational Oncology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan.

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Histone deacetylase (HDAC) and HKMT inhibitors suppress homology-directed repair (HDR). (a) Fluorescence-activated cell sorting (FACS) data on HDR of I-SceI-induced DSB in HeLa DR-GFP reporter cells treated with DMSO, MS-275, FK228 or UNC0638. (b) Quantification of the GFP-positive fraction. Averages ± SD normalized to cells with DMSO were derived from two independent experiments. Significant differences were calculated compared to DMSO-treated cells: *P = 0.002, **P < 0.001. (c) U2OS cells treated with DMSO, MS-275, FK228 or UNC0638 were exposed to infrared (IR) and immunostained with γH2AX and RAD51 6 h after IR. Quantification of the cells displaying more than 20 RAD51 foci. Error bars represent SD from two independent experiments, each based on more than 100 cells. Significant differences were calculated compared to DMSO-treated cells: *P = 0.006, **P = 0.012, ***P = 0.003.
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fig05: Histone deacetylase (HDAC) and HKMT inhibitors suppress homology-directed repair (HDR). (a) Fluorescence-activated cell sorting (FACS) data on HDR of I-SceI-induced DSB in HeLa DR-GFP reporter cells treated with DMSO, MS-275, FK228 or UNC0638. (b) Quantification of the GFP-positive fraction. Averages ± SD normalized to cells with DMSO were derived from two independent experiments. Significant differences were calculated compared to DMSO-treated cells: *P = 0.002, **P < 0.001. (c) U2OS cells treated with DMSO, MS-275, FK228 or UNC0638 were exposed to infrared (IR) and immunostained with γH2AX and RAD51 6 h after IR. Quantification of the cells displaying more than 20 RAD51 foci. Error bars represent SD from two independent experiments, each based on more than 100 cells. Significant differences were calculated compared to DMSO-treated cells: *P = 0.006, **P = 0.012, ***P = 0.003.

Mentions: To evaluate the effects of HDAC inhibitors and UNC0638 on HDR, we used the gene conversion assay with DR-GFP reporter cells. Treatment with HDAC inhibitors reduced HDR at I-SceI nuclease-induced DSB (Fig.5a,b). The percentages of homologous recombination in cells treated with MS-275 and FK228 relative to that in cells treated with DMSO were 53.7% and 68.8%, respectively (Fig.5b). The effect was modest when compared to UNC0638, which reduced HDR to 38.9% (Fig.5a,b). We also analyzed the IRIF composed of RAD51, the effector of HDR. MS-275, FK228 and UNC0638 all reduced the formation of IRIF of RAD51, although the effect of FK228 was modest at the doses tested. The RAD51-IRIF-positive fractions in cells treated with DMSO, MS-275, FK228 and UNC0638 were 71.4%, 20.7%, 47.0% and 30.6%, respectively (Fig.5c).


Class I histone deacetylase inhibitors inhibit the retention of BRCA1 and 53BP1 at the site of DNA damage.

Fukuda T, Wu W, Okada M, Maeda I, Kojima Y, Hayami R, Miyoshi Y, Tsugawa K, Ohta T - Cancer Sci. (2015)

Histone deacetylase (HDAC) and HKMT inhibitors suppress homology-directed repair (HDR). (a) Fluorescence-activated cell sorting (FACS) data on HDR of I-SceI-induced DSB in HeLa DR-GFP reporter cells treated with DMSO, MS-275, FK228 or UNC0638. (b) Quantification of the GFP-positive fraction. Averages ± SD normalized to cells with DMSO were derived from two independent experiments. Significant differences were calculated compared to DMSO-treated cells: *P = 0.002, **P < 0.001. (c) U2OS cells treated with DMSO, MS-275, FK228 or UNC0638 were exposed to infrared (IR) and immunostained with γH2AX and RAD51 6 h after IR. Quantification of the cells displaying more than 20 RAD51 foci. Error bars represent SD from two independent experiments, each based on more than 100 cells. Significant differences were calculated compared to DMSO-treated cells: *P = 0.006, **P = 0.012, ***P = 0.003.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4556395&req=5

fig05: Histone deacetylase (HDAC) and HKMT inhibitors suppress homology-directed repair (HDR). (a) Fluorescence-activated cell sorting (FACS) data on HDR of I-SceI-induced DSB in HeLa DR-GFP reporter cells treated with DMSO, MS-275, FK228 or UNC0638. (b) Quantification of the GFP-positive fraction. Averages ± SD normalized to cells with DMSO were derived from two independent experiments. Significant differences were calculated compared to DMSO-treated cells: *P = 0.002, **P < 0.001. (c) U2OS cells treated with DMSO, MS-275, FK228 or UNC0638 were exposed to infrared (IR) and immunostained with γH2AX and RAD51 6 h after IR. Quantification of the cells displaying more than 20 RAD51 foci. Error bars represent SD from two independent experiments, each based on more than 100 cells. Significant differences were calculated compared to DMSO-treated cells: *P = 0.006, **P = 0.012, ***P = 0.003.
Mentions: To evaluate the effects of HDAC inhibitors and UNC0638 on HDR, we used the gene conversion assay with DR-GFP reporter cells. Treatment with HDAC inhibitors reduced HDR at I-SceI nuclease-induced DSB (Fig.5a,b). The percentages of homologous recombination in cells treated with MS-275 and FK228 relative to that in cells treated with DMSO were 53.7% and 68.8%, respectively (Fig.5b). The effect was modest when compared to UNC0638, which reduced HDR to 38.9% (Fig.5a,b). We also analyzed the IRIF composed of RAD51, the effector of HDR. MS-275, FK228 and UNC0638 all reduced the formation of IRIF of RAD51, although the effect of FK228 was modest at the doses tested. The RAD51-IRIF-positive fractions in cells treated with DMSO, MS-275, FK228 and UNC0638 were 71.4%, 20.7%, 47.0% and 30.6%, respectively (Fig.5c).

Bottom Line: Reflecting their effects on histone modifications, the HDAC inhibitors inhibit ionizing radiation-induced foci (IRIF) formation of BRCA1 and BARD1 as well as 53BP1 and RIF1, whereas UNC0638 suppresses IRIF formation of BRCA1 and BARD1 but not 53BP1 and RIF1.Although HDAC inhibitors suppressed HDR, they did not cooperate with the poly(ADP-ribose) polymerase inhibitor olaparib to block cancer cell growth, possibly due to simultaneous suppression of NHEJ pathway components.Collectively, these results suggest the mechanism by that HDAC inhibitors inhibit both the HDR and NHEJ pathways, whereas HKMT inhibitor inhibits only the HDR pathway; this finding may affect the chemosensitizing effects of the inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Translational Oncology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan.

Show MeSH
Related in: MedlinePlus