Page 118 - 2014 Printable Abstract Book
P. 118
(PS1-27) Heat shock factor 1 induces defective repair activity and aneuploidy by interfering the
2
1
1
interaction between ku86 and ku70. Ga-Young Kang ; Eun-Ho Kim, Doctor ; and Yun-sil Lee, Professor
1
Ewha Womans University, Seoul, Korea, Republic of and Korea Institute of Radiological and Medical
Sciences, Seoul, Korea, Republic of
2
Previous our reports suggest that, heat shock factor1 (HSF1) phosphorylation by Plk1 has been
involved in mitotic regulation and p53 function dependently with its transcriptional activity (Cancer Res,
2009). In this study, we further demonstrated the non-transcriptional functions of HSF1 in DNA damage
responses. HSF1 directly bound to Ku86 not to Ku70. Both N-terminal motif of HSF1 and Ku86 were the
interaction partners. When the small-interfering RNAs (siRNA) of HSF1 was treated to the cells, the levels
of p-DNA-PKcs and γ-H2AX by ionizing radiation (IR) were potentiated and repair activity was increased
when double strand break (DSB) pull down assay was performed .These phenomena were also found in
HSF1 knock out MEF cells. However, when HSF1 was overexpressed, opposite effects were observed,
which was similar to those of Ku80 knock out cells. Moreover, a higher level of aneuploidy by IR was found
in HSF1 overexpressed cells and knock down of HSF1 showed vice versa. From the data, it was suggested
that HSF1 with interaction of Ku86 induced not only genomic instability but also defective DNA damage
responses by DNA damage such as IR.
(PS1-28) Novel, non-targeted effect of HZE particle radiation on the DNA double strand break repair
2
1
1
1
1
machinery. Zhentian Li ; Xuang Zheng ; Ya Wang ; and William S. Dynan, Emory University, Atlanta, GA
and Wuhan University, Wuhan, China
2
48
56
Prior work has shown that Fe and Ti particle irradiation of human cells negatively affects the
DNA double-strand break repair machinery. Cells with a history of HZE exposure are up to three times
more likely to misrepair new double strand breaks created by the rare-cutting nuclease I-SceI. Mutagenic
outcomes include translocations between I-SceI breaks on different chromosomes and deletion of an
intervening sequence between I-SceI breaks on the same chromosome. We interpret the results in terms
of inhibition of classical nonhomologous end joining and reliance on alternative, more mutagenic repair
pathways. We show here that this is, in part, a nontargeted effect that is transmissible from irradiated
56
cells to non-irradiated bystanders. In these experiments, cells were irradiated with 600 MeV/u Fe or
48
1000 MeV/u Ti ions at doses of 0.3 Gy and 1.0 Gy, or with 320 kV X-rays at doses of 0.3 Gy, 1.0 Gy or 3.0
Gy. After 1, 7, 14, or 21 days of recovery, they were co-cultured with naïve reporter cells. When the
bystanders were challenged with I-SceI, they showed an increase in enzymatically-induced translocations
of 2-4 fold, and a smaller but significant increase in enzymatically-induced deletions. The effect was seen
when HZE-exposed cells were co-cultured with bystanders at 7 days post-irradiation, but not at earlier or
later time points. It was seen only with HZE particles and not X-rays. To understand the mechanism of this
non-targeted effect, we performed genome wide expression profiling on directly irradiated cells that were
56
harvested 7 days post Fe exposure. The most highly induced genes encoded secreted products related
to cellular senescence or pro-inflammatory responses. Results suggest that a paracrine mechanism,
mediated by secreted factors, instructs bystander cells to increase their reliance on an error-prone repair
pathway. Results define a novel, non-targeted effect of HZE particle radiation that may amplify cancer
risk, particularly at low fluences where only a small fraction of cells are directly hit.
116 | P a g e
2
1
1
interaction between ku86 and ku70. Ga-Young Kang ; Eun-Ho Kim, Doctor ; and Yun-sil Lee, Professor
1
Ewha Womans University, Seoul, Korea, Republic of and Korea Institute of Radiological and Medical
Sciences, Seoul, Korea, Republic of
2
Previous our reports suggest that, heat shock factor1 (HSF1) phosphorylation by Plk1 has been
involved in mitotic regulation and p53 function dependently with its transcriptional activity (Cancer Res,
2009). In this study, we further demonstrated the non-transcriptional functions of HSF1 in DNA damage
responses. HSF1 directly bound to Ku86 not to Ku70. Both N-terminal motif of HSF1 and Ku86 were the
interaction partners. When the small-interfering RNAs (siRNA) of HSF1 was treated to the cells, the levels
of p-DNA-PKcs and γ-H2AX by ionizing radiation (IR) were potentiated and repair activity was increased
when double strand break (DSB) pull down assay was performed .These phenomena were also found in
HSF1 knock out MEF cells. However, when HSF1 was overexpressed, opposite effects were observed,
which was similar to those of Ku80 knock out cells. Moreover, a higher level of aneuploidy by IR was found
in HSF1 overexpressed cells and knock down of HSF1 showed vice versa. From the data, it was suggested
that HSF1 with interaction of Ku86 induced not only genomic instability but also defective DNA damage
responses by DNA damage such as IR.
(PS1-28) Novel, non-targeted effect of HZE particle radiation on the DNA double strand break repair
2
1
1
1
1
machinery. Zhentian Li ; Xuang Zheng ; Ya Wang ; and William S. Dynan, Emory University, Atlanta, GA
and Wuhan University, Wuhan, China
2
48
56
Prior work has shown that Fe and Ti particle irradiation of human cells negatively affects the
DNA double-strand break repair machinery. Cells with a history of HZE exposure are up to three times
more likely to misrepair new double strand breaks created by the rare-cutting nuclease I-SceI. Mutagenic
outcomes include translocations between I-SceI breaks on different chromosomes and deletion of an
intervening sequence between I-SceI breaks on the same chromosome. We interpret the results in terms
of inhibition of classical nonhomologous end joining and reliance on alternative, more mutagenic repair
pathways. We show here that this is, in part, a nontargeted effect that is transmissible from irradiated
56
cells to non-irradiated bystanders. In these experiments, cells were irradiated with 600 MeV/u Fe or
48
1000 MeV/u Ti ions at doses of 0.3 Gy and 1.0 Gy, or with 320 kV X-rays at doses of 0.3 Gy, 1.0 Gy or 3.0
Gy. After 1, 7, 14, or 21 days of recovery, they were co-cultured with naïve reporter cells. When the
bystanders were challenged with I-SceI, they showed an increase in enzymatically-induced translocations
of 2-4 fold, and a smaller but significant increase in enzymatically-induced deletions. The effect was seen
when HZE-exposed cells were co-cultured with bystanders at 7 days post-irradiation, but not at earlier or
later time points. It was seen only with HZE particles and not X-rays. To understand the mechanism of this
non-targeted effect, we performed genome wide expression profiling on directly irradiated cells that were
56
harvested 7 days post Fe exposure. The most highly induced genes encoded secreted products related
to cellular senescence or pro-inflammatory responses. Results suggest that a paracrine mechanism,
mediated by secreted factors, instructs bystander cells to increase their reliance on an error-prone repair
pathway. Results define a novel, non-targeted effect of HZE particle radiation that may amplify cancer
risk, particularly at low fluences where only a small fraction of cells are directly hit.
116 | P a g e
