Page 119 - 2014 Printable Abstract Book
P. 119
(PS1-29) ROS/Autophagy/Nrf2 axis mediated low-dose radiation induced radio-resistance in human
lung adenocarcinoma A549 cell. Ni Chen; Jun Wang; Lijun Wu, PhD, Key Laboratory of Ion Beam
Bioengineering, Chinese Academy of Sciences, Hefei, Anhui, China
Nrf2 is a transcription factor controlling the expression of many types of detoxification enzymes,
including enzymes participating in maintaining cellular oxidative equilibrium. In the present study, the role
of Nrf2 was investigated in the process of low-dose radiation induced radio-resistance. We showed that
5cGy alpha particle induced the radio-resistance of A549 cell, which was shown with increased cell viability
and decreased apoptosis rate, after a challenging dose of 75cGy alpha particle. The expression level of
Nrf2 in whole cell lysate and nucleus fraction of A549 increased after 5cGy radiation, and both the shRNA
of Nrf2 and the chemical inhibitor of Nrf2 target Heme Oxygenase-1(HO-1) suppressed the induced radio-
resistance, indicating the involvement of Nrf2 antioxidant pathway in the process. Furthermore, we found
5cGy alpha particle induced autophagy in A549. Inhibiting autophagy process by chemical inhibitor 3-MA,
the radio-resistance was suppressed, together with the decreased expression of Nrf2 and HO-1. It was
also found that ROS scavenger NAC blocked the autophagy process by 5cGy alpha particle, as well as
expression of Nrf2 and HO-1. And NAC treatment also led to the suppression of the induced radio-
resistance. In conclusion, our study showed that the ROS/Autophagy/Nrf2--HO-1 axis plays important role
in the induction of radio-resistance by low dose radiation.
(PS1-30) Genetic investigation of the function of Nono, a novel double strand break repair factor, in the
2
1
1
1
mouse. Shuyi Li, MD, PhD ; Liliana Souza, Ph. D. ; Zhentian Li, Ph. D. ; Fengjue Shu, Ph. D. ; Erica Silva, Ph.
1
2
3
2
D. ; Hairong Xiong, Ph. D. ; Morgan McLemore ; and William S. Dynan, Ph. D., Department of Radiation
1
Oncology, Emory University School of Medicine, Atlanta, GA ; Department of Hematology, Emory
2
University School of Medicine, Atlanta, GA ; and Institute of Medical Virology, Wuhan University, Wuhan,
China
3
Three genes, SFPQ, NONO, and PSPC1, encode a small family of tandem RRM domain-containing
proteins with diverse functions in RNA processing, transcription, and DNA repair. Our previous work has
shown that an SFPQ•NONO complex promotes a distinct sub-pathway of nonhomologous end joining
(NHEJ) in vitro, implicating it as a novel DNA double-strand break (DSB) repair factor. Consistent with this,
attenuation of NONO function in human fibroblasts leads to partial radiosensitivity, delayed resolution of
DNA repair foci, and an increase in radiation-dependent chromosome aberrations. To investigate the in
vivo function of this complex, we knocked out Nono, the mouse homolog of the human NONO gene. We
hypothesized that a DSB repair deficiency would lead to stem cell exhaustion, sensitivity to DNA damaging
agents, or both. We investigated hematopoietic stem cells, which are known to be sensitive to impairment
of DNA repair. The proportion of stem cells in relation to total bone marrow cells was similar in Nono-
deficient and wild type mice, and bone marrow cell cultures yielded similar numbers and types of colonies.
However, when utilized in a competitive bone marrow transplant, the Nono-deficient hematopoietic cells
had a significant disadvantage, suggestive of sensitivity to endogenous stressors. The testis is another
organ that is frequently affected by DNA repair gene mutations. Testes of Nono-deficient mice show
growth retardation that became apparent between 18 and 26 days of postnatal development. Irradiation
of Nono-deficient mice at 4 Gy led to widespread apoptosis after 24 h, leading to nearly depletion of the
germ cells at 48 h. The co-occurrence of hematopoietic and germ cell defects is reminiscent of other DNA
117 | P a g e
lung adenocarcinoma A549 cell. Ni Chen; Jun Wang; Lijun Wu, PhD, Key Laboratory of Ion Beam
Bioengineering, Chinese Academy of Sciences, Hefei, Anhui, China
Nrf2 is a transcription factor controlling the expression of many types of detoxification enzymes,
including enzymes participating in maintaining cellular oxidative equilibrium. In the present study, the role
of Nrf2 was investigated in the process of low-dose radiation induced radio-resistance. We showed that
5cGy alpha particle induced the radio-resistance of A549 cell, which was shown with increased cell viability
and decreased apoptosis rate, after a challenging dose of 75cGy alpha particle. The expression level of
Nrf2 in whole cell lysate and nucleus fraction of A549 increased after 5cGy radiation, and both the shRNA
of Nrf2 and the chemical inhibitor of Nrf2 target Heme Oxygenase-1(HO-1) suppressed the induced radio-
resistance, indicating the involvement of Nrf2 antioxidant pathway in the process. Furthermore, we found
5cGy alpha particle induced autophagy in A549. Inhibiting autophagy process by chemical inhibitor 3-MA,
the radio-resistance was suppressed, together with the decreased expression of Nrf2 and HO-1. It was
also found that ROS scavenger NAC blocked the autophagy process by 5cGy alpha particle, as well as
expression of Nrf2 and HO-1. And NAC treatment also led to the suppression of the induced radio-
resistance. In conclusion, our study showed that the ROS/Autophagy/Nrf2--HO-1 axis plays important role
in the induction of radio-resistance by low dose radiation.
(PS1-30) Genetic investigation of the function of Nono, a novel double strand break repair factor, in the
2
1
1
1
mouse. Shuyi Li, MD, PhD ; Liliana Souza, Ph. D. ; Zhentian Li, Ph. D. ; Fengjue Shu, Ph. D. ; Erica Silva, Ph.
1
2
3
2
D. ; Hairong Xiong, Ph. D. ; Morgan McLemore ; and William S. Dynan, Ph. D., Department of Radiation
1
Oncology, Emory University School of Medicine, Atlanta, GA ; Department of Hematology, Emory
2
University School of Medicine, Atlanta, GA ; and Institute of Medical Virology, Wuhan University, Wuhan,
China
3
Three genes, SFPQ, NONO, and PSPC1, encode a small family of tandem RRM domain-containing
proteins with diverse functions in RNA processing, transcription, and DNA repair. Our previous work has
shown that an SFPQ•NONO complex promotes a distinct sub-pathway of nonhomologous end joining
(NHEJ) in vitro, implicating it as a novel DNA double-strand break (DSB) repair factor. Consistent with this,
attenuation of NONO function in human fibroblasts leads to partial radiosensitivity, delayed resolution of
DNA repair foci, and an increase in radiation-dependent chromosome aberrations. To investigate the in
vivo function of this complex, we knocked out Nono, the mouse homolog of the human NONO gene. We
hypothesized that a DSB repair deficiency would lead to stem cell exhaustion, sensitivity to DNA damaging
agents, or both. We investigated hematopoietic stem cells, which are known to be sensitive to impairment
of DNA repair. The proportion of stem cells in relation to total bone marrow cells was similar in Nono-
deficient and wild type mice, and bone marrow cell cultures yielded similar numbers and types of colonies.
However, when utilized in a competitive bone marrow transplant, the Nono-deficient hematopoietic cells
had a significant disadvantage, suggestive of sensitivity to endogenous stressors. The testis is another
organ that is frequently affected by DNA repair gene mutations. Testes of Nono-deficient mice show
growth retardation that became apparent between 18 and 26 days of postnatal development. Irradiation
of Nono-deficient mice at 4 Gy led to widespread apoptosis after 24 h, leading to nearly depletion of the
germ cells at 48 h. The co-occurrence of hematopoietic and germ cell defects is reminiscent of other DNA
117 | P a g e
