• Radiation Oncology Journal
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• v.17 no.4
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• pp.299-306
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• 1999

Purpose : The human genetic disorder ataxia-telangiectasia (AT) is a multisystem disease characterized by extreme radiosensitivity. The recent identification of the gene mutated in AT, ATM, and the demonstration that it encodes a homologous domain of phosphatidylinositol 3-kinase (PI3-K), the catalytic subunit of an enzyme involved in transmitting signals from the cell surface to the nucleus, provide support for a role of this gene in signal transduction. Although ionizing radiation was known to induce c-fos transcription, nothing is known about how ATM or PKCI mediated signal transduction pathway modulates the c-fos gene transcription and gene expression. Here we have studied the effect of PKCI on radiation sensitivity and c-fos transcription in normal and AT cells. Materials and Methods: Normal (LM217) and AT (AT5BIVA) cells were transfected with PKCI expression plasmid and the overexpression and integration of PKCI was evaluated by northern blotting and polymerase chain reaction, respectively. 5 Gy of radiation was exposed to LM and AT cells transfected with PKCI expression plasmid and cells were harvested 48 hours after radiation and investigated apoptosis with TUNEL method. The c-fos transcription activity was studied by performing CAT assay of reporter gene after transfection of c-fos CAT plasmid into AT and LM cells. Results: Our results demonstrate for the first time a role of PKCI on the radiation sensitivity and c-fos expression in LM and AT cells. PKCI increased radiation induced apoptosis in LM cells but reduced apoptosis in AT cells. The basal c-fos transcription activity is 70 times lower in AT cells than that in LM cells. The c-fos transcription activity was repressed by overexpression of PKCI in LM cells but not in AT cells. After induction of c-fos by Ras protein, overexpression of PKCI repressed c-fos transcription in LM cells but not in AT cells Conclusion: Overexpression of PKCI increased radiation sensitivity and repressed c-fos transcription in LM cells but not in AT cells. The results may be a. reason of increased radiation sensitivity of AT cells. PKCI may be involved in an ionizing radiation induced signal transduction pathway responsible for radiation sensitivity and c-fos transcription. The data also provided evidence for novel transcriptional difference between LM and AT cells.

• 대한예방의학회:학술대회논문집
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• 2005.10a
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• pp.299-299
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• 2005

• BMB Reports
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• v.48 no.8
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• pp.454-460
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• 2015

Naturally occurring reoviruses are live replication-proficient viruses that specifically infect human cancer cells while sparing their normal counterpart. Since the discovery of reoviruses in 1950s, they have shown various degrees of safety and efficacy in pre-clinical or clinical applications for human anti-cancer therapeutics. I have recently discovered that cellular tumor suppressor genes are also important in determining reoviral tropism. Carcinogenesis is a multi-step process involving the accumulation of both oncogene and tumor suppressor gene abnormalities. Reoviruses can exploit abnormal cellular tumor suppressor signaling for their oncolytic specificity and efficacy. Many tumor suppressor genes such as p53, ataxia telangiectasia mutated (ATM), and retinoblastoma associated (RB) are known to play important roles in genomic fidelity/maintenance. Thus, a tumor suppressor gene abnormality could affect host genomic integrity and likely disrupt intact antiviral networks due to the accumulation of genetic defects which in turn could result in oncolytic reovirus susceptibility. This review outlines the discovery of oncolytic reovirus strains, recent progresses in elucidating the molecular connection between oncogene/tumor suppressor gene abnormalities and reoviral oncotropism, and their clinical implications. Future directions in the utility of reovirus virotherapy is also proposed in this review. [BMB Reports 2015; 48(8): 454-460]

• Molecules and Cells
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• v.42 no.3
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• pp.210-217
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• 2019

The maintenance of mitochondrial function is closely linked to the control of senescence. In our previous study, we uncovered a novel mechanism in which senescence amelioration in normal aging cells is mediated by the recovered mitochondrial function upon Ataxia telangiectasia mutated (ATM) inhibition. However, it remains elusive whether this mechanism is also applicable to senescence amelioration in accelerated aging cells. In this study, we examined the role of ATM inhibition on mitochondrial function in Hutchinson-Gilford progeria syndrome (HGPS) and Werner syndrome (WS) cells. We found that ATM inhibition induced mitochondrial functional recovery accompanied by metabolic reprogramming, which has been known to be a prerequisite for senescence alleviation in normal aging cells. Indeed, the induced mitochondrial metabolic reprogramming was coupled with senescence amelioration in accelerated aging cells. Furthermore, the therapeutic effect via ATM inhibition was observed in HGPS as evidenced by reduced progerin accumulation with concomitant decrease of abnormal nuclear morphology. Taken together, our data indicate that the mitochondrial functional recovery by ATM inhibition might represent a promising strategy to ameliorate the accelerated aging phenotypes and to treat age-related disease.

• BMB Reports
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• v.56 no.3
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• pp.166-171
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• 2023

Monocytes are peripheral leukocytes that function in innate immunity. Excessive triglyceride (TG) accumulation causes monocyte death and thus can compromise innate immunity. However, the mechanisms by which TG mediates monocyte death remain unclear to date. Thus, this study aimed to elucidate the mechanisms by which TG induces monocyte death. Results showed that TG induced monocyte death by activating caspase-3/7 and promoting poly (ADP-ribose) polymerase (PARP) cleavage. In addition, TG induced DNA damage and activated the ataxia telangiectasia mutated (ATM)/checkpoint kinase 2 and ATM-and Rad3-related (ATR)/checkpoint kinase 1 pathways, leading to the cell death. Furthermore, TG-induced DNA damage and monocyte death were mediated by caspase-2 and -8, and caspase-8 acted as an upstream molecule of caspase-2. Taken together, these results suggest that TG-induced monocyte death is mediated via the caspase-8/caspase-2/DNA damage/executioner caspase/PARP pathways.

• BMB Reports
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• v.56 no.10
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• pp.557-562
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• 2023

Dysregulation of the E3 ubiquitin ligase Parkin has been linked to various human cancers, indicating that Parkin is a tumor suppressor protein. However, the mechanisms of action of Parkin remain unclear to date. Thus, we aimed to elucidate the mechanisms of action of Parkin as a tumor suppressor in human lung and colorectal cancer cells. Results showed that Parkin overexpression reduced the viability of A549 human lung cancer cells by inducing G2/M cell cycle arrest. In addition, Parkin caused DNA damage and ATM (Ataxia telangiectasia mutated) activation, which subsequently led to p53 activation. It also induced the p53-mediated upregulation of p21 and downregulation of cyclin B1. Moreover, Parkin suppressed the proliferation of HCT-15 human colorectal cancer cells by a mechanism similar to that in A549 lung cancer cells. Taken together, our results suggest that the tumor-suppressive effects of Parkin on lung and colorectal cancer cells are mediated by DNA damage/p53 activation/cyclin B1 reduction/cell cycle arrest.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.52-52
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• 2021

Persicaria amphibia as an England native plant, is a rhizomatous perennial, one of the rather amphibious plants. Its aquatic form contains water-soluble sugars, starch, and protein. P. amphibia have up to 18% tannins in stems and rhizomes. Previous studies have confirmed the anti-inflammatory activity of live bacteria roots, but no studies on bioactivity are known. DNA damage responses (DDRs) pathways are considered a crucial factor affecting the alleviation of cellular damage. The ataxia-telangiectasia mutated and Rad3 related (ATM) and checkpoint kinase 2 (Chk2) pathways are the main pathways of DNA damage response. Also, p53 is a key integrator of cellular response to oxidative DNA damage, contributing repair, or leading transcription including apoptosis. In the present study, we conducted an investigation into the inhibitory effects of P. amphibia on oxidative DNA damage for confirming potential to complementary medicine and therapies. In conclusion, P. amphibia can provide protective effects against double-stranded DNA break (DSB) caused by oxidative DNA damage.

• Biomolecules & Therapeutics
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• v.23 no.6
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• pp.517-524
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• 2015

Human mesenchymal stem cells (MSCs) have been used in cell-based therapy to promote revascularization after peripheral or myocardial ischemia. High levels of reactive oxygen species (ROS) are involved in the senescence and apoptosis of MSCs, causing defective neovascularization. Here, we examined the effect of the natural antioxidant lycopene on oxidative stress-induced apoptosis in MSCs. Although $H_2O_2$ ($200{\mu}M$) increased intracellular ROS levels in human MSCs, lycopene ($10{\mu}M$) pretreatment suppressed $H_2O_2$-induced ROS generation and increased survival. $H_2O_2$-induced ROS increased the levels of phosphorylated p38 mitogen activated protein kinase (MAPK), Jun-N-terminal kinase (JNK), ataxia telangiectasia mutated (ATM), and p53, which were inhibited by lycopene pretreatment. Furthermore, lycopene pretreatment decreased the expression of cleaved poly (ADP ribose) polymerase-1 (PARP-1) and caspase-3 and increased the expression of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax), which were induced by $H_2O_2$ treatment. Moreover, lycopene significantly increased manganese superoxide dismutase (MnSOD) expression and decreased cellular ROS levels via the PI3K-Akt pathway. Our findings show that lycopene pretreatment prevents ischemic injury by suppressing apoptosis-associated signal pathway and enhancing anti-oxidant protein, suggesting that lycopene could be developed as a beneficial broad-spectrum agent for the successful MSC transplantation in ischemic diseases.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.584-590
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• 2017

Ginkgo biloba extract (EGb 761) has been widely used clinically to reduce myocardial ischemia reperfusion injury (MIRI). Microvascular endothelial cells (MVECs) may be a proper cellular model in vitro for the effect and mechanism study against MIRI. However, the protective effect of EGb 761 on MVECs resisting hypoxia/reoxygenation (H/R) injury is little reported. In this study, H/R-injured MVECs were treated with EGb 761, and then the cell viability, apoptosis, ROS production, SOD activity, caspase-3 activity, and protein level of ATM, ${\gamma}$-H2AX, p53, and Bax were measured. ATM siRNA was transfected to study the changes of protein in the ATM pathway. EGb 761 presented protective effect on H/R-injured MVECs, with decreasing cell death, apoptosis, and ROS, and elevated SOD activity. Next, EGb 761 could inhibit H/R-induced ATM, ${\gamma}$-H2AX, p53, and Bax in a dose-dependent manner. Moreover, ATM siRNA also could inhibit H/R-induced ATM, ${\gamma}$-H2AX, p53, and Bax. Overall, these findings verify that EGb 761 protects cardiac MVECs from H/R injury, and for the first time, illustrate the influence on the ATM pathway and apoptosis by EGb 761 via dampening ROS.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.815-821
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• 2016

Background: Development of chronic myeloid leukemia (CML) involves formation of double strand breaks (DSBs) which are initially sensed by the ataxia telangiectasia mutated (ATM) signal kinase to induce a DNA damage response (DDR). Mutations or single nucleotide polymorphisms in ATM gene are known to influence the signaling capacity resulting in susceptibility to certain genetic diseases such as cancers. Materials and Methods: In the present study, we have analyzed -5144A>T (rs228589) and C4138T (rs3092856) polymorphisms of theATM gene through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 925 subjects (476 CML cases and 449 controls). Results: The A allele of -5144A>T polymorphism and T allele of C4138T polymorphism which were known to be influencing ATM signaling capacity are significantly associated with enhanced risk for CML independently and also in combination (evident from the haplotype and diplotype analyses). Significant elevation in the frequencies of both the risk alleles among high risk groups under European Treatment and Outcome Study (EUTOS) score suggests the possible role of these polymorphisms in predicting the prognosis of CML patients. Conclusions: This study provides the first evidence of association of functional ATM gene polymorphisms with the increased risk of CML development as well as progression.