Basic Performance Evaluation of a Radiation Survey Meter That Uses a Plastic-Scintillation Sensor.

After the Fukushima nuclear power plant accident in 2011, many types of survey meters were used, including Geiger-Müller (GM) survey meters, which have long been used to measure ß-rays. Recently, however, a novel radiation survey meter that uses a plastic-scintillation sensor has been developed. Although manufacturers' catalog data are available for these survey meters, there have been no user reports on performance. In addition, the performance of commercial plastic-scintillation survey meters has not been evaluated. In this study, we experimentally compared the performance of a plastic-scintillation survey meter with that of a GM survey meter. The results show that the two instruments performed very similarly in most respects. The GM survey meter exhibited count losses when the radiation count rate was high, whereas the plastic-scintillation survey meter remained accurate under such circumstances, with almost no count loss at high radiation rates. For measurements at background rates (i.e., low counting rates), the counting rates of the plastic-scintillation and GM survey meters were similar. Therefore, an advantage of plastic-scintillation survey meters is that they are less affected by count loss than GM survey meters. We conclude that the plastic-scintillation survey meter is a useful ß-ray measuring/monitoring instrument.

AMPK/FOXO3a Pathway Increases Activity and/or Expression of ATM, DNA-PKcs, Src, EGFR, PDK1, and SOD2 and Induces Radioresistance under Nutrient Starvation.

Most solid tumors contain hypoxic and nutrient-deprived microenvironments. The cancer cells in these microenvironments have been reported to exhibit radioresistance. We have previously reported that nutrient starvation increases the expression and/or activity of ATM and DNA-PKcs, which are involved in the repair of DNA double-strand breaks induced by ionizing radiation. In the present study, to elucidate the molecular mechanisms underlying these phenomena, we investigated the roles of AMPK and FOXO3a, which play key roles in the cellular response to nutrient starvation. Nutrient starvation increased clonogenic cell survival after irradiation and increased the activity and/or expression of AMPKα, FOXO3a, ATM, DNA-PKcs, Src, EGFR, PDK1, and SOD2 in MDA-MB-231 cells. Knockdown of AMPKα using siRNA suppressed the activity and/or expression of FOXO3a, ATM, DNA-PKcs, Src, EGFR, PDK1, and SOD2 under nutrient starvation. Knockdown of FOXO3a using siRNA suppressed the activity and/or expression of AMPKα, ATM, DNA-PKcs, FOXO3a, Src, EGFR, PDK1, and SOD2 under nutrient starvation. Nutrient starvation decreased the incidence of apoptosis after 8 Gy irradiation. Knockdown of FOXO3a increased the incidence of apoptosis after irradiation under nutrient starvation. AMPK and FOXO3a appear to be key molecules that induce radioresistance under nutrient starvation and may serve as targets for radiosensitization.

AMPK increases expression of ATM through transcriptional factor Sp1 and induces radioresistance under severe hypoxia in glioblastoma cell lines.

We have previously reported that severe hypoxia increases expression and activity of the DNA damage sensor ATM by activation of the key energy sensor AMPK. Here, to elucidate molecular mechanisms underlying increased expression and activity of ATM by AMPK under severe hypoxia, we investigated roles of transcriptional factors Sp1 and FoxO3a using human glioblastoma cell lines T98G and A172. Severe hypoxia increased expression of ATM, AMPKα and Sp1 but not that of FoxO3a. Knockdown of AMPKα suppressed expression of ATM and Sp1 and suppressed cellular radioresistance under severe hypoxia without affecting cell cycle distribution. Knockdown of Sp1 suppressed expression of ATM. These results suggest that increased expression and activity of AMPK under severe hypoxia induce cellular radioresistance through AMPK/Sp1/ATM pathway.

Design, synthesis and biological evaluation of 2-pyrrolone derivatives as radioprotectors.

It is known that p53 is an important transcription factor and plays a central role in ionizing radiation (IR)-induced DNA damage responses such as cell cycle arrest, DNA repair and apoptosis. We previously reported that regulating p53 protein is an effective strategy for modulating cell fate by reducing the acute side effects of radiation therapy. Herein, we report on the discovery of STK160830 as a new radioprotector from a chemical library at The University of Tokyo and the design, synthesis and biological evaluation of its derivatives. The radioprotective activity of STK160830 itself and its derivatives that were synthesized in this work was evaluated using a leukemia cell line, MOLT-4 cells as a model of normal cells that express the p53 protein in a structure-activity relationships (SAR) study. The experimental results suggest that a direct relationship exists between the inhibitory effect of these STK160830 derivatives on the expression level of p53 and their radioprotective activity and that the suppression of p53 by STK160830 derivatives contribute to protecting MOLT-4 cells from apoptosis that is induced by exposure to radiation.

DNA-PKcs is activated under nutrient starvation and activates Akt, MST1, FoxO3a, and NDR1.

BACKGROUND: Presence of unperfused regions containing cells under hypoxia and nutrient starvation; contributes to radioresistance in solid human tumors. We have previously reported that cultured cells; under nutrient starvation show resistance to ionizing radiation compare with cells under normal; condition, and that nutrient starvation increases ATM activity, which causes cellular resistance to; ionizing radiation (Murata et al., BBRC2018). For further investigation of molecular mechanisms; underlying radioresistance of cells under nutrient starvation, effects of nutrient starvation on activity; of DNA-PKcs have been investigated because both DNA-PKcs and ATM belong to the PIKK family; and are required for DNA DSBs repair. In addition to DNA-PKcs, effects of nutrient starvation on; activities of FoxO3a and its regulators Akt, MST1 and AMPK have been investigated because FoxO3a; mediates cellular responses to stress and is activated under nutrient starvation. METHODS: A human glioblastoma cell line, T98G was used to examine the effects of nutrient starvation on activities and expression of DNA-PKcs, Akt, MST1, FoxO3a, NDR1, and AMPK. To elucidate; signal transduction pathways for FoxO3a activation under nutrient starvation, we examined effects of; specific inhibitors or siRNA for DNA-PKcs or Akt on activities and expression of MST1, FoxO3, NDR1, andAMPK. RESULTS: Under nutrient starvation, phosphorylations of DNA-PKcs at Ser2056, Akt at Ser473, MST at Thr183, FoxO3a at Ser413, NDR1 at Ser281 and Thr282, and AMPK at Thr172 were increased, which suggests their activation. Nutrient starvation did not affect expression of DNA-PKcs, Akt, MST1, or NDR1, with decreased expression of FoxO3a and increased expression of AMPK. Inhibition; of DNA-PK suppressed phosphorylation of Akt under nutrient starvation. Inhibition of DNA-PK or; Akt suppressed phosphorylations of MST1, FoxO3a, and NDR1 under nutrient starvation, which; suggests DNA-PKcs and Akt activate MST1, FoxO3a, and NDR1. Inhibition of DNA-PK did not; suppress phosphorylation ofAMPK under nutrient starvation. CONCLUSION: Our data suggest that DN-PKcs is activated under nutrient starvation and activates AktMST1, FoxO3a, and NDR1.

Severe hypoxia increases expression of ATM and DNA-PKcs and it increases their activities through Src and AMPK signaling pathways.

BACKGROUND: Solid tumors often contain hypoxic regions because an abnormal and inefficient tumor vasculature is unable to supply sufficient oxygen. Tissue hypoxia is generally defined as a low oxygen concentration of less than 2%. It is well known that tumor cells under severe hypoxia, where oxygen concentration is less than 0.1%, show radioresistance. It has been reported that cells under severe hypoxia show different responses from those under mild hypoxia, where oxygen concentration is 0.5-2.0%. In the present study, we investigated the effects of severe hypoxia on expression and activities of ATM and DNA-dependent protein kinase catalytic subunit (DNA-PKcs), both of which regulate DNA double-strand breaks (DSBs) repair and radiation sensitivity. Signaling pathways for increasing expression and activities of ATM and DNA-PKcs under severe hypoxia were also investigated. METHODS: SV40-transformed human fibroblast cell lines, LM217 and LM205, and normal human dermal fibroblasts (NHDF) were used. Cells were cultured at an oxygen concentration of less than 0.05% for 12 or 24 h. Activities and/or expression of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, HIF-1α, PDK1, Akt, AMPKα, and mTOR were estimated by Western blot analyses. RESULTS: Severe hypoxia increased expression and activities of ATM, DNA-PKcs, Src, Caveolin-1, EGFR, PDK1, Akt, and AMPKα, and decreased expression and activity of mTOR. A specific Src inhibitor, PP2 suppressed activation of ATM, DNA-PKcs, Caveolin-1, EGFR, and Akt under severe hypoxia. Treatment with siRNA for AMPKα suppressed activation of ATM and DNA-PKcs and increase of ATM expression under severe hypoxia. CONCLUSION: Our data show that severe hypoxia increases activities of ATM and DNA-PKcs through Src and AMPK signaling pathways, and that activation of AMPK under hypoxia causes increase of ATM expression. Since ATM and DNA-PKcs play important roles in DSBs repair induced by ionizing radiation, those data provide novel insights on the molecular mechanism of the cellular radioresistance under severe hypoxia.

Knockdown of AMPKα decreases ATM expression and increases radiosensitivity under hypoxia and nutrient starvation in an SV40-transformed human fibroblast cell line, LM217.

BACKGROUND: Presence of unperfused regions containing cells under hypoxia and nutrient starvation contributes to radioresistance in solid human tumors. It is well known that hypoxia causes cellular radioresistance, but little is known about the effects of nutrient starvation on radiosensitivity. We have reported that nutrient starvation induced decrease of mTORC1 activity and decrease of radiosensitivity in an SV40-transformed human fibroblast cell line, LM217, and that nutrient starvation induced increase of mTORC1 activity and increase of radiosensitivity in human liver cancer cell lines, HepG2 and HuH6 (Murata et al., BBRC 2015). Knockdown of mTOR using small interfering RNA (siRNA) for mTOR suppressed radiosensitivity under nutrient starvation alone in HepG2 cells, which suggests that mTORC1 pathway regulates radiosensitivity under nutrient starvation alone. In the present study, effects of hypoxia and nutrient starvation on radiosensitivity were investigated using the same cell lines. METHODS: LM217 and HepG2 cells were used to examine the effects of hypoxia and nutrient starvation on cellular radiosensitivity, mTORC1 pathway including AMPK, ATM, and HIF-1α, which are known as regulators of mTORC1 activity, and glycogen storage, which is induced by HIF-1 and HIF-2 under hypoxia and promotes cell survival. RESULTS: Under hypoxia and nutrient starvation, AMPK activity and ATM expression were increased in LM217 cells and decreased in HepG2 cells compared with AMPK activity under nutrient starvation alone or ATM expression under hypoxia alone. Under hypoxia and nutrient starvation, radiosensitivity was decreased in LM217 cells and increased in HepG2 cells compared with radiosensitivity under hypoxia alone. Under hypoxia and nutrient starvation, knockdown of AMPK decreased ATM activity and increased radiation sensitivity in LM217 cells. In both cell lines, mTORC1 activity was decreased under hypoxia and nutrient starvation. Under hypoxia alone, knockdown of mTOR slightly increased ATM expression but did not affect radiosensitivity in LM217. Under hypoxia and nutrient starvation, HIF-1α expression was suppressed and glycogen storage was reduced. CONCLUSION: Our data suggest that AMPK regulates ATM expression and partially regulates radiosensitivity under hypoxia and nutrient starvation. The molecular mechanism underlying the induction of ATM expression by AMPK remains to be elucidated.

NSAIDs diclofenac, indomethacin, and meloxicam highly upregulate expression of ICAM-1 and COX-2 induced by X-irradiation in human endothelial cells.

BACKGROUND: It is well known that radiation exposure to the heart and the use of non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of myocardial infarction (MI). Some NSAIDs are also known to act synergistically with ionizing radiation and have radio-sensitizing effects in radiotherapy. These evidences suggest that NSAIDs may affect the risk of MI after radiation exposure to the heart. In the present study, we investigated effects of NSAIDs on radiation-induced expression of cell adhesion molecules and COX-2, which are associated with inflammation and an increased risk of MI, in human endothelial cells. METHODS: Effects of NSAIDs on radiation-induced expression of ICAM-1, VCAM-1, E-selectin, and COX-2 were investigated in human umbilical vein endothelial cells (HUVECs). As NSAIDs, diclofenac, etodolac, indomethacin, ketoprofen, meloxicam, and rofecoxib were used. RESULTS: Irradiation with 10 Gy increased expression of ICAM-1 and COX-2, but it did not affect expression of VCAM-1 or E-selectin. All the NSAIDs upregulated radiation-induced expression of ICAM-1 and COX-2. The extent of upregulation varied depending on the types of NSAIDs. Indomethacin, diclofenac, and meloxicam highly upregulated radiation-induced expression of ICAM-1 and COX-2. The extent of upregulation was not related to the degree of COX-2 selectivity. An NF-κB inhibitor BAY 11-7082 suppressed radiation-induced expression of ICAM-1, but it did not suppress upregulated expression of ICAM-1 or COX-2 by combination treatment with X-irradiation and meloxicam, suggesting the existence of NF-κB-independent pathways for ICAM-1 and COX-2 induction. CONCLUSION: Indomethacin, diclofenac, and meloxicam highly upregulated radiation-induced expression of ICAM-1 and COX-2 in HUVECs, which suggests that use of these NSAIDs may increase the effects of ionizing radiation and affect the risk of MI after radiation exposure to the heart.

Activation of mTORC1 under nutrient starvation conditions increases cellular radiosensitivity in human liver cancer cell lines, HepG2 and HuH6.

BACKGROUND: The presence of unperfused regions containing cells under hypoxic and nutrient starvation conditions contributes to radioresistance in solid human tumors. It is well known that the hypoxia causes cellular radioresistance. However, the effects of nutrient starvation conditions on cellular radiosensitivity remain unclear. METHODS: Human liver cancer cell lines, HepG2 and HuH6, and a SV40-transformed human fibroblast cell line, LM217 were used to examine the effects of nutrient starvation conditions on cellular radiosensitivity and on activity of mammalian target of rapamycin complex 1 (mTORC1) that senses cellular nutrient conditions and affects radiosensitivity. RESULTS: In contrast to suppressed mTORC1 activity under nutrient starvation conditions in LM217, HepG2 and HuH6 cells showed increased mTORC1 activity under nutrient starvation conditions. Both AMP-activated protein kinase (AMPK) and Akt were activated under nutrient starvation conditions in all the three cell lines. Under starvation conditions, increased radiosensitivity was observed in HepG2 and HuH6 cells, in contrast to decreased radiosensitivity in LM217 cells. Knockdown of mTOR using siRNA for mTOR or treatment with a mTOR inhibitor, rapamycin, suppressed the increased radiosensitivity under starvation conditions in HepG2 cells. CONCLUSION: Our data show for the first time that nutrient starvation conditions activate mTORC1 and increase radiosensitivity through mTORC1 activation in liver cancer cell lines, HepG2 and HuH6.

Inhibition of ß-catenin and STAT3 with a curcumin analog suppresses gastric carcinogenesis in vivo.

BACKGROUND: Potent chemotherapy for advanced gastric cancer has not been completely established. Many molecularly targeted therapies are under investigation, but their therapeutic outcomes are not promising because they do not target specific and/or critical targets of gastric carcinogenesis. Although the molecular basis of gastric carcinogenesis remains poorly understood, nuclear localization of ß-catenin was observed in approximately 50 % of gastric cancer specimens. Recent studies have suggested that activation of signal transducer and activator of transcription 3 (STAT3) contributes to gastric carcinogenesis in a mouse model. A newly synthesized curcumin analog has inhibitory potential against ß-catenin and STAT3. METHODS: Using a transgenic mouse model of gastric cancer in which ß-catenin, cyclooxygenase 2, and microsomal prostaglandin E synthase 1 activation is induced, we examined a curcumin analog with the most enhanced potential for treating gastric cancer through oral administration. Inhibition of these targets was demonstrated using microarray and immunohistochemical analyses. RESULTS: The curcumin analog GO-Y031 decreased the incidence of gastric carcinogenesis to 54.5 % of that of the control (50.0 % vs 91.7 %, p = 0.043), and tumor size was reduced to 51.6 % of that of the control (1.6 mm vs 3.1 mm, p = 0.03). ß-Catenin and STAT3 levels were suppressed to 26.2 % (p = 0.00023) and 44.8 % (p = 0.025), respectively, of those of the control. Moreover, macrophage infiltration was suppressed with GO-Y031. CONCLUSION: ß-Catenin and STAT3 can be pharmacologically inhibited in vivo with a curcumin analog, which effectively inhibits ß-catenin and STAT3.

Mitochondria are required for ATM activation by extranuclear oxidative stress in cultured human hepatoblastoma cell line Hep G2 cells.

Ataxia-telangiectasia mutated (ATM) is a serine/threonine protein kinase that plays a central role in DNA damage response (DDR). A recent study reported that oxidized ATM can be active in the absence of DDR. However, the issue of where ATM is activated by oxidative stress remains unclear. Regarding the localization of ATM, two possible locations, namely, mitochondria and peroxisomes are possible. We report herein that ATM can be activated when exposed to hydrogen peroxide without inducing nuclear DDR in Hep G2 cells, and the oxidized cells could be subjected to subcellular fractionation. The first detergent-based fractionation experiment revealed that active, phosphorylated ATM was located in the second fraction, which also contained both mitochondria and peroxisomes. An alternative fractionation method involving homogenization and differential centrifugation, which permits the light membrane fraction containing peroxisomes to be produced, but not mitochondria, revealed that the light membrane fraction contained only traces of ATM. In contrast, the heavy membrane fraction, which mainly contained mitochondrial components, was enriched in ATM and active ATM, suggesting that the oxidative activation of ATM occurs in mitochondria and not in peroxisomes. In Rho 0-Hep G2 cells, which lack mitochondrial DNA and functional mitochondria, ATM failed to respond to hydrogen peroxide, indicating that mitochondria are required for the oxidative activation of ATM. These findings strongly suggest that ATM can be activated in response to oxidative stress in mitochondria and that this occurs in a DDR-independent manner.

[Radiation carcinogenesis].

Misrepair of DNA damage induced by ionizing radiation is a potential cause of carcinogenesis following exposure to radiation. Radiation exposure increases the incidence of the same types of mutations that occur spontaneously in a given population. A high incidence of DNA double-strand breaks is characteristic of damage by ionizing radiation compared with those induced by other environmental mutagens. In China, residents living in areas with high level background radiation(6mSv/y) had a significantly higher frequency of dicentric and ring chromosomes compared to that for the residents living in the control areas(2mSv/y). Radiation-associated increases in risk were seen for most sites. Gender-averaged excess absolute risk rates estimated at age 70, after exposure at age 30, differ in the sites, and the risks of gastric cancer, breast cancer, colon cancer, and lung cancer were highly increased, in that order. Latent periods for the development of leukemia and thyroid cancer after radiation exposure at ages younger than 18 were shorter compared to those for other solid cancers.

A Novel RNA Synthesis Inhibitor, STK160830, Has Negligible DNA-Intercalating Activity for Triggering A p53 Response, and Can Inhibit p53-Dependent Apoptosis.

RNA synthesis inhibitors and protein synthesis inhibitors are useful for investigating whether biological events with unknown mechanisms require transcription or translation; however, the dependence of RNA synthesis has been difficult to verify because many RNA synthesis inhibitors cause adverse events that trigger a p53 response. In this study, we screened a library containing 9600 core compounds and obtained STK160830 that shows anti-apoptotic effects in irradiated wild-type-p53-bearing human T-cell leukemia MOLT-4 cells and murine thymocytes. In many of the p53-impaired cells and p53-knockdown cells tested, STK160830 did not show a remarkable anti-apoptotic effect, suggesting that the anti-apoptotic activity is p53-dependent. In the expression analysis of p53, p53-target gene products, and reference proteins by immunoblotting, STK160830 down-regulated the expression of many of the proteins examined, and the downregulation correlated strongly with its inhibitory effect on cell death. mRNA expression analyses by qPCR and nascent RNA capture kit revealed that STK160830 showed a decreased mRNA expression, which was similar to that induced by the RNA synthesis inhibitor actinomycin D but differed to some extent. Furthermore, unlike other RNA synthesis inhibitors such as actinomycin D, p53 accumulation by STK160830 alone was negligible, and a DNA melting-curve analysis showed very weak DNA-intercalating activity, indicating that STK160830 is a useful inhibitor for RNA synthesis without triggering p53-mediated damage responses.

Isorhamnetin Promotes 53BP1 Recruitment through the Enhancement of ATM Phosphorylation and Protects Mice from Radiation Gastrointestinal Syndrome.

Flavonoids are a subclass of polyphenols which are attractive, due to possessing various physiological activities, including a radioprotective effect. Tumor suppressor p53 is a primary regulator in the radiation response and is involved in the pathogenesis of radiation injuries. In this study, we revealed that isorhamnetin inhibited radiation cell death, and investigated its action mechanism focusing on DNA damage response. Although isorhamnetin moderated p53 activity, it promoted phosphorylation of ataxia telangiectasia mutated (ATM) and enhanced 53BP1 recruitment in irradiated cells. The radioprotective effect of isorhamnetin was not observed in the presence of ATM inhibitor, indicating that its protective effect was dependent on ATM. Furthermore, isorhamnetin-treated mice survived gastrointestinal death caused by a lethal dose of abdominal irradiation. These findings suggested that isorhamnetin enhances the ATM-dependent DNA repair process, which is presumably associated with the suppressive effect against GI syndrome.

Preoperative radiation response evaluated by 18-fluorodeoxyglucose positron emission tomography predicts survival in locally advanced rectal cancer.

PURPOSE: This study focuses on the prognostic survival value of postirradiation metabolic activity in primary rectal cancer as measured with 18-fluorodeoxyglucose positron emission tomography. METHODS: From July 1995 to March 2002, all 59 patients underwent two series of fluorodeoxyglucose positron emission tomography: one before preoperative radiation (standardized uptake values-1), and the other two to three weeks after radiation (standardized uptake values-2). Standardized uptake values-1 and standardized uptake values-2 correspond to before and after radiation, respectively. RESULTS: In univariate analysis, the following emerged as significant prognostic variables: with or without residual tumor, pathologic differentiation, with or without recurrence, standardized uptake values-2, and with or without lymph node metastases. In multivariate analysis, residual tumor and standardized uptake values-2 were significant prognostic factors for survival. The median survival and the five-year overall survival rate comparing standardized uptake values-2 values <5 vs. >5 were 95 vs. 42 months and 70 vs. 44 percent, respectively (P = 0.042). CONCLUSION: A significant survival benefit was observed in patients with low fluorodeoxyglucose uptake after preoperative radiotherapy in primary tumors of rectal cancer.

Pathological changes in the gastrointestinal tract of a heavily radiation-exposed worker at the Tokai-mura criticality accident.

Gastrointestinal syndrome after high-dose acute radiation whole body exposure is difficult to treat, although it is a well-known complication. In this report, we describe the clinical and pathological features of a patient who died after the criticality accident which occurred in Japan on 30 September 1999. The patient was estimated to have been exposed to 16-25 Gy equivalent of gamma ray, and died of multiple organ failure after acute radiation syndrome, especially gastrointestinal syndrome, on day 82. The stomach and small intestine contained a large amount of blood clots and the gastrointestinal epithelial cells were almost totally depleted at autopsy. In addition, the degree of the mucosal damage was dependent on the segment of the gastrointestinal tract; the mucosa of stomach, ileum and ascending colon was entirely depleted, but the esophagus, descending and sigmoid colon and rectum retained a small portion of the epithelial cells. From the posture of the patient at the time of exposure, the absorbed dose was presumed to be highest in the right-anterior abdomen. This agreed with the pathological differences in the mucosal damage by the position in the abdomen, which depended presumably on the radiation dose. This is the first report documenting the relationship between the absorbed dose and the severity of gastrointestinal damages in vivo.

A Chemical Modulator of p53 Transactivation that Acts as a Radioprotective Agonist.

Inhibiting p53-dependent apoptosis by inhibitors of p53 is an effective strategy for preventing radiation-induced damage in hematopoietic lineages, while p53 and p21 also play radioprotective roles in the gastrointestinal epithelium. We previously identified some zinc(II) chelators, including 8-quinolinol derivatives, that suppress apoptosis in attempts to discover compounds that target the zinc-binding site in p53. We found that 5-chloro-8-quinolinol (5CHQ) has a unique p53-modulating activity that shifts its transactivation from proapoptotic to protective responses, including enhancing p21 induction and suppressing PUMA induction. This p53-modulating activity also influenced p53 and p53-target gene expression in unirradiated cells without inducing DNA damage. The specificity of 5CHQ for p53 and p21 was demonstrated by silencing the expression of each protein. These effects seem to be attributable to the sequence-specific alteration of p53 DNA-binding, as evaluated by chromatin immunoprecipitation and electrophoretic mobility shift assays. In addition, 5-chloro-8-methoxyquinoline itself had no antiapoptotic activity, indicating that the hydroxyl group at the 8-position is required for its antiapoptotic activity. We applied this remarkable agonistic activity to protecting the hematopoietic and gastrointestinal system in mouse irradiation models. The dose reduction factors of 5CHQ in total-body and abdominally irradiated mice were about 1.2 and 1.3, respectively. 5CHQ effectively protected mouse epithelial stem cells from a lethal dose of abdominal irradiation. Furthermore, the specificity of 5CHQ for p53 in reducing the lethality induced by abdominal irradiation was revealed in Trp53-KO mice. These results indicate that the pharmacologic upregulation of radioprotective p53 target genes is an effective strategy for addressing the gastrointestinal syndrome. Mol Cancer Ther; 17(2); 432-42. ©2017 AACRSee all articles in this MCT Focus section, "Developmental Therapeutics in Radiation Oncology."

Free radical scavenger edaravone suppresses x-ray-induced apoptosis through p53 inhibition in MOLT-4 cells.

Edaravone, a clinical drug used widely for the treatment of acute cerebral infarction, is reported to scavenge free radicals. In the present study, we investigated the radioprotective effect of edaravone on X-ray-induced apoptosis in MOLT-4 cells. Apoptosis was determined by the dye exclusion test, Annexin V binding assay, cleavage of caspase, and DNA fragmentation. We found that edaravone significantly suppressed the X-ray-induced apoptosis. The amount of intracellular ROS production was determined by the chloromethyl-2',7'-dichlorodihydro-fluorescein diacetate system. We found that the intracellular ROS production by X-irradiation was completely suppressed by the addition of edaravone. The accumulation and phosphorylation of p53 and the expression of p21(WAF1), a target protein of p53, which were induced by X-irradiation, were also suppressed by adding edaravone. We conclude that the free radical scavenger edaravone suppresses X-ray-induced apoptosis in MOLT-4 cells by inhibiting p53.

Relation between acute and late irradiation impairment of four basic tastes and irradiated tongue volume in patients with head-and-neck cancer.

PURPOSE: Taste loss is a major cause of morbidity in patients undergoing head-and-neck irradiation. The relationship between the time course and the degree of taste disorder was studied in both acute and late phases. METHODS AND MATERIALS: Taste ability was measured by the taste threshold for the four basic tastes using a filter paper disc method in patients before, during, and after radiotherapy. The subjects were divided into two groups. In Group A, the radiation fields included most of the tongue (n = 100), and in Group B the radiation fields did not include the tip of the tongue (n = 18). RESULTS: In Group A, there was a significant impairment of the threshold of all four basic tastes at 3 weeks after starting radiotherapy (RT), and this impairment remained at 8 weeks (p < 0.05). This was not seen in Group B. In Group A, there was no significant difference in the patterns of taste sensitivity change between the high-dose (>20 Gy) and low-dose (< or =20 Gy) groups. In the late phase, recovery of taste loss was seen in both groups since 4 months after completing RT. CONCLUSIONS: Unless the anterior part of the tongue was irradiated, taste loss was not observed during RT. When the anterior part of the tongue was irradiated, a difference by radiation dose was not observed in the taste loss pattern. Additionally, radiation-induced taste dysfunction appears to be a temporal effect.