In vivo gamma-rays induced initial DNA damage and the effect of famotidine in mouse leukocytes as assayed by the alkaline comet assay

Evaluating the radioprotective effect of green barley juice on male rats

PURPOSE

DNA damage accounts for most biological effects of ionizing radiation. Antioxidants are known for their protective effect by preventing DNA damage. This pilot study aimed to evaluate the potential radioprotective effect of Natural SOD®, a green barley juice rich in antioxidants, on DNA damage in the testes and lymphocytes of Wistar rats exposed to ionizing radiation.

MATERIALS AND METHODS

Male Wistar rats (n = 15) were selected and equally divided into three groups. Rats in one of the groups were pretreated orally with Natural SOD® for 14 days, while rats in another group were sham-pretreated with saline solution. Rats in both these groups were afterwards subjected to a single dose of 6 Gy X-ray whole-body irradiation. The control group did not receive any treatment and was not irradiated. Shortly after X-ray exposure, all rats were sacrificed and testes and blood were collected. Gamma-H2AX and histopathological assessment in the testes, along with comet assay of lymphocytes were performed.

RESULTS

Histopathological examination of the testes showed no significant architectural alterations. Immunofluorescent staining of γ-H2AX revealed more DNA double-strand break sites in testicular cells from sham animals compared to Natural SOD® pretreated rats. Alkaline comet assay results showed increased DNA damage in lymphocytes of irradiated rats compared to the control group with little differences between the pretreated groups. Animals pretreated with Natural SOD showed slightly reduced DNA damage compared to sham-pretreated rats. These findings suggest a potential protective effect of Natural SOD® against radiation-induced DNA damage.

CONCLUSIONS

Natural SOD® exhibited a potential prophylactic radioprotective effect in rats, particularly in testes. Further investigations to determine medium and long-term effects of X-ray in animals administered Natural SOD® are needed to better estimate the radioprotective effect.

Effectiveness of oral famotidine in reducing the hematologic complications of radiotherapy in patients with esophageal and cardia cancers: a randomized controlled trial

BACKGROUND

Chemoradiotherapy complications has always been of great concern to both clinicians and patients during the course of treatment. The purpose of the present study was to examine the effectiveness of oral famotidine on the reduction of hematologic complications of patients with esophageal and gastric cardia cancers undergoing radiotherapy.

METHODS

A single-blind controlled trial was conducted on 60 patients with esophageal and cardia cancers, who were undergoing chemoradiotherapy. Patients were randomly assigned to 2 groups with 30 patients to receive either 40 mg of oral famotidine (daily and 4 h before each session) or placebo. Complete blood count with differential, platelet counts, and hemoglobin levels were obtained weekly during treatment. The main outcome variables were lymphocytopenia, granulocytopenia, thrombocytopenia, and anemia.

RESULTS

The findings indicated a significant effect of famotidine on reduction of thrombocytopenia among intervention group compared to control group (P < 0.0001). Even so, the effect of intervention was not significant for other outcome variables (All, P ≥ 0.05). The lymphocyte (P = 0.007) and platelet (P = 0.004) counts were also significantly greater in famotidine group in comparison with placebo group at the end of the study.

CONCLUSION

As evidenced by the findings of the current study, famotidine might be recommended as an effective radioprotective agent among patients with esophageal and gastric cardia cancers to prevent Leukocyte and platelet reduction to some extent. Trial registration This study was prospectively registered at irct.ir (Iranian Registry of Clinical Trials) with the code IRCT20170728035349N1, 2020-08-19.

Metabolic Rewiring in Radiation Oncology Toward Improving the Therapeutic Ratio

To meet the anabolic demands of the proliferative potential of tumor cells, malignant cells tend to rewire their metabolic pathways. Although different types of malignant cells share this phenomenon, there is a large intracellular variability how these metabolic patterns are altered. Fortunately, differences in metabolic patterns between normal tissue and malignant cells can be exploited to increase the therapeutic ratio. Modulation of cellular metabolism to improve treatment outcome is an emerging field proposing a variety of promising strategies in primary tumor and metastatic lesion treatment. These strategies, capable of either sensitizing or protecting tissues, target either tumor or normal tissue and are often focused on modulating of tissue oxygenation, hypoxia-inducible factor (HIF) stabilization, glucose metabolism, mitochondrial function and the redox balance. Several compounds or therapies are still in under (pre-)clinical development, while others are already used in clinical practice. Here, we describe different strategies from bench to bedside to optimize the therapeutic ratio through modulation of the cellular metabolism. This review gives an overview of the current state on development and the mechanism of action of modulators affecting cellular metabolism with the aim to improve the radiotherapy response on tumors or to protect the normal tissue and therefore contribute to an improved therapeutic ratio.

Commonalities Between COVID-19 and Radiation Injury

As the multi-systemic components of COVID-19 emerge, parallel etiologies can be drawn between SARS-CoV-2 infection and radiation injuries. While some SARS-CoV-2-infected individuals present as asymptomatic, others exhibit mild symptoms that may include fever, cough, chills, and unusual symptoms like loss of taste and smell and reddening in the extremities (e.g., "COVID toes," suggestive of microvessel damage). Still others alarm healthcare providers with extreme and rapid onset of high-risk indicators of mortality that include acute respiratory distress syndrome (ARDS), multi-organ hypercoagulation, hypoxia and cardiovascular damage. Researchers are quickly refocusing their science to address this enigmatic virus that seems to unveil itself in new ways without discrimination. As investigators begin to identify early markers of disease, identification of common threads with other pathologies may provide some clues. Interestingly, years of research in the field of radiation biology documents the complex multiorgan nature of another disease state that occurs after exposure to high doses of radiation: the acute radiation syndrome (ARS). Inflammation is a key common player in COVID-19 and ARS, and drives the multi-system damage that dramatically alters biological homeostasis. Both conditions initiate a cytokine storm, with similar pro-inflammatory molecules increased and other anti-inflammatory molecules decreased. These changes manifest in a variety of ways, with a demonstrably higher health impact in patients having underlying medical conditions. The potentially dramatic human impact of ARS has guided the science that has identified many biomarkers of radiation exposure, established medical management strategies for ARS, and led to the development of medical countermeasures for use in the event of a radiation public health emergency. These efforts can now be leveraged to help elucidate mechanisms of action of COVID-19 injuries. Furthermore, this intersection between COVID-19 and ARS may point to approaches that could accelerate the discovery of treatments for both.

Protective Effects of IMOD and Cimetidine against Radiation-induced Cellular Damage

Radiation damage is to a large extent caused by overproduction of reactive oxygen species (ROS). Radioprotectors are agents or substances that reduce the effects of radiation in healthy normal tissues while maintaining the sensitivity to radiation damage in tumor cells. Radioprotectors are agents or substances that reduce the effects of radiation in healthy normal tissues while maintaining the sensitivity to radiation damage in tumor cells Cimetidine was found more effective when used in vivo; this effect might be due to the augmentation of the presence of Sulphur atom in the compound which is ýimportant for their scavenging activity. Recently, a new herbal-based medicine with immunomodulatory capacities, Setarud (IMOD), was introduced as an additional therapy in various inflammatory diseases and HIV infection. IMOD is a mixture of herbal extracts enriched with selenium. Selenium confers protection by inducing or activating cellular free-radical scavenging systems and by enhancing peroxide breakdown. This article suggests that nontoxic amount of IMOD and cimetidine have radioprotective properties and could reduce cytotoxic effects of radiation.

Oral Administration of Vitamin C, Cimetidine and Famotidine on Micronuclei Induced by Low Dose Radiation in Mouse Bone Marrow Cells

BACKGROUND

In many studies, chemicals and natural materials were tested to reduce the harmful effects of radiation. It is known that Famotidine and vitamin C reduce DNA damage.

OBJECTIVE

The aim of this study was to evaluate the radioprotective effect of vitamin C, Cimetidine and Famotidine on gamma-radiation-induced damage on mouse bone marrow.

METHODS

Six-to-seven week male NMRI mice (28 g ±3) were randomly divided into fourteen groups: control, 2Gy irradiation, six group drugs without irradition (Famotidine, Cimetidine, vitaminC, Fam-Cim, Fam-Vit, Cim-Vit), six groups received drugs and 2Gy radiation with a 60Co |γ|-ray source at room temperature 22 ± 2 °C. The mice were killed 48 hours after irradiation by cervical dislocation. Slides were prepared from bone marrow cells and stained in May-Granwald and Giemsa. Finally, the cells were counted with microscope, frequencies of polychromatic erythrocyte (PCE), normochoromatic erythrocyte (NCE) and their micronuclated cell were recorded. PCE / PCE + NCE were calculated.

RESULTS

There were significant differences of MNPCE/1000PCE, MNNCE/1000NCE and PCE/PCE+NCE among different groups with similar radiation doses (p≤0.01). Moreover, there were significant differences of MNPCE/1000PCE and PCE/PCE+NCE among different doses of radiation (p≤0.01). While considering MNNCE/1000NCE, there were no significant differences among silimar groups with radiation dose (p˃0.05).

CONCLUSION

Oral administration of Famotidine, vitamin C and Cimetidine demonstrate reliable and similar radioprotective effects. Additionally, the protective effect of single use of these drugs was similar to the combination form. Thus, the oral use of combination, 48 hours after irradiation cannot induce more radioprotective effect.

Radioprotective effect of Zamzam (alkaline) water: A cytogenetic study

BACKGROUND

Radioprotectors are useful compounds to reduce radiation toxicity of normal cells. Many natural radioprotectors have antioxidant power and display fewer toxicity and side effects than the chemical ones. Alkaline waters such as Zamzam have antioxidant power potentially. This study aimed to investigate the radioprotective effect of Zamzam water in mice bone marrow exposed to gamma radiation by micronuclei test.

METHOD

Five study groups including control group which was fed by ordinary water, the second group was fed by Zamzam water, and radiation groups were received 2Gy gamma with ordinary and Zamzam water for 10 days and another for 20 days. The frequency of micronuclei and polychromatic erythrocytes to normochromatic erythrocytes ratio were calculated by micronuclei test.

RESULT

In the absence of radiation, no significant difference was found between Zamzam group and control in the number of micronuclei in normochromatic erythrocytes, micronuclei in polychromatic erythrocytes, and the polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte ratio. But all of these indices were significantly different between irradiated and non-irradiated groups. The frequency of micronuclei in polychromatic erythrocytes was not significantly different between 10 and 20 days Zamzam irradiated groups, but the reduction in micronuclei in normochromatic erythrocytes and an increase in the polychromatic erythrocyte to polychromatic erythrocyte plus normochromatic erythrocyte ratio compared to ordinary water were seen in 20 days Zamzam group. Dose reduction factor was 1.36 and 2 for Zamzam water groups of 10 days and 20 days, respectively.

CONCLUSION

The results demonstrated that Zamzam alkaline water could reduce clastogenic and cytotoxic effects of gamma irradiation.

Potent radioprotective effects of combined regimens of famotidine and vitamin C against radiation-induced micronuclei in mouse bone marrow erythrocytes

To investigate the radioprotective effect of the combination of famotidine and vitamin C against radiation-induced micronucleus formation in mouse bone marrow erythrocytes, various doses of famotidine or vitamin C or combinations thereof were administered intraperitoneally to adult male NMRI mice 2 h before 2 and 4 Gy γ-irradiation. The frequency of micronucleated polychromatic erythrocytes (MnPCEs) was scored in 5,000 polychromatic erythrocytes (PCEs), and the cell proliferation ratio [PCE/(PCE + NCE); NCE = normochromatic erythrocytes] was also calculated for each treatment group. Data were statistically evaluated using one-way ANOVA test. The results show that pretreatment with various doses of famotidine and vitamin C before γ-irradiation significantly reduced the frequency of MnPCEs with a protection factor (PF) of 2 and 1.7, respectively. Pretreatment with vitamin C also significantly increased the cell proliferation ratio, while famotidine had no effect. Combination of famotidine and vitamin C was more effective in reducing MnPCEs than each compound alone, leading to a PF of 4.3 after irradiation. Cell proliferation ratio was also significantly improved by the combination compared with the irradiated control groups. Both famotidine and vitamin C are potent scavengers of free radicals and reactive oxygen species, especially OH(·). The combination of the two compounds probably further enhances this activity, thus leading to high bone marrow protection.

Famotidine as a radioprotector for rectal mucosa in prostate cancer patients treated with radiotherapy: phase I/II randomized placebo-controlled trial

BACKGROUND AND PURPOSE

Acute bowel toxicity significantly affects the quality of life of patients treated with pelvic radiotherapy. This study was performed to assess whether pretreatment with famotidine can reduce acute radiation toxicities in patients undergoing radiotherapy for prostate cancer.

PATIENTS AND METHODS

Between April 2012 and February 2013, 36 patients undergoing radiotherapy for prostate cancer were enrolled to receive either placebo or famotidine. The patients received external-beam radiotherapy up to 70 Gy at daily fractions of 1.8-2 Gy (5 days/week). Oral famotidine 40 mg (80 mg/day) or placebo was administered twice daily (4 and 3 h prior to each radiotherapy fraction). Bowel and bladder acute toxicities were evaluated weekly during radiotherapy and once thereafter according to RTOG grading criteria.

RESULTS

Famotidine was well tolerated. No grade III or higher acute toxicities were noted in the two groups. Grade II rectal toxicity developed significantly more often in patients receiving placebo than in patients receiving famotidine (10/18 vs. 2/16, p=0.009). Moreover, no rectal bleeding occurred in the famotidine group, while 5 patients in the placebo group experienced rectal bleeding during treatment (p=0.046). The duration of rectal toxicity in the radiotherapy course was also reduced in the famotidine group (15.7 vs. 25.2 days, p=0.027). No significant difference between the two groups was observed in terms of urinary toxicity.

CONCLUSION

We demonstrated for the first time that famotidine significantly reduces radiation-induced injury on rectal mucosa representing a suitable radioprotector for patients treated with radiotherapy for prostate cancer.

Evaluation of the comet assay for assessing the dose-response relationship of DNA damage induced by ionizing radiation

Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001). A time-response relationship was also found within 72 h after irradiation (p < 0.001). The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined.

Effect of radiation treatment on newly established human breast cancer cell lines MACL-1 and MGSO-3

The characterization of new cell lines is an important tool to understand the biological processes involved in cancer treatments. In the present study, we used two newly established epithelial human breast cancer cell lines from primary sites MACL-1 and MGSO-3 and compared their susceptibility to the treatment with ionizing radiation (IR) with the commercial cell line MDA-MB-231. In the doses used (10 or 20 Gy), IR induced a reduction in cell viability and cell death, measured as DNA fragmentation, at 48 and 72 h after treatment. In addition, 48 h after treatment with IR, we observed an enhancement in the percentage of apoptotic cells. The broad-range caspases inhibitor zVAD-FMK inhibited cytotoxicity induced by IR. After 24 h, treatment with IR activated caspase-9 in MACL-1 and MDA-MB-231 but not in MGSO-3 cells. Thirty hours after treatment with IR (20 Gy), we observed an activation of caspases 8 and 3. These results suggest the involvement of caspases in the cell death induced by IR in two newly established cell lines. These cells may be useful in studies of breast cancer in defining basic mechanisms in molecular and cellular radiobiology and may contribute to the rational design of future models of cancer therapies.

Radiation sensitivity of leukocytes from healthy individuals and breast cancer patients as measured by the alkaline and neutral comet assay

Initial radiation-induced DNA damage, dose-response curves and kinetics of DNA repair in leukocytes from healthy volunteers and breast cancer patients, was assessed using alkaline and neutral comet assay after exposure to (60)Co gamma rays. Both versions of comet assay showed higher levels of baseline DNA damage in leukocytes of breast cancer cases than in controls. Gamma ray induced initial DNA damage in leukocytes of cancer cases was not significantly different from that of healthy donors. A similar dose-response was obtained with both versions of comets for two groups. After a repair time of 24h, following irradiation, samples from the healthy individuals showed no residual DNA damage in their leukocytes, whereas breast cancer patients revealed more than 20%. Although similar initial radiosensitivity was observed for both groups but the repair kinetics of radiation-induced DNA damage of leukocytes from breast cancer cases and healthy subjects was statistically different.

Modulation of gamma-ray-induced apoptosis in human peripheral blood leukocytes by famotidine and vitamin C

To study the radioprotective effects of vitamin C and famotidine against radiation-induced apoptosis in human peripheral blood leukocytes, peripheral blood was obtained from six healthy volunteers including three males and three females. Twelve microlitres of blood sample diluted in 1 ml complete RPMI-1640 medium was irradiated with various doses of gamma-rays (4, 8 and 12 Gy) in the presence or absence of various doses of vitamin C and famotidine. After 48 and 72 h incubation in a 37 degrees C CO(2) incubator, neutral comet assay was performed for all samples. At least 1000 cells were analyzed for each sample for presence of apoptosis. Data were statistically evaluated using Mann-Whitney non-parametric and ANOVA tests. Results show a significant increase in apoptosis induction following gamma-irradiation with a dose dependent manner compared to controls (p<0.001). Presence of famotidine at 200 microg/ml produced a significant protective effect against radiation-induced apoptosis for various doses of radiation. Similar effects were observed for vitamin C at much lower doses (10 microg/ml). Dose reduction factor (DRF) calculated for famotidine treatment was about 1.5, and above 2 for vitamin C treatment. These results suggest that both vitamin C and famotidine suppresses radiation-induced apoptosis when used with various doses of gamma-irradiation (4-12 Gy) probably via *OH radical scavenging and an intracellular antioxidation mechanism.