Radiation injury to cardiac arteries and myocardium is reduced by soy isoflavones

Polyphenols as Potential Protectors against Radiation-Induced Adverse Effects in Patients with Thoracic Cancer

Radiotherapy is one of the standard treatment approaches used against thoracic cancers, occasionally combined with chemotherapy, immunotherapy and molecular targeted therapy. However, these cancers are often not highly sensitive to standard of care treatments, making the use of high dose radiotherapy necessary, which is linked with high rates of radiation-induced adverse effects in healthy tissues of the thorax. These tissues remain therefore dose-limiting factors in radiation oncology despite recent technological advances in treatment planning and delivery of irradiation. Polyphenols are metabolites found in plants that have been suggested to improve the therapeutic window by sensitizing the tumor to radiotherapy, while simultaneously protecting normal cells from therapy-induced damage by preventing DNA damage, as well as having anti-oxidant, anti-inflammatory or immunomodulatory properties. This review focuses on the radioprotective effect of polyphenols and the molecular mechanisms underlying these effects in the normal tissue, especially in the lung, heart and esophagus.

Murine models of radiation cardiotoxicity: A systematic review and recommendations for future studies

BACKGROUND AND PURPOSE

The effects of radiation on the heart are dependent on dose, fractionation, overall treatment time, and pre-existing cardiovascular pathology. Murine models have played a central role in improving our understanding of the radiation response of the heart yet a wide range of exposure parameters have been used. We evaluated the study design of published murine cardiac irradiation experiments to assess gaps in the literature and to suggest guidance for the harmonisation of future study reporting.

METHODS AND MATERIALS

A systematic review of mouse/rat studies published 1981-2021 that examined the effect of radiation on the heart was performed. The protocol was published on PROSPERO (CRD42021238921) and the findings were reported in accordance with the PRISMA guidance. Risk of bias was assessed using the SYRCLE checklist.

RESULTS

159 relevant full-text original articles were reviewed. The heart only was the target volume in 67% of the studies and simulation details were unavailable for 44% studies. Dosimetry methods were reported in 31% studies. The pulmonary effects of whole and partial heart irradiation were reported in 13% studies. Seventy-eight unique dose-fractionation schedules were evaluated. Large heterogeneity was observed in the endpoints measured, and the reporting standards were highly variable.

CONCLUSIONS

Current murine models of radiation cardiotoxicity cover a wide range of irradiation configurations and latency periods. There is a lack of evidence describing clinically relevant dose-fractionations, circulating biomarkers and radioprotectants. Recommendations for the consistent reporting of methods and results of in vivo cardiac irradiation studies are made to increase their suitability for informing the design of clinical studies.

Hesperidin Modulates Troponin-1 Serum Level and Decrease Heart Tissue Injury of Irradiated Rats

BACKGROUND

The heart is the major dose-limiting organ for radiotherapy of malignant tumor in the mediastanal region.

OBJECTIVE

This study aims to investigate the radio protective effects of Hesperidin (HES) as a natural flavonoid after localized irradiation of the rat's mediastinum region.

MATERIAL AND METHODS

In this experimental study, we divided sixty male rats into 4 groups (n=15). First group: Sham which received PBS; second group: Hesperidin only (100 mg/kg/day orally) for one week; third group: Radiation that received single dose of 20 Gy gamma radiation using Co-60 unit and the forth group: Radiation+HES that underwent the same dose of radiation and received HES for 7 days prior irradiation. Each group was divided in two branches. Early sampling from subgroup one was done 4-6 hours after irradiation to determine troponin-1 level changes. Rats of second subgroups were killed 56 days after irradiation for histopathological evidence.

RESULTS

In radiation group, troponin -1 serum level had a significant increase in comparison with sham group (P<0.05). Histopathological evaluation of second subgroup showed there was a significant difference between sham and radiation group in some parameters. Inflammation (p=0.008), pericardial effusion (P=0.001), and vascular plaque (P=0.001) had an increase in the irradiation group. Oral administration of hesperidin significantly decreased all the above factors when was compared with irradiation group (P>0.016).

CONCLUSION

Oral administration of Hesperidine for seven days prior radiotherapy may decrease troponin-1 and cardiac injury due to radiation.

Isoflavone-mediated radioprotection involves regulation of early endothelial cell death and inflammatory signaling in Radiation-Induced lung injury

Purpose: Vascular damage and inflammation are limiting toxic effects of lung cancer radiotherapy, which lead to pneumonitis and pulmonary fibrosis. We have demonstrated that soy isoflavones (SIF) mitigate these toxic effects at late time points after radiation. However, the process by which SIF impacts the onset of radiation-induced inflammation remains to be elucidated. We have now investigated early events of radiation-induced inflammation and identified cellular and molecular signaling patterns by endothelial cells that could be modified by SIF to control vascular damage and the initiation of lung inflammation.Materials and methods: Histopathological, cellular and molecular studies were performed on mouse lungs from C57Bl/6 mice treated with 10 Gy of thoracic radiation (XRT) in conjunction with daily oral SIF treatment given prior and after radiation. Parallel studies were performed in-vitro using EA.hy926 endothelial cell line with SIF and radiation. Immunohistochemistry, western blots analysis, and flow cytometry were performed on lung tissue or EA.hy926 cells to analyze endothelial cells, their patterns of cell death or survival, and signaling molecules involved in inflammatory events.Results: Histopathological differences in inflammatory infiltrates and vascular injury in lungs, including vascular endothelial cells, were observed with SIF treatment at early time points post-XRT. XRT-induced expression of proinflammatory adhesion molecule ICAM-1 cells was reduced by SIF in-vitro and in-vivo in endothelial cells. Molecular changes in endothelial cells with SIF treatment in conjunction with XRT included increased DNA damage, reduced cell viability and cyclin B1, and inhibition of nuclear translocation of NF-κB. Analysis of cell death showed that SIF treatment promoted apoptotic endothelial cell death and decreased XRT-induced type III cell death. In-vitro molecular studies indicated that SIF + XRT increased apoptotic caspase-9 activation and production of IFNβ while reducing the release of inflammatory HMGB-1 and IL-1α, the cleavage of pyroptotic gasdermin D, and the release of active IL-1β, which are all events associated with type III cell death.Conclusions: SIF + XRT caused changes in patterns of endothelial cell death and survival, proinflammatory molecule release, and adhesion molecule expression at early time points post-XRT associated with early reduction of immune cell recruitment. These findings suggest that SIF could mediate its radioprotective effects in irradiated lungs by limiting excessive immune cell homing via vascular endothelium into damaged lung tissue and curtailing the overall inflammatory response to radiation.

Soy Isoflavones Protect Normal Tissues While Enhancing Radiation Responses

Soy isoflavones have demonstrated chemopreventive and anticancer properties in epidemiology and biological studies, in addition to their function as antioxidants in prevention of cardiovascular disease. We have explored the potential of soy isoflavones, as a safe biological approach, to enhance the efficacy of radiotherapy for local tumor control and limit normal tissue damage in solid tumors. This review presents studies investigating the interaction between soy isoflavones and radiation in different malignancies, including prostate cancer, renal cell carcinoma, and nonsmall cell lung cancer. Soy isoflavones were found to be potent sensitizers of cancer cells to radiation causing increased cell killing in vitro in human tumor cell lines and greater tumor inhibition in vivo in preclinical orthotopic murine tumor models. In the course of these studies, radioprotection of normal tissues and organs in the field of radiation was observed both in a clinical trial for prostate cancer and in preclinical models. The mechanisms of radiosensitization and radioprotection mediated by soy isoflavones are discussed and emphasize the role of soy isoflavones in increasing radiation effect on tumor and mitigating inflammatory responses induced by radiation in normal tissues. Soy isoflavones could be used as a safe, nontoxic complementary strategy that simultaneously increases radiation effectiveness on the malignancy while reducing damage in normal tissues in the field of radiation.