Analysis of the mechanism of radiation-induced upregulation of mitochondrial abundance in mouse fibroblasts

Use of 3D printing technology for custom bolus fabrication in the management of palmar or plantar fibromatosis with radiotherapy: A retrospective case series

PURPOSE

Palmar or plantar fibromatosis is a benign fibroproliferative disorder affecting the fascia of the hands or feet. Management involves surgery, typically reserved for cases where progression limits function. Retrospective series demonstrate that radiation therapy (RT) can stabilize the disease course in many patients and improve symptoms in some cases. RT techniques vary between the use of electrons and superficial or orthovoltage photons and often require lead cutouts or custom boluses. We present a new approach demonstrating the implementation and effectiveness of three-dimensional (3D)-printed bolus material in patients receiving RT for fibromatosis.

MATERIALS AND METHODS

A total of 3 patients, one with plantar and two with palmar fibromatosis, were treated with radiation using 3D-printed boluses over the past year. Bolus's design was based on computed tomography (CT) imaging data. Palmar patients were treated with a single en-face electron field, with a two-part accessory as a bolus and an immobilization device encasing the hand. The plantar case required 6MV photons delivered with a Volumetric Modulated Arc Therapy (VMAT) technique to cover the deeper target volume adequately. Dose and fractionation were based on guidelines from the Royal College of Radiologists in the United Kingdom. CT was used to assess printed shape and density accuracy.

RESULTS

The mean deviations in shape between the printed bolus pieces and their designs were all less than 0.4 mm. The differences in mean Hounsefield units (HU) between the printed boluses and their expected values were between 7 and 44 HU. No significant issues were encountered when applying the bolus to patients. The thermoluminescent dosimeters (TLD) used demonstrated dose accuracy to within TLD precision (5 %).

CONCLUSIONS

3D printing bolus technology represents a novel approach to treating fibromatosis with radiation. It offers superior dosimetry through the reduction of air gaps and by permitting custom bolus thickness. Also, it simplifies clinical set-up by acting as an immobilization device and a visual aid for daily field placement.

Heme Biosynthesis is Crucial for Cell Survival and Mitochondrial OXPHOS after X Irradiation

Heme is an essential component of the hemoproteins involved in the mitochondrial electron transport chain (ETC). Cancer cells have been reported to display high heme levels and increased activity of heme-containing proteins. Consistently, inhibition of heme biosynthesis by the ALAD inhibitor succinylacetone (SA) has been shown to reduce tumor cell survival. These observations indicate that heme biosynthesis is essential for cancer cell proliferation. X irradiation has been shown to increase mitochondrial mass, membrane potential, oxygen consumption, reactive oxygen species (ROS) production, and ATP synthesis. This finding suggests that radiation activates mitochondrial oxidative phosphorylation (OXPHOS). However, although heme is an essential component of the mitochondrial ETC, whether radiation influences heme biosynthesis remains unclear. In this study, we evaluated heme biosynthesis activity after X irradiation and examined the effects of heme biosynthesis inhibition by SA on cellular radiosensitivity and mitochondrial OXPHOS function. We demonstrated that X irradiation significantly increased ALAS1 mRNA levels and cellular heme content. Inhibition of heme biosynthesis by SA significantly decreased cellular heme content and sensitized cancer cells to radiation. We also showed that SA reduced cellular ATP levels, mitochondrial membrane potential, and mitochondrial ROS production, suggesting mitochondrial OXPHOS dysfunction. SA decreased the expression of mitochondrial heme-related proteins COX2 and cytochrome c but did not influence COX1 and VDAC expression. These results indicate that inhibition of heme biosynthesis decreased mitochondrial ETC protein expression and OXPHOS activity, which triggered cellular ATP depletion and radiosensitization after X irradiation. In summary, heme biosynthesis is upregulated by X irradiation and is essential for mitochondrial OXPHOS and cell survival.

Roles of mitochondrial fusion and fission in breast cancer progression: a systematic review

Background

Mitochondria play critical roles in cellular physiological activity as cellular organelles. Under extracellular stimulation, mitochondria undergo constant fusion and fission to meet different cellular demands. Mitochondrial dynamics, which are involved in mitochondrial fusion and fission, are regulated by specialized proteins and lipids, and their dysregulation causes human diseases, such as cancer. The advanced literature about the crucial role of mitochondrial dynamics in breast cancer is performed.

Methods

All related studies were systematically searched through online databases (PubMed, Web of Science, and EMBASE) using keywords (e.g., breast cancer, mitochondrial, fission, and fusion), and these studies were then screened through the preset inclusion and exclusion criteria.

Results

Eligible studies (n = 19) were evaluated and discussed in the systematic review. These advanced studies established the roles of mitochondrial fission and fusion of breast cancer in the metabolism, proliferation, survival, and metastasis. Importantly, the manipulating of mitochondrial dynamic is significant for the progresses of breast cancer.

Conclusion

Understanding the mechanisms underlying mitochondrial fission and fusion during tumorigenesis is important for improving breast cancer treatments.

Radioprotective and Radiomitigative Effects of Melatonin in Tissues with Different Proliferative Activity

We used various markers to analyze damage to mouse tissues (spleen and cerebral cortex) which have different proliferative activity and sensitivity to ionizing radiation (IR). We also assessed the degree of modulation of damages that occurs when melatonin is administered to mice prior to and after their X-ray irradiation. The data from this study showed that lesions in nuclear DNA (nDNA) were repaired more actively in the spleen than in the cerebral cortex of mice irradiated and treated with melatonin (N-acetyl-5-methoxytryptamine). Mitochondrial biogenesis involving mitochondrial DNA (mtDNA) synthesis was activated in both tissues of irradiated mice. A significant proportion of the newly synthesized mtDNA molecules were mutant copies that increase oxidative stress. Melatonin reduced the number of mutant mtDNA copies and the level of H2O2 in both tissues of the irradiated mice. Melatonin promoted the restoration of ATP levels in the tissues of irradiated mice. In the mouse tissues after exposure to X-ray, the level of malondialdehyde (MDA) increased and melatonin was able to reduce it. The MDA concentration was higher in the cerebral cortex tissue than that in the spleen tissue of the mouse. In mouse tissues following irradiation, the glutathione (GSH) level was low. The spleen GSH content was more than twice as low as that in the cerebral cortex. Melatonin helped restore the GSH levels in the mouse tissues. Although the spleen and cerebral cortex tissues of mice differ in the baseline values of the analyzed markers, the radioprotective and radiomitigative potential of melatonin was observed in both tissues.

Combined metformin-salicylate treatment provides improved anti-tumor activity and enhanced radiotherapy response in prostate cancer; drug synergy at clinically relevant doses

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Combined metformin + salicylate treatment has improved anti-tumor efficacy in prostate cancer.

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At clinically achievable doses, it induces increased metabolic stress and sensitizes tumors to radiation.

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Metformin + salicylate blocks pathways of de novo lipogenesis and protein synthesis.

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In combination with radiation suppresses HIF1a and DNA replication.

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This work supports clinical investigation of metformin + salicylate in combination with radiotherapy.

Background

There is need for well-tolerated therapies for prostate cancer (PrCa) secondary prevention and to improve response to radiotherapy (RT). The anti-diabetic agent metformin (MET) and the aspirin metabolite salicylate (SAL) are shown to activate AMP-activated protein kinase (AMPK), suppress de novo lipogenesis (DNL), the mammalian target of rapamycin (mTOR) pathway and reduce PrCa proliferation in-vitro. The purpose of this study was to examine whether combined MET+SAL treatment could provide enhanced PrCa tumor suppression and improve response to RT.

Methods

Androgen-sensitive (22RV1) and resistant (PC3, DU-145) PrCa cells and PC3 xenografts were used to examine whether combined treatment with MET+SAL can provide improved anti-tumor activity compared to each agent alone in non-irradiated and irradiated PrCa cells and tumors. Mechanisms of action were investigated with analysis of signaling events, mitochondria respiration and DNL activity assays.

Results

We observed that PrCa cells are resistant to clinically relevant doses of MET. Combined MET + SAL treatment provides synergistic anti-proliferative activity at clinically relevant doses and enhances the anti-proliferative effects of RT. This was associated with suppression of oxygen consumption rate (OCR), activation of AMPK, suppression of acetyl-CoA carboxylase (ACC)-DNL and mTOR-p70^s6k/4EBP1 and HIF1α pathways. MET + SAL reduced tumor growth in non-irradiated tumors and enhanced the effects of RT.

Conclusion

MET+SAL treatment suppresses PrCa cell proliferation and tumor growth and enhances responses to RT at clinically relevant doses. Since MET and SAL are safe, widely-used and inexpensive agents, these data support the investigation of MET+SAL in PrCa clinical trials alone and in combination with RT.

Role of Commensal Microbes in the γ-Ray Irradiation-Induced Physiological Changes in Drosophila melanogaster

Ionizing radiation induces biological/physiological changes and affects commensal microbes, but few studies have examined the relationship between the physiological changes induced by irradiation and commensal microbes. This study investigated the role of commensal microbes in the γ-ray irradiation-induced physiological changes in Drosophila melanogaster. The bacterial load was increased in 5 Gy irradiated flies, but irradiation decreased the number of operational taxonomic units. The mean lifespan of conventional flies showed no significant change by irradiation, whereas that of axenic flies was negatively correlated with the radiation dose. γ-Ray irradiation did not change the average number of eggs in both conventional and axenic flies. Locomotion of conventional flies was decreased after 5 Gy radiation exposure, whereas no significant change in locomotion activity was detected in axenic flies after irradiation. γ-Ray irradiation increased the generation of reactive oxygen species in both conventional and axenic flies, but the increase was higher in axenic flies. Similarly, the amounts of mitochondria were increased in irradiated axenic flies but not in conventional flies. These results suggest that axenic flies are more sensitive in their mitochondrial responses to radiation than conventional flies, and increased sensitivity leads to a reduced lifespan and other physiological changes in axenic flies.

Low mitochondrial DNA copy number is associated with poor prognosis and treatment resistance in glioblastoma

INTRODUCTION

Mitochondrial DNA (mtDNA) content in several solid tumors was found to be lower than in their normal counterparts. However, there is paucity of literature on the clinical significance of mtDNA content in glioblastoma and its effect on treatment response. Hence, we studied the prognostic significance of mtDNA content in glioblastoma tumor tissue and the effect of mtDNA depletion in glioblastoma cells on response to treatment.

MATERIALS AND METHODS

130 newly diagnosed glioblastomas, 32 paired newly diagnosed and recurrent glioblastomas and 35 non-neoplastic brain tissues were utilized for the study. mtDNA content in the patient tumor tissue was assessed and compared with known biomarkers and patient survival. mtDNA was chemically depleted in malignant glioma cell lines, U87, LN229. The biology and treatment response of parent and depleted cells were compared.

RESULTS

Lower range of mtDNA copy number in glioblastoma was associated with poor overall survival (p = 0.01), progression free survival (p = 0.04) and also with wild type IDH (p = 0.02). In recurrent glioblastoma, mtDNA copy number was higher than newly diagnosed glioblastoma in the patients who received RT (p = 0.01). mtDNA depleted U87 and LN229 cells showed higher survival fraction post radiation exposure when compared to parent lines. The IC50 of TMZ was also higher for mtDNA depleted U87 and LN229 cells. The depleted cells formed more neurospheres than their parent counterparts, thus showing increased stemness of mtDNA depleted cells.

CONCLUSION

Low mtDNA copy number in glioblastoma is associated with poor patient survival and treatment resistance in cell lines possibly by impacting stemness of the glioblastoma cells.

Reprint of: Deciphering and simulating models of radiation genotoxicity with CRISPR/Cas9 systems

This short review explores the utility and applications of CRISPR/Cas9 systems in radiobiology. Specifically, in the context of experimentally simulating genotoxic effects of Ionizing Radiation (IR) to determine the contributions from DNA targets and 'Complex Double-Stranded Breaks' (complex DSBs) to the IR response. To elucidate this objective, this review considers applications of CRISPR/Cas9 on nuclear DNA targets to recognize the respective 'nucleocentric' response. The article also highlights contributions from mitochondrial DNA (mtDNA) - an often under-recognized target in radiobiology. This objective requires accurate experimental simulation of IR-like effects and parameters with the CRISPR/Cas9 systems. Therefore, the role of anti-CRISPR proteins in modulating enzyme activity to simulate dose rate - an important factor in radiobiology experiments is an important topic of this review. The applications of auxiliary domains on the Cas9 nuclease to simulate oxidative base damage and multiple stressor experiments are also topics of discussion. Ultimately, incorporation of CRISPR/Cas9 experiments into computational parameters in radiobiology models of IR damage and shortcomings to the technology are discussed as well. Altogether, the simulation of IR parameters and lack of damage to non-DNA targets in the CRISPR/Cas9 system lends this rapidly emerging tool as an effective model of IR induced DNA damage. Therefore, this literature review ultimately considers the relevance of complex DSBs to radiobiology with respect to using the CRISPR/Cas9 system as an effective experimental tool in models of IR induced effects.

Stimulation of cytoprotective autophagy and components of mitochondrial biogenesis / proteostasis in response to ionizing radiation as a credible pro-survival strategy

The present study illustrates mitochondria-mediated impact of ionizing radiation which is paralleled by activation of several pro-adaptive responses in normal human dermal fibroblast cells. Irradiation of cells with X-rays (5 Gy) led to an increase in fragmentation and mitochondrial mass. Distinct temporal changes in cytosolic and mitochondrial reactive oxygen species (ROS) were noted in response to radiation, which was associated with depletion in mitochondrial membrane potential followed by decrease in ATP levels. Long Amplicon-Polymerase Chain Reaction (LA-PCR) analysis showed time-dependent increase in mitochondrial DNA damage that preceded mitochondrial ROS generation. Irradiation of cells led to an initial G₂/M arrest at 8 h that persisted till 16 h, with subsequent block at G₀/G₁ measured at 48 and 72 h time points. Interestingly, cells activated autophagy as a countermeasure against radiation-mediated cellular insults and aided in removal of damaged mitochondria. Blocking autophagy using 3-methyladenine led to cell death via activation of enhanced ROS, PARP-1 and caspase 3 cleavage. Upregulation of mitochondrial biogenesis factors Nrf1/PGC-1α, following irradiation was observed. Irradiated cells exhibited an increase in the phosphorylation of GCN2, PERK and eIF2α that might be responsible for the up-regulation of ATF4 and CHOP thereby regulating autophagy and components of integrated stress response. Apart from this, we measured accumulation of mitochondrial chaperones (HSP60/HSP10) and ATF5 which is a major molecule involved in mitochondrial stress. Taken together, mitochondria are one of the major cytoplasmic targets for ionizing radiation and possibly act as an early indicator of cellular insult. The findings also show that stressed mitochondria might influence endoplasmic reticulum (ER)-related signalling leading to the activation of adaptive mechanisms like cytoprotective autophagy, and molecules responsible for mitochondrial biogenesis and protein quality control in order to replenish mitochondrial pool and maintain cellular homeostasis.

Deciphering and simulating models of radiation genotoxicity with CRISPR/Cas9 systems

This short review explores the utility and applications of CRISPR/Cas9 systems in radiobiology. Specifically, in the context of experimentally simulating genotoxic effects of Ionizing Radiation (IR) to determine the contributions from DNA targets and 'Complex Double-Stranded Breaks' (complex DSBs) to the IR response. To elucidate this objective, this review considers applications of CRISPR/Cas9 on nuclear DNA targets to recognize the respective 'nucleocentric' response. The article also highlights contributions from mitochondrial DNA (mtDNA) - an often under-recognized target in radiobiology. This objective requires accurate experimental simulation of IR-like effects and parameters with the CRISPR/Cas9 systems. Therefore, the role of anti-CRISPR proteins in modulating enzyme activity to simulate dose rate - an important factor in radiobiology experiments is an important topic of this review. The applications of auxiliary domains on the Cas9 nuclease to simulate oxidative base damage and multiple stressor experiments are also topics of discussion. Ultimately, incorporation of CRISPR/Cas9 experiments into computational parameters in radiobiology models of IR damage and shortcomings to the technology are discussed as well. Altogether, the simulation of IR parameters and lack of damage to non-DNA targets in the CRISPR/Cas9 system lends this rapidly emerging tool as an effective model of IR induced DNA damage. Therefore, this literature review ultimately considers the relevance of complex DSBs to radiobiology with respect to using the CRISPR/Cas9 system as an effective experimental tool in models of IR induced effects.

Increase of mtDNA number and its mutant copies in rat brain after exposure to 150 MeV protons

Proton beam therapy is widely used for treating brain tumor. Despite the efficacy of treatment, the use of this therapy has met some limitations associated with possible damage to normal brain tissues located beyond the tumor site. In this context, the exploration of the harmful effects of protons on the normal brain tissues is of particular interest. We have investigated changes in the total mitochondrial DNA (mtDNA) copy number and identified mtDNA mutant copies in three brain regions (the hippocampus, cortex and cerebellum) of rats after irradiation their whole-head with 150 MeV protons at doses of 3 and 5 Gy. The study was performed in 2-months old male Spraque Dawley rats (n = 5 each group). The mtDNA copy numbers were determined by real-time PCR. The level of mtDNA heteroplasmy was estimated using Surveyor nuclease technology. Our results show that after head exposure to protons, levels of mtDNA copy number in three rat brain regions increase significantly as the levels of mtDNA mutant copies increase. The most significant elevation is observed in the hippocampus. In conclusion, an increase in mtDNA mutant copies may contribute to mitochondrial dysfunction accompanied by increased oxidative stress in different brain regions and promote the development of neurodegenerative diseases and the induction of carcinogenesis.

Elevated HDAC activity and altered histone phospho-acetylation confer acquired radio-resistant phenotype to breast cancer cells

Background

Poor-responsiveness of tumors to radiotherapy is a major clinical problem. Owing to the dynamic nature of the epigenome, the identification and targeting of potential epigenetic modifiers may be helpful to curb radio-resistance. This requires a detailed exploration of the epigenetic changes that occur during the acquirement of radio-resistance. Such an understanding can be applied for effective utilization of treatment adjuncts to enhance the efficacy of radiotherapy and reduce the incidence of tumor recurrence.

Results

This study explored the epigenetic alterations that occur during the acquirement of radio-resistance. Sequential irradiation of MCF7 breast cancer cell line up to 20 Gy generated a radio-resistant model. Micrococcal nuclease digestion demonstrated the presence of compact chromatin architecture coupled with decreased levels of histone PTMs H3K9ac, H3K27 ac, and H3S10pK14ac in the G₀/G₁ and mitotic cell cycle phases of the radio-resistant cells. Further investigation revealed that the radio-resistant population possessed high HDAC and low HAT activity, thus making them suitable candidates for HDAC inhibitor–based radio-sensitization. Treatment of radio-resistant cells with HDAC inhibitor valproic acid led to the retention of γH2AX and decreased H3S10p after irradiation. Additionally, an analysis of 38 human patient samples obtained from 8 different tumor types showed variable tumor HDAC activity, thus demonstrating inter-tumoral epigenetic heterogeneity in a patient population.

Conclusion

The study revealed that an imbalance of HAT and HDAC activities led to the loss of site-specific histone acetylation and chromatin compaction as breast cancer cells acquired radio-resistance. Due to variation in the tumor HDAC activity among patients, our report suggests performing a prior assessment of the tumor epigenome to maximize the benefit of HDAC inhibitor–based radio-sensitization.

Graphical abstract

Mitochondrial fission promotes radiation-induced increase in intracellular Ca2+ level leading to mitotic catastrophe in mouse breast cancer EMT6 cells

Mitochondrial dynamics are crucial for cellular survival in response to various stresses. Previously, we reported that Drp1 promoted mitochondrial fission after x-irradiation and its inhibition resulted in reduced cellular radiosensitivity and mitotic catastrophe. However, the mechanisms of radiation-induced mitotic catastrophe related to mitochondrial fission remain unclear. In this study, we investigated the involvement of cellular ATP production, ROS generation, and Ca²⁺ levels in mitotic catastrophe in EMT6 cells. Knockdown of Drp1 and Fis1, which are mitochondrial fission regulators, resulted in elongated mitochondria and significantly attenuated cellular radiosensitivity. Reduced mitochondrial fission mainly decreased mitotic catastrophe rather than necrosis and apoptosis after irradiation. Cellular ATP contents in Drp1 and Fis1 knockdown cells were similar to those in control cells. N-acetylcysteine and 2-glucopyranoside ascorbic acid have no effect on mitotic catastrophe after irradiation. The cellular [Ca²⁺]i level increased after irradiation, which was completely suppressed by Drp1 and Fis1 inhibition. Furthermore, BAPTA-AM significantly reduced radiation-induced mitotic catastrophe, indicating that cellular Ca²⁺ is a key mediator of mitotic catastrophe induction after irradiation. These results suggest that mitochondrial fission is associated with radiation-induced mitotic catastrophe via cytosolic Ca²⁺ regulation.

Reactive Oxygen Species Drive Epigenetic Changes in Radiation-Induced Fibrosis

Radiation-induced fibrosis (RIF) develops months to years after initial radiation exposure. RIF occurs when normal fibroblasts differentiate into myofibroblasts and lay down aberrant amounts of extracellular matrix proteins. One of the main drivers for developing RIF is reactive oxygen species (ROS) generated immediately after radiation exposure. Generation of ROS is known to induce epigenetic changes and cause differentiation of fibroblasts to myofibroblasts. Several antioxidant compounds have been shown to prevent radiation-induced epigenetic changes and the development of RIF. Therefore, reviewing the ROS-linked epigenetic changes in irradiated fibroblast cells is essential to understand the development and prevention of RIF.

Evaluation of mitochondrial redox status and energy metabolism of X-irradiated HeLa cells by LC/UV, LC/MS/MS and ESR

To evaluate the metabolic responses in tumour cells exposed to ionizing radiation, oxygen consumption rate (OCR), cellular lipid peroxidation, cellular energy status (intracellular nucleotide pool and ATP production), and mitochondrial reactive oxygen species (ROS), semiquinone (SQ), and iron-sulphur (Fe-S) cluster levels were evaluated in human cervical carcinoma HeLa cells at 12 and 24 h after X-irradiation. LC/MS/MS analysis showed that levels of 8-iso PGF_2α and 5-iPF_2α-VI, lipid peroxidation products of membrane arachidonic acids, were not altered significantly in X-irradiated cells, although mitochondrial ROS levels and OCR significantly increased in the cells at 24 h after irradiation. LC/UV analysis revealed that intracellular AMP, ADP, and ATP levels increased significantly after X-irradiation, but adenylate energy charge (adenylate energy charge (AEC) = [ATP + 0.5 × ADP]/[ATP + ADP + AMP]) remained unchanged after X-irradiation. In low-temperature electron spin resonance (ESR) spectra of HeLa cells, the presence of mitochondrial SQ at g = 2.004 and Fe-S cluster at g = 1.941 was observed and X-irradiation enhanced the signal intensity of SQ but not of the Fe-S cluster. Furthermore, this radiation-induced increase in SQ signal intensity disappeared on treatment with rotenone, which inhibits electron transfer from Fe-S cluster to SQ in complex I. From these results, it was suggested that an increase in OCR and imbalance in SQ and Fe-S cluster levels, which play a critical role in the mitochondrial electron transport chain (ETC), occur after X-irradiation, resulting in an increase in ATP production and ROS leakage from the activated mitochondrial ETC.

Changes in activity and structure of lysosomes from liver of mouse irradiated in vivo

PURPOSE

Lysosomes may have an important role in response to ionizing radiation. Moreover, radiation could affect autophagy, which process involves the activity of lysosomal enzymes. In the present study, the effect of ionizing radiation on the lysosomal compartment of mouse liver was investigated after in vivo exposure.

MATERIALS AND METHODS

Morphology and ultrastructure of hepatocytes were assessed by light and electron microscopy, and activities of selected lysosomal enzymes were assessed in 12, 36 and 120 h after exposure to the mean dose of 1 Gy. The levels of autophagy-related proteins LC3-II and p62 were compared by Western blotting between untreated and irradiated animals (120 h after exposure).

RESULTS

Increased number of autophagic vacuoles in hepatocytes from exposed animals was documented in the ultrastructural study; destroyed mitochondria were the dominant component of such vacuoles. Moreover, an increased activity of lysosomal hydrolases was observed after exposure. However, levels of autophagy substrates LC3-II and p62 were barely affected in exposed animals 120 h after irradiation when the accumulation of autophagic vacuoles was observed.

CONCLUSION

Effects of irradiation included an increased number of autophagic vacuoles, especially of autophagosomes, and increased activity of lysosomal enzymes. However, putative markers of autophagic flux were not observed, which suggested suppression of the completion of the radiation-mediated autophagy pathway.

ROS-Induced DNA Damage Associates with Abundance of Mitochondrial DNA in White Blood Cells of the Untreated Schizophrenic Patients

OBJECTIVE

The aim of this study was (1) to examine the leukocyte mtDNA copy number (CN) in unmedicated (SZ (m-)) and medicated (SZ (m+)) male patients with paranoid schizophrenia (SZ) in comparison with the healthy male controls (HC) and (2) to compare the leukocyte mtDNA CN with the content of an oxidation marker 8-oxodG in lymphocytes of the SZ (m-) patients.

METHODS

We evaluated leukocyte mtDNA CN of 110 subjects with SZ in comparison with 60 male HC by the method qPCR (ratio mtDNA/nDNA (gene B2M) was detected). SZ patients were divided into two subgroups. The patients of the subgroups SZ (m+) (N = 55) were treated with standard antipsychotic medications in the hospital. The patients of the subgroup SZ (m-) (N = 55) were not treated before venous blood was sampled. To evaluate oxidative DNA damage, we quantified the levels of 8-oxodG in lymphocytes (flow cytometry) of SZ (m-) patients (N = 55) and HC (N = 30).

RESULTS

The leukocyte mtDNA CN showed no significant difference in SZ (m+) patients and HC. The mtDNA CN in the unmedicated subgroup SZ (m-) was significantly higher than that in the SZ (m+) subgroup or in HC group. The level of 8-oxodG in the subgroup SZ (m-) was significantly higher than that in HC group.

CONCLUSION

The leukocytes of the unmedicated SZ male patients with acute psychosis contain more mtDNA than the leukocytes of the male SZ patients treated with antipsychotic medications or the healthy controls. MtDNA content positively correlates with the level of 8-oxodG in the unmedicated SZ patients.

Clair DK, Kyprianou N. Profiles of Radioresistance Mechanisms in Prostate Cancer

Radiation therapy (RT) is commonly used for the treatment of localized prostate cancer (PCa). However, cancer cells often develop resistance to radiation through unknown mechanisms and pose an intractable challenge. Radiation resistance is highly unpredictable, rendering the treatment less effective in many patients and frequently causing metastasis and cancer recurrence. Understanding the molecular events that cause radioresistance in PCa will enable us to develop adjuvant treatments for enhancing the efficacy of RT. Radioresistant PCa depends on the elevated DNA repair system and the intracellular levels of reactive oxygen species (ROS) to proliferate, self-renew, and scavenge anti-cancer regimens, whereas the elevated heat shock protein 90 (HSP90) and the epithelial-mesenchymal transition (EMT) enable radioresistant PCa cells to metastasize after exposure to radiation. The up-regulation of the DNA repairing system, ROS, HSP90, and EMT effectors has been studied extensively, but not targeted by adjuvant therapy of radioresistant PCa. Here, we emphasize the effects of ionizing radiation and the mechanisms driving the emergence of radioresistant PCa. We also address the markers of radioresistance, the gene signatures for the predictive response to radiotherapy, and novel therapeutic platforms for targeting radioresistant PCa. This review provides significant insights into enhancing the current knowledge and the understanding toward optimization of these markers for the treatment of radioresistant PCa.