Differential mechanisms of x-ray-induced cell death in human endothelial progenitor cells isolated from cord blood and adults

Impacts of Radiation on Metabolism and Vascular Cell Senescence

Significance: This review investigates how radiation therapy (RT) increases the risk of delayed cardiovascular disease (CVD) in cancer survivors. Understanding the mechanisms underlying radiation-induced CVD is essential for developing targeted therapies to mitigate these effects and improve long-term outcomes for patients with cancer. Recent Advances: Recent studies have primarily focused on metabolic alterations induced by irradiation in various cancer cell types. However, there remains a significant knowledge gap regarding the role of chronic metabolic alterations in normal cells, particularly vascular cells, in the progression of CVD after RT. Critical Issues: This review centers on RT-induced metabolic alterations in vascular cells and their contribution to senescence accumulation and chronic inflammation across the vasculature post-RT. We discuss key metabolic pathways, including glycolysis, the tricarboxylic acid cycle, lipid metabolism, glutamine metabolism, and redox metabolism (nicotinamide adenine dinucleotide/Nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADP+)/NADPH). We further explore the roles of regulatory proteins such as p53, adenosine monophosphate-activated protein kinase, and mammalian target of rapamycin in driving these metabolic dysregulations. The review emphasizes the impact of immune-vascular crosstalk mediated by the senescence-associated secretory phenotype, which perpetuates metabolic dysfunction, enhances chronic inflammation, drives senescence accumulation, and causes vascular damage, ultimately contributing to cardiovascular pathogenesis. Future Directions: Future research should prioritize identifying therapeutic targets within these metabolic pathways or the immune-vascular interactions influenced by RT. Correcting metabolic dysfunction and reducing chronic inflammation through targeted therapies could significantly improve cardiovascular outcomes in cancer survivors. Antioxid. Redox Signal. 00, 000-000.

Review of Cerebral Radiotherapy-Induced Vasculopathy in Pediatric and Adult Patients

Radiation therapy (RT) causes radiation-induced vasculopathy, which requires clinicians to identify and manage this side effect in pediatric and adult patients. This article reviews previous findings about the pathophysiology of RT-induced vascular injury, including endothelial cell injury, oxidative stress, inflammatory cytokines, angiogenic pathways, and remodeling. The vasculopathy is categorized into ischemic vasculopathy, hemorrhagic vasculopathy, carotid artery injury, and other malformations (cavernous malformations and aneurysms) in populations of pediatric and adult patients separately. The prevention and management of this RT-induced side effect are also discussed. The article summarizes the distribution and risk factors of different types of RT-induced vasculopathy. This will help clinicians identify high-risk patients with corresponding vasculopathy subtypes to deduce prevention and treatment strategies accordingly.

Salvage LATTICE radiotherapy for a growing tumour despite conventional radio chemotherapy treatment of lung cancer

A 40-year-old patient with cT4cN1M0 squamous cell lung cancer of the upper right lobe received preoperative induction chemotherapy. Systemic induction treatment failed to reverse tumour growth with the addition of conventional radiotherapy (RT). A salvage lattice RT boost of 12 Gy was administered immediately to increase the dose to the tumour. Conventional RT was resumed at the planned dose of 60 Gy. The tumour shrank rapidly, and the patient was surged. The postoperative pathology remained ypT0ypN0 status.

Chest radiotherapy after left upper lobectomy may be a risk factor for thrombosis in the pulmonary vein stump

Background

Thrombosis in the pulmonary vein stump (PVS) is not a well-known complication after pulmonary lobectomy, but it has the potential to cause embolism to vital organs. The aim of this study was to evaluate the risk factors for thrombosis in the PVS after pulmonary lobectomy.

Methods

A total of 439 patients who underwent pulmonary lobectomy from 2008 to 2017 were retrospectively reviewed, and 412 patients were further analyzed. The state of the PVS was evaluated by chest contrast-enhanced computed tomography (CECT). Univariate analysis was performed to evaluate the potential risk factors for thrombosis in the PVS.

Results

Thrombosis in the PVS was detected in 6 of 412 (1.5%) patients, and 5 of them underwent left upper lobectomy (LUL) (5/100, 5.0%) (P = 0.004). In the analyses of the LUL group, postoperative chest radiotherapy was identified as a risk factor for thrombosis in the PVS (P = 0.024), and postoperative atrial fibrillation showed a tendency to be a risk factor for thrombosis (P = 0.058).

Conclusions

Chest radiotherapy after LUL is a possible risk factor for thrombosis in the PVS. Periodic chest CECT is recommended after postoperative chest radiotherapy for patients after LUL.

The Role of Oxidative Stress and Inflammation in Cardiometabolic Health of Children During Cancer Treatment and Potential Impact of Key Nutrients

Significance: The 5-year survival rate of childhood cancers is now reaching 84%. However, treatments cause numerous acute and long-term side effects. These include cardiometabolic complications, namely hypertension, dyslipidemia, hyperglycemia, insulin resistance, and increased fat mass. Recent Advances: Many antineoplastic treatments can induce oxidative stress (OxS) and trigger an inflammatory response, which may cause acute and chronic side effects. Critical Issues: Clinical studies have reported a state of heightened OxS and inflammation during cancer treatment in children as the result of treatment cytotoxic action on both cancerous and noncancerous cells. Higher levels of OxS and inflammation are associated with treatment side effects and with the development of cardiometabolic complications. Key nutrients (omega-3 polyunsaturated fatty acids, dietary antioxidants, probiotics, and prebiotics) have the potential to modulate inflammatory and oxidative responses and, therefore, could be considered in the search for adverse complication prevention means as long as antineoplastic treatment efficiency is maintained. Future Directions: There is a need to better understand the relationship between cardiometabolic complications, OxS, inflammation and diet during pediatric cancer treatment, which represents the ultimate goal of this review. Antioxid. Redox Signal. 35, 293-318.

Brain Damage and Patterns of Neurovascular Disorder after Ionizing Irradiation. Complications in Radiotherapy and Radiation Combined Injury

Exposure to ionizing radiation, mechanical trauma, toxic chemicals or infections, or combinations thereof (i.e., combined injury) can induce organic injury to brain tissues, the structural disarrangement of interactive networks of neurovascular and glial cells, as well as on arrays of the paracrine and systemic destruction. This leads to subsequent decline in cognitive capacity and decompensation of mental health. There is an ongoing need for improvement in mitigating and treating radiation- or combined injury-induced brain injury. Cranial irradiation per se can cause a multifactorial encephalopathy that occurs in a radiation dose- and time-dependent manner due to differences in radiosensitivity among the various constituents of brain parenchyma and vasculature. Of particular concern are the radiosensitivity and inflammation susceptibility of: 1. the neurogenic and oligodendrogenic niches in the subependymal and hippocampal domains; and 2. the microvascular endothelium. Thus, cranial or total-body irradiation can cause a plethora of biochemical and cellular disorders in brain tissues, including: 1. decline in neurogenesis and oligodendrogenesis; 2. impairment of the blood-brain barrier; and 3. ablation of vascular capillary. These changes, along with cerebrovascular inflammation, underlie different stages of encephalopathy, from the early protracted stage to the late delayed stage. It is evident that ionizing radiation combined with other traumatic insults such as penetrating wound, burn, blast, systemic infection and chemotherapy, among others, can exacerbate the radiation sequelae (and vice versa) with increasing severity of neurogenic and microvascular patterns of radiation brain damage.

Molecular mechanisms and cardiovascular implications of cancer therapy-induced senescence

Cancer treatment has been associated with accelerated aging that can lead to early-onset health complications typically experienced by older populations. In particular, cancer survivors have an increased risk of developing premature cardiovascular complications. In the last two decades, cellular senescence has been proposed as an important mechanism of premature cardiovascular diseases. Cancer treatments, specifically anthracyclines and radiation, have been shown to induce senescence in different types of cardiovascular cells. Additionally, clinical studies identified increased systemic markers of senescence in cancer survivors. Preclinical research has demonstrated the potential of several approaches to mitigate cancer therapy-induced senescence. However, strategies to prevent and/or treat therapy-induced cardiovascular senescence have not yet been translated to the clinic. In this review, we will discuss how therapy-induced senescence can contribute to cardiovascular complications. Thereafter, we will summarize the current in vitro, in vivo, and clinical evidence regarding cancer therapy-induced cardiovascular senescence. Then, we will discuss interventional strategies that have the potential to protect against therapy-induced cardiovascular senescence. To conclude, we will highlight challenges and future research directions to mitigate therapy-induced cardiovascular senescence in cancer survivors.

The Technical and Clinical Implementation of LATTICE Radiation Therapy (LRT)

The concept of spatially fractionated radiation therapy (SFRT) was conceived over 100 years ago, first in the form of GRID, which has been applied to clinical practice since its early inception and continued to the present even with markedly improved instrumentation in radiation therapy. LATTICE radiation therapy (LRT) was introduced in 2010 as a conceptual 3D extension of GRID therapy with several uniquely different features. Since 2014, when the first patient was treated, over 150 patients with bulky tumors worldwide have received LRT. Through a brief review of the basic principles and the analysis of the collective clinical experience, a set of technical recommendations and guidelines are proposed for the clinical implementation of LRT. It is to be recognized that the current clinical practice of SFRT (GRID or LRT) is still largely based on the heuristic principles. With advancements in basic biological research and the anticipated clinical trials to systemically assess the efficacy and risk, progressively robust optimizations of the technical parameters are essential for the broader application of SFRT in clinical practice.

Combined High-Dose LATTICE Radiation Therapy and Immune Checkpoint Blockade for Advanced Bulky Tumors: The Concept and a Case Report

Although the combination of immune checkpoint blockades with high dose of radiation has indicated the potential of co-stimulatory effects, consistent clinical outcome has been yet to be demonstrated. Bulky tumors present challenges for radiation treatment to achieve high rate of tumor control due to large tumor sizes and normal tissue toxicities. As an alternative, spatially fractionated radiotherapy (SFRT) technique has been applied, in the forms of GRID or LATTICE radiation therapy (LRT), to safely treat bulky tumors. When used alone in a single or a few fractions, GRID or LRT can be best classified as palliative or tumor de-bulking treatments. Since only a small fraction of the tumor volume receive high dose in a SFRT treatment, even with the anticipated bystander effects, total tumor eradications are rare. Backed by the evidence of immune activation of high dose radiation, it is logical to postulate that the combination of High-Dose LATTICE radiation therapy (HDLRT) with immune checkpoint blockade would be effective and could subsequently lead to improved local tumor control without added toxicities, through augmenting the effects of radiation in-situ vaccine and T-cell priming. We herein present a case of non-small cell lung cancer (NSCLC) with multiple metastases. The patient received various types of palliative radiation treatments with combined chemotherapies and immunotherapies to multiple lesions. One of the metastatic lesions measuring 63.2 cc was treated with HDLRT combined with anti-PD1 immunotherapy. The metastatic mass regressed 77.84% over one month after the treatment, and had a complete local response (CR) five months after the treatment. No treatment-related side effects were observed during the follow-up exams. None of the other lesions receiving palliative treatments achieved CR. The dramatic differential outcome of this case lends support to the aforementioned postulate and prompts for further systemic clinical studies.

Computational feasibility of simulating changes in blood flow through whole-organ vascular networks from radiation injury

Vasculature is necessary to the healthy function of most tissues. In radiation therapy, injury of the vasculature can have both beneficial and detrimental effects, such as tumor starvation, cardiac fibrosis, and white-matter necrosis. These effects are caused by changes in blood flow due to the vascular injury. Previously, research has focused on simulating the radiation injury of vasculature in small volumes of tissue, ignoring the systemic effects of local damage on blood flow. Little is known about the computational feasibility of simulating the radiation injury to whole-organ vascular networks. The goal of this study was to test the computational feasibility of simulating the dose deposition to a whole-organ vascular network and the resulting change in blood flow. To do this, we developed an amorphous track-structure model to transport radiation and combined this with existing methods to model the vasculature and blood flow rates. We assessed the algorithm's computational scalability, execution time, and memory usage. The data demonstrated it is computationally feasible to calculate the radiation dose and resulting changes in blood flow from 2 million protons to a network comprising 8.5 billion blood vessels (approximately the number in the human brain) in 87 hours using a 128-node cluster. Furthermore, the algorithm demonstrated both strong and weak scalability, meaning that additional computational resources can reduce the execution time further. These results demonstrate, for the first time, that it is computationally feasible to calculate radiation dose deposition in whole-organ vascular networks. These findings provide key insights into the computational aspects of modeling whole-organ radiation damage. Modeling the effects radiation has on vasculature could prove useful in the study of radiation effects on tissues, organs, and organisms.

Cardiovascular Damage Associated With Chest Irradiation

The improvement of anticancer-therapies results in a greater amount of long-term survivors after radiotherapy. Therefore, the understanding of cardiotoxicity after irradiation is of increasing importance. Cardiovascular adverse events after chest irradiation have been acknowledged for a long time but remain difficult to diagnose. Long-term cardiovascular adverse events may become evident years or decades after radiotherapy and the spectrum of potential cardiovascular side effects is large. Recent experimental and clinical data indicate that cardiovascular symptoms may be caused especially by heart failure with preserved ejection fraction, which remains incompletely understood in patients after radiation therapy. Heart radiation dose and co-existing cardiovascular risk factors represent some of the most important contributors for incidence and severity of radiation-induced cardiovascular side effects. In this review, we aim to elucidate the underlying patho-mechanisms and to characterize the development of radiation-induced cardiovascular damage. Additionally, approaches for clinical management and treatment options are presented.

Low dose 100 cGy irradiation as a potential therapy for pulmonary hypertension

Pulmonary hypertension (PH) is an incurable disease characterized by pulmonary vascular remodeling and ultimately death. Two rodent models of PH include treatment with monocrotaline or exposure to a vascular endothelial growth factor receptor inhibitor and hypoxia. Studies in these models indicated that damaged lung cells evolve extracellular vesicles which induce production of progenitors that travel back to the lung and induce PH. A study in patients with pulmonary myelofibrosis and PH indicated that 100 cGy lung irradiation could remit both diseases. Previous studies indicated that murine progenitors were radiosensitive at very low doses, suggesting that 100 cGy treatment of mice with induced PH might be an effective PH therapy. Our hypothesis is that the elimination of the PH‐inducing marrow cells by low dose irradiation would remove the cellular influences creating PH. Here we show that low dose whole‐body irradiation can both prevent and reverse established PH in both rodent models of PH.

Radiation-Induced Endothelial Vascular Injury: A Review of Possible Mechanisms

In radiation therapy for cancer, the therapeutic ratio represents an optimal balance between tumor control and normal tissue complications. As improvements in the therapeutic arsenal against cancer extend longevity, the importance of late effects of radiation increases, particularly those caused by vascular endothelial injury. Radiation both initiates and accelerates atherosclerosis, leading to vascular events like stroke, coronary artery disease, and peripheral artery disease. Increased levels of proinflammatory cytokines in the blood of long-term survivors of the atomic bomb suggest that radiation evokes a systemic inflammatory state responsible for chronic vascular side effects. In this review, the authors offer an overview of potential mechanisms implicated in radiation-induced vascular injury.

Cellular Senescence in the Treatment of Ovarian Cancer

OBJECTIVE

This review aimed to update the research and development of cellular senescence in the treatment of ovarian cancer. We discussed the current mechanisms of senescence and the major biomarkers of senescence, especially the methods of cellular senescence in the treatment of ovarian cancer.

MATERIALS AND METHODS

We collected all relevant studies in PubMed from 1995 to 2017. The search terms included senescence and cancer, senescence and ovarian cancer, senescence-associated secretory phenotype, ovarian cancer and chemotherapy, radiotherapy, or biotherapy. PubMed search with the key words senescence and ovarian cancer lists approximately 85 publications. After excluding the duplicated articles, we selected 68 articles most relevant to senescence and ovarian cancer in this review.

RESULTS

Cellular senescence plays a key role in various biological processes of ovarian cancer, which is closely related with the occurrence, development, and treatment of ovarian cancer. Cellular senescence on the one hand can reduce the dose of chemotherapy in ovarian cancer; on the other hand, it also can solve the problem of tumor resistance to apoptosis. Therefore, cellular senescence has been shown to be the third intracellular mechanism of ovarian cancer prevention followed by cellular DNA repair and apoptosis.

CONCLUSIONS

In the near future, cellular senescence therapy could be a powerful tool for ovarian cancer treatment.

Tumor Cell-Accelerated Senescence Is Associated With DNA-PKcs Status and Telomere Dysfunction Induced by Radiation

Whether telomere structure integrity is related to radiosensitivity is not well investigated thus far. In this study, we investigated the relation between telomere instability and radiation-induced accelerated senescence. Partial knockdown of DNA-dependent catalytic subunit of protein kinase (DNA-PKcs) in human breast cancer cell line MCF-7 was established by small interfering RNA. Radiosensitivity of control and DNA-PKcs knockdown MCF-7 cells was analyzed by clonogenetic assay. Cell growth was measured by real-time cell electronic sensing. Senescence and apoptosis were evaluated by β-galactosidase histochemical staining and fluorescence-activated cell sorting, respectively. DNA damage was determined by long polymerase chain reaction (PCR). Telomere length and integrity were analyzed by real-time PCR and cytogenetic assay, respectively. DNA-PKcs knockdown MCF-7 cells were more sensitive to X-irradiation than control cells. Further investigation revealed that accelerated senescence is more pronounced than apoptosis in cells after radiation, particularly in DNA-PKcs knockdown cells. The cytogenetic assay and kinetics of DNA damage repair revealed that the role of telomere end-capping in DNA-PKcs, rather than DNA damage repair, was more relevant to radiosensitivity. To our knowledge, this is the first study to show that DNA-PKcs plays an important role in radiation-induced accelerated senescence via maintenance of telomere integrity in MCF-7 cells. These results could be useful for future understanding of the radiation-induced genome instability and its consequences.

Common carotid artery dissection caused by radiotherapy: A case report

In the present study, a case of acute cerebral infarction with radiation-induced carotid artery dissection is reported. Carotid artery dissection is generally asymptomatic at the early stages. Due to the non-specific clinical manifestations of carotid artery dissection, a detailed inquiry of the past history of a patient has a critical role in making a diagnosis of radiation-induced common carotid artery dissection. Onset of acute ischemic stroke is the predominant manifestation, and for patients with a history of head-and-neck radiotherapy, dissection should be considered. The condition may progress rapidly, and result in a poor prognosis. Therefore, a correct early diagnosis and initiation of appropriate therapy may lead to rapid recovery, and influence the overall prognosis.

Ionizing Radiation-Induced Endothelial Cell Senescence and Cardiovascular Diseases

Exposure to ionizing radiation induces not only apoptosis but also senescence. While the role of endothelial cell apoptosis in mediating radiation-induced acute tissue injury has been extensively studied, little is known about the role of endothelial cell senescence in the pathogenesis of radiation-induced late effects. Senescent endothelial cells exhibit decreased production of nitric oxide and expression of thrombomodulin, increased expression of adhesion molecules, elevated production of reactive oxygen species and inflammatory cytokines and an inability to proliferate and form capillary-like structures in vitro. These findings suggest that endothelial cell senescence can lead to endothelial dysfunction by dysregulation of vasodilation and hemostasis, induction of oxidative stress and inflammation and inhibition of angiogenesis, which can potentially contribute to radiation-induced late effects such as cardiovascular diseases (CVDs). In this article, we discuss the mechanisms by which radiation induces endothelial cell senescence, the roles of endothelial cell senescence in radiation-induced CVDs and potential strategies to prevent, mitigate and treat radiation-induced CVDs by targeting senescent endothelial cells.

Irradiated human endothelial progenitor cells induce bystander killing in human non-small cell lung and pancreatic cancer cells

Purpose To investigate whether irradiated human endothelial progenitor cells (hEPC) could induce bystander killing in the A549 non-small cell lung cancer (NSCLC) cells and help explain the improved radiation-induced tumor cures observed in A549 tumor xenografts co-injected with hEPC. Materials and methods We investigated whether co-injection of CBM3 hEPC with A549 NSCLC cells would alter tumor xenograft growth rate or tumor cure after a single dose of 0 or 5 Gy of X-rays. We then utilized dual chamber Transwell dishes, to test whether medium from irradiated CBM3 and CBM4 hEPC would induce bystander cell killing in A549 cells, and as an additional control, in human pancreatic cancer MIA PaCa-2 cells. The CBM3 and CBM4 hEPC were plated into the upper Transwell chamber and the A549 or MIA PaCa-2 cells were plated in the lower Transwell chamber. The top inserts with the CBM3 or CBM4 hEPC cells were subsequently removed, irradiated, and then placed back into the Transwell dish for 3 h to allow for diffusion of any potential bystander factors from the irradiated hEPC in the upper chamber through the permeable membrane to the unirradiated cancer cells in the lower chamber. After the 3 h incubation, the cancer cells were re-plated for clonogenic survival. Results We found that co-injection of CBM3 hEPC with A549 NSCLC cells significantly increased the tumor growth rate compared to A549 cells alone, but paradoxically also increased A549 tumor cure after a single dose of 5 Gy of X-rays (p < 0.05). We hypothesized that irradiated hEPC may be inducing bystander killing in the A549 NSCLC cells in tumor xenografts, thus improving tumor cure. Bystander studies clearly showed that exposure to the medium from irradiated CBM3 and CBM4 hEPC induced significant bystander killing and decreased the surviving fraction of A549 and MIA PaCa-2 cells to 0.46 (46%) ± 0.22 and 0.74 ± 0.07 (74%) respectively (p < 0.005, p < 0.0001). In addition, antibody depletion studies demonstrated that the bystander killing induced in both A549 and MIA PaCa-2 cells was mediated by the cytokines TNF-α and TGF-β (p < 0.05). Conclusions These data provide evidence that irradiated hEPC can induce strong bystander killing in A549 and MIA PaCa-2 human cancer cells and that this bystander killing is mediated by the cytokines TNF-α and TGF-β.

DNA damage response (DDR) pathway engagement in cisplatin radiosensitization of non-small cell lung cancer

Non-small cell lung cancers (NSCLC) are commonly treated with a platinum-based chemotherapy such as cisplatin (CDDP) in combination with ionizing radiation (IR). Although clinical trials have demonstrated that the combination of CDDP and IR appear to be synergistic in terms of therapeutic efficacy, the mechanism of synergism remains largely uncharacterized. We investigated the role of the DNA damage response (DDR) in CDDP radiosensitization using two NSCLC cell lines. Using clonogenic survival assays, we determined that the cooperative cytotoxicity of CDDP and IR treatment is sequence dependent, requiring administration of CDDP prior to IR (CDDP-IR). We identified and interrogated the unique time and agent-dependent activation of the DDR in NSCLC cells treated with cisplatin-IR combination therapy. Compared to treatment with CDDP or IR alone, CDDP-IR combination treatment led to persistence of γH2Ax foci, a marker of DNA double-strand breaks (DSB), for up to 24h after treatment. Interestingly, pharmacologic inhibition of DDR sensor kinases revealed the persistence of γ-H2Ax foci in CDDP-IR treated cells is independent of kinase activation. Taken together, our data suggest that delayed repair of DSBs in NSCLC cells treated with CDDP-IR contributes to CDDP radiosensitization and that alterations of the DDR pathways by inhibition of specific DDR kinases can augment CDDP-IR cytotoxicity by a complementary mechanism.

Oxidative stress of brain and liver is increased by Wi-Fi (2.45GHz) exposure of rats during pregnancy and the development of newborns

An excessive production of reactive oxygen substances (ROS) and reduced antioxidant defence systems resulting from electromagnetic radiation (EMR) exposure may lead to oxidative brain and liver damage and degradation of membranes during pregnancy and development of rat pups. We aimed to investigate the effects of Wi-Fi-induced EMR on the brain and liver antioxidant redox systems in the rat during pregnancy and development. Sixteen pregnant rats and their 48 newborns were equally divided into control and EMR groups. The EMR groups were exposed to 2.45GHz EMR (1h/day for 5 days/week) from pregnancy to 3 weeks of age. Brain cortex and liver samples were taken from the newborns between the first and third weeks. In the EMR groups, lipid peroxidation levels in the brain and liver were increased following EMR exposure; however, the glutathione peroxidase (GSH-Px) activity, and vitamin A, vitamin E and β-carotene concentrations were decreased in the brain and liver. Glutathione (GSH) and vitamin C concentrations in the brain were also lower in the EMR groups than in the controls; however, their concentrations did not change in the liver. In conclusion, Wi-Fi-induced oxidative stress in the brain and liver of developing rats was the result of reduced GSH-Px, GSH and antioxidant vitamin concentrations. Moreover, the brain seemed to be more sensitive to oxidative injury compared to the liver in the development of newborns.

Differences in Circulating Endothelial Progenitor Cells among Childhood Cancer Survivors Treated with and without Radiation

Radiation during childhood cancer treatment increases the propensity to atherosclerotic cardiovascular disease among adult survivors of childhood cancer. This is thought to be mediated through the damage to the underlying vascular endothelium. Endothelial progenitor cells (EPCs) involved in vascular endothelial repair after its damage may be affected by radiation therapy but have never been investigated in adult survivors of childhood cancer. In this pilot study, utilizing multi-parametric flowcytometry, endothelial colony forming cells (ECFCs), which are the bonafide EPCs, and circulating endothelial cells (CECs), which are not EPCs, were compared between adult survivors of childhood cancer with or without radiation exposure. In addition, their associations with blood-pressure, physical activity and diet were examined. Survivors who received radiotherapy had lower ECFCs and CECs (p<0.05) compared to those without it. Significant positive correlations included physical activity with ECFCs and diet with CECs, while blood-pressure negatively correlated with ECFCs. Further evaluation is needed to examine the effect of radiation and modifiable risk factors on ECFCs and CECs. The preliminary findings from this study suggest evidence of the role of ECFCs as biomarkers of vascular injury following treatment for childhood cancer that may help in early identification of survivors at risk for cardiovascular disease.

Comparison of Fibronectin and Collagen in Supporting the Isolation and Expansion of Endothelial Progenitor Cells from Human Adult Peripheral Blood

Background

Endothelial colony-forming cells (ECFCs), are circulating endothelial progenitor cells increasingly studied in various diseases because of their potential for clinical translation. Experimental procedures for their ex vivo culture still lack standardization. In particular two different extracellular matrix proteins, either fibronectin or collagen, are commonly used by different Authors for coating plastic plates, both allowing to obtain cells that have all the features of ECFCs. However, possible differences in the impact of each substrate on ECFCs have not been analysed, so far. Therefore, in this study we investigated whether fibronectin and collagen may differentially affect ECFC cultures.

Methodology/Principal Findings

ECFCs were isolated and cultured from peripheral blood mononuclear cells of healthy donors. The impact of fibronectin compared with collagen as the only variable of the experimental procedure was analysed separately in the phase of isolation of ECFC colonies and in the following phase of cell expansion. In the isolation phase, although similar frequencies of colonies were obtained on the two substrates, ECFC colonies appeared some days earlier when mononuclear cells were seeded on fibronectin rather than collagen. In the expansion phase, ECFCs cultured on collagen showed a longer lifespan and higher cell yields compared with ECFCs cultured on fibronectin, possibly related to the higher levels of IL-6 and IL-8 measured in their supernatants. ECFCs cultured on both substrates showed similar immunophenotype and ability for in vitro tube formation.

Conclusions/Significance

Overall, the results of this study indicate that, although both fibronectin and collagen efficiently sustain ECFC cultures, each of them brings some advantages within individual steps of the entire process. We suggest that colony isolation performed on fibronectin followed by cell expansion performed on collagen may represent a novel and the most efficient strategy to obtain ECFCs from adult peripheral blood samples.

Radiation-induced loss of cell surface CD47 enhances immune-mediated clearance of human papillomavirus-positive cancer

The increasing incidence of human papillomavirus (HPV) related oropharyngeal squamous cell carcinoma (OSSC) demands development of novel therapies. Despite presenting at a more advanced stage, HPV(+) oropharyngeal squamous cell carcinoma (OSCC) have a better prognosis than their HPV(-) counterparts. We have previously demonstrated that clearance of HPV(+) OSCC during treatment with radiation and chemotherapy requires an immune response which is likely responsible for the improved clinical outcomes. To further elucidate the mechanism of immune-mediated clearance, we asked whether radiation therapy induces tumor cell changes that allow the body to recognize and aid in tumor clearance. Here, we describe a radiation-induced change in tumor surface protein expression that is critical for immune-mediated clearance. Radiation therapy decreases surface expression of CD47, a self-marker. CD47 is frequently overexpressed in head and neck squamous cell carcinoma and radiation induces a decrease of CD47 in a dose-dependent manner. We show that both in vitro and in vivo tumor cell CD47 protein levels are restored over time after sublethal radiation exposure and that protein levels on adjacent, normal tissues remain unaffected. Furthermore, reduction of tumor cell CD47 increases phagocytosis of these cells by dendritic cells and leads to increased interferon gamma and granzyme production from mixed lymphocytes. Finally, decreasing tumor cell CD47 in combination with standard radiation and chemotherapy results in improved immune-mediated tumor clearance in vivo. These findings help define an important mechanism of radiation-related immune clearance and suggest that decreasing CD47 specifically on tumor cells may be a good therapeutic target for HPV related disease.

Genetic module and miRNome trait analyses reflect the distinct biological features of endothelial progenitor cells from different anatomic locations

Background

Endothelial progenitor cells (EPCs) play a fundamental role in post-natal vascular repair, yet EPCs from different anatomic locations possess unique biological properties. The underlying mechanisms are unclear.

Results

EPCs from CB expressed abundant genes involved in cell cycle, hypoxia signalling and blood vessel development, correlating with the phenotypes that CB-EPCs proliferated more rapidly, migrated faster, and formed tubule structure more efficiently. smRNA-seq further deciphered miRNome patterns in EPCs isolated from CB or PB: 54 miRNAs were enriched in CB-EPCs, while another 50 in PB-EPCs. Specifically, CB-EPCs expressed more angiogenic miRNAs such as miR-31, while PB-EPCs possessed more tumor suppressive miRNAs including miR-10a. Knocking down miR-31 levels in CB-EPCs suppressed cell migration and microtubule formation, while overexpressing miR-31 in PB-EPCs helped to recapitulate some of CB-EPC functions.

Conclusions

Our results show the foundation for a more detailed understanding of EPCs from different anatomic sources. Stimulating the expression of angiogenic microRNAs or genes in EPCs of low activity (such as those from patients with cardiovascular diseases) might allow the development of novel therapeutic strategies.

The convergence of radiation and immunogenic cell death signaling pathways

Ionizing radiation (IR) triggers programmed cell death in tumor cells through a variety of highly regulated processes. Radiation-induced tumor cell death has been studied extensively in vitro and is widely attributed to multiple distinct mechanisms, including apoptosis, necrosis, mitotic catastrophe (MC), autophagy, and senescence, which may occur concurrently. When considering tumor cell death in the context of an organism, an emerging body of evidence suggests there is a reciprocal relationship in which radiation stimulates the immune system, which in turn contributes to tumor cell kill. As a result, traditional measurements of radiation-induced tumor cell death, in vitro, fail to represent the extent of clinically observed responses, including reductions in loco-regional failure rates and improvements in metastases free and overall survival. Hence, understanding the immunological responses to the type of radiation-induced cell death is critical. In this review, the mechanisms of radiation-induced tumor cell death are described, with particular focus on immunogenic cell death (ICD). Strategies combining radiotherapy with specific chemotherapies or immunotherapies capable of inducing a repertoire of cancer specific immunogens might potentiate tumor control not only by enhancing cell kill but also through the induction of a successful anti-tumor vaccination that improves patient survival.