Elevated Radiosensitivity Research Articles

Targeting miR-31 represses tumourigenesis and dedifferentiation of BRAFV600E-associated thyroid carcinoma.

BRAFV600E is the most common genetic mutation in differentiated thyroid cancer (DTC) occurring in 60% of patients and drives malignant tumour cell phenotypes including proliferation, metastasis and immune-escape. BRAFV600E-mutated papillary thyroid cancer (PTC) also displays greatly reduced expression of thyroid differentiation markers, thus tendency to radioactive iodine (RAI) refractory and poor prognosis. Therefore, understanding the molecular mechanisms and main oncogenic events underlying BRAFV600E will guide future therapy development. Bioinformatics and clinical specimen analyses, genetic manipulation of BRAFV600E-induced PTC model, functional and mechanism exploration guided with transcriptomic screening, as well as systematic rescue experiments were applied to investigate miR-31 function within BRAFV600E-induced thyroid cancer development. Besides, nanoparticles carrying miR-31 antagomirs were testified to alleviate 131I iodide therapy on PTC models. We identify miR-31 as a significantly increased onco-miR in BRAFV600E-associated PTC that promotes tumour progression, metastasis and RAI refractoriness via sustained Wnt/β-catenin signalling. Mechanistically, highly activated BRAF/MAPK pathway induces miR-31 expression via c-Jun-mediated transcriptional regulation across in vitro and transgenic mouse models. MiR-31 in turn facilitates β-catenin stabilisation via directly repressing tumour suppressors CEBPA and DACH1, which direct the expression of multiple essential Wnt/β-catenin pathway inhibitors. Genetic functional assays showed that thyroid-specific knockout of miR-31 inhibited BRAFV600E-induced PTC progression, and strikingly, enhanced expression of sodium-iodide symporter and other thyroid differentiation markers, thus promoted 131I uptake. Nanoparticle-mediated application of anti-miR-31 antagomirs markedly elevated radio-sensitivity of BRAFV600E-induced PTC tumours to 131I therapy, and efficiently suppressed tumour progression in the pre-clinical mouse model. Our findings elucidate a novel BRAF/MAPK-miR-31-Wnt/β-catenin regulatory mechanism underlying clinically BRAFV600E-associated DTC tumourigenesis and dedifferentiation, also highlight a potential adjuvant therapeutic strategy for advanced DTC.

Knockdown of circ_0005615 enhances the radiosensitivity of colorectal cancer by regulating the miR-665/NOTCH1 axis.

Radiotherapy resistance is a challenge for colorectal cancer (CRC) treatment. Circular RNAs (circRNAs) play vital roles in the occurrence and development of CRC. This study aimed to investigate the role of circ_0005615 in regulating the radiosensitivity of CRC. The levels of circ_0005615, microRNA-665 (miR-665), and notch receptor 1 (NOTCH1) were detected by quantitative real-time PCR or western blot. The radiosensitivity of CRC cells was assessed by colony formation assay. Cell viability, apoptosis, and colony formation were assessed by Cell Counting Kit-8 assay, flow cytometry, and colony formation assay. Cell migration and invasion were confirmed by transwell assay and scratch assay. The binding relationship between miR-665 and circ_0005615 or NOTCH1 was verified by dual-luciferase reporter assay. Xenograft assay was used to test the effect of circ_0005615 on radiosensitivity in vivo. circ_0005615 and NOTCH1 were up-regulated, and miR-665 was down-regulated in CRC tissues and cells. Radiation decreased circ_0005615 and NOTCH1 levels and increased miR-665 level. Knockdown of circ_0005615 enhanced radiosensitivity of CRC cells. Moreover, circ_0005615 sponged miR-665 to regulate the radioresistance of CRC cells. Besides, miR-665 targeted NOTCH1 to mediate the radiosensitivity of CRC cells. Furthermore, circ_0005615 depletion increased CRC radiosensitivity in vivo. circ_0005615 silencing elevated radiosensitivity of CRC by regulating miR-665/NOTCH1 axis.

The Correlation Between CD44 and Angiogenesis in Oral Squamous Cell Carcinoma Induced in Buccal Pouch in Syrian Hamster that Underwent Radiotherapy.

Angiogenesis with radiotherapy is a significant focus of recent studies to confirm the importance of combined treatments, as vascular control can have a great therapeutic target. Vascular endothelial growth factor is the key mediator of angiogenesis in cancer. In addition, some studies suggest the value of CD44 as a potential early marker of angiogenesis. Investigating the expression of vascular endothelial growth factor (VEGF) and CD44 in oral squamous cell carcinoma (OSCC) after inducing it in hamsters then undergoing radiotherapy and comparing outcomes before and after therapy to verify changes of these markers. an experimental study consisted of 18 samples of OSCC which induced in right buccal pouch of hamsters (group1) and 18 samples of OSCC which induced in the same way and were exposed to radiation therapy (group2), Biopsies were taken and fixed with formalin, paraffin waxed in conventional H&E and immunostained with monoclonal anti-VEGF and anti-CD44. our findings didn't reveal a statistically significant difference in the expression of VEGF(p =0.342) and CD44 (p=0.187) between group1 & group 2. moreover, we found tumor cells which weren't affected and resistant to radiotherapy, also revealed positive expression of VEGF & CD44, otherwise, we noticed Pearson coefficient was a significant correlation that indicated to a moderate relation. cancerous cells that showed a high expression of these markers, give elevated radiosensitivity and resist the treatment. Subsequently, we assure the importance of applying anti-VEGF and/or anti-CD44 as a supportive therapy with radiation therapy.

Circ_0010235 Regulates HOXA10 Expression to Promote Malignant Phenotypes and Radioresistance in Non-small Cell Lung Cancer Cells Via Decoying miR-588.

Background:Circular RNAs (circRNAs) are key modulators in carcinogenesis and radioresistance in multiple kinds of human cancers.Aims:To explore the role of circ_0010235 in non-small cell lung cancer (NSCLC).Study Design:Cell culture study and animal study.Methods:The detection of circ_0010235, microRNA-588 (miR-588), and homeobox protein A10 (HOXA10) was implemented via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). CCK-8, EdU, flow cytometry, transwell, and wound healing assays. These strategies were applied to evaluate cell functions. The western blot technique was employed for protein examination. The colony formation assay was used to determine cell survival after radiation treatment. In vivo research was performed by tumor xenograft assay. The binding analysis was also carried out through dual-luciferase reporter and RNA immunoprecipitation studies.Results:Circ_0010235 had an enhanced expression in NSCLC. Circ_0010235 deficiency inhibited cell proliferation, invasiveness, and migratory ability but promoted apoptosis and radiosensitivity. Downregulation of circ_0010235 decelerated tumor growth and promoted radiation sensitivity in vivo. Circ_0010235 was controlled biologically in NSCLC cells by combining with miR-588 and targeting miR-588. HOXA10 acted as a target of miR-588. MiR-588 upregulation inhibited NSCLC cell malignant phenotypes and elevated radiosensitivity via downregulating HOXA10. Circ_0010235 could regulate the level of HOXA10 by sponging miR-588.Conclusion:Circ_0010235 contributed to the malignant progression of NSCLC, but suppressed the radiation sensitivity via targeting miR-588 to induce HOXA10 upregulation.

Hsa_circ_0014879 regulates the radiosensitivity of esophageal squamous cell carcinoma through miR-519-3p/CDC25A axis.

Circular RNAs (circRNAs) play critical roles in regulating the radiosensitivity of various cancers, including esophageal squamous cell carcinoma (ESCC). This research aimed to explore the role and potential mechanism of hsa_circ_0014879 in regulating ESCC radioresistance. The levels of hsa_circ_0014879, microRNA-519-3p (miR-519-3p) and cell division cycle 25A (CDC25A) were measured using quantitative real-time PCR or western blot. Cell proliferation was evaluated by colony formation assay. Cell migration and invasion were assessed by transwell and scratch assays. The levels of epithelial-mesenchymal transition (EMT)-related proteins were detected by western blot. Xenograft assay was used to analyze the effect of hsa_circ_0014879 on radiosensitivity in vivo. The binding relationship among hsa_circ_0014879, miR-519-3p and CDC25A was confirmed by dual-luciferase reporter assay. Hsa_circ_0014879 and CDC25A were upregulated, whereas miR-519-3p was downregulated in radio-resistant ESCC tissues and cells. Depletion of hsa_circ_0014879 suppressed the proliferation, migration and invasion of radio-resistant ESCC cells. Hsa_circ_0014879 knockdown elevated radiosensitivity of radio-resistant cells by modulating miR-519-3p. Moreover, miR-519-3p enhanced the radiosensitivity of radio-resistant cells by targeting CDC25A. Also, hsa_circ_0014879 upregulated CDC25A via sponging miR-519-3p. Hsa_circ_0014879 silencing enhanced the radiosensitivity of ESCC via regulating the miR-519-3p/CDC25A pathway.

Downregulation of lncRNA XIST Represses Tumor Growth and Boosts Radiosensitivity of Neuroblastoma via Modulation of the miR-375/L1CAM Axis

Neuroblastoma (NB) is a heterogeneous tumor that is common in infants and young children. Long non-coding RNA X-inactive specific transcript (XIST) is implicated in NB advancement. Nevertheless, the role and regulatory mechanism by which XIST in NB are not fully elucidated. Expression levels of XIST, microRNA-375-5p (miR-375), and L1 cell adhesion molecular (L1CAM) were examined through quantitative real-time polymerase chain reaction (qRT-PCR). The cell cycle progression, proliferation, and colony formation of NB cells were determined with flow cytometry, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), or cell colony formation assays. Cell apoptotic rate was detected with flow cytometry assay. The relationship between XIST or L1CAM and miR-375 was verified via dual-luciferase reporter assay. The level of L1CAM protein was examined through western blotting. The role of XIST in vivo was confirmed through xenograft assay. XIST and L1CAM were upregulated while miR-375 was downregulated in NB tissues and cells. XIST depletion repressed tumor growth in vivo and elevated radiosensitivity, arrested cell cycle progression, and impeded proliferation of NB cells in vitro. Mechanistically, XIST modulated L1CAM expression through competitively binding to miR-375. Furthermore, miR-375 inhibitor recovered XIST inhibition-mediated effects on the radiosensitivity and malignant behaviors of NB cells. Also, L1CAM overexpression reversed the effects of miR-375 enhancement on the cell cycle progression, proliferation, and radiosensitivity of NB cells. XIST downregulation repressed tumor growth and boosted radiosensitivity of NB via modulating the miR-375/L1CAM axis, indicating that XIST was a promising target for NB treatment.

Epidermal growth factor receptor mutations: association with favorable local tumor control following Gamma Knife radiosurgery in patients with non-small cell lung cancer and brain metastases.

The presence of epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) has been associated with elevated radiosensitivity in vitro. However, results from clinical studies on radiosensitivity in cases of NSCLC with EGFR mutations are inconclusive. This paper presents a retrospective analysis of patients with NSCLC who underwent regular follow-up imaging after radiotherapy for brain metastases (BMs). The authors also investigated the influence of EGFR mutations on the efficacy of Gamma Knife radiosurgery (GKRS). This study included 264 patients (1069 BMs) who underwent GKRS treatment and for whom EGFR mutation status, demographics, performance status, and tumor characteristics were available. Radiological images were obtained at 3 months after GKRS and at 3-month intervals thereafter. Kaplan-Meier plots and Cox regression analysis were used to correlate EGFR mutation status and other clinical features with tumor control and overall survival. The tumor control rates and overall 12-month survival rates were 87.8% and 65.5%, respectively. Tumor control rates in the EGFR mutant group versus the EGFR wild-type group were 90.5% versus 79.4% at 12 months and 75.0% versus 24.5% at 24 months. During the 2-year follow-up period after SRS, the intracranial response rate in the EGFR mutant group was approximately 3-fold higher than that in the wild-type group (p < 0.001). Cox regression multivariate analysis identified EGFR mutation status, extracranial metastasis, primary tumor control, and prescribed margin dose as predictors of tumor control (p = 0.004, p < 0.001, p = 0.004, and p = 0.026, respectively). Treatment with a combination of GKRS and tyrosine kinase inhibitors (TKIs) was the most important predictor of overall survival (p < 0.001). The current study demonstrated that, among patients with NSCLC-BMs, EGFR mutations were independent prognostic factors of tumor control. It was also determined that a combination of GKRS and TKI had the most pronounced effect on prolonging survival after SRS. In select patient groups, treatment with SRS in conjunction with EGFR-TKIs provided effective tumor control for NSCLC-BMs.

Hypoxia inducible factor-1α/B-cell lymphoma 2 signaling impacts radiosensitivity of H1299 non-small cell lung cancer cells in a normoxic environment.

Hypoxia inducible factor-1α (HIF-1α) is a critical transcriptional factor for the response of cells to hypoxic microenvironment and its expression induces resistance of hypoxic non-small-cell lung cancer (NSCLC) cells to radiotherapy. This study investigated how the activation of HIF-1α/B-cell lymphoma 2 (BCL-2) signaling under normoxic conditions impacted radiosensitivity of NSCLC cells. The recombinant pcDNA3.0-EGFP plasmids with wild-type or mutant HIF-1α complementary DNA (cDNA) were transfected into H1299 cells, an NSCLC cell line, establishing two H1299 sublines with high expression of HIF-1α. Compared with the levels of HIF-1α and BCL-2 proteins in non-transfected cells, increased levels of both proteins were found in transfected cells. Moreover, the expression of HIF-1α in non-transfected cells induced by chloride cobalt (CoCl2), a commonly used mimetic hypoxia reagent, was concomitant with the enhancement of BCL-2 expression. Conversely, reduction of HIF-1α expression by an inhibitor decreased the levels of BCL-2 proteins. The results revealed that the stabilization and expression of HIF-1α promoted the accumulation of BCL-2 proteins in H1299 cells. Subsequent experiments showed that intracellular HIF-1α/BCL-2 signaling was triggered in a normoxic environment after H1299 cells were exposed to irradiation, causing an elevated radioresistance. In contrast, blockage of HIF-1α/BCL-2 signaling leads to an elevated radiosensitivity. Proliferation of cells assay showed that, under normoxic conditions, population doubling times (PDTs) of irradiated cells were prolonged by suppression of HIF-1α/BCL-2 signaling. It is, therefore, indicated that HIF-1α/BCL-2 signaling activated by ionizing radiation reduces the radiosensitivity of H1299 cells independent of the hypoxic environment.

Human factor in exposure from conventional radiographic examinations in very and extremely low birth weight patients

Very premature neonates’ survival involves the application of modern intensive care interventions which currently are accompanied by frequent radiographic examinations. Elevated radiosensitivity of neonates and a large number of examinations performed during their prolonged hospitalisation raise the question of the risks of cancer from exposure to ionising radiation considering their greater remaining lifetime. Impossibility to substitute conventional radiography with another type of examination not involving radiation exposure stimulates the analysis of hospital's routine practices aimed to minimise the dose received by neonates. In the present work we compare the radiographic techniques applied by 17 radiographers at examination of patients with birth weight lower than 1500 g in one paediatric hospital in Brazil. Their impact on patient dose is analysed considering patient weight and examination type. On the whole, the radiographers do not take into account examination type and patient weight. The mean kVp values differ up to 20%, which could lead to doubling of the dose and the difference in mAs values may cause tripling of the dose. The mean dose values differed by a factor of 3–4. The dose may be decreased to 50–60 μGy per examination.

Simvastatin Sensitizes Radioresistant Prostate Cancer Cells by Compromising DNA Double-Strand Break Repair.

Prostate cancer (PCa) is one of the most prevalent male cancers in western world. Radiation therapy (RT) is commonly used to treat PCa patients. However, a certain proportion of patients develop radioresistant PCa cells, which results in metastatic disease. Statins, which inhibit 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase, are commonly used to treat hypercholesterolemia, exhibiting beneficial effects on cardiovascular diseases and on several types of cancers, including PCa. However, the mechanistic details and crosstalk between statins and RT in PCa cells remain unknown. In this study, radioresistant DOC-2/DAB2 interactive protein (DAB2IP)-deficient PCa cells were used to evaluate whether simvastatin could enhance the effect of ionizing radiation (IR). The crucial molecules that associated with simvastatin elevated radiosensitivity in PCa cells were explored. Our results demonstrated that a combination treatment with simvastatin and IR synergistically induced apoptosis of radioresistant PCa cells. In addition, simvastatin appeared to compromise DNA double-strand breaks repair by activating the expressions of histone 2A family member X (γ-H2AX) and phospho-checkpoint kinase 1 (p-CHK1), suggesting an underlying mechanism for this radiosensitization of PCa cells. These findings reveal that simvastatin may be a potent therapeutic agent for co-treatment with radiation to overcome radioresistance in PCa cells.

HDAC6 inhibition induces glioma stem cells differentiation and enhances cellular radiation sensitivity through the SHH/Gli1 signaling pathway

The existence of small numbers of stem-like cells, called glioma stem cells (GSCs), in human glioblastoma multiforme (GBM) is responsible for recurrence due to resistance to radiotherapy and chemotherapy. Inhibition of histone deacetylase 6 (HDAC6) enhanced radiosensitivity of cancer cells. However, the effect of inhibiting HDAC6 on stemness and radioresistance of GSCs and its molecular mechanism are largely unknown. In the present study, we found that HDAC6 was upregulated in GSCs comparing to non-stem tumor cells. Inhibiting HDAC6 downregulated glioma-associated oncogene homolog 1 (Gli1), Patched (Ptch1 and Ptch2) receptors, components of SHH signal, expression and activity in GSCs. Restraining HDAC6 decreased cell proliferation, induces differentiation and increased apoptosis of GSCs via inactivation of SHH/Gli1 signaling pathway. Moreover, HDAC6 inhibition decreased DNA damage repair capacity of GSCs through degradation of checkpoint kinase (CHK) 1 caused by X-linked inhibitor of apoptosis (XIAP) downregulation, leading to elevated radiosensitivity. Taken together, these findings indicate that HDAC6 inhibition decreased stemness of GSCs and enhanced GSCs radiosensitivity through inactivating SHH/Gli1 pathway. This provides a promising novel drug target to overcome GSCs stemness and radioresistance.

Radiation exposure from conventional radiographic examinations in very and extremely low birth weight patients

The survival of very premature neonates has improved significantly at the last decades owing to the utilization of modern intensive care interventions that usually requires prolonged hospitalisation and are accompanied by frequent radiographic examinations. Their elevated radiosensitivity and numerous examinations combined with their greater remaining lifetime raise the issue of high risk for radiation-induced malignancies. Because it is presently impossible to substitute this type of examinations with others that do not involve radiation exposure, investigations on a hospital's routine practices becomes relevant. In this work, we present the results of an investigation on the radiation exposure of patients with birth weight lower than 1500g in one paediatric hospital in Brazil. We analyse some important patient characteristics, like weight, gestational age, length of stay, and number of radiographs performed in the neonatal intensive care unit, in connection with the patient dose. The obtained results are compared with the existing information from other studies.

Asparagine 326 in the extremely C-terminal region of XRCC4 is essential for the cell survival after irradiation

XRCC4 is one of the crucial proteins in the repair of DNA double-strand break (DSB) through non-homologous end-joining (NHEJ). As XRCC4 consists of 336 amino acids, N-terminal 200 amino acids include domains for dimerization and for association with DNA ligase IV and XLF and shown to be essential for XRCC4 function in DSB repair and V(D)J recombination. On the other hand, the role of the remaining C-terminal region of XRCC4 is not well understood. In the present study, we noticed that a stretch of ∼20 amino acids located at the extreme C-terminus of XRCC4 is highly conserved among vertebrate species. To explore its possible importance, series of mutants in this region were constructed and assessed for the functionality in terms of ability to rescue radiosensitivity of M10 cells lacking XRCC4. Among 13 mutants, M10 transfectant with N326L mutant (M10-XRCC4N326L) showed elevated radiosensitivity. N326L protein showed defective nuclear localization. N326L sequence matched the consensus sequence of nuclear export signal. Leptomycin B treatment accumulated XRCC4N326L in the nucleus but only partially rescued radiosensitivity of M10-XRCC4N326L. These results collectively indicated that the functional defects of XRCC4N326L might be partially, but not solely, due to its exclusion from nucleus by synthetic nuclear export signal. Further mutation of XRCC4 Asn326 to other amino acids, i.e., alanine, aspartic acid or glutamine did not affect the nuclear localization but still exhibited radiosensitivity. The present results indicated the importance of the extremely C-terminal region of XRCC4 and, especially, Asn326 therein.

Radiation protection in paediatrics age

Radiological protection in paediatric population from medical imaging is a subject promoted by various international associations and it is becoming a main field of interest. Paediatric patients have a significant risk from ionizing radiation (IR) following X-ray examination (chest, abdomen and skeletal segments), multidetector CT (MDCT) and PET imaging [1]. Their greater damage’s risk is due to: growing tissues with elevated turnover and high radio sensitivity cellular, the high water content which amplifies the damage, the small body size that involves the exposure of large areas associated with the expectation of long- life makes possible the development of diseases resulting from genetic damage [1]. Also there is a huge increase of exposure due to imaging is recorded in many country also in Italy, in emergency and is mainly performed in “non paediatric hospitals” often with adult setting of the machine [2]. The first type of radioprotection is the use of alternatives imaging techniques; ETG and MR offer, in expert hands, a vital potential diagnostic in complete safety radio protectionist [3]. The radiologist who elects to perform the X-ray examination must be certain that this is justified and run with minimal doses for the same diagnostic benefit (As Low As Reasonably Achievable: ALARA). In these patients the X-ray studies is characterized by repeated examinations and this results in high doses even if only one exam does not deliver high levels of IR. MDCT examinations when strictly necessary, should be optimized “patient fit” in terms of scanning parameters mAs and Kw (according to age and weight of the patient the paediatric patient range from 700gr to 90 kgs), well collimation and only the region of interest should be examined and multiple sequence should be avoided [4]. Is a common idea that using paediatric protocols and alternative imaging techniques are important for reduce dose [4] and many authors suggested that the Size-Specific Dose Estimates (SSDE) received by the patients should be included in the patient electronic medical record; paediatric radiologist and clinicians can use the SSDE when assessing risk versus benefit for the child prior to performance of a scan MDTC. The extensive use of ionizing radiation in paediatric age needs a profound balance between possible risks and clinical advantage by referring clinicians and a patient fit protocols adjusted to age and BMI of the patient by the radiologist.

Estimated risk of radiation-induced cancer following paediatric cranio-spinal irradiation with electron, photon and proton therapy

Background. Improvement in radiotherapy during the past decades has made the risk of developing a radiation-induced secondary cancer as a result of dose to normal tissue a highly relevant survivorship issue. Important factors expected to influence secondary cancer risk include dose level and dose heterogeneity, as well as gender and type of tissue irradiated. The elevated radio-sensitivity in children calls for models particularly tailored to paediatric cancer patients.Material and methods. Treatment plans of six paediatric medulloblastoma patients were analysed with respect to secondary cancer risk following cranio-spinal irradiation (CSI), using either: 1) electrons and photons combined; 2) conformal photons; 3) double-scattering (DS) protons; or 4) intensity-modulated proton therapy (IMPT). The relative organ equivalent dose (OED) concept was applied in three dose-risk scenarios: a linear response model, a plateau response and an organ specific linear-exponential response. Life attributable risk (LAR) was calculated based on the BEIR VII committee's preferred models for estimating age- and site-specific solid cancer incidence. Uncertainties in the model input parameters were evaluated by error propagation using a Monte Carlo sampling procedure.Results. Both DS protons and IMPT achieved a significantly better dose conformity compared to the photon and electron irradiation techniques resulting in a six times lower overall risk of radiation-induced cancer. Secondary cancer risk in the thyroid and lungs contributed most to the overall risk in all compared modalities, while no significant difference was observed for the bones. Variations between DS protons and IMPT were small, as were differences between electrons and photons.Conclusion. Regardless of technique, using protons decreases the estimated risk of secondary cancer following paediatric CSI compared to conventional photon and electron techniques. Substantial uncertainties in the LAR estimates support relative risk comparisons by OED.

Increased skin and mucosal toxicity in the combination of vemurafenib with radiation therapy

Palliative radiotherapy is often required for patients with metastatic malignant melanoma in the case of bone or brain metastases. Since BRAF inhibitor therapy is highly efficient in V600-mutated melanomas, there is hesitation to stop it during radiotherapy. Consequently, radiotherapy under simultaneous vemurafenib treatment is frequently needed. We report the case of a patient receiving palliative radiotherapy of spinal bone metastases before and during vemurafenib therapy. The skin reactions were quantitatively scored using computer-assisted digital image evaluation. Radiotherapy without vemurafenib was tolerated very well, whereas radiotherapy under simultaneous vemurafenib treatment resulted in accentuated skin reactions. Furthermore, the patient developed dysphagia and had to be hospitalized for parenteral nutrition. In the quantitative analysis, there was a twofold increase in pigmentation and erythema of the irradiated skin area of the thoracic spine when vemurafenib was combined with radiotherapy compared with radiotherapy treatment alone. This is the first reported case of a patient showing no complications during radiotherapy without vemurafenib but remarkable skin and mucosal toxicity under concurrent vemurafenib therapy. Thus, a genetically conditioned individually elevated radiosensitivity can definitely be excluded. Compared with other reported cases, radiosensitization was not limited to the skin, but also affected the esophageal mucosa. Vemurafenib is a strong radiosensitizer. Patients receiving radiotherapy under simultaneous vemurafenib treatment should be monitored very closely.

Cell Survival Following Radiation Exposure Requires miR-525-3p Mediated Suppression of ARRB1 and TXN1

BackgroundmicroRNAs (miRNAs) are non-coding RNAs that alter the stability and translation efficiency of messenger RNAs. Ionizing radiation (IR) induces rapid and selective changes in miRNA expression. Depletion of the miRNA processing enzymes Dicer or Ago2 reduces the capacity of cells to survive radiation exposure. Elucidation of critical radiation-regulated miRNAs and their target proteins offers a promising approach to identify new targets to increase the therapeutic effectiveness of the radiation treatment of cancer.Principal FindingsExpression of miR-525-3p is rapidly up-regulated in response to radiation. Manipulation of miR-525-3p expression in irradiated cells confirmed that this miRNA mediates the radiosensitivity of a variety of non-transformed (RPE, HUVEC) and tumor-derived cell lines (HeLa, U2-Os, EA.hy926) cell lines. Thus, anti-miR-525-3p mediated inhibition of the increase in miR-525-3p elevated radiosensitivity, while overexpression of precursor miR-525-3p conferred radioresistance. Using a proteomic approach we identified 21 radiation-regulated proteins, of which 14 were found to be candidate targets for miR-525-3p-mediated repression. Luciferase reporter assays confirmed that nine of these were indeed direct targets of miR-525-3p repression. Individual analysis of these direct targets by RNAi-mediated knockdown established that ARRB1, TXN1 and HSPA9 are essential miR-525-3p-dependent regulators of radiation sensitivity.ConclusionThe transient up-regulation of miR-525-3p, and the resultant repression of its direct targets ARRB1, TXN1 and HSPA9, is required for cell survival following irradiation. The conserved function of miR-525-3p across several cell types makes this microRNA pathway a promising target for modifying the efficacy of radiotherapy.

Topoisomerase II levels and G2 radiosensitivity in T-lymphocytes of women presenting with breast cancer

Previous studies from our laboratory have identified a link between intracellular topoisomerase IIα (topo IIα) levels and chromosomal radiosensitivity, as measured by the frequencies of chromatid breaks in the so-called G2-assay. Lower topo IIα levels were associated with reduced chromosomal radiosensitivity in cultured human cells. These findings supported a model, in which it is proposed that such chromatid breaks are the result of radiation-induced errors made by topoisomerase IIα during decatenation of chromatids. Studies from our and other laboratories, using the G2-assay, have shown that phytohaemagglutinin (PHA)-stimulated peripheral blood T-lymphocytes from 40% of female breast cancer cases show elevated chromatid break frequencies when exposed to a small standard dose of ionizing radiation, i.e. elevated above the 90th percentile of a group of female control samples. In the present study we have used a modified G2-assay to test whether elevated frequency of chromatid breaks in breast cancer cases is linked with elevated intracellular topo IIα level in PHA-stimulated T-lymphocytes, and also whether there is a general correlation between chromosomal radiosensitivity and topo IIα level. Our results confirm previous studies that 40% of breast cancer cases show elevated radiosensitivity as compared with controls. Also, the mean chromatid break frequency in breast cancer cases was significantly higher than in controls (P = 0.0001). We found that the mean topo IIα level in the cohort of breast cancer cases studied was significantly raised, as compared with controls (P = 0.0016), which could indicate a genetic propensity towards a raised intracellular production of topo IIα in these individuals. There was no direct correlation between chromosomal radiosensitivity and topo IIα level for individual samples either in the breast cancer cohort or in controls. However, a comparison between control and breast cancer samples shows a higher mean topo IIα level in breast cancer samples that correlates with the elevated mean chromatid break frequency seen in these patient samples. We found no meaningful correlations between either chromatid break frequency or topo IIα level and either tumour grade or hormone status. We conclude that elevated intracellular topo IIα level is likely to be a significant factor in determining the chromosomal response of stimulated T-lymphocytes from certain breast cancer cases.

The peculiarities of polymorphism of XPD and XRCC1 repair genes in cells of down and Ehlers-Danlo syndrome patients characterized by increased radiosensitivity

Codon 312 and 751 polymorphisms ofXPD gene and codon 399 polymorphism of XRCC1 gene of peripheral blood lymphocytes in patients with Down syndrome (DS) (46 individuals), Ehlers-Danlo syndrome (EDS) (47 individuals) and in a group of healthy donors (control) (40 individuals) have been studied. Frequency of XPD genotype (G312G) coding for the most effectively functioning form of XPD protein was lower in patients with DS (26%) than in a group of healthy donors (42.5%) (p = 0.035), whereas no significant differences with the control were revealed for this codon in patients with EDS. No patients with XPD genotype (C751C) (p = 0.036) were revealed in a group of EDS patients, while this genotype was found in 16% of a group of healthy donors and in 17% of patients with DS. The trend of XRCC1 genotype frequency reduction (A399A) (p = 0.085) in EDS patients (3.9%) compared with the group of healthy donors (13.5%) and DS patients (13.3%) has been obtained. These data show that polymorphisms of the excision repair genes under study are accompanied by an elevated individual radio sensitivity in patients with DS. Genes investigated (their polymorphic variants) did not participate in the mechanisms for radio sensitive phenotype formation in EDS patients.

Radiation skin injury caused by percutaneous coronary intervention, report of 3 cases

Radiation induced skin injuries in interventional procedures started to be reported in early 1990s and are still appearing [1–9]. A number of reasons have been cited e.g. complexity of procedure and equipment, lack of awareness on the part of interventionist, complexity of procedure, prolonged or multiple procedures, lack of monitoring of radiation dose, unnecessary body part in the beam and thick body mass in the beam. In rare situations patients with elevated radiosensitivity are encountered resulting in radiation injury. Restoration of patency of a chronic total occlusion (CTO) is typically associated with prolonged fluoroscopy exposure and there is higher potential for radiation injury. Three cases of CTO involving multiple PCIs and resulting in skin injuries occurring in 2009 alone are reported here. This is the first report of radiation induced skin injuries in Thailand from fluoroscopically guided PCI. Tables 1 and 2 provide overall and detailed information about each case in terms of radiation exposure and relevant details. Case 1, 67-y-old man, underwent 3 PCIs for CTO. Skin lesion of National Cancer Institute (NCI) grade toxicity of 1 [9] was detected by nurse 6 weeks after 3rd PCI when the patient was being prepared for the PCI after failed CTO in last visit. He didn't know exactly when it happened but realized about 3 weeks after PCI. It started with erythematous patch in the back close to right shoulder (Fig. 1). It healed without ulcer, however, hyperpigmentation has persisted for the least 7 months. Because his symptom of chest pain was of mild