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  • radiotherapy  (15)
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  • 1
    Keywords: treatment ; ASSOCIATION ; polymorphism ; POLYMORPHISMS ; single nucleotide polymorphism ; SUSCEPTIBILITY ; VARIANTS ; SKIN ; mechanisms ; prevention ; HEALTH ; PROMOTER ; BREAST ; breast cancer ; BREAST-CANCER ; cancer prevention ; smoking ; SNP ; REPAIR ; WOMEN ; LYMPHOCYTES ; DAMAGE ; GENOTYPES ; cancer risk ; CANCER-PATIENTS ; INDIVIDUALS ; case-control studies ; DNA-DAMAGE ; CANCER PATIENTS ; SUSCEPTIBILITY GENE ; BODY ; RISK ; GENE ; ENZYMES ; DISEASE ; lung cancer ; LUNG-CANCER ; PATIENT ; MECHANISM ; DNA ; TUMORS ; validation ; DRUG ; RNA ; GENES ; THERAPY ; VITRO ; LUNG ; COMBINATION ; CANCER ; EXPRESSION ; IN-VITRO ; CELLS ; CELL ; tumor ; AGENTS ; radiotherapy ; NSCLC ; CANCER-RISK ; cancer research ; RNA EXPRESSION ; ENZYME ; case control studies ; analysis ; GENOTYPE ; PROFILES ; single-nucleotide ; development ; PROMOTER POLYMORPHISM ; XRCC1 ; VARIANT ; WEIGHT ; SINGLE NUCLEOTIDE POLYMORPHISMS ; SNPs ; case-control study ; GEMCITABINE ; CAPACITY ; DEFICIENCY ; small cell lung cancer ; AGENT ; SINGLE ; DNA repair ; MPO ; APE1
    Abstract: Cells in the body are permanently attacked by DNA-reactive species, both from intracellular and environmental sources. Inherited and acquired deficiencies in host defense mechanisms against DNA damage (metabolic and DNA repair enzymes) can modify cancer susceptibility as well as therapy response. Genetic profiles should help to identify high-risk individuals who subsequently can be enrolled in preventive measures or treated by tailored therapy regimens. Some of our attempts to define such risk profiles are presented. Cancer susceptibility: Single nucleotide polymorphisms (SNPs) in metabolic and repair genes were investigated in a hospital-based lung cancer case-control study. When evaluating the risk associated with different genotypes for N-acetyltransferases (Wikman et al. 2001) and glutathione-S-transferases (Risch et al. 2001), it is mandatory to distinguish between the three major histological subtypes of lung tumors. A promoter polymorphism of the myeloperoxidase gene MPO was shown to decrease lung cancer susceptibility mainly in small cell lung cancer (SCLC) (Dally et al. 2002). The CYP3A4*1B allele was also linked to an increased SCLC risk and in smoking women increased the risk of lung cancer eightfold (Dally et al. 2003b). Polymorphisms in DNA repair genes were shown to modulate lung cancer risk in smokers, and reduced DNA repair capacity elevated the disease risk (Rajaee-Behbahani et al. 2001). Investigations of several DNA repair gene variants revealed that lung cancer risk was only moderately affected by a single variant but was enhanced up to approximately threefold by specific risk allele combinations (Popanda et al. 2004). Therapy response: Inter-individual differences in therapy response are consistently observed with cancer chemotherapeutic agents. Initial results from ongoing studies showed that certain polymorphisms in drug transporter genes (ABCB1) differentially affect response outcome in histological subgroups of lung cancer. Stronger beneficial effects were seen in non-small cell lung cancer (NSCLC) patients following gemcitabine and in SCLC patients following etoposide-based treatment. Several DNA repair parameters (polymorphisms, RNA expression, and DNA repair capacity) were measured in vitro in lymphocytes of patients before radiotherapy and correlated with the occurrence of acute side effects (radio-hypersensitivity). Our initial analysis of several repair gene variants in breast cancer patients (n = 446) who received radiotherapy revealed no association of single polymorphisms and the development of side effects (moist desquamation of the irradiated normal skin). The risk for this side effect was, however, strongly reduced in normal weight women carrying a combination of XRCC1 399Gln and APE1 148Glu alleles, indicating that these variants afford some protection against radio-hypersensitivity (Chang-Claude et al. 2005). Based on these data we conclude that specific metabolic and DNA repair gene variants can affect cancer risk and therapy outcome. Predisposition to hereditary cancer syndromes is dominated by the strong effects of some high-penetrance tumor susceptibility genes, while predisposition to sporadic cancer is influenced by the combination of multiple low-penetrance genes, of which as a major challenge, many disease-relevant combinations remain to be identified. Before translating these findings into clinical use and application for public health measures, large population-based studies and validation of the results will be required.
    Type of Publication: Book chapter
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  • 2
    Keywords: CANCER ; IRRADIATION ; radiotherapy ; Germany ; TOXICITY ; LUNG-CANCER ; RISK ; RISKS ; GENE ; GENES ; HYBRIDIZATION ; SURGERY ; radiation ; PATIENT ; DNA ; GENETIC POLYMORPHISMS ; SKIN ; ASSOCIATION ; polymorphism ; POLYMORPHISMS ; SUSCEPTIBILITY ; VARIANTS ; BREAST ; breast cancer ; BREAST-CANCER ; DESIGN ; DNA-REPAIR ; REPAIR ; DAMAGE ; PROBES ; CARRIERS ; CANCER PATIENTS ; body mass index ; NUCLEOTIDE EXCISION-REPAIR ; DNA repair ; radiation sensitivity ; ACID SUBSTITUTION VARIANTS ; radiosensitivity ; MASSES ; RE ; VARIANT ; CAPACITY ; CANCER SUSCEPTIBILITY ; XPD ; ALLELES ; INTERVAL ; DNA repair gene ; DNA repair genes ; GENETIC-POLYMORPHISM ; CARRIER ; GENOTYPE ; HAPLOTYPE
    Abstract: Purpose: Several DNA repair gene polymorphisms have been described, which affect DNA repair capacity and modulate cancer susceptibility. We evaluated the association of six polymorphisms in the DNA repair genes: XRCC1 (Arg(194) Trp, Arg(280)His, and Arg(399)GIn), APE1 (Asp(148)Glu), and XPD (Lys(751)Gln and Asp(312)Asn), with the risk of acute skin reactions following radiotherapy. Design: We conducted a prospective study of 446 female patients with breast cancer who received radiotherapy after breast-conserving surgery. Individual genetic polymorphisms were determined using melting point analysis of sequence-specific hybridization probes. The development of acute skin reactions (moist desquamation) associated with DNA repair gene polymorphisms was modeled using Cox proportional hazards, accounting for cumulative biologically effective radiation dose. Results: Overall, the development of acute toxicity, which presented in 77 patients, was not associated with the genetic variants studied, although the hazard ratios (HR) were generally below 1. Risks were however differential by body mass index. Among normal-weight patients only, both carriers of theAPE1 (148)Glu and the XRCC1 (399)Gln alleles had decreased risk of acute skin reactions after radiotherapy (HR, 0.49 and 0.51, respectively). The results for XRCC1 were confirmed by haplotype analysis. When considering joint effects, we observed that compared with homozygote carriers of the wild-type allele in both genes, the risk was most strongly reduced in carriers of both APE1 (148)Glu and XRCC1 (399)GIn alleles with normal weight [HR, 0.19; 95% confidence interval (95% CI), 0.06-0.56] but not in those with overweight (HR, 1.39; 95% CI, 0.56-3.45; P-interaction = 0-009). Conclusion: The XRCC1 (399)Gln or APE1 (148)Glu alleles may be protective against the development of acute side effects after radiotherapy in patients with normal weight
    Type of Publication: Journal article published
    PubMed ID: 16000577
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  • 3
    Keywords: radiotherapy ; SUSCEPTIBILITY ; DAMAGE ; MUTATIONS ; MAMMALIAN-CELLS ; OXIDATIVE STRESS ; METAANALYSIS ; SINGLE-NUCLEOTIDE POLYMORPHISMS ; GENOME-WIDE ASSOCIATION ; MITOCHONDRIAL-DNA
    Abstract: Base excision repair (BER) removes DNA damage induced by endogenous reactive oxygen species or ionizing radiation, important breast cancer risk factors. Genetic variation associated with impaired BER might thus increase breast cancer risk. Therefore, we assessed risk associations of 123 common single nucleotide polymorphisms (SNPs) in 19 BER genes in 1,639 postmenopausal breast cancer cases and 1,967 controls from the German population-based case-control study MARIE. SNPs were tagging SNPs representing genetic variation across the gene together with potentially functional SNPs. Risk associations were assessed using conditional logistic regression, adjusted for potential breast cancer risk factors. Significant associations between polymorphisms and breast cancer risk were found for one SNP in PARP2 and three SNPs in the mitochondrial DNA polymerase gamma, POLG. A SNP in the promoter region of POLG (rs2856268, A〉G) showed a protective effect for homozygous GG carriers (odds ratio 0.81, 95% confidence intervals 0.65-1.00). Joint analysis of an enlarged sample set and haplotype analysis supported the results for POLG. Quantification of POLG mRNA expression in lymphocytes of 148 breast cancer patients revealed higher mRNA levels for rs2856268 GG carriers (p value = 0.038). A luciferase promoter assay showed significant differences between constructs harboring the respective alleles. Taken together, our results suggest that genetic variation in the POLG promoter region affects DNA polymerase gamma levels in mitochondria. This could contribute to the reported increase in mitochondrial mutation frequency resulting in dysfunction and altered breast cancer risk. Risk effects and the functional impact of the POLG promoter variant require further confirmation.
    Type of Publication: Journal article published
    PubMed ID: 22684821
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  • 4
    Keywords: CANCER ; CELLS ; EXPRESSION ; IRRADIATION ; radiotherapy ; CELL ; Germany ; THERAPY ; TOXICITY ; COHORT ; RISK ; SURGERY ; radiation ; PATIENT ; DNA ; INDEX ; QUALITY ; SKIN ; treatment ; BREAST ; breast cancer ; BREAST-CANCER ; LESIONS ; RADIATION-THERAPY ; ASSAY ; WOMEN ; DNA-REPAIR ; REPAIR ; COMET ASSAY ; DAMAGE ; LYMPHOCYTES ; BEAM ; DNA-DAMAGE ; PARAMETERS ; CANCER-PATIENTS ; KINETICS ; body mass index ; DNA repair ; DNA repair capacity ; PERIPHERAL-BLOOD LYMPHOCYTES ; ATAXIA-TELANGIECTASIA ; HETEROZYGOTES ; INTRINSIC RADIOSENSITIVITY ; radiation tolerance,DNA repair capacity,breast neoplasms,body mass index
    Abstract: Background and purpose: Intrinsic and extrinsic factors can affect the occurrence of side effects of radiotherapy. The influence of therapy modalities, personal characteristics and individual DNA repair capacity on the risk of acute skin toxicity was thus evaluated.Materials and methods: In a prospective study of 478 female breast cancer patients receiving adjuvant radiotherapy of the breast after breast-conserving surgery, acute skin toxicity was documented systematically using a modified version of the common toxicity criteria. Prognostic personal and treatment characteristics were identified for the entire cohort. Individual DNA repair capacity was determined in a subgroup of 113 patients with alkaline comet assay using phytohemagglutinin stimulated lymphocytes. Using proportional hazards analysis to account for cumulative biologically effective radiation dose, the hazard for the development of acute skin reactions (moist desquamation) associated with DNA repair capacity was modeled.Results: Of the 478 participants, 84 presented with acute reactions by the end of treatment. Higher body mass index was significantly associated with an increased risk for acute reactions (hazard ratio = 1.09 per 1 kg/m(2)), adjusted for treating hospital and photon beam quality. The comet assay parameters examined, including background DNA damage in non-irradiated cells, DNA damage induced by 5 Gy, and DNA repair capacity, were not significantly associated with risk of acute skin toxicity.Conclusions: Higher BMI is predictive of acute skin toxicity, however, individual repair parameters as determined by the alkaline comet assay are not informative enough. More comprehensive analyses including late effects of radiotherapy and repair kinetics optimized for different radiation-induced DNA lesions are warranted. (C) 2003 Elsevier Ireland Ltd. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 14643951
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  • 5
    Keywords: APOPTOSIS ; CANCER ; IONIZING-RADIATION ; radiotherapy ; Germany ; IN-VIVO ; TOXICITY ; RISK ; RISKS ; GENE ; GENES ; HYBRIDIZATION ; SURGERY ; radiation ; PATIENT ; GENETIC POLYMORPHISMS ; SKIN ; ASSOCIATION ; polymorphism ; POLYMORPHISMS ; SUSCEPTIBILITY ; VARIANTS ; BREAST ; breast cancer ; BREAST-CANCER ; AGE ; WOMEN ; REPAIR ; p53 ; PCR ; DNA-DAMAGE ; Jun ; CANCER-PATIENTS ; BODY ; p21 ; CANCER PATIENTS ; TP53 ; MASS INDEX ; RE ; VARIANT ; WEIGHT ; OVERWEIGHT ; prospective ; prospective study ; INCREASED RISK ; acute toxicity ; female breast cancer ; CODON-31 ; REPOPULATION
    Abstract: p53 and p21 play an important role in G1/S checkpoint control in response to ionizing radiation. Yet the genetic polymorphisms in these genes have not been investigated with respect to radiation toxicity in patients. We therefore assessed the association between TP53 Arg72Pro, p53PIN3 and p21 Ser31Arg polymorphisms and the risk of acute skin toxicity after radiotherapy in a prospective study of 446 female breast cancer patients (average age 60.3 +/- 9.0 years) receiving radiotherapy after breast conserving surgery. The p53PIN3 polymorphism was determined by standard PCR, and TP53 Arg72Pro and p21 Ser31Arg polymorphisms using melting point analysis of sequence-specific hybridization probes. The development of acute skin toxicity (moist desquamation) was modelled using Cox proportional hazards, accounting for cumulative biologically effective radiation dose. Overall, the development of acute skin toxicity, which presented in 77 patients, was not significantly associated with the polymorphisms studied. Risks were however differential by body mass index. Compared to non-carriers, TP53 72Pro carriers had a non-significantly decreased risk of acute skin toxicity in normal weight women (hazard ratio 0.46, 95% CI, 0.18-1.18) but not in overweight patients (hazard ratio 1.07, 95% CI, 0.61-1.89) (p(interaction) =0.14). Haplotype analysis for the TP53 polymorphisms suggested that effect modification by TP53 72Pro may differ according to the p53PIN3 allele (p(interaction)=0.06). Furthermore, in TP53 72Pro carriers with p21 Ser/Ser genotype, the occurrence of acute toxicity was reduced in normal weight but not overweight patients. In conclusion, the TP53 72Pro variant may be associated with the development of acute skin toxicity after radiotherapy in patients with normal weight. Large clinical studies are needed to clearly confirm this association
    Type of Publication: Journal article published
    PubMed ID: 16331344
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  • 6
    Keywords: CANCER ; IRRADIATION ; radiotherapy ; Germany ; TOXICITY ; FOLLOW-UP ; INFORMATION ; COHORT ; LONG-TERM ; NEW-YORK ; RISK ; TISSUE ; SURGERY ; radiation ; TIME ; PATIENT ; RISK-FACTORS ; SKIN ; treatment ; ASSOCIATION ; BREAST ; breast cancer ; BREAST-CANCER ; DIFFERENCE ; AGE ; risk factors ; smoking ; RECURRENCE ; PROGNOSTIC-FACTORS ; MULTIVARIATE ; CANCER-PATIENTS ; PROGNOSTIC FACTORS ; NORMAL TISSUE ; side effects ; CANCER PATIENTS ; PROGNOSTIC FACTOR ; COMPLICATIONS ; TELANGIECTASIA ; fibrosis ; ONCOLOGY ; REGRESSION ; RE ; INCREASE ; prospective studies ; CARCINOGEN-DNA ADDUCTS ; PROGNOSTIC-FACTOR ; development ; INTERVAL ; analysis ; USA ; prospective ; prospective study ; odds ratio ; RISK-FACTOR ; LOGISTIC-REGRESSION ; nonsmokers ; REPAIR GENES ; CLINICAL RADIOSENSITIVITY ; CONSERVATION THERAPY ; CONSERVING THERAPY ; cosmesis ; EORTC BOOST ; late side effects ; NO BOOST TRIAL ; POSTMASTECTOMY RADIOTHERAPY ; RADIATION-INJURY
    Abstract: Radiotherapy after breast-conserving surgery is commonly applied to reduce recurrence of breast cancer but may cause acute and late side effects. To identify prognostic factors for the development of late toxicity after radiotherapy, we conducted a prospective study of breast cancer patients. We assessed late complications of radiotherapy and collected information on epidemiologic factors in a cohort of breast cancer patients who had received radiotherapy after breast-conserving surgery. Among 416 patients with complete follow-up data, the association between possible risk factors and development of late complications was evaluated using multivariate logistic regression analysis. After a median follow-up time of 51 months, 131 (31.4%) patients presented with telangiectasia and 28 (6.7%) patients with fibrosis. We observed a strong association between development of telangiectasia and fibrosis (p 〈 0.01). Increasing age of the patient was a risk factor for both telangiectasia and fibrosis (p-value for trend 〈 0.01 and 0.03, respectively). Patients with acute skin toxicity (odds ratio (OR) 1.8, 95% confidence interval (CI) 1.0-3.1) were at higher risk to develop telangiectasia. Long-term smoking was associated with a significant increase in risk of telangiectasia compared to non-smokers (OR 2.3, 95% CI 1.2-4.6). Our study revealed several factors other than radiation dose that may predispose to late complications following radiotherapy. Further understanding of differences in response to irradiation may advance individualized treatment and improve cosmetic outcome
    Type of Publication: Journal article published
    PubMed ID: 17221151
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  • 7
    Keywords: brain ; CANCER ; IRRADIATION ; radiotherapy ; tumor ; Germany ; PROSTATE ; THERAPY ; TOXICITY ; COHORT ; RISK ; GENE ; GENES ; TISSUE ; TUMORS ; validation ; radiation ; PATIENT ; MARKER ; RISK-FACTORS ; ASSOCIATION ; polymorphism ; POLYMORPHISMS ; BREAST ; MUTATION ; prostate cancer ; PROSTATE-CANCER ; MARKERS ; cancer risk ; RISK FACTOR ; HEAD ; NETHERLANDS ; NORMAL TISSUE ; NECK-CANCER ; brain tumor ; BRAIN-TUMORS ; head and neck cancer ; THERAPIES ; brain tumors ; RISK-FACTOR ; CANCERS ; CANCER-RISK ; GENOME-WIDE ASSOCIATION ; Genetic ; Genome-wide association studies ; cellular response ; CELLULAR-RESPONSE ; BRAIN-TUMOR
    Abstract: Radiotherapy is an important weapon in the treatment of cancer, but adverse reactions developing in the co-irradiated normal tissue can be a threat for patients. Early reactions might disturb the usual application schedule and limit the radiation dose. Late appearing and degenerative reactions might reduce or destroy normal tissue function. Genetic markers conferring the ability to identify hyper-sensitive patients in advance would considerably improve therapy. Association studies on genetic variation and occurrence of side effects should help to identify such markers. This survey includes published studies and novel data from our own laboratory. It illustrates the presence of candidate polymorphisms in genes involved in the cellular response to irradiation which could be used as predictive markers for radiosensitivity in breast or prostate cancer patients. For other tumor types such as head and neck cancers or brain tumors, the available data are much more limited. In any case, further validation of these markers is needed in large patient cohorts with systematically recorded data on side effects and patient characteristics. Genetic variation contributing to radiosensitivity should be screened on a broader basis using newly developed, more comprehensive approaches such as genome-wide association studies
    Type of Publication: Journal article published
    PubMed ID: 19022265
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  • 8
    Keywords: CANCER ; CELLS ; EXPRESSION ; IN-VITRO ; IRRADIATION ; radiotherapy ; Germany ; THERAPY ; NEW-YORK ; RISK ; SURGERY ; radiation ; PATIENT ; DNA ; DONOR ; RISK-FACTORS ; INDUCTION ; SKIN ; fibroblasts ; SUSCEPTIBILITY ; BREAST ; breast cancer ; BREAST-CANCER ; RADIATION-THERAPY ; ASSAY ; DNA-REPAIR ; REPAIR ; REPRODUCIBILITY ; risk factors ; cancer risk ; COMET ASSAY ; DAMAGE ; LYMPHOCYTES ; DNA repair ; radiation sensitivity ; alkaline single-cell microgel electrophoresis assay ; CELLULAR RADIOSENSITIVITY ; CHROMOSOMAL RADIOSENSITIVITY ; DNA repair capacity ; DOUBLE-STRAND BREAKS ; IN-VITRO RADIOSENSITIVITY ; NORMAL-TISSUE RADIOSENSITIVITY ; PERIPHERAL-BLOOD LYMPHOCYTES ; radiation effects ; radiosensitivity ; TELANGIECTASIA
    Abstract: Purpose: Repair of radiation-induced DNA damage plays a critical role for both the susceptibility of patients to side effects after radiotherapy and their subsequent cancer risk. The study objective was to evaluate whether DNA repair data determined in vitro are correlated with the occurrence of acute side effects during radiotherapy. Methods and Materials: Breast cancer patients receiving radiation therapy after a breast- conserving surgery were recruited in a prospective epidemiologic study. As an indicator for clinical radiosensitivity, adverse reactions of the skin were recorded. Cryo-preserved lymphocytes from 113 study participants were gamma-irradiated with 5 Gy in vitro and analyzed using the alkaline comet assay. Reproducibility of the assay was determined by repeated analysis (n = 26) of cells from a healthy donor. A coefficient of variation of 0.3 was calculated. Results: The various parameters determined to characterize the individual DNA repair capacity showed large differences between patients. Eleven patients were identified with considerably enhanced DNA damage induction, and 7 patients exhibited severely reduced DNA repair capacity after 15 and 30 min. Six patients were considered as clinically radiosensitive, indicated by moist desquamation of the skin after a total radiation dose of about 50 Gy. Conclusions: Using the alkaline comet assay as described here, breast cancer patients were identified showing abnormal cellular radiation effects, but this repair deficiency corresponded only at a very limited extent to the acute radiation sensitivity of the skin. Because impaired DNA repair could be involved in the development of late irradiation effects, individuals exhibiting severely reduced DNA repair capacity should be followed for the development of late clinical symptoms. (C) 2003 Elsevier Science Inc
    Type of Publication: Journal article published
    PubMed ID: 12654430
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  • 9
    Keywords: CANCER ; EXPRESSION ; IN-VITRO ; IONIZING-RADIATION ; radiotherapy ; BLOOD ; Germany ; THERAPY ; TOXICITY ; RISK ; GENE ; GENES ; transcription ; radiation ; PATIENT ; RESPONSES ; DNA ; RISK-FACTORS ; PATTERNS ; DNA-REPAIR ; REPAIR ; risk factors ; prostate cancer ; PROSTATE-CANCER ; PCR ; DAMAGE ; LYMPHOCYTES ; PROBES ; DNA-DAMAGE ; CANCER-PATIENTS ; RT-PCR ; INTENSITY-MODULATED RADIOTHERAPY ; sensitivity ; CANCER PATIENTS ; PERIPHERAL-BLOOD ; DNA repair ; CONSTITUTIVE EXPRESSION ; NORMAL-TISSUE RADIOSENSITIVITY ; PERIPHERAL-BLOOD LYMPHOCYTES ; radiosensitivity ; CLUSTER ; BRCA2 ; GRADE ; CLUSTER-ANALYSIS ; LEVEL ; DNA damage ; cluster analysis ; PROFILES ; EXPRESSION PATTERNS ; CRITERIA ; HUMAN-CELLS ; prospective ; GAMMA-IRRADIATION ; RISK-FACTOR ; SKIN REACTIONS ; peripheral blood ; GENOTOXIC STRESS ; gene expression profiles ; radio-resistance
    Abstract: Purpose: Repair of radiation-induced DNA damage is believed to play a critical role in the development of adverse reactions in radiotherapy patients. Constitutive mRNA expression of repair genes was investigated in such patients to analyze whether expression patterns are predictive for therapy-related acute side effects. Materials and methods: Prostate cancer patients (n = 406) receiving intensity-modulated radiotherapy were recruited in a prospective epidemiological study. Adverse effects were monitored during therapy using common toxicity criteria. For expression analyses, samples from 58 patients were selected according to their observed grade of clinical side effects to radiotherapy. Expression profiles were generated from peripheral blood lymphocytes using customized cDNA-arrays which carried probes for 143 DNA repair or repair-related genes. In addition, expression of selected genes was confirmed by quantitative real-time reverse transcription PCR (RT-PCR). Constitutive mRNA expression profiles were analyzed for predicting acute clinical radiosensitivity or radio-resistance. Results: Cluster analysis identified 19 differentially expressed genes. Many of these genes are involved in DNA double strand break repair. Expression levels of these genes differed up to 7-fold from the mean of all patients whereas expression levels of housekeeping genes varied only up to 2-fold. High expression of the identified genes was associated with a lack of clinical radiation sensitivity thus indicating radio-resistance. Conclusions: Constitutive expression of DNA repair-related genes may affect the development of acute side effects in radiotherapy patients, and high expression levels of these genes seem to support protection from adverse reactions
    Type of Publication: Journal article published
    PubMed ID: 16966187
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  • 10
    Keywords: CANCER ; CELLS ; EXPRESSION ; IN-VITRO ; IONIZING-RADIATION ; radiotherapy ; CELL ; Germany ; PROSTATE ; TOXICITY ; VITRO ; COMMON ; RISK ; GENE ; GENES ; transcription ; radiation ; TIME ; PATIENT ; DNA ; RISK-FACTORS ; INDUCTION ; STRESS ; DNA-REPAIR ; REPAIR ; risk factors ; smoking ; prostate cancer ; PROSTATE-CANCER ; MODULATION ; PCR ; DAMAGE ; LYMPHOCYTES ; DNA-DAMAGE ; CANCER-PATIENTS ; side effects ; CANCER PATIENTS ; real-time PCR ; NUCLEOTIDE EXCISION-REPAIR ; DNA repair ; NORMAL-TISSUE RADIOSENSITIVITY ; PERIPHERAL-BLOOD LYMPHOCYTES ; radiosensitivity ; ONCOLOGY ; GRADE ; quantitative RT-PCR ; REAL-TIME ; development ; ionizing radiation ; DAMAGE RECOGNITION ; LEVEL ; biomarker ; INTERVAL ; analysis ; CRITERIA ; BREAST-CANCER PATIENTS ; USA ; HUMAN-CELLS ; DNA damage response ; INCREASED RISK ; NEVER SMOKERS ; odds ratio ; RISK-FACTOR ; PREDICT ; quantitative ; REPAIR GENES ; LYMPHOBLASTOID-CELLS ; GROUP-C PROTEIN
    Abstract: Repair of radiation-induced DNA damage is believed to play a critical role in developing adverse reactions during radiotherapy. Ionizing radiation induces transcription of several DNA repair genes including XPC as a part of the p53-transmitted stress response. XPC gene induction was measured to analyze whether it predicts occurrence of therapy-related acute side effects. Prostate cancer patients (n = 406) receiving radiotherapy were monitored for development of acute adverse effects using common toxicity criteria. For gene induction analysis, lymphocytes from 99 patients were selected according to their observed grade of clinical side effects. Cells were irradiated in vitro with 5 Gy and analyzed after 4 hr for XPC gene induction using reverse transcription and quantitative real-time PCR. Analysis of modulation of XPC induction by personal, clinical or lifestyle factors was included. Inter-individual induction of XPC expression by ionizing radiation varied up to 20-fold (0.29-5.77) and was significantly higher in current or exsmokers than in never-smokers (p value: 0.008). Patients with XPC induction above the 90th percentile compared to those with lower induction levels were at increased risk of suffering from adverse reactions during radiotherapy (odds ratio 5.3, 95% confidence interval 1.2-24.5; adjusted for smoking). In summary, XPC mRNA levels induced by ionizing radiation were shown for the first time to be strongly affected by smoking and to be associated with an approximately 5-fold increased risk for developing acute side effects of radiotherapy. The predictive value of DNA damage-induced XPC levels as a possible biomarker for radiosensitivity has to be further investigated. (c) 2007 Wiley-Liss, Inc
    Type of Publication: Journal article published
    PubMed ID: 17657713
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