Applicability of Gene Expression in Saliva as an Alternative to Blood for Biodosimetry and Prediction of Radiation-induced Health Effects

As the great majority of gene expression (GE) biodosimetry studies have been performed using blood as the preferred source of tissue, searching for simple and less-invasive sampling methods is important when considering biodosimetry approaches. Knowing that whole saliva contains an ultrafiltrate of blood and white blood cells, it is expected that the findings in blood can also be found in saliva. This human in vivo study aims to examine radiation-induced GE changes in saliva for biodosimetry purposes and to predict radiation-induced disease, which is yet poorly characterized. Furthermore, we examined whether transcriptional biomarkers in blood can also be found equivalently in saliva. Saliva and blood samples were collected in parallel from radiotherapy (RT) treated patients who suffered from head and neck cancer (n = 8) undergoing fractioned partial-body irradiations (1.8 Gy/fraction and 50-70 Gy total dose). Samples were taken 12-24 h before first irradiation and ideally 24 and 48 h, as well as 5 weeks after radiotherapy onset. Due to the low quality and quantity of isolated RNA samples from one patient, they had to be excluded from further analysis, leaving a total of 24 saliva and 24 blood samples from 7 patients eligible for analysis. Using qRT-PCR, 18S rRNA and 16S rRNA (the ratio being a surrogate for the relative human RNA/bacterial burden), four housekeeping genes and nine mRNAs previously identified as radiation responsive in blood-based studies were detected. Significant GE associations with absorbed dose were found for five genes and after the 2nd radiotherapy fraction, shown by, e.g., the increase of CDKN1A (2.0 fold, P = 0.017) and FDXR (1.9 fold increased, P = 0.002). After the 25th radiotherapy fraction, however, all four genes (FDXR, DDB2, POU2AF1, WNT3) predicting ARS (acute radiation syndrome) severity, as well as further genes (including CCNG1 [median-fold change (FC) = 0.3, P = 0.013], and GADD45A (median-FC = 0.3, P = 0.031)) appeared significantly downregulated (FC = 0.3, P = 0.01-0.03). A significant association of CCNG1, POU2AF1, HPRT1, and WNT3 (P = 0.006-0.04) with acute or late radiotoxicity could be shown before the onset of these clinical outcomes. In an established set of four genes predicting acute health effects in blood, the response in saliva samples was similar to the expected up- (FDXR, DDB2) or downregulation (POU2AF1, WNT3) in blood for up to 71% of the measurements. Comparing GE responses (PHPT1, CCNG1, CDKN1A, GADD45A, SESN1) in saliva and blood samples, there was a significant linear association between saliva and blood response of CDKN1A (R2 = 0.60, P = 0.0004). However, the GE pattern of other genes differed between saliva and blood. In summary, the current human in vivo study, (I) reveals significant radiation-induced GE associations of five transcriptional biomarkers in salivary samples, (II) suggests genes predicting diverse clinical outcomes such as acute and late radiotoxicity as well as ARS severity, and (III) supports the view that blood-based GE response can be reflected in saliva samples, indicating that saliva is a "mirror of the body" for certain but not all genes and, thus, studies for each gene of interest in blood are required for saliva.

Examining potential confounding factors in gene expression analysis of human saliva and identifying potential housekeeping genes

Isolation of RNA from whole saliva, a non-invasive and easily accessible biofluid that is an attractive alternative to blood for high-throughput biodosimetry of radiological/nuclear victims might be of clinical significance for prediction and diagnosis of disease. In a previous analysis of 12 human samples we identified two challenges to measuring gene expression from total RNA: (1) the fraction of human RNA in whole saliva was low and (2) the bacterial contamination was overwhelming. To overcome these challenges, we performed selective cDNA synthesis for human RNA species only by employing poly(A)+-tail primers followed by qRT-PCR. In the current study, this approach was independently validated on 91 samples from 61 healthy donors. Additionally, we used the ratio of human to bacterial RNA to adjust the input RNA to include equal amounts of human RNA across all samples before cDNA synthesis, which then ensured comparable analysis using the same base human input material. Furthermore, we examined relative levels of ten known housekeeping genes, and assessed inter- and intra-individual differences in 61 salivary RNA isolates, while considering effects of demographical factors (e.g. sex, age), epidemiological factors comprising social habits (e.g. alcohol, cigarette consumption), oral hygiene (e.g. flossing, mouthwash), previous radiological diagnostic procedures (e.g. number of CT-scans) and saliva collection time (circadian periodic). Total human RNA amounts appeared significantly associated with age only (P ≤ 0.02). None of the chosen housekeeping genes showed significant circadian periodicity and either did not associate or were weakly associated with the 24 confounders examined, with one exception, 60% of genes were altered by mouthwash. ATP6, ACTB and B2M represented genes with the highest mean baseline expression (Ct-values ≤ 30) and were detected in all samples. Combining these housekeeping genes for normalization purposes did not decrease inter-individual variance, but increased the robustness. In summary, our work addresses critical confounders and provides important information for the successful examination of gene expression in human whole saliva.

Analysis of DNA methylation and microRNA expression in NUT (nuclear protein in testis) midline carcinoma of the sinonasal tract: a clinicopathological, immunohistochemical and molecular genetic study

The aim of this study was a detailed clinicopathological investigation of sinonasal NUT midline carcinoma (NMC), including analysis of DNA methylation and microRNA (miRNA) expression. Three (5%) cases of NMC were detected among 56 sinonasal carcinomas using immunohistochemical screening and confirmed by fluorescence in situ hybridization. The series comprised 2 males and 1 female, aged 46, 60, and 65 years. Two tumors arose in the nasal cavity and one in the maxillary sinus. The neoplasms were staged pT1, pT3, and pT4a (all cN0M0). All patients were treated by radical resection with adjuvant radiotherapy. Two patients died 3 and 8 months after operation, but one patient (pT1 stage; R0 resection) experienced no evidence of disease at 108 months. Microscopically, all tumors consisted of infiltrating nests of polygonal cells with vesicular nuclei, prominent nucleoli and basophilic cytoplasm. Abrupt keratinization was present in only one case. Immunohistochemically, there was a diffuse expression of cytokeratin (CK) cocktail, CK7, p40, p63, and SMARCB1/INI1. All NMCs tested negative for EBV and HPV infection. Two NMCs showed methylation of RASSF1 gene. All other genes (APC, ATM, BRCA1, BRCA2, CADM1, CASP8, CD44, CDH13, CDKN1B, CDKN2A, CDKN2B, CHFR, DAPK1, ESR1, FHIT, GSTP1, HIC1, KLLN, MLH1a, MLH1b, RARB, TIMP3, and VHL) were unmethylated. All NMCs showed upregulation of miR-9 and downregulation of miR-99a and miR-145 and two cases featured also upregulation of miR-21, miR-143, and miR-484. In summary, we described three cases of sinonasal NMCs with novel findings on DNA methylation and miRNA expression, which might be important for new therapeutic strategies in the future.

Validating Baboon Ex Vivo and In Vivo Radiation-Related Gene Expression with Corresponding Human Data

The research for high-throughput diagnostic tests for victims of radio/nuclear incidents remains ongoing. In this context, we have previously identified candidate genes that predict risk of late-occurring hematologic acute radiation syndrome (HARS) in a baboon model. The goal of the current study was to validate these genes after radiation exposure in humans. We also examined ex vivo relative to in vivo measurements in both species and describe dose-response relationships. Eighteen baboons were irradiated in vivo to simulate different patterns of partial- or total-body irradiation (TBI), corresponding to an equivalent dose of 2.5 or 5 Sv. Human in vivo blood samples were obtained from patients exposed to different dose ranges: diagnostic computerized tomography (CT; 0.004-0.018 Sv); radiotherapy for prostate cancer (0.25-0.3 Sv); and TBI of leukemia patients (2 × 1.5 or 2 × 2 Sv, five patients each). Peripheral whole blood of another five baboons and human samples from five healthy donors were cultivated ex vivo and irradiated with 0-4 Sv. RNA was isolated pairwise before and 24 h after irradiation and converted into cDNA. Gene expression of six promising candidate genes found previously by us in a baboon model ( WNT3, POU2AF1, CCR7, ARG2, CD177, WLS), as well as three genes commonly used in ex vivo whole blood experiments ( FDXR, PCNA, DDB2) was measured using qRT-PCR. We confirmed the six baboon candidate genes in leukemia patients. However, expression for the candidate gene FDXR showed an inverse relationship, as it was downregulated in baboons and upregulated in human samples. Comparisons among the in vivo and ex vivo experiments revealed the same pattern in both species and indicated peripheral blood cells to represent the radiation-responsive targets causing WNT3 and POU2AF1 gene expression changes. CCR7, ARG2, CD177 and WLS appeared to be altered due to radiation-responsive targets other than the whole blood cells. Linear dose-response relationships of FDXR, WNT3 and POU2AF1 using human ex vivo samples corresponded with human in vivo samples, suggesting that ex vivo models for in vivo dose estimates can be used over a wide dose range (0.001-5 Sv for POU2AF1). In summary, we validated six baboon candidate genes in humans, but the FDXR measurements underscored the importance of independent assessments even when candidates from animal models have striking gene sequence homology to humans. Since whole blood cells represented the same radiation-responsive targets for FDXR, WNT3 and POU2AF1 gene expression changes, ex vivo cell culture models can be utilized for in vivo dose estimates over a dose range covering up to 3.5 log scales. These findings might be a step forward in the development of a gene expression-based high-throughput diagnostic test for populations involved in large-scale radio/nuclear incidents.

Quantitative Evaluation of the Benefit of Fiducial Image-Guidance for Prostate Cancer Intensity Modulated Radiation Therapy Using Daily Dose Volume Histogram Analysis

To quantitatively evaluate the extent to which fiducial-based image-guidance improves dose coverage of the target volume and sparing of critical organs for prostate cancer patients treated with intensity modulated radiotherapy (IMRT) and determination of planning margins by original approach of detailed daily dose volume histogram (DVH) and patient's position correction analysis. Sixty-two patients divided in two groups (clinical target volume (CTV) → planning target volume (PTV) margin 10 and 7 mm) were treated with IMRT using implanted fiducial markers. Each patient's treatment fraction was recalculated as it would have been treated without fiducial-guided positioning. For both plans (IGRT and non-IGRT), equivalent uniform doses (EUD), maximal and minimal doses for target volumes, normal tissue complication probability (NTCP), maximum and mean doses for organs at risk and the whole DVH differences were assessed. In the group with 10 mm margins, the only significant difference was worse rectal NTCP by 4.5%, but the CTV dose coverage remained at the same level. Recalculated plans with 7 mm margin could not achieve the prescribed target volume coverage, and the EUD decreased by 3.7 and 0.6 Gy for PTV and CTV, respectively. Desired CTV → PTV margin for non-IGRT plans should be no lower than 12 mm to guarantee 95% instances when delivered dose to CTV maintain as planned, for IGRT plans decrease this requirement to 2 mm. Prostate IMRT strategies involving margin reduction below 7 mm require image-guidance to maintain the planned dose coverage. Using fiducial-based image-guidance and large margins seems to be superfluous.

ATM and TGFB1 genes polymorphisms in prediction of late complications of chemoradiotherapy in patients with locally advanced cervical cancer

The purpose of our study was to evaluate a possible correlation between genetic polymorphisms in ATM and TGFB1 genes and late toxicity of chemoradiotherapy for locally advanced cervical cancer. Fifty five patients with FIGO stage IIB and higher without a disease recurrence with a mean follow up of 6 years were included. Late toxicity was assessed by EORTC/RTOG late toxicity criteria. Univariate and multivariate logistic regression model was used for statistical analysis. Degree of association between polymorphisms and late toxicity of chemotherapy was assessed on the basis of phi-coefficient (φ) as well. We did not find any association between 5557G>A polymorphism in the ATM gene or single TGFB1 polymorphisms and late toxicity. TGFB1 compound homozygosity (-1552delAGG, -509C>T, L10P) was a significant predictive factor of grade III-IV and any grade of complications in both univariate and multivariate logistic regression analyses and statistical significance of association between polymorphisms and late toxicity of chemoradiotherapy was confirmed also by the evaluation of phi-coefficient (φ). We conclude that haplotypes instead of single nucleotide polymorphic sites in the genes may better characterize the individual radiosensitivity.

Successful radiotherapy treatment of lacrimal gland infiltration in patient with Sjögren΄s syndrome

OBJECTIVE

To present a single case report on successful radiotherapy treatment of lacrimal gland infiltration in patient with Sjögren΄s syndrome.

BACKGROUND

Radiotherapy is occasionally used for the treatment of benign disorders. There is no report on use of radiotherapy for local treatment of the Sjögren΄s syndrome in the literature.

METHODS

Female patient with lacrimal gland involvement as a part of Sjögren΄s syndrome with diplopia and visus deterioration was treated by radiotherapy with eye shielding.

RESULTS

Regression of the infiltration with full restoration of visus and minimal acute radiation reaction was achieved.

CONCLUSION

A case report of successful use of local radiotherapy in the treatment of lacrimal gland affected by Sjögren΄s syndrome is presented (Fig. 3, Ref. 6). Full Text in PDF www.elis.sk.

Molecular predictive factors of outcome of radiotherapy in cervical cancer

Radical radiotherapy with concurrent cisplatin-based chemotherapy is an established treatment for cervical cancer patients with stage FIGO IIB and higher. The tumor control can be achieved in 40-80% of patients, the treatment is associated with the risk of late postiradiation complications in 10 - 15% of cases. Detection of the factors predictive for tumor control and late morbidity is a possible direction how to individualize radiotherapy dose and technique. The aim of our review is to summarize results of studies inquiring various molecular markers predicting tumor response to radiotherapy and a risk of late complications. A lot of candidate molecules were evaluated in histochemical studies: membrane receptors (EGFR, HER-2), cell cycle regulators (p53, p21), proliferative markers (Ki-67), hypoxia and angiogenetic factors (HIF, VEGF), HPV status, and others (COX-2), with promising results in some of them (HPV, HIF-1α, Ku80, ATM polymorphism). Microarray studies identified decades of genes with different expression in radiosensitive/radioresistant cervical tumors and sets of genes are able to comletely separate responding and nonresponding tumors, but these sets differ across studies. Further well designed studies will be necessary to achieve results matured for use in clinical practice.

High dose rate versus low dose rate brachytherapy in the treatment of tongue carcinoma - a radiobiological study

Low dose rate (LDR) brachytherapy is a well established treatment for the early stages of tongue cancer. High dose rate (HDR) afterloading devices have replaced LDR brachytherapy in many radiotherapy departments, but the effect and safety of HDR brachytherapy in comparison with LDR brachytherapy for interstitial applications is an unresolved question. The aim of our radiobiological study was to utilize dose volume histiograms from patients treated in our institution to simulate the risk of complication of LDR and HDR brachytherapy. Normal tissue complication probabilities (NTCP) of acute mucositis, late mucosal necrosis and osteoradionecrosis of two HDR brachytherapy schedules (18 x 3 Gy bid and 10 x 6 Gy bid) and of LDR brachytherapy with identical tumor control probability were compared using data from 8 brachytherapy applications. A linear quadratic (LQ) model was used to calculate the biologically equivalent doses, the effective volume method of Kutcher and Burman and Lyman's model was used to calculate NTCP. The Student's two-tailed test was used for statistical analysis. For 18 x 3 Gy bid the risk of acute mucositis and of late mucosal necrosis was 1.48 and 1.66 times higher with HDR in comparison with LDR brachytherapy. For 10 x 6 Gy bid the risk of acute mucositis, mucosal necrosis and osteoradionecrosis was 1.3, 3.44 and 13.18 times higher with HDR brachytherapy. All differences were statistically highly significant. Our radiobiological study supported the hypothesis that HDR has a higher risk of complication in comparison with LDR brachytherapy for the same tumor control probability.

KEYWORDS

tongue cancer, brachytherapy, low dose rate, high dose rate.