Abstract 4615: H2AX phosphorylation assays, gene expression and epigenomic profiles as markers in bladder cancer: an integrated approach
Authors: Pardini Barbara , Allione Alessandra , Guarrera Simonetta , Turinetto Valentina , Fiorito Giovanni , Viberti Clara , Russo Alessia , Vineis Paolo , Sacerdote Carlotta , Giachino Claudia , Matullo Giuseppe 
Published: August 2015

Bladder cancer (BC), which is the fourth most common malignancy among men in the Western world, has a typical aetiology characterized by a multistep carcinogenesis, reflecting that multiple lesions in the DNA are required for tumour development. DNA repair capacity (DRC) is a complex marker comprising the sum of several factors such as gene variants, gene expression, stability of gene products, and effect of inhibitors/stimulators and might account for different susceptibility of developing this cancer. Individuals with low DRC will tend to accumulate more damage than those who have a better ability to repair such damage. The identification of patients with particular DRC and at high-risk of BC and/or recurrence of the disease could help in personalizing both surveillance and treatment.

We aimed at studying the relationship between DRC evaluated by H2AX phosphorylation assays and BC, integrating gene expression and epigenetic profile data (methylation levels and microRNA expression) in cryopreserved lymphocytes from 159 BC cases and 159 controls matched by age and smoking habits.

We observed a significant association between γ-H2AX basal levels and H2AX dephosphorylation capacity and risk of BC recurrence. Patients with high basal DSB signaling had a better event-free survival (HR 0.35, 95% CI 0. 19-0.63, p = 0.0005). Additionally, there was an association when considering the percentage of dephosphorylation after 3h divided into two categories (above and under the calculated best cut-off). Interestingly, when compared with the lower category (“slow repair”), the other group (“fast repair”) had a better event-free survival (HR 0.41, 95%CI 0.23-0.72, p = 0.002). Our data suggest that γ-H2AX can be considered as a possible molecular biomarker to identify patients with a higher risk of BC recurrence.

A subgroup of cases and controls (39 and 44, respectively) was also analyzed for evaluating their gene expression (Illumina HumanHT-12 Expression BeadChip array) and methylation profile data (Illumina HumanMethylation450 BeadChip array). We found a set of CpG islands that were differentially methylated among cases and controls and a set of genes whose expression was deregulated among different subgroups (e.g. cases vs healthy controls, controls vs BC patients with muscle invasive tumor, etc).

We performed an integrated analysis on the genotype/phenotype correlation in the analysed BC cases and healthy controls provided with detailed description of the follow-up for response to therapy/recurrence/survival. This integrated approach will help in elucidating the role of DRC (and its determinants) as predictive and prognostic marker and to identify DNA repair phenotypic assays to be performed in blood cells as non-invasive predictive method. Results will be presented at the AACR Annual Meeting.

Citation Format: Barbara Pardini, Alessandra Allione, Simonetta Guarrera, Valentina Turinetto, Giovanni Fiorito, Clara Viberti, Alessia Russo, Paolo Vineis, Carlotta Sacerdote, Claudia Giachino, Giuseppe Matullo. H2AX phosphorylation assays, gene expression and epigenomic profiles as markers in bladder cancer: an integrated approach. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4615. doi:10.1158/1538-7445.AM2015-4615