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Biomarkers with relevance for loco‐regional therapy are needed in human papillomavirus negative aka HPV(−) head and neck squamous cell carcinoma (HNSCC). Based on the premise that DNA methylation pattern is highly conserved, we sought to develop a reliable and robust methylome‐based classifier identifying HPV(−) HNSCC patients at risk for loco‐regional recurrence (LR) and all‐event progression after postoperative radiochemotherapy (PORT‐C). The training cohort consisted of HPV‐DNA negative HNSCC patients (n = 128) homogeneously treated with PORT‐C in frame of the German Cancer Consortium—Radiation Oncology Group (DKTK‐ROG) multicenter biomarker trial. DNA Methylation analysis was performed using Illumina 450 K and 850 K‐EPIC microarray technology. The performance of the classifier was integrated with a series of biomarkers studied in the training set namely hypoxia‐, 5‐microRNA (5‐miR), stem‐cell gene‐expression signatures and immunohistochemistry (IHC)‐based immunological characterization of tumors (CD3/CD8/PD‐L1/PD1). Validation occurred in an independent cohort of HPV(−) HNSCC patients, pooled from two German centers (n = 125). We identified a 38‐methylation probe‐based HPV(−) Independent Classifier of disease Recurrence (HICR) with high prognostic value for LR, distant metastasis and overall survival (P < 10−9). HICR remained significant after multivariate analysis adjusting for anatomical site, lymph node extracapsular extension (ECE) and size (T‐stage). HICR high‐risk tumors were enriched for younger patients with hypoxic tumors (15‐gene signature) and elevated 5‐miR score. After adjustment for hypoxia and 5‐miR covariates, HICR maintained predicting all endpoints. HICR provides a novel mean for assessing the risk of LR in HPV(−) HNSCC patients treated with PORT‐C and opens a new opportunity for biomarker‐assisted stratification and therapy adaptation in these patients. [ABSTRACT FROM AUTHOR]

Breast cancer is the second leading cause of cancer death among women worldwide and besides life style, age and genetic risk factors, exposure to ionizing radiation is known to increase the risk for breast cancer. Further, DNA copy number alterations (CNAs), which can result from radiation‐induced double‐strand breaks, are frequently occurring in breast cancer cells. We set out to identify a signature of CNAs discriminating breast cancers from radiation‐exposed and non‐exposed female patients. We analyzed resected breast cancer tissues from 68 exposed female Chernobyl clean‐up workers and evacuees and 68 matched non‐exposed control patients for CNAs by array comparative genomic hybridization analysis (aCGH). Using a stepwise forward–backward selection approach a non‐complex CNA signature, that is, less than ten features, was identified in the training data set, which could be subsequently validated in the validation data set (p value < 0.05). The signature consisted of nine copy number regions located on chromosomal bands 7q11.22‐11.23, 7q21.3, 16q24.3, 17q21.31, 20p11.23‐11.21, 1p21.1, 2q35, 2q35, 6p22.2. The signature was independent of any clinical characteristics of the patients. In all, we identified a CNA signature that has the potential to allow identification of radiation‐associated breast cancer at the individual level. [ABSTRACT FROM AUTHOR]

Ionizing radiation is a well-recognized risk factor for the development of breast cancer. However, it is unknown whether radiation-specific molecular oncogenic mechanisms exist. We investigated post-Chernobyl breast cancers from radiation-exposed female clean-up workers and nonexposed controls for molecular changes. Radiation-associated alterations identified in the discovery cohort ( n = 38) were subsequently validated in a second cohort ( n = 39). Increased expression of hsa-miR-26b-5p was associated with radiation exposure in both of the cohorts. Moreover, downregulation of the TRPS1 protein, which is a transcriptional target of hsa-miR-26b-5p, was associated with radiation exposure. As TRPS1 overexpression is common in sporadic breast cancer, its observed downregulation in radiation-associated breast cancer warrants clarification of the specific functional role of TRPS1 in the radiation context. For this purpose, the impact of TRPS1 on the transcriptome was characterized in two radiation-transformed breast cell culture models after siRNA-knockdown. Deregulated genes upon TRPS1 knockdown were associated with DNA-repair, cell cycle, mitosis, cell migration, angiogenesis and EMT pathways. Furthermore, we identified the interaction partners of TRPS1 from the transcriptomic correlation networks derived from gene expression data on radiation-transformed breast cell culture models and sporadic breast cancer tissues provided by the TCGA database. The genes correlating with TRPS1 in the radiation-transformed breast cell lines were primarily linked to DNA damage response and chromosome segregation, while the transcriptional interaction partners in the sporadic breast cancers were mostly associated with apoptosis. Thus, upregulation of hsa-miR-26b-5p and downregulation of TRPS1 in radiation-associated breast cancer tissue samples suggests these molecules representing radiation markers in breast cancer. [ABSTRACT FROM AUTHOR]