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Along with their role in the maintenance of nuclear architecture, nuclear lamins also control genomic stability, DNA damage repair, transcription, cell proliferation, differentiation and senescence. Recent reports reveal that prelamin A-processing defects play a role in cancer development by impacting on transcription of key players in the maintenance of the genome stability, including RAD51. Here, we performed a 'proof of concept' study evaluating the role of prelamin A and RAD51 expression in clinical outcome of cervical cancer patients. We analyzed biomarker expression by immunohistochemistry in tumor material from locally advanced cervical cancer (LACC) patients (n=66) and correlated data with clinicopathological parameters and with response to neoadjuvant chemoradiation (CT/RT). In LACC patients who underwent neoadjuvant CT/RT the percentage of cases showing high prelamin A levels was greater in patients who completely responded to treatment (25 of 40, 62.5%) than in patients with macroscopic residual tumor (6 of 26, 23.1%, p=0.0024). Conversely, patients showing high RAD51 expression were less likely to respond to treatment (14 of 26, 53.8%) than were those with low protein levels (12 of 40, 30%, p=0.072). Only prelamin A retained an independent role in predicting response to treatment (p=0.003), while RAD51 approached statistical significance (p=0.07). Notably, high RAD51 expression highly significantly predicted poor outcome, emerging as an independent prognostic factor for disease free survival (p=0.038), while approaching statistical significance for overall survival (p=0.09). Our findings provide a framework for future prospective studies investigating molecular predictors of response to neoadjuvant chemoradiotherapy in LACC patients., Competing Interests: CONFLICTS OF INTEREST The authors declare that they have no competing interest.

It has historically been accepted that incorrectly repaired DNA double strand breaks (DSBs) are the principal lesions of importance regarding mutagenesis, and long-term biological effects associated with ionizing radiation. However, radiation may also cause dysregulation of epigenetic processes that can lead to altered gene function and malignant transformation, and epigenetic alterations are important causes of miRNAs dysregulation in cancer.Patched1 heterozygous (Ptch1+/-) mice, characterized by aberrant activation of the Sonic hedgehog (Shh) signaling pathway, are a well-known murine model of spontaneous and radiation-induced medulloblastoma (MB), a common pediatric brain tumor originating from neural granule cell progenitors (GCPs). The high sensitivity of neonatal Ptch1+/- mice to radiogenic MB is dependent on deregulation of the Ptch1 gene function. Ptch1 activates a growth and differentiation programme that is a strong candidate for regulation through the non-coding genome. Therefore we carried out miRNA next generation sequencing in ex vivo irradiated and control GCPs, isolated and purified from cerebella of neonatal WT and Ptch1+/- mice. We identified a subset of miRNAs, namely let-7 family and miR-17~92 cluster members, whose expression is altered in GCPs by radiation alone, or by synergistic interaction of radiation with Shh-deregulation. The same miRNAs were further validated in spontaneous and radiation-induced MBs from Ptch1+/- mice, confirming persistent deregulation of these miRNAs in the pathogenesis of MB.Our results support the hypothesis that miRNAs dysregulation is associated with radiosensitivity of GCPs and their neoplastic transformation in vivo.

Mutations in DNA repair pathways are frequent in human cancers. Hence, gaining insights into the interaction of DNA repair genes is key to development of novel tumor-specific treatment strategies. In this study, we tested the functional relationship in development and oncogenesis between the homologous recombination (HR) factor Rad54 and Parp-1 , a nuclear enzyme that plays a multifunctional role in DNA damage signaling and repair. We introduced single or combined Rad54 and Parp-1 inactivating germline mutations in Ptc1 heterozygous mice, a well-characterized model of medulloblastoma, the most common malignant pediatric brain tumor. Our study reveals that combined inactivation of Rad54 and Parp-1 causes a marked growth delay culminating in perinatallethality, providing for the first time evidence of synthetic lethal interactions between Rad54 and Parp-1 in vivo . Although the double mutation hampered investigation of Rad54 and Parp-1 interactions in cerebellum tumorigenesis, insights were gained by showing accumulation of endogenous DNA damage and increased apoptotic rate in granule cell precursors (GCPs). A network-based approach to detect differential expression of DNA repair genes in the cerebellum revealed perturbation of p53 signaling in Rad54 -/- / Parp-1 -/- / Ptc1 +/- , and MEFs from combined Rad54/Parp-1 mutants showed p53/p21-dependent typical senescent features. These findings help elucidate the genetic interplay between Rad54 and Parp-1 by suggesting that p53/p21-mediated apoptosis and/or senescence may be involved in synthetic lethal interactions occurring during development and inhibition of tumor growth., Competing Interests: CONFLICTS OF INTEREST The authors declare that they have no conflict of interest.