Arasin 2

The First joint meeting of the German DGDR (German Society for Research on DNA Repair) and the French SFTG (French Society of Genotoxicology) on DNA Repair was held in Toulouse, France, from September 15 to 19, 2007. It was organized by Lisa Wiesmüller and Bernard Salles together with the scientific committee consisting of Gilbert de Murcia, Jean-Marc Egly, Frank Grosse, Karl-Peter Hopfner, Georges Iliakis, Bernd Kaina, Markus Löbrich, Bernard Lopez, Daniel Marzin and Alain Sarasin. This report summarizes information presented by the speakers (invited lectures and oral communications) during the seven plenary sessions, which include (1) excision repair, (2) DNA repair and carcinogenesis, (3) double-strand break repair, (4) replication in repair and lesion bypass, (5) cellular responses to genotoxic stress, (6) DNA repair machinery within the chromatin context and (7) genotoxicology and testing. A total of 23 plenary lectures, 32 oral communications and 66 posters were presented in this rather intense 4 days meeting, which stimulated extensive discussions and highly interdisciplinary scientific exchanges among the approximately 250 participants.

Purpose: Total-body irradiation (TBI) is a major constituent of myeloablative conditioning regimens. The standard technique consists of 12 Gy in 6 fractions over a period of 3 days. The Standard-fractionation compAred to one-daily fRaction total body irrAdiation prior to tranSplant In LEUkemia patieNts (SARASIN) study aimed to compare standard fractionation with once-daily fractionation before transplant in leukemia. Methods and materials: We retrospectively compared TBI regimens delivered in 2993 patients from the European Society for Blood and Marrow Transplantation database, who underwent transplantation between 2000 and 2014 for acute lymphoblastic leukemia (ALL, n = 1729) or acute myeloid leukemia (AML, n = 1264). TBI was delivered as either 12 Gy in 6 fractions (group 1, considered the reference group; 1362 ALL and 857 AML patients), 9 to 12 Gy in 2 fractions (group 2, 173 ALL and 256 AML patients), or 12 Gy in 3 to 4 fractions (group 3, 194 ALL and 151 AML patients). Results: The median follow-up was 60 and 84 months in ALL and AML patients, respectively. At 5 years, the leukemia-free survival rate, overall survival rate, relapse incidence, and nonrelapse mortality rate were 46.6%, 50.4%, 28.8%, and 24.6%, respectively, in ALL patients and 46.6%, 48.9%, 29.7%, and 23.6%, respectively, in AML patients. In multivariate analyses, the outcomes of groups 2 and 3 were not statistically different from those in group 1. The cumulative incidence of secondary malignancies (SMs) was significantly higher in group 2 (7.2%; P < 10-6 for group 2 vs group 1). However, group 2 was not associated with an increase in SMs when we considered non-T-cell-depleted transplant patients. Conclusions: We showed that the 12-Gy fractionated TBI dose delivered either in 2 fractions or in 1 fraction per day over a period of 3 to 4 days resulted in nonsignificant differences in disease control and survival. However, 1-day fractionation may be associated with a higher risk of mucositis and hemorrhagic cystitis. The absence of a significant difference in the SM incidence in the non-T-cell-depleted group should be interpreted with caution in the context of a retrospective study design. Our findings are important to consider for radiation therapy department organization. In-depth analyses of other nonlethal toxicities and late effects are required.

While the major drivers of melanoma initiation, including activation of NRAS/BRAF and loss of PTEN or CDKN2A, have been identified, the role of key transcription factors that impose altered transcriptional states in response to deregulated signaling is not well understood. The POU domain transcription factor BRN2 is a key regulator of melanoma invasion, yet its role in melanoma initiation remains unknown. Here, in a BrafV600E PtenF/+ context, we show that BRN2 haplo-insufficiency promotes melanoma initiation and metastasis. However, metastatic colonization is less efficient in the absence of Brn2. Mechanistically, BRN2 directly induces PTEN expression and in consequence represses PI3K signaling. Moreover, MITF, a BRN2 target, represses PTEN transcription. Collectively, our results suggest that on a PTEN heterozygous background somatic deletion of one BRN2 allele and temporal regulation of the other allele elicits melanoma initiation and progression.