RSK2 is a new Pim2 target with pro-survival functions in FLT3-ITD-positive acute myeloid leukemia.

Acute myeloid leukemia (AML) with the FLT3 internal tandem duplication (FLT3-ITD AML) accounts for 20-30% of AML cases. This subtype usually responds poorly to conventional therapies, and might become resistant to FLT3 tyrosine kinase inhibitors (TKIs) due to molecular bypass mechanisms. New therapeutic strategies focusing on resistance mechanisms are therefore urgently needed. Pim kinases are FLT3-ITD oncogenic targets that have been implicated in FLT3 TKI resistance. However, their precise biological function downstream of FLT3-ITD requires further investigation. We performed high-throughput transcriptomic and proteomic analyses in Pim2-depleted FLT3-ITD AML cells and found that Pim2 predominantly controlled apoptosis through Bax expression and mitochondria disruption. We identified ribosomal protein S6 kinase A3 (RSK2), a 90 kDa serine/threonine kinase involved in the mitogen-activated protein kinase cascade encoded by the RPS6KA3 gene, as a novel Pim2 target. Ectopic expression of an RPS6KA3 allele rescued the viability of Pim2-depleted cells, supporting the involvement of RSK2 in AML cell survival downstream of Pim2. Finally, we showed that RPS6KA3 knockdown reduced the propagation of human AML cells in vivo in mice. Our results point to RSK2 as a novel Pim2 target with translational therapeutic potential in FLT3-ITD AML.

Oncogenic FLT3-ITD supports autophagy via ATF4 in acute myeloid leukemia.

In acute myeloid leukemia (AML), internal tandem duplication mutations in the FLT3 tyrosine kinase receptor (FLT3-ITD) account for up to 25% of cases and are associated with a poor outcome. In order to better target this AML subtype, a comprehensive view of how FLT3-ITD impacts AML cell biology is required. Here, we found that FLT3-ITD expression increased basal autophagy in AML cells, and that both pharmacological and genetic inhibition of the receptor reduced autophagy in primary AML samples and cell lines. Conditional expression of shRNAs against key autophagy proteins demonstrated that autophagy is required for AML cell proliferation in vitro and for leukemic cells survival in a mouse model of xenograft. Importantly, autophagy inhibition also overcame FLT3 inhibitor resistance both in vitro and in vivo. The transcription factor ATF4 was identified as an essential actor of FLT3-ITD-induced autophagy. Cellular levels of ATF4 were highly dependent on FLT3-ITD activity, and downregulation of ATF4 inhibited autophagy-dependent AML cell proliferation and improved overall mouse survival similarly to autophagy inhibition. These results suggest that targeting autophagy or ATF4 in patients expressing FLT3 mutations may represent a novel promising and innovative therapeutic strategy for AML.

Is climate change a threat for water uses in the Mediterranean region? Results from a survey at local scale.

Water scarcity and water security are linked, not only through the direct effects of water shortages on each water users' access to water, but also because of water conflicts generated. Climate change is predicted to raise temperatures in the Mediterranean region and reduce rainfall, leading to a reduction in water yield and possibly worsening the situation of water resource shortages that Mediterranean regions are already experiencing. In its dissemination strategy, the EU FP7 CLIMB project addressed water security threats through an analysis of water uses and water use rivalries within a few target catchments distributed over the Mediterranean region. The present work explores whether climate change is locally perceived by stakeholders (water users and managers) as a key issue for their water uses and water security. Individual interviews, meetings, and compilation of questionnaires were conducted at five sites located in the Mediterranean region. The methodology permitted an analysis of water use and its evolution in the water management context, an identification of the state of awareness of local stakeholders and of the pressures on water use and water use rivalries, and a prioritization of water uses. Currently, the main response to increasing water demand in the Mediterranean region, while not yet considering climate change as a driving force, is a progressive externalization of water resources, with limits represented by national borders and technological possibilities. Overall, 'climate change' was not mentioned by stakeholders during both interviews and in answers to the questionnaires. Even the prospect of decreasing precipitation was not considered a relevant or threatening issue in the coming 20years. This confirms the need to continue all efforts to disseminate the state of knowledge on climate change impacts in the Mediterranean region, such as water scarcity, especially to local water managers, as initiated by various research programs of the European Commission.

A robust and rapid xenograft model to assess efficacy of chemotherapeutic agents for human acute myeloid leukemia.

Relevant preclinical mouse models are crucial to screen new therapeutic agents for acute myeloid leukemia (AML). Current in vivo models based on the use of patient samples are not easy to establish and manipulate in the laboratory. Our objective was to develop robust xenograft models of human AML using well-characterized cell lines as a more accessible and faster alternative to those incorporating the use of patient-derived AML cells. Five widely used AML cell lines representing various AML subtypes were transplanted and expanded into highly immunodeficient non-obese diabetic/LtSz-severe combined immunodeficiency IL2Rγc(null) mice (for example, cell line-derived xenografts). We show here that bone marrow sublethal conditioning with busulfan or irradiation has equal efficiency for the xenotransplantation of AML cell lines. Although higher number of injected AML cells did not change tumor engraftment in bone marrow and spleen, it significantly reduced the overall survival in mice for all tested AML cell lines. On the basis of AML cell characteristics, these models also exhibited a broad range of overall mouse survival, engraftment, tissue infiltration and aggressiveness. Thus, we have established a robust, rapid and straightforward in vivo model based on engraftment behavior of AML cell lines, all vital prerequisites for testing new therapeutic agents in preclinical studies.

The short form of RON is expressed in acute myeloid leukemia and sensitizes leukemic cells to cMET inhibitors.

Several receptor tyrosine kinases (TKs) are involved in the pathogenesis of acute myeloid leukemia (AML). Here, we have assessed the expression of the Recepteur d'Origine Nantais (RON) in leukemic cell lines and samples from AML patients. In a series of 86 AML patients, we show that both the full length and/or the short form (sf) of RON are expressed in 51% and 43% of cases, respectively. Interestingly, sfRON is not expressed in normal CD34+ hematopoietic cells and induces part of its oncogenic signaling through interaction with the Src kinase Lyn. sfRON-mediated signaling in leukemic cells also involves mTORC1, the proapoptotic bcl2-family member, BAD, but not the phosphatidylinositol 3-kinase/Akt pathway. Furthermore, the expression of sfRON was specifically downregulated by 5-azacytidine (AZA). Conversely, AZA could induce the expression of sfRON in sfRON-negative leukemic cells suggesting that the activity of this drug in AML and myelodysplastic syndromes could involve modulation of TKs. cMET/RON inhibitors exhibited an antileukemic activity exclusively in AML samples and cell lines expressing sfRON. These results might support clinical trials evaluating cMET/RON inhibitors in AML patients expressing sfRON.

Evaluation of a preoperative multimedia information program in surgical oncology.

AIM: We report on the design, validation and evaluation of a DVD for patient information in a department of surgical oncology. PATIENTS AND METHOD: DVDs provided the patient with information about the anatomy, surgical techniques and post-operative complications on digestive cancers, oral cavity and breast tumours. After surgery a questionnaire was sent to the patients in order to evaluate their level of satisfaction and opinion regarding the pre-operative information they had been given. RESULTS: One hundred and eight patients were invited to watch the DVD. Seventy-one percent of the patients considered that viewing the DVD had been positive and encouraging and 83% of all the patients would recommend its use. Among the 14 patients who experienced complications, only 21% declared having been well informed by the DVD and only 12% considered they were better prepared to face those complications. CONCLUSIONS: DVD based information systems are valuable and acceptable to patients, but the presentation of complications needs to be improved.