Dissecting molecular mechanisms of resistance to NOTCH1-targeted therapy in T-cell acute lymphoblastic leukemia xenografts

Despite substantial progress in treatment of T-cell acute lymphoblastic leukemia (T-ALL), mortality remains relatively high, mainly due to primary or acquired resistance to chemotherapy. Further improvements in survival demand better understanding of T-ALL biology and development of new therapeutic strategies. The Notch pathway has been involved in the pathogenesis of this disease and various therapeutic strategies are currently under development, including selective targeting of NOTCH receptors by inhibitory antibodies. We previously demonstrated that the NOTCH1-specific neutralizing antibody OMP52M51 prolongs survival in TALL patient-derived xenografts bearing NOTCH1/FBW7 mutations. However, acquired resistance to OMP52M51 eventually developed and we used patient-derived xenografts models to investigate this phenomenon. Multi-level molecular characterization of T-ALL cells resistant to NOTCH1 blockade and serial transplantation experiments uncovered heterogeneous types of resistance, not previously reported with other Notch inhibitors. In one model, resistance appeared after 156 days of treatment, it was stable and associated with loss of Notch inhibition, reduced mutational load and acquired NOTCH1 mutations potentially affecting the stability of the heterodimerization domain. Conversely, in another model resistance developed after only 43 days of treatment despite persistent down-regulation of Notch signaling and it was accompanied by modulation of lipid metabolism and reduced surface expression of NOTCH1. Our findings shed light on heterogeneous mechanisms adopted by the tumor to evade NOTCH1 blockade and support clinical implementation of antibody-based target therapy for Notch-addicted tumors

A Systems Biology Approach to Characterize the Regulatory Networks Leading to Trabectedin Resistance in an In Vitro Model of Myxoid Liposarcoma

Trabectedin, a new antitumor compound originally derived from a marine tunicate, is clinically effective in soft tissue sarcoma. The drug has shown a high selectivity for myxoid liposarcoma, characterized by the translocation t(12;16)(q13; p11) leading to the expression of FUS-CHOP fusion gene. Trabectedin appears to act interfering with mechanisms of transcription regulation. In particular, the transactivating activity of FUS-CHOP was found to be impaired by trabectedin treatment. Even after prolonged response resistance occurs and thus it is important to elucidate the mechanisms of resistance to trabectedin. To this end we developed and characterized a myxoid liposarcoma cell line resistant to trabectedin (402-91/ET), obtained by exposing the parental 402-91 cell line to stepwise increases in drug concentration. The aim of this study was to compare mRNAs, miRNAs and proteins profiles of 402-91 and 402-91/ET cells through a systems biology approach. We identified 3,083 genes, 47 miRNAs and 336 proteins differentially expressed between 402-91 and 402-91/ET cell lines. Interestingly three miRNAs among those differentially expressed, miR-130a, miR-21 and miR-7, harbored CHOP binding sites in their promoter region. We used computational approaches to integrate the three regulatory layers and to generate a molecular map describing the altered circuits in sensitive and resistant cell lines. By combining transcriptomic and proteomic data, we reconstructed two different networks, i.e. apoptosis and cell cycle regulation, that could play a key role in modulating trabectedin resistance. This approach highlights the central role of genes such as CCDN1, RB1, E2F4, TNF, CDKN1C and ABL1 in both pre- and post-transcriptional regulatory network. The validation of these results in in vivo models might be clinically relevant to stratify myxoid liposarcoma patients with different sensitivity to trabectedin treatment

Shedding light on typical species : implications for habitat monitoring

Habitat monitoring in Europe is regulated by Article 17 of the Habitats Directive, which suggests the use of typical species to assess habitat conservation status. Yet, the Directive uses the term “typical” species but does not provide a definition, either for its use in reporting or for its use in impact assessments. To address the issue, an online workshop was organized by the Italian Society for Vegetation Science (SISV) to shed light on the diversity of perspectives regarding the different concepts of typical species, and to discuss the possible implications for habitat monitoring. To this aim, we inquired 73 people with a very different degree of expertise in the field of vegetation science by means of a tailored survey composed of six questions. We analysed the data using Pearson's Chi-squared test to verify that the answers diverged from a random distribution and checked the effect of the degree of experience of the surveyees on the results. We found that most of the surveyees agreed on the use of the phytosociological method for habitat monitoring and of the diagnostic and characteristic species to evaluate the structural and functional conservation status of habitats. With this contribution, we shed light on the meaning of “typical” species in the context of habitat monitoring

Estimating influence of environmental quality and management of channels on survival of a threatened endemic quillwort

Iso\uebtes malinverniana Ces. et De Not. is a narrow endemic quillwort occurring within channels used for rice fields water supply, in the lowland area of North Italy. The range of I. malinverniana is highly fragmented and in the last 10 years the whole population decreased by more than 80%. This strong decline is assumed to be mainly related to the intensification of agricultural practices, which led to decreasing water quality, alteration of flow regimes and mechanized management. In order to highlight which of these factors may affect population performance and fate (persistence vs. extinction) of the species, plant cover, density and leaf length were measured, and a range of water and sediment parameters were analyzed at the plot scale, within the extant populations and in eight historical sites where I. malinvarniana recently disappeared. At least 4 out of 11 populations, characterized by cover values never exceeding 15% and density hardly approaching 20 plants m 122, revealed scarce chance for survival, under current conditions. On the basis of discriminant analysis, nutrient enrichment did not result the main predictor of Iso\uebtes decline, as generally noticed for isoetids, since higher water nitrates, P, K and organic C content in the sediments were found in the sites where I. malinverniana showed the highest performance compared to sites of less viable populations. On the other hand, the high water depth, the strong increase of water flow during the rice growing season and the intensive mechanized management of channels, e.g. cutting of aquatic vegetation and dredging using excavators, were among the most important parameters explaining the disappearance of the species. Our findings may have useful implications for the conservation or restoration of I. malinverniana and other rare aquatic species occurring in running waters of lowland agricultural areas. Hydrological alterations and mechanized maintenance of channels should be restricted where the species still occurs, to improve population performance and seedling survival

Management of tracheal intubation in the respiratory intensive care unit by pulmonary physicians

Expert management of tracheal intubation has become fundamental to the routine practice of pulmonary physicians who work in respiratory intensive care units (ICUs). In Italy, tracheal intubation is not included as part of the training in respiratory medicine, and pulmonary physicians are usually dissuaded from managing intubations