Iron and ferritin dependent ROS distribution impact Arabidopsis root

Iron and ferritin dependent ROS distribution impact Arabidopsis root. XVII Iron Symposium on Iron Nutrition and Interactions in Plant

Iron- and Ferritin-Dependent Reactive Oxygen Species Distribution: Impact on Arabidopsis Root System Architecture

International audienceIron (Fe) homeostasis is integrated with the production of Reactive Oxygen Species (ROS) whose distribution at the root tip participates in the control of root growth. Excess Fe increases ferritin abundance, enabling the storage of Fe which contributes to protection of plants against Fe-induced oxidative stress. AtFer1 and AtFer3 are the two ferritin genes expressed in the meristematic zone, pericycle and endodermis of the Arabidopsis thaliana (Arabidopsis) root, and it is in these regions that we observe Fe stained dots. This staining disappears in the triple fer1-3-4 ferritin mutant. Fe excess decreases primary root length in the same way in wild-type and in fer1-3-4 mutant. In contrast, the Fe mediated decrease of lateral root (LR) length and density is enhanced in fer1-3-4 plants due to a defect in LR emergence. We observe that this interaction between excess Fe, ferritin and RSA is in part mediated by the H2O2/O2 (.-) balance between the root cell proliferation and differentiation zones regulated by the UPB1 transcription factor. Further, meristem size is also decreased in response to Fe excess in ferritin mutant plants, implicating cell cycle arrest mediated by the ROS-activated SMR5/SMR7 cyclin-dependent kinase inhibitors pathway in the interaction between Fe and RSA

Prospective Multicenter Validation of the Detection of ALK Rearrangements of Circulating Tumor Cells for Noninvasive Longitudinal Management of Patients With Advanced NSCLC

International audienceIntroduction: Patients with advanced-stage NSCLC whose tumors harbor an ALK gene rearrangement benefit from treatment with multiple ALK inhibitors (ALKi). Approximately 30% of tumor biopsy samples contain insufficient tissue for successful ALK molecular characterization. This study evaluated the added value of analyzing circulating tumor cells (CTCs) as a surrogate to ALK tissue analysis and as a function of the response to ALKi.Methods: We conducted a multicenter, prospective observational study (NCT02372448) of 203 patients with stage IIIB/IV NSCLC across nine French centers, of whom 81 were ALK positive (immunohistochemistry or fluorescence in situ hybridization [FISH]) and 122 ALK negative on paraffin-embedded tissue specimens. Blood samples were collected at baseline and at 6 and 12 weeks after ALKi initiation or at disease progression. ALK gene rearrangement was evaluated with CTCs using immunocytochemistry and FISH analysis after enrichment using a filtration method.Results: At baseline, there was a high concordance between the detection of an ALK rearrangement in the tumor tissue and in CTCs as determined by immunocytochemistry (sensitivity, 94.4%; specificity 89.4%). The performance was lower for the FISH analysis (sensitivity, 35.6%; specificity, 56.9%). No significant association between the baseline levels or the dynamic change of CTCs and overall survival (hazard ratio = 0.59, 95% confidence interval: 0.24-1.5, p = 0.244) or progression-free survival (hazard ratio = 0.84, 95% confidence interval: 0.44-1.6, p = 0.591) was observed in the patients with ALK-positive NSCLC.Conclusions: CTCs can be used as a complementary tool to a tissue biopsy for the detection of ALK rearrangements. Longitudinal analyses of CTCs revealed promise for real-time patient monitoring and improved delivery of molecularly guided therapy in this population

Efficacy and Safety of Rovalpituzumab Tesirine Compared With Topotecan as Second-Line Therapy in DLL3-High SCLC: Results From the Phase 3 TAHOE Study

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