The epigenetic regulator RINF (CXXC5) maintains SMAD7 expression in human immature erythroid cells and sustains red blood cells expansion

The gene CXXC5, encoding a Retinoid-Inducible Nuclear Factor (RINF), is located within a region at 5q31.2 commonly deleted in myelodysplastic syndrome (MDS) and adult acute myeloid leukemia (AML). RINF may act as an epigenetic regulator and has been proposed as a tumor suppressor in hematopoietic malignancies. However, functional studies in normal hematopoiesis are lacking, and its mechanism of action is unknow. Here, we evaluated the consequences of RINF silencing on cytokineinduced erythroid differentiation of human primary CD34+ progenitors. We found that RINF is expressed in immature erythroid cells and that RINF-knockdown accelerated erythropoietin-driven maturation, leading to a significant reduction (~45%) in the number of red blood cells (RBCs), without affecting cell viability. The phenotype induced by RINF-silencing was TGFβ-dependent and mediated by SMAD7, a TGFβ- signaling inhibitor. RINF upregulates SMAD7 expression by direct binding to its promoter and we found a close correlation between RINF and SMAD7 mRNA levels both in CD34+ cells isolated from bone marrow of healthy donors and MDS patients with del(5q). Importantly, RINF knockdown attenuated SMAD7 expression in primary cells and ectopic SMAD7 expression was sufficient to prevent the RINF knockdowndependent erythroid phenotype. Finally, RINF silencing affects 5’-hydroxymethylation of human erythroblasts, in agreement with its recently described role as a Tet2- anchoring platform in mouse. Altogether, our data bring insight into how the epigenetic factor RINF, as a transcriptional regulator of SMAD7, may fine-tune cell sensitivity to TGFβ superfamily cytokines and thus play an important role in both normal and pathological erythropoiesis

Activation des voies PI3K/AKT et mTOR dans les LAM (thérapeutiques ciblées et Implication des facteurs de transcription FOXO dans la leucémogenèse)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Dérégulation des voies de signalisation P13K/Akt et mTOR dans les Leucémies Aigües Myéloïdes

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Ferroptose et cancer

La ferroptose est un processus conduisant à la mort de la cellule avec, pour évènement final, l’accumulation létale de lipides peroxydés. Le fer libre intracellulaire est au centre des réactions entraînant la formation de ces lipides peroxydés. Un système antioxydant dédié à la détoxification de ces lipides permet de prévenir la mort cellulaire. Le processus de ferroptose est impliqué dans un grand nombre de maladies, notamment dans la pathogénie des maladies neurodégénératives et infectieuses et du cancer. Nous présentons dans cette revue les principaux acteurs cellulaires qui contrôlent la ferroptose et proposons une synthèse des données actuelles impliquant ce processus dans le cancer

Solitary Plasmacytoma Treated by Lenalidomide-Dexamethasone in Combination with Radiation Therapy: Clinical Outcomes

International audiencePurpose: The study evaluates the results of the concurrent use of lenalidomide-dexamethasone with intensity modulated radiation therapy (IMRT) for solitary plasmacytoma in terms of toxicity and outcome. Methods and Materials: Forty-six patients were treated for histologically proven solitary plasmacytoma (SP) between June 2007 and June 2018 in our Department (Curie Institute, Paris, France). All patients received IMRT. The median total dose was 40 Gy (range, 40-46). Prescription of concurrent lenalidomide-dexamethasone with radiation therapy was left to the discretion of the referring hematologist-oncologist and started the first day of radiation therapy for 4 cycles. Results: Twenty-seven solitary plasmacytoma were treated with IMRT alone and 19 with lenalidomide-dexamethasone in association with IMRT. At 5 years, the local control, multiple myeloma–free survival (MMFS), and progression-free survival (PFS) rates were 96.3%, 85.4%, and 60%. MMFS and PFS were significantly higher in the IMRT plus lenalidomide-dexamethasone group compared with IMRT alone group (100% vs 77.1%, P = .02 and 81.7% vs 48.4%, P = .047, respectively). No major toxicity was found in either group. Conclusions: Lenalidomide-dexamethasone in association with IMRT in the treatment of solitary plasmacytoma is safe and improves MMFS and PFS. Further prospective and comparative studies are needed to confirm these results

Flow cytometric quantification of all phases of the cell cycle and apoptosis in a two-color fluorescence plot.

An optimal technology for cell cycle analysis would allow the concomitant measurement of apoptosis, G0, G1, S, G2 and M phases in combination with cell surface phenotyping. We have developed an easy method in flow cytometry allowing this discrimination in an only two-color fluorescent plot. It is based on the concomitant use of 7-amino-actinomycin D and the antibodies anti-Ki67 and anti-phospho(Ser10)-histone H3, both conjugated to Alexa Fluor®488 to discriminate G0 and M phases, respectively. The method is particularly valuable in a clinical setting as verified in our laboratory by analyzing human leukemic cells from marrow samples or after exposure to cell cycle modifiers