The presence of two tightly bound zn<SUP>2+</SUP> ions is essential for the structural and functional integrity of yeast RNA polymerase II

DNA-dependent RNA polymerases (RNApol) are Zn2+ metalloproteins where the Zn2+ ion plays both catalytic and structural roles. Although the ubiquitous presence of Zn2+ with the RNApol from eukaryotes had already been established, the exact stoichiometry of Zn2+ ion(s) per mole enzyme is not well documented, and its role in enzymatic function remains elusive. We show here that RNApolII from Saccharomyces cerevisiae has two Zn2+ ions tightly associated with it which are necessary for its transcriptional activity. Upon prolonged dialysis against 10 mM EDTA for 4-5 h, the enzyme loses one Zn2+, as well as partial activity. However, Zn2+ can be added back to the enzyme, but without recovering its total activity. 5 mM orthophenanthroline (OP) removes one Zn2+ within 2 h; the enzyme, however, cannot be reconstituted back with Zn2+. Circular dichroism (CD) studies showed that the conformation of the native enzyme is unique and cannot be reproduced with Zn2+-reconstituted RNApolII. Similarly, the rate of abortive synthesis of a dinucleotide product over a non-specific template is faster when catalyzed by two Zn2+-native enzymes. Zn2+-reconstituted RNApolII or one Zn2+-RNApolII showed a slower abortive synthesis rate. 65Zn2+-blotting experiments indicated that the removal of one Zn2+ from the enzyme destroys the Zn2+-binding ability of the larger subunits of yeast RNApolII. In order to check whether the presence of Zn2+ ions has any effect on substrate recognition, we followed the binding of (&#947; -AmNS)UTP, a fluorescent substrate analog to RNApol||. It was observed that OP-treated enzyme showed non-specific substrate recognition, whereas two Zn2+-native RNApol binds substrate at a single site

ΔNp63 induces β-catenin nuclear accumulation and signaling

AbstractThe P53 homolog p63 encodes multiple proteins with transactivating, apoptosis-inducing, and oncogenic activities. We showed that p63 is amplified and that ΔNp63 isotypes are overexpressed in squamous cell carcinoma (SCC) and enhance oncogenic growth in vitro and in vivo. Moreover, p53 associated with ΔNp63α and mediated its degradation. Here, we report that ΔNp63 associates with the B56α regulatory subunit of protein phosphatase 2A (PP2A) and glycogen synthase kinase 3β (GSK3β), leading to a dramatic inhibition of PP2A-mediated GSK3β reactivation. The inhibitory effect of ΔNp63 on GSK3β mediates a decrease in phosphorylation levels of β-catenin, which induces intranuclear accumulation of β-catenin and activates β-catenin-dependent transcription. Our results suggest that ΔNp63 isotypes act as positive regulators of the β-catenin signaling pathway, providing a basis for their oncogenic properties

DeltaNp63 induces beta-catenin nuclear accumulation and signaling.

The P53 homolog p63 encodes multiple proteins with transactivating, apoptosis-inducing, and oncogenic activities. We showed that p63 is amplified and that DeltaNp63 isotypes are overexpressed in squamous cell carcinoma (SCC) and enhance oncogenic growth in vitro and in vivo. Moreover, p53 associated with DeltaNp63alpha and mediated its degradation. Here, we report that DeltaNp63 associates with the B56alpha regulatory subunit of protein phosphatase 2A (PP2A) and glycogen synthase kinase 3beta (GSK3beta), leading to a dramatic inhibition of PP2A-mediated GSK3beta reactivation. The inhibitory effect of DeltaNp63 on GSK3beta mediates a decrease in phosphorylation levels of beta-catenin, which induces intranuclear accumulation of beta-catenin and activates beta-catenin-dependent transcription. Our results suggest that DeltaNp63 isotypes act as positive regulators of the beta-catenin signaling pathway, providing a basis for their oncogenic properties

Prospective subgroup analyses of the randomized MCL-002 (SPRINT) study : lenalidomide versus investigator's choice in relapsed or refractory mantle cell lymphoma

International audienceIn the mantle cell lymphoma (MCL)-002 study, lenalidomide demonstrated significantly improved median progression-free survival (PFS) compared with investigator's choice (IC) in patients with relapsed/refractory MCL. Here we present the long-term follow-up data and results of preplanned subgroup exploratory analyses from MCL-002 to evaluate the potential impact of demographic factors, baseline clinical characteristics and prior therapies on PFS. In MCL-002, patients with relapsed/refractory MCL were randomized 2:1 to receive lenalidomide (25 mg/day orally on days 1-21; 28-day cycles) or single-agent IC therapy (rituximab, gemcitabine, fludarabine, chlorambucil or cytarabine). The intent-to-treat population comprised 254 patients (lenalidomide, n = 170; IC, n = 84). Subgroup analyses of PFS favoured lenalidomide over IC across most characteristics, including risk factors, such as high MCL International Prognostic Index score, age ≥65 years, high lactate dehydrogenase (LDH), stage III/IV disease, high tumour burden, and refractoriness to last prior therapy. By multivariate Cox regression analysis, factors associated with significantly longer PFS (other than lenalidomide treatment) included normal LDH levels (P < 0·001), nonbulky disease (P = 0·045), <3 prior antilymphoma treatments (P = 0·005), and ≥6 months since last prior treatment (P = 0·032). Overall, lenalidomide improved PFS versus single-agent IC therapy in patients with relapsed/refractory MCL, irrespective of many demographic factors, disease characteristics and prior treatment history

Lenalidomide versus investigator's choice in relapsed or refractory mantle cell lymphoma (MCL-002; SPRINT): A phase 2, randomised, multicentre trial

none25siBACKGROUND: Lenalidomide, an immunomodulatory drug with antineoplastic and antiproliferative effects, showed activity in many single-group studies in relapsed or refractory mantle cell lymphoma. The aim of this randomised study was to examine the efficacy and safety of lenalidomide versus best investigator's choice of single-agent therapy in relapsed or refractory mantle cell lymphoma. METHODS: The MCL-002 (SPRINT) study was a randomised, phase 2 study of patients with mantle cell lymphoma aged 18 years or older at 67 clinics and academic centres in 12 countries who relapsed one to three times, had Eastern Cooperative Oncology Group performance status of 0-2, at least one measurable lesion to be eligible, and who were ineligible for intensive chemotherpy or stem-cell transplantation. Using a centralised interactive voice response system, we randomly assigned (2:1) patients in a permuted block size of six to receive lenalidomide (25 mg orally on days 1-21 every 28 days) until progressive disease or intolerability, or single-agent investigator's choice of either rituximab, gemcitabine, fludarabine, chlorambucil, or cytarabine. Randomisation was stratified by time from diagnosis, time from last anti-lymphoma therapy, and previous stem-cell transplantation. Individual treatment assignment between lenalidomide and investigator's choice was open label, but investigators had to register their choice of comparator drug before randomly assigning a patient. Patients who progressed on investigator's choice could cross over to lenalidomide treatment. We present the prespecified primary analysis results in the intention-to-treat population for the primary endpoint of progression-free survival, defined as the time from randomisation to progressive disease or death, whichever occurred first. Patient enrolment is complete, although treatment and collection of additional time-to-event data are ongoing. This study is registered with ClinicalTrials.gov, number NCT00875667. FINDINGS: Between April 30, 2009, and March 7, 2013, we enrolled 254 patients in the intention-to-treat population (170 [67%] were randomly assigned to receive lenalidomide, 84 [33%] to receive investigator's choice monotherapy). Patients had a median age of 68·5 years and received a median of two previous regimens. With a median follow-up of 15·9 months (IQR 7·6-31·7), lenalidomide significantly improved progression-free survival compared with investigator's choice (median 8·7 months [95% CI 5·5-12·1] vs 5·2 months [95% CI 3·7-6·9]) with a hazard ratio of 0·61 (95% CI 0·44-0·84; p=0·004). In the 167 patients in the lenalidomide group and 83 patients in the investigator's choice group who received at least one dose of treatment the most common grade 3-4 adverse events included neutropenia (73 [44%] of 167 vs 28 [34%] of 83) without increased risk of infection, thrombocytopenia (30 [18%] vs 23 [28%]), leucopenia (13 [8%] vs nine [11%]), and anaemia (14 [8%] vs six [7%]). INTERPRETATION: Patients with relapsed or refractory mantle cell lymphoma ineligible for intensive chemotherapy or stem-cell transplantation have longer progression-free survival, with a manageable safety profile when treated with lenalidomide compared with monotherapy investigator's choice options.Trněný, Marek; Lamy, Thierry; Walewski, Jan; Belada, David; Mayer, Jiri; Radford, John; Jurczak, Wojciech; Morschhauser, Franck; Alexeeva, Julia; Rule, Simon; Afanasyev, Boris; Kaplanov, Kamil; Thyss, Antoine; Kuzmin, Alexej; Voloshin, Sergey; Kuliczkowski, Kazimierz; Giza, Agnieszka; Milpied, Noel; Stelitano, Caterina; Marks, Reinhard; Trümper, Lorenz; Biyukov, Tsvetan; Patturajan, Meera; Bravo, Marie-Laure Casadebaig; Arcaini, LucaTrněný, Marek; Lamy, Thierry; Walewski, Jan; Belada, David; Mayer, Jiri; Radford, John; Jurczak, Wojciech; Morschhauser, Franck; Alexeeva, Julia; Rule, Simon; Afanasyev, Boris; Kaplanov, Kamil; Thyss, Antoine; Kuzmin, Alexej; Voloshin, Sergey; Kuliczkowski, Kazimierz; Giza, Agnieszka; Milpied, Noel; Stelitano, Caterina; Marks, Reinhard; Trümper, Lorenz; Biyukov, Tsvetan; Patturajan, Meera; Bravo, Marie Laure Casadebaig; Arcaini, Luc

Response to upfront azacitidine in juvenile myelomonocytic leukemia in the AZA-JMML-001 trial

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for most children with juvenile myelomonocytic leukemia (JMML). Novel therapies controlling the disorder prior to HSCT are needed. We conducted a phase 2, multicenter, open-label study to evaluate the safety and antileukemic activity of azacitidine monotherapy prior to HSCT in newly diagnosed JMML patients. Eighteen patients enrolled from September 2015 to November 2017 were treated with azacitidine (75 mg/m2) administered IV once daily on days 1 to 7 of a 28-day cycle. The primary end point was the number of patients with clinical complete remission (cCR) or clinical partial remission (cPR) after 3 cycles of therapy. Pharmacokinetics, genome-wide DNA-methylation levels, and variant allele frequencies of leukemia-specific index mutations were also analyzed. Sixteen patients completed 3 cycles and 5 patients completed 6 cycles. After 3 cycles, 11 patients (61%) were in cPR and 7 (39%) had progressive disease. Six of 16 patients (38%) who needed platelet transfusions were transfusion-free after 3 cycles. All 7 patients with intermediate- or low-methylation signatures in genome-wide DNA-methylation studies achieved cPR. Seventeen patients received HSCT; 14 (82%) were leukemia-free at a median follow-up of 23.8 months (range, 7.0-39.3 months) after HSCT. Azacitidine was well tolerated and plasma concentration-–time profiles were similar to observed profiles in adults. In conclusion, azacitidine monotherapy is a suitable option for children with newly diagnosed JMML. Although long-term safety and efficacy remain to be fully elucidated in this population, these data demonstrate that azacitidine provides valuable clinical benefit to JMML patients prior to HSCT. This trial was registered at www.clinicaltrials.gov as #NCT02447666