HDAC6 mediates the acetylation of TRIM50

The E3 Ubiquitin ligase TRIM50 promotes the formation and clearance of aggresome-associated polyubiquitinated proteins through HDAC6 interaction, a tubulin specific deacetylase that regulates microtubule-dependent aggresome formation. In this report we showed that TRIM50 is a target of HDAC6 with Lys-372 as a critical residue for acetylation. We identified p300 and PCAF as two TRIM50 acetyltransferases and we further showed that a balance between ubiquitination and acetylation regulates TRIM50 degradatio

The psychological impact of COVID-19 pandemic on patients with neuroendocrine tumors: Between resilience and vulnerability

The COVID-19 pandemic has added another layer of complexity to the fears of patients with neuroendocrine tumors (NETs). Little is known regarding the psychological impact of the COVID-19 outbreak on patients with gastroenteropancreatic or bronchopulmonary (BP) NETs. We longitudinally surveyed the mental symptoms and concerns of NET patients during the plateau phase of the first (W1) and second epidemic waves (W2) in Italy. Seven specific constructs (depression, anxiety, stress, health-related quality of life, NET-related quality of life, patient–physician relationship, psychological distress) were investigated using validated screening instruments, including DASS-21, EORTC QLQ-C30, EORTC QLQ GI.NET21, PDRQ9 and IES-R. We enrolled 197 patients (98 males) with a median age of 62 years. The majority of the patients had G1/G2 neoplasms. Some 38% of the patients were on active treatment. At W1, the prevalence of depression, anxiety and stress was 32%, 36% and 26% respectively. The frequency of depression and anxiety increased to 38% and 41% at W2, whereas no modifications were recorded in the frequency of stress. Poor educational status was associated with higher levels of anxiety at both W1 (odds ratio [OR] = 1.33 ± 0.22; p =.07) and W2 (OR = 1.45 ± 0.26; p =.03). Notably, post-traumatic stress symptoms were observed in the 58% of the patients, and both single marital status (OR = 0.16, 95% confidence interval [CI] = 0.06–0.48; p =.0009) and low levels of formal education (OR = 0.47, 95% CI = 0.23–0.99; p =.05) predicted their occurrence. No significant deteriorations of health-related quality of life domains were observed from W1 to W2. High patient care satisfaction was documented despite the changes in health systems resource allocation. NET patients have an increased risk of developing post-traumatic stress symptoms as result of the COVID-19 pandemic. Specific screening measures and psychological interventions should be implemented in NET clinics to prevent, recognize and treat mental distress in this vulnerable population

DAXX mutations as potential genomic markers of malignant evolution in small nonfunctioning pancreatic neuroendocrine tumors

Management of localized well-differentiated pancreatic neuroendocrine tumors (panNETs) is controversial and primarily dependent on tumor size. Upfront surgery is usually recommended for tumors larger than 2 cm in diameter since they frequently show metastatic potential, whereas smaller panNETs are generally characterized by an indolent clinical course, with a rate of relapse or metastasis below 15%. To explore whether increased tumor size is paralleled by genomic variations, we compared the rate and the mutational patterns of putative driver genes that are recurrently altered in these tumors by investigating differential cohorts of panNET surgical specimens smaller (n = 27) or larger than 2 cm (n = 29). We found that the cumulative number of mutations detected in panNETs >2 cm was significantly higher (p = 0.03) relative to smaller tumors, while mutations of DAXX were significantly more frequent in the cohort of larger tumors (p = 0.05). Moreover, mutations of DAXX were associated with features of malignancy including increased grade, nodal involvement and lymphovascular invasion, and independently predicted both relapse after surgery (p = 0.05) and reduced DFS in multivariable analysis (p = 0.02). Our data suggest that alterations of the DAXX/ATRX molecular machinery increase the malignant potential of panNETs, and that identification of mutations of DAXX/ATRX in small, nonfunctioning tumors can predict the malignant progression observed in a minority of them

TRIM50 regulates Beclin 1 proautophagic activity

Autophagy is a catabolic process needed for maintaining cell viability and homeostasis in response to numerous stress conditions. Emerging evidence indicates that the ubiquitin system has a major role in this process. TRIMs, an E3 ligase protein family, contribute to selective autophagy acting as receptors and regulators of the autophagy proteins recognizing endogenous or exogenous targets through intermediary autophagic tags, such as ubiquitin. Here we report that TRIM50 fosters the initiation phase of starvation-induced autophagy and associates with Beclin1, a central component of autophagy initiation complex. We show that TRIM50, via the RING domain, ubiquitinates Beclin 1 in a K63-dependent manner enhancing its binding with ULK1 and autophagy activity. Finally, we found that the Lys-372 residue of TRIM50, critical for its own acetylation, is necessary for its E3 ligase activity that governs Beclin1 ubiquitination. Our study expands the roles of TRIMs in regulating selective autophagy, revealing an acetylation-ubiquitination dependent control for autophagy modulation. © 2018 Elsevier B.V

Reversal of <i>MYB </i>-dependent suppression of <i>MAFB </i>expression overrides leukaemia phenotype in MLL-rearranged AML

Abstract The transcription factor MYB plays a pivotal role in haematopoietic homoeostasis and its aberrant expression is involved in the genesis and maintenance of acute myeloid leukaemia (AML). We have previously demonstrated that not all AML subtypes display the same dependency on MYB expression and that such variability is dictated by the nature of the driver mutation. However, whether this difference in MYB dependency is a general trend in AML remains to be further elucidated. Here, we investigate the role of MYB in human leukaemia by performing siRNA-mediated knock-down in cell line models of AML with different driver lesions. We show that the characteristic reduction in proliferation and the concomitant induction of myeloid differentiation that is observed in MLL-rearranged and t(8;21) leukaemias upon MYB suppression is not seen in AML cells with a complex karyotype. Transcriptome analyses revealed that MYB ablation produces consensual increase of MAFB expression in MYB-dependent cells and, interestingly, the ectopic expression of MAFB could phenocopy the effect of MYB suppression. Accordingly, in silico stratification analyses of molecular data from AML patients revealed a reciprocal relationship between MYB and MAFB expression, highlighting a novel biological interconnection between these two factors in AML and supporting new rationales of MAFB targeting in MLL-rearranged leukaemias

Adoptive T-cell immunotherapy in digestive tract malignancies: Current challenges and future perspectives

Multiple systemic treatments are currently available for advanced cancers of the digestive tract, but none of them is curative. Adoptive T-cell immunotherapy refers to the extraction, modification and re-infusion of autologous or allogenic T lymphocytes for therapeutic purposes. A number of clinical trials have investigated either non-engineered T cells (i.e., lymphokine-activated killer cells, cytokine induced killer cells, or tumor-infiltrating lymphocytes) or engineered T cells (T cell receptor-redirected T cells or chimeric antigen receptor T cells) in patients with digestive tract malignancies over the past two decades, with variable degrees of success. While the majority of completed trials have been primarily aimed at assessing the safety of T-cell transfer strategies, a new generation of studies is being designed to formally evaluate the antitumor potential of adoptive T-cell immunotherapy in both the metastatic and adjuvant settings. In this review, we provide an overview of completed and ongoing clinical trials of passive T-cell immunotherapy in patients with cancers of the digestive tract, focusing on present obstacles and future strategies for achieving potential success

Cutting edge: The NLRP3 inflammasome links complement-mediated inflammation and IL-1β release

The complement system is a potent component of the innate immune response, promoting inflammation and orchestrating defense against pathogens. However, dysregulation of complement is critical to several autoimmune and inflammatory syndromes. Elevated expression of the proinflammatory cytokine IL-1β is often linked to such diseases. In this study, we reveal the mechanistic link between complement and IL-1β secretion using murine dendritic cells. IL-1β secretion occurs following intracellular caspase-1 activation by inflammasomes. We show that complement elicits secretion of both IL-1β and IL-18 in vitro and in vivo via the NLRP3 inflammasome. This effect depends on the inflammasome components NLRP3 and ASC, as well as caspase-1 activity. Interestingly, sublethal complement membrane attack complex formation, but not the anaphylatoxins C3a and C5a, activated the NLRP3 inflammasome in vivo. These findings provide insight into the molecular processes underlying complement-mediated inflammation and highlight the possibility of targeting IL-1β to control complement-induced disease and pathological inflammation

Dissecting KMT2D missense mutations in Kabuki syndrome patients

Kabuki syndrome is a rare autosomal dominant condition characterized by facial features, various organs malformations, postnatal growth deficiency and intellectual disability. The discovery of frequent germline mutations in the histone methyltransferase KMT2D and the demethylase KDM6A revealed a causative role for histone modifiers in this disease. However, the role of missense mutations has remained unexplored. Here, we expanded the mutation spectrum of KMT2D and KDM6A in KS by identifying 37 new KMT2D sequence variants. Moreover, we functionally dissected 14 KMT2D missense variants, by investigating their impact on the protein enzymatic activity and the binding to members of the WRAD complex. We demonstrate impaired H3K4 methyltransferase activity in 9 of the 14 mutant alleles and show that this reduced activity is due in part to disruption of protein complex formation. These findings have relevant implications for diagnostic and counseling purposes in this disease