The Effect of Genetic Background and Dose on Non-Targeted Effects of Radiation

Purpose: This work investigates the hypothesis that genetic background plays a significant role in the signalling mechanisms underlying induction and perpetuation of genomic instability following radiation exposure. Materials and methods: Bone marrow from two strains of mice (CBA and C57) were exposed to a range of X-ray doses (0, 0.01, 0.1, 1 and 3 Gy). Different cellular signalling endpoints: Apoptosis, cytokine levels and calcium flux, were evaluated at 2 h, 24 h and 7 d post-irradiation to assess immediate and delayed effects. Results: In CBA (radiosensitive) elevated apoptosis levels were observed at 24 h post X-irradiation, and transforming growth factor-β (TGF-β) levels which increased with time and dose. C57 showed a higher background level of apoptosis, and sustained apoptotic levels 7 days after radiation exposure. Levels of tumor necrosis factor-α (TNF-α were increased in C57 at day 7 for higher X-ray doses. TGF-β levels were higher in CBA, whilst C57 exhibited a greater TNF-α response. Calcium flux was induced in reporter cells on exposure to conditioned media from both strains. Conclusions: These results show genetic and dose specific differences in radiation-induced signalling in the initiation and perpetuation of the instability process, which have potential implications on evaluation of non-targeted effects in radiation risk assessment

KMT2A associates with PHF5A-PHF14-HMG20A-RAI1 subcomplex in pancreatic cancer stem cells and epigenetically regulates their characteristics

Pancreatic cancer (PC), one of the most aggressive and life-threatening human malignancies, is known for its resistance to cytotoxic therapies. This is increasingly ascribed to the subpopulation of undifferentiated cells, known as pancreatic cancer stem cells (PCSCs), which display greater evolutionary fitness than other tumor cells to evade the cytotoxic effects of chemotherapy. PCSCs are crucial for tumor relapse as they possess ‘stem cell-like’ features that are characterized by self-renewal and differentiation. However, the molecular mechanisms that maintain the unique characteristics of PCSCs are poorly understood. Here, we identify the histone methyltransferase KMT2A as a physical binding partner of an RNA polymerase-associated PHF5A-PHF14-HMG20A-RAI1 protein subcomplex and an epigenetic regulator of PCSC properties and functions. Targeting the protein subcomplex in PCSCs with a KMT2A-WDR5 inhibitor attenuates their self-renewal capacity, cell viability, and in vivo tumorigenicity

BRD9-SMAD2/3 orchestrates stemness and tumorigenesis in pancreatic ductal adenocarcinoma

Background and Aims The dismal prognosis of pancreatic ductal adenocarcinoma (PDAC) is linked to the presence of pancreatic cancer stem-like cells (CSCs) that respond poorly to current chemotherapy regimens. The epigenetic mechanisms regulating CSCs are currently insufficiently understood, which hampers the development of novel strategies for eliminating CSCs. Methods By small molecule compound screening targeting 142 epigenetic enzymes, we identified that bromodomain-containing protein BRD9, a component of the BAF histone remodeling complex, is a key chromatin regulator to orchestrate the stemness of pancreatic CSCs via cooperating with the TGFβ/Activin-SMAD2/3 signaling pathway. Results Inhibition and genetic ablation of BRD9 block the self-renewal, cell cycle entry into G0 phase and invasiveness of CSCs, and improve the sensitivity of CSCs to gemcitabine treatment. In addition, pharmacological inhibition of BRD9 significantly reduced the tumorigenesis in patient-derived xenografts mouse models and eliminated CSCs in tumors from pancreatic cancer patients. Mechanistically, inhibition of BRD9 disrupts enhancer-promoter looping and transcription of stemness genes in CSCs. Conclusions Collectively, the data suggest BRD9 as a novel therapeutic target for PDAC treatment via modulation of CSC stemness

RBL2-E2F-GCN5 guide cell fate decisions during tissue specification by regulating cell-cycle-dependent fluctuations of non-cell-autonomous signaling

Summary: The retinoblastoma family proteins (RBs) and E2F transcription factors are cell-autonomous regulators of cell-cycle progression, but they also impact fate choice in addition to tumor suppression. The range of mechanisms involved remains to be uncovered. Here, we show that RBs, particularly RBL2/p130, repress WNT ligands such as WNT4 and WNT8A, thereby directing ectoderm specification between neural crest to neuroepithelium. RBL2 achieves this function through cell-cycle-dependent cooperation with E2Fs and GCN5 on the regulatory regions of WNT loci, which direct neuroepithelial versus neural crest specification by temporal fluctuations of WNT/β-catenin and DLL/NOTCH signaling activity. Thus, the RB-E2F bona fide cell-autonomous axis controls cell fate decisions, and RBL2 regulates field effects via WNT ligands. This reveals a non-cell-autonomous function of RBL2-E2F in stem cell and tissue progenitor differentiation that has broader implications for cell-cycle-dependent cell fate specification in organogenesis, adult stem cells, tissue homeostasis, and tumorigenesis

Effects of Composite Attachments on Orthodontic Clear Aligners Therapy: A Systematic Review

This systematic review aims to highlight the differences between different clear aligner therapies that differ in the presence of attachments or in attachment configuration. Eight electronic databases were searched up to March 2020. Two authors independently proceeded to study selection, data extraction, and risk of bias assessment. The analysis of the results was carried out examining six groups of movements (mesio-distal tipping/bodily movement; anterior bucco-lingual tipping/root torque; posterior bucco-lingual tipping/expansion; intrusion; extrusion; rotation). Five clinical trials were selected and all of them showed a medium risk of bias. Literature showed that attachments mostly increase the effectiveness of orthodontic treatment with clear aligners, improving anterior root torque, rotation, and mesio-distal (M-D) movement; they are also important to increase posterior anchorage. However, some articles showed contradictory or not statistically significant results. Attachments also seem to improve intrusion, but the evidence about this movement, as well as extrusion, is lacking. No studies evaluated posterior bucco-lingual tipping/expansion. Further clinical trials are strongly suggested to clarify the influence of attachments and their number, size, shape, and position on each orthodontic movement

KMT2A associates with PHF5A-PHF14-HMG20A-RAI1 subcomplex in pancreatic cancer stem cells and epigenetically regulates their characteristics.

Pancreatic cancer (PC), one of the most aggressive and life-threatening human malignancies, is known for its resistance to cytotoxic therapies. This is increasingly ascribed to the subpopulation of undifferentiated cells, known as pancreatic cancer stem cells (PCSCs), which display greater evolutionary fitness than other tumor cells to evade the cytotoxic effects of chemotherapy. PCSCs are crucial for tumor relapse as they possess stem cell-like features that are characterized by self-renewal and differentiation. However, the molecular mechanisms that maintain the unique characteristics of PCSCs are poorly understood. Here, we identify the histone methyltransferase KMT2A as a physical binding partner of an RNA polymerase-associated PHF5A-PHF14-HMG20A-RAI1 protein subcomplex and an epigenetic regulator of PCSC properties and functions. Targeting the protein subcomplex in PCSCs with a KMT2A-WDR5 inhibitor attenuates their self-renewal capacity, cell viability, and in vivo tumorigenicity

KMT2A associates with PHF5A-PHF14-HMG20A-RAI1 subcomplex in pancreatic cancer stem cells and epigenetically regulates their characteristics

Abstract Pancreatic cancer (PC), one of the most aggressive and life-threatening human malignancies, is known for its resistance to cytotoxic therapies. This is increasingly ascribed to the subpopulation of undifferentiated cells, known as pancreatic cancer stem cells (PCSCs), which display greater evolutionary fitness than other tumor cells to evade the cytotoxic effects of chemotherapy. PCSCs are crucial for tumor relapse as they possess ‘stem cell-like’ features that are characterized by self-renewal and differentiation. However, the molecular mechanisms that maintain the unique characteristics of PCSCs are poorly understood. Here, we identify the histone methyltransferase KMT2A as a physical binding partner of an RNA polymerase-associated PHF5A-PHF14-HMG20A-RAI1 protein subcomplex and an epigenetic regulator of PCSC properties and functions. Targeting the protein subcomplex in PCSCs with a KMT2A-WDR5 inhibitor attenuates their self-renewal capacity, cell viability, and in vivo tumorigenicity

Epigenetic and transcriptional regulations prime cell fate before division during human pluripotent stem cell differentiation.

Funder: Federation of European Biochemical SocietiesStem cells undergo cellular division during their differentiation to produce daughter cells with a new cellular identity. However, the epigenetic events and molecular mechanisms occurring between consecutive cell divisions have been insufficiently studied due to technical limitations. Here, using the FUCCI reporter we developed a cell-cycle synchronised human pluripotent stem cell (hPSC) differentiation system for uncovering epigenome and transcriptome dynamics during the first two divisions leading to definitive endoderm. We observed that transcription of key differentiation markers occurs before cell division, while chromatin accessibility analyses revealed the early inhibition of alternative cell fates. We found that Activator protein-1 members controlled by p38/MAPK signalling are necessary for inducing endoderm while blocking cell fate shifting toward mesoderm, and that enhancers are rapidly established and decommissioned between different cell divisions. Our study has practical biomedical utility for producing hPSC-derived patient-specific cell types since p38/MAPK induction increased the differentiation efficiency of insulin-producing pancreatic beta-cells