Clinical relevance of the transcriptional signature regulated by CDC42 in colorectal cancer

CDC42 is an oncogenic Rho GTPase overexpressed in colorectal cancer (CRC). Although CDC42 has been shown to regulate gene transcription, the specific molecular mechanisms regulating the oncogenic ability of CDC42 remain unknown. Here, we have characterized the transcriptional networks governed by CDC42 in the CRC SW620 cell line using gene expression analysis. Our results establish that several cancer-related signaling pathways, including cell migration and cell proliferation, are regulated by CDC42. This transcriptional signature was validated in two large cohorts of CRC patients and its clinical relevance was also studied. We demonstrate that three CDC42-regulated genes offered a better prognostic value when combined with CDC42 compared to CDC42 alone. In particular, the concordant overexpression of CDC42 and silencing of the putative tumor suppressor gene CACNA2D2 dramatically improved the prognostic value. The CACNA2D2/CDC42 prognostic classifier was further validated in a third CRC cohort as well as in vitro and in vivo CRC models. Altogether, we show that CDC42 has an active oncogenic role in CRC via the transcriptional regulation of multiple cancer-related pathways and that CDC42-mediated silencing of CACNA2D2 is clinically relevant. Our results further support the use of CDC42 specific inhibitors for the treatment of the most aggressive types of CRCThis work has been supported by grants to JCL from Ministerio de Ciencia e Innovación (SAF2008- 03750, RD06-0020-0016 and RD12/0036/0019) and to DGO Cancer Institute New South Wales (2017/CDF625). FVM is a National Breast Cancer Foundation/Cure Cancer Australia Foundation Postdoctoral Training Fellow

A Read/Write Mechanism Connects p300 Bromodomain Function to H2A.Z Acetylation

Acetylation of the histone variant H2A.Z (H2A.Zac) occurs at active regulatory regions associated with gene expression. Although the Tip60 complex is proposed to acetylate H2A.Z, functional studies suggest additional enzymes are involved. Here, we show that p300 acetylates H2A.Z at multiple lysines. In contrast, we found that although Tip60 does not efficiently acetylate H2A.Z in vitro, genetic inhibition of Tip60 reduces H2A.Zac in cells. Importantly, we found that interaction between the p300-bromodomain and H4 acetylation (H4ac) enhances p300-driven H2A.Zac. Indeed, H2A.Zac and H4ac show high genomic overlap, especially at active promoters. We also reveal unique chromatin features and transcriptional states at enhancers correlating with co-occurrence or exclusivity of H4ac and H2A.Zac. We propose that differential H4 and H2A.Z acetylation signatures can also define the enhancer state. In conclusion, we show both Tip60 and p300 contribute to H2A.Zac and reveal molecular mechanisms of writer/reader crosstalk between H2A.Z and H4 acetylation through p300

Single-cell transcriptomics reveals involution mimicry during the specification of the basal breast cancer subtype

Basal breast cancer is associated with younger age, early relapse, and a high mortality rate. Here, we use unbiased droplet-based single-cell RNA sequencing (RNA-seq) to elucidate the cellular basis of tumor progression during the specification of the basal breast cancer subtype from the luminal progenitor population in the MMTV-PyMT (mouse mammary tumor virus-polyoma middle tumor-antigen) mammary tumor model. We find that basal-like cancer cells resemble the alveolar lineage that is specified upon pregnancy and encompass the acquisition of an aberrant post-lactation developmental program of involution that triggers remodeling of the tumor microenvironment and metastatic dissemination. This involution mimicry is characterized by a highly interactive multicellular network, with involution cancer-associated fibroblasts playing a pivotal role in extracellular matrix remodeling and immunosuppression. Our results may partially explain the increased risk and poor prognosis of breast cancer associated with childbirth.</p

Dissecting the role of histone variant H2A.Z acetylation in transcription regulation

Acetylation of the human histone variant H2A.Z occurs at promoter regions and is associated with gene expression, however, the role of H2A.Zac at other regulatory regions, including enhancers is still poorly understood. Moreover, any functional studies beyond correlative studies, in particular concerning a direct role for H2A.Z acetylation in gene transcription, are lacking. My studies presented as part of my PhD thesis have addressed the gap of knowledge in many of these important questions regarding the role of H2A.Zac in regulation of gene expression.First, I show that H2A.Zac-containing nucleosomes are also found at enhancers of LNCaP and VCaP human prostate cell lines and that a re-distribution of H2A.Zac occurs to form cancer-related enhancers. Notably, H2A.Zac plays an important role in activation of androgen receptor (AR)-enhancers. H2A.Zac nucleosomes mark AR binding sites and upon androgen induction these nucleosomes are rapidly remodelled to form nucleosome-free regions allowing expression of AR-enhancer RNAs. Next, I identify the histone acetyltransferases responsible for H2A.Zac in humans and a novel molecular mechanism of writer/reader crosstalk between H2A.Z and H4 acetylation. I show p300 acetylates H2A.Z at multiple lysines both in vitro and in cells. Importantly, I found that the interaction between the bromodomain of p300 and H4 acetylation enhances p300-driven H2A.Z acetylation. Finally, I examine the causal role of H2A.Zac in transcription, at both promoters and enhancers. For this, I generated inducible models in LNCaP cells where I overexpress a non-acetylable H2A.Z mutant or a constant acetylated form. RNAseq analysis reveals that reduced H2A.Zac levels result in a genome-wide increase in intron retention, although global gene expression was not altered. Cells lacking H2A.Zac also show accumulation of paused RNA polymerase II (RNAPII) at both promoters and enhancers, and a decrease of eRNA expression at enhancers. My data suggests that H2A.Zac regulates RNAPII kinetics and subsequently both splicing and enhancer function. Altogether, in my thesis I have discovered novel mechanisms for H2A.Zac transcriptional regulation, from identification of the H2A.Zac acetyltransferase (writer) to the downstream consequences of H2A.Zac nucleosome occupancy at promoters and enhancer elements

Cyclosporin promotes neurorestoration and cell replacement therapy in pre-clinical models of Parkinson's disease.

The early clinical trials using fetal ventral mesencephalic (VM) allografts in Parkinson's disease (PD) patients have shown efficacy (albeit not in all cases) and have paved the way for further development of cell replacement therapy strategies in PD. The preclinical work that led to these clinical trials used allografts of fetal VM tissue placed into 6-OHDA lesioned rats, while the patients received similar allografts under cover of immunosuppression in an α-synuclein disease state. Thus developing models that more faithfully replicate the clinical scenario would be a useful tool for the translation of such cell-based therapies to the clinic

El defensor : Diario Liberal independiente, protector de los intereses materiales y morales de esta provincia: Año II Epoca 2ª Número 217 - 1904 noviembre 4

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

DNA Hypermethylation Encroachment at CpG Island Borders in Cancer Is Predisposed by H3K4 Monomethylation Patterns

Promoter CpG islands are typically unmethylated in normal cells, but in cancer a proportion are subject to hypermethylation. Using methylome sequencing we identified CpG islands that display partial methylation encroachment across the 5′ or 3′ CpG island borders. CpG island methylation encroachment is widespread in prostate and breast cancer and commonly associates with gene suppression. We show that the pattern of H3K4me1 at CpG island borders in normal cells predicts the different modes of cancer CpG island hypermethylation. Notably, genetic manipulation of Kmt2d results in concordant alterations in H3K4me1 levels and CpG island border DNA methylation encroachment. Our findings suggest a role for H3K4me1 in the demarcation of CpG island methylation borders in normal cells, which become eroded in cancer.We thank the Wysocka Laboratory for the generous gift of wild-type and mutant mESCs (Dorighi et al., 2017) and Roger Daly for financial support of prostate cancer WGBS (Cancer Institute NSW, Australia, program grant).The Bill and Patricia Ritchie Foundation, Australia (C.C.G.); UNSW Sydney University International Postgraduate Award (UIPA), Australia (K.S.

DNA Hypermethylation Encroachment at CpG Island Borders in Cancer Is Predisposed by H3K4 Monomethylation Patterns.

Promoter CpG islands are typically unmethylated in normal cells, but in cancer a proportion are subject to hypermethylation. Using methylome sequencing we identified CpG islands that display partial methylation encroachment across the 5' or 3' CpG island borders. CpG island methylation encroachment is widespread in prostate and breast cancer and commonly associates with gene suppression. We show that the pattern of H3K4me1 at CpG island borders in normal cells predicts the different modes of cancer CpG island hypermethylation. Notably, genetic manipulation of Kmt2d results in concordant alterations in H3K4me1 levels and CpG island border DNA methylation encroachment. Our findings suggest a role for H3K4me1 in the demarcation of CpG island methylation borders in normal cells, which become eroded in cancer

EXTH-36. COMBINING ONC201 AND PAXALISIB FOR THE TREATMENT OF DIFFUSE MIDLINE GLIOMA (DMG); THE PRECLINICAL RESULTS UNDERPINNING THE INTERNATIONAL PHASE II CLINICAL TRIAL (NCT05009992)

Diffuse midline gliomas (DMGs) diagnosed in the pons (DIPG) are universally fatal central nervous system tumors and are the leading cause of cancer-related death in children. Palliative radiotherapy is the only recognized treatment, with median overall survival just 9-11 months. The brain-penetrant, small molecule, ONC201, shows early-stage clinical trial efficacy, extending survival by ~9-11 months compared to historic controls. However, studies to determine the mechanisms behind the temporary clinical response to ONC201 are needed. Here, we have used a systems-biological approach to investigate whether genomic features influenced ONC201 response. DMGs harboring PIK3CA mutations were more sensitive to ONC201, whereas those harboring TP53 mutations were less sensitive. Quantitative proteogenomics identified that ONC201 elicits potent agonism of the mitochondrial protease, ClpP, driving proteolysis of electron transport chain and tricarboxylic acid proteins, leading to mitochondrial dysfunction. However, metabolic adaptation to ONC201 is promoted by the spare redox-signaling capacity of cells harboring WT-PIK3CA that was counteracted using the brain-penetrant PI3K/Akt/mTOR inhibitor, paxalisib. ONC201 and paxalisib combinations extended survival of orthotopic DIPG xenograft mouse models (SU-DIPG-VI, p=0.0027; SF8626, p=0.0002; HSJD-DIPG-007, p=&amp;lt; 0.0001). The combination in the first three recorded patients; two at progression following re-irradiation, and one at diagnosis following the completion of radiation, resulted in dramatic reductions in tumor area, dramatically extending overall survival for all three patients (25 months, 30 and 31 months continuing). The DIPG patient receiving the combination since diagnosis, remains in progression free survival (MR axial diagnosis scan = 1554 mm2, current tumour area = 306 mm2, ~80% reduction). The patient continuing to receive the combination at progression and following reirradiation also experienced a marked decrease in tumor size (MR axial diagnosis scan = 1248 mm2, current tumour area = 315 mm2, ~75% reduction), 10 months following radiological detection of progression. These data inform the phase II clinical trial (NCT05009992)