NF-Y subunits overexpression in gastric adenocarcinomas (STAD)

NF-Y is a pioneer transcription factor—TF—formed by the Histone-like NF-YB/NF-YC subunits and the regulatory NF-YA. It binds to the CCAAT box, an element enriched in promoters of genes overexpressed in many types of cancer. NF-YA is present in two major isoforms—NF-YAs and NF-YAl—due to alternative splicing, overexpressed in epithelial tumors. Here we analyzed NF-Y expression in stomach adenocarcinomas (STAD). We completed the partitioning of all TCGA tumor samples (450) according to molecular subtypes proposed by TCGA and ACRG, using the deep learning tool DeepCC. We analyzed differentially expressed genes—DEG—for enriched pathways and TFs binding sites in promoters. CCAAT is the predominant element only in the core group of genes upregulated in all subtypes, with cell-cycle gene signatures. NF-Y subunits are overexpressed, particularly NF-YA. NF-YAs is predominant in CIN, MSI and EBV TCGA subtypes, NF-YAl is higher in GS and in the ACRG EMT subtypes. Moreover, NF-YAlhigh tumors correlate with a discrete Claudinlow cohort. Elevated NF-YB levels are protective in MSS;TP53+ patients, whereas high NF-YAl/NF-YAs ratios correlate with worse prognosis. We conclude that NF-Y isoforms are associated to clinically relevant features of gastric cancer.

Preclinical Development of EDIT301, an Autologous Cell Therapy Comprising AsCas12a-RNP Modified Mobilized Peripheral Blood-CD34 + Cells for the Potential Treatment of Transfusion Dependent Beta Thalassemia

Beta thalassemia is one of the most common recessive hematological disorders in the world with more than 200 mutations identified to date. These mutations reduce or completely abrogate beta globin expression. As beta globin pairs with alpha globin to form adult hemoglobin (HbA, α2β2), reduced or absent beta globin results in excessive alpha globin chains, which form toxic aggregates. These aggregates cause maturation blockade and premature death of erythroid precursors, and hemolysis of red blood cells (RBC), leading to varying degrees of anemia. Patients with the most severe form of beta thalassemia, namely beta thalassemia major, are transfusion-dependent, i.e., requiring life-long RBC transfusions accompanied by the burden of iron chelation therapy. EDIT-301 is an experimental autologous cell therapy in which CD34 + cells are genetically modified to promote gamma globin expression. EDIT-301 is currently in clinical development for sickle cell disease, and IND enabling stage for transfusion-dependent beta thalassemia (TDT). Gamma globin decreases the alpha to beta globin chain imbalance in beta thalassemia by pairing with the over-abundant alpha globin chains to form fetal hemoglobin (HbF, α2γ2). Gamma globin induction, and consequently HbF induction, for EDIT-301 is achieved through AsCas12a ribonucleoprotein (RNP)-mediated editing of the distal CCAAT box region of the HBG1 and HBG2 promoters, where naturally occurring hereditary persistence of fetal hemoglobin (HFPH) mutations exist. We chose this target over BCL11A based on previous preclinical data demonstrating that BCL11A editing reduces erythroid output in NBSGW mice. An engineered AsCas12a RNP edits the HBG1 and HBG2 promoter distal CCAAT box with high efficiency and specificity. We have previously shown that on-target editing of >80% was achieved in mobilized peripheral blood (mPB) CD34 + cells from normal donors with no detectable off-target editing both at research scale and at clinical manufacturing scale. Edited normal donor CD34 + cells led to long-term, polyclonal, multilineage engraftment without lineage skewing in immunocompromised mice and sustained robust HbF production in their erythroid progeny. To test whether EDIT-301 may be an efficacious therapy for TDT, mPB CD34 + cells from individuals with TDT were electroporated with the engineered AsCas12a RNP targeting the HBG1 and HBG2 promoters. AsCas12a RNP edited mPB CD34 + cells from individuals with TDT as efficiently as CD34 + cells from normal donors. Importantly, EDIT-301 has the potential to address the underlying pathophysiology of TDT, i.e., the maturation blockade and premature death of erythroid precursors. Erythroid differentiation of edited beta thalassemia CD34 + cells showed significant improvement in erythroid maturation and health. Specifically, ~70% edited erythroblasts reached late erythroblast stage compared to ~53% unedited erythroblasts; ~56% edited erythroid cells underwent terminal maturation and enucleated compared to ~28% of unedited erythroid cells; and non-viable erythroblasts decreased from ~33% to ~22% after editing. The improved erythropoiesis was accompanied by significantly increased total hemoglobin content per cell. These data strongly support that editing of the HBG1 and HBG2 promoter CCAAT box using engineered AsCas12a RNP can reverse the dyserythropoiesis associated with beta thalassemia and increase the hemoglobin production. In summary, we have provided strong preclinical data supporting the development of EDIT-301 for the treatment of TDT. Edited mPB CD34 + cells retained their ability to engraft without lineage skewing, resulted in robust HbF induction long-term, improved erythropoiesis, and increased hemoglobin content in TDT erythroid cells. These data support that a single administration of EDIT-301 may have the potential to safely and effectively reverse dyserythropoiesis and ameliorate anemia in individuals with TDT long-term. Clinical studies to demonstrate the safety and efficacy of EDIT-301 in the treatment of TDT are currently being planned. Disclosures Sousa: Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Janoudi: Editas Medicine: Current Employment, Current equity holder in publicly-traded company. deDreuzy: Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Shearman: Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Zhang: Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Chang: Editas Medicine: Current Employment, Current equity holder in publicly-traded company.

Cooperative DNA base and shape recognition by the CCAAT-binding complex and its bZIP transcription factor HapX

The heterotrimeric CCAAT-binding complex (CBC) is a master regulator of transcription. It specifically recognizes the CCAAT-box, a fundamental eukaryotic promoter element. Certain fungi, like Aspergilli, encode a fourth CBC-subunit, HapX, to fine-tune expression of genes involved in iron metabolism. Although being a basic region leucine zipper with its own DNA recognition motif, HapX function strictly relies on the CBC. We here report two crystal structures of the CBC-HapX complex bound to DNA duplexes with distinct sequence and position of HapX sites. In either structure, a HapX dimer targets the nucleic acid downstream of the CCAAT-box and the leash like N-terminus of the distal HapX subunit interacts with CBC and DNA. In vitro and in vivo analyses of HapX mutants support the structures, highlight the complex as an exceptional major and minor groove DNA binder, and enrich our understanding of the functional as well as structural plasticity of related complexes across species.

NF-Y Subunits Overexpression in HNSCC

NF-Y is the CCAAT-binding trimer formed by the histone fold domain (HFD), NF-YB/NF-YC and NF-YA. The CCAAT box is generally prevalent in promoters of “cancer” genes. We reported the overexpression of NF-YA in BRCA, LUAD and LUSC, and of all subunits in HCC. Altered splicing of NF-YA was found in breast and lung cancer. We analyzed RNA-seq datasets of TCGA and cell lines of head and neck squamous cell carcinomas (HNSCC). We partitioned all TCGA data into four subtypes, deconvoluted single-cell RNA-seq of tumors and derived survival curves. The CCAAT box was enriched in the promoters of overexpressed genes. The “short” NF-YAs was overexpressed in all subtypes and the “long” NF-YAl in Mesenchymal. The HFD subunits are overexpressed, except Basal (NF-YB) and Atypical (NF-YC); NF-YAl is increased in p53 mutated tumors. In HPV-positive tumors, high levels of NF-YAs, p16 and ΔNp63 correlate with better prognosis. Deconvolution of single cell RNA-seq (scRNA-seq) found a correlation of NF-YAl with Cancer Associated Fibroblasts (CAFs) and p-EMT cells, a population endowed with metastatic potential. We conclude that overexpression of HFD subunits and NF-YAs is protective in HPV-positive tumors; expression of NF-YAl is largely confined to mutp53 tumors and malignant p-EMT cells.

IL PUNTO DI VISTA DI UN REGOLATORE EPIGENETICO DELL’ESPRESSIONE GENICA, COMUNE A UOMO E PIANTE

The regulation of gene expression is at the heart of all the fundamental processes of living organisms. It is controlled by Transcriptional Factors which, by binding to specific DNA sequences of genomes, recruit protein machineries that modify the organization of chromatin (epigenetics). Our studies are focused on the NF-Y trimeric transcription factor, a crucial activator of gene expression in all eukaryotes. Two subunits have a structure similar to histones, the basic elements of chromatin, the third -NF-YA- confers specificity to the CCAAT box. I will illustrate how regulation of NF-Y complexes is important for two completely different gene expression systems: the neoplastic transformation of human cells, and the development of flowers in plants.

MBRS-42. YB-1 - A NOVEL THERAPEUTIC TARGET IN HIGH-RISK MEDULLOBLASTOMA?

Medulloblastoma relapse occurs in 30–40% of patients and is typically fatal. The emergence of therapy resistant sub-clones likely plays a major role in a large proportion of recurrent medulloblastoma. Y-box binding protein 1 (YB-1) is a multifunctional transcription/translation factor and known onco-protein. Overexpression has been described in numerous cancers, where elevated expression and nuclear accumulation correlates with disease progression, metastasis and drug resistance. Genomic analysis of a large medulloblastoma cohort revealed YB-1 up-regulation across all subgroups of medulloblastoma, where elevated expression correlated with poor survival. Immunohistochemical staining of patient tissue microarrays displayed significant YB-1 expression, with a high proportion (83%) of patients exhibiting nuclear accumulation. High YB-1 expression was also observed at both protein and RNA level across medulloblastoma cell lines, with expression highest in Group 3 and 4. Hence, we hypothesised that YB-1 plays a role in medulloblastoma chemoresistance and progression. Treatment of Group 3 (HDMB-03 and D283MED) and SHH (DAOY) cell lines with vincristine and cisplatin and analysis of cellular localisation by nuclear/cytoplasmic fractionation and immunofluorescence demonstrated that YB-1 undergoes nuclear translocation in response to these standard medulloblastoma chemotherapy agents. Chromatin immunoprecipitation (ChIP) analysis of untreated Group 3 cell lines (D283MED and HDMB-03) demonstrated considerable YB-1 interaction with an inverted CCAAT box in the ATP-binding cassette subfamily B member 1 (ABCB1) promoter. RT-PCR analysis of ABCB1 following vincristine and cisplatin treatment revealed differences in transcript expression, indicative of different YB-1 promoter interactions dependent on chemotherapeutic treatment. Our results highlight YB-1 as a novel candidate chemoresistance driver in medulloblastoma.

A CCAAT-binding factor, SlNFYA10, negatively regulates ascorbate accumulation by modulating the d-mannose/l-galactose pathway in tomato

Ascorbic acid (AsA), an important antioxidant and growth regulator, and it is essential for plant development and human health. Specifically, humans have to acquire AsA from dietary sources due to their inability to synthesize it. The AsA biosynthesis pathway in plants has been elucidated, but its regulatory mechanism remains largely unknown. In this report, we biochemically identified a CCAAT-box transcription factor (SlNFYA10) that can bind to the promoter of SlGME1, which encodes GDP-Man-3’,5’-epimerase, a pivotal enzyme in the d-mannose/l-galactose pathway. Importantly, SlNFYA10 simultaneously binds to the promoter of SlGGP1, a downstream gene of SlGME1 in the d-mannose/l-galactose pathway. Binding assays in yeast and functional analyses in plants have confirmed that SlNFYA10 exerts a negative effect on the expression of both SlGME1 and SlGGP1. Transgenic tomato lines overexpressing SlNFYA10 show decreased levels of SlGME1 and SlGGP1 abundance and AsA concentration in their leaves and fruits, accompanied by enhanced sensitivity to oxidative stress. Overall, SlNFYA10 is the first CCAAT-binding factor identified to date to negatively regulate the AsA biosynthetic pathway at multiple sites and modulate plant responses to oxidative stress.

NF-YA Overexpression in Lung Cancer: LUAD

The trimeric transcription factor (TF) NF-Y regulates the CCAAT box, a DNA element enriched in promoters of genes overexpressed in many types of cancer. The regulatory NF-YA is present in two major isoforms, NF-YAl (“long”) and NF-YAs (“short”). There is growing indication that NF-YA levels are increased in tumors. Here, we report interrogation of RNA-Seq TCGA (The Cancer Genome Atlas)—all 576 samples—and GEO (Gene Expression Ominibus) datasets of lung adenocarcinoma (LUAD). NF-YAs is overexpressed in the three subtypes, proliferative, inflammatory, and TRU (terminal respiratory unit). CCAAT is enriched in promoters of tumor differently expressed genes (DEG) and in the proliferative/inflammatory intersection, matching with KEGG (Kyoto Encyclopedia of Genes and Genomes) terms cell-cycle and signaling. Increasing levels of NF-YAs are observed from low to high CpG island methylator phenotypes (CIMP). We identified 166 genes overexpressed in LUAD cell lines with low NF-YAs/NF-YAl ratios: applying this centroid to TCGA samples faithfully predicted tumors’ isoform ratio. This signature lacks CCAAT in promoters. Finally, progression-free intervals and hazard ratios concurred with the worst prognosis of patients with either a low or high NF-YAs/NF-YAl ratio. In conclusion, global overexpression of NF-YAs is documented in LUAD and is associated with aggressive tumor behavior; however, a similar prognosis is recorded in tumors with high levels of NF-YAl and overexpressed CCAAT-less genes.

NF-YA Overexpression in Lung Cancer: LUSC

The CCAAT box is recognized by the trimeric transcription factor NF-Y, whose NF-YA subunit is present in two major splicing isoforms, NF-YAl (“long”) and NF-YAs (“short”). Little is known about the expression levels of NF-Y subunits in tumors, and nothing in lung cancer. By interrogating RNA-seq TCGA and GEO datasets, we found that, unlike NF-YB/NF-YC, NF-YAs is overexpressed in lung squamous cell carcinomas (LUSC). The ratio of the two isoforms changes from normal to cancer cells, with NF-YAs becoming predominant in the latter. NF-YA increased expression correlates with common proliferation markers. We partitioned all 501 TCGA LUSC tumors in the four molecular cohorts and verified that NF-YAs is similarly overexpressed. We analyzed global and subtype-specific RNA-seq data and found that CCAAT is the most abundant DNA matrix in promoters of genes overexpressed in all subtypes. Enriched Gene Ontology terms are cell-cycle and signaling. Survival curves indicate a worse clinical outcome for patients with increasing global amounts of NF-YA; same with hazard ratios with very high and, surprisingly, very low NF-YAs/NF-YAl ratios. We then analyzed gene expression in this latter cohort and identified a different, pro-migration signature devoid of CCAAT. We conclude that overexpression of the NF-Y regulatory subunit in LUSC has the scope of increasing CCAAT-dependent, proliferative (NF-YAshigh) or CCAAT-less, pro-migration (NF-YAlhigh) genes. The data further reinstate the importance of analysis of single isoforms of TFs involved in tumor development.

EDIT-301: An Experimental Autologous Cell Therapy Comprising Cas12a-RNP Modified mPB-CD34+ Cells for the Potential Treatment of SCD

Sickle cell disease (SCD) is an inherited blood disorder affecting approximately 100,000 individuals in the United States. Fetal hemoglobin (HbF) is a major modifier of SCD severity. Studies showed that individuals with compound heterozygosity for sickle hemoglobin (HbS) and hereditary persistence of fetal hemoglobin (HPFH) that expressed approximately 30% HbF did not show features of SCD. Therefore, we are developing EDIT-301, an experimental autologous cell therapy comprising CD34+ cells genetically modified using a Cas12a RNP (ribonucleoprotein) to promote HbF expression to treat SCD. Several HPFH mutations have been reported at the HBG locus. In particular, disruption of the distal CCAAT-box region of the HBG1/2 promoters was associated with elevated levels of HbF, suggesting that this region is a relevant genome editing target for the treatment of SCD. Genotype to phenotype analysis at the distal CCAAT-box region of the HBG1/2 promoters identified the mutations leading to elevated HbF expression. Indels disrupting more than 3 nucleotides were generally associated with elevated HbF expression while smaller indels had lower to no impact. We evaluated editing at this site using several RNP configurations, based on either SpCas9 or Cas12a (also known as Cpf1). Cas12a RNP resulted in larger deletions and a higher frequency of productive indels than SpCas9 RNP. Furthermore, productive indels generated with SpCas9 RNP relied predominantly on microhomology mediated end joining (MMEJ) mechanism. As the MMEJ repair mechanism is not frequently used by hematopoietic stem cells (HSC), productive editing may be low in vivo. In contrast, Cas12a RNP generated more productive indels at the HBG1/2 promoters target site irrespective of the DNA repair mechanism. We therefore postulated that editing at the distal CCAAT-box region with Cas12a would better support long-term persistence of productive indels and robust HbF expression. Consistent with this hypothesis, 80-90% editing was observed after electroporation of mobilized peripheral blood CD34+ cells (mPB-CD34+ cells) from healthy donors with a Cas12a RNP targeting the HBG1/2 promoters, resulting in approximately 40% of HbF expression in their erythroid progeny. Infusion of the modified CD34+ cells into NBSGW mice resulted in long-term multi-lineage reconstitution at 16 weeks post-infusion, with no reduction in editing levels compared to those at the time of infusion. A diverse on-target editing profile was observed in all animals, indicative of a polyclonal engraftment. Erythroid cells purified from the bone marrow of animals that received Cas12a-RNP treated cells demonstrated robust HbF expression averaging 40-50% compared to ~5% observed in the vehicle-treated control group. Off-target activity of the Cas12a RNP was also evaluated. A set of candidate off-target sites was first determined using orthogonal methods, including: in-silico prediction, Digenome-Seq and GUIDE-Seq. Each candidate site was then analyzed for editing by targeted PCR-NGS in electroporated CD34+ cells. No off-target editing was verified, demonstrating the specificity of this Cas12a RNP. Taken together, we identified a specific Cas12a RNP that efficiently edited the distal CCAAT-box region at the HBG1/2 promoters in CD34+ cells. These edited CD34+ cells led to long-term polyclonal multilineage engraftment and therapeutically meaningful levels of 40-50% HbF in vivo. Based on these results, IND-enabling activities have been initiated for EDIT-301: an experimental autologous cell therapy comprising Cas12a-RNP modified mPB-CD34+ cells for the potential treatment of SCD. Disclosures De Dreuzy: Editas Medicine Inc.: Employment, Equity Ownership. Heath:Editas Medicine Inc.: Employment, Equity Ownership. Zuris:Editas Medicine Inc.: Employment, Equity Ownership. Sousa:Editas Medicine Inc.: Employment, Research Funding. Viswanathan:Editas Medicine Inc.: Employment, Equity Ownership. Scott:Editas Medicine Inc.: Employment, Equity Ownership. Da Silva:Editas Medicine Inc.: Employment, Equity Ownership. Ta:Editas Medicine Inc.: Employment, Equity Ownership. Capehart:Editas Medicine Inc.: Equity Ownership. Wang:Editas Medicine Inc.: Employment, Equity Ownership. Fernandez:Editas Medicine Inc.: Employment, Equity Ownership. Myer:Editas Medicine Inc.: Employment, Equity Ownership. Albright:Editas Medicine Inc.: Employment, Equity Ownership. Wilson:Editas Medicine Inc.: Employment, Equity Ownership. Teixeira:Editas Medicine Inc.: Employment, Equity Ownership. Chang:Editas Medicine Inc.: Employment, Equity Ownership.