Non-viral precision T cell receptor replacement for personalized cell therapy.

T cell receptors (TCRs) enable T cells to specifically recognize mutations in cancer cells1-3. Here we developed a clinical-grade approach based on CRISPR-Cas9 non-viral precision genome-editing to simultaneously knockout the two endogenous TCR genes TRAC (which encodes TCRα) and TRBC (which encodes TCRß). We also inserted into the TRAC locus two chains of a neoantigen-specific TCR (neoTCR) isolated from circulating T cells of patients. The neoTCRs were isolated using a personalized library of soluble predicted neoantigen-HLA capture reagents. Sixteen patients with different refractory solid cancers received up to three distinct neoTCR transgenic cell products. Each product expressed a patient-specific neoTCR and was administered in a cell-dose-escalation, first-in-human phase I clinical trial ( NCT03970382 ). One patient had grade 1 cytokine release syndrome and one patient had grade 3 encephalitis. All participants had the expected side effects from the lymphodepleting chemotherapy. Five patients had stable disease and the other eleven had disease progression as the best response on the therapy. neoTCR transgenic T cells were detected in tumour biopsy samples after infusion at frequencies higher than the native TCRs before infusion. This study demonstrates the feasibility of isolating and cloning multiple TCRs that recognize mutational neoantigens. Moreover, simultaneous knockout of the endogenous TCR and knock-in of neoTCRs using single-step, non-viral precision genome-editing are achieved. The manufacture of neoTCR engineered T cells at clinical grade, the safety of infusing up to three gene-edited neoTCR T cell products and the ability of the transgenic T cells to traffic to the tumours of patients are also demonstrated.

Homo- and Heterotypic Association Regulates Signaling by the SgK269/PEAK1 and SgK223 Pseudokinases.

SgK269/PEAK1 is a pseudokinase and scaffolding protein that plays a critical role in regulating growth factor receptor signal output and is implicated in the progression of several cancers, including those of the breast, colon, and pancreas. SgK269 is structurally related to SgK223, a human pseudokinase that also functions as a scaffold but recruits a distinct repertoire of signaling proteins compared with SgK269. Structural similarities between SgK269 and SgK223 include a predicted α-helical region (designated CH) immediately preceding the conserved C-terminal pseudokinase (PK) domain. Structure-function analyses of SgK269 in MCF-10A mammary epithelial cells demonstrated a critical role for the CH and PK regions in promoting cell migration and Stat3 activation. Characterization of the SgK269 "interactome" by mass spectrometry-based proteomics identified SgK223 as a novel binding partner, and association of SgK269 with SgK223 in cells was dependent on the presence of the CH and PK domains of both pseudokinases. Homotypic association of SgK269 and SgK223 was also demonstrated and exhibited the same structural requirements. Further analysis using pulldowns and size-exclusion chromatography underscored the critical role of the CH region in SgK269/SgK223 association. Importantly, although SgK269 bridged SgK223 to Grb2, it was unable to activate Stat3 or efficiently enhance migration in SgK223 knock-out cells generated by CRISPR/Cas9. These results reveal previously unrecognized interplay between two oncogenic scaffolds and demonstrate a novel signaling mechanism for pseudokinases whereby homotypic and heterotypic association is used to assemble scaffolding complexes with distinct binding properties and hence qualitatively regulate signal output.

Resolution of Novel Pancreatic Ductal Adenocarcinoma Subtypes by Global Phosphotyrosine Profiling.

Comprehensive characterization of signaling in pancreatic ductal adenocarcinoma (PDAC) promises to enhance our understanding of the molecular aberrations driving this devastating disease, and may identify novel therapeutic targets as well as biomarkers that enable stratification of patients for optimal therapy. Here, we use immunoaffinity-coupled high-resolution mass spectrometry to characterize global tyrosine phosphorylation patterns across two large panels of human PDAC cell lines: the ATCC series (19 cell lines) and TKCC series (17 cell lines). This resulted in the identification and quantification of over 1800 class 1 tyrosine phosphorylation sites and the consistent segregation of both PDAC cell line series into three subtypes with distinct tyrosine phosphorylation profiles. Subtype-selective signaling networks were characterized by identification of subtype-enriched phosphosites together with pathway and network analyses. This revealed that the three subtypes characteristic of the ATCC series were associated with perturbations in signaling networks associated with cell-cell adhesion and epithelial-mesenchyme transition, mRNA metabolism, and receptor tyrosine kinase (RTK) signaling, respectively. Specifically, the third subtype exhibited enhanced tyrosine phosphorylation of multiple RTKs including the EGFR, ERBB3 and MET. Interestingly, a similar RTK-enriched subtype was identified in the TKCC series, and 'classifier' sites for each series identified using Random Forest models were able to predict the subtypes of the alternate series with high accuracy, highlighting the conservation of the three subtypes across the two series. Finally, RTK-enriched cell lines from both series exhibited enhanced sensitivity to the small molecule EGFR inhibitor erlotinib, indicating that their phosphosignature may provide a predictive biomarker for response to this targeted therapy. These studies highlight how resolution of subtype-selective signaling networks can provide a novel taxonomy for particular cancers, and provide insights into PDAC biology that can be exploited for improved patient management.

Genomic analyses identify molecular subtypes of pancreatic cancer.

Integrated genomic analysis of 456 pancreatic ductal adenocarcinomas identified 32 recurrently mutated genes that aggregate into 10 pathways: KRAS, TGF-ß, WNT, NOTCH, ROBO/SLIT signalling, G1/S transition, SWI-SNF, chromatin modification, DNA repair and RNA processing. Expression analysis defined 4 subtypes: (1) squamous; (2) pancreatic progenitor; (3) immunogenic; and (4) aberrantly differentiated endocrine exocrine (ADEX) that correlate with histopathological characteristics. Squamous tumours are enriched for TP53 and KDM6A mutations, upregulation of the TP63∆N transcriptional network, hypermethylation of pancreatic endodermal cell-fate determining genes and have a poor prognosis. Pancreatic progenitor tumours preferentially express genes involved in early pancreatic development (FOXA2/3, PDX1 and MNX1). ADEX tumours displayed upregulation of genes that regulate networks involved in KRAS activation, exocrine (NR5A2 and RBPJL), and endocrine differentiation (NEUROD1 and NKX2-2). Immunogenic tumours contained upregulated immune networks including pathways involved in acquired immune suppression. These data infer differences in the molecular evolution of pancreatic cancer subtypes and identify opportunities for therapeutic development.

The pseudokinase SgK223 promotes invasion of pancreatic ductal epithelial cells through JAK1/Stat3 signaling.

BACKGROUND: Characterization of molecular mechanisms underpinning development of pancreatic ductal adenocarcinoma (PDAC) may lead to the identification of novel therapeutic targets and biomarkers. SgK223, also known as Pragmin, is a pseudokinase and scaffolding protein closely related to SgK269/PEAK1. Both proteins are implicated in oncogenic tyrosine kinase signaling, but their mechanisms and function remain poorly characterized. METHODS: Expression of SgK223 in PDAC and PDAC cell lines was characterized using gene expression microarrays, mass spectrometry (MS)-based phosphoproteomics and Western blotting. SgK223 was overexpressed in human pancreatic ductal epithelial (HPDE) cells via retroviral transduction, and knocked down in PDAC cells using siRNA. Cell proliferation was determined using a colorimetric cell viability assay, and cell migration and invasion using transwells. Expression of markers of epithelial-mesenchyme transition (EMT) was assayed by quantitative PCR. SgK223 and Stat3 signaling was interrogated by immunoprecipitation, Western blot and gene reporter assays. The functional role of specific kinases and Stat3 was determined using selective small molecule inhibitors. RESULTS: Elevated site-selective tyrosine phosphorylation of SgK223 was identified in subsets of PDAC cell lines, and increased expression of SgK223 detected in several PDAC cell lines compared to human pancreatic ductal epithelial (HPDE) cells and in PDACs compared to normal pancreas. Expression of SgK223 in HPDE cells at levels comparable to those in PDAC did not alter cell proliferation but led to a more elongated morphology, enhanced migration and invasion and induced gene expression changes characteristic of a partial EMT. While SgK223 overexpression did not affect activation of Erk or Akt, it led to increased Stat3 Tyr705 phosphorylation and Stat3 transcriptional activity, and SgK223 and Stat3 associated in vivo. SgK223-overexpressing cells exhibited increased JAK1 activation, and use of selective inhibitors determined that the increased Stat3 signaling driven by SgK223 was JAK-dependent. Pharmacological inhibition of Stat3 revealed that Stat3 activation was required for the enhanced motility and invasion of SgK223-overexpressing cells. CONCLUSIONS: Increased expression of SgK223 occurs in PDAC, and overexpression of SgK223 in pancreatic ductal epithelial cells promotes acquisition of a migratory and invasive phenotype through enhanced JAK1/Stat3 signaling. This represents the first association of SgK223 with a particular human cancer, and links SgK223 with a major signaling pathway strongly implicated in PDAC progression.

Whole genomes redefine the mutational landscape of pancreatic cancer.

Pancreatic cancer remains one of the most lethal of malignancies and a major health burden. We performed whole-genome sequencing and copy number variation (CNV) analysis of 100 pancreatic ductal adenocarcinomas (PDACs). Chromosomal rearrangements leading to gene disruption were prevalent, affecting genes known to be important in pancreatic cancer (TP53, SMAD4, CDKN2A, ARID1A and ROBO2) and new candidate drivers of pancreatic carcinogenesis (KDM6A and PREX2). Patterns of structural variation (variation in chromosomal structure) classified PDACs into 4 subtypes with potential clinical utility: the subtypes were termed stable, locally rearranged, scattered and unstable. A significant proportion harboured focal amplifications, many of which contained druggable oncogenes (ERBB2, MET, FGFR1, CDK6, PIK3R3 and PIK3CA), but at low individual patient prevalence. Genomic instability co-segregated with inactivation of DNA maintenance genes (BRCA1, BRCA2 or PALB2) and a mutational signature of DNA damage repair deficiency. Of 8 patients who received platinum therapy, 4 of 5 individuals with these measures of defective DNA maintenance responded.

Characterization of the novel broad-spectrum kinase inhibitor CTx-0294885 as an affinity reagent for mass spectrometry-based kinome profiling.

Kinase enrichment utilizing broad-spectrum kinase inhibitors enables the identification of large proportions of the expressed kinome by mass spectrometry. However, the existing inhibitors are still inadequate in covering the entire kinome. Here, we identified a novel bisanilino pyrimidine, CTx-0294885, exhibiting inhibitory activity against a broad range of kinases in vitro, and further developed it into a Sepharose-supported kinase capture reagent. Use of a quantitative proteomics approach confirmed the selectivity of CTx-0294885-bound beads for kinase enrichment. Large-scale CTx-0294885-based affinity purification followed by LC-MS/MS led to the identification of 235 protein kinases from MDA-MB-231 cells, including all members of the AKT family that had not been previously detected by other broad-spectrum kinase inhibitors. Addition of CTx-0294885 to a mixture of three kinase inhibitors commonly used for kinase-enrichment increased the number of kinase identifications to 261, representing the largest kinome coverage from a single cell line reported to date. Coupling phosphopeptide enrichment with affinity purification using the four inhibitors enabled the identification of 799 high-confidence phosphosites on 183 kinases, ∼10% of which were localized to the activation loop, and included previously unreported phosphosites on BMP2K, MELK, HIPK2, and PRKDC. Therefore, CTx-0294885 represents a powerful new reagent for analysis of kinome signaling networks that may facilitate development of targeted therapeutic strategies. Proteomics data have been deposited to the ProteomeXchange Consortium ( http://proteomecentral.proteomexchange.org ) via the PRIDE partner repository with the data set identifier PXD000239.

Pancreatic cancer genomes reveal aberrations in axon guidance pathway genes.

Pancreatic cancer is a highly lethal malignancy with few effective therapies. We performed exome sequencing and copy number analysis to define genomic aberrations in a prospectively accrued clinical cohort (n = 142) of early (stage I and II) sporadic pancreatic ductal adenocarcinoma. Detailed analysis of 99 informative tumours identified substantial heterogeneity with 2,016 non-silent mutations and 1,628 copy-number variations. We define 16 significantly mutated genes, reaffirming known mutations (KRAS, TP53, CDKN2A, SMAD4, MLL3, TGFBR2, ARID1A and SF3B1), and uncover novel mutated genes including additional genes involved in chromatin modification (EPC1 and ARID2), DNA damage repair (ATM) and other mechanisms (ZIM2, MAP2K4, NALCN, SLC16A4 and MAGEA6). Integrative analysis with in vitro functional data and animal models provided supportive evidence for potential roles for these genetic aberrations in carcinogenesis. Pathway-based analysis of recurrently mutated genes recapitulated clustering in core signalling pathways in pancreatic ductal adenocarcinoma, and identified new mutated genes in each pathway. We also identified frequent and diverse somatic aberrations in genes described traditionally as embryonic regulators of axon guidance, particularly SLIT/ROBO signalling, which was also evident in murine Sleeping Beauty transposon-mediated somatic mutagenesis models of pancreatic cancer, providing further supportive evidence for the potential involvement of axon guidance genes in pancreatic carcinogenesis.

RON is not a prognostic marker for resectable pancreatic cancer.

BACKGROUND: The receptor tyrosine kinase RON exhibits increased expression during pancreatic cancer progression and promotes migration, invasion and gemcitabine resistance of pancreatic cancer cells in experimental models. However, the prognostic significance of RON expression in pancreatic cancer is unknown. METHODS: RON expression was characterized in several large cohorts, including a prospective study, totaling 492 pancreatic cancer patients and relationships with patient outcome and clinico-pathologic variables were assessed. RESULTS: RON expression was associated with outcome in a training set, but this was not recapitulated in the validation set, nor was there any association with therapeutic responsiveness in the validation set or the prospective study. CONCLUSIONS: Although RON is implicated in pancreatic cancer progression in experimental models, and may constitute a therapeutic target, RON expression is not associated with prognosis or therapeutic responsiveness in resected pancreatic cancer.

Global nucleosome occupancy in yeast.

BACKGROUND: Although eukaryotic genomes are generally thought to be entirely chromatin-associated, the activated PHO5 promoter in yeast is largely devoid of nucleosomes. We systematically evaluated nucleosome occupancy in yeast promoters by immunoprecipitating nucleosomal DNA and quantifying enrichment by microarrays. RESULTS: Nucleosome depletion is observed in promoters that regulate active genes and/or contain multiple evolutionarily conserved motifs that recruit transcription factors. The Rap1 consensus was the only binding motif identified in a completely unbiased search of nucleosome-depleted promoters. Nucleosome depletion in the vicinity of Rap1 consensus sites in ribosomal protein gene promoters was also observed by real-time PCR and micrococcal nuclease digestion. Nucleosome occupancy in these regions was increased by the small molecule rapamycin or, in the case of the RPS11B promoter, by removing the Rap1 consensus sites. CONCLUSIONS: The presence of transcription factor-binding motifs is an important determinant of nucleosome depletion. Most motifs are associated with marked depletion only when they appear in combination, consistent with a model in which transcription factors act collaboratively to exclude nucleosomes and gain access to target sites in the DNA. In contrast, Rap1-binding sites cause marked depletion under steady-state conditions. We speculate that nucleosome depletion enables Rap1 to define chromatin domains and alter them in response to environmental cues.

Rpd3p relocation mediates a transcriptional response to rapamycin in yeast.

Treating yeast cells with rapamycin, a small molecule that inhibits the TOR proteins, leads to the repression of many genes. Consistent with prior studies, we find that RPD3, which encodes a histone deacetylase (HDAC), is required for repression upon rapamycin treatment. To elucidate the mechanism underlying RPD3-mediated repression, we screened all promoters in yeast for occupancy by Rpd3p before and after treatment with rapamycin. We find that Rpd3p binds to the promoters of rapamycin-repressible genes only following treatment. These data conflict with a previously proposed model suggesting that Rpd3p is constitutively bound to rapamycin-repressible genes and becomes active only after a stimulus such as treatment with rapamycin. Rather, the comprehensive analysis presented here strongly supports a model in which recruitment of Rpd3p to gene promoters is a regulated step in the control of gene repression.

Methylation of histone H3 Lys 4 in coding regions of active genes.

Posttranslational modifications of histone tails regulate chromatin structure and transcription. Here we present global analyses of histone acetylation and histone H3 Lys 4 methylation patterns in yeast. We observe a significant correlation between acetylation of histones H3 and H4 in promoter regions and transcriptional activity. In contrast, we find that dimethylation of histone H3 Lys 4 in coding regions correlates with transcriptional activity. The histone methyltransferase Set1 is required to maintain expression of these active, promoter-acetylated, and coding region-methylated genes. Global comparisons reveal that genomic regions deacetylated by the yeast enzymes Rpd3 and Hda1 overlap extensively with Lys 4 hypo- but not hypermethylated regions. In the context of recent studies showing that Lys 4 methylation precludes histone deacetylase recruitment, we conclude that Set1 facilitates transcription, in part, by protecting active coding regions from deacetylation.