Droplet-based proteomics reveals CD36 as a marker for progenitors in mammary basal epithelium.

Deep proteomic profiling of rare cell populations has been constrained by sample input requirements. Here, we present DROPPS (droplet-based one-pot preparation for proteomic samples), an accessible low-input platform that generates high-fidelity proteomic profiles of 100-2,500 cells. By applying DROPPS within the mammary epithelium, we elucidated the connection between mitochondrial activity and clonogenicity, identifying CD36 as a marker of progenitor capacity in the basal cell compartment. We anticipate that DROPPS will accelerate biology-driven proteomic research for a multitude of rare cell populations.

Dipeptidyl-peptidase 9 regulates the dynamics of tumorigenesis and metastasis in breast cancer.

The cytosolic dipeptidyl-aminopeptidase 9 (DPP9) cleaves protein N-termini post-proline or -alanine. Our analysis of DPP9 mRNA expression from the TCGA 'breast cancer' data set revealed that low/intermediate DPP9 levels are associated with poor overall survival of breast cancer patients. To unravel the impact of DPP9 on breast cancer development and progression, the transgenic MMTV-PyMT mouse model of metastasizing breast cancer was used. In addition, tissue- and time-controlled genetic deletion of DPP9 by the Cre-loxP recombination system was done. Despite a delay of tumor onset, a higher number of lung metastases were measured in DPP9-deficient mice compared to controls. In human mammary epithelial cells with oncogenic RAS pathway activation, DPP9 deficiency delayed tumorigenic transformation and accelerated TGF-ß1 induced epithelial-to-mesenchymal transition (EMT) of spheroids. For further analysis of the mechanism, primary breast tumor cells were isolated from the MMTV-PyMT model. DPP9 deficiency in these cells caused cancer cell migration and invasion accompanied by EMT. In absence of DPP9, the EMT transcription factor ZEB1 was stabilized due to insufficient degradation by the proteasome. In summary, low expression of DPP9 appears to decelerate mammary tumorigenesis but favors EMT and metastasis, which establishes DPP9 as a novel dynamic regulator of breast cancer initiation and progression.

Differential DNA damage repair and PARP inhibitor vulnerability of the mammary epithelial lineages.

It is widely assumed that all normal somatic cells can equally perform homologous recombination (HR) and non-homologous end joining in the DNA damage response (DDR). Here, we show that the DDR in normal mammary gland inherently depends on the epithelial cell lineage identity. Bioinformatics, post-irradiation DNA damage repair kinetics, and clonogenic assays demonstrated luminal lineage exhibiting a more pronounced DDR and HR repair compared to the basal lineage. Consequently, basal progenitors were far more sensitive to poly(ADP-ribose) polymerase inhibitors (PARPis) in both mouse and human mammary epithelium. Furthermore, PARPi sensitivity of murine and human breast cancer cell lines as well as patient-derived xenografts correlated with their molecular resemblance to the mammary progenitor lineages. Thus, mammary epithelial cells are intrinsically divergent in their DNA damage repair capacity and PARPi vulnerability, potentially influencing the clinical utility of this targeted therapy.

Hourglass, a rapid analysis framework for heterogeneous bioimaging data, identifies sex disparity in IL-6/STAT3-associated immune phenotypes in pancreatic cancer.

Integration and mining of bioimaging data remains a challenge and lags behind the rapidly expanding digital pathology field. We introduce Hourglass, an open-access analytical framework that streamlines biology-driven visualization, interrogation, and statistical assessment of multiparametric datasets. Cognizant of tissue and clinical heterogeneity, Hourglass systematically organizes observations across spatial and global levels and within patient subgroups. Applied to an extensive bioimaging dataset, Hourglass promptly consolidated a breadth of known interleukin-6 (IL-6) functions via its downstream effector STAT3 and uncovered a so-far unknown sexual dimorphism in the IL-6/STAT3-linked intratumoral T-cell response in human pancreatic cancer. As an R package and cross-platform application, Hourglass facilitates knowledge extraction from multi-layered bioimaging datasets for users with or without computational proficiency and provides unique and widely accessible analytical means to harness insights hidden within heterogeneous tissues at the sample and patient level. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Systemic inflammatory prognostic scores in advanced pancreatic adenocarcinoma.

BACKGROUND: Systemic inflammatory scores may aid prognostication and patient selection for trials. We compared five scores in advanced pancreatic adenocarcinoma (PDAC). METHODS: Unresectable/metastatic PDAC patients enrolled in the Comprehensive Molecular Characterisation of Advanced Pancreatic Ductal Adenocarcinoma for Better Treatment Selection trial (NCT02750657) were included. Patients had pre-treatment biopsies for whole genome and RNA sequencing. CD8 immunohistochemistry was available in a subset. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio, Prognostic Nutritional Index, Gustave Roussy Immune Score (GRIm-S), and Memorial Sloan Kettering Prognostic Score (MPS) were calculated. Overall survival (OS) was estimated using Kaplan-Meier methods. Associations between inflammatory scores, clinical/genomic characteristics, and OS were analysed. RESULTS: We analysed 263 patients. High-risk NLR, GRIm-S and MPS were poorly prognostic. The GRIm-S had the highest predictive ability: median OS 6.4 vs. 10 months for high risk vs. low-risk (P < 0.001); HR 2.26 (P < 0.001). ECOG ≥ 1, the basal-like subtype, and low-HRDetect were additional poor prognostic factors (P < 0.01). Inflammatory scores did not associate with RNA-based classifiers or homologous recombination repair deficiency genotypes. High-risk MPS (P = 0.04) and GRIm-S (P = 0.02) patients had lower median CD8 + tumour-infiltrating lymphocytes. CONCLUSIONS: Inflammatory scores incorporating NLR have prognostic value in advanced PDAC. Understanding immunophenotypes of poor-risk patients and using these scores in trials will advance the field.

Correlation of transcriptional subtypes with a validated CT radiomics score in resectable pancreatic ductal adenocarcinoma.

OBJECTIVES: Transcriptional classifiers (Bailey, Moffitt and Collison) are key prognostic factors of pancreatic ductal adenocarcinoma (PDAC). Among these classifiers, the squamous, basal-like, and quasimesenchymal subtypes overlap and have inferior survival. Currently, only an invasive biopsy can determine these subtypes, possibly resulting in treatment delay. This study aimed to investigate the association between transcriptional subtypes and an externally validated preoperative CT-based radiomic prognostic score (Rad-score). METHODS: We retrospectively evaluated 122 patients who underwent resection for PDAC. All treatment decisions were determined at multidisciplinary tumor boards. Tumor Rad-score values from preoperative CT were dichotomized into high or llow categories. The primary endpoint was the correlation between the transcriptional subtypes and the Rad-score using multivariable linear regression, adjusting for clinical and histopathological variables (i.e., tumor size). Prediction of overall survival (OS) was secondary endpoint. RESULTS: The Bailey transcriptional classifier significantly associated with the Rad-score (coefficient = 0.31, 95% confidence interval [CI]: 0.13-0.44, p = 0.001). Squamous subtype was associated with high Rad-scores while non-squamous subtype was associated with low Rad-scores (adjusted p = 0.03). Squamous subtype and high Rad-score were both prognostic for OS at multivariable analysis with hazard ratios (HR) of 2.79 (95% CI: 1.12-6.92, p = 0.03) and 4.03 (95% CI: 1.42-11.39, p = 0.01), respectively. CONCLUSIONS: In patients with resectable PDAC, an externally validated prognostic radiomic model derived from preoperative CT is associated with the Bailey transcriptional classifier. Higher Rad-scores were correlated with the squamous subtype, while lower Rad-scores were associated with the less lethal subtypes (immunogenic, ADEX, pancreatic progenitor). KEY POINTS: • The transcriptional subtypes of PDAC have been shown to have prognostic importance but they require invasive biopsy to be assessed. • The Rad-score radiomic biomarker, which is obtained non-invasively from preoperative CT, correlates with the Bailey squamous transcriptional subtype and both are negative prognostic biomarkers. • The Rad-score is a promising non-invasive imaging biomarker for personalizing neoadjuvant approaches in patients undergoing resection for PDAC, although additional validation studies are required.

Glycoproteomics Identifies Plexin-B3 as a Targetable Cell Surface Protein Required for the Growth and Invasion of Triple-Negative Breast Cancer Cells.

Driven by the lack of targeted therapies, triple-negative breast cancers (TNBCs) have the worst overall survival of all breast cancer subtypes. Considering that cell surface proteins are favorable drug targets and are predominantly glycosylated, glycoproteome profiling has significant potential to facilitate the identification of much-needed drug targets for TNBCs. Here, we performed N-glycoproteomics on six TNBCs and five normal control (NC) cell lines using hydrazide-based enrichment. Quantitative proteomics and integrative data mining led to the discovery of Plexin-B3 (PLXNB3), a previously undescribed TNBC-enriched cell surface protein. Furthermore, siRNA knockdown and CRISPR-Cas9 editing of in vitro and in vivo models show that PLXNB3 is required for TNBC cell line growth, invasion, and migration. Altogether, we provide insights into N-glycoproteome remodeling associated with TNBCs and functional evaluation of an extracted target, which indicate the surface protein PLXNB3 as a potential therapeutic target for TNBCs.

Modification of BRCA1-associated breast cancer risk by HMMR overexpression.

Breast cancer risk for carriers of BRCA1 pathological variants is modified by genetic factors. Genetic variation in HMMR may contribute to this effect. However, the impact of risk modifiers on cancer biology remains undetermined and the biological basis of increased risk is poorly understood. Here, we depict an interplay of molecular, cellular, and tissue microenvironment alterations that increase BRCA1-associated breast cancer risk. Analysis of genome-wide association results suggests that diverse biological processes, including links to BRCA1-HMMR profiles, influence risk. HMMR overexpression in mouse mammary epithelium increases Brca1-mutant tumorigenesis by modulating the cancer cell phenotype and tumor microenvironment. Elevated HMMR activates AURKA and reduces ARPC2 localization in the mitotic cell cortex, which is correlated with micronucleation and activation of cGAS-STING and non-canonical NF-κB signaling. The initial tumorigenic events are genomic instability, epithelial-to-mesenchymal transition, and tissue infiltration of tumor-associated macrophages. The findings reveal a biological foundation for increased risk of BRCA1-associated breast cancer.

Tryptophan-derived microbial metabolites activate the aryl hydrocarbon receptor in tumor-associated macrophages to suppress anti-tumor immunity.

The aryl hydrocarbon receptor (AhR) is a sensor of products of tryptophan metabolism and a potent modulator of immunity. Here, we examined the impact of AhR in tumor-associated macrophage (TAM) function in pancreatic ductal adenocarcinoma (PDAC). TAMs exhibited high AhR activity and Ahr-deficient macrophages developed an inflammatory phenotype. Deletion of Ahr in myeloid cells or pharmacologic inhibition of AhR reduced PDAC growth, improved efficacy of immune checkpoint blockade, and increased intra-tumoral frequencies of IFNγ+CD8+ T cells. Macrophage tryptophan metabolism was not required for this effect. Rather, macrophage AhR activity was dependent on Lactobacillus metabolization of dietary tryptophan to indoles. Removal of dietary tryptophan reduced TAM AhR activity and promoted intra-tumoral accumulation of TNFα+IFNγ+CD8+ T cells; provision of dietary indoles blocked this effect. In patients with PDAC, high AHR expression associated with rapid disease progression and mortality, as well as with an immune-suppressive TAM phenotype, suggesting conservation of this regulatory axis in human disease.

Spatially confined sub-tumor microenvironments in pancreatic cancer.

Intratumoral heterogeneity is a critical frontier in understanding how the tumor microenvironment (TME) propels malignant progression. Here, we deconvolute the human pancreatic TME through large-scale integration of histology-guided regional multiOMICs with clinical data and patient-derived preclinical models. We discover "subTMEs," histologically definable tissue states anchored in fibroblast plasticity, with regional relationships to tumor immunity, subtypes, differentiation, and treatment response. "Reactive" subTMEs rich in complex but functionally coordinated fibroblast communities were immune hot and inhabited by aggressive tumor cell phenotypes. The matrix-rich "deserted" subTMEs harbored fewer activated fibroblasts and tumor-suppressive features yet were markedly chemoprotective and enriched upon chemotherapy. SubTMEs originated in fibroblast differentiation trajectories, and transitory states were notable both in single-cell transcriptomics and in situ. The intratumoral co-occurrence of subTMEs produced patient-specific phenotypic and computationally predictable heterogeneity tightly linked to malignant biology. Therefore, heterogeneity within the plentiful, notorious pancreatic TME is not random but marks fundamental tissue organizational units.

Abnormal B-cell development in TIMP-deficient bone marrow.

Bone marrow (BM) is the primary site of hematopoiesis and is responsible for a lifelong supply of all blood cell lineages. The process of hematopoiesis follows key intrinsic programs that also integrate instructive signals from the BM niche. First identified as an erythropoietin-potentiating factor, the tissue inhibitor of metalloproteinase (TIMP) protein family has expanded to 4 members and has widely come to be viewed as a classical regulator of tissue homeostasis. By virtue of metalloprotease inhibition, TIMPs not only regulate extracellular matrix turnover but also control growth factor bioavailability. The 4 mammalian TIMPs possess overlapping enzyme-inhibition profiles and have never been studied for their cumulative role in hematopoiesis. Here, we show that TIMPs are critical for postnatal B lymphopoiesis in the BM. TIMP-deficient mice have defective B-cell development arising at the pro-B-cell stage. Expression analysis of TIMPless hematopoietic cell subsets pointed to an altered B-cell program in the Lineage-Sca-1+c-Kit+ (LSK) cell fraction. Serial and competitive BM transplants identified a defect in TIMP-deficient hematopoietic stem and progenitor cells for B lymphopoiesis. In parallel, reverse BM transplants uncovered the extrinsic role of stromal TIMPs in pro- and pre-B-cell development. TIMP deficiency disrupted CXCL12 localization to LepR+ cells, and increased soluble CXCL12 within the BM niche. It also compromised the number and morphology of LepR+ cells. These data provide new evidence that TIMPs control the cellular and biochemical makeup of the BM niche and influence the LSK transcriptional program required for optimal B lymphopoiesis.

TIMP1 expression underlies sex disparity in liver metastasis and survival in pancreatic cancer.

Sex disparity in cancer is so far inadequately considered, and components of its basis are rather unknown. We reveal that male versus female pancreatic cancer (PC) patients and mice show shortened survival, more frequent liver metastasis, and elevated hepatic metastasis-promoting gene expression. Tissue inhibitor of metalloproteinases 1 (TIMP1) was the secreted factor with the strongest male-biased expression in patient-derived pancreatic tumors. Male-specific up-regulation of systemic TIMP1 was demonstrated in PC mouse models and patients. Using TIMP1-competent and TIMP1-deficient PC mouse models, we established a causal role of TIMP1 in determining shortened survival and increased liver metastasis in males. Observing TIMP1 expression as a risk parameter in males led to identification of a subpopulation exhibiting increased TIMP1 levels (T1HI males) in both primary tumors and blood. T1HI males showed increased risk for liver metastasis development not only in PC but also in colorectal cancer and melanoma. This study reveals a lifestyle-independent sex disparity in liver metastasis and may open new avenues toward precision medicine.

Mammary epithelial cells have lineage-rooted metabolic identities.

Cancer metabolism adapts the metabolic network of its tissue of origin. However, breast cancer is not a disease of a single origin. Multiple epithelial populations serve as the culprit cell of origin for specific breast cancer subtypes, yet our knowledge of the metabolic network of normal mammary epithelial cells is limited. Using a multi-omic approach, here we identify the diverse metabolic programmes operating in normal mammary populations. The proteomes of basal, luminal progenitor and mature luminal cell populations revealed enrichment of glycolysis in basal cells and of oxidative phosphorylation in luminal progenitors. Single-cell transcriptomes corroborated lineage-specific metabolic identities and additional intra-lineage heterogeneity. Mitochondrial form and function differed across lineages, with clonogenicity correlating with mitochondrial activity. Targeting oxidative phosphorylation and glycolysis with inhibitors exposed lineage-rooted metabolic vulnerabilities of mammary progenitors. Bioinformatics indicated breast cancer subtypes retain metabolic features of their putative cell of origin. Thus, lineage-rooted metabolic identities of normal mammary cells may underlie breast cancer metabolic heterogeneity and targeting these vulnerabilities could advance breast cancer therapy.

GATA6 Expression Distinguishes Classical and Basal-like Subtypes in Advanced Pancreatic Cancer.

PURPOSE: To determine the impact of basal-like and classical subtypes in advanced pancreatic ductal adenocarcinoma (PDAC) and to explore GATA6 expression as a surrogate biomarker. EXPERIMENTAL DESIGN: Within the COMPASS trial, patients proceeding to chemotherapy for advanced PDAC undergo tumor biopsy for RNA-sequencing (RNA-seq). Overall response rate (ORR) and overall survival (OS) were stratified by subtypes and according to chemotherapy received. Correlation of GATA6 with the subtypes using gene expression profiling, in situ hybridization (ISH) was explored. RESULTS: Between December 2015 and May 2019, 195 patients (95%) had enough tissue for RNA-seq; 39 (20%) were classified as basal-like and 156 (80%) as classical. RECIST response data were available for 157 patients; 29 basal-like and 128 classical where the ORR was 10% versus 33%, respectively (P = 0.02). In patients with basal-like tumors treated with modified FOLFIRINOX (n = 22), the progression rate was 60% compared with 15% in classical PDAC (P = 0.0002). Median OS in the intention-to-treat population (n = 195) was 9.3 months for classical versus 5.9 months for basal-like PDAC (HR, 0.47; 95% confidence interval, 0.32-0.69; P = 0.0001). GATA6 expression by RNA-seq highly correlated with the classifier (P < 0.001) and ISH predicted the subtypes with sensitivity of 89% and specificity of 83%. In a multivariate analysis, GATA6 expression was prognostic (P = 0.02). In exploratory analyses, basal-like tumors, could be identified by keratin 5, were more hypoxic and enriched for a T-cell-inflamed gene expression signature. CONCLUSIONS: The basal-like subtype is chemoresistant and can be distinguished from classical PDAC by GATA6 expression.See related commentary by Collisson, p. 4715.

Author Correction: Human somatic cell mutagenesis creates genetically tractable sarcomas.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A Four-Chemokine Signature Is Associated with a T-cell-Inflamed Phenotype in Primary and Metastatic Pancreatic Cancer.

PURPOSE: The molecular drivers of antitumor immunity in pancreatic ductal adenocarcinoma (PDAC) are poorly understood, posing a major obstacle for the identification of patients potentially amenable for immune-checkpoint blockade or other novel strategies. Here, we explore the association of chemokine expression with effector T-cell infiltration in PDAC. EXPERIMENTAL DESIGN: Discovery cohorts comprised 113 primary resected PDAC and 107 PDAC liver metastases. Validation cohorts comprised 182 PDAC from The Cancer Genome Atlas and 92 PDACs from the Australian International Cancer Genome Consortium. We explored associations between immune cell counts by immunohistochemistry, chemokine expression, and transcriptional hallmarks of antitumor immunity by RNA sequencing (RNA-seq), and mutational burden by whole-genome sequencing. RESULTS: Among all known human chemokines, a coregulated set of four (CCL4, CCL5, CXCL9, and CXCL10) was strongly associated with CD8+ T-cell infiltration (P < 0.001). Expression of this "4-chemokine signature" positively correlated with transcriptional metrics of T-cell activation (ZAP70, ITK, and IL2RB), cytolytic activity (GZMA and PRF1), and immunosuppression (PDL1, PD1, CTLA4, TIM3, TIGIT, LAG3, FASLG, and IDO1). Furthermore, the 4-chemokine signature marked tumors with increased T-cell activation scores (MHC I presentation, T-cell/APC costimulation) and elevated expression of innate immune sensing pathways involved in T-cell priming (STING and NLRP3 inflammasome pathways, BATF3-driven dendritic cells). Importantly, expression of this 4-chemokine signature was consistently indicative of a T-cell-inflamed phenotype across primary PDAC and PDAC liver metastases. CONCLUSIONS: A conserved 4-chemokine signature marks resectable and metastatic PDAC tumors with an active antitumor phenotype. This could have implications for the appropriate selection of PDAC patients in immunotherapy trials.

Metalloproteases: On the Watch in the Hematopoietic Niche.

Hematopoietic stem cells (HSCs) self-renew or differentiate into blood cell lineages following extrinsic cues propagated in specialized niches. Support cells and soluble factors in the niche respond to stress and enable progenitor activity. Metalloproteases (MMPs, ADAMs, ADAMTSs) and their inhibitors (TIMPs) control certain physical and biochemical features of the niche by altering protease-dependent bioavailability of local niche factors (e.g., CXCL12, SCF, TGFß, VEGF), matrix turnover, and cellular interactions. With over 40 examples of diverse metalloprotease substrates known to trigger fate-changing decisions, the spatially confined activity of this multi-member protease family is ideally positioned to constitute a higher order control over hematopoiesis. Comprehension of regulated proteolysis in the bone marrow may fuel innovative strategies to harness HSC fate and function.