Exocrine pancreas in type 1 and type 2 diabetes: different patterns of fibrosis, metaplasia, angiopathy, and adiposity

The endocrine and exocrine compartments of the pancreas are spatially related but functionally distinct. Multiple diseases affect both compartments, including type 1 diabetes (T1D), pancreatitis, cystic fibrosis, and pancreatic cancer. To better understand how the exocrine pancreas changes with age, obesity, and diabetes, we performed systematic analysis of wellpreserved tissue sections from the pancreatic head, body, and tail of organ donors with T1D (n = 20), type 2 diabetes (T2D, n = 25), and donors with no diabetes (ND, n = 74). Among ND donors, we found that acinar-to-ductal metaplasia (ADM), angiopathy, and pancreatic adiposity increased with age, while ADM and adiposity also increased with BMI. Compared to age- and sex-matched ND organs, T1D pancreata had greater acinar atrophy and angiopathy with fewer intralobular adipocytes. T2D pancreata had greater ADM, angiopathy, and total T lymphocytes, but no difference in adipocyte number, compared to ND organs. While total pancreatic fibrosis was increased in both T1D and T2D, the pattern was different with T1D pancreata having greater periductal and perivascular fibrosis, whereas T2D pancreata had greater lobular and parenchymal fibrosis. Thus, the exocrine pancreas undergoes distinct changes as individuals age or develop T1D or T2D.

Abstract PR02: Profiling intratumoral heterogeneity of bladder cancer subtypes at the single-cell level using machine-learning assisted histopathology

Purpose: Machine-learning assisted histopathology using markers of basal and luminal differentiation was employed to profile the intratumoral heterogeneity of bladder cancer from cystectomy patients and predict disease-free survival in this high-risk patient population.

Methods: Urothelial carcinomas are biologically heterogeneous and vary greatly in clinical progression as well as treatment response. Delineation of molecular subtypes by gene expression analysis of luminal and basal markers has indicated differential outcomes associated with basal and luminal subtypes. However, histologic validation of this classification using protein markers (basal = KRT5/6, P63; luminal = KRT20/GATA3) has been challenging. While using multiplex-immunofluorescence to subtype a retrospective cystectomy cohort (a TMA of 380 patients), we determined that nearly 50% of tumors did not exhibit cytokeratin markers. Subtyping was further confounded by frequent loss of basal-to-luminal stratification and the emergence of intratumoral spatial heterogeneity with the basal and luminal subtypes being completely intermixed throughout the tumor. These observations caused us to hypothesize that previously undefined but clinically relevant subtypes might exist. To address this challenge we developed a single-cell image analysis pipeline that leveraged machine learning to classify molecular subtype and spatial heterogeneity within each tumor. Using the informatics software KNIME we achieved single-cell segmentation and extracted 285 features for 5 protein markers (P63, GATA3, collagen, nuclear stain, and pan-cytokeratin) from each ~20,000 cells contained in 2 cores of tumor and adjacent benign for each patient. Under guidance from a pathologist, definitive urothelial cells (luminal, intermediate, and basal cells) as well as stromal cells were selected from 25 cores normal urothelium to form the ground truth for XGboost-based machine-learning.

Summary Findings: Single-cell profiling with machine learning on transcription factors could classify basal and luminal subtypes with greater than 97% accuracy according to validation in normal urothelium using keratin markers. While we were able to recapitulate differential survival associated with a pure basal subtype, it was the intratumoral heterogeneity of basal and luminal cells that was the predominant driver of disease-free survival.

Conclusion: A newly identified bladder cancer subtype defined by intratumoral heterogeneity is a clinically relevant driver of disease-free survival.

This abstract is also being presented as Poster B22.

Citation Format: Adel Eskaros, Tatiana Novitskaya, Andries Zijlstra. Profiling intratumoral heterogeneity of bladder cancer subtypes at the single-cell level using machine-learning assisted histopathology [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr PR02.

EPHB2 carried on small extracellular vesicles induces tumor angiogenesis via activation of ephrin reverse signaling

Angiogenesis is a key process that allows nutrient uptake and cellular trafficking and is coopted in cancer to enable tumor growth and metastasis. Recently, extracellular vesicles (EVs) have been shown to promote angiogenesis; however, it is unclear what unique features EVs contribute to the process. Here, we studied the role of EVs derived from head and neck squamous cell carcinoma (HNSCC) in driving tumor angiogenesis. Small EVs (SEVs), in the size range of exosomes (50-150 nm), induced angiogenesis both in vitro and in vivo. Proteomic analysis of HNSCC SEVs revealed the cell-to-cell signaling receptor ephrin type B receptor 2 (EPHB2) as a promising candidate cargo to promote angiogenesis. Analysis of patient data further identified EPHB2 overexpression in HNSCC tumors to be associated with poor patient prognosis and tumor angiogenesis, especially in the context of overexpression of the exosome secretion regulator cortactin. Functional experiments revealed that EPHB2 expression in SEVs regulated angiogenesis both in vitro and in vivo and that EPHB2 carried by SEVs stimulates ephrin-B reverse signaling, inducing STAT3 phosphorylation. A STAT3 inhibitor greatly reduced SEV-induced angiogenesis. These data suggest a model in which EVs uniquely promote angiogenesis by transporting Eph transmembrane receptors to nonadjacent endothelial cells to induce ephrin reverse signaling.

Emerin Deregulation Links Nuclear Shape Instability to Metastatic Potential

Abnormalities in nuclear shape are a well-known feature of cancer, but their contribution to malignant progression remains poorly understood. Here, we show that depletion of the cytoskeletal regulator, Diaphanous-related formin 3 (DIAPH3), or the nuclear membrane-associated proteins, lamin A/C, in prostate and breast cancer cells, induces nuclear shape instability, with a corresponding gain in malignant properties, including secretion of extracellular vesicles that contain genomic material. This transformation is characterized by a reduction and/or mislocalization of the inner nuclear membrane protein, emerin. Consistent with this, depletion of emerin evokes nuclear shape instability and promotes metastasis. By visualizing emerin localization, evidence for nuclear shape instability was observed in cultured tumor cells, in experimental models of prostate cancer, in human prostate cancer tissues, and in circulating tumor cells from patients with metastatic disease. Quantitation of emerin mislocalization discriminated cancer from benign tissue and correlated with disease progression in a prostate cancer cohort. Taken together, these results identify emerin as a mediator of nuclear shape stability in cancer and show that destabilization of emerin can promote metastasis.Significance: This study identifies a novel mechanism integrating the control of nuclear structure with the metastatic phenotype, and our inclusion of two types of human specimens (cancer tissues and circulating tumor cells) demonstrates direct relevance to human cancer.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/21/6086/F1.large.jpg Cancer Res; 78(21); 6086-97. ©2018 AACR.

Successful Establishment of Primary Type II Alveolar Epithelium with 3D Organotypic Coculture

Alveolar type II (AT2) epithelial cells are uniquely specialized to produce surfactant in the lung and act as progenitor cells in the process of repair after lung injury. AT2 cell injury has been implicated in several lung diseases, including idiopathic pulmonary fibrosis and bronchopulmonary dysplasia. The inability to maintain primary AT2 cells in culture has been a significant barrier in the investigation of pulmonary biology. We have addressed this knowledge gap by developing a three-dimensional (3D) organotypic coculture using primary human fetal AT2 cells and pulmonary fibroblasts. Grown on top of matrix-embedded fibroblasts, the primary human AT2 cells establish a monolayer and have direct contact with the underlying pulmonary fibroblasts. Unlike conventional two-dimensional (2D) culture, the structural and functional phenotype of the AT2 cells in our 3D organotypic culture was preserved over 7 days of culture, as evidenced by the presence of lamellar bodies and by production of surfactant proteins B and C. Importantly, the AT2 cells in 3D cocultures maintained the ability to replicate, with approximately 60% of AT2 cells staining positive for the proliferation marker Ki67, whereas no such proliferation is evident in 2D cultures of the same primary AT2 cells. This organotypic culture system enables interrogation of AT2 epithelial biology by providing a reductionist in vitro model in which to investigate the response of AT2 epithelial cells and AT2 cell-fibroblast interactions during lung injury and repair.

Alternative splicing of ALCAM enables tunable regulation of cell-cell adhesion through differential proteolysis

While many adhesion receptors are known to influence tumor progression, the mechanisms by which they dynamically regulate cell-cell adhesion remain elusive. We previously identified Activated Leukocyte Cell Adhesion Molecule (ALCAM) as a clinically relevant driver of metastasis and hypothesized that a tunable mechanism of ectodomain shedding regulates its contribution to dissemination. To test this hypothesis, we examined an under-explored ALCAM splice variant (ALCAM-Iso2) and demonstrated that loss of the membrane-proximal region of ALCAM (exon 13) increased metastasis four-fold. Mechanistic studies identified a novel MMP14-dependent membrane distal cleavage site in ALCAM-Iso2, which mediated a ten-fold increase in shedding, thereby decreasing cellular cohesion. Importantly, the loss of cohesion is not limited to the cell capable of shedding because the released extracellular domain diminished cohesion of non-shedding cells through disruption of ALCAM-ALCAM interactions. ALCAM-Iso2-dominated expression in bladder cancer tissue, compared to normal bladder, further emphasizes that ALCAM alternative splicing may contribute to clinical disease progression. The requirement for both the loss of exon 13 and the gain of metalloprotease activity suggests that ALCAM shedding and concomitant regulation of tumor cell adhesion is a locally tunable process.