Clinical and Genomic Characterization of Pancreatic Ductal Adenocarcinoma with Signet-Ring/Poorly Cohesive Cells

Signet-ring cell (SRC)/poorly cohesive cell carcinoma is an aggressive variant of pancreatic ductal adenocarcinoma (PDAC). This study aimed to clarify its clinicopathologic and molecular profiles based on a multi-institutional cohort of 20 cases. The molecular profiles were investigated using DNA and RNA sequencing. The clinicopathologic parameters and molecular alterations were analyzed based on survival indices and using a validation/comparative cohort of 480 conventional PDAC patients. The primary findings were as follows: (1) clinicopathologic features: SRC carcinomas are highly aggressive neoplasms with poor prognosis, and the lungs are elective metastatic sites; (2) survival analysis: a higher SRC component was indicative of poorer prognosis. In particular, the most clinically significant threshold of SRC was 80%, showing statistically significant differences in both disease-specific and disease-free survival; (3) genomic profiles: SRC carcinomas are similar to conventional PDAC with the most common alterations affecting the classic PDAC drivers KRAS (70% of cases), TP53 (55%), SMAD4 (25%), and CDKN2A (20%). EGFR alterations, RET::CCDC6 fusion gene, and microsatellite instability (3 different cases, 1 alteration per case) represent novel targets for precision oncology. The occurrence of SMAD4 mutations was associated with poorer prognosis; (4) pancreatic SRC carcinomas are genetically different from gastric SRC carcinomas: CDH1, the classic driver gene of gastric SRC carcinoma, is not altered in pancreatic SRC carcinoma; (5) transcriptome analysis: the cases clustered into 2 groups, one classical/exocrine-like, and the other squamous-like; and (6) SRC carcinoma-derived organoids can be successfully generated, and their cultures preserve the histologic and molecular features of parental SRC carcinoma. Although pancreatic SRC carcinoma shares similarities with conventional PDAC regarding the most important genetic drivers, it also exhibits important differences. A personalized approach for patients with this tumor type should consider the clinical relevance of histologic determination of the SRC component and the presence of potentially actionable molecular targets.

Extrahepatic Distal Cholangiocarcinoma vs. Pancreatic Ductal Adenocarcinoma: Histology and Molecular Profiling for Differential Diagnosis and Treatment

Pancreatic ductal adenocarcinoma (PDAC) and distal cholangiocarcinoma (dCCA) are very aggressive tumors with a high mortality rate. Pancreas and distal bile ducts share a common embryonic development. Hence, PDAC and dCCA exhibit similar histological features that make a differential diagnosis during routine diagnostic practice challenging. However, there are also significant differences, with potential clinical implications. Even if PDAC and dCCA are generally associated with poor survival, patients with dCCA seem to present a better prognosis. Moreover, although precision oncology-based approaches are still limited in both entities, their most important targets are different and include alterations affecting BRCA1/2 and related genes in PDAC, as well as HER2 amplification in dCCA. Along this line, microsatellite instability represents a potential contact point in terms of tailored treatments, but its prevalence is very low in both tumor types. This review aims at defining the most important similarities and differences in terms of clinicopathological and molecular features between these two entities, also discussing the main theranostic implications derived from this challenging differential diagnosis.

Mechanical activation of Hippo/TGFb pathways lead human saphenous vein progenitors toward pro-fibrotic differentiation in aorto-coronary bypass failure

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ricerca Corrente

Introduction

We previously demonstrated that mechanical stress deriving from coronary flow/pressure patterns in the human saphenous vein (SV) conduits induce release of Thrombospondin-1 (TSP-1) by smooth muscle cells, and this activates adventitial progenitors (SVPs) pathologic activation.

Purpose

In this study, we show a cooperation of the TGF-β/TSP-1 signaling with the mechanically-activated Hippo transcriptional pathway in fibrotic SVPs commitment.

Methods

Human derived-SVPs were isolated using a MACS based protocol with a positive selection for CD34 and a negative depletion of CD31+ cells. We performed an RNA-seq analysis of SVPs subjected to 10% uniaxial deformation (n=5), followed by differential gene expression and pathway analyses. We validated results in vitro and in two animal models of vein arterialization.

Results

A response of SVPs to mechanical stimulation was assessed from variations in cell alignment, circularity and area. The susceptibility of SVPs to uniaxial strain was revealed by a trend of the cells to orientate in orthogonal direction to the strain field and changes in cell shape. Mechanically stimulated cells for 72 hrs showed a significant increase in their motility as verified by migration assays in the presence of medium supplemented with 10% serum. RNA-seq analysis of the total transcriptome expressed in these cells with/without mechanical stimulation was performed. The differentially expressed genes (DEGs) analysis highlighted a maximum variation of the transcriptome at 72hrs of mechanical stimulation vs. static controls with n=819 DEGs. A gene enrichment analysis revealed an involvement of the HIPPO/YAP/TEAD and of the TGF-β/SMAD transcriptional circuitries in mechanically-stimulated cells. In keeping, immunofluorescence and RT-qPCR showed an increase in YAP nuclear translocation and activity. We treated cells with a cytoskeleton inhibitor (Forskolin, FRSK) and a drug (Verteporfin, VTP) that prevents the interaction of the YAP/TAZ complex with TEADs. Both drugs inhibited expression of YAP-transcriptional targets and cellular motility in response to serum. We then treated cells with TGF-β1, TSP-1 alone or in combination. Under these conditions we observed an increased expression of YAP targets and CollA1, a higher amount of Collagen secretion in the supernatant and a higher association of YAP with pSMAD3. All these effects were blunted by VTP. YAP nuclear localization was finally validated in two models of vein arterialization in mice and pigs.

Conclusions

Our data suggest a convergent activation of Hippo/TGF-β pathways in the failure of the aorto-coronary bypass and highlight a future novel strategy to limit its progression in patients.