Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by extensive local invasion and systemic spread. In this study, we employed a three-dimensional organoid model of human pancreatic cancer to characterize the molecular alterations critical for invasion. Time-lapse microscopy was used to observe invasion in organoids from 25 surgically resected human PDAC samples in collagen I. Subsequent lentiviral modification and small-molecule inhibitors were used to investigate the molecular programs underlying invasion in PDAC organoids. When cultured in collagen I, PDAC organoids exhibited two distinct, morphologically defined invasive phenotypes, mesenchymal and collective. Each individual PDAC gave rise to organoids with a predominant phenotype, and PDAC that generated organoids with predominantly mesenchymal invasion showed a worse prognosis. Collective invasion predominated in organoids from cancers with somatic mutations in the driver gene SMAD4 (or its signaling partner TGFBR2). Reexpression of SMAD4 abrogated the col-lective invasion phenotype in SMAD4-mutant PDAC organoids, indicating that SMAD4 loss is required for collective invasion in PDAC organoids. Surprisingly, invasion in passaged SMAD4mutant PDAC organoids required exogenous TGFb, suggesting that invasion in SMAD4-mutant organoids is mediated through noncanonical TGFb signaling. The Rho-like GTPases RAC1 and CDC42 acted as potential mediators of TGFb-stimulated invasion in SMAD4-mutant PDAC organoids, as inhibition of these GTPases suppressed collective invasion in our model. These data suggest that PDAC utilizes different invasion programs depending on SMAD4 status, with collective invasion uniquely present in PDAC with SMAD4 loss.Significance: Organoid models of PDAC highlight the importance of SMAD4 loss in invasion, demonstrating that invasion programs in SMAD4-mutant and SMAD4 wild-type tumors are different in both morphology and molecular mechanism.

The presence of supernumerary centrosomes is prevalent in cancer, where they promote the formation of transient multipolar mitotic spindles. Active clustering of supernumerary centrosomes enables the formation of a functional bipolar spindle that is competent to complete a bipolar division. Disruption of spindle pole clustering in cancer cells promotes multipolar division and generation of non-proliferative daughter cells with compromised viability. Hence molecular pathways required for spindle pole clustering in cells with supernumerary centrosomes, but dispensable in normal cells, are promising therapeutic targets. Here we demonstrate that Aurora A kinase activity is required for spindle pole clustering in cells with extra centrosomes. While cells with two centrosomes are ultimately able to build a bipolar spindle and proceed through a normal cell division in the presence of Aurora A inhibition, cells with supernumerary centrosomes form multipolar and disorganized spindles that are not competent for chromosome segregation. Instead, following a prolonged mitosis, these cells experience catastrophic divisions that result in grossly aneuploid, and non-proliferative daughter cells. Aurora A inhibition in a panel of Acute Myeloid Leukemia cancer cells has a similarly disparate impact on cells with supernumerary centrosomes, suggesting that centrosome number and spindle polarity may serve as predictive biomarkers for response to therapeutic approaches that target Aurora A kinase function.

The presence of supernumerary centrosomes is prevalent in cancer, where they promote the formation of transient multipolar mitotic spindles. Active clustering of supernumerary centrosomes enables the formation of a functional bipolar spindle that is competent to complete a bipolar division. Disruption of spindle pole clustering in cancer cells promotes multipolar division and generation of non-proliferative daughter cells with compromised viability. Hence molecular pathways required for spindle pole clustering in cells with supernumerary centrosomes, but dispensable in normal cells, are promising therapeutic targets. Here we demonstrate that Aurora A kinase activity is required for spindle pole clustering in cells with extra centrosomes. While cells with two centrosomes are ultimately able to build a bipolar spindle and proceed through a normal cell division in the presence of Aurora A inhibition, cells with supernumerary centrosomes form multipolar and disorganized spindles that are not competent for chromosome segregation. Instead, following a prolonged mitosis, these cells experience catastrophic divisions that result in grossly aneuploid, and non-proliferative daughter cells. Aurora A inhibition in a panel of Acute Myeloid Leukemia cancer cells has a similarly disparate impact on cells with supernumerary centrosomes, suggesting that centrosome number and spindle polarity may serve as predictive biomarkers for response to therapeutic approaches that target Aurora A kinase function.

Pancreatic cancer mortality is rising due to late detection and established metastasis. Despite the recent advances in cancer research, metastasis research has been hampered by the lack of models that recapitulate this complex process. Traditional cell culture and animal models provided insights on cancer cell migration and dissemination. But local invasion, which precedes all the events in the metastatic cascade, remains poorly understood. Patient-derived organoids (PDO) present an innovative platform in which the earliest step of metastasis can be observed and manipulated ex vivo. We developed a pancreatic cancer organoid model using surgically resected tumors from The Johns Hopkins Hospital. We previously reported that there are two invasive patterns in pancreatic cancer PDOs - Mesenchymal and Collective invasion, with one dominating pattern in every PDO culture. Here, we describe the gene expression signature associated with local invasion in pancreatic cancer by comparing the whole transcriptome of matched invasive and non-invasive organoids from the same tumor. For this study, PDOs were cultured for 7 days ex vivo and we manually collected 50 invasive and non-invasive organoids from each culture for RNA-seq analysis. To date, the invasive and non-invasive organoids from 6 PDO lines have been analyzed. The list of differentially expressed genes between invasive and non-invasive organoids includes 1,106 genes with FDR 0.001, with DACT1, DKK3 and KIF26B being most differentially expressed. Pathway analysis identifies that the invasive phenotype is associated with extracellular matrix receptor interaction, focal adhesion and PI3K-Akt signaling pathways. In conclusion, our findings revealed a distinct gene expression signature between invasive and non-invasive cells in PDOs. Interestingly, we did not find significant up or down-regulation in the classical EMT markers in our results, which suggests possible pancreatic cancer-specific metastasis programs exist. We believe our results can inform new diagnostic and prognostic tools and help identify anti-metastasis targets in pancreatic cancer. Citation Format: Yea Ji Jeong, Michael G. Lerner, Yuchen Ge, Hildur Knutsdottir, Bernat Navarro-Serer, Peter E. Chianchiano, Andrew J. Ewald, Joel S. Bader, Laura D. Wood. Defining the invasive gene signature using patient derived pancreatic cancer organoids [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 368.

<p>Sequencing Data Quality from Primary FFPE PDAC Samples</p>

<p>Supplementary Video 2. Mesenchymal invasion in PDAC organoid cultured in collagen I (focal invasion).</p>

<p>Evaluation of Sox9 Expression in PDAC Organoids</p>

<p>CK and VIM Expression in Organoids with Mesenchymal and Collective Invasion</p>