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Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy wherein a majority of patients present metastatic disease at diagnosis. Although the role of epithelial to mesenchymal transition (EMT), mediated by transforming growth factor beta (TGFβ), in imparting an aggressive phenotype to PDAC is well documented, the underlying biochemical pathway perturbations driving this behaviour have not been elucidated. We used high-resolution mass spectrometry (HRMS) based molecular phenotyping approach in order to delineate metabolic changes concomitant to TGFβ-induced EMT in pancreatic cancer cells. Strikingly, we observed robust changes in amino acid and energy metabolism that may contribute to tumor invasion and metastasis. Somewhat unexpectedly, TGFβ treatment resulted in an increase in intracellular levels of retinoic acid (RA) that in turn resulted in increased levels of extracellular matrix (ECM) proteins including fibronectin (FN) and collagen (COL1). These findings were further validated in plasma samples obtained from patients with resectable pancreatic cancer. Taken together, these observations provide novel insights into small molecule dysregulation that triggers a molecular cascade resulting in increased EMT-like changes in pancreatic cancer cells, a paradigm that can be potentially targeted for better clinical outcomes.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with limited and, very often, ineffective medical and surgical therapeutic options. The treatment of patients with advanced unresectable PDAC is restricted to systemic chemotherapy, a therapeutic intervention to which most eventually develop resistance. Recently, nab-paclitaxel (n-PTX) has been added to the arsenal of first-line therapies, and the combination of gemcitabine and n-PTX has modestly prolonged median overall survival. However, patients almost invariably succumb to the disease, and little is known about the mechanisms underlying n-PTX resistance. Using the conditionally reprogrammed (CR) cell approach, we established and verified continuously growing cell cultures from treatment-naïve patients with PDAC. To study the mechanisms of primary drug resistance, nab-paclitaxel-resistant (n-PTX-R) cells were generated from primary cultures and drug resistance was verified in vivo, both in zebrafish and in athymic nude mouse xenograft models. Molecular analyses identified the sustained induction of c-MYC in the n-PTX-R cells. Depletion of c-MYC restored n-PTX sensitivity, as did treatment with either the MEK inhibitor, trametinib, or a small-molecule activator of protein phosphatase 2a. IMPLICATIONS: The strategies we have devised, including the patient-derived primary cells and the unique, drug-resistant isogenic cells, are rapid and easily applied in vitro and in vivo platforms to better understand the mechanisms of drug resistance and for defining effective therapeutic options on a patient by patient basis.

Although cancer‐derived extracellular vesicles (cEVs) are thought to play a pivotal role in promoting cancer progression events, their precise effect on neighbouring normal cells is unknown. In this study, we investigated the impact of pancreatic cancer ductal adenocarcinoma (PDAC) derived EVs on recipient non‐tumourigenic pancreatic normal epithelial cells upon internalization. We demonstrate that cEVs are readily internalized and induce endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) in treated normal pancreatic epithelial cells within 24 h. We further show that PDAC cEVs increase cell proliferation, migration, and invasion and that these changes are regulated at least in part, by the UPR mediator DDIT3. Subsequently, these cells release several inflammatory cytokines. Leveraging a layered multi‐omics approach, we analysed EV cargo from a panel of six PDAC and two normal pancreas cell lines, using multiple EV isolation methods. We found that cEVs were enriched for an array of biomolecules which can induce or regulate ER stress and the UPR, including palmitic acid, sphingomyelins, metabolic regulators of tRNA charging and proteins which regulate trafficking and degradation. We further show that palmitic acid, at doses relevant to those found in cEVs, is sufficient to induce ER stress in normal pancreas cells. These results suggest that cEV cargo packaging may be designed to disseminate proliferative and invasive characteristics upon internalization by distant recipient normal cells, hitherto unreported. This study is among the first to highlight a major role for PDAC cEVs to induce stress in treated normal pancreas cells that may modulate a systemic response leading to altered phenotypes. These findings highlight the importance of EVs in mediating disease aetiology and open potential areas of investigation toward understanding the role of cEV lipids in promoting cell transformation in the surrounding microenvironment. [ABSTRACT FROM AUTHOR]

High frequency of mortality in patients with pancreatic ductal adenocarcinoma (PDAC) is vastly associated with the invasive and metastatic nature of these cancer cells. Little is known about the factors involved in this invasive/metastatic process. The current challenge in the treatment of these patients is the lack of viable options besides gemcitabine. The aim of this study was to evaluate the role of PDZ-binding kinase (PBK)/T-LAK cell-originated protein kinase (TOPK) in invasive PDAC cells and to determine whether PBK/TOPK expression drives invasiveness in PDAC. Using gain-of-function and loss-of-function studies in established and patient-derived xenograft–PDAC cell lines, and examining patient-derived archival tissue samples, we demonstrate for the first time that PBK/TOPK is upregulated in pancreatic cancer and expression levels are closely associated with the invasive property of pancreatic cancer cells. Modulation of PBK/TOPK causally regulates the invasive ability of PDAC cells. We also demonstrate that two key players in metastatic invasion, matrix metalloproteinases-2 (MMP-2) and MMP-9 gelatinase activity and gene promoter activities, are regulated by PBK/TOPK. Moreover, we demonstrate for the first time that PBK/TOPK provides stability of an oncoprotein, c-MYC, which transcriptionally regulates MMP-2 and MMP-9 in these invasive PDAC cells. Our in vitro and in situ data corroborate that PBK/TOPK is closely associated with the invasive nature of PDAC and reveal a novel mechanism by which the metastatic behavior of human pancreatic cancer cells is regulated. These findings provide a rationale for targeting PBK/TOPK for the therapeutic intervention of invasive/metastatic pancreatic cancer in human. [ABSTRACT FROM AUTHOR]