Marker-free lineage tracing reveals an environment-instructed clonogenic hierarchy in pancreatic cancer.

Effective treatments for pancreatic ductal adenocarcinoma (PDAC) are lacking, and targeted agents have demonstrated limited efficacy. It has been speculated that a rare population of cancer stem cells (CSCs) drives growth, therapy resistance, and rapid metastatic progression in PDAC. These CSCs demonstrate high clonogenicity in vitro and tumorigenic potential in vivo. However, their relevance in established PDAC tissue has not been determined. Here, we use marker-independent stochastic clonal labeling, combined with quantitative modeling of tumor expansion, to uncover PDAC tissue growth dynamics. We find that in contrast to the CSC model, all PDAC cells display clonogenic potential in situ. Furthermore, the proximity to activated cancer-associated fibroblasts determines tumor cell clonogenicity. This means that the microenvironment is dominant in defining the clonogenic activity of PDAC cells. Indeed, manipulating the stroma by Hedgehog pathway inhibition alters the tumor growth mode, revealing that tumor-stroma crosstalk shapes tumor growth dynamics and clonal architecture.

Lodestijn SC ，Miedema DM ，Lenos KJ ，Nijman LE ，Belt SC ，El Makrini K ，Lecca MC ，Waasdorp C ，van den Bosch T ，Bijlsma MF ，Vermeulen L ... -  《Cell Reports》

Signal Transducer and Activator of Transcription 3, Mediated Remodeling of the Tumor Microenvironment Results in Enhanced Tumor Drug Delivery in a Mouse Model of Pancreatic Cancer.

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense desmoplastic reaction (stroma) that impedes drug delivery to the tumor. Attempts to deplete the tumor stroma have resulted in formation of more aggressive tumors. We have identified signal transducer and activator of transcription (STAT) 3 as a biomarker of resistance to cytotoxic and molecularly targeted therapy in PDAC. The purpose of this study is to investigate the effects of targeting STAT3 on the PDAC stroma and on therapeutic resistance. Activated STAT3 protein expression was determined in human pancreatic tissues and tumor cell lines. In vivo effects of AZD1480, a JAK/STAT3 inhibitor, gemcitabine or the combination were determined in Ptf1a(cre/+);LSL-Kras(G12D/+);Tgfbr2(flox/flox) (PKT) mice and in orthotopic tumor xenografts. Drug delivery was analyzed by matrix-assisted laser desorption/ionization imaging mass spectrometry. Collagen second harmonic generation imaging quantified tumor collagen alignment and density. STAT3 activation correlates with decreased survival and advanced tumor stage in patients with PDAC. STAT3 inhibition combined with gemcitabine significantly inhibits tumor growth in both an orthotopic and the PKT mouse model of PDAC. This combined therapy attenuates in vivo expression of SPARC, increases microvessel density, and enhances drug delivery to the tumor without depletion of stromal collagen or hyaluronan. Instead, the PDAC tumors demonstrate vascular normalization, remodeling of the tumor stroma, and down-regulation of cytidine deaminase. Targeted inhibition of STAT3 combined with gemcitabine enhances in vivo drug delivery and therapeutic response in PDAC. These effects occur through tumor stromal remodeling and down-regulation of cytidine deaminase without depletion of tumor stromal content.

Nagathihalli NS ，Castellanos JA ，Shi C ，Beesetty Y ，Reyzer ML ，Caprioli R ，Chen X ，Walsh AJ ，Skala MC ，Moses HL ，Merchant NB ... -  《-》

Pancreatic cancer stem cells may define tumor stroma characteristics and recurrence patterns in pancreatic ductal adenocarcinoma.

Askan G ，Sahin IH ，Chou JF ，Yavas A ，Capanu M ，Iacobuzio-Donahue CA ，Basturk O ，O'Reilly EM ... -  《BMC CANCER》

Direct Interactions With Cancer-Associated Fibroblasts Lead to Enhanced Pancreatic Cancer Stem Cell Function.

Begum A ，McMillan RH ，Chang YT ，Penchev VR ，Rajeshkumar NV ，Maitra A ，Goggins MG ，Eshelman JR ，Wolfgang CL ，Rasheed ZA ，Matsui W ... -  《-》

Autophagy mediates survival of pancreatic tumour-initiating cells in a hypoxic microenvironment.

Involvement of dysregulated autophagy in cancer growth and progression has been shown in different tumour entities, including pancreatic ductal adenocarcinoma (PDA). PDA is an extremely aggressive tumour characterized by a small population of highly therapy-resistant cancer stem cells (CSCs) capable of self-renewal and migration. We examined whether autophagy might be involved in the survival of CSCs despite nutrition and oxygen deprivation typical for the hypoxic tumour microenvironment of PDA. Immunohistochemistry revealed that markers for hypoxia, CSCs and autophagy are co-expressed in patient-derived tissue of PDA. Hypoxia starvation (H/S) enhanced clonogenic survival and migration of established pancreatic cancer cells with stem-like properties (CSC(high)), while pancreatic tumour cells with fewer stem cell markers (CSC(low)) did not survive these conditions. Electron microscopy revealed more advanced autophagic vesicles in CSC(high) cells, which exhibited higher expression of autophagy-related genes under normoxic conditions and relative to CSC(low) cells, as found by RT-PCR and western blot analysis. LC3 was already fully converted to the active LC3-II form in both cell lines, as evaluated by western blot and detection of accumulated GFP-LC3 protein by fluorescence microscopy. H/S increased formation of autophagic and acid vesicles, as well as expression of autophagy-related genes, to a higher extent in CSC(high) cells. Modulation of autophagy by inhibitors and activators resensitized CSC(high) to apoptosis and diminished clonogenicity, spheroid formation, expression of CSC-related genes, migratory activity and tumourigenicity in mice. Our data suggest that enhanced autophagy levels may enable survival of CSC(high) cells under H/S. Interference with autophagy-activating or -inhibiting drugs disturbs the fine-tuned physiological balance of enhanced autophagy in CSC and switches survival signalling to suicide.

Rausch V ，Liu L ，Apel A ，Rettig T ，Gladkich J ，Labsch S ，Kallifatidis G ，Kaczorowski A ，Groth A ，Gross W ，Gebhard MM ，Schemmer P ，Werner J ，Salnikov AV ，Zentgraf H ，Büchler MW ，Herr I ... -  《-》