In pancreatic ductal adenocarcinoma (PDAC), signaling from stromal cells is implicated in metastatic progression. Tumor-stroma cross-talk is often mediated through extracellular vesicles (EVs). We ...previously reported that EVs derived from cancer-associated stromal fibroblasts (CAFs) that are abundant in annexin A6 (ANXA6
EVs) support tumor cell aggressiveness in PDAC. Here, we found that the cell surface glycoprotein and tetraspanin CD9 is a key component of CAF-derived ANXA6
EVs for mediating this cross-talk. CD9 was abundant on the surface of ANXA6
CAFs isolated from patient PDAC samples and from various mouse models of PDAC. CD9 colocalized with CAF markers in the tumor stroma, and CD9 abundance correlated with tumor stage. Blocking CD9 impaired the uptake of ANXA6
EVs into cultured PDAC cells. Signaling pathway arrays and further analyses revealed that the uptake of CD9
ANXA6
EVs induced mitogen-activated protein kinase (MAPK) pathway activity, cell migration, and epithelial-to-mesenchymal transition (EMT). Blocking either CD9 or p38 MAPK signaling impaired CD9
ANXA6
EV-induced cell migration and EMT in PDAC cells. Analysis of bioinformatic datasets indicated that CD9 abundance was an independent marker of poor prognosis in patients with PDAC. Our findings suggest that CD9-mediated stromal cell signaling promotes PDAC progression.
Inducible nitric oxide synthase (iNOS) activity produces anti-tumor and anti-microbial effects but also promotes carcinogenesis through mutagenic, immunosuppressive and pro-angiogenic mechanisms. The ...tumor suppressor p53 contributes to iNOS downregulation by repressing induction of the NOS2 gene encoding iNOS, thereby limiting NO-mediated DNA damages. This study focuses on the role of the p53 homologue TAp73 in the regulation of iNOS expression. Induction of iNOS by immunological stimuli was upregulated in immortalized MEFs from TAp73−/− mice, compared to TAp73+/+ fibroblasts. This overexpression resulted both from increased levels of NOS2 transcripts, and from an increased stability of the protein. Limitation of iNOS expression by TAp73 in wild-type cells is alleviated by TGF-β receptor I inhibitors, suggesting a cooperation between TAp73 and TGF-β in suppression of iNOS expression. Accordingly, downregulation of iNOS expression by exogenous TGF-β1 was impaired in TAp73−/− fibroblasts. Increased NO production in these cells resulted in a stronger, NO-dependent induction of Nrf2 target genes, indicating that the Nrf2-dependent adaptive response to nitrosative stress in fibroblasts is proportional to iNOS activity. NO-dependent induction of two HIF-1 target genes was also stronger in TAp73-deficient cells. Finally, the antimicrobial action of NO against Trypanosoma musculi parasites was enhanced in TAp73−/− fibroblasts. Our data indicate that tumor suppressive TAp73 isoforms cooperate with TGF-β to control iNOS expression, NO-dependent adaptive responses to stress, and pathogen proliferation.
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•Cytokine-induced iNOS expression is increased in TAp73-deficient fibroblasts.•TAp73 cooperates with TGF-β to suppress iNOS transcription and protein expression.•Nrf2-dependent induction of antioxidant genes is enhanced in TAp73 −/− fibroblasts.•NO-dependent upregulation of HIF-1 target genes is stronger in TAp73 −/− fibroblasts.•TAp73 −/− fibroblasts exhibit a higher NO-mediated antimicrobial activity.
Pancreatic ductal adenocarcinoma (PDAC) is characterized by extensive stroma and pathogenic modifications to the peripheral nervous system that elevate metastatic capacity. In this study, we show ...that the IL6-related stem cell-promoting factor LIF supports PDAC-associated neural remodeling (PANR). LIF was overexpressed in tumor tissue compared with healthy pancreas, but its receptors LIFR and gp130 were expressed only in intratumoral nerves. Cancer cells and stromal cells in PDAC tissues both expressed LIF, but only stromal cells could secrete it. Biological investigations showed that LIF promoted the differentiation of glial nerve sheath Schwann cells and induced their migration by activating JAK/STAT3/AKT signaling. LIF also induced neuronal plasticity in dorsal root ganglia neurons by increasing the number of neurites and the soma area. Notably, injection of LIF-blocking antibody into PDAC-bearing mice reduced intratumoral nerve density, supporting a critical role for LIF function in PANR. In serum from human PDAC patients and mouse models of PDAC, we found that LIF titers positively correlated with intratumoral nerve density. Taken together, our findings suggest LIF as a candidate serum biomarker and diagnostic tool and a possible therapeutic target for limiting the impact of PANR in PDAC pathophysiology and metastatic progression.
This study suggests a target to limit neural remodeling in pancreatic cancer, which contributes to poorer quality of life and heightened metastatic progression in patients.
.
Pancreatic ductal adenocarcinoma (PDAC) is extremely stroma‐rich. Cancer‐associated fibroblasts (CAFs) secrete proteins that activate survival and promote chemoresistance of cancer cells. Our results ...demonstrate that CAF secretome‐triggered chemoresistance is abolished upon inhibition of the protein synthesis mTOR/4E‐BP1 regulatory pathway which we found highly activated in primary cultures of α‐SMA‐positive CAFs, isolated from human PDAC resections. CAFs selectively express the sst1 somatostatin receptor. The SOM230 analogue (Pasireotide) activates the sst1 receptor and inhibits the mTOR/4E‐BP1 pathway and the resultant synthesis of secreted proteins including IL‐6. Consequently, tumour growth and chemoresistance in nude mice xenografted with pancreatic cancer cells and CAFs, or with pieces of resected human PDACs, are reduced when chemotherapy (gemcitabine) is combined with SOM230 treatment. While gemcitabine alone has marginal effects, SOM230 is permissive to gemcitabine‐induced cancer cell apoptosis and acts as an antifibrotic agent. We propose that selective inhibition of CAF protein synthesis with sst1‐directed pharmacological compounds represents an anti‐stromal‐targeted therapy with promising chemosensitization potential.
Synopsis
A novel drug association combining current chemotherapies with pharmacological inhibition of the Cancer‐Associated Fibroblast secretome with the somatostatin analogue SOM230 (Pasireotide), effectively reverses chemoresistance in pancreatic cancer.
The secretome of pancreatic cancer‐associated fibroblasts critically contributes to stroma‐triggered chemoresistance.
Elevated PI3K/mTOR pathway activity in pancreatic α‐SMA‐positive cancer‐associated fibroblasts contributes to high protein synthesis/secretion rates.
Inhibition of the protein synthesis mTOR/4E‐BP1 regulatory pathway in pancreatic cancer‐associated fibroblasts, with the novel somatostatin analogue SOM230 (Pasireotide), reverses tumour chemoresistance.
SOM230 selectively targets the somatostatin receptor subtype sst1 in pancreatic α‐SMA‐positive cancer‐associated fibroblasts, which is not expressed in pancreatic non‐activated α‐SMA‐negative fibroblasts or cancer cells.
The combination of chemotherapy (gemcitabine) and pharmacological inhibition of the cancer‐associated fibroblast secretome provides synergistic chemosensitization and tumour growth breakdown.
A novel drug association combining current chemotherapies with pharmacological inhibition of the Cancer‐Associated Fibroblast secretome with the somatostatin analogue SOM230 (Pasireotide), effectively reverses chemoresistance in pancreatic cancer.
Pancreatic ductal adenocarcinoma (PDAC) is extremely stroma-rich. Cancer-associated fibroblasts (CAFs) secrete proteins that activate survival and promote chemoresistance of cancer cells. Our results ...demonstrate that CAF secretome-triggered chemoresistance is abolished upon inhibition of the protein synthesis mTOR/4E-BP1 regulatory pathway which we found highly activated in primary cultures of -SMA-positive CAFs, isolated from human PDAC resections. CAFs selectively express the sst1 somatostatin receptor. The SOM230 analogue (Pasireotide) activates the sst1 receptor and inhibits the mTOR/4E-BP1 pathway and the resultant synthesis of secreted proteins including IL-6. Consequently, tumour growth and chemoresistance in nude mice xenografted with pancreatic cancer cells and CAFs, or with pieces of resected human PDACs, are reduced when chemotherapy (gemcitabine) is combined with SOM230 treatment. While gemcitabine alone has marginal effects, SOM230 is permissive to gemcitabine-induced cancer cell apoptosis and acts as an antifibrotic agent. We propose that selective inhibition of CAF protein synthesis with sst1-directed pharmacological compounds represents an anti-stromal-targeted therapy with promising chemosensitization potential.
The Trp53 gene family member Trp73 encodes two major groups of protein isoforms, TAp73 and DeltaNp73, with opposing pro- and anti-apoptotic functions; consequently, their relative ratio regulates ...cell fate. However, the precise roles of p73 isoforms in cellular events such as tumor initiation, embryonic development, and cell death remain unclear. To determine which aspects of p73 function are attributable to the TAp73 isoforms, we generated and characterized mice in which exons encoding the TAp73 isoforms were specifically deleted to create a TAp73-deficient (TAp73(-/-)) mouse. Here we show that mice specifically lacking in TAp73 isoforms develop a phenotype intermediate between the phenotypes of Trp73(-/-) and Trp53(-/-) mice with respect to incidence of spontaneous and carcinogen-induced tumors, infertility, and aging, as well as hippocampal dysgenesis. In addition, cells from TAp73(-/-) mice exhibit genomic instability associated with enhanced aneuploidy, which may account for the increased incidence of spontaneous tumors observed in these mutants. Hence, TAp73 isoforms exert tumor-suppressive functions and indicate an emerging role for Trp73 in the maintenance of genomic stability.
Mice with a complete deficiency of p73 have severe neurological and immunological defects due to the absence of all TAp73 and DeltaNp73 isoforms. As part of our ongoing program to distinguish the ...biological functions of these isoforms, we generated mice that are selectively deficient for the DeltaNp73 isoform. Mice lacking DeltaNp73 (DeltaNp73(-/-) mice) are viable and fertile but display signs of neurodegeneration. Cells from DeltaNp73(-/-) mice are sensitized to DNA-damaging agents and show an increase in p53-dependent apoptosis. When analyzing the DNA damage response (DDR) in DeltaNp73(-/-) cells, we discovered a completely new role for DeltaNp73 in inhibiting the molecular signal emanating from a DNA break to the DDR pathway. We found that DeltaNp73 localizes directly to the site of DNA damage, can interact with the DNA damage sensor protein 53BP1, and inhibits ATM activation and subsequent p53 phosphorylation. This novel finding may explain why human tumors with high levels of DeltaNp73 expression show enhanced resistance to chemotherapy.
Intercellular communication within pancreatic ductal adenocarcinoma (PDAC) dramatically contributes to metastatic processes. The underlying mechanisms are poorly understood, resulting in a lack of ...targeted therapy to counteract stromal-induced cancer cell aggressiveness. Here, we investigated whether ion channels, which remain understudied in cancer biology, contribute to intercellular communication in PDAC.
We evaluated the effects of conditioned media from patient-derived cancer-associated fibroblasts (CAFs) on electrical features of pancreatic cancer cells (PCC). The molecular mechanisms were deciphered using a combination of electrophysiology, bioinformatics, molecular and biochemistry techniques in cell lines and human samples. An orthotropic mouse model where CAF and PCC were co-injected was used to evaluate tumour growth and metastasis dissemination. Pharmacological studies were carried out in the Pdx1-Cre, Ink4a
LSL
Kras
(KIC
) mouse model.
We report that the K
channel SK2 expressed in PCC is stimulated by CAF-secreted cues (8.84 vs 2.49 pA/pF) promoting the phosphorylation of the channel through an integrin-epidermal growth factor receptor (EGFR)-AKT (Protein kinase B) axis. SK2 stimulation sets a positive feedback on the signalling pathway, increasing invasiveness in vitro (threefold) and metastasis formation in vivo. The CAF-dependent formation of the signalling hub associating SK2 and AKT requires the sigma-1 receptor chaperone. The pharmacological targeting of Sig-1R abolished CAF-induced activation of SK2, reduced tumour progression and extended the overall survival in mice (11.7 weeks vs 9.5 weeks).
We establish a new paradigm in which an ion channel shifts the activation level of a signalling pathway in response to stromal cues, opening a new therapeutic window targeting the formation of ion channel-dependent signalling hubs.
Pancreatic ductal adenocarcinoma (PDA) tumor cells are deprived of oxygen and nutrients and therefore must adapt their metabolism to ensure proliferation. In some physiological states, cells rely on ...ketone bodies to satisfy their metabolic needs, especially during nutrient stress. Here, we show that PDA cells can activate ketone body metabolism and that β‐hydroxybutyrate (βOHB) is an alternative cell‐intrinsic or systemic fuel that can promote PDA growth and progression. PDA cells activate enzymes required for ketogenesis, utilizing various nutrients as carbon sources for ketone body formation. By assessing metabolic gene expression from spontaneously arising PDA tumors in mice, we find HMG‐CoA lyase (HMGCL), involved in ketogenesis, to be among the most deregulated metabolic enzymes in PDA compared to normal pancreas. In vitro depletion of HMGCL impedes migration, tumor cell invasiveness, and anchorage‐independent tumor sphere compaction. Moreover, disrupting HMGCL drastically decreases PDA tumor growth in vivo, while βOHB stimulates metastatic dissemination to the liver. These findings suggest that βOHB increases PDA aggressiveness and identify HMGCL and ketogenesis as metabolic targets for limiting PDA progression.
Synopsis
The molecular mechanisms underlying metabolic flexibility of solid tumor cells exposed to oxygen deprivation remain poorly understood. This study identifies the ketogenic enzyme HMG‐CoA lyase (HMGCL) and its derivative β‐hydroxybutyrate (βOHB) as essential drivers of pancreatic cancer, highlighting ketone body metabolism as a regulatory nexus in metastasis.
Systemic βOHB is metabolized by pancreatic adenocarcinoma (PDA) cells, fueling the TCA cycle.
HMGCL and βOHB promote PDA tumor aggressiveness and metastatic dissemination.
Ketone body metabolic enzymes are upregulated in PDA.
PDA cells de novo generate ketone bodies from various carbon sources.
Depletion of HMGCL limits oncogenic properties of pancreatic tumor cells in vivo, which is rescued by exogenous βOHB.
Systemic and cell‐intrinsic ketone body metabolism supports pancreatic cancer metastasis.
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