Early pancreatic cancer lesions suppress pain through CXCL12-mediated chemoattraction of Schwann cells.

Pancreatic ductal adenocarcinoma (PDAC) cells (PCC) have an exceptional propensity to metastasize early into intratumoral, chemokine-secreting nerves. However, we hypothesized the opposite process, that precancerous pancreatic cells secrete chemokines that chemoattract Schwann cells (SC) of nerves and thus induce ready-to-use routes of dissemination in early carcinogenesis. Here we show a peculiar role for the chemokine CXCL12 secreted in early PDAC and for its receptors CXCR4/CXCR7 on SC in the initiation of neural invasion in the cancer precursor stage and the resulting delay in the onset of PDAC-associated pain. SC exhibited cancer- or hypoxia-induced CXCR4/CXCR7 expression in vivo and in vitro and migrated toward CXCL12-expressing PCC. Glia-specific depletion of CXCR4/CXCR7 in mice abrogated the chemoattraction of SC to PCC. PDAC mice with pancreas-specific CXCL12 depletion exhibited diminished SC chemoattraction to pancreatic intraepithelial neoplasia and increased abdominal hypersensitivity caused by augmented spinal astroglial and microglial activity. In PDAC patients, reduced CXCR4/CXCR7 expression in nerves correlated with increased pain. Mechanistically, upon CXCL12 exposure, SC down-regulated the expression of several pain-associated targets. Therefore, PDAC-derived CXCL12 seems to induce tumor infiltration by SC during early carcinogenesis and to attenuate pain, possibly resulting in delayed diagnosis in PDAC.

Loss of P53 Function Activates JAK2-STAT3 Signaling to Promote Pancreatic Tumor Growth, Stroma Modification, and Gemcitabine Resistance in Mice and Is Associated With Patient Survival.

BACKGROUND & AIMS: One treatment strategy for pancreatic ductal adenocarcinoma is to modify, rather than deplete, the tumor stroma. Constitutive activation of the signal transducer and activator of transcription 3 (STAT3) is associated with progression of pancreatic and other solid tumors. We investigated whether loss of P53 function contributes to persistent activation of STAT3 and modification of the pancreatic tumor stroma in patients and mice. METHODS: Stat3, Il6st (encodes gp130), or Trp53 were disrupted, or a mutant form of P53 (P53R172H) or transgenic sgp130 were expressed, in mice that developed pancreatic tumors resulting from expression of activated KRAS (KrasG12D, KC mice). Pancreata were collected and analyzed by immunohistochemistry, in situ hybridization, quantitative reverse-transcription polymerase chain reaction (qPCR), or immunoblot assays; fluorescence-activated cell sorting was performed to identify immune cells. We obtained frozen pancreatic tumor specimens from patients and measured levels of phosphorylated STAT3 and P53 by immunohistochemistry; protein levels were associated with survival using Kaplan-Meier analyses. We measured levels of STAT3, P53, ligands for gp130, interleukin 6, cytokines, sonic hedgehog signaling, STAT3 phosphorylation (activation), and accumulation of reactive oxygen species in primary pancreatic cells from mice. Mice with pancreatic tumors were given gemcitabine and a Janus kinase 2 (JAK2) inhibitor; tumor growth was monitored by 3-dimensional ultrasound. RESULTS: STAT3 was phosphorylated constitutively in pancreatic tumor cells from KC mice with loss or mutation of P53. Tumor cells of these mice accumulated reactive oxygen species and had lower activity of the phosphatase SHP2 and prolonged phosphorylation of JAK2 compared with tumors from KC mice with functional P53. These processes did not require the gp130 receptor. Genetic disruption of Stat3 in mice, or pharmacologic inhibitors of JAK2 or STAT3 activation, reduced fibrosis and the numbers of pancreatic stellate cells in the tumor stroma and altered the types of immune cells that infiltrated tumors. Mice given a combination of gemcitabine and a JAK2 inhibitor formed smaller tumors and survived longer than mice given control agents; the tumor stroma had fewer activated pancreatic stellate cells, lower levels of periostin, and alterations in collagen production and organization. Phosphorylation of STAT3 correlated with P53 mutation and features of infiltrating immune cells in human pancreatic tumors. Patients whose tumors had lower levels of phosphorylated STAT3 and functional P53 had significantly longer survival times than patients with high levels of phosphorylated STAT3 and P53 mutation. CONCLUSIONS: In pancreatic tumors of mice, loss of P53 function activates JAK2-STAT3 signaling, which promotes modification of the tumor stroma and tumor growth and resistance to gemcitabine. In human pancreatic tumors, STAT3 phosphorylation correlated with P53 mutation and patient survival time. Inhibitors of this pathway slow tumor growth and stroma formation, alter immune cell infiltration, and prolong survival of mice. Transcript profiling: ArrayExpress accession number: E-MTAB-3278.

Activated Schwann cells in pancreatic cancer are linked to analgesia via suppression of spinal astroglia and microglia.

OBJECTIVE: The impact of glia cells during GI carcinogenesis and in cancer pain is unknown. Here, we demonstrate a novel mechanism how Schwann cells (SCs) become activated in the pancreatic cancer (PCa) microenvironment and influence spinal activity and pain sensation. DESIGN: Human SCs were exposed to hypoxia, to pancreatic cancer cells (PCCs) and/or to T-lymphocytes. Both SC and intrapancreatic nerves of patients with PCa with known pain severity were assessed for glial intermediate filament and hypoxia marker expression, proliferation and for transcriptional alterations of pain-related targets. In conditional PCa mouse models with selective in vivo blockade of interleukin (IL)-6 signalling (Ptf1a-Cre;LSL-Kras(G12D)/KC interbred with IL6(-/-) or sgp130(tg) mice), SC reactivity, abdominal mechanosensitivity and spinal glial/neuronal activity were quantified. RESULTS: Tumour hypoxia, PCC and/or T-lymphocytes activated SC via IL-6-signalling in vitro. Blockade of the IL-6-signalling suppressed SC activation around PCa precursor lesions (pancreatic intraepithelial neoplasia (PanIN)) in KC;IL6(-/-) (32.06%±5.25% of PanINs) and KC;sgp130(tg) (55.84%±5.51%) mouse models compared with KC mice (78.27%±3.91%). Activated SCs were associated with less pain in human PCa and with decreased abdominal mechanosensitivity in KC mice (von Frey score of KC: 3.9±0.5 vs KC;IL6(-/-) mice: 5.9±0.9; and KC;sgp130(tg): 10.21±1.4) parallel to attenuation of spinal astroglial and/or microglial activity. Activated SC exhibited a transcriptomic profile with anti-inflammatory and anti-nociceptive features. CONCLUSIONS: Activated SC in PCa recapitulate the hallmarks of 'reactive gliosis' and contribute to analgesia due to suppression of spinal glia. Our findings propose a mechanism for how cancer might remain pain-free via the SC-central glia interplay during cancer progression.

IL-6 trans-signaling promotes pancreatitis-associated lung injury and lethality.

Acute lung injury (ALI) is an inflammatory disease with a high mortality rate. Although typically seen in individuals with sepsis, ALI is also a major complication in severe acute pancreatitis (SAP). The pathophysiology of SAP-associated ALI is poorly understood, but elevated serum levels of IL-6 is a reliable marker for disease severity. Here, we used a mouse model of acute pancreatitis-associated (AP-associated) ALI to determine the role of IL-6 in ALI lethality. Il6-deficient mice had a lower death rate compared with wild-type mice with AP, while mice injected with IL-6 were more likely to develop lethal ALI. We found that inflammation-associated NF-κB induced myeloid cell secretion of IL-6, and the effects of secreted IL-6 were mediated by complexation with soluble IL-6 receptor, a process known as trans-signaling. IL-6 trans-signaling stimulated phosphorylation of STAT3 and production of the neutrophil attractant CXCL1 in pancreatic acinar cells. Examination of human samples revealed expression of IL-6 in combination with soluble IL-6 receptor was a reliable predictor of ALI in SAP. These results demonstrate that IL-6 trans-signaling is an essential mediator of ALI in SAP across species and suggest that therapeutic inhibition of IL-6 may prevent SAP-associated ALI.

Stat3/Socs3 activation by IL-6 transsignaling promotes progression of pancreatic intraepithelial neoplasia and development of pancreatic cancer.

Physiological levels of Kras(G12D) are sufficient to induce pancreatic intraepithelial neoplasias (PanINs); the mechanisms that drive PanIN progression are unknown. Here, we establish that, in addition to oncogenic Kras(G12D), IL-6 transsignaling-dependent activation of Stat3/Socs3 is required to promote PanIN progression and pancreatic ductal adenocarcinoma (PDAC). Myeloid compartment induces Stat3 activation by secreting IL-6; consequently, IL-6 transsignaling activates Stat3 in the pancreas. Using genetic tools, we show that inactivation of IL-6 transsignaling or Stat3 inhibits PanIN progression and reduces the development of PDAC. Aberrant activation of Stat3 through homozygous deletion of Socs3 in the pancreas accelerates PanIN progression and PDAC development. Our data describe the involvement of IL-6 transsignaling/Stat3/Socs3 in PanIN progression and PDAC development.