Pancreatic ductal adenocarcinoma (PDAC) exists in a complex desmoplastic microenvironment, which includes cancer-associated fibroblasts [also known as pancreatic stellate cells (PSC)] and immune cells that provide a fibrotic niche that impedes successful cancer therapy. We have found that mast cells are essential for PDAC tumorigenesis. Whether mast cells contribute to the growth of PDAC and/or PSCs is unknown. Here, we tested the hypothesis that mast cells contribute to the growth of PSCs and tumor cells, thus contributing to PDAC development. Tumor cells promoted mast cell migration. Both tumor cells and PSCs stimulated mast cell activation. Conversely, mast cell–derived interleukin (IL)-13 and tryptase stimulated PSC proliferation. Treating tumor-bearing mice with agents that block mast cell migration and function depressed PDAC growth. Our findings suggest that mast cells exacerbate the cellular and extracellular dynamics of the tumor microenvironment found in PDAC. Therefore, targeting mast cells may inhibit stromal formation and improve therapy. Cancer Res; 73(13); 3927–37. ©2013 AACR.

Advanced pancreatic ductal adenocarcinoma (PDAC) is resistant to therapy, including immune checkpoint inhibitors. We evaluated the effects of a neutralizing antibody against programmed cell death 1 (PD-1) and an agonist of OX40 (provides a survival signal to activated T cells) in mice with pancreatic tumors. We performed studies in C57BL/6 mice (controls), Kras^G12D/+;Trp53^R172H/+;Pdx-1-Cre (KPC) mice, and mice with orthotopic tumors grown from Panc02 cells, Kras^G12D;P53^flox/flox;PDX-1-Cre;Luciferase (KPC-Luc) cells, or mT4 cells. After tumors developed, mice were given injections of control antibody or anti-OX40 and/or anti-PD-1 antibody. Some mice were then given injections of antibodies against CD8, CD4, or NK1.1 to deplete immune cells, and IL4 or IL7RA to block cytokine signaling. Bioluminescence imaging was used to monitor tumor growth. Tumor tissues collected and single-cell suspensions were analyzed by time of flight mass spectrometry analysis. Mice that were tumor-free 100 days after implantation of orthotopic tumors were rechallenged with PDAC cells (KPC-Luc or mT4) and survival was measured. Median levels of PD-1 and OX40 mRNAs in PDACs were determined from The Cancer Genome Atlas and compared with patient survival times. In mice with orthotopic tumors, all those given control antibody or anti-PD-1 died within 50 days, whereas 43% of mice given anti-OX40 survived for 225 days; almost 100% of mice given the combination of anti-PD-1 and anti-OX40 survived for 225 days, and tumors were no longer detected. KPC mice given control antibody, anti-PD-1, or anti-OX40 had median survival times of 50 days or less, whereas mice given the combination of anti-PD-1 and anti-OX40 survived for a median 88 days. Mice with orthotopic tumors that were given the combination of anti-PD-1 and anti-OX40 and survived 100 days were rechallenged with a second tumor; those rechallenged with mT4 cells survived an additional median 70 days and those rechallenged with KPC-Luc cells survived long term, tumor free. The combination of anti-PD-1 and anti-OX40 did not slow tumor growth in mice with antibody-mediated depletion of CD4+ T cells. Mice with orthotopic tumors given the combination of anti-PD-1 and anti-OX40 that survived after complete tumor rejection were rechallenged with KPC-Luc cells; those with depletion of CD4+ T cells before the rechallenge had uncontrolled tumor growth. Furthermore, KPC orthotopic tumors from mice given the combination contained an increased number of CD4+ T cells that expressed CD127 compared with mice given control antibody. The combination of agents reduced the proportion of T-regulatory and exhausted T cells and decreased T-cell expression of GATA3; tumor size was negatively associated with numbers of infiltrating CD4+ T cells, CD4+CD127+ T cells, and CD8+CD127+ T cells, and positively associated with numbers of CD4+PD-1+ T cells, CD4+CD25+ T cells, and CD8+PD-1+ T cells. PDACs with high levels of OX40 and low levels of PD-1 were associated with longer survival times of patients. Pancreatic tumors appear to evade the immune response by inducing development of immune-suppressive T cells. In mice, the combination of anti-PD-1 inhibitory and anti-OX40 agonist antibodies reduces the proportion of T-regulatory and exhausted T cells in pancreatic tumors and increases numbers of memory CD4+ and CD8+ T cells, eradicating all detectable tumor. This information can be used in development of immune-based combination therapies for PDAC.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer death. No effective therapy is currently available for PDAC because of the lack of understanding of the mechanisms leading to its growth and development. Inflammatory cells, particularly mast cells, have been shown to play key roles in some cancers. We carried out this study to test the hypothesis that mast cells in the tumor microenvironment are essential for PDAC tumorigenesis. Experimental Design: The presence of inflammatory cells at various stages of PDAC development was determined in a spontaneous mouse model of PDAC (K-ras^G12V). The importance of mast cells was determined using orthotopically implanted PDAC cells in mast cell–deficient Kit^w-sh/w-sh mice and further confirmed by reconstitution of wild-type bone marrow–derived mast cells. Clinical relevance was assessed by correlating the presence of mast cells with clinical outcome in patients with PDAC. Results: In the spontaneous mouse model of PDAC (K-ras^G12V), there was an early influx of mast cells to the tumor microenvironment. PDAC tumor growth was suppressed in mast cell–deficient Kit^w-sh/w-sh mice, but aggressive PDAC growth was restored when PDAC cells were injected into mast cell–deficient mice reconstituted with wild-type bone marrow–derived mast cells. Mast cell infiltration into the tumor microenvironment was predictive of poor prognosis in patients with PDAC. Conclusions: Mast cells play an important role in PDAC growth and development in mouse models and are indicative of poor prognosis in humans, which makes them a potential novel therapeutic target. Clin Cancer Res; 17(22); 7015–23. ©2011 AACR.

Purpose: The extracellular matrix (ECM) molecule osteopontin is implicated in many pathologic processes, including inflammation, cell proliferation, ECM invasion, tumor progression, and metastasis. The present study evaluated the clinical and biological importance of osteopontin in human lung cancer.

Cell division cycle 20 (CDC20) homolog is an anaphase-promoting complex activator that is essential for cell division, but whether its expression in pancreatic ductal adenocarcinoma (PDAC) is significant is unknown. In this retrospective study, we determined whether aberrant CDC20 expression can be used as a biomarker in pancreatic ductal adenocarcinoma (PDAC) tumorigenesis and whether its expression reflects clinical progression. We compared CDC20 expression levels in normal, cancerous, and inflamed pancreatic tissues from stage II PDAC patients with clinical outcomes and determined CDC20 levels in seven PDAC cell lines. CDC20 was identified using a cDNA microarray database containing gene expression profiles for PDAC tissues and cell lines and chronic pancreatitis and normal pancreas tissues. Its expression was confirmed by real-time quantitative reverse-transcriptase-polymerase chain reaction (qRT-PCR). An immunohistochemical analysis of tissue microarrays from resected PDAC tumors and paired benign pancreatic tissues was done and CDC20 levels were correlated with clinical outcome. Fifty-six patients were included in this study. A microarray analysis revealed 5-fold higher CDC20 expression in PDAC tissue than in chronic pancreatitis tissue. A qRT-PCR analysis confirmed a mean 20-fold higher CDC20 level in PDAC tissue than in normal pancreas and pancreatitis tissue. RNA and protein CDC20 expression was detected in several PDAC cell lines. An immunohistochemical analysis revealed higher CDC20 protein expression levels in PDAC tissue than in normal pancreas tissue, and high CDC20 expression was associated with poor differentiation (P = 0.020) and a significantly lower 5-year recurrence-free survival rate (P = 0.039); we also found a trend toward a shorter overall survival duration. Aberrant CDC20 expression may play an important role in PDAC tumorigenesis and progression and may thus be useful as a marker of disease progression and prognosis and as a therapeutic target.