Protein kinase D (PKD) family members are increasingly implicated in multiple normal and abnormal biological functions, including signaling pathways that promote mitogenesis in pancreatic cancer. However, nothing is known about the effects of targeting PKD in pancreatic cancer. Our PKD inhibitor discovery program identified CRT0066101 as a specific inhibitor of all PKD isoforms. The aim of our study was to determine the effects of CRT0066101 in pancreatic cancer. Initially, we showed that autophosphorylated PKD1 and PKD2 (activated PKD1/2) are significantly upregulated in pancreatic cancer and that PKD1/2 are expressed in multiple pancreatic cancer cell lines. Using Panc-1 as a model system, we showed that CRT0066101 reduced bromodeoxyuridine incorporation; increased apoptosis; blocked neurotensin-induced PKD1/2 activation; reduced neurotensin-induced, PKD-mediated Hsp27 phosphorylation; attenuated PKD1-mediated NF-κB activation; and abrogated the expression of NF-κB-dependent proliferative and prosurvival proteins. We showed that CRT0066101 given orally (80 mg/kg/d) for 24 days significantly abrogated pancreatic cancer growth in Panc-1 subcutaneous xenograft model. Activated PKD1/2 expression in the treated tumor explants was significantly inhibited with peak tumor concentration (12 μmol/L) of CRT0066101 achieved within 2 hours after oral administration. Further, we showed that CRT0066101 given orally (80 mg/kg/d) for 21 days in Panc-1 orthotopic model potently blocked tumor growth in vivo. CRT0066101 significantly reduced Ki-67-positive proliferation index (P < 0.01), increased terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive apoptotic cells (P < 0.05), and abrogated the expression of NF-κB-dependent proteins including cyclin D1, survivin, and cIAP-1. Our results show for the first time that a PKD-specific small-molecule inhibitor CRT0066101 blocks pancreatic cancer growth in vivo and show that PKD is a novel therapeutic target in pancreatic cancer. Mol Cancer Ther; 9(5); 1136-46. ©2010 AACR.

CXC-chemokines are involved in the chemotaxis of neutrophils, lymphocytes and monocytes. However, role of these chemokines in tumorigenesis, especially with regard to interaction between tumor and its microenvironment, has not been clearly elucidated. The purpose of this study was to analyze the co-operative role of CXCL8 and CXCL12 in the tumor-stromal interaction in pancreatic cancer (PaCa). Using enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR), we initially confirmed the expression of ligands and receptors, respectively, of CXC-chemokines in PaCa and stromal cells. We examined the co-operative role of CXCL8 and CXCL12 in proliferation/invasion of PaCa and human umbilical vein endothelial cells (HUVECs), and in HUVEC tube-formations through tumor-stromal interaction by MTS, Matrigel invasion, and angiogenesis assays, respectively. We detected expression of CXCR4, but not CXCR2, in all PaCa cells and fibroblasts. PaCa cells secreted CXCL8, and fibroblast cells secreted CXCL12. CXCL8 production in PaCa was significantly enhanced by CXCL12, and CXCL12 production in fibroblasts was significantly enhanced by co-culturing with PaCa. CXCL8 enhanced proliferation/invasion of HUVECs but did not promote proliferation/invasion of PaCa. Both recombinant and PaCa-derived CXCL8 enhanced tube formation of HUVECs that were co-cultured with fibroblast cells. CXCL12 enhanced the proliferation/invasion of HUVECs and the invasion of PaCa cells but had no effect on tube formation of HUVEC. We showed that PaCa-derived CXCL8 and fibroblastderived CXCL12 cooperatively induced angiogenesis in vitro by promoting HUVEC proliferation, invasion, and tube formation. Thus, corresponding receptors CXCR2 and CXCR4 are potential antiangiogenic and antimetastatic therapeutic targets in PaCa.

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa secreted acute phase protein, which is also up-regulated in multiple cancers, including breast, lung, and pancreas. Recently, NGAL has been proposed as an early biomarker in pancreatic cancer (PaCa). However, its biological role in PaCa is unknown. In this study, we examined in vitro and in vivo the functional role of NGAL in PaCa. Well-to moderately differentiated PaCa cells (AsPC-1, BxPC-3, and Capan-2) expressed high levels of NGAL but moderately to poorly differentiated PaCa cells (PANC-1 and MIAPaCa-2) expressed undetectable NGAL levels. Immunohistochemistry of untreated tissue microarray showed specific NGAL staining in resected PaCa specimens (P = 0.0167). Stable NGAL overexpression (MIAPaCa-2 and PANC-1) significantly blocked PaCa cell adhesion and invasion in vitro and vice versa with stable PaCa clones (BxPC-3 and AsPC-1). Moreover, NGAL overexpression reduced focal adhesion kinase (FAK) tyrosine-397 phosphorylation in PaCa cells. Furthermore, NGAL overexpression potently decreased angiogenesis in vitro partly through reduced vascular endothelial growth factor (VEGF) production and vice versa. Stable NGAL overexpression or underexpression had no effect on PaCa cell survival, viability, and response to chemotherapeutic drugs. Finally, MIAPaCa-2 cells overexpressing NGAL reduced tumor volume (P = 0.012), local and distant metastasis (P = 0.002), and angiogenesis (P = 0.05) with no effect on K-67 proliferation index (P > 0.1) in an orthotopic nude mouse PaCa model. Collectively, our results suggest that NGAL reduces adhesion/invasion partly by suppressing FAK activation and inhibits angiogenesis partly by blocking VEGF production in PaCa cells. Thus, NGAL is a potential suppressor of invasion and angiogenesis in advanced PaCa. [Cancer Res 2008;68(15):6100-8]

The barrier formed by endothelial cells (ECs) plays an important role in tissue homeostasis by restricting passage of circulating molecules and inflammatory cells. Disruption of the endothelial barrier in pathologic conditions often leads to uncontrolled inflammation and tissue damage. An important component of this barrier is adherens junctions, which restrict paracellular permeability. The transmembrane protein vascular endothelial (VE)-cadherin and its cytoplasmic binding partner b-catenin are major components of functional adherens junctions. We show that mesenchymal stem cells (MSCs) significantly reduce endothelial permeability in cocultured human umbilical vascular endothelial cells (HUVECs) and following exposure to vascular endothelial growth factor, a potent barrier permeability-enhancing agent. When grown in cocultures with HUVECs, MSCs increased VE-cadherin levels and enhanced recruitment of both VE-cadherin and b-catenin to the plasma membrane. Enhanced membrane localization of b-catenin was associated with a decrease in b-catenin-driven gene transcription. Disruption of the VE-cadherin=b-catenin interaction by overexpressing a truncated VE-cadherin lacking the b-catenin interacting domain blocked the permeability-stabilizing effect of MSCs. Interestingly, a conditioned medium from HUVEC-MSC cocultures, but not from HUVEC or MSC cells cultured alone, significantly reduced endothelial permeability. In addition, intravenous administration of MSCs to brain-injured rodents reduced injury-induced enhanced blood-brain barrier permeability. Similar to the effect on in vitro cultures, this stabilizing effect on blood-brain barrier function was associated with increased expression of VEcadherin. Taken together, these results identify a putative mechanism by which MSCs can modulate vascular EC permeability. Further, our results suggest that the mediator(s) of these vascular protective effects is a secreted factor(s) released as a result of direct MSC-EC interaction.

Angiogenesis is essential for tumor growth and metastasis. Although ELR 1 -CXC-chemokines and their corresponding receptor, CXC-receptor 2 (CXCR2), are known mediators of angiogenesis, little is known about their role in pancreatic cancer (PaCa). The aim of our study was to determine the role of ELR 1 -CXCchemokine/CXCR2 biological axis in promoting PaCa angiogenesis. We prospectively collected secretin-stimulated exocrine pancreatic secretions (SSEPS) from normal individuals (NP) and PaCa patients. We showed that summed concentrations of ELR 1 -CXC-chemokines in SSEPS from PaCa patients were significantly higher than in those from NP (p 5 0.002). We measured ELR 1 -CXC-chemokine levels in supernatants from multiple PaCa cell lines and confirmed that BxPC-3, Colo-357 and Panc-28 had significantly higher expression compared with an immortalized human pancreatic ductal epithelial (HPDE) cell line. After confirming lack of autocrine effects of ELR 1 -CXC-chemokines on PaCa cells (due to absence of CXCR2 expression), we investigated paracrine effects of these chemokines on human umbilical vein endothelial cells (HUVEC). Both recombinant ELR 1 -CXC-chemokines and co-culturing with BxPC-3 significantly enhanced proliferation, invasion, and tube formation of HUVEC (p < 0.05). These biological effects were significantly inhibited by treatment with a neutralizing antibody against CXCR2 (anti-CXCR2 Ab) (p < 0.05). Finally, anti-CXCR2 Ab significantly reduced tumor volume (p < 0.05), Ki-67 proliferation index (p 5 0.043) and Factor VIII 1 microvessel density (p 5 0.004) in an orthotopic nude mouse PaCa model. Our results show that ELR 1 -CXC-chemokines promote PaCa tumor-associated angiogenesis through CXCR2, suggesting that CXCR2 is an anti-angiogenic target in PaCa. ' 2009 UICC