No abstract

Gemcitabine is currently the best treatment available for pancreatic cancer, but the disease develops resistance to the drug over time. Agents that can either enhance the effects of gemcitabine or overcome chemoresistance to the drug are needed for the treatment of pancreatic cancer. Curcumin, a component of turmeric (Curcuma longa), is one such agent that has been shown to suppress the transcription factor nuclear factor-KB (NF-KB), which is implicated in proliferation, survival, angiogenesis, and chemoresistance. In this study, we investigated whether curcumin can sensitize pancreatic cancer to gemcitabine in vitro and in vivo. In vitro, curcumin inhibited the proliferation of various pancreatic cancer cell lines, potentiated the apoptosis induced by gemcitabine, and inhibited constitutive NF-KB activation in the cells. In vivo, tumors from nude mice injected with pancreatic cancer cells and treated with a combination of curcumin and gemcitabine showed significant reductions in volume (P = 0.008 versus control; P = 0.036 versus gemcitabine alone), Ki-67 proliferation index (P = 0.030 versus control), NF-KB activation, and expression of NF-KB-regulated gene products (cyclin D1, c-myc, Bcl-2, Bcl-xL, cellular inhibitor of apoptosis protein-1, cyclooxygenase-2, matrix metalloproteinase, and vascular endothelial growth factor) compared with tumors from control mice treated with olive oil only. The combination treatment was also highly effective in suppressing angiogenesis as indicated by a decrease in CD31 + microvessel density (P = 0.018 versus control). Overall, our results suggest that curcumin potentiates the antitumor effects of gemcitabine in pancreatic cancer by suppressing prolifera-

Combination therapy using 8 g oral curcumin daily with gemcitabine-based chemotherapy was safe and feasible in patients with pancreatic cancer and warrants further investigation into its efficacy.

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.