pki-166 and Pancreatic-Neoplasms

Hypoxia, frequently found in the center of solid tumor, is associated with resistance to chemotherapy by activation of signaling pathways that regulate cell pro-liferation, angiogenesis, and apoptosis. We determined whether hypoxia can increase the resistance of human pancreatic carcinoma cells to gemcitabine-induced apoptosis by activation of phosphatidylinositol 3'-kinase (PI3K)/Akt, MEK/mitogen-activated protein kinase (extracellular signal-regulated kinase) [MAPK(Erk) kinase (MEK)], and nuclear factor kappa B (NF-kappa B) signaling pathways.. We evaluated the phosphorylation of Akt and MAPK(Erk), DNA binding activity of NF-kappa B, and apoptosis induced by gemcitabine in L3.6pl human pancreatic cancer cells under normoxic and hypoxic conditions. We then examined the effects of the PI3K inhibitor LY294002, MEK inhibitor U0126, and the epidermal growth factor receptor tyrosine kinase inhibitor PKI 166 on these signaling pathways and induction of apoptosis.. Hypoxic conditions increased phosphorylation of Akt and MAPK(Erk) and NF-kappa B DNA binding activity in L3.6pl cells. The activation of Akt and NF-kappa B was prevented by LY294002, whereas the activity of MAPK(Erk), but not NF-kappa B, was inhibited by U0126. The increased activation of Akt, NF-kappa B, and MAPK(Erk) was inhibited by PKI 166. Under hypoxic conditions, L3.6pl cells were resistant to apoptosis induced by gemcitabine. The addition of LY294002 or PKI 166 abrogated cell resistance to gemcitabine, whereas U0126 only partially decreased this resistance.. These data demonstrate that hypoxia can induce resistance of pancreatic cancer cells to gemcitabine mainly through the PI3K/Akt/NF-kappa B pathways and partially through the MAPK(Erk) signaling pathway. Because PKI 166 prevented the activation of PI3K/Akt/NF-kappa B and MAPK(Erk) pathways, the combination of this tyrosine kinase inhibitor with gemcitabine should be an effective therapy for pancreatic cancer.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Agents; Apoptosis; Blotting, Western; Butadienes; Cell Division; Cell Line, Tumor; Chromones; Deoxycytidine; Dose-Response Relationship, Drug; Enzyme Inhibitors; Epidermal Growth Factor; ErbB Receptors; Gemcitabine; Humans; Hypoxia; Mitogen-Activated Protein Kinases; Morpholines; Neovascularization, Pathologic; NF-kappa B; Nitriles; Oxygen; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein-Tyrosine Kinases; Pyrimidines; Pyrroles; Signal Transduction; Sp1 Transcription Factor; Time Factors; Tyrosine

We determined whether concurrent blockage of vascular endothelial growth factor (VEGF) receptor and epidermal growth factor (EGF) receptor signaling by two novel tyrosine kinase inhibitors, PTK 787 and PKI 166, respectively, can inhibit angiogenesis and, hence, the growth and metastasis of human pancreatic carcinoma in nude mice. Highly metastatic human pancreatic carcinoma L3.6pl cells were injected into the pancreas of nude mice. Seven days later, groups of mice began receiving oral doses of PTK 787 and PKI 166 three times weekly. Some groups of mice also received i.p. injections of gemcitabine twice a week. The mice were necropsied when the control mice became moribund. Treatment with PTK 787 and PKI 166, with gemcitabine alone, or with the combination of PTK 787, PKI 166, and gemcitabine produced 69, 50, and 97% reduction in the volume of pancreatic tumors, respectively. Administration of protein tyrosine kinase inhibitors and gemcitabine also significantly decreased the incidence of lymph node and liver metastasis. The therapeutic efficacy directly correlated with a decrease in circulating proangiogenic molecules (VEGF, interleukin-8), a decrease in microvessel density, a decrease in proliferating cell nuclear antigen staining, and an increase in apoptosis of tumor cells and endothelial cells. Therapies produced by combining gemcitabine with either PKI 166 or PTK 787 were similar to those produced by combining gemcitabine with both PKI 166 and PTK 787. These results suggest that blockade of either epidermal growth factor receptor or VEGF receptor signaling combined with chemotherapy provides an effective approach to the therapy of pancreatic cancer.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Division; Deoxycytidine; Endothelium, Vascular; ErbB Receptors; Gemcitabine; Humans; Immunohistochemistry; Male; Mice; Mice, Nude; Neoplasm Metastasis; Neovascularization, Pathologic; Pancreatic Neoplasms; Phthalazines; Pyridines; Pyrimidines; Pyrroles; Receptor Protein-Tyrosine Kinases; Receptors, Growth Factor; Receptors, Vascular Endothelial Growth Factor; Signal Transduction; Xenograft Model Antitumor Assays

We determined the optimal administration schedule of a novel epidermal growth factor receptor (EGFR) protein tyrosine kinase inhibitor (PKI), PKI 166 (4-(R)-phenethylamino-6-(hydroxyl)phenyl-7H-pyrrolo[2.3-d]-pyrimidine), alone or in combination with gemcitabine (administered i.p.) for therapy of L3.6pl human pancreatic carcinoma growing in the pancreas of nude mice. Seven days after orthotopic implantation of L3.6pl cells, the mice received daily oral doses of PKI 166. PKI 166 therapy significantly inhibited phosphorylation of the EGFR without affecting EGFR expression. EGFR phosphorylation was restored 72 h after cessation of therapy. Seven days after orthotopic injection of L3.6pl cells, groups of mice received daily or thrice weekly oral doses of PKI 166 alone or in combination with gemcitabine. Treatment with PKI 166 (daily), PKI 166 (3 times/week), or gemcitabine alone produced a 72%, 69%, or 70% reduction in the volume of pancreatic tumors in mice, respectively. Daily oral PKI 166 or thrice weekly oral PKI 166 in combination with injected gemcitabine produced 97% and 95% decreases in volume of pancreatic cancers and significant inhibition of lymph node and liver metastasis. Daily oral PKI 166 produced a 20% decrease in body weight, whereas treatment 3 times/week did not. Decreased microvessel density, decreased proliferating cell nuclear antigen staining, and increased tumor cell and endothelial cell apoptosis correlated with therapeutic success. Collectively, our results demonstrate that three weekly oral administrations of an EGFR tyrosine kinase inhibitor in combination with gemcitabine are sufficient to significantly inhibit primary and metastatic human pancreatic carcinoma.

Topics: Administration, Oral; Animals; Antineoplastic Agents; Cell Division; Deoxycytidine; Drug Administration Schedule; Drug Therapy, Combination; Endothelial Growth Factors; Enzyme Inhibitors; ErbB Receptors; Gemcitabine; Humans; Immunohistochemistry; Interleukin-8; Lymphokines; Male; Mice; Mice, Nude; Neoplasm Metastasis; Pancreatic Neoplasms; Phosphorylation; Platelet Endothelial Cell Adhesion Molecule-1; Proliferating Cell Nuclear Antigen; Pyrimidines; Pyrroles; Ribonucleotide Reductases; Signal Transduction; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors; Xenograft Model Antitumor Assays

We determined whether down-regulation of the epidermal growth factor-receptor (EGF-R) signaling pathway by oral administration of a novel EGF-R tyrosine kinase inhibitor (PKI166) alone or in combination with gemcitabine (administered i.p.) can inhibit growth and metastasis of human pancreatic carcinoma cells implanted into the pancreas of nude mice. Therapy beginning 7 days after orthotopic injection of L3.6pl human pancreatic cancer cells reduced the volume of pancreatic tumors by 59% in mice treated with gemcitabine only, by 45% in those treated with PKI166 only, and by 85% in those given both drugs. The combination therapy also significantly inhibited lymph node and liver metastasis, which led to a significant increase in overall survival. EGF-R activation was significantly blocked by therapy with PKI166 and was associated with significant reduction in tumor cell production of VEGF and IL-8, which in turn correlated with a significant decrease in microvessel density and an increase in apoptotic endothelial cells. Collectively, our results demonstrate that oral administration of an EGF-R tyrosine kinase inhibitor decreased growth and metastasis of human pancreatic cancer growing orthotopically in nude mice and increased survival. The therapeutic effects were mediated in part by inhibition of tumor-induced angiogenesis attributable to a decrease in production of proangiogenic molecules by tumor cells and increased apoptosis of tumor-associated endothelial cells.

Topics: Administration, Oral; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Blotting, Western; Deoxycytidine; Down-Regulation; Endothelium; ErbB Receptors; Fluorescent Antibody Technique; Gemcitabine; Humans; Immunohistochemistry; In Situ Nick-End Labeling; Male; Mice; Mice, Nude; Neoplasm Transplantation; Pancreatic Neoplasms; Platelet Endothelial Cell Adhesion Molecule-1; Protein-Tyrosine Kinases; Pyrimidines; Pyrroles; Signal Transduction; Time Factors; Tumor Cells, Cultured