pki-166 and Neoplasm-Metastasis

The failure to treat metastatic cancer with multidrug resistance is a major problem for successful cancer therapy, and the molecular basis for the association of metastatic phenotype with resistance to therapy is still unclear. In this study, we revealed that various metastatic cancer cells showed consistently higher levels of antiapoptotic proteins, including Bcl-2, nuclear factor-kappaB, MDM2, DNA-dependent protein kinase (DNA-PK), and epidermal growth factor receptor (EGFR), and lower levels of proapoptotic proteins, including Bax and p53 than low metastatic parental cells. This was followed by chemo- and radioresistance in metastatic cancer cells compared with their parental cells. EGFR and DNA-PK activity, which are known to be associated with chemo- and radioresistance, were demonstrated to be mutually regulated by each other. Treatment with PKI166, an EGFR inhibitor, suppressed etoposide-induced activation of DNA-PK in A375SM metastatic melanoma cells. In addition, PKI166 enhanced markedly the chemosensitivities of metastatic cancer cell sublines to various anticancer drugs in comparison with those of low metastatic cancer cells. These results suggest that the activities of DNA-PK and EGFR, which is positively correlated with each other, may contribute to metastatic phenotype as well as therapy resistance, and the EGFR inhibitor enhances the effect of anticancer drugs against therapy-resistant metastatic cancer cells via suppression of stress responses, including activation of DNA-PK.

Topics: Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Apoptosis; Blotting, Western; Cell Line, Tumor; DNA-Activated Protein Kinase; DNA-Binding Proteins; Drug Synergism; Electrophoretic Mobility Shift Assay; ErbB Receptors; Etoposide; Genes, MDR; Humans; Indicators and Reagents; Melanoma; Neoplasm Metastasis; Nuclear Proteins; Protein Serine-Threonine Kinases; Pyrimidines; Pyrroles; Radiation-Sensitizing Agents; Rats

We determined whether blockade of the epidermal growth factor receptor (EGF-R) signaling pathway by oral administration of the EGF-R tyrosine kinase inhibitor (PKI 166) alone or in combination with injectable Taxol inhibits the growth of PC-3MM2 human prostate cancer cells in the bone of nude mice.. Male nude mice implanted with PC-3MM2 cells in the tibia were treated with oral administrations of PKI 166 or PKI 166 plus injectable Taxol beginning 3 days after implantation. The incidence and size of bone tumors and destruction of bone were determined by digitalized radiography. Expression of epidermal growth factor (EGF), EGF-R, and activated EGF-R in tumor cells and tumor-associated endothelial cells was determined by immunohistochemistry.. Oral administration of PKI 166 or PKI 166 plus injectable Taxol reduced the incidence and size of bone tumors and destruction of bone. Immunohistochemical analysis revealed that PC-3MM2 cells growing adjacent to the bone expressed high levels of EGF and activated EGF-R, whereas tumor cells in the adjacent musculature did not. Moreover, endothelial cells within the bone tumor lesions, but not in uninvolved bone or tumors in the muscle, expressed high levels of activated EGF-R. Treatment with PKI 166 and more so with PKI 166 plus Taxol significantly inhibited phosphorylation of EGF-R on tumor and endothelial cells and induced significant apoptosis and endothelial cells within tumor lesions.. These data indicate that endothelial cells exposed to EGF produced by tumor cells express activated EGF-R and that targeting EGF-R can produce significant therapeutic effects against prostate cancer bone metastasis.

Topics: Administration, Oral; Animals; Antineoplastic Agents, Phytogenic; Blotting, Western; Bone and Bones; Bone Neoplasms; Dose-Response Relationship, Drug; Endothelial Growth Factors; Endothelium, Vascular; ErbB Receptors; Fibroblast Growth Factor 2; Immunohistochemistry; In Situ Nick-End Labeling; Intercellular Signaling Peptides and Proteins; Interleukin-8; Lymphokines; Male; Mice; Mice, Nude; Microscopy, Fluorescence; Neoplasm Metastasis; Neoplasm Transplantation; Paclitaxel; Phosphorylation; Platelet Endothelial Cell Adhesion Molecule-1; Proliferating Cell Nuclear Antigen; Prostatic Neoplasms; Pyrimidines; Pyrroles; Signal Transduction; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

We determined whether blockade of the epidermal growth factor-receptor (EGF-R) signaling pathway by oral administration of the EGF-R tyrosine kinase inhibitor PKI166 can inhibit angiogenesis and growth of SN12PM6 human renal cell carcinoma (HRCC) in the kidney of nude mice and whether gemcitabine can potentiate these effects. In vitro treatment of HRCC cells with PKI166 inhibited EGF-R autophosphorylation, which correlated with a decrease in expression of Bcl-xl protein and phosphorylation of signal transducers and activators of transcription, particularly signal transducers and activators of transcription 3. PKI166 also decreased expression of vascular endothelial growth factor and basic fibroblast growth factor in a dose-dependent manner. Oral administration of PKI166 or PKI166 and injected gemcitabine or gemcitabine alone beginning 7 days after implantation of SN12PM6 cells into the kidney of athymic nude mice reduced the volume of tumors by 26, 61, and 23%, respectively. In another experiment 28 days after the orthotopic implantation of SN12PM6 cells, nephrectomy was performed followed by 4 weeks of treatment. Treatment with PKI166 and, more so, PKI166 plus gemcitabine significantly inhibited lung metastasis, corresponding to a significant increase in overall length of survival. EGF-R activation was significantly blocked by therapy with PKI166 and was associated with a significant reduction in expression of vascular endothelial growth factor and interleukin-8, decreased microvessel density, decreased staining of proliferating cell nuclear antigen, and increased tumor cell apoptosis. Collectively, the data indicate that targeting activation of EGF-R on HRCC produces significant therapeutic benefits.

Topics: Administration, Oral; Animals; Antineoplastic Agents; Apoptosis; Blotting, Western; Carcinoma, Renal Cell; Deoxycytidine; DNA-Binding Proteins; Down-Regulation; Endothelial Growth Factors; Enzyme Inhibitors; ErbB Receptors; Gemcitabine; Immunohistochemistry; In Situ Nick-End Labeling; Intercellular Signaling Peptides and Proteins; Kidney; Lung; Lymphokines; Mice; Mice, Nude; Neoplasm Metastasis; Neovascularization, Pathologic; Phosphorylation; Proliferating Cell Nuclear Antigen; Protein-Tyrosine Kinases; Pyrimidines; Pyrroles; Signal Transduction; STAT3 Transcription Factor; Time Factors; Trans-Activators; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

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