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In order to investigate the antitumor and antimetastatic efficacy of new chemotherapeutic agents, a novel, red-fluorescent, orthotopic model of pancreatic cancer was constructed in nude mice. MIA-PaCa-2 human pancreatic cancer cells were transduced with red fluorescent protein (RFP) and initially grown subcutaneously. Fluorescent tumor fragments were then transplanted onto the pancreas by surgical orthotopic implantation (SOI), facilitating high-resolution, real-time visualization of tumor and metastatic growth and dissemination in vivo. Tumor growth at the primary site was visible within the first postoperative week, while distant metastasis and the development of ascites became visible over the following week. This MIA-PaCa-2-RFP model produced extensive local disease and metastases to the retroperitoneum (100%), spleen (100%), intestinal and periportal lymph nodes (100%), liver (40%) and diaphragm (80%), and gave rise to malignant ascites and peritoneal carcinomatosis in 80% of cases. Growth and metastasis of tumor was more rapid and frequent than in previously described orthotopic pancreatic cancer models, leading to a median survival of only 21 days after tumor implantation. This unique, red fluorescent model rapidly and reliably simulates the highly aggressive course of human pancreatic cancer and can be easily non-invasively visualized in the live animal. The model can therefore be used for the discovery and evaluation of novel therapeutics for the treatment of this devastating disease.

Background: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in malignant cells but not in normal cells. Ad/g-TRAIL, an adenoviral vector in which expression of green fluorescent protein (GFP) and TRAIL is driven by a human telomerase reverse transcriptase promoter, has shown promise as a targeted antitumor agent.Methods: To investigate the effects of TRAIL gene therapy on pancreatic cancer, BxPC-3, MIA-PaCa-2, Panc-1, and ASPC-1 cells were treated with Ad/g-TRAIL. Transfection and protein expression were determined by using immunoblotting and identification of GFP with fluorescent microscopy and flow cytometry. Cell viability was determined by proliferation assay. Cell-cycle analysis and quantification of caspase-3 were used to identify apoptosis. The in vivo efficacy of Ad/g-TRAIL was characterized in a novel red fluorescent protein murine model of MIA-PaCa-2 pancreatic cancer.Results: Cells treated with Ad/g-TRAIL expressed GFP and exhibited apoptotic morphology within 2 days of treatment. Treatment with this vector in vitro resulted in less cell viability, increased caspase-3 activity, and a greater apoptotic fraction than treatment with controls. In vivo, treatment with Ad/g-TRAIL significantly suppressed tumor growth.Conclusions: TRAIL gene therapy induces apoptosis of pancreatic tumor cells both in vitro and in vivo and is a promising therapy in the treatment of pancreatic cancer.

Adjuvant treatment with the cytosine analogue 1-(2-C-cyano-2-deoxy-␤-D-arabino-pentofuranosyl)-N 4 -palmitoylcytosine (CS-682) results in a highly significant increase in survival in the aggressive orthotopic MIAPaCa-2 human pancreatic cancer mouse model. Seven days after implantation, mice were randomized into eight groups, depending on whether they were to be treated by tumor resection, 5 weeks of CS-682 chemotherapy at 40 -60 mg/kg once daily, or both. Throughout the course of treatment, noninvasive optical whole-body imaging based on brilliant red fluorescent protein expression of the tumor permitted visualization and quantification of primary, metastatic, and recurrent disease. Total tumor burden negatively correlated with survival. Untreated mice died of disseminated disease with a median survival of 26 days. Surgical resection alone conferred a small but significant survival advantage (median survival, 28 days, P ‫؍‬ 0.03). Primary CS-682 treatment at all doses also significantly prolonged survival compared with untreated animals (P < 0.05) and was more effective than surgery alone at doses of 50 and 60 mg/kg (median survival, 34 days, P ‫؍‬ 0.045, and 38.5 days, P ‫؍‬ 0.03, respectively). Maximal survival (median, 48 days, with 30% of animals surviving longer than 60 days) was achieved by adjuvant CS-682 (50 mg/kg), given after surgical resection of the primary pancreatic tumor (P ‫؍‬ 0.004 compared with surgery alone). The results demonstrate that adjuvant oral administration of CS-682 for pancreatic cancer is highly effective with acceptable toxicity, suggesting its potential for cure of this disease in appropriate combinations.

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