Abstract
BACKGROUND: Retroperitoneal sarcomas (RPS) exhibit a high locoregional recurrence rate after macroscopically complete surgical resection. Systemic therapies have limited efficacy and significant adverse effects. Sarcoma cell lines are susceptible to paclitaxel (PTX), a microtubule stabilizer, in 2-dimensional (2-D) monolayer cell culture, but resistant in animal models. When locally delivered via drug-eluting buttresses supratherapeutic concentrations are achieved and PTX becomes efficacious. Due to the limitations of 2-D culture, we establish an organotypic culture system to model the mechanisms by which supratherapeutic and prolonged exposure of PTX is effective. METHODS: Liposarcoma tumors (LP6) were established subcutaneously in NU/J mice. Tumors were harvested, sliced with a vibratome (250 µm thick), and cultured on permeable trans wells. RESULTS: Organotypic culture viability was maintained up to 7 days with greater than 50 % viability. Tumor slices were composed of 82 % ± 7 % human liposarcoma cells with the remainder being mouse stroma as determined by CD44 staining. Under 4-day exposure, IC(50) of PTX with organotypic culture shifted 7000 rightward as compared to 2-D culture. A subset of 17 genes was significantly differentially expressed as compared to untreated controls, while no genes were differentially expressed after 1 day of treatment. Gene set enrichment analysis demonstrated enrichment in apoptotic, extracellular matrix, cell motility, and cell cycle pathways. Caspase-8 activation occurred only at 10,000 ng/mL and 4-days of PTX or greater. CONCLUSION: This study reports a reproducible, clinically relevant organotypic culture liposarcoma model, which can serve as an intermediary between in vitro and in vivo studies.