Evaluating the Anti-Proliferative Effects of Less Toxic Agents Against High-Risk Neuroblastoma Cells

Neuroblastoma (NB) is the most common extracranial pediatric cancer. High Risk Neuroblastoma (HRNB) is aggressive with a 40-50% 5-year survival rate (5YSR). Racial and ethnic disparities in NB patients demonstrated 5YSR is lower in African American and Native American children. Our laboratory is testing combination treatments using less toxic agents to induce HRNB sensitization to chemotherapy. Non-Steroidal Anti-Inflammatory Drug, tolfenamic acid (TA) inhibits Specificity protein 1 (Sp1) and survivin, markers associated with resistance to chemo/radiation therapies. The objective is to identify agents more effective than TA for combination treatments. The hypothesis is as follows: two derivatives of TA will have more efficient anti-proliferative effects on HRNB cells. Anti-proliferative activity of derivatives on HRNB cell lines (LA-155n and SMS-KCNR) and non-malignant (cardiomyocytes) cells was evaluated. Methods include treating cells with TA and TA derivatives (TA-D1 and TA-D2) in increasing concentrations (0, 5, 10, 20, 40, and 80 µM) for 48 hours, measuring viable cells using CellTiterGlo kit, generating dose curves and determining the dose required to inhibit 50% of cell growth (IC50 value) using Sigma-Plot software. TA-D1 (IC50 = 29 µM) and TA-D2 (IC50 = 3 µM) had lower IC50 values than TA (IC50 = 75 µM). TA and its derivatives had no effect on cardiomyocytes. Western blot results showed decreased expression of Sp1 and survivin in HRNB cells treated with TA-D1. In conclusion, TA derivatives may effectively sensitize certain HRNB cells and induce chemo/radiation therapy response. Further studies to understand mechanisms of these derivatives and safety against non-malignant cells are underway