The Effect Of Novel Alpha-Fetoprotein-Derived Peptide And Tamoxifen On Proliferation Of Cultured Human Glioblastoma Cells

Proc Amer Assoc Cancer Res, Volume 47, 2006 4741 INTRODUCTION: Glioblastoma multiforme (GBM) is the most frequent tumors of the central nervous system (CNS). Patients with a diagnosis of GBM have poor prognosis despite advances in cancer treatment and surgical techniques. Consequently, new therapeutic agents are in demand for management these patients. Recently, an anti-estrogen, tamoxifen, has been evaluated for the treatment of CNS tumors. At high doses, tamoxifen has some benefit for patients with glioblastomas. Here, the effect of a novel anti-estrogen, alpha-fetoprotein derived peptide, AFPep, on the inhibition of U87 human glioblastoma cell proliferation was evaluated and compared with activity of tamoxifen. METHODS: The U87 human glioblastoma cell line was obtained from ATCC. Cells were cultured as a monolayer in Modified Eagle’s Medium (MEM) with 10% fetal bovine serum, 15 mmol/L L-gutamine, 100 units/ml penicillin, and 100 mcg/ml streptomycin in a humidified 5% CO2 atmosphere at 37°C. Cells were released from monolayer by trypsinization using 0.25% trypsin in 0.25% EDTA. To examine the effect of AFPep and tamoxifen on U87 cell proliferation, cells were seeded into 6-well plastic tissue culture plates at a density of 1 x 105 cells/well in 4 ml of medium. Cultures were allowed to stabilize for 24 hours before being exposed to the various treatments. Various concentrations of AFPep and tamoxifen were added with medium changes every other day for 5 days. Cultures were then fixed with 10% acetic acid and stained with crystal violet solution. Unbound crystal violet was removed with multiple washes of the wells with tap water. Cell-bound rhodamine was extracted using acetic acid and measured by absorbance at 515 nm and plotted against drug concentration. Wells were set up in triplicate for each group. Mean absorbence + the standard error was calculated for each group. AFPep was synthesized using FMOC chemistry solid phase peptide synthesis on a Pioneer Peptide Synthesis System. RESULTS: The anti-cancer activity of AFPep was determined against cultured human glioblastoma cells U87. The results indicated that tamoxifen and AFpep showed significant inhibition of cultured human glioblastoma cells U87 (p < 0.05). Tamoxifen inhibits the proliferation in dose-dependent manner with IC50 of 10 mcM. AFPep also have dose-dependent inhibitory activity with the IC50 < 0.01 mcM. Studies to establish tamoxifen and combination studies to determine additive or synergistic effect are in progress. CONCLUSION: These data certainly showed that AFPep has significant inhibitory effect in the proliferation of cultured U87 human glioblastoma cells. Like tamoxifen, the inhibitory effect of AFPep is dose-dependent. Unlike tamoxifen, however, AFPep is a peptide derived from a natural product, alpha-fetoprotein. As such AFPep will be well tolerated and may be used to treat malignant glioblastomas with minimal or no adverse side effects.