ENHANCED p53-DEPENDENT GROWTH INHIBITION OF HUMAN GLIOBLASTOMA CELLS BY COMBINATORIAL TREATMENT OF TEMOZOLOMIDE AND NOVEL PURIFIED NATURAL CARBOHYDRATE OF PLEUROTUS FLORIDA

Objective: This study was designed to analyze the combinatorial chemotherapeutic effect of temozolomide (TMZ), the most common drug in glioblastoma treatment and a purified carbohydrate (Fr-II) from the edible mushroom Pleurotus florida, on human glioblastoma cell lines.Methods: Fr-II was purified by size-exclusion chromatography and characterised by different mass spectroscopy analysis. Human glioblastoma cells were treated with TMZ, Fr-II, and combination of TMZ and Fr-II. Cell cytotoxicity was measured by MTT assay, cell cycle phase distribution was determined by cell cycle analysis and followed by the relative p53 protein expression was analyzed by western blot analysis.Results: Chemical analysis of Fr-II confirmed the glycosidically linked two units of glucose with terminally attached mannitol with mass of 506 Da. Fr-II treatment exhibited cytotoxicity in both the cell lines in a dose-dependent manner with most effective dose at 200µg/ml. When Fr-II (200µg/ml) was combined with a dose range of TMZ it showed a more cellular cytotoxicity compared to the cytotoxicity of TMZ alone with most oppressive combinatorial dose at 400µM (TMZ)+200µg/ml (Fr-II). In compliance, with the above results, both cell lines showed a 10% increase in no. of cells (p<0.05) in G2/M phase indicating an arrest of cell cycle and increased p53 protein expression (p<0.05) at the combinatorial dose than TMZ alone at 400µM, but Fr-II alone didn't show any cell cycle arrest nor did it show increased p53 expression.Conclusion: Therefore it confirms that Fr-II synergizes with TMZ to significantly intensify its anti-proliferative properties, thereby emerging as an effective element for combinatorial treatment of glioblastoma