The use of paracetamol cytotoxic metabolite as targeted therapy for cancer cells through selective glutathione depletion / Marwa Ezz Eldeen Mohammad Sayour ; Supervised Rania Mohsen Abdelsalam , Mohammed Farrag Elyamany , Raafat Abdelgawwad Elawady

Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Pharmacology and Toxicology

Paracetamol has proved its ability to induce different cytotoxic mechanisms on hepatoma cells (HepG2) through its metabolism into the cytotoxic metabolite N-acetyl-p-benzoquinoneimine (NAPQI). However, NAPQI is detoxified by conjugation with cellular glutathione (GSH). Therefore, once GSH is depleted, NAPQI stimulates a wide range of oxidative reactions that result in cell necrosis and/or apoptosis. In this study, buthionine sulfoximine (BSO), a selective GSH depleting agent, was used in both primary rat hepatocytes and HepG2 cell line prior to their treatment with paracetamol. The aim was to explore the cellular effects of therapeutic- or low-dose paracetamol treatment on hepatoma cells versus normal rat hepatocytes in the presence or absence of BSO. The debate was to find a new strategy that would selectively protect normal tissues and sensitize tumor cells all together by using BSO with paracetamol.HepG2 cell line and normal murine hepatocytes were treated with BSO 8 hours prior to paracetamol. The cytotoxic effect of parcetamol (1 to 2 mM) and/or BSO (1mM) was studied on both cell types via SRB cytotoxicty assay and the results were later confirmed and explained by flow cytometry. Results showed that both drugs either alone or in combination have cytotoxic effects on both cell types. These effects were dose, time and cell type-dependant. Paracetamol dose-tailoring is of great benefit to adjust the perfect dose that can sensitize HepG2 while protecting normal hepatocytes against the cytotoxic effect of paracetamol. Currently, these doses of paracetamol are 1.5 and 2 mM which caused a survival decline to 0.311 (31%) and 0.327 (33%) respectively in HepG2 while for normal hepatocytes, it is 2 mM that improved their survival to 0.831 (83%). Moreover, PGE2 has proved its role in the cytotoxic effect of paracetamol and/or BSO and this role depends on tissue type

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