Apoptosis mediated cytotoxicity of citrus obacunone in human pancreatic cancer cells

Obacunone is one of the oxygenated triterpenoids found in rutaceae family. It has been demonstrated for various biological activities including inhibition of cancer cells proliferation and tumor. The current study is an attempt to understand the mode of cytotoxicity of obacunone using cultured pancreatic cancer (MDA Panc-28) cells. Obacunone exhibited dose and time dependant inhibition of Panc-28 cells proliferation. This was also associated with phosphatidylserine translocation from inner surface of plasma membrane to outer surface in the treated cells, suggesting the involvement of apoptosis. Analysis of cells treated with 50 and 100 mu M of obacunone suggests activation of initiator caspase-9 and effector caspase-3, indicating involvement of caspases induced apoptosis. Obacunone upregulated expression of tumor suppressor protein p53, pro-apoptotic protein Bax and downregulated anti-apoptotic protein Bcl2. Furthermore, release of cytochrome-c into cytosol was observed in the cells treated with obacunone. It also resulted in down regulation of vital inflammatory mediators such as NF kappa B and Cox-2 suggesting the anti-inflammatory potential. For the first time, current study provides an evidence on activation of caspase dependant, cytochrome-c mediated intrinsic apoptosis and anti-inflammatory activity in Panc-28 cells by citrus obacunone. Induction of cytotoxicity and apoptosis was also confirmed by fluorescent tagged microscopic images of obacunone treated Panc-28 cells. Published by Elsevier Ltd.