Mechanism Determination of the Effects of Pancratistatin on Model Mitochondrial Membranes
Apoptosis is programmed cell death that is essential for physiological development and tissue homeostasis. From a biochemical standpoint, this process can be exploited to target and eliminate specific cell types, such as cancer cells. Pancratistatin (PST) is an antiviral alkaloid metabolite that has demonstrated directed apoptotic action on various human cancer cell lines while having minimal/no toxic effect on normal cells. However, PST’s mechanism of action remains uncertain. To better understand how PST induces its anti-cancer action various biophysical techniques were employed. Neutron spin-echo (NSE) spectroscopy was used to examine how PST impacted the bending fluctuations of large unil- amellar vesicles (LUVs) bearing a lipid composition meant to mimic the inner mitochondrial membranes (IMM). The IMM mimic was composed of three lipids: 1-palmitoyl-2-oleoyl-sn- glycero-3-phosphocholine (POPC), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), and tetraoleoyl cardiolipin (TOCL). Small-angle neutron and X-ray scattering (SANS and SAXS) were utilized to determine how PST influences membranes structure. Molecular dynamics (MD) simulations were used to compliment the data gathered from the scattering experiments, while also examining lipid chain order, PST localization and the PST-lipid relationships. The results show that PST has a condensing effect the IMM mimic. This thesis elaborates on the possible implications of this finding with regard to the nature of PST’s interaction with the IMM mimic and proposes a hypothesis for the anti-cancer mechanism of PST.
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