MRI reveals the in vivo cellular and vascular response to BEZ235 in ovarian cancer xenografts with different PI3-kinase pathway activity.

BACKGROUND: The phosphoinositide-3 kinase (PI3K) pathway is an attractive therapeutic target. However, difficulty in predicting therapeutic response limits the clinical implementation of PI3K inhibitors. This study evaluates the utility of clinically relevant magnetic resonance imaging (MRI) biomarkers for noninvasively assessing the in vivo response to the dual PI3K/mTOR inhibitor BEZ235 in two ovarian cancer models with differential PI3K pathway activity. METHODS: The PI3K signalling activity of TOV-21G and TOV-112D human ovarian cancer cells was investigated in vitro. Cellular and vascular response of the xenografts to BEZ235 treatment (65 mg kg(-1), 3 days) was assessed in vivo using diffusion-weighted (DW) and dynamic contrast-enhanced (DCE)-MRI. Micro-computed tomography was performed to investigate changes in vascular morphology. RESULTS: The TOV-21G cells showed higher PI3K signalling activity than TOV-112D cells in vitro and in vivo. Treated TOV-21G xenografts decreased in volume and DW-MRI revealed an increased water diffusivity that was not found in TOV-112D xenografts. Treatment-induced improvement in vascular functionality was detected with DCE-MRI in both models. Changes in vascular morphology were not found. CONCLUSIONS: Our results suggest that DW- and DCE-MRI can detect cellular and vascular response to PI3K/mTOR inhibition in vivo. However, only DW-MRI could discriminate between a strong and weak response to BEZ235.

Microemulsion electrokinetic chromatography in suppressed electroosmotic flow environment. Separation of fat-soluble vitamins.

Microemulsion electrokinetic chromatography (MEEKC) was carried out in a pH 2.5 phosphate buffer to effectively suppress the electroosmotic flow (EOF). With 66.6% (w/w) 25 mM phosphate buffer pH 2.5, 20.0% (w/w) 2-propanol, 6.6% (w/w) 1-butanol, 6.0% (w/w) sodium lauryl sulphate (SDS), and 0.8% (w/w) n-octane as the separation medium, the fat-soluble vitamins A palmitate, E acetate, and D3 were baseline separated within 11 min. With strongly suppressed EOF, the polarity of the separation voltage was reversed (positive electrode at the outlet); the n-octane micro droplets surrounded by negatively charged SDS molecules migrated towards the detector. The aqueous part of the microemulsion was modified with 20% (w/w) 2-propanol to improve partition between the n-octane phase and the surrounding aqueous medium. The fat-soluble vitamins were separated in order of decreasing hydrophobicity with a high migration time stability (repeatable within 0.1% RSD). Excellent accuracy and precision were obtained when the system was applied for the determination of vitamin E acetate in commercial vitamin tablets; quantitative data corresponded to 97.0% of label claim, intra-day results varied within 1.72% RSD (n=6), and inter-day results varied within 3.22% RSD (n=5).