Fu, Dan, Zhou, Jing, Zhu, Wenjing, Manley, Paul W., Wang, Yingqi, Wylie, Andrew, Hood, Tami and Xie, Xiaoliang Sunney (2014) Quantitative Hyperspectral Stimulated Raman Scattering (SRS) Imaging of Intracellular Tyrosine Kinase Inhibitor Drug Distribution in Living cells. Imaging the intracellular distribution of tyrosine kinase inhibitors in living cells with quantitative hyperspectral stimulated Raman scattering.

Abstract

ABL1 tyrosine-kinase inhibitors (TKI) are front-line therapy for chronic myelogenous leukemia (CML) and represent the best known examples of targeted cancer therapeutics. However, the dynamic uptake of low molecular weight TKIs into cells and their intracellular behavior is largely unknown due to the difficulty of observing non-fluorescent small molecules at subcellular resolution. SRS microscopy is a powerful label-free and non-invasive optical imaging technique for studying biological systems. Recent developments in multiplex and hyperspectral SRS imaging have significantly expanded the repertoire of molecules that can be directly imaged. Here we present the direct visualization of two TKI drugs – imatinib and nilotinib inside living cells using hyperspectral SRS imaging. We demonstrate that when cells are incubated with these drugs (20 µM), both accumulate in lysosomes with a concentration enrichment of over 1000-fold. The lysosomal trapping of these drugs results from their lysosomotropic properties. In addition, low solubility appears to contribute significantly to the surprisingly large accumulation of nilotinib. These effects may be alleviated by elevating the lysosome pH. We show that by co-administering chloroquine, an anti-malaria drug which is known to neutralize lysosome pH and inhibit autophagy, the trapping of imatinib was reduced by ten-fold. Our results suggest that chloroquine may increase the efficacy of TKIs based on its lysosomotropic activities besides the commonly accepted autophagy inhibition mechanism.

Item Type:	Article
Additional Information:	The cell proliferation assay and phospho-STAT5 assay are ongoing and the results and implications will be appended once they are done, to strengthen the hypothesis of autophagy-independent mechanism of chloroquine sensitization.
Keywords:	Raman spectroscopy, SRS hyperspectral imaging, Tyrosine kinase inhibitor, Lysosomotropism
Date Deposited:	13 Oct 2015 13:13
Last Modified:	13 Oct 2015 13:13
URI:	https://oak.novartis.com/id/eprint/10715