Evaluation of Near Infrared Dyes as Markers of P-Glycoprotein Activity in Tumors

Abstract

Aim: The multidrug resistance protein 1 (MDR1; P-glycoprotein) has been associated with efflux of chemotherapeutic agents from tumor cells and with poor patient prognosis. This study evaluated the feasibility of non-invasive, non-radioactive near infrared (NIR) imaging methodology for detection of MDR1 functional activity in tumors.Methods: Initial accumulation assays were conducted in MDR1-overexpressing MDCK cells (MDCK-MDR1) and control MDCK cells (MDCK-CT) using the NIR dyes indocyanine green (ICG), IR-783, IR-775, rhodamine 800, XenoLight DiR, and Genhance 750, at 0.4 μM–100 μM. ICG and IR-783 were also evaluated in HT-29 cells in which MDR1 overexpression was induced by colchicine (HT-29-MDR1) and their controls (HT-29-CT). In vivo optical imaging studies were conducted using immunodeficient mice bearing HT-29-CT and HT-29-MDR1 xenografts.Results: ICG’s emission intensity was 2.0- and 2.2-fold higher in control versus MDR1-overexpressing cells, in MDCK and HT-29 cell lines, respectively. The respective IR-783 control:MDR1 ratio was 1.4 in both MDCK and HT-29 cells. Optical imaging of mice bearing HT-29-CT and HT-29-MDR1 xenografts revealed a statistically non-significant, 1.7-fold difference (p > 0.05) in ICG emission intensity between control and MDR1 tumors. No such differences were observed with IR-783.Conclusion: ICG and IR-783 appear to be weak MDR1 substrates. In vivo, low sensitivity and high between-subject variability impair the ability to use the currently studied probes as markers of tumor MDR1 activity. The results suggest that, for future use of this technology, additional NIR probes should be screened as MDR1 substrates.

Apical Sodium-Dependent Bile Acid Cotransporter, A Novel Transporter of Indocyanine Green, and Its Application in Drug Screening

“…We chose other ASBT inhibitors (Nifedipine and cyclosporine A) and substrate (taurocholate and deoxycholate) for the validation. Nifedipine has been reported as an ASBT inhibitor; however, the ICG intensity increased on pretreatment with Nifedipine (Figure 7d,f), because Nifedipine is also an MDR1 inhibitor and the ICG efflux transporter [13,29]. The half maximal effective concentration (EC50) value of ICG for MDR1 is 15 ± 1.1 µM in Madin-Darby canine kidney (MDCK) cells with MDR1 overexpression [30].…”

“…Indocyanine green (ICG), a Food and Drug Administration (FDA) approved drug (dye) for liver function testing and tumor detection, is a near-infrared fluorophore with better penetration and lower autofluorescent background compared with traditional fluorescent proteins, such as green fluorescent protein (GFP) and red fluorescent protein [7][8][9][10][11]. The influx and efflux of ICG occur through NTCP and OATP1B3 and multidrug resistance p-glycoprotein 3 (MDR3) and multidrug resistance p-glycoprotein 1 (MDR1), respectively [12][13][14]. In our previous study, we demonstrated the use of NTCP and OATP1B3 as reporter genes combined with ICG for in vivo tumor cell tracking [15,16].…”

Use of photoimmunoconjugates to characterize ABCB1 in cancer cells

“…Fluorescent substrates of the transporter have been commonly used to image and assess its efflux function in pre-clinical settings. Indocyanine green (ICG) was the first FDA-approved dye used for fluorescence imaging of ABCB1 [ 5 , 6 ]. However, a statistically non-significant 1.7-fold difference in ICG fluorescence was observed between ABCB1-overexpressing tumors and normal tissues in mouse xenografts [ 6 ].…”

“…Indocyanine green (ICG) was the first FDA-approved dye used for fluorescence imaging of ABCB1 [ 5 , 6 ]. However, a statistically non-significant 1.7-fold difference in ICG fluorescence was observed between ABCB1-overexpressing tumors and normal tissues in mouse xenografts [ 6 ]. This suggests there is a need for enhanced fluorescence selectivity to label ABCB1 in diseased tissues.…”