Metalloprobes: Fluorescence imaging of multidrug resistance (MDR1) P-Glycoprotein (Pgp)-mediated functional transport activity in cellulo

67Ga-metalloprobes: monitoring the impact of geometrical isomers on accumulation profiles in rat cardiomyoblasts and human breast carcinoma cells

“…Recently, we have reported preclinical validation of Galmydar, a PET tracer incorporated with a generator produced radionuclide gallium-68, and demonstrated its potential for imaging myocardial perfusion 3 and functional expression of the ABC family of transporters. 15 Others [16][17][18] and we have also demonstrated that the presence of an overall cationic charge on metalloprobes mediates their localization within the mitochondria of penetrated cells 19,20 and pharmacokinetic profiles in vivo. 13,14 However, the relationship between the spatial distribution of charges on their molecular surface resulting from preferential geometry including different geometrical isomers and their overall impact upon penetration of metalloprobes into myocardium and tumor cells has not been ascertained.…”

Live-cell fluorescence imaging: assessment of thioflavin T uptake in human epidermal carcinoma cells

“…1) could also be employed to monitor its ability to interact with the ABC family of transporters, such as Pgp, and track its intracellular localization using live cell imaging. Earlier, we have shown that this technique can be successfully employed to assess the functional expression of the ABC family of transporters, such as Pgp 19 and BCRP. 18 Therefore, the cellular accumulation of ThT, a cationic molecule, as a function of its concentration was assessed in human epidermal carcinoma cells to determine the optimal concentration of the probe needed for live cell imaging.…”

“…Previously, others 22 and our laboratory have shown that hydrophobic and monocationic metalloprobes also penetrate non-MDR cells in response to favorable negative transmembrane potential gradients, existing at the plasma membrane and across mitochondrial membranes to localize within the mitochondria. 16,17,19,20,29,30 To directly evaluate intracellular localization, ThT was also incubated in non-MDR cells in either the presence or absence of MitoTracker® (Mito-thioflavin T (ThT) Mitotracker Red Merge Tracker® Red CMH 2 XRos), a well-known fluorescent marker for staining mitochondria. ThT penetrated KB-3-1 cells, demonstrating a close correlation with the MitoTracker Red (Fig.…”

“…Human epidermal carcinoma colchicine-derived MDR KB-8-5 cells (Pgp+) were grown in media supplemented with colchicine (25 nM). [19][20][21] Cell transport studies and live cell fluorescence imaging Evaluation of cellular accumulation of thioflavin T (ThT) and PiB in human epidermal carcinoma cells using live cell fluorescence imaging. For evaluation of cellular transport assays via microscopy, human epidermal carcinoma KB-3-1 (non-MDR, Pgp−) and KB-8-5 (MDR, Pgp+) cells were plated onto borosilicate 8-well chambered (25 000 cells per well) slides (Nalge Nunc International, Rochester, NY) and allowed to grow to approximately 70% confluence at 37°C under a 5% CO 2 atmosphere.…”

“…14,15 Within the specific context of delivery of drugs and imaging probes, across the blood-brain barrier (BBB), among various biochemical pathways controlling the delivery of molecules into the brain, P-glycoprotein (Pgp, ABCB1) and BCRP (breast cancer resistance protein, BCRP, ABCG2), the well-characterized members of the ABC family of transporters, are recognized as prominent drug transporter proteins lining the luminal surface of brain endothelial cells. These transporter proteins also play a vital role in regulating normal physiological functions, [16][17][18][19] while also limiting the delivery of their recognized substrates across the blood-brain barrier. Previously, others and our laboratory have shown that Pgp (ABCB1)-recognized substrates possess nitrogen atoms in their scaffolds that can be protonated under physiological conditions and are also moderately hydrophobic.…”