The multidrug resistance (MDR1) P-glycoprotein functions as a broad specificity efflux transporter of structurally diverse natural product and xenobiotic compounds. P-glycoprotein also is an important component of the functional blood-brain barrier. To enable further studies of function and modulation of MDR1 P-glycoprotein in vitro and in vivo, two novel phosphine technetium(III) complexes were designed and characterized: trans-[2,2'-(1, 2-ethanediyldiimino)bis(1, 5-methoxy-5-methyl-4-oxo-hexenyl)]bis[methylbis(3-methoxy-1- propyl)ph osphine]Tc(III) (Tc-Q58) and trans-[5,5'-(1,2-ethanediyl diimino)bis(2-ethoxy-2-methyl-3-oxo-4-pentenyl)]bis[dimethyl(3- methox y-1-propyl)phosphine)]Tc(III) (Tc-Q63). In human drug-sensitive KB 3-1 cells and multidrug-resistant KB 8-5 and 8-5-11 derivative cell lines, expressing nonimmunodetectable, low, and high levels of MDR1 P-glycoprotein, respectively, accumulation of Tc-Q58 and Tc-Q63 was inverse to expression of the transporter. Differences between drug-sensitive and multidrug-resistant cells, while detectable at picomolar concentrations of each radiopharmaceutical, were independent of tracer concentration. Ratios of tracer accumulation in KB 3-1 and 8-5 cells were 62.3 and 48.1 for Tc-Q58 and Tc-Q63, respectively. Cell contents of Tc-Q58 and Tc-Q63 were enhanced up to 60-fold in MDR cells by known modulators of MDR1 P-glycoprotein, while drugs not in the multidrug-resistant phenotype had no effect on their accumulation. In KB 8-5 cells, potency of modulators was GF120918 >> cyclosporin A > verapamil. Accumulation of Tc-Q58 and Tc-Q63 in Sf9 insect cells infected with a recombinant baculovirus containing human MDR1 P-glycoprotein was reduced in a GF120918-reversible manner (EC50

These results indicate that gallium(III) complex 6. is recognized by MDR1 Pgp as an avid transport substrate, thereby providing a useful scaffold to generate (68)Ga radiopharmaceuticals for molecular imaging of Pgp transport activity in tumors and tissues in vivo using PET.

Enhanced mitochondrial transmembrane potentials in tumor cells have been proposed to confer tumor-selective-targeting properties to modestly lipophilic monocationic compounds. To explore the potential cytotoxic activity of lipophilic cationic metallopharmaceuticals containing a highly flexible hexadentate N4O2 Schiff-base phenolic ligand, we first synthesized precursors H3Mabi (1) and H3DMabi (2) by condensation of an appropriate linear tetraamine with substituted salicylaldehydes. The desired N4O2 ligands, (ethylenediamine)-N,N'-bis[propyl[(2-hydroxy-3-methoxybenzyl)imino]] and (ethylenediamine)-N,N'-bis[propyl[2-hydroxy-4,6-dimethoxybenzyl)-imino]] (R-ENBPI), were obtained by cleavage of the imidazolidine ring, and their corresponding monocationic complexes were produced by reaction with appropriate hydrated salts or acetylacetonates of Al(III), Fe(III), Ga(III), and In(III). All complexes were stable to neutral hydrolysis. In human epidermal carcinoma KB-3-1 cells, cytotoxic potencies of racemic mixtures of these complexes were in the low micromolar range and, for a given ligand, depended on the identity of the coordinating central metal. The active 4,6-dimethoxy-ENBPI complexes were more potent than their 3-methoxy analogs, while the free ligands and metal(III) ions showed little or no cytotoxic activity. Furthermore, in colchicine-selected KB-8-5 multidrug resistant (MDR) cells, modest cellular expression of human MDR1 P-glycoprotein conferred protection from the cytotoxic activities of Al(III), Fe(III), and Ga(III) R-ENBPI complexes indicating that these complexes were recognized as transport substrates by the P-glycoprotein efflux transporter. However, the cytotoxic activities of the corresponding In(III) complexes, while among the lowest in potencies, were also not altered by expression of MDR1 P-glycoprotein. Thus, for the Group III elements, human cells were capable of distinguishing R-ENBPI complexes formed of the same ligands with different metals. Furthermore, selected R-ENBPI metal(III) complexes may be useful as novel anticancer metallopharmaceuticals.

The gene expression profile in response to dietary docosahexaenoic acid rich oil for 6 wk was analyzed in the livers of male Sprague-Dawley rats to identify genes whose expression was regulated by dietary modification and correlated with serum lipid changes. Such genes may represent targets for intervention into cardiovascular health using nutraceuticals. High density glass microarrays containing approximately 7800 cloned expressed sequences from rat were used to identify those genes that responded to dietary long chain (n-3) fatty acids. In general, dietary long chain (n-3) fatty acids exhibited statistically significant lipid-lowering effects similar to a pharmaceutical alternative, fenofibrate, but showed narrower effects on the transcription of most of the genes assayed. The transcription patterns confirmed that the expression of several key genes involved in cholesterol metabolism, fatty acid beta-oxidation and lipogenesis was affected. These analyses indicated that stearoyl-coenzyme A (Delta9) desaturase, a key enzyme involved in the regulation of triglyceride biosynthesis and secretion, is a potential target for nutritional intervention for hyperlipidemia and cardiovascular health. In addition these results suggested that regulation of the farnesoid X receptor may be a key nutritionally regulated mediator of serum lipid changes. A nutritional product concept based on a convenient dietary aid demonstrated comparable efficacy with less spurious gene regulation than a pharmaceutical alternative.

P-glycoprotein-mediated multidrug resistance has emerged as different laboratories. 8 Furthermore, there has been lack of one of the most attractive targets to improve anticancer theragreement on the optimal methodology for characterizing Papy. The P-glycoprotein functions as an energy-dependent, glycoprotein expression. The sensitivity of immunological membrane transport pump capable of decreasing the intrareagents appears to be a significant problem with low levels cellular concentration of a broad range of chemotherapeutic of P-glycoprotein expression. Analysis of extracted RNA has agents. Pharmaceuticals which inhibit P-glycoprotein transport activity are currently being evaluated in clinical trials. Characbeen hampered by the inclusion of tissue stroma which terization of P-glycoprotein functional activity is critical in includes capillaries and lymphocytes which may express high determining if these multidrug resistance reversal agents levels of endogenous P-glycoprotein.