Uncovering diffusive states of the yeast membrane protein, Pma1, and how labeling method can change diffusive behavior.

We present and analyze video-microscopy-based single-particle-tracking measurements of the budding yeast (Saccharomyces cerevisiae) membrane protein, Pma1, fluorescently labeled either by direct fusion to the switchable fluorescent protein, mEos3.2, or by a novel, light-touch, labeling scheme, in which a 5 amino acid tag is directly fused to the C-terminus of Pma1, which then binds mEos3.2.

Characterization of LY2228820 dimesylate, a potent and selective inhibitor of p38 MAPK with antitumor activity.

p38α mitogen-activated protein kinase (MAPK) is activated in cancer cells in response to environmental factors, oncogenic stress, radiation, and chemotherapy. p38α MAPK phosphorylates a number of substrates, including MAPKAP-K2 (MK2), and regulates the production of cytokines in the tumor microenvironment, such as TNF-α, interleukin-1β (IL-1β), IL-6, and CXCL8 (IL-8). p38α MAPK is highly expressed in human cancers and may play a role in tumor growth, invasion, metastasis, and drug resistance.

Human carboxylesterase-2 hydrolyzes the prodrug of gemcitabine (LY2334737) and confers prodrug sensitivity to cancer cells.

Purpose: The oral prodrug of gemcitabine LY2334737 is cleaved systemically to gemcitabine; the mechanism responsible for hydrolysis is unknown. LY2334737 cytotoxicity was tested in the NCI-60 panel; mining of microarray expression data identified carboxylesterase (CES) as a top hydrolase candidate. Studies examined whether CES is responsible for hydrolysis and whether cellular CES expression confers prodrug sensitivity.

Quantification of gemcitabine incorporation into human DNA by LC/MS/MS as a surrogate measure for target engagement.

In this study, we report a method for direct determination of gemcitabine incorporation into human DNA. Gemcitabine (dFdC), a structural analog of the nucleoside deoxycytidine (dC), derives its primary antitumor activity through interruption of DNA synthesis. Unlike other surrogate measures, DNA incorporation provides a mechanistic end point useful for dose optimization.

Evaluation of the binding of the tricyclic isoxazole photoaffinity label LY475776 to multidrug resistance associated protein 1 (MRP1) orthologs and several ATP- binding cassette (ABC) drug transporters.

Several of the ATP-binding cassette (ABC) transporters confer resistance to anticancer agents and/or antiviral agents when overexpressed in drug-sensitive cells. Recently a MRP1 (ABCC1) tricyclic isoxazole inhibitor, LY475776 was shown to be a glutathione-dependent photoaffinity label of human MRP1 and showed poor labeling of murine mrp1, an ortholog that does not confer anthracycline resistance. In the present study, the specificity of LY475776 was examined for its ability to modulate or photolabel orthologs of MRP1 and several other drug efflux transporters of the ABC transporter family.

Characterization and application of a vinblastine-selected CACO-2 cell line for evaluation of p-glycoprotein.

The role of the adenosine triphosphate-binding cassette (ABC) superfamily of membrane transporters is well documented in tumor cell multidrug resistance. More recently, growing evidence of their influence on oral bioavailability, drug excretion rates, and drug-drug interaction potential at the intestinal level has stimulated much investigation. Our laboratory is interested in evaluating the apical (AP) ABC transporter P-glycoprotein (Pgp [mdr-1]) for its role in xenobiotic efflux at the intestinal level.

Identification and characterization of the canine multidrug resistance-associated protein.

Human multidrug resistance protein 1 (MRP1) confers resistance to the Vinca alkaloids, the anthracyclines, and the epipodophyllotoxins. It is also capable of binding to and transporting the glutathione S-conjugate leukotriene C4 (LTC4) in isolated membrane vesicles. To explore species differences that exist between MRP orthologs, we cloned and characterized the mRNA encoding a canine ortholog of human MRP1-designated canine MRP1 (canMRP1).