sdz-psc-833 and Disease-Models--Animal

Paraquat is a herbicide that is highly toxic to the lungs and kidneys following acute exposures. Prior studies have demonstrated that the organic cation transporter 2 and multidrug and toxin extrusion protein 1 contribute to the urinary secretion of paraquat in the kidneys. The purpose of this study was to determine whether the multidrug resistance protein 1 (MDR1/Mdr1, ABCB1, or P-glycoprotein) also participates in the removal of paraquat from the kidneys and protects against renal injury. Paraquat transport and toxicity were quantified in human renal proximal tubule epithelial cells (RPTEC) that endogenously express MDR1, HEK293 cells overexpressing MDR1, and Mdr1a/1b knockout mice. In RPTEC cells, reduction of MDR1 activity using the antagonist PSC833 or siRNA transfection increased the cellular accumulation of paraquat by 50%. Reduced efflux of paraquat corresponded with enhanced cytotoxicity in PSC833-treated cells. Likewise, stable overexpression of the human MDR1 gene in HEK293 cells reduced intracellular levels of paraquat by 50%. In vivo studies assessed the renal accumulation and subsequent nephrotoxicity of paraquat (10 or 30 mg/kg ip) in wild-type and Mdr1a/1b knockout mice. At 4 h after paraquat treatment, renal concentrations of paraquat in the kidneys of Mdr1a/1b knockout mice were 750% higher than wild-type mice. By 72 h, paraquat-treated Mdr1a/1b knockout mice had more extensive tubular degeneration and significantly greater mRNA expression of kidney injury-responsive genes, including kidney injury molecule-1, lipocalin-2, and NAD(P)H quinone oxidoreductase 1, compared with wild-type mice. In conclusion, MDR1/Mdr1 participates in the elimination of paraquat from the kidneys and protects against subsequent toxicity.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B; ATP-Binding Cassette Sub-Family B Member 4; Cyclosporins; Disease Models, Animal; Gene Expression Regulation; HEK293 Cells; Herbicides; Humans; Kidney Diseases; Kidney Tubules, Proximal; Mice, Inbred C57BL; Mice, Knockout; Paraquat; Renal Elimination; RNA Interference; RNA, Messenger; Time Factors; Transfection

Anti-cancer drugs access solid tumors via blood vessels, and must penetrate tumor tissue to reach all cancer cells. Previous studies have demonstrated steep gradients of decreasing doxorubicin fluorescence with increasing distance from blood vessels, such that many tumor cells are not exposed to drug. Studies using multilayered cell cultures show that increased P-glycoprotein (PgP) is associated with better penetration of doxorubicin, while PgP inhibitors decrease drug penetration in tumor tissue. Here we evaluate the effect of PgP expression on doxorubicin distribution in vivo.. Mice bearing tumor sublines with either high or low expression of PgP were treated with doxorubicin, with or without pre-treatment with the PgP inhibitors verapamil or PSC 833. The distribution of doxorubicin in relation to tumor blood vessels was quantified using immunofluorescence.. Our results indicate greater uptake of doxorubicin by cells near blood vessels in wild type as compared to PgP-overexpressing tumors, and pre-treatment with verapamil or PSC 833 increased uptake in PgP-overexpressing tumors. However, there were steeper gradients of decreasing doxorubicin fluorescence in wild-type tumors compared to PgP overexpressing tumors, and treatment of PgP overexpressing tumors with PgP inhibitors led to steeper gradients and greater heterogeneity in the distribution of doxorubicin.. PgP inhibitors increase uptake of doxorubicin in cells close to blood vessels, have little effect on drug uptake into cells at intermediate distances, and might have a paradoxical effect to decrease doxorubicin uptake into distal cells. This effect probably contributes to the limited success of PgP inhibitors in clinical trials.

Topics: Animals; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Blood Vessels; Breast Neoplasms; Cell Line, Tumor; Cyclosporins; Disease Models, Animal; Doxorubicin; Drug Therapy, Combination; Female; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Verapamil

Osteoarthritis (OA) is characterized by cartilage erosion, proteolysis of aggrecan and collagen, and disturbed synthesis rates of aggrecan and hyaluronan by chondrocytes. The hypothesis is tested that hyaluronan overproduction contributes to aggrecan loss from osteoarthritic cartilage.. Human chondrocytes or bovine cartilage explants were incubated with interleukin 1beta (IL-1beta) to induce upregulation of hyaluronan and downregulation of aggrecan. OA was induced by injection of iodoacetate into the synovial cavity in rat knees. Hyaluronan export was inhibited by ATP-binding cassette transporter inhibitors such as the multidrug resistance (MDR) inhibitors valspodar or verapamil. The concentration of aggrecan was measured in cell culture media or visualized histochemically in cartilage tissue sections.. Valspodar inhibited hyaluronan export from human chondrocytes in cell culture selectively without reducing aggrecan secretion. Valspodar and other MDR inhibitors prevented loss of aggrecan from osteoarthritic cartilage explants in culture. Verapamil prevented loss of aggrecan from cartilage in osteoarthritic rat knees.. Hyaluronan is synthesized at plasma membranes and exported out of the cell. We recently identified an ATP-binding cassette transport system that is responsible for hyaluronan export. A number of ATP-binding cassette transport inhibitors are known and are in use clinically. These inhibitors were used here to inhibit hyaluronan export and to prevent aggrecan loss from arthritic cartilage. New drugs for treatment of arthritis are suggested by these studies.

Topics: Aggrecans; Animals; Cartilage, Articular; Cattle; Cell Line; Chondrocytes; Cyclosporins; Disease Models, Animal; Dose-Response Relationship, Drug; Extracellular Matrix Proteins; Hindlimb; Humans; Hyaluronic Acid; Interleukin-1; Joints; Lectins, C-Type; Male; Osteoarthritis; Proteoglycans; Rats; Rats, Wistar

To determine the resistance reversion of mitomycin (MMC) by 3'-Keto-bmt1-val2-cyclosporin (SDZ PSC 833) in human cervical cancer in vitro and in vivo. METHEDS: A xenografted mitomycin resistant mice model of cervical cancer was devolped. The reversion of mitomycin resistance by SDZ PSC 833 (1 or 3 mg/L) was detected from human cervical cancer cell (Hela) and its resistant subline Hela/MMC in vitro and in vivo. Studies in vitro include drug resistance reversion experiment and the changes of morphology. Studies in vivo including tumor volume and tumor related histopathological changes in the autopsied specimen were evaluated by comparing random sections of each group.. Nontoxic doses of SDZ PSC 833 could result in almost partial reversion of MMC-resistance of Hela/MMC. In vivo studies also showed SDZ PSC 833 augmented the growth inhibitory effect of mitomycin on Hela/MMC xenografted in nude mice.. SDZ PSC 833 can overcome mitomycin resistance of Hela/MMC in vitro and in vivo, so SDZ PSC 833 will be a better candidate clinically for reversing multidrug resistance.

Topics: Animals; Antibiotics, Antineoplastic; Cyclosporins; Disease Models, Animal; Drug Resistance, Neoplasm; Female; HeLa Cells; Humans; Mice; Mice, Nude; Mitomycin; Uterine Cervical Neoplasms