Canine MDR1 gene mutations produce translated P-glycoprotein, an active drug efflux transporter, resulting in dysfunction or over-expression. The 4-base deletion at exon 4 of MDR1 at nucleotide position 230 (nt230[del4]) in exon 4 makes P-glycoprotein lose function, leading to drug accumulation and toxicity. The G allele of the c.-6-180T>G variation in intron 1 of MDR1 (single nucleotide polymorphism [SNP] 180) causes P-glycoprotein over-expression, making epileptic dogs resistant to phenobarbital treatment. Both of these mutations are reported to be common in collies. This study develops a more efficient method to detect these two mutations simultaneously, and clarifies the genotype association with the side effects of chemotherapy. Genotype distribution in Taiwan was also investigated. An oligonucleotide microarray was successfully developed for the detection of both genotypes and was applied to clinical samples. No 4-base deletion mutant allele was detected in dogs in Taiwan. However, the G allele variation of SNP 180 was spread across all dog breeds, not only in collies. The chemotherapy adverse effect percentages of the SNP 180 T/T, T/G, and G/G genotypes were 16.7%, 6.3%, and 0%, respectively. This study describes an efficient way for MDR1 gene mutation detection, clarifying genotype distribution, and the association with chemotherapy.
Alleles ; Animals ; Dogs ; Drug Therapy ; Exons ; Genotype ; Introns ; Methods ; Oligonucleotide Array Sequence Analysis ; P-Glycoprotein ; Phenobarbital ; Taiwan

BACKGROUND: P-glycoprotein (P-gp) transports many chemicals that vary greatly in their structure and function. It is normally expressed in renal proximal tubular cells. We hypothesized that P-gp expression influences light chain excretion. Therefore, we investigated whether renal tubular P-gp expression is altered in patients with plasma cell disorders. METHODS: We evaluated renal biopsy specimens from patients with plasma cell disorders (n = 16) and primary focal segmental glomerulosclerosis (the control group, n = 17). Biopsies were stained with an anti-P-gp antibody. Loss of P-gp expression was determined semi-quantitatively. Groups were compared for loss of P-gp expression, and clinical variables. RESULTS: P-gp expression loss was more severe in patients with plasma cell disorders than it was in those with glomerulonephritis (P = 0.021). In contrast, clinical and histological parameters including serum creatinine, level of urinary protein excretion, and interstitial fibrosis/tubular atrophy grade were not significantly different between the groups. P-gp expression loss increased with age in patients with plasma cell disorders (P = 0.071). This expression loss was not associated with serum creatinine, the level of urinary protein excretion or the interstitial fibrosis/tubular atrophy grade. There was no significant association between the severity of P-gp expression loss with the types and serum levels of light chains, isotypes and serum immunoglobulin levels. CONCLUSION: Renal tubular P-gp expression is significantly down-regulated in patients with plasma cell disorders characterized by nephrotic range proteinuria. Additional studies are needed to determine whether reintroduction of renal tubular P-gp expression would mitigate the proximal tubular injury that is caused by free-light chains.
Amyloidosis ; Atrophy ; Biopsy ; Creatinine ; Glomerulonephritis ; Glomerulosclerosis, Focal Segmental ; Humans ; Immunoglobulin Light Chains ; Immunoglobulins ; P-Glycoprotein ; Plasma Cells ; Plasma ; Proteinuria

PURPOSE: The DNA damage response (DDR) is a multi-complex network of signaling pathways involved in DNA damage repair, cell cycle checkpoints, and apoptosis. In the case of biliary tract cancer (BTC), the strategy of DDR targeting has not been evaluated, even though many patients have DNA repair pathway alterations. The purpose of this study was to test the DDR-targeting strategy in BTC using an ataxia-telangiectasia and Rad3-related (ATR) inhibitor. MATERIALS AND METHODS: A total of nine human BTC cell lines were used for evaluating anti-tumor effect of AZD6738 (ATR inhibitor) alone or combination with cytotoxic chemotherapeutic agents through MTT assay, colony-forming assays, cell cycle analyses, and comet assays. We established SNU478-mouse model for in vivo experiments to confirm our findings. RESULTS: Among nine human BTC cell lines, SNU478 and SNU869 were the most sensitive to AZD6738, and showed low expression of both ataxia-telangiectasia mutated (ATM) and p53. AZD6738 blocked p-Chk1 and p-glycoprotein and increased γH2AX, a marker of DNA damage, in sensitive cells. AZD6738 significantly increased apoptosis, G2/M arrest and p21, and decreased CDC2. Combinations of AZD6738 and cytotoxic chemotherapeutic agents exerted synergistic effects in colony-forming assays, cell cycle analyses, and comet assays. In our mouse models, AZD6738 monotherapy decreased tumor growth and the combination with cisplatin showed more potent effects on growth inhibition, decreased Ki-67, and increased terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling than monotherapy with each drug. CONCLUSION: In BTC, DDR targeting strategy using ATR inhibitor demonstrated promising antitumor activity alone or in combination with cytotoxic chemotherapeutic agents. This supports further clinical development of DDR targeting strategy in BTC.
Animals ; Apoptosis ; Ataxia Telangiectasia ; Biliary Tract Neoplasms ; Biliary Tract ; Cell Cycle ; Cell Cycle Checkpoints ; Cell Line ; Cisplatin ; Comet Assay ; DNA Damage ; DNA Repair ; DNA ; Humans ; Mice ; P-Glycoprotein

Paclitaxel (PTX) is one of the most frequently used anticancer agent for treating refractory ovarian cancer, metastatic breast cancer and non-small cell lung cancer. However, its oral administration is impeded by very low bioavailability (<5%) due to the P-glycopprotein (P-gp) efflux pump effect. This study investigated in vitro and in vivo P-gp inhibitory effects of adamantyl derivatives AC-603 and AC-786 in rats. Two adamantyl derivatives tested in this study increased the cytotoxicity of daunomycin (DNM) in P-gp overexpressed cell line by inhibiting P-gp efflux function. Pharmacokinetics of PTX with orally co-administered P-gp inhibitors were assessed in rats to improve PTX absorption. The pharmacokinetic parameters of PTX were determined in rats after intravenous (2 mg/kg) or oral (25 mg/kg) administration in the presence or absence of verapamil (a positive control), AC-603 or AC-786 (0.5 mg/kg or 5 mg/kg). Compared to control group (PTX alone), experimental groups (PTX with AC-603 or AC-786) significantly increased the area under the plasma concentration-time curve of PTX following oral administration by 1.7–2.2 fold. The volume of distribution and total clearance of PTX were decreased, while other parameters were not significantly changed. In conclusion, co-administration of AC-603 or AC-786 enhanced the relative bioavailability of orally administered PTX as compared to control.
Absorption ; Administration, Oral ; Animals ; Biological Availability ; Breast Neoplasms ; Carcinoma, Non-Small-Cell Lung ; Cell Line ; Daunorubicin ; In Vitro Techniques ; Ovarian Neoplasms ; P-Glycoprotein ; Paclitaxel* ; Pharmacokinetics ; Plasma ; Rats* ; Verapamil

Oseltamivir is a substrate of P-glycoprotein, an efflux drug transporter encoded by ABCB1. The objective of this study was to assess the role of ABCB1 (c.1236C>T, c.2677G>T/A, and c.3435C>T) polymorphisms in the pharmacokinetics of oseltamivir and its active metabolite, oseltamivir carboxylate in humans. Nineteen healthy male subjects were enrolled, and their ABCB1 polymorphisms were evaluated. After the oral administration of 75 mg oseltamivir, the plasma concentrations of oseltamivir and oseltamivir carboxylate were measured. Pharmacokinetic analysis was carried out. Systemic exposure to oseltamivir and oseltamivir carboxylate was higher in the mutant group than in the wild-type and heterozygous groups. We suggest that ABCB1 polymorphisms affect the pharmacokinetics of oseltamivir in humans. Further studies in a large population are necessary to validate the results of this preliminary study (Clinical Trial Registration Information [CRIS] registry: http://cris.nih.go.kr, No. KCT0001903).
Administration, Oral ; Humans* ; Male ; Oseltamivir* ; P-Glycoprotein ; Pharmacokinetics* ; Plasma

<p><b>OBJECTIVEb>To predict and identify the target gene of miR-145, and to explore the underlying mechanism of the inhibition of miR-145 on drug resistance to Oxaliplatin (L-OHP) in human colorectal cancer cells.p><p><b>METHODSb>L-OHP-resistant human colorectal cancer cell line (HCT116/L-OHP) was established in vitro by exposing to increased concentrations of L-OHP in cell culture medium. MiR-145-mimics and its negative control (NC-miRNA) were transfected into HCT116/L-OHP cells using liposome to establish HCT116/L-OHPover-expressing miR-145 and HCT116/L-OHP. The target genes of miR-145 were predicted by bioinformatic analysis, and validated by dual luciferase activity assay. After determination of G protein coupled receptor 98(GPR98) as target gene, corresponding plasmids were constructed and transfected to establish HCT116/L-OHPover-expressing GPR98 and HCT116/L-OHP. HCT116/L-OHP cells over-expressing both GPR98 and miR-145 (HCT116/L-OHP) were acquired through modification of the binding sites of GPR98 cDNA with miR-145. CCK-8 assay was used to assess the proliferation (A value) and sensitivity to L-OHP (the lower the IC50, the stronger the sensitivity) in HCT116/L-OHP cells. Real-time quantitative PCR was used to measure the mRNA expression of miR-145 and GPR98. Western blot was used to examine the protein expression of GPR98 and drug-resistant associated protein, such as P-glycoprotein (gp), multiple drug-resistance protein 1(MRP1), cancer-inhibition gene PTEN.p><p><b>RESULTSb>HCT116/L-OHP cell line was successfully established with ICof (42.34±1.05) mg/L and miR-145 mRNA expression of 0.27±0.04, which was higher than (9.81±0.95) mg/L (t=39.784, P=0.000) and lower than 1.00±0.09 (t=13.021, P=0.000) in HCT116 cells. Based on HCT116/L-OHP cells, HCT116/L-OHPcells were established successfully, with relative miR-145 expression of 10.01±1.05, which was higher than 1.06±0.14 in HCT116/L-OHPand 1.00±0.16 in HCT116/L-OHP (F=161.797, P=0.000). GPR98 was identified to be the target gene of miR-145. The relative mRNA and protein expressions of GPR98 in HCT116/L-OHPcells were 8.48±0.46 and 1.71±0.09, respectively, which were higher than those in HCT116/L-OHP(mRNA: 3.65±0.40, protein: 1.21±0.10) and HCT116/L-OHP (mRNA: 3.49±0.35, protein: 1.22±0.08; all P<0.05). The A value was 1.31±0.10, and the relative protein expressions of P-gp and MRP1 were 1.53±0.18 and 1.49±0.20 in HCT116/L-OHPcells, which were higher than those in HCT116/L-OHP (A value: 0.82±0.08, relative protein expression: 1.00±0.06 and 1.21±0.13, all P<0.05). The A value was 0.89±0.08, and the relative protein expressions of P-gp and MRP were 1.02±0.24 and 1.38±0.25 in HCT116/L-OHPcells, which were higher than those in HCT116/L-OHP(A value: 0.20±0.05, relative protein expression: 0.20±0.07, 0.55±0.10, all P<0.05). The relative protein expression of PTEN in HCT116/L-OHPcells was 0.12±0.03, which was lower than 1.25±0.14 in HCT116/L-OHP cells(P<0.05). In addition, relative protein expressions of P-gp and MRP1 were 1.02±0.24 and 1.38±0.25 in HCT116/L-OHPcells, which were higher than those in HCT116/L-OHPcells (0.20±0.07 and 0.55±0.10), while PTEN expression in HCT116/L-OHPcells was lower as compared to HCT116/L-OHPcells (1.41±0.16 vs. 1.98±0.13, P<0.05).p><p><b>CONCLUSIONb>MiR-145 inhibits drug resistance to L-OHP of HCT116 cells through suppressing the expression of target gene GPR98.p>
ATP Binding Cassette Transporter, Sub-Family B ; drug effects ; ATP-Binding Cassette, Sub-Family B, Member 1 ; drug effects ; Cell Line, Tumor ; drug effects ; physiology ; Colorectal Neoplasms ; physiopathology ; Down-Regulation ; drug effects ; genetics ; Drug Resistance, Neoplasm ; drug effects ; genetics ; physiology ; HCT116 Cells ; drug effects ; physiology ; Humans ; In Vitro Techniques ; MicroRNAs ; genetics ; pharmacology ; Multidrug Resistance-Associated Proteins ; drug effects ; Organoplatinum Compounds ; pharmacology ; PTEN Phosphohydrolase ; drug effects ; RNA, Messenger ; Receptors, G-Protein-Coupled ; drug effects ; genetics

The aim of the present study was to develop three-dimensional (3D) culture model, a more pathologically relevant model, of human breast cancer for drug resistance study. MCF-7 cells were embedded within collagen gel to establish 3D culture model. Cellular morphology was observed using Carmine and HE staining. Cell proliferation was evaluated by CCK-8 assay, and cell activity was detected by Live/Dead staining kit. Drug sensitivities of the 3D culture to doxorubicin, carboplatin, 5-fluorouracil were assayed and compared with those of monolayer (2D) culture. In addition, the levels of drug resistance-related genes P-glycoprotein (P-gp), mrp2 mRNA expressions were detected by real time RT-PCR. Expression level of P-gp protein was detected by Western blot. The results showed that MCF-7 cells in 3D culture formed a number of cell aggregates, and most of them displayed good cell viability. The IC50 values of doxorubicin, carboplatin, 5-fluorouracil were all increased significantly in 3D culture compared with those in 2D culture. Moreover, compared with MCF-7 cells in 2D culture, the cells in 3D culture showed increased mRNA levels of P-gp and mrp2, as well as up-regulated protein expression of P-gp. These results suggest that in vitro collagen-embedded culture system of human breast cancer cells represents an improved pathologically relevant 3D microenvironment for breast cancer cells, providing a robust tool to explore the mechanism of drug resistance of cancer cells.
ATP-Binding Cassette, Sub-Family B, Member 1 ; Breast Neoplasms ; Cell Culture Techniques ; Cell Proliferation ; Cell Survival ; Doxorubicin ; Drug Resistance, Neoplasm ; Humans ; MCF-7 Cells

This study aimed to investigate the in vivo relevance of P-glycoprotein (P-gp) in the pharmacokinetics and adverse effect of phenformin. To investigate the involvement of P-gp in the transport of phenformin, a bi-directional transport of phenformin was carried out in LLC-PK1 cells overexpressing P-gp, LLC-PK1-Pgp. Basal to apical transport of phenformin was 3.9-fold greater than apical to basal transport and became saturated with increasing phenformin concentration (2-75 µM) in LLC-PK1-Pgp, suggesting the involvement of P-gp in phenformin transport. Intrinsic clearance mediated by P-gp was 1.9 µL/min while passive diffusion clearance was 0.31 µL/min. Thus, P-gp contributed more to phenformin transport than passive diffusion. To investigate the contribution of P-gp on the pharmacokinetics and adverse effect of phenformin, the effects of verapamil, a P-gp inhibitor, on the pharmacokinetics of phenformin were also examined in rats. The plasma concentrations of phenformin were increased following oral administration of phenformin and intravenous verapamil infusion compared with those administerd phenformin alone. Pharmacokinetic parameters such as Cmax and AUC of phenformin increased and CL/F and Vss/F decreased as a consequence of verapamil treatment. These results suggested that P-gp blockade by verapamil may decrease the phenformin disposition and increase plasma phenformin concentrations. P-gp inhibition by verapamil treatment also increased plasma lactate concentration, which is a crucial adverse event of phenformin. In conclusion, P-gp may play an important role in phenformin transport process and, therefore, contribute to the modulation of pharmacokinetics of phenformin and onset of plasma lactate level.
Administration, Oral ; Animals ; Area Under Curve ; Diffusion ; Intestinal Absorption ; Lactic Acid* ; LLC-PK1 Cells ; P-Glycoprotein* ; Pharmacokinetics ; Phenformin* ; Plasma* ; Rats ; Swine ; Verapamil

OBJECTIVES: Banha-sasim-tang (BST), which consists of seven different herbs, is one of the most popular herbal formulae for treating gastrointestinal disorders in Eastern Asia. The commonly used herbal medicine is often co-administered with other therapeutic drugs, which raises the possibility of herb–drug interactions and may modify the clinical safety profile of therapeutic drugs. METHODS: We investigated the potential herb–drug interactions between BST extract and midazolam (MDZ) in mice. The area under the plasma concentration-time curve (AUC) of MDZ and 1ʹ-hydroxymidazolam (1ʹ-OH-MDZ) was evaluated for both oral and intraperitoneal administration of MDZ, following oral administration of BST (0.5 and 1 g/kg). RESULTS: It was found that the AUC of MDZ and 1ʹ-OH-MDZ was lower in case of oral administration of MDZ. Administration of BST extract was not associated with hepatic cytochrome P450 activity. BST extract induced a strong reduction in pH and it has been reported that oral mucosal absorption of MDZ is lower at low pH. The decreased absorption rate of MDZ might be caused by the ingredients of BST and may not be related to other factors such as increased excretion of MDZ by P-glycoprotein. CONCLUSIONS: The altered pharmacokinetics of midazolam caused by co-administration with BST in vivo could be attributed to a decrease in pH and subsequent reduction of MDZ absorption rate.
Absorption* ; Administration, Oral ; Animals ; Area Under Curve ; Cytochrome P-450 Enzyme System ; Far East ; Herb-Drug Interactions ; Herbal Medicine ; Hydrogen-Ion Concentration* ; Mice ; Midazolam* ; Oral Mucosal Absorption ; P-Glycoprotein ; Pharmacokinetics ; Plasma ; Stomach*

PURPOSE: Traditional chemotherapy is the main adjuvant therapy for the treatment of non-small cell lung cancer (NSCLC). However, the emergence of multi-drug resistance (MDR) has greatly restricted the curative effect of chemotherapy. Therefore, it is necessary to find a method to treat MDR NSCLC clinically. It is worth investigating whether NSCLCs that are resistant to traditional chemotherapy can be effectively treated with tyrosine kinase inhibitors targeting epidermal growth factor receptor (EGFR). MATERIALS AND METHODS: The expression of P-glycoprotein (P-gp) and lung resistance-related protein (LRP) was detected by immunohistochemistry, and mutations in EGFR (exons 19 and 21) and Kirsten rat sarcoma viral oncogene homolog (KRAS) (exon 2) were detected by high-resolution melting analysis (HRMA) of surgical NSCLC specimens from 127 patients who did not undergo traditional chemotherapy or radiotherapy. A Pearson chi-square test was performed to analyze the correlations between the expression of P-gp and LRP and mutations in EGFR and KRAS. RESULTS: The expression frequencies of P-gp and LRP were significantly higher in adenocarcinomas from non-smoking patients; the expression frequency of LRP was significantly higher in cancer tissue from female patients. The frequency of EGFR mutations was significantly higher in well to moderately differentiated adenocarcinomas from non-smoking female patients. The frequency of EGFR mutations in the cancers that expressed P-gp, LRP, or both P-gp and LRP was significantly higher than that in cancers that did not express P-gp or LRP. CONCLUSION: NSCLCs expressing P-gp/LRP bear the EGFR mutation in exon 19 or 21 easily.
Aged ; Aged, 80 and over ; Carcinoma, Non-Small-Cell Lung/*genetics/surgery ; Exons/*genetics ; Female ; Humans ; Lung Neoplasms/*genetics/pathology/surgery ; Middle Aged ; Mutation ; P-Glycoprotein/*genetics ; Protein Kinase Inhibitors/therapeutic use ; Proto-Oncogene Proteins/*genetics ; Proto-Oncogene Proteins p21(ras) ; Receptor, Epidermal Growth Factor/*genetics ; Treatment Outcome ; Vault Ribonucleoprotein Particles/*genetics ; ras Proteins/*genetics