MATERIALS AND METHODS: Caco-2 and LS174T cells lines treated with omeprazole and esomeprazole were used in this study to assess the bacterial attachment of H. pylori within certain incubation periods.
RESULTS: The presence of proton pump inhibitors increased the H. pylori adherence in a time-dependent manner in both Caco-2 and LS174T cell lines. The double inhibition of P-glycoprotein using proton pump inhibitor and P-glycoprotein inhibitor caused low P-glycoprotein expression in the cell lines, resulting in higher H. pylori adherence compared to the control cell lines.
CONCLUSION: Proton pump inhibitors may alter P-glycoprotein expression in the gastrointestinal tract, and subsequently H. pylori adherence on the cell lines, and may contribute to resistance to drug therapy.
OBJECTIVE: The purpose of this study was to investigate the influence of P-gp modulation on the efficacy of treatment regimen.
METHOD: P-gp modulation in rats was performed by using P-gp inducer (150 mg/kg rifampicin) and P-gp inhibitor (10 mg/kg cyclosporine A) for 14 days prior to be infected with Helicobacter pylori (H. pylori). The rats were further divided into groups, which were normal control, vehicle control, antibiotics and omeprazole, antibiotics only and omeprazole only for another 2 weeks of treatment. The ulcer formation and P-gp expression were determined by using macroscopic evaluation and western blot analysis, respectively.
RESULTS: The highest P-gp expression was shown in the induced P-gp rats (2.00 ± 0.68) while the lowest P-gp expression was shown in the inhibited P-gp rats (0.45 ± 0.36) compared to the normal P-gp rats. In all groups, the rats which were infected with H. pylori, had a significant increase (p
METHOD: The main polymorphisms on the cytochrome P450 (CYP) genes, CYP2A6, CYP2B6, CYP2C19, CYP2D6, CYP3A4 and CYP3A5, and the multi-drug resistance 1 gene (MDR1) were genotyped in 78 healthy Vietnamese subjects. Pharmacokinetic metrics were available for CYP2A6 (coumarin), CYP2C19 (mephenytoin), CYP2D6 (metoprolol) and CYP3As (midazolam), allowing correlations with the determined genotype.
RESULTS: In the CYP2 family, we detected alleles CYP2A6*4 (12%) and *5 (15%); CYP2B6*4 (8%), *6 (27%); CYP2C19*2 (31%) and *3 (6%); CYP2D6*4, *5, *10 (1, 8 and 44%, respectively). In the CYP3A family, CYP3A4*1B was detected at a low frequency (2%), whereas CYP3A5 *3 was detected at a frequency of 67%. The MDR1 3435T allele was present with a prevalence of 40%. Allele proportions in our cohort were compared with those reported for other Asian populations. CYP2C19 genotypes were associated to the S-4'-OH-mephenytoin/S-mephenytoin ratio quantified in plasma 4 h after intake of 100 mg mephenytoin. While CYP2D6 genotypes were partially reflected by the alpha-OH-metroprolol/metoprolol ratio in plasma 4 h after dosing, no correlation existed between midazolam plasma concentrations 4 h post-dose and CYP3A genotypes.
CONCLUSIONS: The Vietnamese subjects of our study cohort presented allele prevalences in drug-metabolising enzymes that were generally comparable with those reported in other Asian populations. Deviations were found for CYP2A6*4 compared to a Chinese population (12 vs. 5%, respectively; P = 0.023), CYP2A6*5 compared with a Korean population (15 vs. <1%, respectively; P < 0.0001), a Malaysian population (1%; P < 0.0001) and a Chinese population (1%; P < 0.0001); CYP2B6*6 compared with a Korean population (27 vs. 12%; P = 0.002) and a Japanese population (16%; P = 0.021). Pharmacokinetic metrics versus genotype analysis reinforces the view that the predictive value of certain globally common variants (e.g. CYP2D6 single nucleotide polymorphisms) should be evaluated in a population-specific manner.
PURPOSE: This study outlines CuE's cytotoxic activity against drug-resistant tumor cell lines. Three members of ABC transporters superfamily, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and ABCB5 were investigated, whose overexpression in tumors is tightly linked to multidrug resistance. Further factors of drug resistance studied were the tumor suppressor TP53 and the epidermal growth factor receptor (EGFR).
METHODS: Cytotoxicity assays (resazurin assays) were used to investigate the activity of Citrullus colocynthis and CuE towards multidrug resistant cancer cells. Molecular docking (In silico) has been carried out to explore the CuE's mode of binding to ABC transporters (P-gp, BCRP and ABCB5). The visualization of doxorubicin uptake was done by a Spinning Disc Confocal Microscope. The assessment of proteins expression was done by western blotting analysis. COMPARE and hierarchical cluster analyses were applied to identify, which genes correlate with sensitivity or resistance to cucurbitacins (CuA, CuB, CuE, CuD, CuI, and CuK).
RESULTS: Multidrug-resistant cells overexpressing P-gp or BCRP were cross-resistant to CuE. By contrast, TP53 knock-out cells were sensitive to CuE. Remarkably, resistant cells transfected with oncogenic ΔEGFR or ABCB5 were hypersensitive (collateral sensitive) to CuE. In silico analyses demonstrated that CuE is a substrate for P-gp and BCRP. Immunoblot analyses highlighted that CuE targeted EGFR and silenced its downstream signaling cascades. The most striking result that emerged from the doxorubicin uptake by ABCB5 overexpressing cells is that CuE is an effective inhibitor for ABCB5 transporter when compared with verapamil. The COMPARE analyses of transcriptome-wide expression profiles of tumor cell lines of the NCI identified common genes involved in cell cycle regulation, cellular adhesion and intracellular communication for different cucurbitacins.
CONCLUSION: CuE represents a potential therapeutic candidate for the treatment of certain types of refractory tumors. To best of our knowledge, this is the first time to identify CuE and verapamil as inhibitors for ABCB5 transporter.