ABSTRACT
Helicobacter pylori (HP) is known to be a causative bacterium of gastritis and peptic ulcers. The combination treatment consisting of a proton pump inhibitor (PPI), amoxicillin and clarithromycin (CAM) is widely used in eradication therapy, but the eradication fails in some patients. The main causes are CAM resistance of HP and individual variability in PPI metabolism related to the activity of the cytochrome P450 2C19 (CYP2C19) enzyme. In this study, we examined the usefulness of the prediction of the pharmacotherapeutic efficacy using a newly developed analysis system for HP CAM resistance and CYP2C19 genotypes. After obtaining the informed consent from 45 subjects with HP-positive peptic ulcers, biopsy specimens of the gastric mucosa were obtained by endoscopy. HP DNA extracted from the gastric mucosa was examined by the SELMAP-PCR method, the direct sequencing method or the single-nucleotide primer extension (SNuPE) method. HP detection rates by culture and the SELMAP-PCR method were 71% and 100%, respectively. Among 32 cultured HP, CAM resistance was confirmed in 6 samples by the in vitro drug susceptibility test. CAM-resistant gene mutations were also examined by the SELMAP-PCR method using 32 DNAs from cultured HP and the results were consistent with the drug susceptibility test. Among 22 patients, the eradication rate was 77%. Among 4 patients with CAM resistance determined by both the in vitro drug susceptibility test and the SNuPE method, eradication was successful in one intermediate metabolizer (IM), but not in three extensive metabolizers (EMs). Patients were divided into three groups according to their CYP2C19 phenotype: EMs, IMs and poor metabolizers (PMs). The eradication rates for 6 EMs, 12 IMs and 4 PMs were 33.3%, 91.7% and 100%, respectively. Based on these results, the information on CAM resistance in HP and CYP2C19 phenotypes in carriers could predict the pharmacotherapeutic efficacy and probability of eradication. It can then be possible to vary the dosing or to select another drug by the prediction of the pharmacotherapeutic efficacy.
Subject(s)
Anti-Bacterial Agents/pharmacology , Aryl Hydrocarbon Hydroxylases/genetics , Clarithromycin/pharmacology , Drug Resistance, Bacterial/genetics , Helicobacter Infections , Helicobacter pylori , Precision Medicine/methods , Anti-Bacterial Agents/therapeutic use , Clarithromycin/therapeutic use , Cytochrome P-450 CYP2C19 , Gastric Mucosa/microbiology , Genetic Testing/methods , Genotype , Helicobacter Infections/drug therapy , Helicobacter Infections/genetics , Helicobacter pylori/drug effects , Helicobacter pylori/genetics , Humans , Polymerase Chain Reaction , Polymorphism, Single Nucleotide , Treatment OutcomeABSTRACT
The neurotrophic receptor tyrosine kinase B (TrkB) is a cell surface receptor for brain-derived neurotrophic factor (BDNF) with kinase activity. This protein is expressed in various tumors and thought to participate in various cellular processes. In this study, we established 293T cells stably expressing human TrkB to elucidate its intracellular functions. Using this cell system, we examined the biological roles of TrkB and its downstream target molecules. The TrkB expressing cells showed an increased survival rate through increased c-fos mRNA expression by BDNF, which were completely suppressed by TrkB inhibitor. Moreover, the combination of inhibitors of mitogen-activated protein kinase (MEK) and phosphatidylinositol 3-kinase (PI3K) partially reduced both the cell survival rate and c-fos mRNA expression, whereas monotreatment of these reagents could not affect cell survival nor c-fos mRNA expression. These results suggested that TrkB could play a role in c-fos-associated cell survival through both MEK and PI3K pathway. It is conceivable that activation of TrkB has a significant impact on tumorigenesis and metastasis.
