The impact of genetics, environmental, and geographical factors on inter-individual and inter-ethnic differences in CYP2C9-catalysed drug metabolism

Inter-individual and inter-ethnic variations in drug metabolism are creating an obstacle in providing efficient and effective drug treatments especially for drugs with narrow therapeutic windows. This thesis is contributes to the understanding of the molecular mechanism of these variations. Paper I is an introduction to the inter-individual and inter-ethnic differences in CYP2C9 catalysed drug metabolism. Wide inter-individual differences were observed in the metabolic ratio of losartan to E-3174 metabolite even among individuals who were not carrying defective alleles CYP2C9*2 and CYP2C9*3. Inter-ethnic variation was observed in the metabolism of losartan between CYP2C9 wild type Koreans and Swedes. An allelic variation in the intronic region between exon 8 and 9 of CYP2C9, IVS8-109A>T was observed to cause a lower CYP2C9 activity in Swedes but not Koreans. Paper II studied the combination of age, CYP2C9 genotype, ethnicity, smoking habit, weight and sex as a predictor of CYP2C9 metabolic ratio variability. Ethnicity was the main significant factor influencing between subject-variability in CYP2C9 enzyme activity. Additionally, CYP2C9 genotype and smoking were significant contributors to the variation. Grouping the subjects based on their ethnicity, we found that CYP2C9 genotype is a major predictor for both Koreans and Swedes (27% and 40% of the variability respectively). The smoking effect was non-significant in the Swedes but remains as a factor in the Koreans. The reason behind the smoking effect in Koreans is unidentified. Paper III investigated the possibility of Behcet’s disease as a CYP2C9 inducer. A Swedish ultra-rapid CYP2C9 metaboliser was diagnosed with this disease and this study tested the possibility in Turkish healthy subjects to have a lower CYP2C9 activity than Behcet’s disease patients. Interestingly, the Behcet’s disease patients were shown to have a significantly low CYP2C9 metabolic activity. The factors of genetics, medication and inflammation-related biomolecules are suspected to have caused this down-regulation. We did not find evidence of CYP2C9 genotype and typical Behcet’s disease medication, colchicine having any influence on the observed low CYP2C9 metabolic activity. It is very possible that inflammation response agent caused this inhibitory effect on CYP2C9 activity. Paper IV investigated the effect of the P450 oxidoreductase (POR)*28 variant on the metabolic activity of CYP2C9. We screened all Swedish and Koreans CYP2C9*1/*1 subjects for POR* 5, *13 and *28. No subject was found to carry *5 or *13. Interestingly, Swedish individuals who carry POR*28 allele were observed to display a 1.40 fold increase in CYP2C9 enzyme activity compared to none-POR*28 carriers. We screened the ultra-rapid metaboliser for this variant and she was also a carrier of this variant. More studies should be done to investigate the effect of other SNPs in POR gene to the metabolic activity of drug metabolising enzymes

Single nucleotide polymorphism (SNPS) analysis of Mu-opioid receptors (OPRM1) using denaturing high performance liquid chromatography (DHPLC) among the intravenous drug users

Objectives: The genetic polymorphisms of OPRM1 among the intravenous drug users (IVDUs) and healthy controls were investigated and the risk of addiction in relation to OPRM1 was predicted. Methods: PCR-denaturing high performance liquid chromatography (DHPLC) method was developed to investigate SNPs in the coding regions of OPRM1 in 93 IVDUs and 100 healthy controls. Subjects were confirmed to be drug addicts and their personality was studied using validated Tridimensional Personality Questionnaires (TPQ). Results: Based on the results obtained, seven SNPs were detected; two of them were previously associated with addiction. Homozygous OPRM1:c.118GG and heterozygous OPRM1:c.118AG variants were found to have higher frequencies among the IVDUs and healthy controls. In addition, carriers of OPRM1:c.118G allele scored higher for novelty seeking (NS) and harm avoidance (HA) with more explorative, neurotic and uninhibited personalities. We identified a new variant of OPRM1:c.77C>G which is located at the N-terminus of the G-coupled protein receptor and possibly decreases the binding affinity of its ligands among the IVDUs. Conclusion: In conclusion, DHPLC allows the detection of new and existing variants of OPRM1. Genotyping of OPRM1:c.118A>G and assessment of personalities using TPQ provide valuable tools for determination of addiction risk

Therapeutic potentials of iridoids derived from Rubiaceae against in vitro and in vivo inflammation: A scoping review

Acute inflammation may develop into chronic, life-threatening inflammation-related diseases if left untreated or if there are persistent triggering factors. Cancer, diabetes mellitus, stroke, cardiovascular diseases, and neurodegenerative disorders are some of the inflammation-related diseases affecting millions of people worldwide. Despite that, conventional medical therapy such as non-steroidal anti-inflammatory drugs (NSAIDs) is associated with serious adverse effects; hence, there is an urgent need for a newer and safer therapeutic alternative from natural sources. Iridoids are naturally occurring heterocyclic monoterpenoids commonly found in Rubiaceae plants. Plant extracts from the Rubiaceae family were demonstrated to have medicinal benefits against neurodegeneration, inflammation, oxidative stress, hyperglycaemia, and cancer. However, the therapeutic effects of natural iridoids derived from Rubiaceae as well as their prospective impacts on inflammation in vitro and in vivo have not been thoroughly explored. The databases of PubMed, Scopus, and Web of Science were searched for pertinent articles in accordance with PRISMA-ScR guidelines. A total of 31 pertinent articles from in vitro and in vivo studies on the anti-inflammatory potentials of iridoids from Rubiaceae were identified. According to current research, genipin, geniposide, and monotropein are the most researched iridoids from Rubiaceae that reduce inflammation. These iridoids primarily act by attenuating inflammatory cytokines and mediators via inhibition of the NF-κB signalling pathway in various disease models. A comprehensive overview of the current research on the anti-inflammatory properties of iridoids from the Rubiaceae family is presented in this review, highlighting the characteristics of the experimental models used as well as the mechanisms of action of these iridoids. To develop an alternative therapeutic agent from iridoids, more studies are needed to elucidate the effects and mechanism of action of iridoids in a wide variety of experimental models as well as in clinical studies pertaining to inflammation-related diseases

Systematic pharmacogenomics analysis of a Malay whole genome: proof of concept for personalized medicine.

BACKGROUND: With a higher throughput and lower cost in sequencing, second generation sequencing technology has immense potential for translation into clinical practice and in the realization of pharmacogenomics based patient care. The systematic analysis of whole genome sequences to assess patient to patient variability in pharmacokinetics and pharmacodynamics responses towards drugs would be the next step in future medicine in line with the vision of personalizing medicine. METHODS: Genomic DNA obtained from a 55 years old, self-declared healthy, anonymous male of Malay descent was sequenced. The subject's mother died of lung cancer and the father had a history of schizophrenia and deceased at the age of 65 years old. A systematic, intuitive computational workflow/pipeline integrating custom algorithm in tandem with large datasets of variant annotations and gene functions for genetic variations with pharmacogenomics impact was developed. A comprehensive pathway map of drug transport, metabolism and action was used as a template to map non-synonymous variations with potential functional consequences. PRINCIPAL FINDINGS: Over 3 million known variations and 100,898 novel variations in the Malay genome were identified. Further in-depth pharmacogenetics analysis revealed a total of 607 unique variants in 563 proteins, with the eventual identification of 4 drug transport genes, 2 drug metabolizing enzyme genes and 33 target genes harboring deleterious SNVs involved in pharmacological pathways, which could have a potential role in clinical settings. CONCLUSIONS: The current study successfully unravels the potential of personal genome sequencing in understanding the functionally relevant variations with potential influence on drug transport, metabolism and differential therapeutic outcomes. These will be essential for realizing personalized medicine through the use of comprehensive computational pipeline for systematic data mining and analysis

Summary of the analysis workflow for the Malaysian genome.

<p>Summary of the analysis workflow for the Malaysian genome.</p

Predicted number of potentially damaging and deleterious variants as predicted by computational tools SIFT and Polyphen-2.

<p>Predicted number of potentially damaging and deleterious variants as predicted by computational tools SIFT and Polyphen-2.</p

Database mapping of SNVs found in the Malay individual.

<p>$: Positioning of variations to genomic loci with respect to RefGene.</p>*<p>: Including indels.</p

Summary of SNVs found in the Malay genome and overlaps with dbSNP and 1000 Genome datasets.

<p>Summary of SNVs found in the Malay genome and overlaps with dbSNP and 1000 Genome datasets.</p

Disease risk plot for the Malay genome.

<p>The bars in blue show risk magnitude for alleles showing association with lung cancer while the bars in red show risk magnitude for prostate cancer associated alleles.</p