Current Pharmacogenomics and Personalized Medicine (Formerly Current Pharmacogenomics) - Volume 17, Issue 2, 2020

Background: Temozolomide is used as frontline chemotherapy in the management of glioblastoma multiforme (GBM); however, its clinical utility is limited by the occurrence of significant resistance, majorly caused due to direct DNA repair. O6- methylguanine-DNA-methyltransferase (MGMT), a DNA repair protein, mediates this direct repair pathway and reverses the activity of temozolomide. Methods: We characterize and underscore the functional relevance and molecular aspects of MGMT in the development of sensitivity/resistance to temozolomide treatment. We review early translational, as well as clinical, evidence for the role of MGMT in mediating temozolomide resistance in vitro in cell lines, in vivo in small animals as well as in GBM patients. Results: Various approaches have been delineated to mitigate MGMT-induced temozolomide resistance. The most promising means in discovery biology appears to be the co-administration of MGMT inhibitors such as O6 benzyl guanine or lomeguatrib. Surprisingly, the validation of these pharmacologic inhibitors to assess the reversal of chemoresistance by appropriately designed safety and efficacy trials in combination with temozolomide is yet to be demonstrated. Conclusion: Taken together, given the regulation of temozolomide resistance by MGMT, intermediate and late discovery groups may focus their efforts on pharmacologic inhibition of MGMT, singly or in combination with radiotherapy or immunotherapy, to combat temozolomide resistance in GBM patients. In addition, one may speculate that the combined clinical use of temozolomide with a drug regulator-approved MGMT inhibitor as well as an immune checkpoint inhibitor such as nivolumab may prove beneficial. Future studies may also investigate any inter-ethnic variability in population pharmacogenetics of MGMT and pharmacometric approaches to optimize cancer precision medicine.

Objectives: FOXP3 is a gene related to regulatory T cells existing on chromosome X. This meta-analysis, based on genetic association studies, was conducted to investigate the association of FOXP3 polymorphisms with susceptibility to multiple sclerosis (MS). Methods: All genetic association studies covering both FOXP3 and multiple sclerosis terms were searched in PubMed, Web of Science and Google Scholar. The information of genotype frequencies was summarized and results were synthesized through odds ratio (OR). Heterogeneity and publication bias were investigated using I2 scale and Begg's funnel plot, respectively. Results: For rs3761548 -3279 C/A polymorphism, AA/AY genotypes were a risk factor in comparison to CC/CY genotypes (P =0.022; OR =1.752; 95% confidence interval [CI] =1.084-2.830; random). AC genotype was a risk factor in comparison to CC/CY genotypes (P =0.004; OR =1.537; 95% CI =1.145-2.062; random) and homozygote genotypes (P =0.016; OR =1.216; 95% CI =1.038-1.426; fixed). For rs2232365 -924 G/A polymorphism, 2 significant associations were found according to a fixed effect model; of course, they did not remain significant in the random effect model. Conclusion: According to the collected populations, susceptibility to and protection from MS are associated with rs3761548 -3279 C/A upstream polymorphism. However, it should be regarded that this association is ethnicity dependent with low effect size.

Background: The Human Genome Project has unleashed the power of genomics in clinical practice as a choice of individualized therapy, particularly in cancer treatment. Pharmacogenomics is an interdisciplinary field of genomics that deals with drug response, based on individual genetic makeup. Objective: The main genetic events associated with carcinogenesis activate oncogenes or inactivate tumor-suppressor genes. Therefore, drugs should be specific to inactivate or regulate these mutant genes and their protein products for effective cancer treatment. In this review, we summarize how polymedication decisions in cancer treatments based on the evaluation of cytochrome P450 (CYP450) polymorphisms are applied for pharmacogenetic assessment of anticancer therapy outcomes. Results: However, multiple genetic events linked, inactivating a single mutant gene product, may be insufficient to inhibit tumor progress. Thus, genomics and pharmacogenetics directly influence a patient’s response and aid in guiding clinicians to select the safest and most effective combination of medications for a cancer patient from the initial prescription. Conclusion: This review outlines the roles of oncogenes, the importance of cytochrome P450 (CYP450) in cancer susceptibility, and its impact on drug metabolism, proposing combined approaches to achieve precision therapy.

Background: Polymorphisms of selected inflammatory and metabolic genes have been described in the etiology of chronic rhinosinusitis, and these effects can be explained on a pharmacogenetic basis. Objective: The purpose of this study was to examine whether there is an association between inflammatory factors and some of these alleles, by associating these genetic variables with each other. Methods: CYP1A2, CYP2D6, CYP2C19, CYP2C9, CYP3A4, CYP3A5, G6PD, NAT2, UGT1A1, VKORC1, ABCB1, SLCO1B1, APOE, TNF, IL1B, IL6 and IL6R gene polymorphisms were analyzed by PCR. Drug-metabolizing enzymes were classified according to their phenotype. Blood cell counts and biochemical parameters were also considered. Results: Significant differences were found in the CYP1A2 phenotype, with fewer CYP1A2 normal metabolizers (NMs) expressing sinusitis (14.3% vs 30%) and a greater number of CYP1A2 ultra-rapid-metabolizers (UMs)(85% vs 69%); and in TNF, affecting TNF-A/A (4% vs 2%) and TNF-G/G (78% vs 66%) compared with TNF-G/A (19% vs 32%) carriers. 96% of patients with CRS had at least one G allele. When trigenic variables involved in sinusitis were analyzed, statistical differences were found in SLCO1B1-TNFCYP1A2, with a higher proportion of subjects with 1/1-GG-UM (44.3%); and IL1B-TNFCYP1A2 with CC-GG-UM (26%), CT-GG-UM (19.8%) and CC-GG-NM (13.7%) genophenotypes, respectively. Subjects with sinusitis had a higher eosinophil count (308.80 cel/mcL vs 263.14 cel/mcL) and lower HDL levels (265.34 vs 297.85 mg/dL). Conclusion: SLCO1B1-TNF-CYP1A2 and IL1B-TNF-CYP1A2 trigenic clusters may condition the chronicity of sinusitis. Eosinophilia and HDL are factors involved in inflammation, and thus in the development of CRS.

Background: Chronic Myeloid Leukaemia (CML) is associated with the BCRABL1 gene, which plays a central role in the pathogenesis of CML. Thus, it is crucial to suppress the expression of BCR-ABL1 in the treatment of CML. MicroRNA is known to be a gene expression regulator and is thus a good candidate for molecularly targeted therapy for CML. Objective: This study aims to identify the microRNAs from edible plants targeting the 3’ Untranslated Region (3’UTR) of BCR-ABL1. Methods: In this in silico analysis, the sequence of 3’UTR of BCR-ABL1 was obtained from Ensembl Genome Browser. PsRNATarget Analysis Server and MicroRNA Target Prediction (miRTar) Server were used to identify miRNAs that have binding conformity with 3’UTR of BCR-ABL1. The MiRBase database was used to validate the species of plants expressing the miRNAs. The RNAfold web server and RNA COMPOSER were used for secondary and tertiary structure prediction, respectively. Results: In silico analyses revealed that cpa-miR8154, csi-miR3952, gma-miR4414-5p, mdm-miR482c, osa-miR1858a and osa-miR1858b show binding conformity with strong molecular interaction towards 3’UTR region of BCR-ABL1. However, only cpa-miR- 8154, osa-miR-1858a and osa-miR-1858b showed good target site accessibility. Conclusion: It is predicted that these microRNAs post-transcriptionally inhibit the BCRABL1 gene and thus could be a potential molecular targeted therapy for CML. However, further studies involving in vitro, in vivo and functional analyses need to be carried out to determine the ability of these miRNAs to form the basis for targeted therapy for CML.

Background: Multiple Sclerosis (MS) is an inflammatory and demyelinating disease of the central nervous system, and genetic factors play an important role in its susceptibility. The expressions of many inflammatory genes implicated in MS are regulated by microRNA (miRNAs), whose function is to suppress the translation by pairing with miRNA Recognition Elements (MREs) present in the 3' untranslated region (3'UTR) of target mRNA. Recently, it has been shown that the Single Nucleotide Polymorphism (SNPs) present within the 3'UTR of mRNAs can affect the miRNA-mediated gene regulation and susceptibility to a variety of human diseases. Objective: The aim of this study was to analyze the SNPs within the 3'UTR of miRNA inflammatory target genes related to multiple sclerosis. Methods: By DisGeNET, dbGaP, Ovid, DAVID, Web of knowledge, and SNPs databases, 3'UTR genetic variants were identified in all inflammatory genes associated with MS. Also, miRNA's target prediction databases were used for predicting the miRNA binding sites. Results: We identified 125 SNPs with MAF>0.05 located in the binding site of the miRNA of 35 genes among 59 inflammatory genes related to MS. Bioinformatics analysis predicted 62 MRE-modulating SNPs and 59 MRE-creating SNPs in the 3'UTR of MSimplicated inflammatory genes. These candidate SNPs within miRNA binding sites of inflammatory genes can alter the miRNAs binding, and consequently lead to the mRNA gene regulation. Conclusion: Therefore, these miRNA and MRE-SNPs may play important roles in personalized medicine of MS, and hence, they would be valuable for further functional verification investigations.