<div>The human ether-a-go-go-related gene (hERG, KCNH2) potassium channel has been implicated in diverse physiological and pathological processes. The KCNH2 gene encodes a rectifier voltage-gated potassium channel (Kv 11.1) that governs the chief repolarizing current, IKr, which is essential for normal electrical activity in excitable cells such as cardiomyocytes. It is also involved in cell growth and apoptosis regulation in non-excitable cells, such as tumor cells. Dysfunction of hERG is associated with potentially lethal complications, including diseases and sudden death under certain circumstances. While the mechanisms regulating KCNH2 expression remain unclear, recent data suggested that microRNAs (miRNAs) are involved, particularly in the context of several pathologic effects. </div><div>miRNA is a class of RNA defined by its conserved, short, non-coding nature. miRNAs are important regulators of gene expression at the post-transcriptional level that bind through complimentary annealing to the 3’ untranslated regions (3’ UTRs) of target mRNAs, resulting in mRNA destabilization and translational repression. The primary objectives of this research were to 1) identify miRNAs regulating KCNH2 expression in cancer, 2) investigate the potential association between miR-362-3p expression and risk of drug-induced QT interval lengthening, and 3) identify miRNAs potentially regulating KCNH2 expression and function in cardiac cells. </div><div>Through bioinformatics approaches, five miRNAs were identified to potentially regulate KCNH2 expression and function in breast cancer cells. The five identified miRNAs were validated through a Dual-Luciferase Assay using the KCNH2 3′ UTR. Only miR-362-3p was validated to bind to the KCNH2 3’ UTR, decreasing luciferase activity by 10% ± 2.3 (P < 0.001, n = 3) when compared to cells transfected with luciferase plasmid alone. miR-362-3p was also the only miRNA that its expression positively correlated with overall survival of patients with breast cancer from The Cancer Genome Atlas-Cancer Genome (TCGA) database by log-rank test (HR: 0.39, 95% CI: 0.18 to 0.82, P = 0.012). Cell proliferation was assessed by MTS assay (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) 48 hours following transfection in breast cancer cell lines, including SK-BR-3 and MCF-7. miR-362-3p significantly decreased proliferation of SK-BR-3 and MCF-7 cells by 23% ± 8.7 (P = 0.014, n = 3) and 11.7% ± 1.0 (P < 0.001, n = 3), respectively. Cell cycle phases in SK-BR-3 and MCF-7 cells were differentiated by flow cytometry 48 hours following transfection. miR-362-3p and hERG siRNA (positive control) significantly increased the accumulation of cells in G0/G1 phase in MCF-7 by 11.7% (from 51.1% ± 0.64 to 57.1 ± 0.96, P = 0.002, n = 3) and 10% (from 51.1% ± 0.64 to 56.8 ± 0.96, P < 0.001, n = 3), respectively. </div><div>The demonstrated ability of miR-362-3p to regulate hERG in breast cancer cells coupled with previously published data that indicated an alteration of miR-362-3p expression during HF and a potential association between its expression and QT interval prolongation suggesting an important role for this miRNA in regulation of hERG function during HF. Therefore, the contribution of miR-362-3p to hERG function was investigated in patients administered the QT prolonging drug ibutilide, known to inhibit hERG. A total of 22 patients completed a prospective, parallel-group comparative study during which they received subtherapeutic doses (0.003 mg/kg) of ibutilide. The study was originally designed to investigate the influence of heart failure with preserved ejection fraction (HFpEF) on response to drug-induced QT prolongation. Blood for determination of serum Ibutilide concentrations and miR-362-3p expression, along with electrocardiograms (ECGs) were serially collected over a span of 12 hours. ΔΔ-Fridericia-heart rate corrected QT (ΔΔ QTF) intervals were utilized for all analyses to account for baseline and diurnal variation. </div><div>To assess the ability of miR-362-3p to predict ibutilide QT-induced ΔΔQTF changes, nonlinear mixed effects pharmacokinetic/ pharmacodynamic (PKPD) modeling was performed to assess the contribution of miR-362-3p to drug-induced QT interval lengthening. The model that best fit serum ibutilide concentrations versus time was a 3-compartment model with first order elimination and proportional residual errors, while the model that best described the ibutilide concentration- ΔΔQTF relationship was an Emax model with an effect compartment. In addition to miR-362-3p expression, several demographic and clinical data were evaluated as potential covariates on PK and PD parameter estimates. Of tested covariates, heart failure (HF) status on Emax (ΔOFV = -4.1; P < 0.05), and miR-362-3p expression on EC50 (ΔOFV = -9.9; P < 0.05) were incorporated in the final PKPD model. The mean individual Emax was significantly higher in HF patients when compared to non-HF patients (P = 0.015), while EC50 was negatively correlated with miR-362-3p expression (P < 0.0001, R2 0.93). </div><div>Previous evidence indicates that miR-362-3p is altered in patients with HF. In addition, several miRNAs commonly regulate the same ion channel. Therefore, we have developed a large-scale high-throughput bioassay (HT-bioassay) to explore and identify other miRNAs potentially involved in KCNH2 expression and function in human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM) during sustained β-adrenergic receptor (βAR) stimulation or overexpression of activated calcium/calmodulin-dependent protein kinase 2 (CaMKII), which are classical consequences of HF. </div><div>Through bioinformatic approaches, putative miRNA binding sites (n=327) were identified in the KCNH2 3′ UTR. Fragments containing these putative binding sites were synthesized, cloned into linearized plasmids, and amplified. The plasmid pool was transfected into hiPS-CM cells either treated with βAR stimulation or overexpressing CaMKII. Next-generation sequencing was performed to identify: 1) expression of putative miRNA binding sites and 2) endogenous miRNAs versus control. Eight predicted binding sites were found to be significantly downregulated in the CAMKII group (P <0.05, log fold change -0.287 to -0.59), and six significantly downregulated in the sustained βAR group (P <0.05, log fold change -0.29 to -0.72). Two binding sites were significantly reduced in both treatment groups (P < 0.05, log fold change between -0.38 and -0.61).</div><div>Thirty-one miRNAs were predicted to bind to the 16 binding sites identified from the bioassay. Of these, seven were selected for further screening using dual luciferase assays. None of the putative miRNAs reduced luciferase activity. However, hERG expression was assessed by immunoblot analysis following transfection of the seven miRNAs into HEK293 cells stably expressing hERG (HEK293-hERG). Six of the seven miRNA mimics reduced hERG protein expression. An additional validation step was performed by assessing hERG-related current density by whole cell electrophysiology, in which three of the six miRNAs inhibited hERG protein transfected into HEK293-hERG cells. Those same three miRNA mimics significantly decreased Ikr current (P <0.05). </div><div>Finally, expression of the miRNAs identified by HT-bioassay was examined in the patients enrolled in the clinical trial in which genome-wide next generation sequencing was performed on miRNAs extracted from whole blood samples. Of the 31 miRNAs identified from HT-bioassay, six were found to be expressed in patients (n = 12). A correlation analysis was performed between levels of the expressed miRNAs and corresponding QTF interval lengthening with ibutilide. Of the six miRNAs, only miR-4665-5p was significantly associated with QTF interval (P = 0.0379). </div><div>In summary, miR-362-3p was identified to regulate hERG, and reduces proliferation of breast cancer cells through a mechanism that may be partially mediated by hERG inhibition. While miR-362-3p may have modest effects in cancer, in Aim 2 we demonstrated that it along with HF status accounts for a significant amount of variability in QTF prolongation following ibutilide administration. However, it is common for several miRNAs to regulate a single ion channel. Therefore, an HT-bioassay was developed to identify all miRNAs that potentially regulate KCNH2 during HF. In addition to miR-362-3p, thirty-one miRNAs were predicted to regulate KCNH2; one miRNA (miR-4665-5p) was significantly associated with QTF prolongation. The potential for miR-362-3p and HT-bioassay-identified miRNAs to reduce hERG-related current and influence susceptibility to drug-induced QT interval prolongation warrants further investigation. </div><div><br></div>

Background: Drugs are an important part of treating diseases but can also come with its risks. To reduce the risks, a system assisted pharmaceutical validation (SAPVAL) is being developed at Uppsala University Hospital. This will include the generation of alerts regarding different risks, sent to a clinical pharmacist who assesses whether the alerts should be forwarded to a physician or not. One of the risks included is QT prolongation, a relatively uncommon condition which however can result in sudden cardiac death. Aim: The aim was to map the management and the consequences of QT-related risk prescriptions and to determine the clinical relevance of QT-related alerts. Method: A retrospective cross-sectional study was performed at Uppsala University Hospital. It included the review of patients´ electronic health records (EHR) and determination of risk periods. The clinical relevance of the alerts was assessed by a physician and a developed flowchart. Results: 65 patients (age=71 ± 15 years, 54% women), and their 85 QT-related alerts were included, with a median risk period of 145 days. Within the risk period, 46 patients had an ECG taken with 35% having one or more prolonged QTc ≥ 480 ms. The risk of QT prolongation had been noticed or mitigated for 23% of the 65 patients. 89% of the alerts were concluded to be clinically relevant. Conclusion: The management and documentation of QT-related risks could be improved. It is also important to further study QT-related risk factors to better assess which patients are at the highest risk.

<div>My PhD thesis evolves around the potential protective effects of sex hormones progesterone and testosterone against drug-induced QT interval prolongation in premenopasual women and older men.<br></div>

This project aims to support pharmacovigilance, the science and activities relating to drug-safety and prevention of adverse drug reactions (ADRs). We focus on a specific ADR called QT prolongation, a serious reaction affecting the heartbeat. Our main goal is to group medicinal ingredients that might cause QT prolongation. This grouping can be used in safety analysis and for exclusion lists in clinical studies. It should preferably be ranked according to level of suspected correlation. We wished to create an automated and standardised process. Drug safety-related reports describing patients' experienced ADRs and what medicinal products they have taken are collected in a database called VigiBase, that we have used as source for ingredient extraction. The ADRs are described in free-texts and coded using an international standardised terminology. This helps us to process the data and filter ingredients included in a report that describes QT prolongation. To broaden our project scope to include uncoded data, we extended the process to use free-text verbatims describing the ADR as input. By processing and filtering the free-text data and training a classification model for natural language processing released by Google on VigiBase data, we were able to predict if a free-text verbatim is describing QT prolongation. The classification resulted in an F1-score of 98%. For the ingredients extracted from VigiBase, we wanted to validate if there is a known connection to QT prolongation. The VigiBase occurrences is a parameter to consider, but it might be misleading since a report can include several drugs, and a drug can include several ingredients, making it hard to validate the cause. For validation, we used product labels connected to each ingredient of interest. We used a tool to download, scan and code product labels in order to see which ones mention QT prolongation. To rank our final list of ingredients according to level of suspected QT prolongation correlation, we used a multinomial logistic regression model. As training data, we used a data subset manually labeled by pharmacists. Used on unlabeled validation data, the model accuracy was 68%. Analyzing the training data showed that it was not easily separated linearly explaining the limited classification performance. The final ranked list of ingredients suspected to cause QT prolongation consists of 1086 ingredients.

Les médicaments qui provoquent un allongement de la repolarisation cardiaque, mesuré sur l’électrocardiogramme (ECG) par la prolongation de l’intervalle QT, ont été associés à une augmentation du risque pro-arythmique, et plus particulièrement à la survenue de Torsades de pointes, une tachycardie ventriculaire polymorphe potentiellement mortelle. Les méthodes d'analyse du QT conventionnelles se restreignent à l’extraction de quelques complexes ECG. Cette pratique se traduit par de nombreuses limitations. L’inclusion de tous les battements enregistrés sur 24h et mesurés par des méthodes automatiques de mesure ECG a le potentiel de résoudre ces inconvénients. Ce travail de thèse a démontré que les méthodes de mesure ECG automatisées et les analyses continues peuvent supplanter les méthodes conventionnelles pour l'analyse de la prolongation du QT lors des essais cliniques. Des recommandations ont été établis afin de permettre une utilisation optimale des méthodes d'analyse ECG continues. / Drugs which induce a delay in cardiac repolarization measured as QT interval prolongation on the electrocardiogram (ECG) have been associated with a potential to increase the risk of arrhythmias, especially Torsades de pointes (TdP), a potentially lethal polymorphic ventricular tachycardia. The analyses performed using conventional methods are restricted to the extraction of a few ECG complexes. This practice is associated with several limitations. In contrast, the inclusion of all beats measured by computerized methods from continuous 24 h recordings could resolve all of these deficiencies. The current work demonstrated that automated ECG measurement methods employing continuous analysis can supplant conventional methods for the evaluation of QT prolongation in clinical studies. Recommendations have been established to provide an optimal use of continuous ECG analysis.