Angiotensin Receptor Blockers and the Risk of Cancer: Insights from Clinical Trials and Recent Drug Recalls.

PURPOSE OF REVIEW: The purpose of this review is to familiarize readers with issues surrounding angiotensin receptor blockers (ARBs) and the risk of cancer, both from the perspective of clinical trial data and the more recent concerns about impurities in certain ARB products. RECENT FINDINGS: Approximately 45.6% of adults in the USA have hypertension. ARB-containing medications are widely used in the USA, with tens of millions of prescriptions written yearly. Whether exposure to certain ARB drug products contributes to the development of cancer has been the topic of a series of publications. Nonetheless, ARBs' link to cancer, if any, remains inconclusive. Any mechanistic link between ARBs and cancer is poorly understood, with a variety of basic science studies suggesting that ARBs should exert a protective effect. Due to the presence of potentially carcinogenic nitrosamine impurities in certain ARB products, a series of large recalls in the USA and in countries around the world has occurred since 2018. These recalls have occurred in the context of two recent trends affecting antihypertensive drugs: nearly ubiquitous reliance on generic drugs and increased use of manufacturing facilities in China and India to supply the USA. Despite substantial efforts directed toward understanding whether ARBs have the potential to cause cancer, the available studies do not provide a consistent answer, and a causal link remains speculative. The principal conclusion must be that there is not a definitive signal for cancer associated with ARB exposure, although the possibility has not been fully excluded. The problem of nitrosamine impurities in certain ARB products (and some other drug products) is in need of further investigation, so that the risks can be mitigated by eliminating these impurities from the drug supply chain.

Genetic and Epigenetic Fine Mapping of Complex Trait Associated Loci in the Human Liver.

Deciphering the impact of genetic variation on gene regulation is fundamental to understanding common, complex human diseases. Although histone modifications are important markers of gene regulatory elements of the genome, any specific histone modification has not been assayed in more than a few individuals in the human liver. As a result, the effects of genetic variation on histone modification states in the liver are poorly understood. Here, we generate the most comprehensive genome-wide dataset of two epigenetic marks, H3K4me3 and H3K27ac, and annotate thousands of putative regulatory elements in the human liver. We integrate these findings with genome-wide gene expression data collected from the same human liver tissues and high-resolution promoter-focused chromatin interaction maps collected from human liver-derived HepG2 cells. We demonstrate widespread functional consequences of natural genetic variation on putative regulatory element activity and gene expression levels. Leveraging these extensive datasets, we fine-map a total of 74 GWAS loci that have been associated with at least one complex phenotype. Our results reveal a repertoire of genes and regulatory mechanisms governing complex disease development and further the basic understanding of genetic and epigenetic regulation of gene expression in the human liver tissue.

Biochemical and biophysical properties of positively supercoiled DNA.

In this paper we successfully developed a procedure to generate the (+) supercoiled (sc) plasmid DNA template pZXX6 in the milligram range. With the availability of the (+) sc DNA, we are able to characterize and compare certain biochemical and biophysical properties of (+) sc, (-) sc, and relaxed (rx) DNA molecules using different techniques, such as UV melting, circular dichroism, and fluorescence spectrometry. Our results show that (+) sc, (-) sc, and rx DNA templates can only be partially melted due to the fact that these DNA templates are closed circular DNA molecules and the two DNA strands cannot be completely separated upon denaturation at high temperatures. We also find that the fluorescence intensity of a DNA-binding dye SYTO12 upon binding to the (-) sc DNA is significantly higher than that of its binding to the (+) sc DNA. This unique property may be used to differentiate the (-) sc DNA from the (+) sc DNA. Additionally, we demonstrate that E. coli topoisomerase I cannot relax the (+) sc DNA. In contrast, E. coli DNA gyrase can efficiently convert the (+) sc DNA to the (-) sc DNA. Furthermore, our dialysis competition assays show that DNA intercalators prefer binding to the (-) sc DNA.