Investigators in Brazil and the US explore the mutagenic effects of ultraviolet "A" (UVA) light in a cell line model of xeroderma pigmentosum — a recessively inherited genetic condition marked by lower-than-usual DNA damage repair and increased sunburn risk after UV light exposure. With the help of exome sequencing, the team analyzed mutation types and frequencies in UVA light-exposed and -unexposed cells with xeroderma pigmentosum-related DNA polymerase enzyme deficiencies caused by the so-called xeroderma pigmentosum variant (XP-V). Along with new insights into UVA-related mutagenesis in individuals with the skin condition, the authors saw potential ties between the resulting mutation signature and mutation patterns previously described in human skin cancer cases. "This work provides a detailed evaluation of the UVA-induced increase in point mutations in human cells, especially in cells from XP-V patients, which may help us to understand the increased frequency of skin tumor formation in these patients," they write.
A Chinese Academy of Sciences-led team takes a look at the potential post-transcriptional consequences of synonymous mutations in nearly two dozen cancer types. The team relied on an algorithm called PIVar to search for synonymous variants that impair downstream post-transcriptional regulation in tumor samples from 8,320 patients, uncovering almost 23,000 post-transcriptionally impaired, synonymous variants, or "pisSNVs," spanning more than 2,000 genes. "The functional effect of these pisSNVs and their host genes, as well as significantly altered sub-networks containing pisSNV-hosted genes, were further analyzed for their co-occurrence and relative contribution to the etiology of cancers," the investigators note.
Researchers in the US and India characterize chimeric RNAs in dozens of tissue types from seemingly healthy individuals. Using available RNA sequencing data on nearly 9,500 samples from 53 tissues, profiled for the Genotype-Tissue Expression project, the team identified and validated chimeric RNA in disease-free tissues, focusing in on two chimeras with apparent functional roles for further analyses. "The data from this study provides a large repository of chimeric RNAs present in non-diseased tissues," the authors write, "which can be used as a control dataset to facilitate the identification of true cancer-specific chimeras."