Assessment of ecotoxicity effects of aspirin on non-target organism (Daphnia magna) via analysis of the responses of oxidative stress, DNA methylation-related genes expressions and life traits changes

Aspirin (acetylsalicylic acid, ASA), a widely used non-steroidal anti-inflammatory drug, was frequently detected in aquatic environments around the world. However, information on the potential toxic effects of aspirin on non-target aquatic invertebrates is limited. In the present study, we investigated the effects of ASA on the transcriptional expressions of antioxidant genes (Nrf2, Keap1, HO-1, GCLC, GPx, TRX, TrxR and Prx1) and DNA methylation genes (DNMT1, DNMT3 and TET2) in Daphnia magna (D. magna)for 24, 48 and 96 h and the changes of antioxidant enzymatic activity and GSH, MDA content for 48 h. The effects of ASA on the life traits of D. magna were also addressed via a 21-days chronic toxicity test. Results showed that the expressions of Nrf2 and its target genes (HO-1, GPx and TrxR, GCLC, TRX and Prx1) were induced to different degrees at 48 h and/or 96 h. The activity of antioxidant enzymes (SOD, CAT, GST and GPx) and MDA content increased but GSH content decreased, indicating that ASA caused oxidative stress in D. magna. ASA also changed the expression of DNA methylation genes, such as DNMT and TET2, in D. magna. We speculated that ASA may affect the antioxidant system responses through regulation of Nrf2/Keap1 signaling pathway, and/or through indirectly influencing DNA methylation levels by DNMT and TET gene expression, but the detailed mechanism needs further investigations. Chronic exposure to ASA for 21 days caused inhibitions on the growth, reproduction and behavior of D. magna (e.g., delaying days to the first brood and shortening the body length). In summary, ASA significantly affected the antioxidant responses of D. magna, and negatively disturbed its life traits in growth, development and reproduction.

Abstract 4837: Integrated genome sequence, epigenome, and transcriptome map of bladder cancer development

Genomic maps that track the development of human cancer from its in situ precursor conditions to invasive disease can facilitate the search for genes and genomic sequences involved in the development of cancer. The identification of those chromosomal regions and their positional target genes as well as non-coding sequences that provide growth advantage for the incipient preneoplastic conditions can provide novel insights on molecular mechanisms of cancer development. Such an approach is also critical for the identification of novel biomarkers as well as targets for preventive and therapeutic strategies.

We report on the construction of a high resolution whole-organ histologic and genetic map of bladder cancer development that tracks its progression from in situ precursor conditions to invasive clinically aggressive cancer using exome deep sequencing and 1M SNP-based Illumina genotyping combined with CpG island methylation and cDNA microarray technology platforms. This approach provided a high resolution integrated pattern of structural genome, epigenome, and transcriptome alterations that parallel the development of bladder cancer from early field effects to invasive disease.

By analyzing genome-wide patterns of structural genomic (copy loss or gain), epigenomic, and transcriptome changes, we found three major waves of alterations associated with growth advantage of successive clones reflecting a stepwise conversion of normal urothelial cells into cancer cells. In particular, this approach is significant for the identification of specific chromosomal regions as well as epigenetically and transcriptionally modified gene ontologies involved in early clonal expansion of intraurothelial neoplasia and their clonal evolution to carcinoma in situ progressing to invasive cancer. These studies suggest involvement of ras/raf gene network in early clonal expansion of intraurothelial neoplasia.

This map represents a prerequisite for specific studies on the mechanisms of incipient phases of bladder cancer development and should have a significant impact on the understanding of human carcinogenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4837. doi:10.1158/1538-7445.AM2011-4837