Superfund Research Program
Genetic Susceptibility to Superfund Chemicals
Using the revolutionary CRISPR (clustered regularly interspaced short palindromic repeats) genome editing technology, the research team is studying genetic factors that govern susceptibility and response to chemical exposures in a cellular system. They have developed and applied both genome-wide and targeted CRISPR to perform functional screening of arsenic (As), acetaldehyde (AA) and formaldehyde (FA) toxicity. GSR trainee, Amin Sobh, has used the genome-wide CRISPR-Cas9 knockout tool to identify multiple candidate genes and/or pathways that are potentially involved in the mechanisms of As and AA toxicities. KEAP1 (kelch-like ECH-associated protein 1), a gene associated with lung papillary adenocarcinoma, was determined to mediate the response to As with multiple hits. SEPHS2 (selenophosphate synthetase 2) and SECISBP2 (SECIS binding protein 2), selenium-associated genes, also mediated sensitivity to arsenic exposure. This led the research team to hypothesize that these selenium-contained proteins may interact with arsenic and attenuate its toxicity via an anti-oxidation pathway. Together, these genes provided a potential mechanistic understanding of arsenic-associated lung cancer. Amin is currently using a targeted secondary screening approach to validate these results obtained from the primary screens. GSR Pam Chew is using a targeted approach to investigate potential mechanisms of FA-induced DNA damage in FA toxicity using a human cell line edited by CRISPR to lack FANCD2. Pam is also currently testing the role of a group of genes that confer resistance to FA.
The research team has also developed a toxicology-specific CRISPR library (ToxCRISPR) which combines the environmentally responsive human “S1500+” gene set prioritized by NIEHS/NTP/Tox21 program as being involved in drug and chemical response with 647 Environmental Genome Project (EGP) genes and a few other selected cancer related genes, resulting in 3,675 genes. Two ToxCRISPR libraries have been generated using sgRNA designs – one resulting in inactivation of target genes and another producing activation of target genes – and now are being tested in human cell lines to assess their utility.