DESCRIPTION (provided by applicant): Although epidemiological studies have associated arsenic (As) exposures with increased risk of lung cancer, the molecular mechanisms involved in lung cancer development by arsenite exposure remain poorly defined. Recent literature has implicated altered mitochondrial (mt) metabolism, oxidative stress, and DNA damage in environmental As carcinogenesis, but the biochemical dysregulations that underlie these processes and their interactions are unknown. It is also unclear if benchside understanding of As carcinogenesis in model systems can be translated into bedside understanding of human cancer. In this R21/R33 proposal, this team of investigators will address these issues by adopting an integrated `omics approach that uses stable isotope-resolved metabolomics (SIRM) to define mt and cellular metabolic networks central to proliferation, redox homeostasis and oxidative DNA damage/repair response in lung cells, as perturbed by As transformation and carcinogenesis. This approach will reveal pathway changes for further testing on their dysregulations (e.g. key enzymes and related regulatory proteins) at the gene mutational, epigenetic, and transcriptional level by querying into genomic, epigenomic, and transcriptomic sequencing data. The investigators will fulfill their goal with two specific aims (SA1 & 2) in the R21 phase followed by SA3 & 4 in the R33 phase and SA1 to determine if and how mt and cellular metabolic networks are altered in As-transformed lung cells using SIRM. Transformed lung cells will be studied in vitro and in mouse xenografts using SIRM. The reprogrammed metabolic networks obtained will be related to those separately acquired in vivo from human lung cancer patients. SA2) to link ROS production, mt, and nuclear DNA damages/repair processes to metabolic reprogramming in As-transformed lung cells. Correlations of SA1&2 data will enable hypothesis generation for further testing of cause-and-effect relationships in SA3&4. SA3) to reveal cause-and-effect relations among altered Mt/cellular metabolic networks, ROS production, and DNA damage during As-induced transformation by their time-dependence. SA4) to map corresponding genetic, epigenetic and gene expression changes in As-transformed lung cells for hypothesis testing on As action. Next-generation sequence data will be acquired and queried for mutational signatures, epigenetic status, and mRNA expression of key genes involved in the reprogrammed metabolic networks, redox balance, and DNA repair. These data will help delineate how As-induced genetic or epigenetic lesions lead to metabolic reprogramming or vice versa. Such integration of genomic, epigenomic, transcriptomic, and metabolomics analysis of As action in model lung cell systems should provide unprecedentedly detailed insights into metabolic dysregulation and DNA damage in the mitochondria and how they may be linked to nuclear DNA damage and altered gene expression. The integrated `omics information will facilitate full-scale validation studies on the molecular mechanism for As-induced carcinogenesis and translation of such basic insights into human lung cancer resulting from As exposure (e.g. discovery of mechanistic and robust biomarker patterns).

PUBLIC HEALTH RELEVANCE: Environmental carcinogenesis is an important and yet difficult issue to resolve in human health in the US and worldwide due to its extreme complexity. This proposal will take advantage of the latest advances in metabolomics, genomics, epigenomics, and transcriptomics and applies them in an integrated fashion to decipher the molecular etiology of As-induced carcinogenesis. The molecular insights to be acquired will help resolve long-standing gaps of mechanistic knowledge in As action while facilitating the discovery of robust biomarkers as well as preventive and therapeutic measures for at risk populations.