The mechanisms leading to organ level
toxicities are poorly understood.
In this study, we applied an integrated approach to deduce the molecular
targets and biological pathways involved in chemically induced toxicity
for eight common human organ level toxicity end points (carcinogenicity,
cardiotoxicity, developmental toxicity, hepatotoxicity, nephrotoxicity,
neurotoxicity, reproductive toxicity, and skin toxicity). Integrated
analysis of in vitro assay data, molecular targets and pathway annotations
from the literature, and toxicity–molecular target associations
derived from text mining, combined with machine learning techniques,
were used to generate molecular targets for each of the organ level
toxicity end points. A total of 1516 toxicity-related genes were identified
and subsequently analyzed for biological pathway coverage, resulting
in 206 significant pathways (p-value <0.05), ranging
from 3 (e.g., developmental toxicity) to 101 (e.g., skin toxicity)
for each toxicity end point. This study presents a systematic and
comprehensive analysis of molecular targets and pathways related to
various in vivo toxicity end points. These molecular targets and pathways
could aid in understanding the biological mechanisms of toxicity and
serve as a guide for the design of suitable in vitro assays for more
efficient toxicity testing. In addition, these results are complementary
to the existing adverse outcome pathway (AOP) framework and can be
used to aid in the development of novel AOPs. Our results provide
abundant testable hypotheses for further experimental validation.