Supplementary data for: Comparison of phenotypic and transcriptomic profiles between HFPO-DA and prototypical PPARα, PPARγ, and cytotoxic agents in wild-type and Ppara-null mouse livers

Recent in vitro transcriptomic analyses for short-chain per- and
polyfluoroalkyl substances (PFAS), HFPO-DA (ammonium,
2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate) added to the weight
of evidence supporting the peroxisome proliferator-activated receptor
alpha (PPARα) activator-induced hepatocarcinogenesis mode of action (MOA)
for HFPO-DA-mediated liver effects in rodents. Importantly, PPARα-mediated
key events (KEs), including hepatocellular hypertrophy and proliferation
that have been shown to occur prior to tumor development in this MOA, are
rodent-specific and likely not human-relevant. To further inform the MOA
of HFPO-DA and evaluate other hypothesized MOAs, phenotypic and
transcriptomic responses in wild-type (WT) and Ppara-null mice were
investigated following short-term exposure to HFPO-DA or prototypical
agonists of PPARα (GW7647), PPARγ (rosiglitazone), or cytotoxicity
(acetaminophen). Phenotypic and transcriptomic assessment of mouse livers
demonstrated a general lack of response to HFPO-DA or GW7647 exposure in
Ppara-null but not WT mice. Conversely, rosiglitazone or acetaminophen
elicited similar phenotypic and transcriptomic responses between
genotypes, demonstrating a lack of PPARα-dependence. In WT mice,
HFPO-DA-mediated responses were similar to GW7647 but different from
rosiglitazone or acetaminophen. Dose-dependent increases in liver weight,
karyomegaly, and mitosis, as well as increased transcriptomic signaling
related to PPARα activation and cell proliferation, were observed in
HFPO-DA and GW7647-exposed WT mice. The consistent phenotypic and
transcriptomic signaling patterns between HFPO-DA and GW7647 in WT mice,
and the lack of changes in Ppara-null mice, provide further support that
HFPO-DA-mediated early KEs in mouse liver are PPARα-dependent, occur via
the rodent-specific PPARα MOA, and therefore are not appropriate for use
in human health risk assessment.