Arsenic-induced Aberrant Gene Expression in Fetal Mouse Primary Liver-Cell Cultures

Exposure of maternal mice to inorganic arsenic through the drinking water induces liver tumors and aberrant gene expression in offspring when they reach adulthood. To help define if these are direct fetal effects of arsenic, fetal liver cells were isolated from untreated mice at gestation day 13.5 by mechanical dissection and centrifugation. Two hours after seeding the cells on collagen1‐coated plates in William E media containing 10% fetal bovine serum, 1x ITS (insulin, transferrin, and selenium) and antibiotics, inorganic arsenite (0, 0.1, 0.3, and 1.0 μM) was added to the fresh media for 72 h. Cell morphology and viability were not significantly altered by these arsenic concentrations. At the end of arsenic exposure, cells were harvested into Trizol, and total RNA was extracted, purified, and subjected to real‐time reverse transcriptase polymerase chain reaction (RT‐PCR) analysis. Arsenite exposure produced a concentration‐dependent induction of heme oxygenase‐1 (up to eight‐fold) and metallothionein‐1 (up to five‐fold), indicative of stress response to adapt to arsenic insult. Expression of genes related to steroid metabolism, such as 17β‐hydroxysteroid dehydrogenase‐7 (HSD17β7) and Cyp2a4, were increased approximately two‐fold, together with increases in estrogen receptor‐α (ER‐α) and ER‐α‐linked genes, such as anterior gradient‐2, keratin 1–19, and trefoil factor‐3. Arsenic in vitro induced a three‐fold increase in the expression of α‐fetoprotein (AFP), a biomarker associated with transplacental arsenic‐induced mouse liver tumors. Thus, exposure of mouse fetal liver cells to arsenic induces adaptive responses and aberrant gene expression, which could alter genetic programming at a very early life stage, potentially contributing to tumor formation much later in life.