A comparison of two human cell lines and two rat gonadal cell primary cultures as in vitro screening tools for aromatase modulation.

Environmental toxicants are a serious health concern, and numerous studies have been devoted to studying the effects of environmental Endocrine Disrupting Chemicals (EDCs). The balance between androgens and estrogens controls the function of many EDC-sensitive organs, and the aromatase enzyme plays a key role in maintaining this balance. In vitro studies have suggested that aromatase expression and activity is a promising biomarker for initial screenings of putative hormonal disrupting compounds. To further validate the aromatase biomarker, we tested several EDCs (atrazine, bisphenol A, methoxychlor, methoxychlor metabolite HPTE, vinclozolin, vinclozolin metabolite M2) in four different models (human cell lines H295R and JEG-3, rat primary cultures of granulosa and leydig cells). We evaluated the similarities/differences in the chemical impact on aromatase mRNA levels and enzymatic activity for the different species and cell types. Aromatase gene expression was assessed by q-RT-PCR, and enzymatic activity was assessed via a tritiated water method with either intact cells or isolated microsomes. The aromatase gene mRNA levels and cellular enzymatic activity varied between the four different models tested, which suggests that the EDC effect varies among different cell types. However, regulation of microsomal aromatase activity appeared to be conserved across all the species and cell types tested. These results suggest that several well characterized complementary cellular models are required to fully characterize the effects of putative EDCs and predict the in vivo effects.