Environmental estrogens exposure alters milk proteins synthesis and their transcriptional regulation during mammary gland in vitro differentiation

ALTAMIRANO GA; GOMEZ AL; MUÑOZ-DE-TORO M; RODRIGUEZ HA; KASS L

Congreso; Xth Meeting of the Latin American Society for Developmental Biology; 2019

Latin American Society for Developmental Biology

There are several human-made chemical compounds with hormonal action. Among them, the plastic monomer and plasticizer Bisphenol A (BPA), and the UV-filter benzophenone-3 (BP3) have been shown to have estrogenic activities. Our aim was to study the effects of BPA or BP3 exposure on the mammary gland functional differentiation using an in vitro model. Mammary organoids were obtained and isolated from 8 weeks-old C57BL/6 female mice using an enzymatic/mechanical digestion. The organoids were cultured on Matrigel with growth medium for 24 hs. Then, the medium was changed to a differentiation one (with prolactin) and exposed to: a) vehicle (0.01% ethanol), b) 10-9 or 10-6M BPA or c) 10-12 to 10-6M BP3 for 72 hs. Milk proteins expression and their DNA methylation (DNAme) status were evaluated. Regarding beta-casein (CSN2) expression, its mRNA level was augmented in both BPA concentrations and 10-12M BP3; and this result was associated with hypomethylation of its promoter. Despite this, its protein expression was increased only in mammary organoids exposed to 10-9M BPA or 10-12M BP3. In contrast, BPA exposure showed a decrease of alpha-lactoalbumin (LALBA) mRNA expression and an increase of DNAme status in different methylation-sensitive sites of the gene. Also,10-9M BPA induced a decrease of LALBA protein expression. Our results demonstrate that BPA or BP3 direct exposure alters milk protein synthesis and its transcriptional regulation during mammary gland in vitro differentiation.