Effects of cadmium on calcium transporter SPCA, calcium homeostasis and ß-casein expression in the murine mammary epithelium.

Maternal cadmium (Cd) exposure during lactation causes neurobehavioral effects in the suckling offspring as well as involution like disturbances in the mammary glands of rodents. The aim of the present study was to examine Cd-induced effects in secreting mammary epithelial cells in relation to calcium (Ca) transport and ß-casein expression. Reduced protein expression of secretory pathway Ca-ATPase (SPCA) was revealed in the mammary glands of lactating mice exposed to Cd during peak lactation. In concordance, SPCA gene expression was down regulated and total intracellular Ca levels reduced in murine mammary epithelial HC11 cells treated with Cd for 72 h. Cd reduced ß-casein gene expression in a concentration dependent manner in the HC11 cells. Our findings on Cd-induced reduction of Ca levels, SPCA and ß-casein expression in the mammary epithelium resemble the effects observed in the mammary glands as a result of forced weaning. In conclusion, maternal Cd exposure during lactation may disturb Ca regulation and decrease the levels of ß-casein in milk with potential nutritional and developmental implications for the breast-fed newborn.