25(OH)D 3 and 1,25(OH) 2D 3 serum concentration and breast tissue expression of 1α-hydroxylase, 24-hydroxylase and Vitamin D receptor in women with and without breast cancer

Abstract

1,25(OH) 2D 3 is an antiproliferative agent that may inhibit proliferation of breast cancer (BC) cells in vitro and BC development in animals. Epidemiological studies have shown a high incidence of BC in people less exposed to solar rays. To unravel the role of Vitamin D 3 in BC patients, we have investigated serum levels of 25(OH)D 3 and its active form 1,25(OH) 2D 3 as well as tissue expression of 1α-hydroxylase, 24-hydroxylase, and Vitamin D-receptor (VDR), determined by semiquantitative RT-PCR, in 88 Brazilian BC patients and 35 women without cancer (submitted to mammoplasties or resection of benign lesions). Median age of women with and without cancer was 51 and 46 years, respectively, and the majority of BC patients were classified as clinical stage II (67%). Although no differences in 25(OH)D 3 serum concentration were found, 1,25(OH) 2D 3 (40 ± 21 pg/ml) levels in BC patients were lower than in women without cancer (53 ± 23). Our results indicate that 24-hydroxylase, VDR and 1α-hydroxylase mRNA tissue expression is similar in both groups and no correlation between 24-hydroxylase, 1α-hydroxilase, and VDR expression in breast tumors was found. A low 1,25(OH) 2D 3 serum concentration seems to be associated to breast cancer, however, the mechanism involved in this regulation is still unclear.