Lopes N. et al .– The present review highlights research data concerning the function of Vitamin D hormone in the mammary gland, with a special focus on breast carcinogenesis. Hence, and although the available data are controversial, the authors consider not only updated information on the epidemiology of vitamin D in breast cancer and its potential value as a therapeutic agent or prophylactic (with an emphasis on molecular mechanisms and effectors of vitamin D action), but include data on its role in other stages of breast cancer progression as well. Accordingly, they also review data on the influence of vitamin D in the development of normal breast and the expression of vitamin D–related proteins (VDR, CYP27B1 and CYP24A21) in benign mammary lesions and ductal carcinomas in situ.
- Breast cancer is a heterogeneous disease associated with diverse biological behaviours and clinical outcome.
- Although some molecular subgroups of breast cancer have a targeted therapy, the most aggressive tumours still lack a molecular target.
- Despite vitamin D being classically associated with the physiological role of calcium regulation and phosphate transport in bone metabolism, several studies have demonstrated a wide range of functions for this hormone, which are particularly important in the field of cancer.
- The mechanisms underlying the protective actions of vitamin D in cancer development are only sparsely understood, but evidence shows that vitamin D participates in cell growth regulation, apoptosis and cell differentiation.
- In addition, it has been implicated in the suppression of cancer cell invasion, angiogenesis and metastasis.
- Most of vitamin D biological actions are mediated by the vitamin D receptor and the synthesis and catabolism of this hormone are regulated by the enzymes CYP27B1 and CYP24A1.
- The data described provide evidence for an essential role of vitamin D in normal development of the mammary gland and breast cancer.
- Epidemiological studies are conflicting and their results not consistent, with the current view indicating no protective role for vitamin D in breast cancer development.
- Still, the different functions and effects of vitamin D on cancer cell biology, such as the cell cycle, apoptosis, invasion and metastasis, as well as angiogenesis, virtually bring together the entire spectrum of tumour development under its purview.