Vitamin D Deficiency Increases Risk of Tumor Growth and Metastasis in Breast Cancer
In mouse and cell culture models of breast cancer, deficiency in vitamin D resulted in tumors that grew faster and were more likely to metastasize, according to a recent study. This study, published in Endocrinology, also demonstrated a correlation between serum vitamin D levels and inhibitor of differentiation 1 (ID1), a tumor growth gene known to be correlated with breast cancer tumors and metastases.1
Breast cancer risk and low serum vitamin D levels have previously been associated in humans. In fact, patients with breast cancer often are deficient in vitamin D on diagnosis.
In mice, vitamin D signaling inhibited the expression of ID1. When these mice were deficient in serum vitamin D, due to a vitamin-D-deficient diet, ID1 expression was no longer suppressed.
Researchers ablated the vitamin D receptor in a cell culture model of breast cancer and discovered accelerated primary tumor growth and increased metastases. These results suggested that vitamin D deficiency acts in a cell autonomous manner, rather than systematically, to affect breast cancer.
"Although much more research needs to be done, research from our lab and others suggests that people at risk for breast cancer should know their vitamin D levels and take steps to correct any deficiencies," said Brian Feldman, MD, PhD, assistant professor of pediatrics, Department of Pediatrics, Stanford University, Stanford, California.
In human breast cancer cell cultures, the mechanism by which vitamin D regulated ID1 was evolutionarily conserved.
"Our study shows that a deficiency in vitamin D levels, or an inability of tumor cells to respond appropriately to the presence of vitamin D, is sufficient to trigger non-metastatic cancer cells to become metastatic," stated Feldman.
"It's enough to significantly accelerate tumor progression in our mouse model. Further studies are warranted, but this direct association between vitamin D levels and ID1 expression is very interesting to us."
1. Williams JD, Aggarwal A, Swami S, et al. Tumor autonomous effects of vitamin D deficiency promote breast cancer metastasis [published online ahead of print March 2, 2016]. Endocrinology. doi:10.1210/en.2015-2036