Investigators have found that vitamin D deficiencies may contribute to more aggressive prostate cancer in Black patients at a younger age compared with White patients, according to a new study published by Siddappa et al in Cancer Research Communications. The new findings could pave the way for revised nutritional guidelines.
Background
“[Black patients] are more likely than [White patients] to develop prostate cancer, and are twice as likely to die from the disease,” explained senior study author Moray Campbell, PhD, a research scientist at Cedars-Sinai Cancer. “Large-scale studies have shown that differences in access to health care do not fully account for this health disparity, and our study identifies biological factors that might explain it,” he added.
Vitamin D helps the body absorb calcium but may also helps stimulate the maturation of cells. Unlike normal cells, cancer cells do not mature and die. They continue to divide, creating more abnormal cells.
“Without sufficient levels of vitamin D to cause them to mature, the cells in a tumor continue to multiply out of control,” Dr. Campbell said. He and his team discovered that the vitamin D receptor—a protein that helps the body use vitamin D—appears to have adapted differently in Black patients than in White patients.
“The forebears of [Black patients and White patients] adapted to the climates where they originated,” Dr. Campbell described. “[Individuals of African descent] retain higher melanin levels in the skin to protect against the … sun, which also helps the body produce vitamin D. Because of this, their descendants in the United States—which receives fewer hours [of bright sunshine] per year … than African countries do—are often vitamin D deficient,” he explained.
Study Methods and Results
In the new study, the investigators examined the prostate cancer cells of Black patients and White patients and uncovered differences between how these groups of cells reacted to exposure to vitamin D.
“Their response to vitamin D was very, very different, including which genes the vitamin D receptor was controlling and the magnitude of that control. In [Black patients], this differing response made them more vulnerable to prostate cancer,” Dr. Campbell emphasized.
While previous studies have investigated vitamin D deficiencies in the context of health disparities, the new study is one of the first to comparatively investigate its functions in a genome-wide manner across Black patients and White patients.
Conclusions
The investigators noted that more studies could lead to a revision of nutritional guidelines for vitamin D intake—for both bone and prostate health—based on genetic ancestry. Additionally, continued research may be needed to determine the level of vitamin D that would be most beneficial for each group and to examine how the vitamin D receptor may work with other proteins associated with prostate cancer.
The investigators plan to further analyze a group of microRNAs in regions of the genome regulated by the vitamin D receptor as well as examine vitamin D and its relationship to health disparities in other hormone-dependent cancers, such as breast cancer. They recently discovered an association between microRNAs and prostate cancer that could eventually be used to develop blood tests offering a more complete picture of prostate health.
Disclosure: The research in this study was supported by grants from the prostate program at the Department of Defense Congressionally Directed Medical Research Programs, the National Institute on Minority Health and Health Disparities of the National Institutes of Health, the National Cancer Institute of the National Institutes of Health, the Department of Defense, and the National Institutes of Health Cancer Center Support. For full disclosures of the study authors, visit aacrjournals.org.
