The role of vitamin D in health and disease is still being explored, but it is definitely not a myth: vitamin D modulates some of the characteristics of cancer, and its anti-cancer functions include inhibition of cell proliferation, invasion, metastasis and angiogenesis, and induction of apoptosis and differentiation of cells. Vitamin D prevents and attacks breast cancer”.
Although, some studies do not support a causal relationship between vitamin D intake or supplementation and the risk of breast cancer, a large number of studies have shown a potential protective effect of vitamin D in breast cancer patients and hypothesized that disruption of vitamin D signaling pathways is a driving factor in disease progression. Regarding the relationship between vitamin D and breast cancer, let’s take a look at the overview of foreign studies and our findings…
I. Sources and metabolism of vitamin D
The discovery of vitamin D was the result of people’s struggle with rickets. As early as 1824, it was discovered that cod liver oil could play an important role in the treatment of rickets. 1918, Sir Mellanby in England confirmed that rickets was a nutritional deficiency. However, he mistakenly believed that it was due to vitamin A deficiency.
The chemical structure of vitamin D was first determined by Professor A. Windaus of Gottingen University in 1930, and the chemical properties of vitamin D2, obtained by ultraviolet irradiation of ergosterol, were elucidated in 1932. The chemical properties of vitamin D3 were not determined until 1936.
(1) Endogenous synthesis by sunlight through the skin
UVB at wavelengths of 300+ 5 nm converts 7-dehydrocholesterol into vitamin D3 precursors at the base of the epidermis. It is the most important source form of vitamin D.
(2) Food intake via the small intestine
Food sources include oil-rich fish such as salmon, eggs, and fortified dairy products. The two forms of vitamin D found in nature include animal-derived vitamin D3 and plant-derived ergocalciferol.
II. The role of vitamin D in health
In recent years, there is increasing evidence that vitamin D is not only involved in calcium and phosphorus metabolism in the body, but that vitamin D deficiency may be extremely harmful to the body. It is believed that the formation of diseases such as cancer, heart disease, lung disease, diabetes, hypertension, schizophrenia and multiple sclerosis are closely related to vitamin D deficiency.
Mechanism of vitamin D molecular action
1. Gene regulation of vitamin D – through binding to VDREs
The classical form of vitamin D regulation;
There are many target genes, which affect many different cellular processes, such as cell proliferation and apoptosis.
2. Non-gene regulation of vitamin D – by binding to non-nuclear VDRs, membrane-associated receptors
For example, it binds to the rapid response steroid binding protein (1,25D3-MARRS) receptor; affects intracellular signaling pathways such as phosphorylation, Ca2+, cyclic guanosine, and MAP kinase, Wnt, Hedgehog, Notch, etc.
The regulation of important genes by vitamin D may delay the onset of age-related
fractures, ectopic calcification, malignancies, oxidative damage, infections, autoimmunity, inflammation, pain, cardiovascular diseases, neurodegenerative diseases …….
Anti-tumor effects of vitamin D
Increasing serum 25(OH)D by 25 nmol/L reduced the incidence of all cancers by 17%;
Increasing serum 25(OH)D by 25 nmol/L reduced the mortality rate of all cancers by 29%.
Vitamin D and breast cancer
1. Breast cancer epidemiology
Breast cancer is a common malignant tumor in women
1.2 million women worldwide develop breast cancer and 500,000 die from it every year
High prevalence in North America and Northern Europe, 4 times higher than Asia, Africa and Latin America
Highly prevalent in Shanghai and Beijing in China
Breast cancer is more common in women and less common in men
It is rare before 20 years of age, but the incidence rate increases year by year after 20 years of age, and it is more common in women aged 40-60, especially in late menopause and around menopause.
2.Status of breast cancer in China
In China, the average age of diagnosis of breast cancer is 45-55 years, which is younger than that of Western women. Data from Shanghai and Beijing show two peak incidences of breast cancer, the first occurring between 45-55 years of age and the other between 70-74 years of age, and the median age of breast cancer diagnosis tends to increase. 16.6% of breast cancer patients in China were older than 65 years of age in 2008 (compared to 42.6% in the United States), and this figure will increase to 27.0% by 2030. This figure will increase to 27.0% by 2030.
3. Vitamin D and breast cancer epidemiological studies
Studies of the relationship between solar radiation and breast cancer risk.
Reduced sunlight exposure and a corresponding decrease in the amount of vitamin D synthesized by the skin are accompanied by an increase in breast cancer incidence and mortality.
The level of circulating 1,25(OH)2D3 and the risk of developing advanced breast cancer showed a negative correlation.
The most aggressive breast cancer patients (triple negative breast cancer types and basal-like) had the lowest 1,25(OH)2D3 levels.
IV. Vitamin D deficiency and supplementation
V. Our study results
Our research team used breast cancer cell lines and tissue specimens from breast tumor patients to study the relationship between vitamin D and receptors and breast cancer using different techniques and methods, and found that vitamin D and receptors are closely related to the formation, progression and associated calcification of breast cancer, and are involved in inhibiting the process of breast cancer, and clinical application of vitamin D for breast cancer has also achieved some experience and efficacy.
A case-control study of 25-hydroxyvitamin D, blood calcium, calcium-sensitive receptors and E-calcine mucin and the risk of breast cancer development.
Expression of vitamin D receptors in breast tumors and their clinical significance
The VDR expression in malignant breast tumors was significantly higher than that in benign tumors. It is suggested that VDR may play a role in the development and progression of breast cancer, and its mechanism needs to be further investigated. Clinical factors such as patient’s age, presence of axillary lymph node metastasis, menopause, tumor size and clinical stage were not significantly related to VDR expression.