Prevalence of Low Vitamin D in Patients with Breast Cancer in a Predominantly Hispanic Population at the American-Mexican Border

Vitamin D receptor polymorphisms and associated miRNAs in the development of breast cancer in African American women

Breast cancer (BCa) is a prevalent form of cancer in women, exhibiting varying rates and distribution across different ethnic groups. Among these groups, African American (AA) women have the highest incidence of BCa and the lowest levels of Vitamin D (VD). Numerous studies have explored the connection between variations in the VDR gene and BCa risk, particularly in different populations, but research on the AA population remains limited. Epigenetic modifications, including specific microRNAs (miRNAs), can influence gene expression without altering the genetic code and have been implicated in cancer initiation and progression. Our hypothesis suggests that VDR gene variations may increase BCa risk in AA women and that changes in miRNA expression profiles could contribute to BCa development. Using data from the 1000 Genome Project, we identified five VDR gene variants with significant frequency differences between AA and European-American (EA) populations. We genotyped 404 African American BCa cases and controls for five variants using TaqMan® assays. SNPstats assessed their association with BCa risk. The rs1544410 variant's recessive model (A/A) showed a decreased BCa risk in AA (odds ratio 0.33, 95% CI: 0.15-0.73, p-value 0.0041). Conversely, the rs2853563 variant's recessive model (A/A) was linked to an increased BCa risk (odds ratio 4.04, 95% CI: 1.49-10.95, p-value 0.0022). We investigated miRNA expression influenced by VD in HCC1806 Triple-Negative Breast Cancer (TNBC) cell lines with the A/A allele for rs2853563. nCounter® Nanostring technology assessed miRNA profiles after calcitriol treatment. Our results indicated that calcitriol treatment led to reduced expression of six miRNAs, four of which are associated with tumor suppression in the presence of the AA genotype in TNBC cell lines. These findings suggest that specific VDR genotypes could have a potential effect on the miRNAs expression which could potentially serve as markers for cell proliferation in TNBC.

Sun Exposure Is Associated with Reduced Breast Cancer Risk among Women Living in the Caribbean: The Atabey Study in Puerto Rico

BACKGROUND

Though inconsistent, there is evidence that sun exposure is associated with reduced breast cancer risk. Previous studies have been conducted in geographical regions with seasonal variation in UV radiation, including periods of low to no exposure, and among participants mostly of European descent. Puerto Rico has no significant seasonal fluctuation, with continuous exposure to very high UV radiation.

METHODS

We conducted a population-based case-control study of breast cancer among women in metropolitan San Juan, Puerto Rico, examining a cumulative sun exposure index (SEI) based on a comparison of reflectance of sun-exposed and non-exposed skin. A chromameter was used to measure skin reflectance and estimate the difference between constitutive (unexposed) and facultative (exposed) skin pigmentation in 307 cases and 328 controls. Breast cancer risk factors were ascertained with interviewer-administered questionnaires. OR and 95% confidence intervals (CI) were estimated with unconditional logistic regression.

RESULTS

Adjusted breast cancer odds were lower for the highest tertile of the SEI (ORadj = 0.47; 95% CI, 0.29-0.74). Results were similar within strata of estrogen receptor status. In analyses stratified by constitutive skin pigmentation, among participants with darker skin color, breast cancer risk was lower with more sun exposure (ORadj = 0.33; 95% CI, 0.16-0.70).

CONCLUSIONS

We found lower risk of breast cancer associated with greater sun exposure in a population living with high, continuous sun exposure. This beneficial finding should be placed in the context of other effects of sun exposure.

IMPACT

Sun exposure is a modifiable factor that may contribute, directly or indirectly, to lower breast cancer risk.

Circulating Vitamin D Levels and DNA Repair Capacity in Four Molecular Subtypes of Women with Breast Cancer

Vitamin D regulates estrogen synthesis among other mechanisms involved in breast cancer (BC) development; however, no evidence has been found regarding its relationship with DNA repair capacity (DRC). Therefore, the objective of this study was to elucidate whether DRC levels are linked with plasma 25(OH)D levels. BC cases and controls were selected from our BC cohort. DRC levels were assessed in lymphocytes through the host-cell reactivation assay. 25(OH)D levels were measured using the UniCel DxI 600 Access Immunoassay System. BC cases (n = 91) showed higher 25(OH)D levels than the controls (n = 92) (p = 0.001). When stratifying BC cases and controls into low and high DRC categories, BC cases with low DRC (n = 74) had the highest 25(OH)D levels (p = 0.0001). A positive correlation between 25(OH)D and DRC levels was found for the controls (r = 0.215, p = 0.043) while a negative correlation was found for BC cases (r = −0.236, p = 0.026). Significant differences in 25(OH)D levels were observed when stratifying by molecular subtypes (p = 0.0025). Our study provides evidence of a link between 25(OH)D and DRC in BC along with a description of to how 25(OH)D levels vary across subtypes. The positive correlation observed in the control group suggests that 25(OH)D contributes differently to DRC levels once the malignancy is developed.

Clinical significance of serum 25 hydroxyvitamin D in breast cancer: An Indian scenario

Recent evidences suggest a protective mechanism of vitamin D signaling against breast cancer by the autocrine/paracrine manner and may modestly reduce the risk of breast cancer. Despite lots of sunshine, vitamin D deficiency is widespread in India. Moreover, there are limited studies from Indian population regarding circulatory 25(OH) D and breast cancer risk. Thus, the aim of the present study is to investigate circulatory 25(OH) D in relation to breast cancer risk and its association with various clinico-pathological parameters from Indian population. Total 297 subjects, comprising of 157 controls and 140 breast cancer patients were enrolled for the study. Circulatory 25(OH) D was analyzed by HPLC. Statistical analysis was carried out by SPSS software version 15. Further, subjects were categorized into severe, moderate, mild vitamin D deficiency and sufficiency. The prevalence of severe and moderate 25(OH) D deficiency was higher in breast cancer patients as compared to controls. Mean values of 25(OH) D were lower in breast cancer patients as compared to controls in mild, moderate and severe deficient groups (p = 0.07, p = 0.003 and p = 0.001). Moreover, 25(OH) D was significantly lower in postmenopausal breast cancer patients as compared to premenopausal breast cancer patients, particularly in severe deficient group. The levels of 25(OH) D were lower in ER and PR negative receptor status as compared to the positive receptor in severe deficient category (p = 0.06 and p = 0.09 respectively). Whereas, the mean values of 25(OH) D were lower in HER 2 negative receptor status as compared to positive receptor status in the moderate deficient category (p = 0.09). Further, severe deficient group showed significantly lower levels of 25(OH) Din TNBC as compared to luminal A subtype (p = 0.01). Thus, Results indicate that 25(OH) D deficiency might be associated with increased risk of breast cancer. Moreover, severe 25(OH) D deficiency is associated with aggressive behavior of breast cancer.