Meta-analysis on vitamin D receptor and cancer risk: focus on the role of TaqI, ApaI, and Cdx2 polymorphisms

Vitamin D in Cancer Prevention and Treatment: A Review of Epidemiological, Preclinical, and Cellular Studies

BACKGROUND

Inhibition of human carcinomas has previously been linked to vitamin D due to its effects on cancer cell proliferation, migration, angiogenesis, and apoptosis induction. The anticancer activity of vitamin D has been confirmed by several studies, which have shown that increased cancer incidence is associated with decreased vitamin D and that dietary supplementation of vitamin D slows down the growth of xenografted tumors in mice. Vitamin D inhibits the growth of cancer cells by the induction of apoptosis as well as by arresting the cells at the G0/G1 (or) G2/M phase of the cell cycle. Aim and Key Scientific Concepts of the Review: The purpose of this article is to thoroughly review the existing information and discuss and debate to conclude whether vitamin D could be used as an agent to prevent/treat cancers. The existing empirical data have demonstrated that vitamin D can also work in the absence of vitamin D receptors (VDRs), indicating the presence of multiple mechanisms of action for this sunshine vitamin. Polymorphism in the VDR is known to play a key role in tumor cell metastasis and drug resistance. Although there is evidence that vitamin D has both therapeutic and cancer-preventive properties, numerous uncertainties and concerns regarding its use in cancer treatment still exist. These include (a) increased calcium levels in individuals receiving therapeutic doses of vitamin D to suppress the growth of cancer cells; (b) hyperglycemia induction in certain vitamin D-treated study participants; (c) a dearth of evidence showing preventive or therapeutic benefits of cancer in clinical trials; (d) very weak support from proof-of-principle studies; and (e) the inability of vitamin D alone to treat advanced cancers. Addressing these concerns, more potent and less toxic vitamin D analogs have been created, and these are presently undergoing clinical trial evaluation. To provide key information regarding the functions of vitamin D and VDRs, this review provided details of significant advancements in the functional analysis of vitamin D and its analogs and VDR polymorphisms associated with cancers.

Association between Vitamin D Receptor Polymorphism and Susceptibility to Oral Lichen Planus and Oral Squamous Cell Carcinoma

Introduction

Oral squamous cell carcinomas (OSCC) comprise 90-95% of oral cancers. Early diagnosis improved the survival rate of OSCC patients to 80-90%. Oral lichen planus (OLP) is a chorionic inflammatory disease with malignancy potential. The vitamin D receptor (VDR) plays a critical role in the pathogenesis of oral cancer. This study aimed to determine the association between VDR rs7975232 (Apa I) polymorphism and potential susceptibility to OLP and OSCC risks.

Materials and Methods

In this prospective case-control study, a total of 120 blood samples were obtained from OSCC patients (n=29), OLP (n=50), and controls (n=40). VDR rs7975232 polymorphism was studied using the Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR-RFLP) method. Statistical analysis was performed with SPSS Version 23 software. Data were expressed as means ± standard deviation (SD). Age, sex, allelic frequency, and genotyping were compared using the chi-square test. A p-value of less than 0.05 was regarded as statistically significant. The disease risk was estimated by Odds ratio (OR) with a 95% confidence interval.

Results

A significant age difference was observed between the controls and the OSCC group (p=0.001). A significant difference was observed in Aa and aa genotypes compared with AA between OSCCs and controls. Moreover, dominant (p<0.001), additive (p<0.001), and allelic (p=0.001) models were different between groups.

Conclusion

There was a positive association between rs7975232 VDR polymorphism and susceptibility to OSCC. More experimental evidence must reveal the possible association between rs7975232 and the risk of OLP in a larger cohort.

Vitamin D Status, Cdx2 Genotype, and Colorectal Cancer Survival: Population-Based Patient Cohort

According to recent evidence, the prognostic value of Vitamin D (VitD) status for colorectal cancer (CRC) patients might be confined to patients with the GG genotype of Cdx2, a functional polymorphism of the VitD receptor gene. We aimed to validate these findings in a cohort of CRC patients. Post-operative serum 25-hydroxyvitamin D concentration was determined by mass spectrometry and Cdx2 genotyping was performed from blood or buccal swabs using standard methods. Joint associations of VitD status and Cdx2 with overall survival (OS), CRC-specific survival (CSS), recurrence-free survival (RFS), and disease-free survival (DFS) were assessed using Cox regression. For patients with GG genotype, adjusted hazard ratios (95% confidence interval) for the associations of sufficient compared with deficient VitD were 0.63 (0.50-0.78), 0.68 (0.50-0.90), 0.66 (0.51-0.86), and 0.62 (0.50-0.77) for OS, CSS, RFS, and DFS, respectively. These associations were weaker and not statistically significant for the AA/AG genotype. Interaction between VitD status and genotype did not reach statistical significance. VitD deficiency is an independent predictor of poorer survival, particularly for the GG Cdx2 carriers, suggesting a potential role of VitD supplementation according to VitD status and genotype, which should be evaluated in randomised trials.

Associations of vitamin D receptor encoding gene variants with premenopausal breast cancer risk

OBJECTIVE

This study evaluates whether vitamin D receptor (VDR) gene variations are associated with premenopausal breast cancer in Pakistani cohorts.

METHODS

Genomic DNA was isolated from 228 breast cancer patients and 500 non-cancer controls. Six polymorphic variants (rs11568820, rs4516035, rs2228570, rs1544410, rs7975232, rs731236) of the VDR gene were genotyped using PCR-RFLP analysis. All statistical analysis was carried out on IBM-SPSS 23 at p-value <.05. Chi-square test and odds ratios (ORs) along with 95% confidence interval (CIs) were applied to evaluate the relationship between VDR gene polymorphisms and breast cancer.

RESULTS

Results showed that the A/A genotype of EcoRV (OR = 2.125, 95% CI = 1.024 to 4.412) and the A/a genotype of Apa1 (OR = 6.094, 95%CI = 4.111 to 9.033) gene polymorphism had an increased risk of premenopausal breast cancer. No associations of the Bsm1 and Taq1 polymorphisms were observed in premenopausal women. Moreover, the Cdx2 GG (OR = 0.34, 95%CI = 0.192-0.602) genotype had a significant protective effect on breast cancer. However, strong LD was existed between Bsm1/Taq1 (D' = 0.757, CI = 0.67-0.82) and Apa1/Taq1 (D' = 0.695, CI = 0.6-0.77). Haplotype analysis showed no association between premenopausal breast cancer and VDR haplotypes.

CONCLUSION

These analyses indicates that the VDR EcoRV A/A and Apa1 A/a genotypes may be risk factors for breast cancer development among premenopausal women.

The association between vitamin D receptor polymorphism and phases of chronic hepatitis B infection in HBV carriers in Thailand

Vitamin D receptor (VDR) polymorphism partly regulates the immune system and is associated with hepatic flare in chronic Hepatitis B virus infection (HBV). Our study identified the association between two distinct phases, VDR polymorphisms and HBV inactive carrier (IC) and chronic hepatitis (CH). Chronic HBV patients were enrolled from February to August 2020. An HBV viral load (VL) < 2,000 IU/ml twice for 6 months apart, with no prior history of HBV treatment, defined the IC phase. Six common polymorphisms in the VDR gene, including CdX-2, GATA, FokI, Bsml, ApaI, and TaqI, were studied using real-time PCR. The different outcomes in allele, genotype, and haplotype frequencies in between groups and linkage disequilibrium (LD) mapping were analyzed. Among 324 enrolled patients, there were 163 patients in IC and 161 patients in CH phases. The mean vitamin D levels were not statistically different between groups. The proportion of allele frequencies of CdX-2 in IC and CH was 53.7% and 62.7% for G allele, and 46.3% and 37.3% for A allele (p 0.019). The proportion of GG genotype of CdX-2 was less frequently found in patients with IC compared to that in patients with CH (27% vs 41%, p 0.028). By multivariate analysis, CdX-2 G/A genotypes were independently associated with IC, with adjusted odd ratio (OR) 1.83 (1.10-3.04), p 0.019. The LD mapping of single nucleotide polymorphisms (SNP) revealed high LD scores in Bsml/ApaI/TaqI (BAT) haplotype in both groups while, CdX-2/GATA and GATA/FokI demonstrated high LD score only in CH group. CdX-2 G/A genotypes were independently associated with IC status in Thai patients with chronic HBV infection. The difference in LD of the CdX-2/GATA and GATA/FokI haplotypes in between groups may represent a non-random selection resulting in the variation of immune control.

Investigation of Microbial Translocation, TLR and VDR Gene Polymorphisms, and Recurrence Risk in Stage III Colorectal Cancer Patients

Gut microbial dysbiosis and microbial passage into the peripheral blood leads to colorectal cancer (CRC) and disease progression. Toll-like (TLR) and vitamin D (VDR) receptors play important role in the immune modulation and polymorphisms that may increase CRC risk and death rates. The aim of the current study was to demonstrate the prognostic value of microbial DNA fragments in the blood of stage III CRC patients and correlate such microbial detection to TLR/VDR polymorphisms. Peripheral blood was collected from 132 patients for the detection of microbial DNA fragments, and TLR/VDR gene polymorphisms. In the detection of various microbial DNA fragments, TLR and VDR polymorphisms was significantly higher compared to healthy group. Homozygous individuals of either TLR or VDR polymorphisms had significantly higher detection rates of microbial DNA fragments. Mutational and MSI status were significantly correlated with TLR9 and VDR polymorphisms. Significantly shorter disease-free survival was associated with patients with BRAF mutated tumors and ApaI polymorphisms, whereas shorter overall survival was associated with the detection of C. albicans. The detection of B. fragilis, as demonstrated by the multivariate analysis, is an independent poor prognostic factor for shorter disease-free survival. TLR/VDR genetic variants were significantly correlated with the detection of microbial fragments in the blood, and this in turn is significantly associated with tumorigenesis and disease progression.

Assessment the effect of vitamin D supplementation on plasma vitamin D levels, inflammation, and oxidative stress biomarkers based on vitamin D receptor genetic variation in breast cancer survivors: a protocol for clinical trial

BACKGROUND

Both human genes and environmental exposures, due to complex interplay, play important role in the cancer etiology. Vitamin D is associated with a reduced risk of incidence and mortality of several human cancers. This study will aim to investigate the possible effects of individual polymorphisms in vitamin D receptor (VDR) as well as effects of VDR haplotypes on response to vitamin D supplementation in breast cancer survivors.

METHODS

This is an interventional study in which the effects of vitamin D supplementation on plasma vitamin D levels, inflammatory and antioxidant biomarkers and factors associated with cell proliferation, differentiation, damage, and apoptosis will be investigated stratified by variations in VDR genotype. The present study will be conducted on breast cancer survivors referred to the Shohadaye Tajrish hospital and its associated clinics. One hundred ninety-eight breast cancer survivors will receive 4000 IU of vitamin D3 daily for 12 weeks. VDR Fok1, ApaI, TaqI, BsmI, and Cdx-2 genotype will be determined at the end of the study and responses to vitamin D supplements (inflammatory, antioxidant, cell proliferation, differentiation, damage, and apoptosis biomarkers) will be compared between the three subgroups of each VDR polymorphism as well as different VDR haplotype categories.

DISCUSSION

Genetic variation is a fundamental factor influencing individuals' divergent responses to diet, nutritional status, metabolic response, and diet-related health disorders. Furthermore, studies of gene and environment interactions will provide a precise and accurate assessments of individuals' dietary requirements by considering both the genetic and environmental aspects simultaneously. The results of the current study, to some extent, will highlight the discrepancies existing in the findings of different studies regarding vitamin D, VDR, and cancer by considering both the genetic and environmental aspects simultaneously. If responses to vitamin D supplementation could be modified by VDR SNPs, determining the distribution of VDR polymorphisms in both breast cancer survivors and healthy populations will provide a new insight into the vitamin D requirements of individuals to prevent cancer and its related mortality based on their genotypes. Trial registration This trial has been registered on Iranian Registry of Clinical Trials (IRCT) under the identification code: IRCT2017091736244N1, registration date: 2017-11-10, http://www.irct.ir/trial/27153.

The Comparison of 25-Hydroxyvitamin D3 between Patients With and Without Cervical Cancer

BACKGROUND: Vitamin D was currently believed to have effects on numerous cancer pathogenic processes. AIM: This study was to assess the correlation of Vitamin D serum level in women with carcinoma cervix and also evaluate the effect of carcinoma cervix on the Vitamin D serum. METHODS: This was an observational with a cross-sectional study. Participants were women with cervical cancer who have not received any treatment, presented to the Oncology Clinic of the Obstetrics and Gynecology Department of Dr. Hasan Sadikin General Hospital, and women without cervical cancer. The level of Vitamin D3 was analyzed in the Serology Laboratory of Clinical Pathology Department of Dr. Hasan Sadikin General Hospital. RESULTS: There were 113 participants consisted of 58 women with cervical cancer and 55 healthy women. Mean levels of Vitamin D3 were significantly lower in cervical cancer group than non-cervical cancer group (26.74 ± 13.166 vs. 32.16±14.86, p = 0.022). CONCLUSION: The level of Vitamin D3 was found to be significantly higher in the non-cervical cancer group than cervical cancer group.

Interactions Between Vitamin D and Calcium Intake, Vitamin D Receptor Genetic Polymorphisms, and Colorectal Cancer Risk

BACKGROUND

Vitamin D has anticarcinogenic properties and acts through vitamin D receptor (VDR) to carry out its functions.

AIMS

This study explored the independent and combined effects of dietary vitamin D and calcium, and VDR genetic polymorphisms on colorectal cancer risk in a Chinese population.

METHODS

This ongoing case-control study recruited 488 cases with histologically confirmed colorectal cancer and 496 sex- and age-matched controls. Vitamin D and calcium intakes were assessed by a validated food frequency questionnaire, and VDR genotype was conducted for Fok I (rs2228570), Bsm I (rs1544410), Apa I (rs7975232), and Taq I (rs731236). Unconditional logistic regression was used to calculate odds ratio and 95% confidence interval after adjusting for various confounders.

RESULTS

No significant association was found between Fok I, Bsm I, Apa I, Taq I, and colorectal cancer risk. Higher intakes of dietary vitamin D and calcium were associated with 47% and 50% reduction in colorectal cancer risk. Significant interaction was observed between dietary vitamin D intake and Apa I polymorphisms in relation to colorectal cancer risk (P_interaction = 0.006). Subjects with higher dietary vitamin D intake and mutant Apa I A allele had a substantially decreased risk of colorectal cancer compared to Apa I aa carriers with lower vitamin D intake.

CONCLUSIONS

Our study supports that Apa I may interact with dietary vitamin D intake on colorectal cancer risk. However, no interactions were found between dietary vitamin D or calcium intakes and Fok I, Bsm I, and Taq I in relation to colorectal cancer risk.

Association between common variants in vitamin D receptor gene and susceptibility to Non-Hodgkin's lymphoma: a case-control study

Vitamin D (VDR)-mediated signaling contributes to the cell signaling pathways that affect cancer development. This study is conducted on 104 patients diagnosed with non-Hodgkin's lymphoma (NHL) and 246 healthy subjects to investigate the link between five genetic variants spanning the VDR gene and the risk of this malignancy in Iranian subjects. The PCR-RFLP method was used for the analysis of BsmI (rs1544410), ApaI (rs7975232), FokI (rs2228570) and TaqI (rs731236) variants. A simple Tetra-ARMS-PCR technique was employed for the genotyping of the Cdx2 (rs11568820) variant. No significant link was found between both groups regarding ApaI (rs7975232) and FokI (rs2228570) variants (P > 0.05). Also, different genetic models of TaqI (rs731236), BsmI (rs1544410) and Cdx2 (rs11568820) polymorphisms were significantly correlated to decreased risk of NHL (Odd ratios <1). We found three haplotypes were strongly associated with an increased risk of NHL (P < 0.0001). Linkage-disequilibrium (LD) analysis showed a strong linkage between TaqI (rs731236) and BsmI (rs1544410) among NHL case and control subjects. Our findings indicated that functional variants of the VDR gene are linked to a decreased risk of NHL in our population. Further replication studies in different ethnic groups are needed to validate our results.

Vitamin D Receptor (VDR) Gene Polymorphism in Patients Diagnosed with Colorectal Cancer

Colorectal cancer (CRC) is one of the most commonly occurring neoplasias in humans. The prevalence of CRC rates is still rising. Although the exact background of the disease still remains unknown, it is believed that CRC may not only be a result of environmental factors, but also genetic ones. One of the mechanisms underlying CRC might be the vitamin D pathway, as CRC is the most closely linked neoplasia to vitamin D deficiency. This study shows a possible association of the vitamin D receptor (VDR) polymorphisms FokI, BsmI, ApaI, and TaqI with CRC susceptibility. A total of 103 patients diagnosed with CRC (61 men and 42 women, aged 57-82 years) and 109 healthy people (50 men and 59 women, aged 47-68 years) were genotyped using PCR-RFLP for FokI, BsmI, ApaI, and TaqI. None of the single nucleotide polymorphisms (SNPs) individually increased or decreased the risk of CRC. The evaluation of haplotypes revealed two that might enhance the likelihood of CRC development: taB (OR = 30.22; 95% CI 2.81-325.31; p = 0.01) and tAb (OR = 3.84; 95% CI 1.29-11.38; p = 0.01). In conclusion, genotyping is an easy and robust procedure that needs to be performed only once in a lifetime. A creation of a relevant SNP's panel might contribute to the identification of the groups that are at the greatest risk of CRC.

Association of Vitamin D Receptor Polymorphisms (FokI (Rs2228570), ApaI (Rs7975232), BsmI (Rs1544410), and TaqI (Rs731236)) with Gastric Cancer in a Kurdish Population from West of Iran

Background

The association of 1,25-dihydroxy vitamin D3 (1,25(OH)2D3) and its receptor, vitamin D receptor (VDR), with cancer types have been studied. However, there are controversial findings regarding the association of specific VDR polymorphisms with different kinds of cancers. In the current study, we investigated the association of VDR polymorphisms (Fok1 (rs2228570), ApaI (rs7975232), BsmI (rs1544410), and TaqI (rs731236)) with the risk of gastric cancer in a Kurdish population of Kermanshah in Iran for the first time.

Methods

In this case-control study, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used in 99 gastric cancer patients and 100 healthy subjects as controls.

Results

The frequencies of f (FokI), b (BsmI), t (TaqI), and a (ApaI) alleles were: 55.6%, 27.3%, 62.1%, and 44.95% in the patient group, respectively and 42%, 29.5%, 54.5%, and 46.0% in the control group, respectively. Analysis of the results indicated that there was a positive association between the frequency of FokI genotypes with gastric cancer risk (p= 0.021). However, no statistically significant association of BsmI, Taq1, and ApaI polymorphisms of VDR was detected in gastric patients when compared with healthy individuals.

Conclusion

VDR-FokI polymorphism could increase the risk of GC development and predispose to the disease by mechanisms.

Ethnicity as modifier of risk for Vitamin D receptors polymorphisms: Comprehensive meta-analysis of all cancer sites

Vitamin D receptors polymorphisms are found to be associated with several cancers. Since their prevalence vary across ethnicities and ethnicity itself seems to influence the cancer risk, a comprehensive meta-analysis was performed to investigate the role of VDR Fok1, Bsm1, Taq1, Apa1, Cdx2 and cancer risk at specific organ sites. Odds ratios, calculated with random-effects models, summarized one-hundred-ninety-two independent studies for twenty-two cancer sites. Evidence was provided that Fok1, Bsm1, Cdx2, Apa1 and Taq1 are linked to cancer susceptibility for colorectal, lung, ovarian, skin, multiple myeloma and brain cancer. Stratifying by ethnicity, some differences were found, partially explained by minor allele frequency (MAF), for colorectal cancer, ovarian and prostate cancer in Caucasian and prostate cancer in Asian populations. In summary, ethnicity may be a modifier of cancer risk, in particular for hormone dependent cancers and it should be considered evaluating the effect of VDR on cancer risk.

Genetic Polymorphisms of Vitamin D Receptor Gene are Associated with Cervical Cancer Risk in Northeastern Thailand

OBJECTIVE

This study aimed to explore whether VDR polymorphisms (Fok1, Apa1 and Taq1) are associated to the cervical cancer in Thai population.

MATERIALS AND METHODS

Subjects of 204 cervical cancer patient and 204 age-matched healthy control were enrolled in the case-control study. VDR polymorphisms were detected by using real-time PCR. Haplotype analysis of three loci was applied to the obtained genotypes.

RESULTS

Significantly increased risk for cervical cancer was observed in carriers of TT genotype (p = 0.0388) and T allele (p = 0.0357) of Fok1 and TC genotype (p = 0.0001), CC genotype (p = 0.0160) and the C allele of Taq1 (p = 0.0001). Haplotype analyses revealed a significant correlation between C-T-C, T-G-C and T-T-C haplotypes and elevated risk for cervical cancer (OR = 2.06; 95%CI = 1.06-4.00; p = 0.0313, OR = 2.15; 95%CI = 1.22-3.80; p = 0.0078 and OR = 2.81; 95%CI = 1.53-5.16; p = 0.0006, respectively). Furthermore, haplotype carrying C allele of Taq1 (C-G-C + C-T-C + T-G-C + T-T-C) significantly increased cervical cancer risk with OR of 1.92 (95%CI = 1.32-2.79, p = 0.0006).

CONCLUSION

Our finding revealed an association between VDR polymorphisms and cervical cancer risk. Taq1 C allele might be a molecular marker for cervical cancer development.<br />.

Vitamin D Receptor Polymorphisms and Cancer

Increasing scientific evidence supports the link between vitamin D and cancer risk. The active metabolite 1,25(OH)2D exerts its activity by binding to the vitamin D receptor (VDR), an intracellular receptor that mediates transcriptional activation and repression of target genes. The binding of 1,25(OH)2D to VDR is able to regulate hundreds of different genes. VDR is active in virtually all tissues including the colon, breast, lung, ovary, bone, kidney, parathyroid gland, pancreatic b-cells, monocytes, T lymphocytes, melanocytes, keratinocytes, and also cancer cells.The relevance of VDR gene restriction fragment length polymorphisms for various types of cancer has been investigated by a great number of studies.We have carried out a systematic review of the literature to analyze the relevance of more VDR polymorphisms (Fok1, Bsm1, Taq1, Apa1, and Cdx2) for individual malignancies considering ethnicity as a key factor for heterogeneity.Up to December 2018, we identified 176 independent studies with data to assess the risk of breast, prostate, colorectal, skin (melanoma and non-melanoma skin cancer), lung, ovarian, kidney, bladder, gallbladder, esophageal, thyroid, head and neck, liver and pancreatic cancer, oral squamous cell carcinoma, non-Hodgkin lymphoma, multiple myeloma and sarcoma.Significant associations with VDR polymorphisms have been reported for prostate (Fok1, Bsm1, Taq1, Apa1, Cdx2), breast (Fok1, Bsm1, Taq1, Apa1, CdX2), colorectal (Fok1, Bsm1, Taq1, Apa1), and skin cancer (Fok1, Bsm1, Taq1). Very few studies reported risk estimates for the other cancer sites.Conflicting data have been reported for most malignancies, and at present, it is still not possible to make any definitive statements about the importance of the VDR genotype for cancer risk. It seems probable that other factors such as ethnicity, phenotype, 25(OH)D plasma levels, and UV radiation exposure play a role as confounding factors and introduce heterogeneity.To conclude, there is some indication that VDR polymorphisms may modulate the risk of some cancer sites and in future studies VDR genetic variation should be integrated also with assessment of vitamin D status and stratified by ethnicity.

The Role of Vitamin D Receptor Gene Polymorphisms in Colorectal Cancer Risk

Vitamin D deficiency has been associated with increased colorectal cancer (CRC) incidence risk and mortality. Vitamin D mediates its action through the binding of the vitamin D receptor (VDR), and polymorphisms of the VDR might explain these inverse associations. The aim of the study was the investigation of the relevance of rs731236; Thermus aquaticus I (TaqI), rs7975232; Acetobacter pasteurianus sub. pasteurianus I (ApaI), rs2228570; Flavobacterium okeanokoites I (FokI) and rs1544410, Bacillus stearothermophilus I (BsmI) polymorphisms of the VDR gene to colorectal carcinogenesis (CRC) and progression. Peripheral blood was obtained from 397 patients with early operable stage II/III (n = 202) and stage IV (n = 195) CRC. Moreover, samples from 100 healthy donors and 40 patients with adenomatous polyps were also included as control groups. Genotyping in the samples from patients and controls was performed using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). A significant association was revealed between all four polymorphisms and cancer. Individuals with homozygous mutant (tt, aa, ff or bb) genotypes were more susceptible to the disease (p < 0.001). All of the mutant genotypes detected were also significantly associated with stage IV (p < 0.001), leading to significantly decreased survival (p < 0.001). Moreover, all four polymorphisms were significantly associated with KRAS (Kirsten ras oncogene) mutations and Toll-like receptor (TLR2, TLR4 and TLR9) genetic variants. In multivariate analysis, tt, aa and ff genotypes emerged as independent factors associated with decreased overall survival (OS) (p = 0.001, p < 0.001 and p = 0.001, respectively). The detection of higher frequencies of the VDR polymorphisms in CRC patients highlights the role of these polymorphisms in cancer development and progression.

Decreased vitamin D receptor protein expression is associated with progression and poor prognosis of colorectal cancer patients

This study aimed to investigate vitamin D receptor (VDR) expression levels and evaluate their clinical significance in patients with colorectal cancer (CRC). VDR protein expression was validated by immunohistochemistry in 188 CRC tissues and 134 normal colorectal tissues. The associations between VDR expression and clinicopathologic characteristics, including prognostic outcomes, were analyzed. VDR expression in normal colorectal tissue was higher than that in CRC (83.6% versus 34.6%, P = 4.489 × 10^-20) and generated moderate diagnostic performance for CRC detection (AUC = 0.88, sensitivity = 0.87, specificity = 0.84). Low VDR expression was associated with invasion depth (P = 0.001) and poor survival in CRC (P = 0.031). Univariate Cox analysis demonstrated VDR expression (P = 0.036) was a significant prognostic predictor for survival in patients with CRC. Low VDR expression could be a valuable diagnostic and prognostic biomarker for CRC patients. Targeting VDR may offer a potential therapeutic strategy for blocking CRC.

Vitamin D receptor ApaI polymorphism associated with progression of liver disease in Vietnamese patients chronically infected with hepatitis B virus

Background

Vitamin D derivatives and their receptor (VDR) are potent modulators of immune responses in various diseases including malignancies as well as in metabolic and infectious disorders. The impact of vitamin D receptor polymorphisms on clinical outcomes of hepatitis B virus (HBV) infection is not well understood. This study aims to investigate the potential role of VDR polymorphisms (TaqI, FokI, ApaI, and BsmI) in Vietnamese HBV infected patients and to correlate these polymorphisms with the progression of HBV-related liver disease.

Methods

Four hundred forty-three HBV infected patients of the three clinically well-defined subgroups chronic hepatitis B (CHB, n = 183), liver cirrhosis (LC, n = 89) and hepatocellular carcinoma (HCC, n = 171) and 238 healthy individuals (HC) were enrolled. VDR polymorphisms were genotyped by DNA sequencing and in-house validated ARMS assays. Logistic regression models were applied in order to determine the association of VDR polymorphisms with manifest HBV infection as well as with progression of related liver diseases mulin different genetic models.

Results

The VDR ApaI CA genotype was less frequent in HCC than in CHB patients in different genetic models (codominant model, OR = 0.5, 95%CI = 0.3–0.84, P = 0.004; dominant model, OR = 0.46, 95%CI = 0.27–0.76, P = 0.0023). In the recessive model, the genotype ApaI AA was found more frequently among HCC compared to CHB patients (OR = 2.56, 95%CI = 1.01–6.48, P = 0.04). Similarly, the ApaI CA genotype was less frequent in HCC than in non-HCC group codominant model, OR = 0.6, 95%CI = 0.4–0.98, dominant model, P = 0.04 and OR = 0.6, 95%CI = 0.38–0.90, P = 0.017). The ApaI genotypes CA and AA was significantly associated with higher levels of liver enzymes, bilirubin, and HBV DNA (P < 0.05). No association between TaqI, FokI and BsmI polymorphisms and any clinical outcome as well as liver disease progression was found.

Conclusions

Among the four investigated VDR polymorphisms, ApaI is associated with clinical outcome and liver disease progression in Vietnamese HBV infected patients.

MicroRNA-binding site polymorphisms and risk of colorectal cancer: A systematic review and meta-analysis

Genetic variations in miRNAs binding site might participate in cancer risk. This study aimed to systematically review the association between miRNA-binding site polymorphisms and colorectal cancer (CRC). Electronic literature search was carried out on PubMed, Web of Science (WOS), Scopus, and Embase. All types of observational studies till 30 November 2018 were included. Overall 85 studies (21 SNPs) from two systematic searches were included analysis. The results showed that in the Middle East population, the minor allele of rs731236 was associated with decreased risk of CRC (heterozygote model: 0.76 [0.61-0.95]). The minor allele of rs3025039 was related to increased risk of CRC in East Asian population (allelic model: 1.25 [1.01-1.54]). Results for rs3212986 were significant in overall and subgroup analysis (P < .05). For rs1801157 in subgroup analysis the association was significant in Asian populations (including allelic model: 2.28 [1.11-4.69]). For rs712, subgroup analysis revealed a significant (allelic model: 1.41 [1.23-1.61]) and borderline (allelic model: 0.92 [0.84-1.00]) association in Chinese and Czech populations, respectively. The minor allele of rs17281995 increased risk of CRC in different genetic models (P < .05). Finally, rs5275, rs4648298, and rs61764370 did not show significant associations. In conclusion, minor allele of rs3025039, rs3212986, and rs712 polymorphisms increases the risk of CRC in the East Asian population, and heterozygote model of rs731236 polymorphism shows protective effect in the Middle East population. In Europeans, the minor allele of rs17281995 may increase the risk of CRC, while rs712 may have a protective effect. Further analysis based on population stratifications should be considered in future studies.

Association of select vitamin D receptor gene polymorphisms with the risk of tobacco-related cancers - a meta-analysis

The observed increase in morbidity and mortality due to tobacco-related cancers, especially those in the respiratory system and esophagus, is becoming a public health challenge. Smoking cigarettes is one of the main risk factors predisposing individuals to many types of cancers. The aim of this study was to determine the role of select vitamin D receptor (VDR) gene polymorphisms as risk factors in tobacco-related cancers. The MEDLINE and ResearchGate databases were used to search for articles up to June 2017, and 12 articles including 26 studies concerning FokI, ApaI, TaqI and BsmI polymorphisms and lung, neck, head, esophageal and oral cancers were chosen. In total, 5 113 cases and 5 657 controls were included in the pooled analysis. We found a significant relationship between tobacco-related cancers and the occurrence of the "t" allele in the TaqI polymorphism of VDR. The occurrence of the "t" allele reduced the risk of tobacco-related cancers by 17% (OR = 0.83, 0.72-0.96 95% CI, p-value = 0.0114). Our analysis revealed that there is a correlation between the TaqI polymorphism of VDR and the risk of tobacco-related cancers.

Vitamin D receptor gene polymorphisms affecting changes in visceral fat, waist circumference and lipid profile in breast cancer survivors supplemented with vitamin D3

OBJECTIVE

We investigated whether vitamin D receptor (VDR) polymorphisms are associated with circulating metabolic biomarkers and anthropometric measures changes in breast cancer survivors supplemented with vitamin D3.

METHODS

One hundred sixty-eight breast cancer survivors admitted to Shohaday-e-Tajrish hospital received 4000 IU of daily vitamin D3 supplements for 12 weeks. Anthropometric measurements as well dietary, physical activity and plasma metabolic biomarkers assessments were performed before and after intervention. VDR polymorphisms were considered as the main exposures. Multivariate multiple linear regression analyses were used to determine the association between the VDR single-nucleotide polymorphisms (SNPs) and changes in metabolic and anthropometric measures in response to vitamin D3 supplementation.

RESULTS

One hundred twenty-five (85%) women had insufficient and inadequate levels of plasma 25-hydroxy vitamin D (25(OH)D) at baseline. Compared to the AA genotype of the ApaI, the aa category showed greater increase in muscle mass [71.3(10.7131.9)] and higher decrease in LDL-C [- 17.9(- 33.6, - 2.3)] levels after adjustment for potential confounders. In addition, the heterozygous genotype (Bb) of the BsmI VDR was associated with higher increase in WC following vitamin D3 supplementation, compared to BB [2.7(0.1,5.3)]. Haplotype score analyses indicate a significant association between inferred haplotypes from BsmI, ApaI, TaqI and FokI, BsmI and Cdx2 VDR polymorphisms and on-study visceral fat changes.

CONCLUSIONS

Findings of this study showed that genetic variation in the VDR gene was associated with changes in cardio-metabolic parameters in breast cancer survivors, supplemented with vitamin D3, results could provide a novel insight into better understanding of which subset of individuals benefit most from normalization of vitamin D status.

TRIAL REGISTRATION

This trial has been registered on the Iranian Registry of Clinical Trials (IRCT) under the identification code: IRCT2017091736244N1, registration date: 2017-11-10, http://www.irct.ir/trial/27153 and was approved by the ethics committees of the National Nutrition and Food Technology Research Institute (NNFTRI), Shahid Beheshti University of Medical Sciences (SBMU).

Current evidence for vitamin D in intestinal function and disease

Vitamin D activity is associated with the modulation of a wide variety of biological systems, in addition to its roles in calcium homeostatic mechanisms. While vitamin D is well known to promote gastrointestinal calcium absorption, vitamin D also plays a role in attenuating and/or preventing the progression of several gastrointestinal diseases including Crohn’s disease, ulcerative colitis, and colorectal cancer, and may also play a role in chemotherapy-induced intestinal mucositis. The pro-differentiation, immunomodulatory, and anti-inflammatory effects of vitamin D, which has been reported in numerous circumstances, are key potential mechanisms of action in the prevention of gastrointestinal disorders. While the debate of the effectiveness of vitamin D to treat bone pathologies continues, the clinical importance of vitamin D therapy to prevent gastrointestinal disorders should be investigated given current evidence, using both nutritional and pharmaceutical intervention approaches.

Impact statement

The non-skeletal functions of vitamin D play an important role in health and disease. The anti-inflammatory properties and maintenance of intestinal function fulfilled by vitamin D impact other systems in the body though downstream processing. This review provides insight into the mechanisms underpinning the potential benefits of vitamin D in both maintaining intestinal homeostasis and associated diseased states.

Association of vitamin D receptor gene polymorphisms with osteosarcoma risk and prognosis

OBJECTIVE

Through its receptor (VDR), vitamin D3 plays an important role in a wide variety of cellular processes. Polymorphisms in VDR gene have been linked to risk of various cancers and their prognoses. We conducted a case-control study to analyze he relationship of VDR gene polymorphisms with the occurrence and prognosis of osteosarcoma.

METHODS

Fifty-eight osteosarcoma patients and 75 healthy controls were included in the study. Single nucleotide change polymorphisms (SNPs) in Cdx2, FokI, BsmI, ApaI and TaqI regions of VDR gene were examined with SNaPshot mini-sequencing technique. Allele and genotype frequencies in patients and controls were compared. The association of polymorphic genotypes with osteosarcoma was evaluated. The relationship of the presence of polymorphism to prognostic parameters and survival rates were also analyzed.

RESULTS

Allele and genotype frequencies of Cdx2, FokI, BsmI, ApaI and TaqI regions in VDR gene were found to be similar in patients and controls. Polymorphisms in these regions were not associated with osteosarcoma risk. In patients having Cdx2 polymorphic allele, tumor volume was greater (p:0.041), metastasis was more common (p:0.042) and histopathological response to chemotherapy was worse (p:0.044). Good histopathological response was significantly higher in patients with BsmI homozygous polymorphism (p:0.037). In the presence of heterozygous Cdx2 and homozygous a higher three-year overall survival rate was found, while there was a higher event-free survival rate in patients with ApaI polymorphisms.

CONCLUSION

Our results suggested that although polymorphisms of VDR gene are not related to the development of osteosarcoma, they may be important for prognosis. Understanding the effect of VDR polymorphisms on osteosarcoma will be important in identifying new prognostic parameters and new targets for treatment.

VDR gene FokI polymorphism as a poor prognostic factor for papillary thyroid cancer

This is the first study to investigate the effect of vitamin D receptor ( VDR) gene single-nucleotide polymorphisms on the clinicopathologic features of papillary thyroid cancer in Turkey. A total of 165 patients with papillary thyroid cancer and 172 controls were included in this case-control study. VDR gene single-nucleotide polymorphisms FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) were evaluated using reverse-transcription polymerase chain reaction. VDR gene polymorphisms BsmI, ApaI, and TaqI did not differ between the papillary thyroid cancer group and control group (p > 0.05, each). BsmI, ApaI, and TaqI were not associated with papillary thyroid cancer risk. The VDR gene FokI CT/TT genotype was associated with an increased papillary thyroid cancer risk (CT vs CC: odds ratio = 1.71, 95% confidence interval = 1.15-2.76, p = 0.028; TT vs CC: odds ratio = 2.44, 95% confidence interval = 1.29-4.62, p = 0.005; CT/TT vs CC: odds ratio = 1.88, 95% confidence interval = 1.20-2.96, p = 0.006; CT/CC vs TT: odds ratio = 1.80, 95% confidence interval = 1.05-3.20, p = 0.041). VDR gene polymorphisms were not in linkage disequilibrium. The FokI TT genotype was associated with having T3 and T4, stage III/IV, extra-thyroidal invasion. The FokI CT/TT or TT genotype was associated with developing N1 status, multifocality, tumor size ≥10 mm, and treatment with radioiodine therapy. Persistence/recurrence did not differ between the FokI genotypes. Carriers of the FokI T allele were at an increased risk of more advanced tumor-node-metastasis stage, greater tumor size, multifocality, and extra-thyroidal invasion of papillary thyroid cancer compared with the CC genotype. VDR gene FokI T allele and TT genotype correlated with aggressiveness of papillary thyroid cancer; thus, FokI could be useful as a poor prognostic factor to assess the high risk of papillary thyroid cancer.

Positive correlation between vitamin D receptor gene FokI polymorphism and colorectal cancer susceptibility in South-Khorasan of Iran

Colorectal cancer (CRC) is a global public health problem. Despite the major milestone in early diagnosis and treatment of colorectal cancer, the prevalence of CRC rates is still rising. The etiology of CRC is still unknown but we know CRC is influenced by both of environment and genetic factors. In this study, we aimed to elucidate the role of vitamin D receptor gene polymorphic regions; FokI and TaqI single nucleotide polymorphisms, in increasing the risk of colorectal cancer in Birjand population. One hundred patients with CRC and 100 healthy controls recruited to the study. Genotyping was performed by PCR-RFLP (restriction fragment length polymorphism) method technique for all individuals. There were statistically significant differences between ff genotype and f allele of FokI SNP in case and control groups. Our results manifested positive correlation between ff genotype and f allele of FokI SNP with colorectal cancer predisposition (P = 0.035, P = 0.0001 respectively) in South Khorasan population. The present study showed that FokI polymorphism but not TaqI polymorphism may contribute to CRC susceptibility. In addition, ff genotype of FokI polymorphism was associated with CRC risk.

Correlation between Vitamin D3 level and extrahepatic manifestation in chronic hepatitis type-C virus patients

Background

Chronic hepatitis type-C virus (HCV) infection is one of the most common worldwide viral disorders, which leads to various clinical complications as well as extrahepatic manifestations. Furthermore, Vitamin D3 has also been reported to have relationship with the mentioned complications. The aim is to evaluate the correlation between Vitamin D3 level and extrahepatic manifestation in chronic HCV patients.

Materials and Methods

This cross-sectional study has been carried out on 90 patients with chronic hepatitis C. The level of Vitamin D3 was assessed in plasma of 90 patients with chronic HCV. Genotyping was done and clinical and sign and symptoms of recruited patients were gathered. Extrahepatic manifestations were evaluated and the correlation of blood, hepatic, and immunological factors and the level of Vitamin D3 were assessed.

Results

Most of our patients were male (92% vs. 8%). Twenty-nine percent had the insufficient amount of Vitamin D3 (21-30 ng/ml), and the remains had the Vitamin D3 level between 13-20 ng/ml. Furthermore, our assessment demonstrated that deficiency of Vitamin D3 was associated with the extrahepatic manifestations such as purpura (odds radio [OR] [95% confidence interval (CI) 95%] = 8.80 [1.74-44.47], P = 0.004), vasculitis (OR [95% CI] = 11.70 [3.01-45.41], P < 0.001), arthralgia (OR [95% CI] = 20.26 [4.21-97.47], P < 0.001), myalgia (OR [95% CI] = 4.00 [1.01-17.27], P = 0.048), and glomerulonephritis (P = 0.021).

Conclusion

According to our results, the extrahepatic manifestation in the patients with sufficient levels of Vitamin D3 would be less possible. In fact, it could be stated that deficiency in the Vitamin D3 can have a significant relationship with these manifestations.

Vitamin D and Cancer Risk and Mortality: State of the Science, Gaps, and Challenges

There has been substantial enthusiasm recently regarding the potential role of vitamin D in the primary and secondary prevention of cancer. Laboratory studies demonstrate a range of anticarcinogenic effects for vitamin D compounds, but human studies have yielded little consistent evidence supporting a protective association. Higher circulating levels of vitamin D (i.e., 25-hydroxyvitamin D or 25(OH)D) appear to be associated with reduced risk of colorectal and bladder malignancies, but higher risk of prostate and possibly pancreatic cancers, with no clear association for most other organ sites examined. Despite there being no official institutional recommendations regarding the use of vitamin D supplements for cancer prevention, screenings for vitamin D deficiency and vitamin D supplement use have increased substantially over the past decade. These widespread practices demonstrate that population sociobehavioral changes are often adopted before scientifically well-informed policies and recommendations are available. This review critically examines the currently available epidemiologic literature regarding the associations between circulating 25(OH)D, vitamin D supplementation, and vitamin D-related genetic variation and cancer risk and mortality, with a particular emphasis on prospective studies. We identify several important gaps in our scientific knowledge that should be addressed in order to provide sufficient reproducible data to inform evidence-based recommendations related to optimal 25(OH)D concentrations (and any role for vitamin D supplementation) for the primary and secondary prevention of cancer. With few exceptions, such recommendations cannot be made at this time.

Association between vitamin D receptor polymorphisms and hepatitis B virus infection susceptibility: A meta-analysis study

BACKGROUND

Hepatitis B virus (HBV) infection is still a serious public health problem. Understanding risk factors associated with development of HBV is greatly important. Numerous studies focus on relationship between vitamin D receptor (VDR) polymorphisms (TaqI, FokI, ApaI, BsmI) and the risk of HBV infection in different ethnic groups. However the results published so far are inconsistent. The aim of this study is to quantify the association between VDR polymorphisms with HBV infection by meta-analysis approach.

METHODS

A systematic search was performed in Pubmed, Embase, China National Knowledge Infrastructure (CNKI), Database of Chinese Scientific and Technical Periodicals (VIP), and WANFANG. All the relevant studies were published up to October 2016.

RESULTS

Finally, 15 published studies included 4218 cases and 2298 controls were included in this meta-analysis. It is interesting to note that FokI FF tends to be a risk factor for HBV infection [FF vs. ff: P<0.01, OR (95%CI)=1.54 (1.19-2.00), I²=0.0%], with no heterogeneity. In addition, genotype Ff and allele F could increase HBV infection risk [Ff vs. ff: P<0.01, OR (95%CI)=1.39 (1.13-1.72); F vs. f: P=0.02, OR (95%CI)=1.23(1.04-1.45)]. However, no associations were found about VDR TaqI, ApaI and BsmI polymorphisms with HBV infection based on each comparison model.

CONCLUSION

This meta-analysis indicates that FokI genotype FF, Ff and allele F increase the risk of HBV infection. All these results support the notion that VDR FokI genotype might has potential role in HBV susceptibility.

Association between Vitamin D receptor (Cdx2, Fok1, Bsm1, Apa1, Bgl1, Taq1, and Poly (A)) gene polymorphism and breast cancer: A systematic review and meta-analysis

The purpose of this systemic review and meta-analysis was to examine the relationship between VDR gene polymorphisms and breast cancer. Literature was searched through PubMed database, Google scholar, and the web of knowledge from December 2015 to January 2017 and consists of 34 studies (26,372 cases and 32,883 controls). All statistical measures were done using STATA version 11.2. The heterogeneity among studies was tested using I² statistics. Mantel-Haenszel method and DerSimonian-Laird method were used to combine data from studies using both random-effect model and fixed-effect model, respectively. Potential publication bias was evaluated by Egger's test. Sensitivity analysis was also performed to evaluate the quality and consistency in results. The results of this meta-analysis revealed that VDR gene polymorphisms (Bsm1 bb vs BB; SOR = 1.18, 95% CI = 1.054-1.322, Apa1 aa vs AA; SOR = 1.18, 95% CI = 0.87-1.59, Poly (A) LL vs SS; SOR = 1.41, 95% CI = 1.06-1.88, Fok1 ff + Ff vs FF; SOR = 1.25, 95% CI = 0.896-1.759, Apa1 aa+Aa vs AA; SOR = 1.13, 95% CI = 0.95-1.35, Poly (A) LL + LS vs SS; SOR = 1.19, 95% CI = 1.00-1.43, Poly (A) L vs S; SOR = 1.18, 95% CI = 1.03-1.35) are associated with the breast cancer. Cdx2, Bgl1, and Taq1 do not show association with breast cancer. Thus, the finding of this meta-analysis concluded that VDR Bsm1, Apa1, Fok1, and Poly (A) gene polymorphisms may be susceptible for breast cancer development.

The endocrine vitamin D system in the gut

The active vitamin D metabolite 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) has important regulatory actions in the gut through endocrine and probably also intracrine, autocrine and paracrine mechanisms. By activating the vitamin D receptor (VDR), which is expressed at a high level in the small intestine and colon, 1,25(OH)₂D₃ regulates numerous genes that control gut physiology and homeostasis. 1,25(OH)₂D₃ is a major responsible for epithelial barrier function and calcium and phosphate absorption, and the host's defense against pathogens and the inflammatory response by several types of secretory and immune cells. Moreover, recent data suggest that 1,25(OH)₂D₃ has a regulatory effect on the gut microbiota and stromal fibroblasts. Many studies have linked vitamin D deficiency to inflammatory bowel diseases (ulcerative colitis and Crohn's disease) and to an increased risk of colorectal cancer, and the possible use of VDR agonists to prevent or treat these diseases is receiving increasing interest.

Vitamin D receptor polymorphisms or serum levels as key drivers of breast cancer development? The question of the vitamin D pathway

As total vitamin D levels are often lower in black than in white Americans, the former are frequently classified as vitamin D-deficient. To fully understand African vitamin D (25(OH)D) status, other factors should be considered, e.g. vitamin D blood carrier, vitamin D-binding protein (DBP), vitamin D receptor (VDR) and DBP polymorphisms. A prospective study on an indigenous black Tanzanian and a Caucasian Italian population was performed on 50 healthy donors from both populations and 35 Caucasian and 18 African breast cancer patients. 25(OH)D and DBP serum levels were analyzed by ELISA. A1012G, Cdx2 and Fok1 VDR polymorphisms and DBP polymorphisms rs4588 and rs7041 were genotyped by real-time PCR. Vitamin D and DBP levels were lower in healthy African donors than in Caucasians. Africans had a significantly higher frequency of AA and CC for Cdx2 and Fok1 polymorphisms, respectively. These allelic variants were related to a higher transcription of VDR gene and a higher activity of VDR receptor. With regard to polymorphism distribution, Africans showed innate higher levels and activity of VDR. We conclude that a strengthening of the vitamin D pathway could have a protective role against the development of breast cancer in the African population.

Correlation between polymorphism of vitamin D receptor TaqI and susceptibility to colorectal cancer: A meta-analysis

The meta-analysis aimed to investigate the correlation between the polymorphism of the vitamin D receptor (VDR) TaqI and susceptibility of colorectal cancer.Studies were extracted from the electronic databases of PubMed and Embase. The balance of heredity was estimated by the Hardy-Weinberg equilibrium test, and heterogeneity was assessed by Cochran Q statistics and I test. Four assessed models, namely additive (t vs T), dominant (Tt + tt vs TT), recessive (tt vs Tt + TT), and codominant (Tt vs TT and tt vs TT), were used to evaluate the correlations and the effective results were measured as odds ratio (OR) with 95% confidence interval (CI).A total of 14 studies, including 4632 patients and 5086 controls, were enrolled in this meta-analysis. With no significant heterogeneities observed among the 4 models, the fixed-effect model was used to examine the pooled effect value. There were no significant differences among t vs T (OR = 1.01; 95% CI, 0.94-1.09; P = .70), Tt + tt vs TT (OR = 1.05; 95% CI, 0.96-1.15; P = .32), tt vs Tt + TT (OR = 1.01; 95% CI, 0.87-1.17; P = .92), Tt vs TT (OR = 1.03; 95% CI, 0.93-1.13; P = .62), and tt vs TT (OR = 1.00; 95% CI, 0.85-1.17; P = .98) with respect to increasing CRC frequency.No evidence showed that TaqI polymorphisms were significantly associated with susceptibility to CRC.

Vitamin D and colorectal cancer: molecular, epidemiological and clinical evidence

In many cells throughout the body, vitamin D is converted into its active form calcitriol and binds to the vitamin D receptor (VDR), which functions as a transcription factor to regulate various biological processes including cellular differentiation and immune response. Vitamin D-metabolising enzymes (including CYP24A1 and CYP27B1) and VDR play major roles in exerting and regulating the effects of vitamin D. Preclinical and epidemiological studies have provided evidence for anti-cancer effects of vitamin D (particularly against colorectal cancer), although clinical trials have yet to prove its benefit. In addition, molecular pathological epidemiology research can provide insights into the interaction of vitamin D with tumour molecular and immunity status. Other future research directions include genome-wide research on VDR transcriptional targets, gene-environment interaction analyses and clinical trials on vitamin D efficacy in colorectal cancer patients. In this study, we review the literature on vitamin D and colorectal cancer from both mechanistic and population studies and discuss the links and controversies within and between the two parts of evidence.

The impact of vitamin D pathway genetic variation and circulating 25-hydroxyvitamin D on cancer outcome: systematic review and meta-analysis

BACKGROUND

Vitamin D has been linked with improved cancer outcome. This systematic review and meta-analysis investigates the relationship between cancer outcomes and both vitamin D-related genetic variation and circulating 25-hydroxyvitamin D (25OHD) concentration.

METHODS

A systematic review and meta-analysis of papers until November 2016 on PubMed, EMBASE and Web of Science pertaining to association between circulating vitamin D level, functionally relevant vitamin D receptor genetic variants and variants within vitamin D pathway genes and cancer survival or disease progression was performed.

RESULTS

A total of 44 165 cases from 64 studies were included in meta-analyses. Higher 25OHD was associated with better overall survival (hazard ratio (HR=0.74, 95% CI: 0.66-0.82) and progression-free survival (HR=0.84, 95% CI: 0.77-0.91). The rs1544410 (BsmI) variant was associated with overall survival (HR=1.40, 95% CI: 1.05-1.75) and rs7975232 (ApaI) with progression-free survival (HR=1.29, 95% CI: 1.02-1.56). The rs2228570 (FokI) variant was associated with overall survival in lung cancer patients (HR=1.29, 95% CI: 1.0-1.57), with a suggestive association across all cancers (HR=1.26, 95% CI: 0.96-1.56).

CONCLUSIONS

Higher 25OHD concentration is associated with better cancer outcome, and the observed association of functional variants in vitamin D pathway genes with outcome supports a causal link. This analysis provides powerful background rationale to instigate clinical trials to investigate the potential beneficial effect of vitamin D in the context of stratification by genotype.

Association of Vitamin D Receptor Gene Polymorphisms with Colorectal Cancer in a Saudi Arabian Population

BACKGROUND

Vitamin D, causally implicated in bone diseases and human malignancies, exerts its effects through binding to the vitamin D receptor (VDR). VDR is a transcription factor modulating the expression of several genes in different pathways. Genetic variants in the VDR gene have been associated with several cancers in different population including colorectal cancer.

OBJECTIVE

To assess the association of VDR gene polymorphisms in relation with colorectal cancer (CRC) in a Saudi population.

METHODS

The polymorphisms of VDR gene (BsmI, FokI, ApaI and TaqI) were analyzed by the polymerase chain reaction amplification of segments of interest followed by Sanger sequencing. One hundred diagnosed CRC patients and 100 healthy control subjects that were age and gender matched were recruited.

RESULTS

We did not observe significant association of any of the four VDR polymorphisms with colorectal cancer risk in the overall analysis. Although not statistically significant, the AA genotype of BsmI conferred about two-fold protection against CRCs compared to the GG genotype. Stratification of the study subjects based on age and gender suggests statistically significant association of CRC with the 'C' allele of ApaI in patients >57 years of age at disease diagnosis and BsmI polymorphism in females. In addition, statistically significant differences were observed for the genotypic distributions of VDR-BsmI, ApaI and TaqI SNPs between Saudi Arabian population and several of the International HapMap project populations.

CONCLUSION

Despite the absence of correlation of the examined VDR polymorphisms with CRCs in the combined analysis, ApaI and BsmI loci are statistically significantly associated with CRC in elderly and female patients, respectively. These findings need further validation in larger cohorts prior to utilizing these SNPs as potential screening markers for colorectal cancers in Saudi population.

Vitamin D, Cancer Risk, and Mortality

Antiproliferative effects of 1,25-dihydroxyvitamin D, the biologically active form of vitamin D, are well established in various cell types by influencing cell differentiation and decreasing cell proliferation, growth, invasion, angiogenesis, and metastasis. Several meta-analyses showed that low serum levels of 25(OH)D was associated with colorectal cancer and overall mortality, while the association with cancer mortality was less consistent. VDR is a crucial mediator for the cellular effects of vitamin D and conflicting data have been reported for most malignancies. Beyond VDR, the biological effects of vitamin D are mediated by the vitamin D-binding protein. The GC (group-specific component) gene, encoding DBP, is highly polymorphic and several polymorphisms were investigated in association with cancer development with controversial results. Vitamin D supplementation was found to be associated with a reduced risk of overall mortality, reviewing all published trials on healthy subjects, whereas the evidence of an effect on cancer risk and mortality is less clear. Furthermore, long-term health effects of high doses of vitamin D, extended duration of supplementation, and the association with different baseline vitamin D levels remain to be investigated. In summary, epidemiological and preclinical studies support the development of vitamin D as preventative and therapeutic anticancer agents, with significant associations especially found for low vitamin D status with overall mortality and cancer outcome, more than cancer incidence. However, a definitive conclusion cannot be drawn and only large randomized clinical trials, both in healthy subjects and in cancer patients, will allow to draw definitive conclusions on the effect of vitamin D supplementation on cancer risk, prognosis, and mortality.