Genetic associations in the vitamin D receptor and colorectal cancer in African Americans and Caucasians

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.

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.

The burgeoning role of cytochrome P450-mediated vitamin D metabolites against colorectal cancer

The metabolites of vitamin D₃ (VD3) mediated by different cytochrome P450 (CYP) enzymes, play fundamental roles in many physiological processes in relation to human health. These metabolites regulate a variety of cellular signal pathways through the direct binding of activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Thus, the polymorphisms of VDR and VD3 metabolizing enzymes lead to differentiated efficiency of VD3 and further affect serum VD3 levels. Moreover, VDR activation is demonstrated to inhibit the growth of various cancers, including colorectal cancer. However, excessive intake of vitamin D may lead to hypercalcemia, which limits the application of vitamin D tremendously. In this review, we have summarized the advances in VD3 research, especially the metabolism map of VD3 and the molecular mechanisms of inhibiting growth and inducing differentiation in colorectal cancer mediated by VDR-associated cellular signal pathways. The relationship between VDR polymorphism and the risk of colorectal cancer is also illustrated. In particular, novel pathways of the activation of VD3 started by CYP11A1 and CYP3A4 are highlighted, which produce several noncalcemic and antiproliferative metabolites. At last, the hypothesis is put forward that further research of CYP-mediated VD3 metabolites may develop therapeutic agents for colorectal cancer without resulting in hypercalcemia.

Ethnic Manifestations of Gene Polymorphisms of Vitamin D Receptor (VDR) in Adolescents of Western Kazakhstan Region

BACKGROUND (OBJECTIVES)

The objective of the article is studying the connection of VDR gene polymorphisms with bone tissue mineral density and biochemical marker of 25-PO vitamin D in adolescents of both ethnic groups, living in Western Kazakhstan Region.

METHODS

The study included 110 relatively healthy children aged 13-18 years of Aktobe, the representatives of Kazakh ethnic group e 66 (Kazakh children) and Slavonic e 44 (Russian children). The groups were formed according to BTMD data, ethnic affiliation and according to content of vitamin D and gene polymorphism of vitamin D (VDR).

RESULTS

Genotype SS is negative marker in Kazakh adolescents of Western Kazakhstan Region for BTMD and 25-PO vitamin D; in children of Kazakh nationality with osteopathy sign, genotype SS occurs at almost twice the rate in comparison with Slavonic ethnic group and respectively by a factor of 2 less 25-PO vitamin D content.

CONCLUSION

Disorders of bone mineralization and metabolism depend on ethnic affiliation and presence of defined polymorphic genotypes of VDR gene molecular markers. Genotype Tt is a normal variant of gene polymorphism and is characterized by significantly less 25-PO vitamin D content in adolescents of Kazakh ethnic group, in comparison with their age mates of Slavonic ethnic group.

Associations between VDR gene polymorphisms and colorectal cancer susceptibility: an updated meta-analysis based on 39 case-control studies

BACKGROUND

Recent studies have reported the associations between vitamin D receptor (VDR) polymorphisms and colorectal cancer (CRC), but the results were not always consistent. This meta-analysis aims to evaluate whether VDR polymorphisms are associated with CRC susceptibility.

MATERIALS AND METHODS

Studies on the associations between VDR polymorphisms and CRC were retrieved from the Web of Science, PubMed, the Chinese Biomedical Database (CBM), Chinese National Knowledge Infrastructure (CNKI) and Wanfang (Chinese) databases. The odds ratio (OR) with 95% confidence intervals (CIs) was obtained.

RESULTS

Thirty-nine articles met all inclusion criteria and were included in the meta-analysis including 22101 CRC cases and 23696 healthy controls. The 39 articles consisted of five VDR gene polymorphisms including ApaI, FokI, BsmI, TaqI and Cdx2. The results of meta-analysis showed that the FokI polymorphism was on the fringe of statistically significant in the comparisons of F allele vs. f allele in fixed model (OR = 1.029, 95% CI = 0.999-1.059, Praw = 0.057, PFDR = 0.057). Moreover, for the associations between BsmI polymorphism with CRC, We observed significant differences in allele frequencies, the homozygous model and the dominant model between CRC patients and healthy controls (B vs. b: OR = 0.862, 95% CI = 0.761-0.976, Praw = 0.019, PFDR = 0.019; BB vs. bb: OR = 0.786, 95% CI = 0.636-0.972, Praw = 0.026, PFDR = 0.039; BB + Bb vs. bb: OR = 0.934, 95% CI = 0.888-0.982, Praw = 0.008, PFDR = 0.024, respectively).

CONCLUSIONS

This meta-analysis suggests that BsmI is associated with CRC risk and FokI might be a risk factor for CRC. However, these associations with CRC need further studied.

Colorectal Cancer Disparity in African Americans: Risk Factors and Carcinogenic Mechanisms

African Americans have the highest incidence and mortality rates of colorectal cancer (CRC) of any ethnic group in the United States. Although some of these disparities can be explained by differences in access to care, cancer screening, and other socioeconomic factors, disparities remain after adjustment for these factors. Consequently, an examination of recent advances in the understanding of ethnicity-specific factors, including genetic and environmental factors relating to risk of CRC, the biology of CRC progression, and the changes in screening and mortality, is important for evaluating our progress toward eliminating the disparities. An overarching limitation in this field is the number and sample size of studies performed to characterize the etiological bases of CRC incidence and mortality in African Americans. Despite this limitation, significant differences in etiology are manifest in many studies. These differences need validation, and their impacts on disparities need more detailed investigation. Perhaps most heartening, improvements in CRC screening can be attributed to the smallest difference in CRC incidence between African Americans and whites since the late 1980s. Cancer mortality, however, remains a persistent difference.

Vitamin D Receptor Gene Polymorphism and the Risk of Colorectal Cancer: A Nested Case-Control Study

Epidemiological and experimental evidence suggest that vitamin D is protective against the risk of colorectal cancer. Polymorphisms in the gene encoding vitamin D receptor (VDR), which mediates most of the known cellular effects of vitamin D, have been suggested to alter this association. Here, using a tag SNP approach, we comprehensively evaluated the role of common genetic variants in VDR and their interaction with plasma vitamin D levels in relation to colorectal cancer risk in Japanese populations. A total of 356 colorectal cancer cases and 709 matched control subjects were selected from the participants of the Japan Public Health Center-based Prospective Cohort Study. Among these subjects, 29 VDR single nucleotide polymorphisms (SNPs) were selected and genotyped, and plasma vitamin D concentrations were measured. Conditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of colorectal cancer, with adjustment for potential confounding factors. Among the results, eight VDR SNPs, namely rs2254210, rs1540339, rs2107301, rs11168267, rs11574113, rs731236, rs3847987 and rs11574143, the latter 5 of which were located in the 3′ region, were nominally associated with the risk of colorectal cancer (P = 0.01–0.048). Furthermore, of the above 5 3′ region SNPs, the inverse associations for 3 SNPs (rs11574113, rs3847987 and rs11574143) appeared to be evident only in those with high plasma vitamin D concentration. However, neither of these direct and suggestive interaction analysis associations was significant after multiple testing adjustment. Overall, the findings of this study provide only limited support for an association between common genetic variations in VDR and colorectal cancer risk in the Japanese population.

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.

Association of vdr, cyp27b1, cyp24a1 and mthfr gene polymorphisms with oral lichen planus risk

OBJECTIVES

The current study investigated the association between VDR EcoRV (rs4516035), FokI (rs2228570), ApaI (rs7975232) and TaqI (rs731236), CYP27B1 (rs4646536), CYP24A1 (rs2296241), and MTHFR (rs1801133) gene polymorphisms and risk of oral lichen planus (OLP) occurrence.

MATERIALS AND METHODS

The study group consisted of 65 oral lichen planus patients and 100 healthy blood donors in the control group. Single nucleotide polymorphisms were genotyped by real time PCR or PCR-restriction fragment length polymorphism (RFLP) method.

RESULTS

Heterozygous as well as mutated genotype of vitamin D receptor (VDR) FokI (rs2228570) polymorphism was associated with increased oral lichen planus risk in comparison with wild type genotype (odds ratio (OR) = 3.877, p = 0.017, OR = 38.153, p = 0.001, respectively). A significantly decreased OLP risk was observed for heterozygous genotype of rs2296241 polymorphism in CYP24A1 gene compared with the wild type form (OR = 0.314, p = 0.012). VDR gene polymorphisms ApaI and TaqI were in linkage disequilibrium (D' = 0.71, r(2) = 0.22). Identified haplotype AT was associated with decreased OLP risk (OR = 0.592, p = 0.047).

CONCLUSION

Our results highlight the possible important role of VDR FokI (rs2228570) and CYP24A1 rs2296241 gene polymorphisms for oral lichen planus susceptibility.

CLINICAL RELEVANCE

Identification of new molecular biomarkers could potentially contribute to determination of individuals with OLP predisposition.

Association of Vitamin D Receptor Cdx-2 Polymorphism With Cancer Risk: A Meta-Analysis

Vitamin D receptor (VDR) Cdx-2 polymorphism (rs11568820) has been indicated to be associated to cancer susceptibility. However, published studies reported mixed results. This meta-analysis was conducted to get a more accurate estimation of the association between Cdx-2 polymorphism and cancer risk.We identified 25 independent studies with a total of 34,018 subjects published prior to March 2015. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the susceptibility to cancer. Separate analyses were conducted on features of the population such as ethnicity, source of controls, and cancer types.Meta-analysis results showed that Cdx-2 polymorphism significantly increased cancer risk in the homozygous model in overall analysis. According to the further stratified analysis, significant association was found between Cdx-2 variant and cancer risk in American-Africans in the homozygous, recessive, and dominant comparison models. However, no significant associations were found in Caucasians and Asians. When stratified by different cancer types, significant association was observed between Cdx-2 variant and an increased risk of colorectal cancer in the homozygous, recessive, and dominant models. In addition, ovarian cancer susceptibility increased based on the homozygous and dominant comparison models.Our study indicated that VDR Cdx-2 polymorphism was associated with an increased cancer risk, particularly in American-Africans, colorectal, and ovarian cancers. However, other factors may impact on the association. Further multicenter studies are needed to confirm the effects of Cdx-2 polymorphism on cancer susceptibility.

Association of Dietary Vitamin D and Calcium With Genetic Polymorphisms in Colorectal Neoplasia

The incidence trends of colorectal cancer have varied over time, and there is wide geographical variation across the world. Regarding colorectal cancer, diverse modifiable environmental or intrinsic risk factors have been investigated. This review summarizes the effects of both dietary intake of vitamin D and calcium in particular and diet-associated genetic factors on colorectal cancer risk. We searched the electronic database PubMed for articles published between January 2000 and March 2015. We reviewed case-control studies that included dietary factors, genetic polymorphisms, and gene-diet interactions in association with colorectal cancer risk. Overall, 21 studies were selected as eligible studies. These studies demonstrated that dietary consumption of vitamin D and calcium may decrease the risk of colorectal cancer or adenoma. Colorectal carcinogenesis was discussed in conjunction with dietary factors and mediating genetic factors. The epidemiological findings suggested that the gene-diet interactions may possibly alter the associations between dietary intake, genetic polymorphisms, and the risk of colorectal cancer. However, the reported effects of the same potential factors on colorectal cancer risk were inconsistent, depending on the study population and geographical location. This finding may imply the necessity of considering the environmental differences and genetic variations existing between individuals or specified populations. Therefore, further studies are required to investigate modifiable risk factors in diverse locations to derive useful implications for colorectal neoplasia.

Genetic variations in VDR associated with prostate cancer risk and progression in a Korean population

Low levels of vitamin D are implicated as a potential risk factor for prostate cancer, and the vitamin D receptor (VDR) gene may be important in the onset and progression of prostate cancer. In this study, sequence variants in the VDR gene were investigated in a Korean study cohort to determine whether they are associated with prostate cancer risk. We evaluated the association between 47 single nucleotide polymorphisms (SNPs) in the VDR gene and prostate cancer risk as well as clinical characteristics (prostate-specific antigen level, clinical stage, pathological stage and Gleason score) in Korean men (272 prostate cancer patients and 173 benign prostatic hyperplasia patient who underwent a prostate biopsy, which was negative for malignancy) using unconditional logistic regression. The statistical analysis suggested that two VDR sequence variants (rs2408876 and rs2239182) had a significant association with prostate cancer risk (odds ratio [OR]. 1.41; p=0.03; OR, 0.73; p=0.05, respectively). Logistic analyses of the VDR polymorphisms with several prostate cancer related factors showed that several SNPs were significant; nine SNPs to PSA level, three to clinical stage, two to pathological stage, and three SNPs to the Gleason score. The results suggest that some VDR gene polymorphisms in Korean men might not only be associated with prostate cancer risk but also significantly related to prostate cancer-related risk factors such as PSA level, tumor stage, and Gleason score. However, current limitation for small cohort with not-healthy control group might have false positive effects; therefore it should be overcome via further large-scale validating studies.

Differential gene expression between African American and European American colorectal cancer patients

The incidence and mortality of colorectal cancer (CRC) is higher in African Americans (AAs) than other ethnic groups in the U. S., but reasons for the disparities are unknown. We performed gene expression profiling of sporadic CRCs from AAs vs. European Americans (EAs) to assess the contribution to CRC disparities. We evaluated the gene expression of 43 AA and 43 EA CRC tumors matched by stage and 40 matching normal colorectal tissues using the Agilent human whole genome 4x44K cDNA arrays. Gene and pathway analyses were performed using Significance Analysis of Microarrays (SAM), Ten-fold cross validation, and Ingenuity Pathway Analysis (IPA). SAM revealed that 95 genes were differentially expressed between AA and EA patients at a false discovery rate of ≤5%. Using IPA we determined that most prominent disease and pathway associations of differentially expressed genes were related to inflammation and immune response. Ten-fold cross validation demonstrated that following 10 genes can predict ethnicity with an accuracy of 94%: CRYBB2, PSPH, ADAL, VSIG10L, C17orf81, ANKRD36B, ZNF835, ARHGAP6, TRNT1 and WDR8. Expression of these 10 genes was validated by qRT-PCR in an independent test set of 28 patients (10 AA, 18 EA). Our results are the first to implicate differential gene expression in CRC racial disparities and indicate prominent difference in CRC inflammation between AA and EA patients. Differences in susceptibility to inflammation support the existence of distinct tumor microenvironments in these two patient populations.