Mechanistic Insights of Vitamin D Anticancer Effects

Advances in biomedical applications of vitamin D for VDR targeted management of obesity and cancer

BACKGROUND

1,25(OH)2D3 is a fat-soluble vitamin, involved in regulating Ca2+ homeostasis in the body. Its storage in adipose tissue depends on the fat content of the body. Obesity is the result of abnormal lipid deposition due to the prolonged positive energy balance and increases the risk of several cancer types. Furthermore, it has been associated with vitamin D deficiency and defined as a low 25(OH)2D3 blood level. In addition, 1,25(OH)2D3 plays vital roles in Ca2+-Pi and glucose metabolism in the adipocytes of obese individuals and regulates the expressions of adipogenesis-associated genes in mature adipocytes.

SCOPE AND APPROACH

The present contribution focused on the VDR mediated mechanisms interconnecting the obese condition and cancer proliferation due to 1,25(OH)2D3-deficiency in humans. This contribution also summarizes the identification and development of molecular targets for VDR-targeted drug discovery.

KEY FINDINGS AND CONCLUSIONS

Several studies have revealed that cancer development in a background of 1,25(OH)2D3 deficient obesity involves the VDR gene. Moreover, 1,25(OH)2D3 is also known to influence several cellular processes, including differentiation, proliferation, and adhesion. The multifaceted physiology of obesity has improved our understanding of the cancer therapeutic targets. However, currently available anti-cancer drugs are notorious for their side effects, which have raised safety issues. Thus, there is interest in developing 1,25(OH)2D3-based therapies without any side effects.

Biological evaluation of combinations of tyrosine kinase inhibitors with Inecalcitol as novel treatments for human chronic myeloid leukemia

Background

The use of tyrosine kinase inhibitors (TKIs) as a treatment for chronic myeloid leukemia (CML) has improved the natural history of the disease and increased the duration of survival. Tyrosine kinase inhibitors represent the success of target therapies that work on molecular targets, although some patients still have therapy failure. Vitamin D has antiproliferative, pro-apoptotic, and anti-angiogenic effects on cells, therefore it can be considered as a potential cancer preventative and treatment agent. Inecalcitol (TX-522) is the 14-epi-analogue of Calcitriol (1,25(OH)2-vitamin D3), and inhibits cancer cell proliferation more effectively than Calcitriol. This study was conducted to evaluate the antiproliferative and synergistic effects of the anticancer drugs Imatinib and Dasatinib in combinations with Inecalcitol on human chronic myeloid leukemia K-562 cells.

Method

The growth inhibitory activities of Inecalcitol, Imatinib, Dasatinib, and different combinations of one of the two drugs (Imatinib and Dasatinib) with Inecalcitol, were determined in vitro using MTT assay against K-562 cell line.

Results

Inecalcitol, Imatinib, and Dasatinib showed potent antiproliferative activities against K-562 cells with GI50 values of 5.6 µM, 0.327 µM, and 0.446 nM, respectively. Combinations of Imatinib or Dasatinib with different concentrations of Inecalcitol increased significantly the antiproliferative activities and potencies of both drugs (****p < 0.0001), with optimal GI50 values of 580 pM (Imatinib) and 0.51 pM (Dasatinib). Furthermore, the combination treatments showed synergistic interaction between the antileukemic drugs and Inecalcitol, with combination indices (CI) < 1.

Conclusion

The study demonstrated that the human chronic myeloid leukemia K-562 cells were subjected to a synergistic growth inhibitory impact when antileukemic drugs (Imatinib or Dasatinib) were combined with Inecalcitol, therefore, it is recommended that these combinations be viewed as promising novel antileukemic medications and used in place of individual medications with lower dosages and negligible side effects in the treatment of CML.

Role of Vitamin D in the diagnosis of acute Myeloid Leukemia

A range of hematological and biochemical markers have been investigated in Acute Myeloid Leukemia (AML) patients to determine the relationship between cancer growth and metabolic problems. This study aimed to determine the effects of vitamin D deficiency in Iraqi patients with acute myeloid leukemia who had recently been diagnosed. There was a significant inverse correlation between the total serum cholesterol (TC) level of acute myeloid leukemia (AML) patients group [(148.77±12.2) for males, (165.29±9.64) for females] and the control group [(164.50±7.26) for males, (180.05±7.31) for females], also an inverse correlation between high-density lipoprotein (HDL) level of acute myeloid leukemia (AML) patients group [(46.00±2.04) for males, (46.18±1.08) for females] and control group [(54.25±1.86) for males,(51.94±1.37) for females]. A significant difference was between the serum triglyceride (TG) level of acute myeloid leukemia (AML) patients group [(128.71±13.07) for males, (152.48±10.6) for females] and control group [85.12±11.30) for male, (90.50±10.90) for females], also between vitamin D level of acute myeloid leukemia (AML) patients group [(17.23±1.18) for males, (12.96±0.74) for females] and control group [(42.62±1.43) for males, (40.76±0.82) for females]. A statistically significant difference was between the serum calcium levels of individuals with acute myeloid leukemia [(8.99±0.32) for males, (8.91±0.23) for females] and the control group [(13.13±1.16) for males, (10.73±0.28) for females]. AML patients can benefit from vitamin D treatment, according to a pairwise analysis of receiver operating characteristic (ROC) curves. The above results are related to concluding that Vitamin D can be utilized as a diagnostic test for AML patients. Keywords; acute myeloid leukemia (AML), Hypereosinophilia, ROC curve, hypocholesterolemia, vitamin D.

Vitamin D and neurodegenerative diseases

Neurodegenerative diseases, featured by progressive loss of structure or function of neurons, are considered incurable at present. Movement disorders like tremor and postural instability, cognitive or behavioral disorders such as memory impairment are the most common symptoms of them and the growing patient population of neurodegenerative diseases poses a serious threat to public health and a burden on economic development. Hence, it is vital to prevent the occurrence of the diseases and delay their progress. Vitamin D can be transformed into a hormone in vivo with both genomic and non-genomic actions, exerting diverse physiological effects. Cumulative evidence indicates that vitamin D can ameliorate neurodegeneration by regulating pertinent molecules and signaling pathways including maintaining Ca²⁺ homeostasis, reducing oxidative stress, inhibiting inflammation, suppressing the formation and aggregation of the pathogenic protein, etc. This review updates discoveries of molecular mechanisms underlying biological functions of vitamin D in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and vascular dementia. Clinical trials investigating the influence of vitamin D supplementation in patients with neurodegenerative diseases are also summarized. The synthesized information will probably provoke an enhanced understanding of the neuroprotective roles of vitamin D in the nervous system and provide therapeutic options for patients with neurodegenerative diseases in the future.

Dairy intake and the risk of pancreatic cancer: the Japan Collaborative Cohort Study (JACC Study) and meta-analysis of prospective cohort studies

Dairy product intake was suggested to reduce the risk of gastrointestinal cancers. This study investigated the association between dairy product intake and the risk of pancreatic cancer (PAC) using a prospective cohort study and meta-analysis of prospective cohort studies. First, we included 59 774 people aged 40-79 years from the Japan Collaborative Cohort Study (JACC Study). The Cox regression was used to compute the hazard ratios (HR) and 95 % CI of incident PAC for individuals who reported the highest intakes of milk, cheese and yogurt compared with not consuming the corresponding dairy products. Then, we combined our results with those from other four prospective cohort studies that were eligible after searching several databases, in a meta-analysis, using the fixed-effects model before evaluating publication bias and heterogeneity across studies. In the JACC Study, the highest v. no intakes of milk, cheese and yogurt were not associated with the reduced risk of PAC after a median follow-up of 13·4 years: HR (95 % CI) = 0·93 (0·64, 1·33), 0·91 (0·51, 1·62) and 0·68 (0·38, 1·21), respectively. The results did not significantly change in the meta-analysis: 0·95 (0·82, 1·11) for milk, 1·16 (0·87, 1·55) for cheese and 0·91 (0·79, 1·05) for yogurt. The meta-analysis showed no signs of publication bias or heterogeneity across studies. To conclude, consumption of milk, cheese and yogurt was not associated with the risk of PAC either in the JACC Study or the meta-analysis.

Vitamin D Metabolites in Nonmetastatic High-Risk Prostate Cancer Patients with and without Zoledronic Acid Treatment after Prostatectomy

Simple Summary

Recent research on prostate cancer and vitamin D is controversial. We measured three vitamin D₃ metabolites in 32 selected prostate cancer patients after surgery at four time points over four years. Within a large European study, half of the patients were prophylactically treated with zoledronic acid (ZA); the others received a placebo. After the study start, all the patients daily took calcium and vitamin D₃. The development of metastasis was not affected by ZA treatment. While two vitamin D metabolites had higher values after the study’s start, with constant follow-up values, the 1,25(OH)₂-vitamin D₃ concentrations remained unchanged. The latter form was the only metabolite that was higher in the patients with metastasis as compared to those without bone metastasis. This result is surprising. However, it is too premature to discuss possible prognostic value yet. Our results should be confirmed in larger cohorts.

Abstract

There are limited and discrepant data on prostate cancer (PCa) and vitamin D. We investigated changes in three vitamin D₃ metabolites in PCa patients after prostatectomy with zoledronic acid (ZA) treatment regarding their metastasis statuses over four years. In 32 patients from the ZEUS trial, 25(OH)D₃, 24,25(OH)₂D₃, and 1,25(OH)₂D₃ were measured with liquid chromatography coupled with tandem mass spectrometry at four time points. All the patients received daily calcium and vitamin D₃. Bone metastases were detected in 7 of the 17 ZA-treated patients and in 5 of the 15 controls (without ZA), without differences between the groups (p = 0.725). While 25(OH)D₃ and 24,25(OH)₂D₃ increased significantly after the study’s start, with following constant values, the 1,25(OH)₂D₃ concentrations remained unchanged. ZA treatment did not change the levels of the three metabolites. 25(OH)D₃ and 24,25(OH)₂D₃ were not associated with the development of bone metastases. In contrast, 1,25(OH)₂D₃ was also higher in patients with bone metastasis before the study’s start. Thus, in high-risk PCa patients after prostatectomy, 25(OH)D₃, 24,25(OH)₂D₃, and 1,25(OH)₂D₃ were not affected by supportive ZA treatment or by the development of metastasis over four years, with the exception of 1,25(OH)₂D₃, which was constantly higher in metastatic patients. There might be potential prognostic value if the results can be confirmed.

The effects of consuming a low-fat yogurt fortified with nano encapsulated vitamin D on serum pro-oxidant-antioxidant balance (PAB) in adults with metabolic syndrome; a randomized control trial

BACKGROUND AND AIM

The current study aimed to assess the effect of fortified yogurt with nano-encapsulated vitamin D on serum pro-oxidant anti-oxidant balance (PAB) in adults with or without metabolic syndrome.

METHODS

In a quadruple blind clinical trial study, 139 adults with an age range of 30-50 years were randomly selected to receive either 1500 IU nano-encapsulated vitamin D fortified yogurt or placebo for ten weeks. Before and after the intervention period, blood sample was taken to determine the serum levels of vitamin D, pro-oxidant-antioxidant balance (PAB), and high-sensitivity C-reactive protein (hs-CRP). The laboratory tests were checked at baseline and at the end of the treatment.

RESULTS

Serum vitamin D increased significantly, from 14.47 ± 6.07 ng/mL to 21.39 ± 6.54 ng/mL (P < 0.001) after ten weeks in the intervention group. Serum hs-CRP and PAB were significantly lower following consumption period in intervention group [1.95(0.4-8.15) g/dL vs. 1.35(0.25-3.62) g/dL; P = 0.013] and (135.19 ± 42.4 HK vs. 115.39 ± 44.69) HK; P = 0.018] respectively. There were no significant differences between the intervention and control groups regarding weight and BMI at the end of the intervention period (p > 0.05).

CONCLUSION

Low-fat yogurt fortified with nano-encapsulated vitamin D was found to reduce serum PAB levels in adults with metabolic syndrome.

PRACTICAL APPLICATION

The findings of the present study indicated that a low-fat yogurt fortified with 1500 IU nano-encapsulated vitamin D for ten weeks, leads to a significant reduction in serum hs-CRP and PAB concentrations highlighted the anti-inflammatory/anti-oxidative effect of vitamin D.

Essential sufficiency of zinc, ω-3 polyunsaturated fatty acids, vitamin D and magnesium for prevention and treatment of COVID-19, diabetes, cardiovascular diseases, lung diseases and cancer

Despite the development of a number of vaccines for COVID-19, there remains a need for prevention and treatment of the virus SARS-CoV-2 and the ensuing disease COVID-19. This report discusses the key elements of SARS-CoV-2 and COVID-19 that can be readily treated: viral entry, the immune system and inflammation, and the cytokine storm. It is shown that the essential nutrients zinc, ω-3 polyunsaturated fatty acids (PUFAs), vitamin D and magnesium provide the ideal combination for prevention and treatment of COVID-19: prevention of SARS-CoV-2 entry to host cells, prevention of proliferation of SARS-CoV-2, inhibition of excessive inflammation, improved control of the regulation of the immune system, inhibition of the cytokine storm, and reduction in the effects of acute respiratory distress syndrome (ARDS) and associated non-communicable diseases. It is emphasized that the non-communicable diseases associated with COVID-19 are inherently more prevalent in the elderly than the young, and that the maintenance of sufficiency of zinc, ω-3 PUFAs, vitamin D and magnesium is essential for the elderly to prevent the occurrence of non-communicable diseases such as diabetes, cardiovascular diseases, lung diseases and cancer. Annual checking of levels of these essential nutrients is recommended for those over 65 years of age, together with appropriate adjustments in their intake, with these services and supplies being at government cost. The cost:benefit ratio would be huge as the cost of the nutrients and the testing of their levels would be very small compared with the cost savings of specialists and hospitalization.

Assessment of a Novel Vitamin D3 Formulation with Nanostructured Lipid Carriers for Transdermal Delivery

OBJECTIVE

Develop and assess a transdermal emulsion loaded with nanostructured lipid carriers for vitamin D3 supplementation.

METHODS

Vitamin D3 loaded nanostructured lipid carriers, produced via high shear homogenization and ultrasonication, were assessed for their particle size, distribution, morphology, zeta potential, entrapment efficiency, and cytotoxicity. They were incorporated into a transdermal vehicle, and the stability and ex vivo permeation were evaluated.

RESULTS

Spherical nanoparticles were developed with a particle size of 192.5 nm, a polydispersity index of 0.13, a zeta potential of -29.0 mV, and an entrapment efficiency of 99.75%. They were stable (particle size and distribution) for 15 days when stored in a refrigerator and for 30 days at room temperature and 32 °C. The nanoparticles decreased the drug cytotoxicity against fibroblasts, as shown by IC50 (nanoparticle: 32.48 μg mL-1; vitamin D3: 16.73 μg mL-1). The emulsion loaded with nanoparticles minimized the degradation of vitamin D3 when compared with the nanoparticle dispersion. Additionally, the emulsion provided the skin permeation of vitamin D3 following the recommended daily allowance.

CONCLUSION

To the best of our knowledge, this is the first study to use nanostructured lipid carriers for transdermal delivery of vitamin D. The developed formulation is a promising strategy to overcome the vitamin D3 variable oral bioavailability. It also represents a comfortable route of administrationd. Thus it could be beneficial for patients and clinicians. However, further studies are needed to allow the permeation of larger amounts of vitamin D3, and the combination of these nanoparticles with microneedles would be interesting.

Comprehensive Stability Study of Vitamin D3 in Aqueous Solutions and Liquid Commercial Products

Vitamin D3 has numerous beneficial effects, such as musculoskeletal, immunomodulatory, and neuroprotective. However, its instability is the main obstacle to formulating quality products. Despite increased attention and growing use, data on vitamin D3 stability is scarce because data from individual studies is inconclusive and mostly qualitative. Therefore, we have systematically investigated the influence of various factors (temperature, light, oxygen, pH, concentration, and metal ions) on its stability in aqueous media using a stability-indicating HPLC-UV method. First-order kinetics fitted its degradation under all tested conditions except light and oxygen. In both cases, the established models in chemical kinetics were inappropriate and upgraded with the Weibull model. Metal ions and acidic conditions had the main destabilizing effect on vitamin D3 in aqueous media, but these solutions were successfully stabilized after the addition of ethylenediaminetetraacetic acid (EDTA), ascorbic acid, and citric acid, individually and in combination. EDTA showed the most significant stabilizing effect. Synergism among antioxidants was not observed. Our findings on vitamin D3 instability in aqueous media also correlated with its instability in commercial products. Vitamin D3 aqueous products require proper stabilization, thereby signifying the importance and contribution of the obtained results to the formulation of stable and quality products.

Inhibition of calcitriol inactivating enzyme CYP24A1 gene expression by flavonoids in hepatocellular carcinoma cells under normoxia and hypoxia

A vast number of epidemiological, preclinical and in vitro experimental data strongly indicate the anticancer potential of calcitriol, the biologically active form of vitamin D. However, for the implementation of a vitamin D based cancer therapy the increased deactivation of calcitriol in cancer cells by overexpressed CYP24A1 hydroxylase should be suppressed. Inhibition of this enzyme expression or activity nowadays is considered as important aspect of anticancer therapeutic strategies. Herein, we investigated the impact of genistein, biochanin A, formonentin and kaempferol on the expression of the CYP24A1 gene induced by calcitriol in hepatocellular cancer cells Huh7 under normoxia (21%O₂) or hypoxia (1%O₂). We demonstrate that calcitriol induces CYP24A1 under normoxia and hypoxia, but this induction is significantly more potent under hypoxia, the typical microenvironment of solid tumors. In the presence of isoflavones genistein, biochanin A and formononetin, this induction is abrogated to the control levels under normoxia, while under hypoxia there is some differentiation in suppression efficacy between these compounds with genistein ≥ biochanin > formononetin. At the same time, kaempferol turned out to be completely ineffective in the suppression of CYP24A1 gene expression.

Dicer increases the indication for trastuzumab treatment in gastric cancer patients via overexpression of human epidermal growth factor receptor 2

The low proportion of gastric cancer (GC) patients with high HER2 expression limits the clinical application of trastuzumab, a humanized epidermal growth factor receptor 2 (HER2) antibody targeting for GC treatment. We found that Dicer was positively correlated with HER2 expression in GC tissue by immunostaining as well as induce HER2 overexpression without increasing invasiveness of GC cell. In addition, both the growth of GC referring to cell proliferation, invasion, migration and apoptosis was inhibited by Dicer overexpression. Moreover, the HER2 overexpression induced by Dicer provided more effective and additive target for trastuzumab to amplify the inhibition effect for GC cells in vitro and in vivo. Furthermore, as assessed in a subsequent experiment, calcitriol induced HER2 overexpression and amplified the inhibition effect of trastuzumab in GC cells referring to proliferation. Our finding demonstrated the calcitriol might increase indication of trastuzumab by inducing HER2 overexpression in GC patients. Dicer would be a potential target that extend the clinical indications of HER2 antibody in patients with low or negative HER2, who were not fit for HER2 antibody treatment before.

Zinc, ω-3 polyunsaturated fatty acids and vitamin D: An essential combination for prevention and treatment of cancers

Zinc, ω-3 polyunsaturated fatty acids (PUFAs) and vitamin D are essential nutrients for health, maturation and general wellbeing. Extensive literature searches have revealed the widespread similarity in molecular biological properties of zinc, ω-3 PUFAs and vitamin D, and their similar anti-cancer properties, even though they have different modes of action. These three nutrients are separately essential for good health, especially in the aged. Zinc, ω-3 PUFAs and vitamin D are inexpensive and safe as they are fundamentally natural and have the properties of correcting and inhibiting undesirable actions without disturbing the normal functions of cells or their extracellular environment. This review of the anticancer properties of zinc, ω-3 PUFAs and vitamin D is made in the context of the hallmarks of cancer. The anticancer properties of zinc, ω-3 PUFAs and vitamin D can therefore be used beneficially through combined treatment or supplementation. It is proposed that sufficiency of zinc, ω-3 PUFAs and vitamin D is a necessary requirement during chemotherapy treatment and that clinical trials can have questionable integrity if this sufficiency is not checked and maintained during efficacy trials.

Calcitriol Suppresses HIF-1 and HIF-2 Transcriptional Activity by Reducing HIF-1/2α Protein Levels via a VDR-Independent Mechanism

Hypoxia-inducible transcription factors 1 and 2 (HIFs) are major mediators of cancer development and progression and validated targets for cancer therapy. Although calcitriol, the biologically active metabolite of vitamin D, was attributed with anticancer properties, there is little information on the effect of calcitriol on HIFs and the mechanism underling this activity. Here, we demonstrate the negative effect of calcitriol on HIF-1/2α protein levels and HIF-1/2 transcriptional activity and elucidate the molecular mechanism of calcitriol action. We also reveal that the suppression of vitamin D receptor (VDR) expression by siRNA does not abrogate the negative regulation of HIF-1α and HIF-2α protein levels and HIF-1/2 transcriptional activity by calcitriol, thus testifying that the mechanism of these actions is VDR independent. At the same time, calcitriol significantly reduces the phosphorylation of Akt protein kinase and its downstream targets and suppresses HIF-1/2α protein synthesis by inhibiting HIF1A and EPAS1 (Endothelial PAS domain-containing protein 1) mRNA translation, without affecting their mRNA levels. On the basis of the acquired data, it can be proposed that calcitriol reduces HIF-1α and HIF-2α protein levels and inhibits HIF-1 and HIF-2 transcriptional activity by a VDR-independent, nongenomic mechanism that involves inhibition of PI3K/Akt signaling pathway and suppression of HIF1A and EPAS1 mRNA translation.

CYP24A1 rs1570669 Variant Has a Protective Effect against Tumors of the Urinary System

BACKGROUND

Common malignant tumors of the urinary system include renal cell carcinoma, bladder carcinoma, and prostate cancer. The research on the CYP24A1 gene for prostate cancer is mainly concentrated in European and American populations, and there are few studies in the Chinese population. Therefore, we selected bladder cancer, prostate cancer, and renal cancer as the research objects to explore the influence of CYP24A1 on the genetic susceptibility of urinary system tumors.

MATERIALS AND METHODS

rs6068816, rs2296241, rs2762934, and rs1570669 in 529 patients and 523 controls were genotyped via the Agena MassARRAY. Logistic regression analysis was used to evaluate the odd ratios (ORs) and 95% confidence intervals (CIs) of two SNPs with susceptibility of urinary system cancer. Database predicts the expression of the CYP24A1 gene in urinary system cancer.

RESULTS

Individuals with the AG genotype of CYP24A1 rs1570669 has a 28% lower risk of developing urinary system tumors (OR = 0.72, 95% CI: 0.56-1.13, p = 0.016) and has a 31% lower risk of developing renal cancer (OR = 0.69, 95% CI: 0.51-0.92, p = 0.012).

CONCLUSIONS

CYP24A1 rs1570669 may play an important role in the susceptibility of tumors of the urinary system and renal cancer.

TaqI and ApaI Variants of Vitamin D Receptor Gene Increase the Risk of Colorectal Cancer in a Saudi Population

Background:

Polymorphisms in the gene encoding the vitamin D receptor (VDR) affect the protective role of vitamin D against many types of cancers, including colorectal cancer (CRC).

Objective:

The objective of this study was to assess the effect of four major polymorphisms of the VDR gene (ApaI, TaqI, BsmI and FokI) on the risk of CRC in a Saudi population.

Materials and Methods:

This case–control study recruited 132 CRC patients from the oncology clinics at King Abdulaziz University Hospital and 124 healthy controls from the blood bank at King Fahad General Hospital, Jeddah, Saudi Arabia, between September 2017 and August 2018. All participants were Saudis and aged 20–80 years. Genomic DNA samples were extracted from the peripheral blood cells and amplified with polymerase chain reaction. The resulting fragments were digested with different endonucleases to reveal the genotypes using the restriction fragment length polymorphism technique. The genotype distribution and allele frequency, odds ratio (OR), risk ratio (RR) and P values were determined with contingency table analysis following Hardy–Weinberg equilibrium equation.

Results:

For the ApaI single-nucleotide polymorphism (SNP) (rs7975232), only the heterozygous (Aa) genotype increased the risk of CRC (OR = 3.4, RR = 2.3, and P < 0.0001), whereas the TaqI SNP (rs731236) carriers with either the heterozygous (Tt) or homozygous (tt) genotype displayed an increased risk for the disease (OR = 6.18, RR = 4, P < 0.0001; OR = 3, RR = 2.4, P = 0.02, respectively). In contrast, heterozygous (Bb) and homozygous (bb) carriers of the BsmI SNP (rs1544410) had significantly lower risk for CRC (P < 0.0001). Finally, for the FokI SNP (rs2228570), there was no association with CRC risk.

Conclusion:

This study found that VDR SNPs ApaI and TaqI increase the risk of CRC, whereas BsmI reduces the risk of CRC in the selected Saudi population. Therefore, ApaI and TaqI SNPs could potentially be used as a diagnostic biomarker for CRC. However, the molecular mechanisms by which these variants increase or decrease the risk of CRC need to be investigated.

Differentiation of Cancer Stem Cells by Using Synthetic Small Molecules: Toward New Therapeutic Strategies against Therapy Resistance

Despite the existing arsenal of anti-cancer drugs, 10 million people die each year worldwide due to cancers; this highlights the need to discover new therapies based on innovative modes of action against these pathologies. Current chemotherapies are based on the use of cytotoxic agents, targeted drugs, monoclonal antibodies or immunotherapies that are able to reduce or stop the proliferation of cancer cells. However, tumor eradication is often hampered by the presence of resistant cells called cancer stem-like cells or cancer stem cells (CSCs). Several strategies have been proposed to specifically target CSCs such as the use of CSC-specific antibodies, small molecules able to target CSC signaling pathways or drugs able to induce CSC differentiation rendering them sensitive to classical chemotherapy. These latter compounds are the focus of the present review, which aims to report recent advances in anticancer-differentiation strategies. This therapeutic approach was shown to be particularly promising for eradicating tumors in which CSCs are the main reason for therapeutic failure. This general view of the chemistry and mechanism of action of compounds inducing the differentiation of CSCs could be particularly useful for a broad range of researchers working in the field of anticancer therapies as the combination of compounds that induce differentiation with classical chemotherapy could represent a successful approach for future therapeutic applications.

Associations of C-reactive Protein with 25-hydroxyvitamin D in 24 Specific Diseases: A Cross-sectional Study from NHANES

Most diseases might be associated with acute or chronic inflammation, and the role of vitamin D in diseases has been extensively explored in recent years. Thus, we examined the associations of one of the best markers for inflammation ― C-reactive protein (CRP) with 25-hydroxyvitamin D [25(OH)D] in 24 specific diseases. We performed cross-sectional analyses among 9,809 subjects aged ≥18 years who participated in the U.S. National Health and Nutrition Examination Survey (NHANES) in 2007~2010. The generalized additive model (GAM) was used to explore the associations of CRP with 25(OH)D in different diseases, adjusted for the age, gender, examination period and race. Distributions of CRP were significantly different (P < 0.05) in gender, examination period and race, and distributions of 25(OH)D were different (P < 0.05) in the examination period and race. Generally, CRP was negatively associated with 25(OH)D for majority diseases. 25(OH)D was negatively associated with CRP generally, and the associations were disease-specific and disease category-specific. In respiratory, gastrointestinal and mental diseases, the associations tended to be approximately linear. While in metabolic diseases, the associations were nonlinear, and the slope of the nonlinear curve decreased with 25(OH)D, especially when 25(OH)D < 30 μg/L.

Immunomodulatory Effects of Vitamin D in Pregnancy and Beyond

In addition to its role in calcium homeostasis and bone formation, a modulatory role of the active form of vitamin D on cells of the immune system, particularly T lymphocytes, has been described. The effects of vitamin D on the production and action of several cytokines has been intensively investigated in recent years. In this connection, deficiency of vitamin D has been associated with several autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), Hashimoto Thyroiditis (HT), and multiple sclerosis (MS). In a successful pregnancy, the maternal immune response needs to adapt to accommodate the semiallogeneic fetus. Disturbances in maternal tolerance are implicated in infertility and pregnancy complications such as miscarriages (RM) and preeclampsia (PE). It is well-known that a subset of T lymphocytes, regulatory T cells (Tregs) exhibit potent suppressive activity, and have a crucial role in curtailing the destructive response of the immune system during pregnancy, and preventing autoimmune diseases. Interestingly, vitamin D deficiency is common in pregnant women, despite the widespread use of prenatal vitamins, and adverse pregnancy outcomes such as RM, PE, intrauterine growth restriction have been linked to hypovitaminosis D during pregnancy. Research has shown that autoimmune diseases have a significant prevalence within the female population, and women with autoimmune disorders are at higher risk for adverse pregnancy outcomes. Provocatively, dysregulation of T cells plays a crucial role in the pathogenesis of autoimmunity, and adverse pregnancy outcomes where these pathologies are also associated with vitamin D deficiency. This article reviews the immunomodulatory role of vitamin D in autoimmune diseases and pregnancy. In particular, we will describe the role of vitamin D from conception until delivery, including the health of the offspring. This review highlights an observational study where hypovitaminosis D was correlated with decreased fertility, increased disease activity, placental insufficiency, and preeclampsia in women with APS.

Differential response of lung cancer cell lines to vitamin D derivatives depending on EGFR, KRAS, p53 mutation status and VDR polymorphism

Vitamin D reveals antiproliferative activity against many types of cancer cells. Calcitriol (1,25D3), the most active form of vitamin D3, acts mainly through the vitamin D receptor, regulating the expression of target genes. Cells with reasonable expression of VDR are considered to be sensitive to antiproliferative activity of 1,25D3. However, a few alleles of the VDR gene are correlated with higher or lower response to 1,25D3 treatment. The goal of our study was to establish if cells differing in EGFR, KRAS, p53 mutation status and VDR polymorphism were sensitive to antiproliferative activity of selected vitamin D derivatives (VDDs). In our search for the lead VDD against human lung cancer cells, we selected, for this study, low calcemic analogs of active forms of vitamin D2 and D3 that had previously shown anticancer potential. The selected cell lines revealed differential response to VDDs. The highest proliferation inhibition was observed for EGFR mutant cells while a weaker response was observed for KRAS and/or p53 mutant cells. 24,24-Dihomo-1,25D3 (PRI-1890) showed the highest activity on the VDD-sensitive cell lines (A549, HCC827, NCI-H1299, and NCI-H1703). Therefore, PRI-1890 was selected as the lead VDD for further structure optimization. None of the VDDs used in this study showed antiproliferative activity against A-427 and Calu-3. VDR polymorphisms correlated inversely with sensitivity to the antiproliferative activity of VDDs since we observed less transcriptionally active form of VDR in HCC827 cells sensitive to VDD, while more transcriptionally active form was observed in NCI-H358 cells that were stimulated by VDDs to proliferate. Lack of KRAS and p53 mutations in HCC827 cells may be, therefore, responsible for the higher antiproliferative activity of VDDs, while the presence of KRAS and/or p53 mutations in other cell lines might prevent antiproliferative activity even though the VDDs were transcriptionally active as assessed on increased CYP24A1 expression. VDR gene polymorphism is not directly responsible for the sensitivity of tested cells to VDDs.

Vitamin D aggravates breast cancer by inducing immunosuppression in the tumor bearing mouse

The aim of this approach is to test the effects and related mechanism of vitamin D (VD) treatment on the outcomes of breast cancer. BALB/c mice were injected with 4T1 breast cancer cell suspension. The test group was treated with VD reagent. The survival and tumor size of mice were observed. The proliferation of 4T1 in vitro was detected by MTS analysis. The changes of immune parameters and microenvironment in mice were evaluated by flow cytometry and real-time RT-PCR. Our results demonstrate that VD administration caused a decline in survival time and raising the volume of tumor, the decreasing numbers of CD3⁺CD4⁺ T, CD3⁺CD8⁺ T and CD4⁺T-bet⁺IFN-γ⁺ Th1 cells and transcriptions of T-bet and IFN-γ, an increasing number of myeloid-derived suppressor cells and transcription of TGF-β. Our data suggest that the routine clinical application of any strategies targeting VD status for breast cancer therapy is deserved serious consideration.

The association between iron and vitamin D status in Arab adolescents

OBJECTIVE

Both vitamin D and Fe micronutrient deficiencies are common in Saudi Arabia but the association between them is unclear. The present study aimed to determine whether Fe indices are associated with vitamin D status and other metabolic markers in Arab adolescents.

DESIGN

Single-centre, cross-sectional study gathering anthropometrics, glucose and lipid profile. Serum 25-hydroxyvitamin D (25(OH)D), Fe, total iron-binding capacity (TIBC), transferrin saturation (%) and other parameters were measured.

SETTING

Vitamin D School Project Database, King Saud University (2014-2016).

PARTICIPANTS

Arab adolescents aged 10-17 years randomly selected from the Vitamin D School Project Database (170 Saudi students; 100 girls, seventy boys).

RESULTS

Among Fe indices, only TIBC was found to be significantly and inversely associated with 25(OH)D (r = -0·20; P < 0·01) and only in girls (r = -0·20; P < 0·05). Among cardiometabolic parameters, serum Fe was associated with TAG in boys (r = 0·36; P < 0·01) and inversely associated with HDL-cholesterol in girls (r = -0·29; P < 0·05). Age was the most significant predictor of serum Fe for all participants, accounting for 5 % (R2 = 0·05; P = 0·004) of variance perceived. Serum 25(OH)D and age, on the other hand, were the most significant predictors for TIBC, accounting for 10·1 % (R2 = 0·10; P < 0·001) of variance perceived.

CONCLUSIONS

Among healthy Arab adolescents, the association between vitamin D and Fe indices, particularly TIBC, is modest, inverse and sex-dependent. Larger studies with inclusion of markers such as hepcidin and ferritin, vitamin D metabolites and endogenous sex hormones may provide a clearer view of this complex association.

Severe Vitamin D Deficiency Increases Mortality Among Patients With Liver Cirrhosis Regardless of the Presence of HCC

BACKGROUND

The aim of this study was to investigate the association between vitamin D deficiency (<10 mg/ml) and mortality in patients with and without hepatocellular carcinoma (HCC) in a cohort of patients with liver cirrhosis.

MATERIALS AND METHODS

A prospective study was conducted among 345 patients with liver cirrhosis.

RESULTS

At enrolment, 46 (13.3%) patients had HCC. Severe vitamin D deficiency was associated with mortality (p<0.01). At the survival analysis, alpha-fetoprotein >10 ng/ml (p=0.003), vitamin D deficiency (p<0.001), a Model for End-Stage Liver Disease score ≥15 (p<0.001), Child-Pugh class B and C (versus A) (p<0.001) and the presence of active HCC (p<0.001) were strongly associated with death. At the multivariate Cox regression analysis, only Child-Pugh class B and C (versus A) and vitamin D deficiency were found to be significantly associated with death during the follow-up period (p<0.001 and p=0.006, respectively).

CONCLUSION

Vitamin D deficiency is common in patients with HCC, it is associated with active HCC and it negatively affects the overall survival of patients with cirrhosis.

Evaluation of the serum prooxidant-antioxidant balance before and after vitamin D supplementation in adolescent Iranian girls

PURPOSE

Oxidative stress is caused by an imbalance between the antioxidant defenses and pro-oxidant production in favor of pro-oxidant production. Vitamin D has the potential for both pro- and anti-oxidative effects. The aim of this study was to assess the effect of high dose vitamin D supplementation on the prooxidant-antioxidant balance (PAB) in Iranian girls attending High School.

MATERIALS AND METHODS

A total of 464 girls aged 12-18 years were asked to take vitamin D capsules containing 50000IU vitamin D₃ once a week for a period of 9 weeks. All variables were determined at baseline and after 9 weeks of intervention. Fasting blood samples were taken from all subjects. The serum levels of 25OHD were measured using an electrochemiluminescence method. Serum PAB levels were determined using an ELISA reader at a wavelength of 450 nm.

RESULTS

Vitamin D supplementation was associated with an increase in serum PAB (P < 0.001) and a reduction in serum LDL-C (P < 0.001), total cholesterol (P < 0.001) and HDL-C (P < 0.01) serum levels in Iranian adolescent girls. The results obtained from the current study show that there were significant improvements in weight (P < 0.001), BMI (P < 0.001) and FBG (P = 0.02) in adolescent girls who had 50-74.9 nmol/L serum 25OHD levels compared to <50 nmol/L ones after the vitamin D supplementation. There was no significant association between the serum PAB and all biochemical factors (P > 0.05 for all variables).

CONCLUSIONS

The results showed that vitamin D supplementation has increased the PAB levels in teenage girls.

Vitamin D Stimulates Cardiomyocyte Proliferation and Controls Organ Size and Regeneration in Zebrafish

Attaining proper organ size during development and regeneration hinges on the activity of mitogenic factors. Here, we performed a large-scale chemical screen in embryonic zebrafish to identify cardiomyocyte mitogens. Although commonly considered anti-proliferative, vitamin D analogs like alfacalcidol had rapid, potent mitogenic effects on embryonic and adult cardiomyocytes in vivo. Moreover, pharmacologic or genetic manipulation of vitamin D signaling controlled proliferation in multiple adult cell types and dictated growth rates in embryonic and juvenile zebrafish. Tissue-specific modulation of vitamin D receptor (VDR) signaling had organ-restricted effects, with cardiac VDR activation causing cardiomegaly. Alfacalcidol enhanced the regenerative response of injured zebrafish hearts, whereas VDR blockade inhibited regeneration. Alfacalcidol activated cardiac expression of genes associated with ErbB2 signaling, while ErbB2 inhibition blunted its effects on cell proliferation. Our findings identify vitamin D as mitogenic for cardiomyocytes and other cell types in zebrafish and indicate a mechanism to regulate organ size and regeneration.

Vitamin D Supplementation Modestly Reduces Serum Iron Indices of Healthy Arab Adolescents

Vitamin D deficiency has been shown to affect iron status via decreased calcitriol production, translating to decreased erythropoiesis. The present study aimed to determine for the first time whether vitamin D supplementation can affect iron levels among Arab adolescents. A total of 125 out of the initial 200 Saudi adolescents with vitamin D deficiency (serum 25(OH)D < 50 nmol/L) were selected from the Vitamin D-School Project of King Saud University in Riyadh, Saudi Arabia. Cluster randomization was done in schools, and students received either vitamin D tablets (1000 IU/day) (N = 53, mean age 14.1 ± 1.0 years) or vitamin D-fortified milk (40IU/200mL) (N = 72, mean age 14.8 ± 1.4 years). Both groups received nutritional counseling. Anthropometrics, glucose, lipids, iron indices, and 25(OH)D were measured at baseline and after six months. Within group analysis showed that post-intervention, serum 25(OH)D significantly increased by as much as 50%, and a parallel decrease of −42% (p-values <0.001 and 0.002, respectively) was observed in serum iron in the tablet group. These changes were not observed in the control group. Between-group analysis showed a clinically significant increase in serum 25(OH)D (p = 0.001) and decrease in iron (p < 0.001) in the tablet group. The present findings suggest a possible inhibitory role of vitamin D supplementation in the iron indices of healthy adolescents whose 25(OH)D levels are sub-optimal but not severely deficient, implying that the causal relationship between both micronutrients may be dependent on the severity of deficiency, type of iron disorder, and other vascular conditions that are known to affect hematologic indices. Well-designed, randomized trials are needed to confirm the present findings.

Relationship between serum 25-hydroxyvitamin D and red blood cell indices in German adolescents

Since the impact of vitamin D on red blood cell formation has not been well studied, we aimed at assessing the putative link between serum 25-hydroxyvitamin D (25[OH]D) concentrations and hematological markers of erythropoiesis in a large cohort of German adolescents aged 11 to 17 years. In total, 5066 participants from the population-based, nationally representative KiGGS study (Kinder- und Jugendgesundheitssurvey, German Health Interview and Examination Survey for Children and Adolescents) were grouped into either tertiles or clinically accepted cutoff levels for serum 25(OH)D. Results demonstrated significant and inverse correlations between 25(OH)D levels and several hematological parameters including hemoglobin concentration (r = - 0.04, p = 0.003), mean corpuscular hemoglobin (r = - 0.11, p < 0.001), red blood cell count (r = - 0.04, p = 0.002), and soluble transferrin receptor (r = - 0.1, p < 0.001), whereas, in contrast, serum 25(OH)D was positively correlated to the mean corpuscular volume of erythrocytes (r = 0.08, p < 0.001). Multinomial regression models adjusted for clinically relevant confounders confirmed statistically significant differences between the two strata of 25(OH)D groups with respect to red blood cell markers (hemoglobin concentration, red blood cell count, mean corpuscular volume, and corpuscular hemoglobin, as well as iron and soluble transferrin receptor).

CONCLUSIONS

The link between serum 25(OH)D and several important hematological parameters may point to an inhibitory role of vitamin D in the regulation of erythropoiesis in adolescents. What is Known: • The physiological effects of vitamin D on calcium homeostasis and bone metabolism have been established. • However, much less is known about the impact of circulating vitamin D on erythropoiesis. What is New: • Data from the KiGGS study in German adolescents demonstrated significant associations between serum vitamin D concentrations and red blood cell indices. • Further studies should be conducted to decipher the underlying mechanisms of vitamin D on erythropoiesis.

New insights into the role of vitamin D in hepatocellular carcinoma

In addition to being crucial for host immune defense, vitamin D is involved in cell proliferation, apoptosis, differentiation, inflammation, invasion and metastasis, angiogenesis and micro-RNA modulation. To date, clinical studies have demonstrated that vitamin D deficiency is common not only in patients with chronic liver diseases but also in those with hepatocellular carcinoma (HCC). Experimental studies have also demonstrated that vitamin D and its receptors are related to the occurrence of HCC and the prognoses of patients with HCC. Areas covered: In this review, we discuss the potential anti-tumor role of vitamin D in HCC based on current findings from epidemiological studies, basic science, and clinical studies and provide new insights into the pathogenesis and treatment of HCC. Expert commentary: Recent studies have revealed the anti-tumor effects of vitamin D to a certain degree. Vitamin D and its analogs may provide new treatment targets and prognostic factors for HCC that might be essential for the primary or secondary prevention of HCC and the monitoring of its progression.

Depleting ovarian cancer stem cells with calcitriol

Cancer stem cells (CSCs) represent the root of many solid tumors including ovarian cancer. Eradication of CSCs represents a novel cancer therapeutic strategy. Calcitriol, also known as 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], is an active metabolite of vitamin D, functioning as a potent steroid hormone. Calcitriol has shown anti-tumor effects in various cancers by regulating multiple signaling pathways. It has been reported that calcitriol can regulate the properties of normal and CSCs. However, the effect of calcitriol on the ovarian cancer growth and ovarian CSCs is still unclear. Here, by using a mouse subcutaneous xenograft model generated with human ovarian cancer cells, we have demonstrated that administration of calcitriol is able to strikingly delay the tumor growth. Calcitriol treatment can also deplete the ovarian CSC population characterized by ALDH⁺ and CD44⁺CD117⁺; decrease their capacity to form sphere under the CSC culture condition, and reduce the frequency of tumor-initiating cells, as evaluated by in vivo limiting dilution analysis. Mechanistic investigation revealed that calcitriol depletes CSCs via the nuclear vitamin D receptor (VDR)-mediated inhibition of the Wnt pathway. Furthermore, the activation of VDR pathway is more sensitive to calcitriol in ovarian CSCs than in non-CSCs, although the expression levels of VDR are comparable. Taken together, our data indicate that calcitriol is able to deplete the ovarian CSC population by inhibiting their Wnt signaling pathway, consequently, impeding the growth of xenograft tumors.

Vitamin D, the placenta and early pregnancy: effects on trophoblast function

Pregnancy is associated with significant changes in vitamin D metabolism, notably increased maternal serum levels of active vitamin D, 1,25-dihydroxyvitamin (1,25(OH)₂D). This appears to be due primarily to increased renal activity of the enzyme 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) that catalyzes synthesis of 1,25(OH)₂D, but CYP27B1 expression is also prominent in both the maternal decidua and fetal trophoblast components of the placenta. The precise function of placental synthesis of 1,25(OH)₂D remains unclear, but is likely to involve localized tissue-specific responses with both decidua and trophoblast also expressing the vitamin D receptor (VDR) for 1,25(OH)₂D. We have previously described immunomodulatory responses to 1,25(OH)₂D by diverse populations of VDR-expressing cells within the decidua. The aim of the current review is to detail the role of vitamin D in pregnancy from a trophoblast perspective, with particular emphasis on the potential role of 1,25(OH)₂D as a regulator of trophoblast invasion in early pregnancy. Vitamin D deficiency is common in pregnant women, and a wide range of studies have linked low vitamin D status to adverse events in pregnancy. To date, most of these studies have focused on adverse events later in pregnancy, but the current review will explore the potential impact of vitamin D on early pregnancy, and how this may influence implantation and miscarriage.

Vitamin D and melanoma: state of the art and possible therapeutic uses

Despite the presence of several studies in literature, the real connection between vitamin D serological levels, vitamin D receptor and melanoma remains unclear, probably because of the complex correlation between vitamin D and melanoma. Indeed, UV radiations are not reported as the main risk factor for melanoma in non-sun-exposed, while systemic immunosuppression, anatomical and physiological features may contribute to malignancy. Therefore, the correlation between melanoma cells in sun-exposed areas and vitamin D, as well as vitamin D receptor could be different from the one in melanoma of sun-shielded sites. These differences may also explain the controversial results reported in the literature regarding the correlation between melanoma and vitamin D, as well as the different outcomes in melanoma patients treated with vitamin D as adjuvant therapy. The aim of this review is to highlight the most recent findings about vitamin D and melanoma, focusing on the anatomic site of the primary tumor as well as on the possible therapeutic uses of vitamin D in melanoma patients.

Differential gene expression by 1,25(OH)2D3 in an endometriosis stromal cell line

Endometriosis is a common female reproductive disease characterized by invasion of endometrial cells into other organs, frequently causing pelvic pain and infertility. Alterations of the vitamin D system have been linked to endometriosis incidence and severity. To shed light on the potential mechanism for these associations, we examined the effects of 1,25(OH)₂D₃ on gene expression in endometriosis cells. Stromal cell lines derived from endometriosis tissue were treated with 1,25(OH)₂D₃, and RNA-seq was used to identify genes differentially expressed between treated and untreated cells. Gene ontology and pathway analyses were carried out using Partek Flow and Ingenuity software suites, respectively. We identified 1627 genes that were differentially expressed (886 down-regulated and 741 up-regulated) by 1,25(OH)₂D₃. Only one gene, CYP24A1, was strongly up-regulated (369-fold). Many genes were strongly down-regulated. 1,25(OH)₂D₃ treatment down-regulated several genetic pathways related to neuroangiogenesis, cellular motility, and invasion, including pathways for axonal guidance, Rho GDP signaling, and matrix metalloprotease inhibition. These findings support a role for vitamin D in the pathophysiology of endometriosis, and provide new targets for investigation into possible causes and treatments.

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.

The role of vitamin D in male fertility: A focus on the testis

In the last decade, vitamin D has emerged as a pleiotropic molecule with a multitude of autocrine, paracrine and endocrine functions, mediated by classical genomic as well as non-classical non-genomic actions, on multiple target organs and systems. The expression of vitamin D receptor and vitamin D metabolizing enzymes in male reproductive system, particularly in the testis, suggests the occurrence of vitamin D synthesis and regulation as well as function in the testis. The role of vitamin D in the modulation of testis functions, including hormone production and spermatogenesis, has been investigated in animals and humans. Experimental studies support a beneficial effect of vitamin D on male fertility, by modulating hormone production through genomic and non-genomic actions, and, particularly, by improving semen quality essentially through non-genomic actions. However, clinical studies in humans are controversial. Indeed, vitamin D seems to contribute to the modulation of the bioavailable rather than total testosterone. Moreover, although an increased prevalence or risk for testosterone deficiency was reported in men with vitamin D deficiency in observational studies, the majority of interventional studies demonstrated the lack of effect of vitamin D supplementation on circulating levels of testosterone. The most consistent effect of vitamin D was reported on semen quality. Indeed, vitamin D was shown to be positively associated to sperm motility, and to exert direct actions on spermatozoa, including non-genomic driven modulation of intracellular calcium homeostasis and activation of molecular pathways involved in sperm motility, capacitation and acrosome reaction. The current review provides a summary of current knowledge on the role of vitamin D in male fertility, by reporting clinical and experimental studies in humans and animals addressing the relationship between vitamin D and testis function.

The roles of UVB and vitamin D in reducing risk of cancer incidence and mortality: A review of the epidemiology, clinical trials, and mechanisms

Global cancer incidence and mortality rates are high and increasing. Thus, it is imperative to find novel solutions to preventing cancer incidence and treating it at an affordable yet efficacious manner. The solar UVB-vitamin D-cancer hypothesis was first proposed in 1980 based on a geographical ecological study. Since then, numerous ecological and observational studies as well as studies of mechanisms have provided support for the hypothesis. However, observational studies have not provided consistent support, in part due to using a single blood draw from any season to use for serum 25-hydroxyvitamin D [25(OH)D] concentration in prospective studies with long follow-up times. Case-controls studies, in which blood is drawn near time of diagnosis, and prospective studies in which blood is drawn in the sunnier half of the year, are more likely to find significant inverse relations between 25(OH)D and cancer incidence. Three vitamin D plus calcium clinical trials have found significant reduction in all-cancer incidence. This paper reviews the evidence for vitamin D in reducing incidence of and increasing survival from breast, colorectal, lung, ovarian, pancreatic, and prostate cancer. The epidemiological evidence provides strong support for all of these types of cancer except for non-aggressive prostate cancer. Studies of the cellular mechanisms of vitamin D action in different cancer cell types, strongly indicate that vitamin D can exert protective and anti-tumorigenic activities that would retard cellular transformation, hyperplasia and cancer progression. Based on the scientific evidence reviewed in this paper, individuals and health providers can consider increasing 25(OH)D concentrations through sensible sun exposure and/or vitamin D supplementation to reduce risk of and, in conjunction with standard care, treat cancer. Public health acceptance of vitamin D for cancer prevention and treatment requires stronger support from vitamin D clinical trials.

Vitamin D analogues: Potential use in cancer treatment

The vitamin D receptor (VDR) is a member of the thyroid-steroid family of nuclear transcription factors. Following binding of the active form of vitamin D, i.e., 1,25(OH)₂D3 (also known as calcitriol) and interaction with co-activators and co-repressors, VDR regulates the expression of several different genes. Although relatively little work has been carried out on VDR in human cancers, several epidemiological studies suggest that low circulating levels of vitamin D are associated with both an increased risk of developing specific cancer types and poor outcome in patients with specific diagnosed cancers. These associations apply especially in colorectal and breast cancer. Consistent with these findings, calcitriol as well as several of its synthetic analogues have been shown to inhibit tumor cell growth in vitro and in diverse animal model systems. Indeed, some of these vitamin D analogues with low calcemic inducing activity (e.g., EB1089, inecalcitol, paricalcitol) have progressed to clinical trials in patients with cancer. Preliminary results from these trials suggest that these vitamin D analogues have minimal toxicity, but clear evidence of efficacy remains to be shown. Although evidence of efficacy for mono-treatment with vitamin D analogues is currently lacking, several studies have reported that supplementation with calcitriol or the presence of high endogenous circulating levels of vitamin D enhances response to standard therapies.

Antiangiogenic cancer treatment: The great discovery and greater complexity (Review)

The discovery of tumor angiogenesis opened a new path in fighting cancer. The approval of different antiangiogenic agents, most targeting vascular endothelial growth factor (VEGF) signaling, has either increased the effectiveness of standard chemotherapy or even replaced it by offering better patient outcomes. However, an increasing number of preclinical and clinical observations have shown that the process of angiogenesis is far from clearly understood. Apart from targeting the VEGF pathway, novel strategies aim to influence other molecular factors that are involved in tumor angiogenesis. In addition, naturally occurring compounds seem to offer additional agents for influencing angiogenesis. The first concept of antiangiogenic therapy aimed to destroy tumor vessels, while it turned out that, paradoxically, antiangiogenic drugs normalized vasculature and as a result offered an improvement in chemotherapeutic delivery. In order to design an effective treatment schedule, methods for detecting the time window of normalization and biomarkers predicting patient response are needed. The initial idea that antiangiogenic therapy would be resistance-free failed to materialize and currently we still face the obstacle of resistance to antiangiogenic therapy.

Commonalities in the Association between PPARG and Vitamin D Related with Obesity and Carcinogenesis

The PPAR nuclear receptor family has acquired great relevance in the last decade, which is formed by three different isoforms (PPARα, PPARβ/δ, and PPAR ϒ). Those nuclear receptors are members of the steroid receptor superfamily which take part in essential metabolic and life-sustaining actions. Specifically, PPARG has been implicated in the regulation of processes concerning metabolism, inflammation, atherosclerosis, cell differentiation, and proliferation. Thus, a considerable amount of literature has emerged in the last ten years linking PPARG signalling with metabolic conditions such as obesity and diabetes, cardiovascular disease, and, more recently, cancer. This review paper, at crossroads of basic sciences, preclinical, and clinical data, intends to analyse the last research concerning PPARG signalling in obesity and cancer. Afterwards, possible links between four interrelated actors will be established: PPARG, the vitamin D/VDR system, obesity, and cancer, opening up the door to further investigation and new hypothesis in this fascinating area of research.